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Troubleshooting: amplifier Musical Fidelity A1
Still many thanks for your help.
About the A1, what can I say? When I purchased the A1 I was 19 years old, and it seems to me to buy a "Cadillac" (also for the efforts to save the money!). It was really a pleasure to listen to it, with Celestion 5 speakers. Time goes by... I come to the feeling the A1 is a myth: * I thought it is 20 Watt class A, now I read it is only 2 Watt class A... It heats like a true class A to tweak the listeners ? * The volume pot failure is a design failure. * Some components (example the caps) are not well suited for the high temperature inside. * Users report different failures. * Musical Fidelity feedback is null... * Do you see http://www.musicalfidelity.com/merchandise.html ? Watches... pens... ridicolous! The "keep in touch" page: nothing to send a question, only their way to cater information from the user. Now I want to build a Gainclone. If it will sound better than A1 I understand the business: marketing and psichological stuff. I already think it for hi-end, but facing this also for the A1 is sad :-( Going to hi-fi and hi-end, you pay - sometimes, the handcraft manufacturing - the high costs of manufacturing low quantities - the brand - some excellent materials, but they don't improve sound quality (carved wood, gold everywhere, shark oil for cdrom, cables more expensive than Nasa Shuttle ones, abuse of special and expensive electronics parts to obfuscate customers minds - perhaps the design is weak, and so on...) Here it is my Murhpy law about hi-fi: price quality 10 10 % cheap 20 20 % midi 30 30 % 40 40 % mini 50 45 % hi-fi 60 48 % hi-fi 100 50 % hi-end 1000 55 % 10000 60 % madness! you never reach the perfection, it is all marketing hyphens. Better for your wallet, more amusing and satisfying is do some DIY project! ciao, Massimo ITALY |
Troubleshooting: amplifier Musical Fidelity A1
On Mon, 15 Dec 2003 17:33:17 +0100, Sala Massimo wrote:
Still many thanks for your help. About the A1, what can I say? When I purchased the A1 I was 19 years old, and it seems to me to buy a "Cadillac" (also for the efforts to save the money!). It was really a pleasure to listen to it, with Celestion 5 speakers. Time goes by... I come to the feeling the A1 is a myth: * I thought it is 20 Watt class A, now I read it is only 2 Watt class A... It heats like a true class A to tweak the listeners ? * The volume pot failure is a design failure. * Some components (example the caps) are not well suited for the high temperature inside. So? You've obviously had a lot of enjoyment from the A1. Forget the specs for a minute; do you still enjoy the sound that it makes? If so, why bother whether it is class A up to full power? It's all just numbers - it's your ears that have to be satisfied at the end of the day! If you are dissatisfied with the sound, why not build something like the Zen? You can have true class A then. You could even use a class A mosfet if you fancy trying that. If you *really* hate the A1 you could build a really nice Zen in the A1's case - it has a lovely heatsink just waiting ... or you could give it to me... :-) -- Mick http://www.nascom.info for Nascom & Gemini information Also at http://www.mixtel.co.uk where the collection started. Currently deserting M$ for linux... :-) |
Troubleshooting: amplifier Musical Fidelity A1
On Mon, 15 Dec 2003 17:33:17 +0100, Sala Massimo wrote:
Still many thanks for your help. About the A1, what can I say? When I purchased the A1 I was 19 years old, and it seems to me to buy a "Cadillac" (also for the efforts to save the money!). It was really a pleasure to listen to it, with Celestion 5 speakers. Time goes by... I come to the feeling the A1 is a myth: * I thought it is 20 Watt class A, now I read it is only 2 Watt class A... It heats like a true class A to tweak the listeners ? * The volume pot failure is a design failure. * Some components (example the caps) are not well suited for the high temperature inside. So? You've obviously had a lot of enjoyment from the A1. Forget the specs for a minute; do you still enjoy the sound that it makes? If so, why bother whether it is class A up to full power? It's all just numbers - it's your ears that have to be satisfied at the end of the day! If you are dissatisfied with the sound, why not build something like the Zen? You can have true class A then. You could even use a class A mosfet if you fancy trying that. If you *really* hate the A1 you could build a really nice Zen in the A1's case - it has a lovely heatsink just waiting ... or you could give it to me... :-) -- Mick http://www.nascom.info for Nascom & Gemini information Also at http://www.mixtel.co.uk where the collection started. Currently deserting M$ for linux... :-) |
Troubleshooting: amplifier Musical Fidelity A1
In article , Sala Massimo
wrote: Still many thanks for your help. About the A1, what can I say? When I purchased the A1 I was 19 years old, and it seems to me to buy a "Cadillac" (also for the efforts to save the money!). It was really a pleasure to listen to it, with Celestion 5 speakers. Time goes by... I come to the feeling the A1 is a myth: * I thought it is 20 Watt class A, now I read it is only 2 Watt class A... It heats like a true class A to tweak the listeners ? To be fair, chances are, most users will be using only a couple of watts most of the time, so in practical terms I'd guess it is 'more A than B'. :-) * The volume pot failure is a design failure. Oversight, or perhaps a calculated risk. TBH variable pots all tend to wear out in use, so it is perhaps hard to feel 20-odd years is not enough. It is possible to design and choose components with a view to a longer life, but some luck comes into this, and from the designer's POV they may feel that by then they'll have a better design which they'd prefer you to buy! ;- Above said, I would not personally have arranged the design as they did. However their approach does have some advantages, so this is swings and roundabouts. * Some components (example the caps) are not well suited for the high temperature inside. This again is a trade-off problem. If you want high bias (class A) and a small box, you end up with high temperatures. As you say, some components do not really like this... However dealing with it puts up the price/size/etc... * Users report different failures. * Musical Fidelity feedback is null... That bit is unfortunate if representitive. Better for your wallet, more amusing and satisfying is do some DIY project! I'd agree with that! :-) 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 |
