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Velleman K40x0, the very model of an all-round amp
On Oct 19, 12:11 am, "Iain Churches" wrote:
"Andre Jute" wrote Real tubies build real valve amp kits, like my Velleman K4000, three EL34 per side for 18W in Class A and 101W in Class B (measured, they claim only 16/96W). Now that is an amp that leaves hairy footprints. Interesting you should mention the Velleman. It is indeed a good sounding amp. It is a long time since I have seen a K4000, but I seem to recollect it had four EL34's in push pull parallel per side. PPP. It seems as though the K4000 is discontinued. Mine is ancient. Early to mid-1990s, at a guess, without looking up the reviews I wrote of it. I listened to a 4040 not too long ago, with a pair of splendid Tannoy Canterbury SE speakers. Very pleasing indeed. The amp was running far below its full power potential. Quite a bizarre thing to say, I suppose, but the Velleman is probably overmatched to the Tannoys. It has around 16 to 18W in Class A alone. I sometimes used mine for driving a bass bin, where its 100W in Class A/B could sometimes come into play, at least theoretically (I'm not a headbanger). The noise floor was exceptionally low. Later, a quick look on the bench revealed the noise floor to be 100µV, so a SNR of 105dB and at 96W, the THD was only 0.1% It depends on your outlook whether you view the Velleman K40x0 as that rare thing, a perfect all-round amp -- or as a perfectly schizophrenic amp: on the one hand superbly well designed and good-sounding, escpecially in that very hefty Class A segment, a delicate match to ESL-63, on the other hand a brutish bass thumper on demand. As an all- round amp of excellent quality and durability it is of course a very great bargain at the price. The Belgians know how to make more than just chocolates:-) We used to make a round trip of 50 miles to buy Belgian chocolates in Cork... Regards Iain Andre Jute Visit Jute on Amps at http://members.lycos.co.uk/fiultra/ "wonderfully well written and reasoned information for the tube audio constructor" John Broskie TubeCAD & GlassWare "an unbelievably comprehensive web site containing vital gems of wisdom" Stuart Perry Hi-Fi News & Record Review |
Velleman K40x0, the very model of an all-round amp
On Oct 19, 6:27 am, Andre Jute wrote:
On Oct 19, 12:11 am, "Iain Churches" wrote: "Andre Jute" wrote Real tubies build real valve amp kits, like my Velleman K4000, three EL34 per side for 18W in Class A and 101W in Class B (measured, they claim only 16/96W). Now that is an amp that leaves hairy footprints. This was the all-on-a PCB, toroidal output transformer kit offered for well in four figures through OCSL at around that time. I thought it was a stinky deal then and worse now. Toroid outputs and PCB mounted power tubes are just not a good idea. |
Velleman K40x0, the very model of an all-round amp
overmatched to the Tannoys. It has around 16 to 18W in Class A alone. I sometimes used mine for driving a bass bin, where its 100W in Class A/B could sometimes come into play, at least theoretically (I'm not a headbanger). hey-Hey!!!, An amp with maximum output happening with one phase of its PP set cut off is *NOT* class A. A real class A amp has both phases conducting at maximum power, and not from some variable pitch grid winding, remote cut-off stuff either. That Vellman amp is an AB, and barely so at that. cheers, Douglas |
Velleman K40x0, the very model of an all-round amp
In article . com,
Multi-grid wrote: hey-Hey!!!, An amp with maximum output happening with one phase of its PP set cut off is *NOT* class A. A real class A amp has both phases conducting at maximum power, and not from some variable pitch grid winding, remote cut-off stuff either. Is there actually a power tube with a variable pitch grid winding designed to do this? I never heard about it before, inquiring minds want to know more. Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/ |
Velleman K40x0, the very model of an all-round amp
On Oct 19, 3:50 pm, Multi-grid wrote:
overmatched to the Tannoys. It has around 16 to 18W in Class A alone. I sometimes used mine for driving a bass bin, where its 100W in Class A/B could sometimes come into play, at least theoretically (I'm not a headbanger). hey-Hey!!!, An amp with maximum output happening with one phase of its PP set cut off is *NOT* class A. A real class A amp has both phases conducting at maximum power, and not from some variable pitch grid winding, remote cut-off stuff either. That Vellman amp is an AB, and barely so at that. cheers, Douglas What are you on about, Dougles? I just told you, it is a class AB amp. Class AB amps by definition have some class A output and the rest in Class B. If you want an unadulterated Class A amp with a 100W output, you're going to be paying real money, and if you're a snob who wants it in SE, you're going to be paying Range Rover Vogue money. I know; I built an 80W SE amp, which of course by definition ran only in Class A. The Velleman is relatively inexpensive, very sturdy, very good value amplifier kit from the most famous makers of all kinds of electronic kits in the world. But its price will look a tip to a doorman by the time you finish paying for a 100W Class A amp. And what's that rubbish about "maximum output" anyway? By definition a class AB amp's Class A output is at some lower power than maximum, otherwise it would be a Class A amp, period. The whole point about a Class AB amp is that most music is played where such an amp makes its sweetest sounds, but that it has headroom for any contingency, though you sacrifice a little something in quality when that headroom is taken up. If your taste is so refined that you must have nothing but Class A, there are a bunch of designs for Class A amps on my netsite. And, for the sake of completeness, my own favourite everyday amp is my own T113 "Triple Threat" design, which runs PP EL34s in triode and strictly in Class A. But you'd need about 8 of those to get 100W... You know an audiophool snob when he starts talking about "pure" Class A... Andre Jute Visit Jute on Amps at http://members.lycos.co.uk/fiultra/ "wonderfully well written and reasoned information for the tube audio constructor" John Broskie TubeCAD & GlassWare "an unbelievably comprehensive web site containing vital gems of wisdom" Stuart Perry Hi-Fi News & Record Review |
Velleman K40x0, the very model of an all-round amp
On Oct 20, 3:34 am, Andre Jute wrote:
On Oct 19, 3:50 pm, Multi-grid wrote: overmatched to the Tannoys. It has around 16 to 18W in Class A alone. I sometimes used mine for driving a bass bin, where its 100W in Class A/B could sometimes come into play, at least theoretically (I'm not a headbanger). hey-Hey!!!, An amp with maximum output happening with one phase of its PP set cut off is *NOT* class A. A real class A amp has both phases conducting at maximum power, and not from some variable pitch grid winding, remote cut-off stuff either. That Vellman amp is an AB, and barely so at that. cheers, Douglas What are you on about, Dougles? I just told you, it is a class AB amp. Class AB amps by definition have some class A output and the rest in Class B. No it doesn't, it has no power in Class A. That's why it is called an AB amp. It is really simple. If you want an unadulterated Class A amp with a 100W output, you're going to be paying real money, and if you're a snob who wants it in SE, you're going to be paying Range Rover Vogue money. I know; I built an 80W SE amp, which of course by definition ran only in Class A. The Velleman is relatively inexpensive, very sturdy, very good value amplifier kit from the most famous makers of all kinds of electronic kits in the world. But its price will look a tip to a doorman by the time you finish paying for a 100W Class A amp. I don't recall ever telling you what I wanted, or owned, or for that matter what I've built. None of that has any bearing on your marketing- based dafynishion of what you'd like an AB amp to be. And what's that rubbish about "maximum output" anyway? By definition a class AB amp's Class A output is at some lower power than maximum, otherwise it would be a Class A amp, period. Just because both of the finals are conducting does not mean it is Class A. That is reserved for amps that keep both conducting *AT FULL POWER*. Why *******ize the definition just because some marketing fool likes says it's OK? A Class AB amp doesn't have any Class A output. Both phases conducting does not make Class A....or is that too hard to grasp? The whole point about a Class AB amp is that most music is played where such an amp makes its sweetest sounds, but that it has headroom for any contingency, though you sacrifice a little something in quality when that headroom is taken up. If your taste is so refined that you must have nothing but Class A, there are a bunch of designs for Class A amps on my netsite. I don't think I'll be considering any of those amps. Kinda off-the- rack and boring. And, for the sake of completeness, my own favourite everyday amp is my own T113 "Triple Threat" design, which runs PP EL34s in triode and strictly in Class A. But you'd need about 8 of those to get 100W... You know an audiophool snob when he starts talking about "pure" Class A... Probably just somebody who knows how to use the language properly. You can join the club anytime you wish to conduct yourself properly....and leave it just as quickly. cheers, Douglas |
Velleman K40x0, the very model of an all-round amp
On Oct 20, 2:18 am, John Byrns wrote:
