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how good are class D amplifiers?
"Don Pearce" wrote in message
... On Tue, 22 May 2007 09:33:16 +0100, "Serge Auckland" wrote: Are there many distortion analysers any more that simply null the fundamental and display the sum of the rest? d -- Pearce Consulting http://www.pearce.uk.com Most if not all of the legacy distortion analysers will be of the nulling sort, and lab test gear has a very long life so I suspect (but don't know for sure) that a very high proportion of distortion analysers in regular use are still of that sort. Today's sales of test equipment are relatively very low. Studios and broadcasters rarely buy new audio test gear as they already have instruments for their remaining analogue stuff, and all this new digital stuff either works or it doesn't, and anyway, if it goes wrong it needs someone from the factory to come and see to it. When I worked for an audio test equipment manufacturer some 10-12 years ago, it was by then already clear that very little new audio test equipment was being sold. I think we made more money from the recalibration charges on the existing installed park than from selling new equipment. OK. Kind of surprising, though, as just about everybody now possesses a distortion meter at least as good as a nulling type. I'm talking about a PC sound card, of course. Just needs suitable software. d -- Pearce Consulting http://www.pearce.uk.com I have two conventional nulling THD meters and of course a sound card and software. However, for THD measurements I rarely use the sound card as it is too difficult to use . Firstly you need an attenuator to reduce the incoming level, as few soundcards take more than a couple of volts of input before clipping themselves, idealy, you need a millivoltmeter in parallel with the sound card input to make sure the level stays when it should. Then, with software, I never really know what it's measuring and finally, unless you have a suitable sound card and sample at 192kHz, you can't measure over the 100kHz bandwidth that most THD meters manage. I use the software test set for analysing WAV files. For example, it's easier for me to take my laptop to the hi-fi than test gear, so if I'm making any measurements to my room or system, I will record the DUT as a WAV and analyse it later. For that the software's great but for lab work, I prefer dedicated instruments. S. -- http://audiopages.googlepages.com |
how good are class D amplifiers?
"Jim Lesurf" wrote in message ... In article , Keith G wrote: "Trevor Wilson" wrote **Because that is a fact. The ideal amplifier has no 'sound' of it's own. No amplifier is ideal. Therefore no amplifier has no 'sound' of its own then? **Nope. That's not what I said. It's what it looks like to me - your words (as above): "The ideal amplifier has no 'sound' of it's own. No amplifier is ideal." - what conclusion could be possibly drawn from that statement other than all amplifiers are not ideal and therefore have a 'sound'...?? I can suggest at least two "conclusions" which fit with what Trevor said. 1) That "ideal" is defined in this context to mean what he wrote. i.e. that an ideal amp would/will have no "sound". That's what he said. 2) That this isn't a matter of a false dichtomy. i.e. *some* amps might have no "sound". Not a matter of all or none. That's not what he said. In the above respect I have my doubt about the way people are trying to use both terms, "ideal" and "sound". So far as I know there have been various controlled tests where no-one listening was able to distinguish one of the amps under comparison from another. Also tests where no-one was able to distinguish the amp followed by a resistive attenuator from a wire bypass. Thus I doubt it is the case that no amp is "ideal" in the terms Trevor used. The reason such tests have been rare in audio mags in recent years may be that the reviewers got fed up with tests whose results indicated that they could not find reliable evidence to support their belief that they could hear differences, plus that doing such a test requires more time, care, and understanding than they could be bothered to apply. :-) A variation on the 'if it sounds good, measure it until you know it *isn't* good'...?? Also, the "sound" produced by the amp is as a result of feeding it with an imput signal and playing its output via a speaker. This definition means it is a result of how it may (or may not) alter the signal in a way that has an audible effect. That means the "sound" depends on both the signal used and the loudspeakers, and is based upon any signal alterations made by the amp in that use. Of course, the amp may be adding audible noise/hum and making mechanical buzzing noises which might be a "sound" of its own. Otherwise any "sound" will be based on it altering the signal so that the output isn't simply a scaled version of the input, and the changes are large enough to be audible. Or not, according to the individual - which is why/how some people can claim one amp is 'better' than another... Personally, what I've found interesting over the years is just how large the changes in signal waveforms can be in some situations without people actually noticing, yet people say they can hear things when tests relying on sound alone fail to support their claim. I place little value on short duration listening tests - to much hidden voodoo at work - my method (and the one I would recommend) is to spend a period of many weeks or some months comparing two similar pieces of kit. A clear choice will evolve without having to make a decision, I usually find... |
how good are class D amplifiers?
"Dave Plowman (News)" wrote in message ... In article , Keith G wrote: Might that be that 'remote controls' for LP decks tend to be like hen's teeth? Here's mine: http://www.apah69.dsl.pipex.com/show/AiwaRemote.JPG Fits this deck (far right, under the name badge on the fascia panel): http://www.apah69.dsl.pipex.com/show/AiwaDeck.JPG If there was (or had been) a market for them, they would have been more widely available... And this allows you to instantly change tracks as does a CD one? Sure, as well as navigate backwards and forwards within the tracks like a CD player - very handy if you are listening to, say, the '1812' whilst straddled by the au pair and you want to synchronise the *big finish*.... (Usually 'FFwd' in my case.... :-) |
how good are class D amplifiers?
"Serge Auckland" wrote in
message Indeed, and in my previous post of the criteria, it was stated that THD should be measured at all frequencies 20-20k and refers to all powers and all loads for which the amplifier was designed. Measuring THD above 10 KHz can be an exercise in futility, as many upper harmonics will be lost due to the bandpass of the UUT. It's not uncommon for power amps to be - 3dB at 50 KHz, for example. Better to use twin-tone measurement techniques. |
how good are class D amplifiers?