Troubleshooting: amplifier Musical Fidelity A1
In article , Sala Massimo
wrote: Still many thanks for your help. About the A1, what can I say? When I purchased the A1 I was 19 years old, and it seems to me to buy a "Cadillac" (also for the efforts to save the money!). It was really a pleasure to listen to it, with Celestion 5 speakers. Time goes by... I come to the feeling the A1 is a myth: * I thought it is 20 Watt class A, now I read it is only 2 Watt class A... It heats like a true class A to tweak the listeners ? To be fair, chances are, most users will be using only a couple of watts most of the time, so in practical terms I'd guess it is 'more A than B'. :-) * The volume pot failure is a design failure. Oversight, or perhaps a calculated risk. TBH variable pots all tend to wear out in use, so it is perhaps hard to feel 20-odd years is not enough. It is possible to design and choose components with a view to a longer life, but some luck comes into this, and from the designer's POV they may feel that by then they'll have a better design which they'd prefer you to buy! ;- Above said, I would not personally have arranged the design as they did. However their approach does have some advantages, so this is swings and roundabouts. * Some components (example the caps) are not well suited for the high temperature inside. This again is a trade-off problem. If you want high bias (class A) and a small box, you end up with high temperatures. As you say, some components do not really like this... However dealing with it puts up the price/size/etc... * Users report different failures. * Musical Fidelity feedback is null... That bit is unfortunate if representitive. Better for your wallet, more amusing and satisfying is do some DIY project! I'd agree with that! :-) 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 |
Troubleshooting: amplifier Musical Fidelity A1
So? You've obviously had a lot of enjoyment from the A1. Forget the specs
for a minute; do you still enjoy the sound that it makes? If so, why bother whether it is class A up to full power? It's all just numbers - it's your ears that have to be satisfied at the end of the day! Mick, I agree with you until the time the A1 volume pot broke. It sounded good and I was very satisfied. I never stressed the ampli, I used it in a "religious" way, always wired to my Celestion 5 speakers. Now I discover it is not a single failure, other users complain about a bad design. I am very upset. I stop trusting Musical Fidelity. I purchased the A1 for its sound AND for its quality (hi-fi products claims). A1 design quality is worse than many consumer products... so I am wondering about sound quality... it is really a thorn in my side. If you are dissatisfied with the sound, why not build something like the Zen? You can have true class A then. I am thinking about "Death Of Zen" project (funny names...) See Elliott Sound Products, http://sound.westhost.com I appreciate really much his feelings about hi-fi and electronics projects. Take a look at the very interesting web site! ciao, Massimo |
Troubleshooting: amplifier Musical Fidelity A1
So? You've obviously had a lot of enjoyment from the A1. Forget the specs
for a minute; do you still enjoy the sound that it makes? If so, why bother whether it is class A up to full power? It's all just numbers - it's your ears that have to be satisfied at the end of the day! Mick, I agree with you until the time the A1 volume pot broke. It sounded good and I was very satisfied. I never stressed the ampli, I used it in a "religious" way, always wired to my Celestion 5 speakers. Now I discover it is not a single failure, other users complain about a bad design. I am very upset. I stop trusting Musical Fidelity. I purchased the A1 for its sound AND for its quality (hi-fi products claims). A1 design quality is worse than many consumer products... so I am wondering about sound quality... it is really a thorn in my side. If you are dissatisfied with the sound, why not build something like the Zen? You can have true class A then. I am thinking about "Death Of Zen" project (funny names...) See Elliott Sound Products, http://sound.westhost.com I appreciate really much his feelings about hi-fi and electronics projects. Take a look at the very interesting web site! ciao, Massimo |
Troubleshooting: amplifier Musical Fidelity A1
Thanks to all for your help!
I measured the DC voltage accross the pot, at the middle volume: 10 mV on channel, 28 mV the other! How to read these values? The Alps pot is not available in Italy. I searched "stereo" pots, also third parties, on local shops and surplus. They haven't. Perhaps I found the pot at Farnell UK, ALPS RK27111250K (former 0071 50KAX2), Farnell code 697928. Good news: it is £ 16.33 plus shipping cost to ITALY (about £ 8), because Farnell Italy doen't sell to end-users... :-( If anybody can help me to get the pot at a cheaper cost... --- At a first glance, one of the big power caps (10000 uF 25 V) is strange: its plastic dome is going yellow (the other three caps have a transparent dome). Is this a clue of a incoming failure ? ciao, Massimo ITALY (to reply: remove CHIOCCIOLA and PUNTO) |
Troubleshooting: amplifier Musical Fidelity A1
Thanks to all for your help!