In article . com, Multi-grid wrote: hey-Hey!!!, An amp with maximum output happening with one phase of its PP set cut off is *NOT* class A. A real class A amp has both phases conducting at maximum power, and not from some variable pitch grid winding, remote cut-off stuff either. Is there actually a power tube with a variable pitch grid winding designed to do this? I never heard about it before, inquiring minds want to know more. Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/ Hi John, I don't know of any either, but given the definition of Class A, I thought it wise to rule out the remote cut-off behaviour that *COULD* provide a loophole to somebody fixed on disagreement, yes? cheers, Douglas |
Velleman K40x0, the very model of an all-round amp
On Oct 19, 7:27 am, Andre Jute wrote:
On Oct 19, 12:11 am, "Iain Churches" wrote: "Andre Jute" wrote Real tubies build real valve amp kits, like my Velleman K4000, three EL34 per side for 18W in Class A and 101W in Class B (measured, they claim only 16/96W). Now that is an amp that leaves hairy footprints. Interesting you should mention the Velleman. It is indeed a good sounding amp. It is a long time since I have seen a K4000, but I seem to recollect it had four EL34's in push pull parallel per side. PPP. It seems as though the K4000 is discontinued. Mine is ancient. Early to mid-1990s, at a guess, without looking up the reviews I wrote of it. I listened to a 4040 not too long ago, with a pair of splendid Tannoy Canterbury SE speakers. Very pleasing indeed. The amp was running far below its full power potential. Quite a bizarre thing to say, I suppose, but the Velleman is probably overmatched to the Tannoys. It has around 16 to 18W in Class A alone. I sometimes used mine for driving a bass bin, where its 100W in Class A/B could sometimes come into play, at least theoretically (I'm not a headbanger). The noise floor was exceptionally low. Later, a quick look on the bench revealed the noise floor to be 100µV, so a SNR of 105dB and at 96W, the THD was only 0.1% It depends on your outlook whether you view the Velleman K40x0 as that rare thing, a perfect all-round amp -- or as a perfectly schizophrenic amp: on the one hand superbly well designed and good-sounding, escpecially in that very hefty Class A segment, a delicate match to ESL-63, on the other hand a brutish bass thumper on demand. As an all- round amp of excellent quality and durability it is of course a very great bargain at the price. The Belgians know how to make more than just chocolates:-) We used to make a round trip of 50 miles to buy Belgian chocolates in Cork... Regards Iain Andre Jute Visit Jute on Amps athttp://members.lycos.co.uk/fiultra/ "wonderfully well written and reasoned information for the tube audio constructor" John Broskie TubeCAD & GlassWare "an unbelievably comprehensive web site containing vital gems of wisdom" Stuart Perry Hi-Fi News & Record Review Of all the decent amps out there why would you pick something like This? |
Velleman K40x0, the very model of an all-round amp
On Oct 19, 6:37 pm, Multi-grid wrote:
On Oct 20, 3:34 am, Andre Jute wrote: On Oct 19, 3:50 pm, Multi-grid wrote: overmatched to the Tannoys. It has around 16 to 18W in Class A alone. I sometimes used mine for driving a bass bin, where its 100W in Class A/B could sometimes come into play, at least theoretically (I'm not a headbanger). hey-Hey!!!, An amp with maximum output happening with one phase of its PP set cut off is *NOT* class A. A real class A amp has both phases conducting at maximum power, and not from some variable pitch grid winding, remote cut-off stuff either. That Vellman amp is an AB, and barely so at that. cheers, Douglas What are you on about, Dougles? I just told you, it is a class AB amp. Class AB amps by definition have some class A output and the rest in Class B. No it doesn't, it has no power in Class A. That's why it is called an AB amp. It is really simple. If you want an unadulterated Class A amp with a 100W output, you're going to be paying real money, and if you're a snob who wants it in SE, you're going to be paying Range Rover Vogue money. I know; I built an 80W SE amp, which of course by definition ran only in Class A. The Velleman is relatively inexpensive, very sturdy, very good value amplifier kit from the most famous makers of all kinds of electronic kits in the world. But its price will look a tip to a doorman by the time you finish paying for a 100W Class A amp. I don't recall ever telling you what I wanted, or owned, or for that matter what I've built. None of that has any bearing on your marketing- based dafynishion of what you'd like an AB amp to be. And what's that rubbish about "maximum output" anyway? By definition a class AB amp's Class A output is at some lower power than maximum, otherwise it would be a Class A amp, period. Just because both of the finals are conducting does not mean it is Class A. That is reserved for amps that keep both conducting *AT FULL POWER*. Why *******ize the definition just because some marketing fool likes says it's OK? A Class AB amp doesn't have any Class A output. Both phases conducting does not make Class A....or is that too hard to grasp? The whole point about a Class AB amp is that most music is played where such an amp makes its sweetest sounds, but that it has headroom for any contingency, though you sacrifice a little something in quality when that headroom is taken up. If your taste is so refined that you must have nothing but Class A, there are a bunch of designs for Class A amps on my netsite. I don't think I'll be considering any of those amps. Kinda off-the- rack and boring. And, for the sake of completeness, my own favourite everyday amp is my own T113 "Triple Threat" design, which runs PP EL34s in triode and strictly in Class A. But you'd need about 8 of those to get 100W... You know an audiophool snob when he starts talking about "pure" Class A... Probably just somebody who knows how to use the language properly. You can join the club anytime you wish to conduct yourself properly....and leave it just as quickly. Yes, I see what this is about: another clown storming into RAT with a mission to see me off. Thanks for coming, Dougles, but I don't think I would care to belong to any club that lets you in. cheers, Douglas |
Velleman K40x0, the very model of an all-round amp
On Oct 20, 6:42 am, Andre Jute wrote:
On Oct 19, 6:37 pm, Multi-grid wrote: On Oct 20, 3:34 am, Andre Jute wrote: On Oct 19, 3:50 pm, Multi-grid wrote: overmatched to the Tannoys. It has around 16 to 18W in Class A alone. I sometimes used mine for driving a bass bin, where its 100W in Class A/B could sometimes come into play, at least theoretically (I'm not a headbanger). hey-Hey!!!, An amp with maximum output happening with one phase of its PP set cut off is *NOT* class A. A real class A amp has both phases conducting at maximum power, and not from some variable pitch grid winding, remote cut-off stuff either. That Vellman amp is an AB, and barely so at that. cheers, Douglas What are you on about, Dougles? I just told you, it is a class AB amp. Class AB amps by definition have some class A output and the rest in Class B. No it doesn't, it has no power in Class A. That's why it is called an AB amp. It is really simple. If you want an unadulterated Class A amp with a 100W output, you're going to be paying real money, and if you're a snob who wants it in SE, you're going to be paying Range Rover Vogue money. I know; I built an 80W SE amp, which of course by definition ran only in Class A. The Velleman is relatively inexpensive, very sturdy, very good value amplifier kit from the most famous makers of all kinds of electronic kits in the world. But its price will look a tip to a doorman by the time you finish paying for a 100W Class A amp. I don't recall ever telling you what I wanted, or owned, or for that matter what I've built. None of that has any bearing on your marketing- based dafynishion of what you'd like an AB amp to be. And what's that rubbish about "maximum output" anyway? By definition a class AB amp's Class A output is at some lower power than maximum, otherwise it would be a Class A amp, period. Just because both of the finals are conducting does not mean it is Class A. That is reserved for amps that keep both conducting *AT FULL POWER*. Why *******ize the definition just because some marketing fool likes says it's OK? A Class AB amp doesn't have any Class A output. Both phases conducting does not make Class A....or is that too hard to grasp? The whole point about a Class AB amp is that most music is played where such an amp makes its sweetest sounds, but that it has headroom for any contingency, though you sacrifice a little something in quality when that headroom is taken up. If your taste is so refined that you must have nothing but Class A, there are a bunch of designs for Class A amps on my netsite. I don't think I'll be considering any of those amps. Kinda off-the- rack and boring. And, for the sake of completeness, my own favourite everyday amp is my own T113 "Triple Threat" design, which runs PP EL34s in triode and strictly in Class A. But you'd need about 8 of those to get 100W... You know an audiophool snob when he starts talking about "pure" Class A... Probably just somebody who knows how to use the language properly. You can join the club anytime you wish to conduct yourself properly....and leave it just as quickly. Yes, I see what this is about: another clown storming into RAT with a mission to see me off. Thanks for coming, Dougles, but I don't think I would care to belong to any club that lets you in. cheers, Douglas- Hide quoted text - - Show quoted text -- Hide quoted text - - Show quoted text - hey-Hey!!!, Well Andre, you can imagine my mission to be what ever it you want. Again, that has no bearing what so ever on your mis-use of the definition. Please stay on topic if you'd be so kind. Quit clouding the issue please. Do people go 'storming into RAT with a mission to see me off' alot lately? Are you paranoid or something? Where would you get such an idea? I'll type slowly so you can understand it, this club I referred to only requires its members to use accepted audio definitions and terms properly. Of course it doesn't really exist, save for in metaphore...but an accomplished writer like you would know all this, right? While you're at it, a schematic of your 80W SE amp would be nice to look at. cheers, Douglas |