"Serge Auckland" wrote in
message I rarely use the sound card as it is too difficult to use . Firstly you need an attenuator to reduce the incoming level, as few soundcards take more than a couple of volts of input before clipping themselves, idealy A 5K 2 watt high quality potentiometer suffices. you need a millivoltmeter in parallel with the sound card input to make sure the level stays when it should. You mean a voltmeter across the UUT output. We often used those with the old nulling-type analyzers for one reason or the other. Then, with software, I never really know what it's measuring That's your fault - a good experimentalist should be able to determine that with a few real world measurements. On a bad day, analyze some signals generated for the purpose. Generating complex tones is very easy these days. unless you have a suitable sound card and sample at 192kHz, you can't measure over the 100kHz bandwidth that most THD meters manage. Virtually every sound card that I'd consider to be an alternative to test equipment samples that high. I use the software test set for analysing WAV files. For example, it's easier for me to take my laptop to the hi-fi than test gear, so if I'm making any measurements to my room or system, I will record the DUT as a WAV and analyse it later. Agreed - it is easy to capture data in the field, and analyze it in detail later on. |
how good are class D amplifiers?
"Rob" wrote in message
I simply don't get this. I've been using 5 SS amps of late (Quad 405, Rose power amp, Cambridge AV, Behringer A500, and that within a Pure mini system), as well as others on and off over the years, and I feel each has 'a sound of its own'. Good choice of words - "I feel". IOW what your emotions tell you, not necessarily what well-reasoned testing would tell you. |
how good are class D amplifiers?
"Arny Krueger" wrote in message ... "Serge Auckland" wrote in message I rarely use the sound card as it is too difficult to use . Firstly you need an attenuator to reduce the incoming level, as few soundcards take more than a couple of volts of input before clipping themselves, idealy A 5K 2 watt high quality potentiometer suffices. you need a millivoltmeter in parallel with the sound card input to make sure the level stays when it should. You mean a voltmeter across the UUT output. We often used those with the old nulling-type analyzers for one reason or the other. No, I mean across the sound card input, so I know what's going into it to avoid it clipping. In practice, that may also be across the DUT (or UUT if you prefer) output, but what's important to me when using a soundcard is that I don't clip its input. Then, with software, I never really know what it's measuring That's your fault - a good experimentalist should be able to determine that with a few real world measurements. On a bad day, analyze some signals generated for the purpose. Generating complex tones is very easy these days. Agreed, if I could be bothered, but as I have two null-type meters available, I really can't be fagged. unless you have a suitable sound card and sample at 192kHz, you can't measure over the 100kHz bandwidth that most THD meters manage. Virtually every sound card that I'd consider to be an alternative to test equipment samples that high. My current laptop's internal sound card offers 192k sampling, and it actually works! However, I prefer to use my Digigram card for anything serious as its noise performance is much better, but it samples only up to 48k. I use the software test set for analysing WAV files. For example, it's easier for me to take my laptop to the hi-fi than test gear, so if I'm making any measurements to my room or system, I will record the DUT as a WAV and analyse it later. Agreed - it is easy to capture data in the field, and analyze it in detail later on. If I were still a practicing engineer I would probably get with modernity and have PC based test tools, but as now my engineering is for personal pleasure only, I have a set of old-fashioned instruments that are good enough for the purpose of hobbying. If noise/distortion etc is below what I can measure, I go and worry about other things. S. -- http://audiopages.googlepages.com |
how good are class D amplifiers?
In article , Serge Auckland
wrote: "Jim Lesurf" wrote in message ... I'd also tend to use a THD+Noise value as otherwise effects like PSU intermod might be missed as their components don't crop up at harmonics of the test frequency in most cases. I've seen amps where the THD value was low, but where there was much more LF garbage due to Indeed, and in my previous post of the criteria, it was stated that THD should be measured at all frequencies 20-20k and refers to all powers and all loads for which the amplifier was designed. In practice, the measurements are actually THD+N as this is what distortion meters actually measure. Of course the use of a harmonic analyser for distortion measurement won't pick up the +N component, but as a practicing engineer, I found the use of such an instrument to be tedious in the extreme, and unnecessary when an overall THD+N figure was so easily achieved. Well, I've used both 'traditional' THD+N kit that works by nulling or filtering the test sinusoid, and a specan/generator that autofinds the harmonics and works out THD. The second didn't seem at all 'tedious' to use as it automated the process. It was also faster than the old distortion kits I used to use that took some seconds to null down for low distortion. I suspect that people use either form of kit, whichever is to hand. The difficulty with this being what we discuss above. Slainte, Jim -- Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html |
how good are class D amplifiers?
In article , Don Pearce
wrote: On Tue, 22 May 2007 09:19:09 +0100, "Serge Auckland" wrote: Indeed, and in my previous post of the criteria, it was stated that THD should be measured at all frequencies 20-20k and refers to all powers and all loads for which the amplifier was designed. In practice, the measurements are actually THD+N as this is what distortion meters actually measure. Of course the use of a harmonic analyser for distortion measurement won't pick up the +N component, but as a practicing engineer, I found the use of such an instrument to be tedious in the extreme, and unnecessary when an overall THD+N figure was so easily achieved. S. The problem becomes more complex when you use an FFT analyser, as I suspect most are these days. You then need to consider the number of points in the FFT, and the way they display noise. Discrete signals are easy - whatever you do with the FFT, they look the same size, but the "+noise" bit will change with the number of points. Erm. It should be the total noise in the audio range. This means that however many bins it was divided into becomes irrelevant as they are then summed. Although I'd agree that a small fraction of the noise will be in the input signal bin and would be 'lost'. In recent years I've tended to use a Stanford Instruments unit that combines a test waveform generator and an FFT specan, and 'automates' the process as you wish. The trick, of course, is to know what process to specifiy and to understand how to interpret the results - especially when the spectrum on the screen isn't simple. :-) The noise floor problem is more significant when reviews simply display the floor value in terms of the per-bin level without having any clue what resolution bandwidth they are using. In those cases your comment does indeed apply, and makes the floors shown in some magazines worthless. Having tried discuss this with one or two people I fear that this issue whooshes over the head of some of them. Although there are others who clearly understand it, but don't use such meaningless plots. Are there many distortion analysers any more that simply null the fundamental and display the sum of the rest? Dunno. The last one I used a lot was the Sound Technology 1000A about two decades ago. This was very nice, but took a few seconds to settle into a null, etc, whenever you altered anything. Worked down to about 0.002% though, IIRC. I think that part of the delay was for the light bulb in the oscillator to settle when you changed frequency. ;- Slainte, Jim -- Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html |
how good are class D amplifiers?