I measured the DC voltage accross the pot, at the middle volume: 10 mV on channel, 28 mV the other! How to read these values? The Alps pot is not available in Italy. I searched "stereo" pots, also third parties, on local shops and surplus. They haven't. Perhaps I found the pot at Farnell UK, ALPS RK27111250K (former 0071 50KAX2), Farnell code 697928. Good news: it is £ 16.33 plus shipping cost to ITALY (about £ 8), because Farnell Italy doen't sell to end-users... :-( If anybody can help me to get the pot at a cheaper cost... --- At a first glance, one of the big power caps (10000 uF 25 V) is strange: its plastic dome is going yellow (the other three caps have a transparent dome). Is this a clue of a incoming failure ? ciao, Massimo ITALY (to reply: remove CHIOCCIOLA and PUNTO) |
Troubleshooting: amplifier Musical Fidelity A1
Sala Massimo wrote:
Thanks to all for your help! I measured the DC voltage accross the pot, at the middle volume: 10 mV on channel, 28 mV the other! How to read these values? The Alps pot is not available in Italy. I searched "stereo" pots, also third parties, on local shops and surplus. They haven't. Perhaps I found the pot at Farnell UK, ALPS RK27111250K (former 0071 50KAX2), Farnell code 697928. Good news: it is £ 16.33 plus shipping cost to ITALY (about £ 8), because Farnell Italy doen't sell to end-users... :-( If anybody can help me to get the pot at a cheaper cost... Don't know if its any cheaper, but you could try http://www.hificollective.co.uk/comp...tiometers.html Or I found this link in Italy http://www.audiodesignguide.com/sele/sele.html -- Nick |
Troubleshooting: amplifier Musical Fidelity A1
Sala Massimo wrote:
Thanks to all for your help! I measured the DC voltage accross the pot, at the middle volume: 10 mV on channel, 28 mV the other! How to read these values? The Alps pot is not available in Italy. I searched "stereo" pots, also third parties, on local shops and surplus. They haven't. Perhaps I found the pot at Farnell UK, ALPS RK27111250K (former 0071 50KAX2), Farnell code 697928. Good news: it is £ 16.33 plus shipping cost to ITALY (about £ 8), because Farnell Italy doen't sell to end-users... :-( If anybody can help me to get the pot at a cheaper cost... Don't know if its any cheaper, but you could try http://www.hificollective.co.uk/comp...tiometers.html Or I found this link in Italy http://www.audiodesignguide.com/sele/sele.html -- Nick |
Troubleshooting: amplifier Musical Fidelity A1
In article ,
Sala Massimo wrote: Good news: it is £ 16.33 plus shipping cost to ITALY (about £ 8), because Farnell Italy doen't sell to end-users... :-( If anybody can help me to get the pot at a cheaper cost... Couldn't you order it through a local radio repair shop who have an account with Farnell Italy? -- *Why isn't 11 pronounced onety one? * Dave Plowman London SW 12 RIP Acorn |
Troubleshooting: amplifier Musical Fidelity A1
In article ,
Sala Massimo wrote: Good news: it is £ 16.33 plus shipping cost to ITALY (about £ 8), because Farnell Italy doen't sell to end-users... :-( If anybody can help me to get the pot at a cheaper cost... Couldn't you order it through a local radio repair shop who have an account with Farnell Italy? -- *Why isn't 11 pronounced onety one? * Dave Plowman London SW 12 RIP Acorn |
Troubleshooting: amplifier Musical Fidelity A1
In article , Sala
Massimo wrote: Thanks to all for your help! I measured the DC voltage accross the pot, at the middle volume: 10 mV on channel, 28 mV the other! How to read these values? Not sure what you are asking. If worried that the problem will recur. I would suggest replacing the current pot location with fixed resistors, then then using the new pots in a more conventional fashion as input attenuators. You can then add d.c. break caps to the wipers if you wish as well. A-law 50k pots should still work OK. At a first glance, one of the big power caps (10000 uF 25 V) is strange: its plastic dome is going yellow (the other three caps have a transparent dome). Is this a clue of a incoming failure ? I do not know the capacitors in question, but what you report does not sound good. May be advisible to replace the caps. 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 |
Troubleshooting: amplifier Musical Fidelity A1
In article , Sala
Massimo wrote: Thanks to all for your help! I measured the DC voltage accross the pot, at the middle volume: 10 mV on channel, 28 mV the other! How to read these values? Not sure what you are asking. If worried that the problem will recur. I would suggest replacing the current pot location with fixed resistors, then then using the new pots in a more conventional fashion as input attenuators. You can then add d.c. break caps to the wipers if you wish as well. A-law 50k pots should still work OK. At a first glance, one of the big power caps (10000 uF 25 V) is strange: its plastic dome is going yellow (the other three caps have a transparent dome). Is this a clue of a incoming failure ? I do not know the capacitors in question, but what you report does not sound good. May be advisible to replace the caps. 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 |
Troubleshooting: amplifier Musical Fidelity A1
Sala Massimo wrote:
So? You've obviously had a lot of enjoyment from the A1. Forget the specs for a minute; do you still enjoy the sound that it makes? If so, why bother whether it is class A up to full power? It's all just numbers - it's your ears that have to be satisfied at the end of the day! Mick, I agree with you until the time the A1 volume pot broke. It sounded good and I was very satisfied. I never stressed the ampli, I used it in a "religious" way, always wired to my Celestion 5 speakers. Now I discover it is not a single failure, other users complain about a bad design. I am very upset. I stop trusting Musical Fidelity. I purchased the A1 for its sound AND for its quality (hi-fi products claims). A1 design quality is worse than many consumer products... so I am wondering about sound quality... it is really a thorn in my side. But superficial build quality and engineering quality are two separate things... Look at the new Ferrari Enzo - reports of trim bits falling off in the first few hundred km but the core mechanicals are still well engineered. Closer to the topic, the knobs on my Cyrus 2 lost all their paint within a couple of years but 15 years on the amp still sounds great |
Troubleshooting: amplifier Musical Fidelity A1
Sala Massimo wrote:
So? You've obviously had a lot of enjoyment from the A1. Forget the specs for a minute; do you still enjoy the sound that it makes? If so, why bother whether it is class A up to full power? It's all just numbers - it's your ears that have to be satisfied at the end of the day! Mick, I agree with you until the time the A1 volume pot broke. It sounded good and I was very satisfied. I never stressed the ampli, I used it in a "religious" way, always wired to my Celestion 5 speakers. Now I discover it is not a single failure, other users complain about a bad design. I am very upset. I stop trusting Musical Fidelity. I purchased the A1 for its sound AND for its quality (hi-fi products claims). A1 design quality is worse than many consumer products... so I am wondering about sound quality... it is really a thorn in my side. But superficial build quality and engineering quality are two separate things... Look at the new Ferrari Enzo - reports of trim bits falling off in the first few hundred km but the core mechanicals are still well engineered. Closer to the topic, the knobs on my Cyrus 2 lost all their paint within a couple of years but 15 years on the amp still sounds great |
Troubleshooting: amplifier Musical Fidelity A1
On Fri, 19 Dec 2003 06:08:14 -0800, Sala Massimo wrote:
snip Mick, I agree with you until the time the A1 volume pot broke. It sounded good and I was very satisfied. I never stressed the ampli, I used it in a "religious" way, always wired to my Celestion 5 speakers. Now I discover it is not a single failure, other users complain about a bad design. I am very upset. I stop trusting Musical Fidelity. I purchased the A1 for its sound AND for its quality (hi-fi products claims). A1 design quality is worse than many consumer products... so I am wondering about sound quality... it is really a thorn in my side. If you are dissatisfied with the sound, why not build something like the Zen? You can have true class A then. I am thinking about "Death Of Zen" project (funny names...) See Elliott Sound Products, http://sound.westhost.com I appreciate really much his feelings about hi-fi and electronics projects. Take a look at the very interesting web site! Yep - I like that site! This is an interesting one too - he has replaced the preamp in an A1 with a more conventional one: http://www.mhennessy.f9.co.uk/mf_a1/#construction I'm just experimenting with a source-follower single-ended MOSFET headphone amp, with an op-amp voltage gain stage. Its rather good but not enough output (yet!) for speakers. :-) -- Mick http://www.nascom.info for Nascom & Gemini information Also at http://www.mixtel.co.uk where the collection started. Currently deserting M$ for linux... :-) |
Troubleshooting: amplifier Musical Fidelity A1
On Fri, 19 Dec 2003 06:08:14 -0800, Sala Massimo wrote:
snip Mick, I agree with you until the time the A1 volume pot broke. It sounded good and I was very satisfied. I never stressed the ampli, I used it in a "religious" way, always wired to my Celestion 5 speakers. Now I discover it is not a single failure, other users complain about a bad design. I am very upset. I stop trusting Musical Fidelity. I purchased the A1 for its sound AND for its quality (hi-fi products claims). A1 design quality is worse than many consumer products... so I am wondering about sound quality... it is really a thorn in my side. If you are dissatisfied with the sound, why not build something like the Zen? You can have true class A then. I am thinking about "Death Of Zen" project (funny names...) See Elliott Sound Products, http://sound.westhost.com I appreciate really much his feelings about hi-fi and electronics projects. Take a look at the very interesting web site! Yep - I like that site! This is an interesting one too - he has replaced the preamp in an A1 with a more conventional one: http://www.mhennessy.f9.co.uk/mf_a1/#construction I'm just experimenting with a source-follower single-ended MOSFET headphone amp, with an op-amp voltage gain stage. Its rather good but not enough output (yet!) for speakers. :-) -- Mick http://www.nascom.info for Nascom & Gemini information Also at http://www.mixtel.co.uk where the collection started. Currently deserting M$ for linux... :-) |
Troubleshooting: amplifier Musical Fidelity A1
Form@C wrote:
I'm just experimenting with a source-follower single-ended MOSFET headphone amp, with an op-amp voltage gain stage. Its rather good but not enough output (yet!) for speakers. :-) You could always try a gainclone http://home.student.utwente.nl/f.s.b...rtedLM3875.gif -- Nick |
Troubleshooting: amplifier Musical Fidelity A1
Form@C wrote:
I'm just experimenting with a source-follower single-ended MOSFET headphone amp, with an op-amp voltage gain stage. Its rather good but not enough output (yet!) for speakers. :-) You could always try a gainclone http://home.student.utwente.nl/f.s.b...rtedLM3875.gif -- Nick |
Troubleshooting: amplifier Musical Fidelity A1
On Fri, 19 Dec 2003 18:35:41 +0000, Nick Gorham wrote:
Form@C wrote: I'm just experimenting with a source-follower single-ended MOSFET headphone amp, with an op-amp voltage gain stage. Its rather good but not enough output (yet!) for speakers. :-) You could always try a gainclone http://home.student.utwente.nl/f.s.b...rtedLM3875.gif I *could*, but I rather like the look of something like this: http://digilander.libero.it/essentia...ybrid_home.htm 'cos I suspect it has more chance of *really* sounding good, rather than being based around a chip being used for other than its designed purpose! (ducks down behind 0.2C/W heatsinks to hide from gaincloners hurling flaming 1000uF capacitors...) :-) -- Mick http://www.nascom.info for Nascom & Gemini information Also at http://www.mixtel.co.uk where the collection started. Currently deserting M$ for linux... :-) |
Troubleshooting: amplifier Musical Fidelity A1
On Fri, 19 Dec 2003 18:35:41 +0000, Nick Gorham wrote:
Form@C wrote: I'm just experimenting with a source-follower single-ended MOSFET headphone amp, with an op-amp voltage gain stage. Its rather good but not enough output (yet!) for speakers. :-) You could always try a gainclone http://home.student.utwente.nl/f.s.b...rtedLM3875.gif I *could*, but I rather like the look of something like this: http://digilander.libero.it/essentia...ybrid_home.htm 'cos I suspect it has more chance of *really* sounding good, rather than being based around a chip being used for other than its designed purpose! (ducks down behind 0.2C/W heatsinks to hide from gaincloners hurling flaming 1000uF capacitors...) :-) -- Mick http://www.nascom.info for Nascom & Gemini information Also at http://www.mixtel.co.uk where the collection started. Currently deserting M$ for linux... :-) |
Troubleshooting: amplifier Musical Fidelity A1
Form@C wrote:
On Fri, 19 Dec 2003 18:35:41 +0000, Nick Gorham wrote: Form@C wrote: I'm just experimenting with a source-follower single-ended MOSFET headphone amp, with an op-amp voltage gain stage. Its rather good but not enough output (yet!) for speakers. :-) You could always try a gainclone http://home.student.utwente.nl/f.s.b...rtedLM3875.gif I *could*, but I rather like the look of something like this: http://digilander.libero.it/essentia...ybrid_home.htm 'cos I suspect it has more chance of *really* sounding good, rather than being based around a chip being used for other than its designed purpose! (ducks down behind 0.2C/W heatsinks to hide from gaincloners hurling flaming 1000uF capacitors...) :-) Well you could try this then http://www.petemoore.pwp.blueyonder....rschematic.jpg I didn't see the need as the one I built was being fed by a valve stage anyway. They are fun things, I was quite shocked just how good they are for £30. Of course you could go to the other extreme. http://www.lurcher.org/nick/audio/vi...ul/v4212-1.jpg :-) -- Nick |
Troubleshooting: amplifier Musical Fidelity A1
Form@C wrote:
On Fri, 19 Dec 2003 18:35:41 +0000, Nick Gorham wrote: Form@C wrote: I'm just experimenting with a source-follower single-ended MOSFET headphone amp, with an op-amp voltage gain stage. Its rather good but not enough output (yet!) for speakers. :-) You could always try a gainclone http://home.student.utwente.nl/f.s.b...rtedLM3875.gif I *could*, but I rather like the look of something like this: http://digilander.libero.it/essentia...ybrid_home.htm 'cos I suspect it has more chance of *really* sounding good, rather than being based around a chip being used for other than its designed purpose! (ducks down behind 0.2C/W heatsinks to hide from gaincloners hurling flaming 1000uF capacitors...) :-) Well you could try this then http://www.petemoore.pwp.blueyonder....rschematic.jpg I didn't see the need as the one I built was being fed by a valve stage anyway. They are fun things, I was quite shocked just how good they are for £30. Of course you could go to the other extreme. http://www.lurcher.org/nick/audio/vi...ul/v4212-1.jpg :-) -- Nick |
Troubleshooting: amplifier Musical Fidelity A1
Form@C wrote:
On Fri, 19 Dec 2003 18:35:41 +0000, Nick Gorham wrote: Form@C wrote: I'm just experimenting with a source-follower single-ended MOSFET headphone amp, with an op-amp voltage gain stage. Its rather good but not enough output (yet!) for speakers. :-) You could always try a gainclone http://home.student.utwente.nl/f.s.b...rtedLM3875.gif Strange design. Linear taper volume control, only 1000uF supply smoothing for a chip than can output 56 watts and why throw away all the loudspeaker damping by inserting a series resistor? And if it is a phones amp why use such a meaty chip? Ian |
Troubleshooting: amplifier Musical Fidelity A1
Form@C wrote:
On Fri, 19 Dec 2003 18:35:41 +0000, Nick Gorham wrote: Form@C wrote: I'm just experimenting with a source-follower single-ended MOSFET headphone amp, with an op-amp voltage gain stage. Its rather good but not enough output (yet!) for speakers. :-) You could always try a gainclone http://home.student.utwente.nl/f.s.b...rtedLM3875.gif Strange design. Linear taper volume control, only 1000uF supply smoothing for a chip than can output 56 watts and why throw away all the loudspeaker damping by inserting a series resistor? And if it is a phones amp why use such a meaty chip? Ian |
Troubleshooting: amplifier Musical Fidelity A1
Ian Bell wrote:
Form@C wrote: On Fri, 19 Dec 2003 18:35:41 +0000, Nick Gorham wrote: Form@C wrote: I'm just experimenting with a source-follower single-ended MOSFET headphone amp, with an op-amp voltage gain stage. Its rather good but not enough output (yet!) for speakers. :-) You could always try a gainclone http://home.student.utwente.nl/f.s.b...rtedLM3875.gif Strange design. Linear taper volume control, only 1000uF supply smoothing for a chip than can output 56 watts and why throw away all the loudspeaker damping by inserting a series resistor? And if it is a phones amp why use such a meaty chip? Ian The original post said "not enough output (yet!) for speakers" so it wasn't a suggestion for a headphone amp. The lin pot is used as its in the feedback loop, and in conjunction with the next R provides a log (ish) response. The 1000uf, is because they sound better with less cap's, the design is all about speed, and bigger caps seem to produce a more sluggish result. The R22 is because no one trusts these amps at first to connect to their speakers. Its not just a bad design, its all done for a reason, maybe not a normal or even good reason, but a reason never the less. -- Nick |
Troubleshooting: amplifier Musical Fidelity A1
Ian Bell wrote:
Form@C wrote: On Fri, 19 Dec 2003 18:35:41 +0000, Nick Gorham wrote: Form@C wrote: I'm just experimenting with a source-follower single-ended MOSFET headphone amp, with an op-amp voltage gain stage. Its rather good but not enough output (yet!) for speakers. :-) You could always try a gainclone http://home.student.utwente.nl/f.s.b...rtedLM3875.gif Strange design. Linear taper volume control, only 1000uF supply smoothing for a chip than can output 56 watts and why throw away all the loudspeaker damping by inserting a series resistor? And if it is a phones amp why use such a meaty chip? Ian The original post said "not enough output (yet!) for speakers" so it wasn't a suggestion for a headphone amp. The lin pot is used as its in the feedback loop, and in conjunction with the next R provides a log (ish) response. The 1000uf, is because they sound better with less cap's, the design is all about speed, and bigger caps seem to produce a more sluggish result. The R22 is because no one trusts these amps at first to connect to their speakers. Its not just a bad design, its all done for a reason, maybe not a normal or even good reason, but a reason never the less. -- Nick |
Troubleshooting: amplifier Musical Fidelity A1
On Sat, 20 Dec 2003 11:34:40 +0000, Nick Gorham wrote:
snip Well you could try this then http://www.petemoore.pwp.blueyonder....rschematic.jpg I didn't see the need as the one I built was being fed by a valve stage anyway. They are fun things, I was quite shocked just how good they are for £30. Of course you could go to the other extreme. Now - there's an idea.... :-) http://www.lurcher.org/nick/audio/vi...ul/v4212-1.jpg :-) I'm *really* jealous now... I've always wanted a pair of 211s to play with! (with the appropriate ironmongery that is!). :-) That's a hell of a setup! (plus obligatory !!!!!! courtesy of ebay) I particularly like the king-size timber & ply chassis system.... -- Mick http://www.nascom.info for Nascom & Gemini information Also at http://www.mixtel.co.uk where the collection started. Currently deserting M$ for linux... :-) |
Troubleshooting: amplifier Musical Fidelity A1
On Sat, 20 Dec 2003 11:34:40 +0000, Nick Gorham wrote:
snip Well you could try this then http://www.petemoore.pwp.blueyonder....rschematic.jpg I didn't see the need as the one I built was being fed by a valve stage anyway. They are fun things, I was quite shocked just how good they are for £30. Of course you could go to the other extreme. Now - there's an idea.... :-) http://www.lurcher.org/nick/audio/vi...ul/v4212-1.jpg :-) I'm *really* jealous now... I've always wanted a pair of 211s to play with! (with the appropriate ironmongery that is!). :-) That's a hell of a setup! (plus obligatory !!!!!! courtesy of ebay) I particularly like the king-size timber & ply chassis system.... -- Mick http://www.nascom.info for Nascom & Gemini information Also at http://www.mixtel.co.uk where the collection started. Currently deserting M$ for linux... :-) |
Troubleshooting: amplifier Musical Fidelity A1
Form@C wrote:
On Sat, 20 Dec 2003 11:34:40 +0000, Nick Gorham wrote: snip Well you could try this then http://www.petemoore.pwp.blueyonder....rschematic.jpg I didn't see the need as the one I built was being fed by a valve stage anyway. They are fun things, I was quite shocked just how good they are for £30. Of course you could go to the other extreme. Now - there's an idea.... :-) http://www.lurcher.org/nick/audio/vi...ul/v4212-1.jpg :-) I'm *really* jealous now... I've always wanted a pair of 211s to play with! (with the appropriate ironmongery that is!). :-) That's a hell of a setup! (plus obligatory !!!!!! courtesy of ebay) I particularly like the king-size timber & ply chassis system.... Sadly not mine, and no its not at 211, its a 212 (and assorted variants). one day I may get to play with toys like that, but first stage 6em7. For comparison, this pic is a ecc83 on the left, the next is a 211, and then various 212 (ish) valves, Paul would go into great and interesting depth about the differences. And under them all a GM100. http://www.lurcher.org/nick/audio/vi...l/v4212-20.jpg -- Nick |
Troubleshooting: amplifier Musical Fidelity A1
Form@C wrote:
On Sat, 20 Dec 2003 11:34:40 +0000, Nick Gorham wrote: snip Well you could try this then http://www.petemoore.pwp.blueyonder....rschematic.jpg I didn't see the need as the one I built was being fed by a valve stage anyway. They are fun things, I was quite shocked just how good they are for £30. Of course you could go to the other extreme. Now - there's an idea.... :-) http://www.lurcher.org/nick/audio/vi...ul/v4212-1.jpg :-) I'm *really* jealous now... I've always wanted a pair of 211s to play with! (with the appropriate ironmongery that is!). :-) That's a hell of a setup! (plus obligatory !!!!!! courtesy of ebay) I particularly like the king-size timber & ply chassis system.... Sadly not mine, and no its not at 211, its a 212 (and assorted variants). one day I may get to play with toys like that, but first stage 6em7. For comparison, this pic is a ecc83 on the left, the next is a 211, and then various 212 (ish) valves, Paul would go into great and interesting depth about the differences. And under them all a GM100. http://www.lurcher.org/nick/audio/vi...l/v4212-20.jpg -- Nick |