Velleman K40x0, the very model of an all-round amp
"Andre Jute" wrote in message oups.com... On Oct 19, 12:11 am, "Iain Churches" wrote: The noise floor was exceptionally low. Later, a quick look on the bench revealed the noise floor to be 100µV, so a SNR of 105dB and at 96W, the THD was only 0.1% It depends on your outlook whether you view the Velleman K40x0 as that rare thing, a perfect all-round amp -- (snip) Oh,. I don't think it is anywhere near that! I regard it as a good-sounding DIY project, no more. The fact that the tube sockets are mounted on the PCB really put me off. I have a Radford STA 100. So no contest. Iain |
Velleman K40x0, the very model of an all-round amp
(snip) Oh,. I don't think it is anywhere near that! I regard it as a good-sounding DIY project, no more. The fact that the tube sockets are mounted on the PCB really put me off. I have a Radford STA 100. So no contest. Iain I owned one that another fellow put together. I remember replacing some of the 10 ohm resistors because of excessive cathode current draw. It was a nice looking amp, with plenty of power. The PCBs were a turn-off, but not a killer for me (Hey, if you want to have some REAL fun, do component-level work on an Audio Research D-70. What a nightmare to repair!) In my continuing search for the holy grail of sound, that amp went to a new owner. To my ears, the sound was kind of harsh for a tube amp, and lacking excitement. I agree that it is "a good-sounding DIY project." Jon |
Velleman K40x0, the very model of an all-round amp
"Jon Yaeger" wrote in message ... I owned one that another fellow put together. I remember replacing some of the 10 ohm resistors because of excessive cathode current draw. It was a nice looking amp, with plenty of power. The PCBs were a turn-off, but not a killer for me (Hey, if you want to have some REAL fun, do component-level work on an Audio Research D-70. What a nightmare to repair!) In my continuing search for the holy grail of sound, that amp went to a new owner. To my ears, the sound was kind of harsh for a tube amp, and lacking excitement. I agree that it is "a good-sounding DIY project." And, in that respect, if it does something to light the spark of interest in tube audio, then it has served a very useful purpose. Iain |
Velleman K40x0, the very model of an all-round amp
On Oct 21, 7:48 am, "Iain Churches" wrote:
"Andre Jute" wrote in message oups.com... On Oct 19, 12:11 am, "Iain Churches" wrote: The noise floor was exceptionally low. Later, a quick look on the bench revealed the noise floor to be 100µV, so a SNR of 105dB and at 96W, the THD was only 0.1% It depends on your outlook whether you view the Velleman K40x0 as that rare thing, a perfect all-round amp -- It's all opinion. Some opinions are informed by relevant experience and therefore more valuable. Some opinions are informed by nothing but street corner gossip or personal animosity and are therefore worthless. Oh,. I don't think it is anywhere near that! I regard it as a good-sounding DIY project, no more. The fact that the tube sockets are mounted on the PCB really put me off. I have a Radford STA 100. So no contest. And I have a Quad II. No contest, to my mind at least; it depends what you want to measure and hear. Except that the Quad II doesn't put out 100W. Let's compare apples with apples, not with gilded plums, mmm? I could compare the Velleman K4000 100W with a bunch of other kits I have built and used extensively: Arion Adonis PP 5581 20W, Audio Innovations Classic Stereo 25 PP EL34 25W, Triode Supply Japan Miyabe 300B SEPP 16W, etc, etc, and in no instance would it be comparing apples with apples, for the good and simple reason that none of them have 100W. In that the Velleman K40*0 stands alone, and gives the beginner versatility to use the most grossly insensitive bookshelf speakers to get real oomph on any music whatsoever. I could have chosen any of the amps listed, or any of the other kits I have built, including some I don't list because they have less than 10W, and said they're fine on some aspect (or even the best) but, while all of them have served me very well indeed, none of them can be put up against the Velleman without admitting some handicap in some perfectly common everyday use for an identifiable group of users. I might add that my favourite among that lot is the AI, which is a gentleman's amp, never intrusive; an amp you can play 14 hours every day and never find fault with. I find the Velleman far too analytical for my taste but that is because it is so accurate, a characteristic many value. But, to illustrate once more that all this is relative to usage and opinion, I play mainly chamber music at low volume; symphonic or other "big" music played on insensitive speakers *requires* a big amp. If I were into heavy metal or whatever the current fave of the loud set is called, I wouldn't touch any of my favourite amps for chamber music -- they'd all be less than convincing -- I'd go straight to the Velleman and acoustic overload heaven. By the way, the Velleman K40*0 is eminently tweakable. On my old netsite I had an entire big section devoted to altering the factory spec to make it sound like anything you wanted it to sound like. The "harshness" Jon Yaeger objects to, for instance, was just a matter of swapping out a ceramic (! now that's an excess of engineering...) cap for a film cap; you would of course sacrifice a little of the excellent noise spec (which was why the designer put it in there) but might consider the loss worthwhile to gain precisely the sound you want. I'm amazed that Yaeger doesn't know that. As for the snobbery of demanding point to point wiring on kits, go right ahead: you'll be helping to kill the hobby off faster than is necessary. In my experience eliminating the PCB, or insisting on sockets mounted to the chassis, just about triples the price of the kit, and ensures that the successful assembly rate is halved. (Suppliers who give a completion guarantee, or who provide a handholding service, keep very good records of these matters! Or you can read between the lines in the instructions and on the sites of those who sell PTP kits how fed up they are with seeing time and profits dribble away in support to eejits who cannot follow simple instructions.) If you insist on hardwiring, nothing stops you buying a Velleman K40*0 kit, or any other kit with a chassis, to get the design and all the parts, and simply drilling the cover to hold sockets for the tubes and then fitting the components to tag strips you supply. Nor is there any secret to designing a PCB construction properly for heat management: either ascertain that the kit has ceramic standoffs for power tubes and resistors as standard, or add them yourself. I'm really amazed at discovering DIYers who brag about their craftsmanship, then complain about an amp because it is designed to be built on a PCB: if you don't like it, change it! Iain For those who need or want a 100W and prefer tubes, the Velleman K40x0 is unique, zero competition that I know about. I don't see much point in nitpicking commercial amps against irrelevant self-proclaimed "standards"; the test is whether the thing works in the hands of owners, and the K40*0 worked fine for a decade and more in my hands. We've already had a bunch of clowns in this thread condemning one of the most succesful commercial amps in the world *without ever seeing one or hearing it*. That sort of street corner gossip repeated as gospel is what trashes the reputation of RAT, not putting down the thieves of intellectual rights or netbullies and netstalkers -- on the contrary, it is toleration and protection of such people that trashes our reputation. Andre Jute Visit Jute on Amps at http://members.lycos.co.uk/fiultra/ "wonderfully well written and reasoned information for the tube audio constructor" John Broskie TubeCAD & GlassWare "an unbelievably comprehensive web site containing vital gems of wisdom" Stuart Perry Hi-Fi News & Record Review |
Velleman K40x0, the very model of an all-round amp
"Andre Jute" wrote in message oups.com... On Oct 21, 7:48 am, "Iain Churches" wrote: "Andre Jute" wrote in message oups.com... On Oct 19, 12:11 am, "Iain Churches" wrote: The noise floor was exceptionally low. Later, a quick look on the bench revealed the noise floor to be 100µV, so a SNR of 105dB and at 96W, the THD was only 0.1% It depends on your outlook whether you view the Velleman K40x0 as that rare thing, a perfect all-round amp -- It's all opinion. Some opinions are informed by relevant experience and therefore more valuable. Some opinions are informed by nothing but street corner gossip or personal animosity and are therefore worthless. Oh,. I don't think it is anywhere near that! I regard it as a good-sounding DIY project, no more. The fact that the tube sockets are mounted on the PCB really put me off. I have a Radford STA 100. So no contest. And I have a Quad II. No contest, to my mind at least; it depends what you want to measure and hear. Except that the Quad II doesn't put out 100W. Let's compare apples with apples, not with gilded plums, mmm? I could compare the Velleman K4000 100W with a bunch of other kits I have built and used extensively: Arion Adonis PP 5581 20W, Audio Innovations Classic Stereo 25 PP EL34 25W, Triode Supply Japan Miyabe 300B SEPP 16W, etc, etc, and in no instance would it be comparing apples with apples, for the good and simple reason that none of them have 100W. In that the Velleman K40*0 stands alone, and gives the beginner versatility to use the most grossly insensitive bookshelf speakers to get real oomph on any music whatsoever. I could have chosen any of