"Arny Krueger" wrote in message . .. "Rob" wrote in message I simply don't get this. I've been using 5 SS amps of late (Quad 405, Rose power amp, Cambridge AV, Behringer A500, and that within a Pure mini system), as well as others on and off over the years, and I feel each has 'a sound of its own'. Good choice of words - "I feel". IOW what your emotions tell you, not necessarily what well-reasoned testing would tell you. Yep, why waste time *listening* to a bit of kit when you could just stick a meter on it....?? |
how good are class D amplifiers?
"Keith G" wrote in message ... "Arny Krueger" wrote in message . .. "Rob" wrote in message I simply don't get this. I've been using 5 SS amps of late (Quad 405, Rose power amp, Cambridge AV, Behringer A500, and that within a Pure mini system), as well as others on and off over the years, and I feel each has 'a sound of its own'. Good choice of words - "I feel". IOW what your emotions tell you, not necessarily what well-reasoned testing would tell you. Yep, why waste time *listening* to a bit of kit when you could just stick a meter on it....?? Works for me! If I want to know what something is doing, I'll take measurements over ears any day. S. -- http://audiopages.googlepages.com |
how good are class D amplifiers?
In article ,
Keith G wrote: Yep, why waste time *listening* to a bit of kit when you could just stick a meter on it....?? Indeed. A doctor with a stethoscope beats a MRI scan every time. -- *Suicidal twin kills sister by mistake. Dave Plowman London SW To e-mail, change noise into sound. |
how good are class D amplifiers?
Dave Plowman (News) wrote:
In article , Keith G wrote: Yep, why waste time *listening* to a bit of kit when you could just stick a meter on it....?? Indeed. A doctor with a stethoscope beats a MRI scan every time. Why look at (with your eyes?!) a picture when you can digitally analyse it? Why go for a walk when there's perfectly good GIS profile of your route? Why listen to music when ... :-) |
how good are class D amplifiers?
"Serge Auckland" wrote in
message "Arny Krueger" wrote in message ... "Serge Auckland" wrote in message I rarely use the sound card as it is too difficult to use . Firstly you need an attenuator to reduce the incoming level, as few soundcards take more than a couple of volts of input before clipping themselves, idealy A 5K 2 watt high quality potentiometer suffices. you need a millivoltmeter in parallel with the sound card input to make sure the level stays when it should. You mean a voltmeter across the UUT output. We often used those with the old nulling-type analyzers for one reason or the other. No, I mean across the sound card input, so I know what's going into it to avoid it clipping. If you follow my software recommendations, that is redundant. In practice, that may also be across the DUT (or UUT if you prefer) output, but what's important to me when using a soundcard is that I don't clip its input. Unless you're measuring some really dirty crap, audio interface overload sticks out like a sore thumb. Then, with software, I never really know what it's measuring That's your fault - a good experimentalist should be able to determine that with a few real world measurements. On a bad day, analyze some signals generated for the purpose. Generating complex tones is very easy these days. Agreed, if I could be bothered, but as I have two null-type meters available, I really can't be fagged. I have just one null-type meter, but I can't be bothered with using it. unless you have a suitable sound card and sample at 192kHz, you can't measure over the 100kHz bandwidth that most THD meters manage. Virtually every sound card that I'd consider to be an alternative to test equipment samples that high. My current laptop's internal sound card offers 192k sampling, and it actually works! However, I prefer to use my Digigram card for anything serious as its noise performance is much better, but it samples only up to 48k. Lots of other options. I use the software test set for analysing WAV files. For example, it's easier for me to take my laptop to the hi-fi than test gear, so if I'm making any measurements to my room or system, I will record the DUT as a WAV and analyse it later. Agreed - it is easy to capture data in the field, and analyze it in detail later on. If I were still a practicing engineer I would probably get with modernity and have PC based test tools, but as now my engineering is for personal pleasure only, I have a set of old-fashioned instruments that are good enough for the purpose of hobbying. If noise/distortion etc is below what I can measure, I go and worry about other things. A practical approach, in all liklihood. |
how good are class D amplifiers?
"Keith G" wrote in message
"Arny Krueger" wrote in message . .. "Rob" wrote in message I simply don't get this. I've been using 5 SS amps of late (Quad 405, Rose power amp, Cambridge AV, Behringer A500, and that within a Pure mini system), as well as others on and off over the years, and I feel each has 'a sound of its own'. Good choice of words - "I feel". IOW what your emotions tell you, not necessarily what well-reasoned testing would tell you. Yep, why waste time *listening* to a bit of kit when you could just stick a meter on it....?? Agreed that sighted listening is pretty worthless, if the equipment is good enough to be interesting. |
how good are class D amplifiers?