Troubleshooting: amplifier Musical Fidelity A1
On Sat, 20 Dec 2003 22:03:11 +0000, Nick Gorham wrote:
snip Sadly not mine, and no its not at 211, its a 212 (and assorted variants). one day I may get to play with toys like that, but first stage 6em7. For comparison, this pic is a ecc83 on the left, the next is a 211, and then various 212 (ish) valves, Paul would go into great and interesting depth about the differences. And under them all a GM100. http://www.lurcher.org/nick/audio/vi...l/v4212-20.jpg wow! That is serious glassware... I assume that the GM100 isn't for a preamp then.... Sheesh! :-) Much as I love Paul's collection of heavy-duty audio, It can only be regarded as an interesting conversation piece when installed like that. It doesn't exactly blend in with the decor does it? grin Lovely - my Mrs would kill me... Especially now I've found this pic: http://www.lurcher.org/nick/audio/vi...paul/paul1.jpg I've dug my old 6L6 p-p project out again. I may just get to complete it soon! My nasty little parallelled ECC82 p-p amp still runs nicely, but there is a bit of a hum on one channel that needs looking at. Low power, but interesting; and a lot cooler and lighter than a 212 collection. Takes less juice in total than the heater on one of those... (photos on mixtel site under Rough Audio). -- Mick http://www.nascom.info for Nascom & Gemini information Also at http://www.mixtel.co.uk where the collection started. Currently deserting M$ for linux... :-) |
Troubleshooting: amplifier Musical Fidelity A1
On Sat, 20 Dec 2003 22:03:11 +0000, Nick Gorham wrote:
snip Sadly not mine, and no its not at 211, its a 212 (and assorted variants). one day I may get to play with toys like that, but first stage 6em7. For comparison, this pic is a ecc83 on the left, the next is a 211, and then various 212 (ish) valves, Paul would go into great and interesting depth about the differences. And under them all a GM100. http://www.lurcher.org/nick/audio/vi...l/v4212-20.jpg wow! That is serious glassware... I assume that the GM100 isn't for a preamp then.... Sheesh! :-) Much as I love Paul's collection of heavy-duty audio, It can only be regarded as an interesting conversation piece when installed like that. It doesn't exactly blend in with the decor does it? grin Lovely - my Mrs would kill me... Especially now I've found this pic: http://www.lurcher.org/nick/audio/vi...paul/paul1.jpg I've dug my old 6L6 p-p project out again. I may just get to complete it soon! My nasty little parallelled ECC82 p-p amp still runs nicely, but there is a bit of a hum on one channel that needs looking at. Low power, but interesting; and a lot cooler and lighter than a 212 collection. Takes less juice in total than the heater on one of those... (photos on mixtel site under Rough Audio). -- Mick http://www.nascom.info for Nascom & Gemini information Also at http://www.mixtel.co.uk where the collection started. Currently deserting M$ for linux... :-) |
Troubleshooting: amplifier Musical Fidelity A1
Form@C wrote:
I assume that the GM100 isn't for a preamp then.... Sheesh! :-) There was a actual working amp using them at VSAC http://img.audioasylum.com/cgi/i.pl?...f=MVC-001F.JPG Much as I love Paul's collection of heavy-duty audio, It can only be regarded as an interesting conversation piece when installed like that. It doesn't exactly blend in with the decor does it? grin Lovely - my Mrs would kill me... Especially now I've found this pic: http://www.lurcher.org/nick/audio/vi...paul/paul1.jpg Its still a work in progress, he does have plans to make it into two monoblocks, that can be put in the back of a van. I've dug my old 6L6 p-p project out again. I may just get to complete it soon! My nasty little parallelled ECC82 p-p amp still runs nicely, but there is a bit of a hum on one channel that needs looking at. Low power, but interesting; and a lot cooler and lighter than a 212 collection. Takes less juice in total than the heater on one of those... (photos on mixtel site under Rough Audio). As I said, I have yet to build a SE amp, but after hearing the amps in the pictures, I am going to give it a try, there was a nice sounding 6em7 amp there, (sort of rat amp construction), so I am going to give that a try in the new year. http://www.lurcher.org/nick/audio/vi...ul/v6em7-1.jpg -- Nick |
Troubleshooting: amplifier Musical Fidelity A1
Form@C wrote:
I assume that the GM100 isn't for a preamp then.... Sheesh! :-) There was a actual working amp using them at VSAC http://img.audioasylum.com/cgi/i.pl?...f=MVC-001F.JPG Much as I love Paul's collection of heavy-duty audio, It can only be regarded as an interesting conversation piece when installed like that. It doesn't exactly blend in with the decor does it? grin Lovely - my Mrs would kill me... Especially now I've found this pic: http://www.lurcher.org/nick/audio/vi...paul/paul1.jpg Its still a work in progress, he does have plans to make it into two monoblocks, that can be put in the back of a van. I've dug my old 6L6 p-p project out again. I may just get to complete it soon! My nasty little parallelled ECC82 p-p amp still runs nicely, but there is a bit of a hum on one channel that needs looking at. Low power, but interesting; and a lot cooler and lighter than a 212 collection. Takes less juice in total than the heater on one of those... (photos on mixtel site under Rough Audio). As I said, I have yet to build a SE amp, but after hearing the amps in the pictures, I am going to give it a try, there was a nice sounding 6em7 amp there, (sort of rat amp construction), so I am going to give that a try in the new year. http://www.lurcher.org/nick/audio/vi...ul/v6em7-1.jpg -- Nick |