the amps listed, or any of the other kits I have built, including some I don't list because they have less than 10W, and said they're fine on some aspect (or even the best) but, while all of them have served me very well indeed, none of them can be put up against the Velleman without admitting some handicap in some perfectly common everyday use for an identifiable group of users. I might add that my favourite among that lot is the AI, which is a gentleman's amp, never intrusive; an amp you can play 14 hours every day and never find fault with. I find the Velleman far too analytical for my taste but that is because it is so accurate, a characteristic many value. But, to illustrate once more that all this is relative to usage and opinion, I play mainly chamber music at low volume; symphonic or other "big" music played on insensitive speakers *requires* a big amp. If I were into heavy metal or whatever the current fave of the loud set is called, I wouldn't touch any of my favourite amps for chamber music -- they'd all be less than convincing -- I'd go straight to the Velleman and acoustic overload heaven. By the way, the Velleman K40*0 is eminently tweakable. On my old netsite I had an entire big section devoted to altering the factory spec to make it sound like anything you wanted it to sound like. The "harshness" Jon Yaeger objects to, for instance, was just a matter of swapping out a ceramic (! now that's an excess of engineering...) cap for a film cap; you would of course sacrifice a little of the excellent noise spec (which was why the designer put it in there) but might consider the loss worthwhile to gain precisely the sound you want. I'm amazed that Yaeger doesn't know that. As for the snobbery of demanding point to point wiring on kits, go right ahead: you'll be helping to kill the hobby off faster than is necessary. In my experience eliminating the PCB, or insisting on sockets mounted to the chassis, just about triples the price of the kit, and ensures that the successful assembly rate is halved. (Suppliers who give a completion guarantee, or who provide a handholding service, keep very good records of these matters! Or you can read between the lines in the instructions and on the sites of those who sell PTP kits how fed up they are with seeing time and profits dribble away in support to eejits who cannot follow simple instructions.) If you insist on hardwiring, nothing stops you buying a Velleman K40*0 kit, or any other kit with a chassis, to get the design and all the parts, and simply drilling the cover to hold sockets for the tubes and then fitting the components to tag strips you supply. Nor is there any secret to designing a PCB construction properly for heat management: either ascertain that the kit has ceramic standoffs for power tubes and resistors as standard, or add them yourself. I'm really amazed at discovering DIYers who brag about their craftsmanship, then complain about an amp because it is designed to be built on a PCB: if you don't like it, change it! Iain For those who need or want a 100W and prefer tubes, the Velleman K40x0 is unique, zero competition that I know about. I don't see much point in nitpicking commercial amps against irrelevant self-proclaimed "standards"; the test is whether the thing works in the hands of owners, and the K40*0 worked fine for a decade and more in my hands. We've already had a bunch of clowns in this thread condemning one of the most succesful commercial amps in the world *without ever seeing one or hearing it*. That sort of street corner gossip repeated as gospel is what trashes the reputation of RAT, not putting down the thieves of intellectual rights or netbullies and netstalkers -- on the contrary, it is toleration and protection of such people that trashes our reputation. Horse****, Andre. It isn't the reputation of RAT that's trashed, it's the atmosphere that people have been fleeing. That atmosphere has been trashed by your relentless personal attacks on everyone you can find even the slightest reason to go after. But it's OK; pretty soon you and your sock puppets will have this place all to yourselves. You'll be able to launch devastating attacks on your sock puppets every day and no one will complain unless you do it for them. He he, Andre, what a horse's ass you are. Andre Jute Visit Jute on Amps at http://members.lycos.co.uk/fiultra/ "wonderfully well written and reasoned information for the tube audio constructor" John Broskie TubeCAD & GlassWare "an unbelievably comprehensive web site containing vital gems of wisdom" Stuart Perry Hi-Fi News & Record Review |
Velleman K40x0, the very model of an all-round amp
I don't see much point in nitpicking commercial amps against irrelevant self-proclaimed "standards"; the test is whether the thing works in the hands of owners, and the K40*0 worked fine for a decade and more in my hands. We've already had a bunch of clowns in this thread condemning one of the most succesful commercial amps in the world *without ever seeing one or hearing it*. That sort of street corner gossip repeated as gospel is what trashes the reputation of RAT, not putting down the thieves of intellectual rights or netbullies and netstalkers -- on the contrary, it is toleration and protection of such people that trashes our reputation. Andre Jute I'll second Phread, it is the personal attacking that makes this place less-than. If you'd examine the history, RAT was a reasonable going concern until the Jute v. Magnetquest war. Seems Andre was unable to make a legitimate criticism of Mikey stick. So then Andre, you mention an AB amp having A power, you reference an 80W SE amp, claim an off the rack Vellman kit is brilliant, and then attack anybody who'd have the guts to say you've over reached. Even with poor S/N ratio there is still signal. Let's see some from you. cheers, Douglas |
Velleman K40x0, the very model of an all-round amp
On Mon, 22 Oct 2007 13:50:47 -0700, Multi-grid wrote:
snip So then Andre, you mention an AB amp having A power, you reference an 80W SE amp, claim an off the rack Vellman kit is brilliant, and then attack anybody who'd have the guts to say you've over reached. Even with poor S/N ratio there is still signal. Let's see some from you. cheers, Surely though, a class AB amp such as the Vellman *is* running in class A up to the point where one output device starts to turn off isn't it? The changeover to class B happens at that point and is dependent on the quiescent current in the outputs. A true class A amp is only a special case of the normal AB class. It's just that it clips symmetrically instead of moving smoothly into class B. ;-) -- Mick (Working in a M$-free zone!) Web: http://www.nascom.info http://mixpix.batcave.net |
Velleman K40x0, the very model of an all-round amp
Surely though, a class AB amp such as the Vellman *is* running in class A up to the point where one output device starts to turn off isn't it? -- Mick (Working in a M$-free zone!) Web:http://www.nascom.info http://mixpix.batcave.net Nope, not a chance. That both tubes are conducting does not mean it is A. Have some respect...:) AB amps don't have any A power, that is why there is a seperate classification. cheers, Douglas |
Output classes A and AB
On Oct 22, 2:33 pm, mick wrote:
On Mon, 22 Oct 2007 13:50:47 -0700, Multi-grid wrote: snip So then Andre, you mention an AB amp having A power, you reference an 80W SE amp, claim an off the rack Vellman kit is brilliant, and then attack anybody who'd have the guts to say you've over reached. Even with poor S/N ratio there is still signal. Let's see some from you. cheers, Who is this fellow "Multi-grid", and why is he addressing me? Surely though, a class AB amp such as the Vellman *is* running in class A up to the point where one output device starts to turn off isn't it? The changeover to class B happens at that point and is dependent on the quiescent current in the outputs. I would have thought anyone with a handle like "Multi-grid" would have taken that sort of basic tube knowledge from the teat. Mind you, I remember when Ron Bales wanted us here on RAT to give everyone who claimed a "tubie-handle" a test of tube knowledge to ensure they don't give a respectable hobby a bad name by wielding their ignorance like clubs. That was about 1998. Looks like this "Multi-grid" fellow is a prime candidate for the Bales Test. A true class A amp is only a special case of the normal AB class. It's just that it clips symmetrically instead of moving smoothly into class B. ;-) It is beneath my dignity to rise to such provocation -- sniff. A Class AB amp is a compromised Class A amp, and it probably requires negative feedback too to work even acceptably. A properly designed Class A amp never clips because the operating parameters were so chosen that it runs out of signal from the intended source before it can clip (that is one reason why the design instructions on my netsite feature the *design center* process so heavily). It is only "engineers" who "design" amps to hog the maximum power from each tube who even need a concept like clipping; for sane tubies it is obsolete terminology. -- Mick (Working in a M$-free zone!) Web:http://www.nascom.infohttp://mixpix.batcave.net Andre Jute Our legislators managed to criminalize fox-hunting and smoking; when will they get off their collective fat backside and criminalize negative feedback? It is clearly consumed only by thickoes. |
Output classes A and AB
A properly designed Class A amp
never clips because the operating parameters were so chosen that it runs out of signal from the intended source before it can clip (that is one reason why the design instructions on my netsite feature the *design center* process so heavily). Stay on topic please. While you're at it, please refrain from making personal attacks, it is beneath you( I hope ). Class A has nothing to do with its input signal. The finals clip symetrically. Or perhaps unsymetrically if it is power limited A, so to say overbiased given the load and B+. If you have plate dissipation to spare, it is certainly possible. Matter of fact I am listening to one such amp now...:) cheers, Douglas |