"Rob" wrote in message
Dave Plowman (News) wrote: In article , Keith G wrote: Yep, why waste time *listening* to a bit of kit when you could just stick a meter on it....?? Indeed. A doctor with a stethoscope beats a MRI scan every time. Why look at (with your eyes?!) a picture when you can digitally analyse it? If you had a clue about audio measurements, you'd know why your comparison is a bad joke. |
how good are class D amplifiers?
On Tue, 22 May 2007 19:11:40 +0100, Rob
wrote: Dave Plowman (News) wrote: In article , Keith G wrote: Yep, why waste time *listening* to a bit of kit when you could just stick a meter on it....?? Indeed. A doctor with a stethoscope beats a MRI scan every time. Why look at (with your eyes?!) a picture when you can digitally analyse it? Why go for a walk when there's perfectly good GIS profile of your route? Why listen to music when ... :-) But the measurements aren't a substitute for listening - they are designed to make sure your equipment is not going to mar your pleasure. A bit like making sure the glass on the front of your picture is nice and clear... Of course there are those who like cloudy glass with a coloured tint, but not those who want to see the whole of the picture. d -- Pearce Consulting http://www.pearce.uk.com |
how good are class D amplifiers?
Don Pearce wrote:
On Tue, 22 May 2007 19:11:40 +0100, Rob wrote: Dave Plowman (News) wrote: In article , Keith G wrote: Yep, why waste time *listening* to a bit of kit when you could just stick a meter on it....?? Indeed. A doctor with a stethoscope beats a MRI scan every time. Why look at (with your eyes?!) a picture when you can digitally analyse it? Why go for a walk when there's perfectly good GIS profile of your route? Why listen to music when ... :-) But the measurements aren't a substitute for listening - they are designed to make sure your equipment is not going to mar your pleasure. It strikes me that measurement fixation *does* affect listening. For some, a measured anomaly would take away some of the listening pleasure even if it was inaudible. A bit like making sure the glass on the front of your picture is nice and clear... Of course there are those who like cloudy glass with a coloured tint, but not those who want to see the whole of the picture. d Some people like their glass 'distorted' so they can see the bigger picture. |
how good are class D amplifiers?
On Tue, 22 May 2007 20:45:32 +0100, Rob
wrote: Don Pearce wrote: On Tue, 22 May 2007 19:11:40 +0100, Rob wrote: Dave Plowman (News) wrote: In article , Keith G wrote: Yep, why waste time *listening* to a bit of kit when you could just stick a meter on it....?? Indeed. A doctor with a stethoscope beats a MRI scan every time. Why look at (with your eyes?!) a picture when you can digitally analyse it? Why go for a walk when there's perfectly good GIS profile of your route? Why listen to music when ... :-) But the measurements aren't a substitute for listening - they are designed to make sure your equipment is not going to mar your pleasure. It strikes me that measurement fixation *does* affect listening. For some, a measured anomaly would take away some of the listening pleasure even if it was inaudible. Would it take you that way? Not me, that is for sure. ANd by now I have a very good idea of what is audible and what is not. Add to that the fact that it is trivially easy these days to make equipment with errors many orders of magnitude below audibility, and the situation is really pretty relaxed. A bit like making sure the glass on the front of your picture is nice and clear... Of course there are those who like cloudy glass with a coloured tint, but not those who want to see the whole of the picture. d Some people like their glass 'distorted' so they can see the bigger picture. No, you never see the bigger picture through distorted glass. You always see less - no choice there, I'm afraid. And of course you have not the slightest chance of seeing the details. d -- Pearce Consulting http://www.pearce.uk.com |
how good are class D amplifiers?
Don Pearce wrote:
On Tue, 22 May 2007 20:45:32 +0100, Rob wrote: Don Pearce wrote: On Tue, 22 May 2007 19:11:40 +0100, Rob wrote: Dave Plowman (News) wrote: In article , Keith G wrote: Yep, why waste time *listening* to a bit of kit when you could just stick a meter on it....?? Indeed. A doctor with a stethoscope beats a MRI scan every time. Why look at (with your eyes?!) a picture when you can digitally analyse it? Why go for a walk when there's perfectly good GIS profile of your route? Why listen to music when ... :-) But the measurements aren't a substitute for listening - they are designed to make sure your equipment is not going to mar your pleasure. It strikes me that measurement fixation *does* affect listening. For some, a measured anomaly would take away some of the listening pleasure even if it was inaudible. Would it take you that way? Not me, that is for sure. ANd by now I have a very good idea of what is audible and what is not. Add to that the fact that it is trivially easy these days to make equipment with errors many orders of magnitude below audibility, and the situation is really pretty relaxed. Well, yes it has affected my listening pleasure for a time. Maybe I'm alone. A bit like making sure the glass on the front of your picture is nice and clear... Of course there are those who like cloudy glass with a coloured tint, but not those who want to see the whole of the picture. d Some people like their glass 'distorted' so they can see the bigger picture. No, you never see the bigger picture through distorted glass. You always see less - no choice there, I'm afraid. And of course you have not the slightest chance of seeing the details. Try telling my wing mirrors :-) |
how good are class D amplifiers?
On Tue, 22 May 2007 21:10:47 +0100, Rob
wrote: Don Pearce wrote: On Tue, 22 May 2007 20:45:32 +0100, Rob wrote: Don Pearce wrote: On Tue, 22 May 2007 19:11:40 +0100, Rob wrote: Dave Plowman (News) wrote: In article , Keith G wrote: Yep, why waste time *listening* to a bit of kit when you could just stick a meter on it....?? Indeed. A doctor with a stethoscope beats a MRI scan every time. Why look at (with your eyes?!) a picture when you can digitally analyse it? Why go for a walk when there's perfectly good GIS profile of your route? Why listen to music when ... :-) But the measurements aren't a substitute for listening - they are designed to make sure your equipment is not going to mar your pleasure. It strikes me that measurement fixation *does* affect listening. For some, a measured anomaly would take away some of the listening pleasure even if it was inaudible. Would it take you that way? Not me, that is for sure. ANd by now I have a very good idea of what is audible and what is not. Add to that the fact that it is trivially easy these days to make equipment with errors many orders of magnitude below audibility, and the situation is really pretty relaxed. Well, yes it has affected my listening pleasure for a time. Maybe I'm alone. The fact that audio design engineers have measured every aspect of your favourite amp, and slaved assiduously to make sure that it is as good as it can possibly be has adversely affected your listening pleasure? That actually sounds a little ungrateful to me. A bit like making sure the glass on the front of your picture is nice and clear... Of course there are those who like cloudy glass with a coloured tint, but not those who want to see the whole of the picture. d Some people like their glass 'distorted' so they can see the bigger picture. No, you never see the bigger picture through distorted glass. You always see less - no choice there, I'm afraid. And of course you have not the slightest chance of seeing the details. Try telling my wing mirrors :-) You have distorting wing mirrors? I don't count gain or attenuation, of course ;-) Objects seen in this mirror are fatter than they look, heh? d -- Pearce Consulting http://www.pearce.uk.com |
how good are class D amplifiers?
In article , Dave Plowman (News)
writes In article , tony sayer wrote: Not so easy these days given even a modest but decent sound system straight out of the box. Including yer DABble radio eh Dave;?... No one is forcing you to listen to DAB, and never will. If you don't like it for anything use one of the alternatives. You're obviously in the enviable position of having perfect reception off FM both at home and in the car - or more likely are so used to the distortion caused by multipath you don't notice it anymore. Loosen up M8 'twas only a ****take;) -- Tony Sayer |
Noblesse oblige.....
"Don Pearce" wrote But the measurements aren't a substitute for listening - they are designed to make sure your equipment is not going to mar your pleasure. A bit like making sure the glass on the front of your picture is nice and clear... Of course there are those who like cloudy glass with a coloured tint, but not those who want to see the whole of the picture. Why are my ears burning?? :-) OK. Lemme tell ya summat for nowt... A short while back I met 'Mr X' when I bought the first of two recent 'bikes and we got on to hifi (as you do). He is/was an avid 'enthusiast' and had 9 pieces (I'm sure he said) of Cyrus kit, Impulse 'Lali' (?) speakers and no vinyl - ie *blameless* to a fault (the perfect ukra paradigm)! As of now (a number of 'seshes' later) he has 300B SET monos, Lowther 'horns' and (as of yesterday) a Lenco GL75 turntable in natty steel plinth. Go figure.... (He still has his CD player, you'll be pleased/relieved to hear!) Go figure again... (And I have his colleague's TLS80s... ;-) |
how good are class D amplifiers?
"Don Pearce" wrote No, you never see the bigger picture through distorted glass. You always see less - no choice there, I'm afraid. Yes you do - it's called a wide-angle lens... And of course you have not the slightest chance of seeing the details. Yes you do - it's called a magnifying lens.... |
how good are class D amplifiers?
"Arny Krueger" wrote in message . .. "Keith G" wrote in message "Arny Krueger" wrote in message . .. "Rob" wrote in message I simply don't get this. I've been using 5 SS amps of late (Quad 405, Rose power amp, Cambridge AV, Behringer A500, and that within a Pure mini system), as well as others on and off over the years, and I feel each has 'a sound of its own'. Good choice of words - "I feel". IOW what your emotions tell you, not necessarily what well-reasoned testing would tell you. Yep, why waste time *listening* to a bit of kit when you could just stick a meter on it....?? Agreed that sighted listening is pretty worthless, if the equipment is good enough to be interesting. Anybody who sits staring at a bit of audio kit while it plays (typically the cartridge on a turntable, I find) needs a slap round the chops.... |
how good are class D amplifiers?
"tony sayer" wrote in message ... In article , Dave Plowman (News) writes In article , tony sayer wrote: Not so easy these days given even a modest but decent sound system straight out of the box. Including yer DABble radio eh Dave;?... No one is forcing you to listen to DAB, and never will. If you don't like it for anything use one of the alternatives. You're obviously in the enviable position of having perfect reception off FM both at home and in the car - or more likely are so used to the distortion caused by multipath you don't notice it anymore. Loosen up M8 'twas only a ****take;) Oi! Do you mind? That's *my* job.... |
how good are class D amplifiers?
"Serge Auckland" wrote in message ... "Keith G" wrote in message ... "Arny Krueger" wrote in message . .. "Rob" wrote in message I simply don't get this. I've been using 5 SS amps of late (Quad 405, Rose power amp, Cambridge AV, Behringer A500, and that within a Pure mini system), as well as others on and off over the years, and I feel each has 'a sound of its own'. Good choice of words - "I feel". IOW what your emotions tell you, not necessarily what well-reasoned testing would tell you. Yep, why waste time *listening* to a bit of kit when you could just stick a meter on it....?? Works for me! If I want to know what something is doing, I'll take measurements over ears any day. For a crash helmet, presumably? :-) |
Noblesse oblige.....