Output classes A and AB
Multi-grid wrote: A properly designed Class A amp never clips because the operating parameters were so chosen that it runs out of signal from the intended source before it can clip (that is one reason why the design instructions on my netsite feature the *design center* process so heavily). Stay on topic please. While you're at it, please refrain from making personal attacks, it is beneath you( I hope ). Class A has nothing to do with its input signal. The finals clip symetrically. Or perhaps unsymetrically if it is power limited A, so to say overbiased given the load and B+. If you have plate dissipation to spare, it is certainly possible. Matter of fact I am listening to one such amp now...:) cheers, Douglas I believe the point it changes from 'class A' to 'class AB' is commonly accepted to be the point where the output stage begins to draw more current from the power supply. By commonly accepted, I mean I've read a ton of magazine reviews of tube amps where they use this logic, stated almost exactly as Andre has used it. In other words, the amp is biased a bit hotter than class B, and this lowers low level distortion a bit at the expense of peak power output. Stating that "the amplifier is Class A until XXX watts", really, is telling you how hot the tubes are biased relative to the two extremes of pure class A (full dissapation), and pure class (cut off). |
Output classes A and AB
In article . com,
Andre Jute wrote: On Oct 22, 2:33 pm, mick wrote: On Mon, 22 Oct 2007 13:50:47 -0700, Multi-grid wrote: snip So then Andre, you mention an AB amp having A power, you reference an 80W SE amp, claim an off the rack Vellman kit is brilliant, and then attack anybody who'd have the guts to say you've over reached. Even with poor S/N ratio there is still signal. Let's see some from you. cheers, Who is this fellow "Multi-grid", and why is he addressing me? Hi Andre, This fellow "Multi-grid" is either a Troll, ignorant, or most likely both, his goal appears to be trying to stir up trouble so he is best ignored. Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/ |
Output classes A and AB
On Oct 23, 6:01 am, maxhifi wrote:
Multi-grid wrote: A properly designed Class A amp never clips because the operating parameters were so chosen that it runs out of signal from the intended source before it can clip (that is one reason why the design instructions on my netsite feature the *design center* process so heavily). Stay on topic please. While you're at it, please refrain from making personal attacks, it is beneath you( I hope ). Class A has nothing to do with its input signal. The finals clip symetrically. Or perhaps unsymetrically if it is power limited A, so to say overbiased given the load and B+. If you have plate dissipation to spare, it is certainly possible. Matter of fact I am listening to one such amp now...:) cheers, Douglas I believe the point it changes from 'class A' to 'class AB' is commonly accepted to be the point where the output stage begins to draw more current from the power supply. By commonly accepted, I mean I've read a ton of magazine reviews of tube amps where they use this logic, stated almost exactly as Andre has used it. In other words, the amp is biased a bit hotter than class B, and this lowers low level distortion a bit at the expense of peak power output. Stating that "the amplifier is Class A until XXX watts", really, is telling you how hot the tubes are biased relative to the two extremes of pure class A (full dissapation), and pure class (cut off).- Hide quoted text - - Show quoted text - Class A has nothing to do with dissipation either. Just because some marketing group noticed that class A means something good, does not make it right either. Just because it seems to make sense is no reason to *******ize the definition. Find some other way to describe it. cheers, Douglas |
Output classes A and AB
On Oct 23, 6:33 am, John Byrns wrote:
In article . com, Andre Jute wrote: On Oct 22, 2:33 pm, mick wrote: On Mon, 22 Oct 2007 13:50:47 -0700, Multi-grid wrote: snip So then Andre, you mention an AB amp having A power, you reference an 80W SE amp, claim an off the rack Vellman kit is brilliant, and then attack anybody who'd have the guts to say you've over reached. Even with poor S/N ratio there is still signal. Let's see some from you. cheers, Who is this fellow "Multi-grid", and why is he addressing me? Hi Andre, This fellow "Multi-grid" is either a Troll, ignorant, or most likely both, his goal appears to be trying to stir up trouble so he is best ignored. Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/ It appears you folks are living up to your reputation for making personal attacks. It isn't this: That sort of street corner gossip repeated as gospel is what trashes the reputation of RAT, not putting down the thieves of intellectual rights or netbullies and netstalkers -- on the contrary, it is toleration and protection of such people that trashes our reputation. that's doing RAT harm. Getting nasty on the other hand... cheers, Douglas |
Output classes A and AB
On Oct 22, 11:33 pm, John Byrns wrote:
This fellow "Multi-grid" is either a Troll, ignorant, or most likely both, his goal appears to be trying to stir up trouble so he is best ignored. Ever ready with the diaper, John? Peter Wieck Wyncote, PA |
Output classes A and AB
Multi-grid wrote: maxhifi wrote: Stating that "the amplifier is Class A until XXX watts", really, is telling you how hot the tubes are biased relative to the two extremes of pure class A (full dissapation), and pure class (cut off).- Hide quoted text - Class A has nothing to do with dissipation either. Just because some marketing group noticed that class A means something good, does not make it right either. Just because it seems to make sense is no reason to *******ize the definition. Find some other way to describe it. The definition of Class A is very simple. It requires that the output device(s) never cease conducting under any signal condition. Graham |
Output classes A and AB
On Tue, 23 Oct 2007 14:34:31 +0100, Eeyore wrote:
Multi-grid wrote: maxhifi wrote: Stating that "the amplifier is Class A until XXX watts", really, is telling you how hot the tubes are biased relative to the two extremes of pure class A (full dissapation), and pure class (cut off).- Hide quoted text - Class A has nothing to do with dissipation either. Just because some marketing group noticed that class A means something good, does not make it right either. Just because it seems to make sense is no reason to *******ize the definition. Find some other way to describe it. The definition of Class A is very simple. It requires that the output device(s) never cease conducting under any signal condition. Correct. A class AB amp fulfills this up to the point where one side starts to turn off. -- Mick (Working in a M$-free zone!) Web: http://www.nascom.info http://mixpix.batcave.net |
Output classes A and AB
Multi-grid wrote: Class A has nothing to do with dissipation either. Then Poopie wrote: The definition of Class A is very simple. It requires that the output device(s) never cease conducting under any signal condition. Then Mick http://www.nascom.info and http://mixpix.batcave.net wrote: Correct. A class AB amp fulfills this up to the point where one side starts to turn off. I can see what you're getting at, Poopie, and so can Mick apparently, but I don't think I want to wear your definition where it says "under any signal condition". That's most misleading, especially with a newbie on the board who stubbornly keeps claiming signal has nothing to do with Class A. Any power stage that is hitherto Class A can driven to cutoff by simply increasing the signal until the output cuts out at either zero current or zero voltage. In any and all cases, Class A is defined, though usually implicitly rather than explcitly, as at a particular, *limited* signal voltage. I therefore prefer the definition of Class A which says simply: ***Class A operating conditions do not permit the output device to cease conducting.*** If you insist on describing the signal condition, you could add the words *at the design or intended or specified signal*. As for Dougles Multi-grid's silly insistence that signal and dissipation have nothing to do with Class A operation, thanks for the giggle, sonny, but you'd better hit the books lots more before you seek entry to this club. In particular, you should pay attention to this, which often comes as a bolt from the blue to repair hacks like you, who tend to assume that the parameters are godgiven and fixed: the *designer* chooses the plate voltage and negative bias, that sets the current at quiescence, through which the designer then runs the loadline at a particular angle when he chooses a primary impedance for his output transformer, the slope of the loadline determining how far the quiescent point is from current cutoff (or voltage cutoff...), and that in turn defines the signal voltage that can be put in for Class A operation, which in turn defines the output power. Thus the signal level has everything to do with Class A operation, and in turn defines maximum possible dissipation from Class A operation. Cruise my netsite; all this is explained in both words and pictures. Andre Jute Visit Jute on Amps at http://members.lycos.co.uk/fiultra/ "wonderfully well written and reasoned information for the tube audio constructor" John Broskie TubeCAD & GlassWare "an unbelievably comprehensive web site containing vital gems of wisdom" Stuart Perry Hi-Fi News & Record Review |
Output classes A and AB
On Oct 23, 3:37 pm, Andre Jute wrote:
Multi-grid wrote: Class A has nothing to do with dissipation either. Then Poopie wrote: The definition of Class A is very simple. It requires that the output device(s) never cease conducting under any signal condition. Then Mickhttp://www.nascom.infoandhttp://mixpix.batcave.netwrote: Correct. A class AB amp fulfills this up to the point where one side starts to turn off. I can see what you're getting at, Poopie, and so can Mick apparently, but I don't think I want to wear your definition where it says "under any signal condition". That's most misleading, especially with a newbie on the board who stubbornly keeps claiming signal has nothing to do with Class A. Any power stage that is hitherto Class A can driven to cutoff by simply increasing the signal until the output cuts out at either zero current or zero voltage. In any and all cases, Class A is defined, though usually implicitly rather than explcitly, as at a particular, *limited* signal voltage. I therefore prefer the definition of Class A which says simply: ***Class A operating conditions do not permit the output device to cease conducting.*** If you insist on describing the signal condition, you could add the words *at the design or intended or specified signal*. As for Dougles Multi-grid's silly insistence that signal and dissipation have nothing to do with Class A operation, thanks for the giggle, sonny, but you'd better hit the books lots more before you seek entry to this club. In particular, you should pay attention to this, which often comes as a bolt from the blue to repair hacks like you, who tend to assume that the parameters are godgiven and fixed: the *designer* chooses the plate voltage and negative bias, that sets the current at quiescence, through which the designer then runs the loadline at a particular angle when he chooses a primary impedance for his output transformer, the slope of the loadline determining how far the quiescent point is from current cutoff (or voltage cutoff...), and that in turn defines the signal voltage that can be put in for Class A operation, which in turn defines the output power. Thus the signal level has everything to do with Class A operation, and in turn defines maximum possible dissipation from Class A operation. Cruise my netsite; all this is explained in both words and pictures. Mmm. It occurs to me that when dealing with a newbie, even if it is all explained on my netsite, and Patrick's, and all the textbooks, and in Crowhurst, which Multi-grid could read with profit, I should explain what signal voltage has to do with power output. Power is the product of voltage and current. The bigger the voltage and current swing, the greater the power output (for a given load). The plate voltage and current swing is proportional to the size of the signal working through mu, the amplification factor of the tube. Thus the greater the signal that can be put in under a particular class of operation, in this case Class A, the greater the voltage swing and the more the current change between the peaks of the signal, the bigger the product of voltage and current, and the greater the power. So, you see, sonny, in Class A operation, which is in any event very inefficient, the amount of space the designer allows for signal to swing without breaching Class A conditions determines the entire outcome. The same applies to Class AB, where the signal-travel the designer has arranged (by his choice of plate voltage and negative grid bias and primary impedance) during which current is not cut off determines how much of the output can be in Class A, with the rest by definition in Class B. Andre Jute Visit Jute on Amps athttp://members.lycos.co.uk/fiultra/ "wonderfully well written and reasoned information for the tube audio constructor" John Broskie TubeCAD & GlassWare "an unbelievably comprehensive web site containing vital gems of wisdom" Stuart Perry Hi-Fi News & Record Review |
Output classes A and AB
On Oct 24, 2:56 am, Andre Jute wrote:
On Oct 23, 3:37 pm, Andre Jute wrote: Multi-grid wrote: Class A has nothing to do with dissipation either. Then Poopie wrote: The definition of Class A is very simple. It requires that the output device(s) never cease conducting under any signal condition. Then Mickhttp://www.nascom.infoandhttp://mixpix.batcave.netwrote: Correct. A class AB amp fulfills this up to the point where one side starts to turn off. I can see what you're getting at, Poopie, and so can Mick apparently, but I don't think I want to wear your definition where it says "under any signal condition". That's most misleading, especially with a newbie on the board who stubbornly keeps claiming signal has nothing to do with Class A. Any power stage that is hitherto Class A can driven to cutoff by simply increasing the signal until the output cuts out at either zero current or zero voltage. In any and all cases, Class A is defined, though usually implicitly rather than explcitly, as at a particular, *limited* signal voltage. I therefore prefer the definition of Class A which says simply: ***Class A operating conditions do not permit the output device to cease conducting.*** If you insist on describing the signal condition, you could add the words *at the design or intended or specified signal*. As for Dougles Multi-grid's silly insistence that signal and dissipation have nothing to do with Class A operation, thanks for the giggle, sonny, but you'd better hit the books lots more before you seek entry to this club. In particular, you should pay attention to this, which often comes as a bolt from the blue to repair hacks like you, who tend to assume that the parameters are godgiven and fixed: the *designer* chooses the plate voltage and negative bias, that sets the current at quiescence, through which the designer then runs the loadline at a particular angle when he chooses a primary impedance for his output transformer, the slope of the loadline determining how far the quiescent point is from current cutoff (or voltage cutoff...), and that in turn defines the signal voltage that can be put in for Class A operation, which in turn defines the output power. Thus the signal level has everything to do with Class A operation, and in turn defines maximum possible dissipation from Class A operation. Cruise my netsite; all this is explained in both words and pictures. Mmm. It occurs to me that when dealing with a newbie, even if it is all explained on my netsite, and Patrick's, and all the textbooks, and in Crowhurst, which Multi-grid could read with profit, I should explain what signal voltage has to do with power output. Power is the product of voltage and current. The bigger the voltage and current swing, the greater the power output (for a given load). The plate voltage and current swing is proportional to the size of the signal working through mu, the amplification factor of the tube. Thus the greater the signal that can be put in under a particular class of operation, in this case Class A, the greater the voltage swing and the more the current change between the peaks of the signal, the bigger the product of voltage and current, and the greater the power. So, you see, sonny, in Class A operation, which is in any event very inefficient, the amount of space the designer allows for signal to swing without breaching Class A conditions determines the entire outcome. The same applies to Class AB, where the signal-travel the designer has arranged (by his choice of plate voltage and negative grid bias and primary impedance) during which current is not cut off determines how much of the output can be in Class A, with the rest by definition in Class B. Andre Jute Visit Jute on Amps athttp://members.lycos.co.uk/fiultra/ "wonderfully well written and reasoned information for the tube audio constructor" John Broskie TubeCAD & GlassWare "an unbelievably comprehensive web site containing vital gems of wisdom" Stuart Perry Hi-Fi News & Record Review- Hide quoted text - - Show quoted text -- Hide quoted text - - Show quoted text - keep repeating yourself, it may come true sometime. In the meantime, some additional proof besides the circular stuff you keep digging up might show you the holes in your arguement. As to Crowhurst, his creativity outstripped his ability to write unequivocally. While you're digging, why not produce some documentation of the 80W SE amp you mentioned earlier. cheers, Douglas |
Output classes A and AB
On Oct 24, 1:37 am, Andre Jute wrote:
Multi-grid wrote: Class A has nothing to do with dissipation either. Then Poopie wrote: The definition of Class A is very simple. It requires that the output device(s) never cease conducting under any signal condition. Then Mickhttp://www.nascom.infoandhttp://mixpix.batcave.netwrote: Correct. A class AB amp fulfills this up to the point where one side starts to turn off. I can see what you're getting at, Poopie, and so can Mick apparently, but I don't think I want to wear your definition where it says "under any signal condition". That's most misleading, especially with a newbie on the board who stubbornly keeps claiming signal has nothing to do with Class A. Any power stage that is hitherto Class A can driven to cutoff by simply increasing the signal until the output cuts out at either zero current or zero voltage. In any and all cases, Class A is defined, though usually implicitly rather than explcitly, as at a particular, *limited* signal voltage. I therefore prefer the definition of Class A which says simply: ***Class A operating conditions do not permit the output device to cease conducting.*** If you insist on describing the signal condition, you could add the words *at the design or intended or specified signal*. As for Dougles Multi-grid's silly insistence that signal and dissipation have nothing to do with Class A operation, thanks for the giggle, sonny, but you'd better hit the books lots more before you seek entry to this club. They don't Andre, no matter how much you claim they do. Class A, is as simple as you first stated it: ***Class A operating conditions do not permit the output device to cease conducting.*** It should get the addition that remote cut off behaviour is not included. In particular, you should pay attention to this, which often comes as a bolt from the blue to repair hacks like you, who tend to assume that the parameters are godgiven and fixed: the *designer* chooses the plate voltage and negative bias, that sets the current at quiescence, through which the designer then runs the loadline at a particular angle when he chooses a primary impedance for his output transformer, the slope of the loadline determining how far the quiescent point is from current cutoff (or voltage cutoff...), and that in turn defines the signal voltage that can be put in for Class A operation, which in turn defines the output power. Thus the signal level has everything to do with Class A operation, and in turn defines maximum possible dissipation from Class A operation. Cruise my netsite; all this is explained in both words and pictures. I make no such assumptions. That you'd think I would only shows your limitations. Stay off this group-killing personal attacking if you please. Isn't one war named after you enough? cheers, Douglas |