On Tue, 22 May 2007 23:43:20 +0100, "Keith G"
wrote: "Don Pearce" wrote But the measurements aren't a substitute for listening - they are designed to make sure your equipment is not going to mar your pleasure. A bit like making sure the glass on the front of your picture is nice and clear... Of course there are those who like cloudy glass with a coloured tint, but not those who want to see the whole of the picture. Why are my ears burning?? :-) OK. Lemme tell ya summat for nowt... A short while back I met 'Mr X' when I bought the first of two recent 'bikes and we got on to hifi (as you do). He is/was an avid 'enthusiast' and had 9 pieces (I'm sure he said) of Cyrus kit, Impulse 'Lali' (?) speakers and no vinyl - ie *blameless* to a fault (the perfect ukra paradigm)! As of now (a number of 'seshes' later) he has 300B SET monos, Lowther 'horns' and (as of yesterday) a Lenco GL75 turntable in natty steel plinth. Go figure.... (He still has his CD player, you'll be pleased/relieved to hear!) Go figure again... (And I have his colleague's TLS80s... ;-) This is all fine. We all love to go into the hall of mirrors at the fair, don't we? d -- Pearce Consulting http://www.pearce.uk.com |
how good are class D amplifiers?
Keith G wrote:
"tony sayer" wrote in message ... Loosen up M8 'twas only a ****take;) Oi! Do you mind? That's *my* job.... If you're going to start a demarcation dispute, brother Keith, a bit less of the Socratic irony please. That's my job. :-) -- Eiron. May contain traces of irony. |
how good are class D amplifiers?
On Wed, 23 May 2007 07:32:32 +0100, Eiron wrote:
Keith G wrote: "tony sayer" wrote in message ... Loosen up M8 'twas only a ****take;) Oi! Do you mind? That's *my* job.... If you're going to start a demarcation dispute, brother Keith, a bit less of the Socratic irony please. That's my job. :-) In that case, you'd better leave the sarcasm to me, thank you very much! d -- Pearce Consulting http://www.pearce.uk.com |
Noblesse oblige.....
"Don Pearce" wrote in message ... On Tue, 22 May 2007 23:43:20 +0100, "Keith G" wrote: OK. Lemme tell ya summat for nowt... A short while back I met 'Mr X' when I bought the first of two recent 'bikes and we got on to hifi (as you do). He is/was an avid 'enthusiast' and had 9 pieces (I'm sure he said) of Cyrus kit, Impulse 'Lali' (?) speakers and no vinyl - ie *blameless* to a fault (the perfect ukra paradigm)! As of now (a number of 'seshes' later) he has 300B SET monos, Lowther 'horns' and (as of yesterday) a Lenco GL75 turntable in natty steel plinth. Go figure.... (He still has his CD player, you'll be pleased/relieved to hear!) Go figure again... (And I have his colleague's TLS80s... ;-) And probably the neat little valve preamp I came away with last night..... This is all fine. We all love to go into the hall of mirrors at the fair, don't we? He hasn't *gone into* the hall of mirrors, he has *moved into* it - the Cyrus gear has all been sold, I gather. You need to know I'm not *selling* anything, Don Old (other than when I *am* selling summat) - when people come here for a listen and start making better or worse noises, I shrug my shoulders. I have a ton of *everything* and I like it all - right now is DAB on SS amp, later (much later if this sun holds) will probably a bit of vinyl on triodes/horns at some point. (There's one or two here could do with a trip to the hall of mirrors when it comes to throwing the 'bigot' word around...) |
how good are class D amplifiers?
In article , Rob
wrote: Don Pearce wrote: On Tue, 22 May 2007 19:11:40 +0100, Rob wrote: But the measurements aren't a substitute for listening - they are designed to make sure your equipment is not going to mar your pleasure. It strikes me that measurement fixation *does* affect listening. However not all interest in using measurements and understanding their meanings would be a 'fixation'. For some, a measured anomaly would take away some of the listening pleasure even if it was inaudible. So far as I know, there is no law requiring you to read any of the specs or measurements for any equipment you buy and use. :-) However if you actually *understand* the measurements you can easily make up your mind if any 'anomaly' matters. Indeed, reading and understanding 'measurements' might save you from wasting time money buying a lemon. A bit like making sure the glass on the front of your picture is nice and clear... Of course there are those who like cloudy glass with a coloured tint, but not those who want to see the whole of the picture. d Some people like their glass 'distorted' so they can see the bigger picture. Indeed. However it can be useful for them and others to know the cause and effect involved. This would then give them info useful when they and others decide what other 'glass' to choose for specific purposes, or to get results they would feel are a further improvement. Interestingly, your analogy also implicitly assumes the 'people' know that the result *is* being 'distorted' by the 'glass', rather than assuming that what they see is what they'd get if the glass were absent and their view was direct. The snag in audio is that many people may have no such awareness, and indeed, no chance to do the equivalent of seeing the view directly. Another snag is that in the case of audio there may be many thousands of different 'pictures' to 'view' and you might like some 'distorted' by a specific 'glass', but other 'distorted' in other ways. So perhaps this is simply another attempt at analogy that falls apart once you try to use it at more that a trivial level. ;- More generally... The problem with wilful ignorance is that it gives you no guide if you ever need to change anything. Similarly, it is no help to anyone else who is interested in the results you got. Nor does it tell anyone if what is claimed is for the reasons claimed, or is even real rather than delusional. I suppose I am old-fashioned. I prefer education and understanding to ignorance, and I prefer views based on reliable evidence. Indeed, I seem to get a lot of enjoyment and satisfaction out of learning, understanding, etc. My experience thus far is that this has helped me to design/choose/use equipment to allow me to enjoy recorded and broadcast music. I have also repeatedly found that ideas presented in claims by people have no foundations, so would probably have wasted my time and impeded my being able to get to where I have in terms of enjoying the results if I hadn't had the old-fashioned approach of using measurements, understanding, etc, to try and find my way though the claims. In my experience this has complimented listening very well. So, no, I'm afraid I am not personally a great fan of wilful ignorance as a policy of choice. Slainte, Jim -- Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html |
how good are class D amplifiers?