Output classes A and AB
In article . com,
Multi-grid wrote: On Oct 24, 1:37 am, Andre Jute wrote: As for Dougles Multi-grid's silly insistence that signal and dissipation have nothing to do with Class A operation, thanks for the giggle, sonny, but you'd better hit the books lots more before you seek entry to this club. They don't Andre, no matter how much you claim they do. Class A, is as simple as you first stated it: ***Class A operating conditions do not permit the output device to cease conducting.*** Precisely, that is why when the operating conditions of a class AB amplifier are restricted by limiting the applied input voltage the amplifier is able to put out class A power at a level that is lower than the maximum available class AB power. It should get the addition that remote cut off behaviour is not included. Most real world tubes display remote cut off behaviour as the plate curves become distinctly compressed in the high voltage low current quadrant. I guess that rules out the possibility of any tube amplifier operating class A. Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/ |
Output classes A and AB
On Oct 23, 8:51 pm, John Byrns wrote:
In article . com, Multi-grid wrote: On Oct 24, 1:37 am, Andre Jute wrote: As for Dougles Multi-grid's silly insistence that signal and dissipation have nothing to do with Class A operation, thanks for the giggle, sonny, but you'd better hit the books lots more before you seek entry to this club. They don't Andre, no matter how much you claim they do. Class A, is as simple as you first stated it: ***Class A operating conditions do not permit the output device to cease conducting.*** Precisely, that is why when the operating conditions of a class AB amplifier are restricted by limiting the applied input voltage the amplifier is able to put out class A power at a level that is lower than the maximum available class AB power. It should get the addition that remote cut off behaviour is not included. Most real world tubes display remote cut off behaviour as the plate curves become distinctly compressed in the high voltage low current quadrant. I guess that rules out the possibility of any tube amplifier operating class A. John, with respect: Andre is out of his depth on this one. And his typical response to being out of his depth is to repeat, attack, repeat, attack, and then repeat again. But none of that makes what he states true or correct. And as your life's work is somewhere between cleaning up after him, powdering him and changing his diapers and seeking exceptions and outliers, I am not surprised that you are joining this discussion as per usual. There have actually been some reasonable discussions on tube lore lately - those from which Andre has stayed away. And, were he to refrain from delivering (typically incorrect) absolutes he might even be capable of intiating and even participating in such discussions. But, it is very hard for a pretender to stick to what he knows and for a poseur to pronounce with less than "papal" infallibility. Which makes Andre little more than a charlatan and never-was with delusions of adequacy. All-and-at-the-same-time, he is a big boy of some 60+ summers and well able to manage his own affairs and discussions... or it would be so were he mature enough to understand. Infants usually and eventually become potty-trained. And that is the essential difference between Andre and an infant, and why your efforts at clean up after him are futile. He will never change however heroic your efforts. If you want an analogy, GM, some time back had a V8 engine that *could* fire on 4, 6, or 8 cylinders depending on load conditions. But it was never "other than" a V8, nor could any amount of wishful thinking or closely held beliefs make it "other than" a V8. Peter Wieck Wyncote, PA |
Output classes A and AB
Multi-grid wrote: On Oct 23, 6:01 am, maxhifi wrote: Multi-grid wrote: A properly designed Class A amp never clips because the operating parameters were so chosen that it runs out of signal from the intended source before it can clip (that is one reason why the design instructions on my netsite feature the *design center* process so heavily). Stay on topic please. While you're at it, please refrain from making personal attacks, it is beneath you( I hope ). Class A has nothing to do with its input signal. The finals clip symetrically. Or perhaps unsymetrically if it is power limited A, so to say overbiased given the load and B+. If you have plate dissipation to spare, it is certainly possible. Matter of fact I am listening to one such amp now...:) cheers, Douglas I believe the point it changes from 'class A' to 'class AB' is commonly accepted to be the point where the output stage begins to draw more current from the power supply. By commonly accepted, I mean I've read a ton of magazine reviews of tube amps where they use this logic, stated almost exactly as Andre has used it. In other words, the amp is biased a bit hotter than class B, and this lowers low level distortion a bit at the expense of peak power output. Stating that "the amplifier is Class A until XXX watts", really, is telling you how hot the tubes are biased relative to the two extremes of pure class A (full dissapation), and pure class (cut off).- Hide quoted text - - Show quoted text - Class A has nothing to do with dissipation either. Class A has everything to do with dissipation!!!! But lets begin with class B. In class B, there is ZERO anode dissipation because the tubes ( or SS devices ) are biased at cut off. The amplifier only has device dissipation when signal flows. But distortion is notoriously high, and to avoid the worst of it, class AB is used where the tubes/devices are biased with idle dissipation well below the maximum allowable fpr the tube or device. This allows a small amount of pure class A working power until cut off begins to occur in tubes/devices on each alternate wave peak. Hence a pair of KT88 might be set up with Ea = 600V, and Ia at idle of 30mA, for a Pda at idle of 18 watts. Maximum allowable for a single KT88 is 42 watts. The AB power avaliable with 600V is around 100Watts class AB but the pure class A might be less than 10 watts for the load where 100Watts AB is possible, which will be a load a lot less than the load required for pure class A operation up to clipping. Its possible to have two KT88 dissipating a total of 36 watts, Ea = 600V, and have a load which ensures all the power is class A. It is a high ohm load, but achievable if you connect a 16 ohm speaker to an AB amp with an outlet for 4 ohms; the reflected anode load of say 5k becomes 20k. And the beam terode class A efficiency will be up to about 45% and so you'll get a maximum of 16.2 watts of pure class A power from a pair of KT88 with a total of 36 watts Pda. If the Pda is raised to 72 watts for the pair by doubling the Ia, then max class A also doubles if efficiency is constant, so 36 watts is possible. The load can be a lot lower as well. I suggest you learn much more about basic output tube behaviour before you shoot your mouth off by saying that " Class A has nothing to do with dissipation either. " Just because some marketing group noticed that class A means something good, does not make it right either. Just because it seems to make sense is no reason to *******ize the definition. Find some other way to describe it. cheers, Douglas You are looking like the one *******izing something imho. Please clarify your reasons for whatever your stance really is. Patrick Turner. |
Output classes A and AB