On Tue, 22 May 2007 16:12:32 +0100, Jim Lesurf
wrote: In article , Don Pearce wrote: On Tue, 22 May 2007 09:19:09 +0100, "Serge Auckland" wrote: Indeed, and in my previous post of the criteria, it was stated that THD should be measured at all frequencies 20-20k and refers to all powers and all loads for which the amplifier was designed. In practice, the measurements are actually THD+N as this is what distortion meters actually measure. Of course the use of a harmonic analyser for distortion measurement won't pick up the +N component, but as a practicing engineer, I found the use of such an instrument to be tedious in the extreme, and unnecessary when an overall THD+N figure was so easily achieved. S. The problem becomes more complex when you use an FFT analyser, as I suspect most are these days. You then need to consider the number of points in the FFT, and the way they display noise. Discrete signals are easy - whatever you do with the FFT, they look the same size, but the "+noise" bit will change with the number of points. Erm. It should be the total noise in the audio range. This means that however many bins it was divided into becomes irrelevant as they are then summed. Although I'd agree that a small fraction of the noise will be in the input signal bin and would be 'lost'. In recent years I've tended to use a Stanford Instruments unit that combines a test waveform generator and an FFT specan, and 'automates' the process as you wish. The trick, of course, is to know what process to specifiy and to understand how to interpret the results - especially when the spectrum on the screen isn't simple. :-) The noise floor problem is more significant when reviews simply display the floor value in terms of the per-bin level without having any clue what resolution bandwidth they are using. In those cases your comment does indeed apply, and makes the floors shown in some magazines worthless. Having tried discuss this with one or two people I fear that this issue whooshes over the head of some of them. Although there are others who clearly understand it, but don't use such meaningless plots. Exactly - although the maths is very easy - just add 10 log (audio bandwidth / (bin bandwidth * windowing ratio)) to the noise level in dB. But as you say, this appears to be beyond most people. The problem is that you must do this to the noise, but not to the discrete signals, and it can get tricky sometimes separating the one from the other. Are there many distortion analysers any more that simply null the fundamental and display the sum of the rest? Dunno. The last one I used a lot was the Sound Technology 1000A about two decades ago. This was very nice, but took a few seconds to settle into a null, etc, whenever you altered anything. Worked down to about 0.002% though, IIRC. I think that part of the delay was for the light bulb in the oscillator to settle when you changed frequency. ;- Slainte, Jim I still have a couple of those tiny bead thermistors in vacuum tubes that are really good at stabilizing Wien Bridge oscillators. Better than light bulbs, I think. d -- Pearce Consulting http://www.pearce.uk.com |
how good are class D amplifiers?
On Tue, 22 May 2007 16:03:55 +0100, Jim Lesurf
wrote: In article , Serge Auckland wrote: "Jim Lesurf" wrote in message ... I'd also tend to use a THD+Noise value as otherwise effects like PSU intermod might be missed as their components don't crop up at harmonics of the test frequency in most cases. I've seen amps where the THD value was low, but where there was much more LF garbage due to Indeed, and in my previous post of the criteria, it was stated that THD should be measured at all frequencies 20-20k and refers to all powers and all loads for which the amplifier was designed. In practice, the measurements are actually THD+N as this is what distortion meters actually measure. Of course the use of a harmonic analyser for distortion measurement won't pick up the +N component, but as a practicing engineer, I found the use of such an instrument to be tedious in the extreme, and unnecessary when an overall THD+N figure was so easily achieved. Well, I've used both 'traditional' THD+N kit that works by nulling or filtering the test sinusoid, and a specan/generator that autofinds the harmonics and works out THD. The second didn't seem at all 'tedious' to use as it automated the process. It was also faster than the old distortion kits I used to use that took some seconds to null down for low distortion. I suspect that people use either form of kit, whichever is to hand. The difficulty with this being what we discuss above. Slainte, Jim There is a distinct advantage to the second, in that it gives you information about the nature of the harmonics. If you are making this measurement as part of a development process, that can be invaluable. d -- Pearce Consulting http://www.pearce.uk.com |
Noblesse oblige.....
On Wed, 23 May 2007 09:05:56 +0100, "Keith G"
wrote: "Don Pearce" wrote in message ... On Tue, 22 May 2007 23:43:20 +0100, "Keith G" wrote: OK. Lemme tell ya summat for nowt... A short while back I met 'Mr X' when I bought the first of two recent 'bikes and we got on to hifi (as you do). He is/was an avid 'enthusiast' and had 9 pieces (I'm sure he said) of Cyrus kit, Impulse 'Lali' (?) speakers and no vinyl - ie *blameless* to a fault (the perfect ukra paradigm)! As of now (a number of 'seshes' later) he has 300B SET monos, Lowther 'horns' and (as of yesterday) a Lenco GL75 turntable in natty steel plinth. Go figure.... (He still has his CD player, you'll be pleased/relieved to hear!) Go figure again... (And I have his colleague's TLS80s... ;-) And probably the neat little valve preamp I came away with last night..... This is all fine. We all love to go into the hall of mirrors at the fair, don't we? He hasn't *gone into* the hall of mirrors, he has *moved into* it - the Cyrus gear has all been sold, I gather. I wonder - will he stay there, though? You need to know I'm not *selling* anything, Don Old (other than when I *am* selling summat) - when people come here for a listen and start making better or worse noises, I shrug my shoulders. I have a ton of *everything* and I like it all - right now is DAB on SS amp, later (much later if this sun holds) will probably a bit of vinyl on triodes/horns at some point. I've given up listening to DAB at home - it is just too unpleasant. When I want to listen to the wireless, I use Freeview (except when I am sat here at my PC, in which case it is an AM/FM clock radio I got a million years ago with my Esso Tiger tokens). (There's one or two here could do with a trip to the hall of mirrors when it comes to throwing the 'bigot' word around...) Life is far too short to get wound up about all this stuff, really. d -- Pearce Consulting http://www.pearce.uk.com |
Noblesse oblige.....
"Don Pearce" wrote This is all fine. We all love to go into the hall of mirrors at the fair, don't we? He hasn't *gone into* the hall of mirrors, he has *moved into* it - the Cyrus gear has all been sold, I gather. I wonder - will he stay there, though? Dunno, what's scary is how he's ditched everything he had and made the complete 'leap of faith'!! Myself, I operate at least a 'one on and one in the wash' MO and have 7 or 8 different stereo amps here, just for starters.... You need to know I'm not *selling* anything, Don Old (other than when I *am* selling summat) - when people come here for a listen and start making better or worse noises, I shrug my shoulders. I have a ton of *everything* and I like it all - right now is DAB on SS amp, later (much later if this sun holds) will probably a bit of vinyl on triodes/horns at some point. I've given up listening to DAB at home - it is just too unpleasant. Whilst FM on the TLS80s can be just a bit too much of everything here.... goes to check Nope, it's fine and I've left it on! Must be the weather! When I want to listen to the wireless, I use Freeview (except when I am sat here at my PC, in which case it is an AM/FM clock radio I got a million years ago with my Esso Tiger tokens). My most-used bit of 'audio kit' is a wooden-cased Bush 'old style' radio which I must have had for 20 years (significant birthday present) - it gets used every single day at some point! (There's one or two here could do with a trip to the hall of mirrors when it comes to throwing the 'bigot' word around...) Life is far too short to get wound up about all this stuff, really. I think so, but you've got to counter their hot little faces and their silly little 'attacks' with summat, ain'tcha? ;-) (It's only fekkin' *hifi* at the end of the day!!) |
how good are class D amplifiers?
"Jim Lesurf" wrote in message ... In article , Serge Auckland wrote: "Jim Lesurf" wrote in message ... I'd also tend to use a THD+Noise value as otherwise effects like PSU intermod might be missed as their components don't crop up at harmonics of the test frequency in most cases. I've seen amps where the THD value was low, but where there was much more LF garbage due to Indeed, and in my previous post of the criteria, it was stated that THD should be measured at all frequencies 20-20k and refers to all powers and all loads for which the amplifier was designed. In practice, the measurements are actually THD+N as this is what distortion meters actually measure. Of course the use of a harmonic analyser for distortion measurement won't pick up the +N component, but as a practicing engineer, I found the use of such an instrument to be tedious in the extreme, and unnecessary when an overall THD+N figure was so easily achieved. Well, I've used both 'traditional' THD+N kit that works by nulling or filtering the test sinusoid, and a specan/generator that autofinds the harmonics and works out THD. The second didn't seem at all 'tedious' to use as it automated the process. It was also faster than the old distortion kits I used to use that took some seconds to null down for low distortion. When I was designing audio equipment, I never had the luxury of an autofinder, the one I used was a Marconi Instruments meter which in effects was a highly selective filter and meter, and to use it, one found each harmnic individually, measured its level, then worked out the THD by algebra. As I said, tedious in the extreme. I much preferred the Radford LDO/DMS combination, or the Ferrograph for a quick and dirty measurement. More recently, I had the use of a Lindos LA100 test set, which measured THD automatically, and printed out the results or sent a file to a PC. Sadly, I couldn't keep it when I left the company. S -- http://audiopages.googlepages.com |
Noblesse oblige.....
In article ,
Don Pearce wrote: I've given up listening to DAB at home - it is just too unpleasant. When I want to listen to the wireless, I use Freeview (except when I am sat here at my PC, in which case it is an AM/FM clock radio I got a million years ago with my Esso Tiger tokens). Are you really saying that sounds better than DAB through a decent system? ;-) -- *Would a fly without wings be called a walk? Dave Plowman London SW To e-mail, change noise into sound. |
Noblesse oblige.....
On Wed, 23 May 2007 11:00:41 +0100, "Dave Plowman (News)"
wrote: In article , Don Pearce wrote: I've given up listening to DAB at home - it is just too unpleasant. When I want to listen to the wireless, I use Freeview (except when I am sat here at my PC, in which case it is an AM/FM clock radio I got a million years ago with my Esso Tiger tokens). Are you really saying that sounds better than DAB through a decent system? ;-) No - it sounds bloody awful - but in a way I can accept. DAB, through a decent system is what I would use to settle down to serious listening. For that it is totally unacceptable. d -- Pearce Consulting http://www.pearce.uk.com |
how good are class D amplifiers?
In article , Don Pearce
wrote: On Tue, 22 May 2007 16:03:55 +0100, Jim Lesurf wrote: Well, I've used both 'traditional' THD+N kit that works by nulling or filtering the test sinusoid, and a specan/generator that autofinds the harmonics and works out THD. The second didn't seem at all 'tedious' to use as it automated the process. It was also faster than the old distortion kits I used to use that took some seconds to null down for low distortion. There is a distinct advantage to the second, in that it gives you information about the nature of the harmonics. If you are making this measurement as part of a development process, that can be invaluable. When using the ST1000A I used to find it useful to view the result of the nulling on a scope. i.e. the waveform with the test sinusoid removed. This gave similar info provided you could 'interpret' the results. For example, very useful when adjusting the bias of an AB output as you could see any crossover error appear or vanish as you twiddled the bias. This has an advantage over power/frequency plots of the harmonics as it shows the effects of the relative phases as well. If I still had an ST1000A I'd probably be using it, but I lost access to it 20+ years ago... FWIW A month or two ago I wrote a simple example program that does this for a computing magazine. Found it quite interesting to view the nulled patterns from an old Shure cart playing a test LP. Slainte, Jim -- Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html |
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