Eeyore wrote: Multi-grid wrote: maxhifi wrote: Stating that "the amplifier is Class A until XXX watts", really, is telling you how hot the tubes are biased relative to the two extremes of pure class A (full dissapation), and pure class (cut off).- Hide quoted text - Class A has nothing to do with dissipation either. Just because some marketing group noticed that class A means something good, does not make it right either. Just because it seems to make sense is no reason to *******ize the definition. Find some other way to describe it. The definition of Class A is very simple. It requires that the output device(s) never cease conducting under any signal condition. It means slightly more than this because tubes don't cut off as sharply as other devices. So class A means where PP power tubes do not have Ia on either side of the PP circuit ever having Ia fall below 10% of the idle value. Below about 10% of the idle value, the cut off behaviour becomes substantially non linear, as opposed to substantially linear prior to cut off. Gradual cut off in triodes makes them particularly nice to use in AB amps. Minimal switching artifacts are generated. And the gm rises with Ia, so the load change reduction happening after cut off of one tube means the triode compensates for the sudden drop in gain you see in pentodes and beam tubes. Its the internal triode NFB at work to give the low Ra. And if the first 1/2 of output power maximum is class A by my definition, then is its deemed A, and the remaining 1/2 is B, and the total action is AB. Most ppl will not hear any difference if the bias is increased to ensure all power up to clipping is pure class A. The load experienced by one of the tubes in an AB PP pair is NOT a straight line load as one would draw across the anode curves of a given tube. While in class A, each tube sees an almost straight line load, but always of slightly different ohm value because the gm of each tube isn't the same. But the RL for each tube while in class A is approximately 1/2 of RLa-a.1 Once cut off has begun in earnest during each wave cycle, the load each tube sees become its "class B load" = 1/4 RLa-a, and one has to draw a CURVED LOAD LINE to describe the loading of each PP output tube to describe what each is really doing. The load of one tube is affected by the load on the other until cut off happens, and then each tube is on its own to deal with the load of 1/4 RLa-a. Patrick Turner. Graham |
Output classes A and AB
Class A, is as simple as you first stated it: ***Class A operating conditions do not permit the output device to cease conducting.*** It should get the addition that remote cut off behaviour is not included. . Isn't one war named after you enough? - Show quoted text - sorry about that, forgot one thing...That is *AT FULL POWER*, if one gets cut off before that, it is AB, which is neither A nor B. cheers, Douglas |
Output classes A and AB
I suggest you learn much more about basic output tube behaviour before you shoot your mouth off by saying that " Class A has nothing to do with dissipation either. " - Show quoted text - The dissipation is only related to the output power. A Class A amp does not need a particular fraction of plate dissipation to be used in order to classify as A. Examples are not needed, symbolic notation will be fine. The amp is defined by its behaviour. The bias that goes from 360- degree conduction to something closer to 180 gets labled AB. Iff it can maintain 360 degree conduction it gets the A. Since it's usually quality over max power choices that run to class A designs, the marketers decide to appropriate it for their own in AB designs. You remember the advertisements general content( reference Andre's comments on the Vellman ). B is supposedly 180 degree, but given cut-off bunching, none are that small. Why not have this discussion about the differences between AB and B? cheers, Douglas |
Output classes A and AB
Patrick Turner wrote: Eeyore wrote: Multi-grid wrote: maxhifi wrote: Stating that "the amplifier is Class A until XXX watts", really, is telling you how hot the tubes are biased relative to the two extremes of pure class A (full dissapation), and pure class (cut off).- Hide quoted text - Class A has nothing to do with dissipation either. Just because some marketing group noticed that class A means something good, does not make it right either. Just because it seems to make sense is no reason to *******ize the definition. Find some other way to describe it. The definition of Class A is very simple. It requires that the output device(s) never cease conducting under any signal condition. It means slightly more than this because tubes don't cut off as sharply as other devices. I see what you're saying but I do believe that the definition is unchanged. Obviously avoiding any region of significant non-linearity is preferable but that in its own right doesn't change the definition. Graham |
Output classes A and AB
In article .com,
Peter Wieck wrote: On Oct 23, 8:51 pm, John Byrns wrote: In article . com, Multi-grid wrote: ***Class A operating conditions do not permit the output device to cease conducting.*** Precisely, that is why when the operating conditions of a class AB amplifier are restricted by limiting the applied input voltage the amplifier is able to put out class A power at a level that is lower than the maximum available class AB power. John, with respect: Andre is out of his depth on this one. Peter, I know you are obsessed with Andre, but this is not about Andre, it is about Multi-grid's silly statement that a class AB amplifier can't put out a limited amount of "class A power". Multi-grid is confusing the definition of a PP amplifier's class with it's ability to deliver some amount of power, less than rated output, without either output tube cutting off. It has been common usage for as long as I can remember to call this "class A power" because at this power level both output tubes are conducting over the full 360 degree cycle, as in a class A amplifier. An amplifiers class is determined by the operation of the tubes at the rated power output, however in the case of a class AB amplifier, a lesser amount of "class A power" is available. To illustrate how silly Multigrid's claim is, consider a class AB amplifier with a rated output of 50 Watts in class AB. Further suppose this amplifier is capable of putting out 15 Watts without either output tube cutting off, 15 Watts of what Andre, and many other famous amplifier designers, call "class A power". Now we all agree that this is a class AB amplifier, but suppose we connect a suitable network of Zener and ordinary diodes across the primary of the output transformer which clamp the maximum output voltage at the level necessary to produce an output of 15 Watts. Has this amplifier now become a class A amplifier simply because we have placed this clamp circuit across the primary of the output transformer? If we test it with our sine wave generator and oscilloscope we are going to conclude that it is a class A amplifier because both tubes are still conducting over the full 360 degree cycle at the point of clipping. I leave the implications of this experiment for the student to consider. Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/ |
Output classes A and AB
On Oct 24, 6:57 am, flipper wrote:
On Wed, 24 Oct 2007 13:44:13 +0100, Eeyore wrote: Patrick Turner wrote: Eeyore wrote: Multi-grid wrote: maxhifi wrote: Stating that "the amplifier is Class A until XXX watts", really, is telling you how hot the tubes are biased relative to the two extremes of pure class A (full dissapation), and pure class (cut off).- Hide quoted text - Class A has nothing to do with dissipation either. Just because some marketing group noticed that class A means something good, does not make it right either. Just because it seems to make sense is no reason to *******ize the definition. Find some other way to describe it. The definition of Class A is very simple. It requires that the output device(s) never cease conducting under any signal condition. It means slightly more than this because tubes don't cut off as sharply as other devices. I see what you're saying but I do believe that the definition is unchanged. Obviously avoiding any region of significant non-linearity is preferable but that in its own right doesn't change the definition. People are talking semantically past each other with some speaking of the definition of the 'amplifier' class while others are speaking of it's behavior under a restricted set of operating conditions; and it is useful to observe that under an appropriately restricted set of conditions the output tubes conduct 360 degrees as in 'Class A' operation. "Useful", indeed, Flipper. Thanks. But I would go further and say that the signal and dissipation restriction is part of the definition, as you go on to imply: For example, if maximum power, or efficiency, were the primary concern then one might bias more to the 'B' side of the equation while if fidelity were the primary concern one might bias more to the 'A'. Precisely. Both Class A operation and Class B operation are inherent in the nomenclature and definition and their relative importance is clearly intended to be in the designer's discretion. Historically, the original purpose of Class AB was to annihilate the second harmonic which before made up such a very large part of the THD, while still allowing beam tubes and pentodes to give much larger power than available before. The "invention" of Class AB as a hi- fidelity amp is what spurred part of a Olsen's work on perception; before it wasn't known that odd harmonics are proportionately much more disturbing than even harmonics. It seems to me that AB amps with largish parts of their output in Class A is a relatively modern trend, possibly related to ever less-sensitive speakers. One might also observe that's likely why it's called Class AB and not Class insert unique letter. There is in fact a class between Class A and Class AB with a unique description: "Limiting Class A1", which is set up so that the crossover happens when one valve just reaches current cutoff and the other simultaneously reaches zero bias. It makes for an amazingly smooth sound but it is a bitch to set up and keep tuned if you want to keep your circuits simple. I was therefore rather interested in what Patrick said elsewhere in this thread (in more general sense rather than specifically about LImitiing Class A1) about within 10 per cent of conduction angle being imperceptible... Andre Jute Visit Jute on Amps at http://members.lycos.co.uk/fiultra/ "wonderfully well written and reasoned information for the tube audio constructor" John Broskie TubeCAD & GlassWare "an unbelievably comprehensive web site containing vital gems of wisdom" Stuart Perry Hi-Fi News & Record Review |
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