Troubleshooting: amplifier Musical Fidelity A1
In article , Nick Gorham
wrote: Ian Bell wrote: http://home.student.utwente.nl/f.s.b...rtedLM3875.gif The original post said "not enough output (yet!) for speakers" so it wasn't a suggestion for a headphone amp. The lin pot is used as its in the feedback loop, and in conjunction with the next R provides a log (ish) response. Well, the pot does interact with the loop, but it isn't a design I'd choose. I'd need to look at it in practice to be sure, but the design rings alarm bells with me regarding things like noise, bandwidth, and instability. The 1000uf, is because they sound better with less cap's, the design is all about speed, and bigger caps seem to produce a more sluggish result. I find that baffling. The caps mean that if you were drawing about an Amp (reasonable enough for a power amp) the ripple would be of the order of 10V. Since the rail is only of the order of 30V that is a hell of a lot. Ideally, the amp should ignore power line variations below those that make it clip. However if it does, then the size of the cap should not have any effect upon the sound, and it would not be possible to say its sound was affected by the choice of capacitor size. If the cap size *does* affect the sound it implies that the amp is either sensitive to the rail variations, or is clipping. Clipping should be self-evidently bad news. Sensitivity to rail variations implies that you will be leaking ripple and d.c. variations onto the signal output in a level dependent manner. It may also mean distortion is transferred from the rails to the output. Also distorted crosstalk for stereo. Do some people like their music with 'added ripple, distortion, and d.c. LF fluctuations'? If so, then that may be OK. However it doesn't seem much like good audio to me. The R22 is because no one trusts these amps at first to connect to their speakers. 0.22 Ohms is too low to add much to the stability margin. Also not much use as a short-term current limiter, although it will presumably fuse after a while. (However that may not be relevant given the 1000 microF caps as these imply almost no long-term current sustainability.) High enough to alter the frequency response in a speaker-dependent manner, though. Its not just a bad design, its all done for a reason, maybe not a normal or even good reason, but a reason never the less. I'm afraid it does not look much a like a *good* design to me. :-/ Unless you want added ripple, possible instability, noise, added LF variations, gain dependent bandwidth, and not much sustained power. This does not seem like 'speed' to me. 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 |
Troubleshooting: amplifier Musical Fidelity A1
In article , Nick Gorham
wrote: Ian Bell wrote: http://home.student.utwente.nl/f.s.b...rtedLM3875.gif The original post said "not enough output (yet!) for speakers" so it wasn't a suggestion for a headphone amp. The lin pot is used as its in the feedback loop, and in conjunction with the next R provides a log (ish) response. Well, the pot does interact with the loop, but it isn't a design I'd choose. I'd need to look at it in practice to be sure, but the design rings alarm bells with me regarding things like noise, bandwidth, and instability. The 1000uf, is because they sound better with less cap's, the design is all about speed, and bigger caps seem to produce a more sluggish result. I find that baffling. The caps mean that if you were drawing about an Amp (reasonable enough for a power amp) the ripple would be of the order of 10V. Since the rail is only of the order of 30V that is a hell of a lot. Ideally, the amp should ignore power line variations below those that make it clip. However if it does, then the size of the cap should not have any effect upon the sound, and it would not be possible to say its sound was affected by the choice of capacitor size. If the cap size *does* affect the sound it implies that the amp is either sensitive to the rail variations, or is clipping. Clipping should be self-evidently bad news. Sensitivity to rail variations implies that you will be leaking ripple and d.c. variations onto the signal output in a level dependent manner. It may also mean distortion is transferred from the rails to the output. Also distorted crosstalk for stereo. Do some people like their music with 'added ripple, distortion, and d.c. LF fluctuations'? If so, then that may be OK. However it doesn't seem much like good audio to me. The R22 is because no one trusts these amps at first to connect to their speakers. 0.22 Ohms is too low to add much to the stability margin. Also not much use as a short-term current limiter, although it will presumably fuse after a while. (However that may not be relevant given the 1000 microF caps as these imply almost no long-term current sustainability.) High enough to alter the frequency response in a speaker-dependent manner, though. Its not just a bad design, its all done for a reason, maybe not a normal or even good reason, but a reason never the less. I'm afraid it does not look much a like a *good* design to me. :-/ Unless you want added ripple, possible instability, noise, added LF variations, gain dependent bandwidth, and not much sustained power. This does not seem like 'speed' to me. 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 |
Troubleshooting: amplifier Musical Fidelity A1
On Sun, 21 Dec 2003 10:28:02 +0000, Nick Gorham wrote:
Form@C wrote: I assume that the GM100 isn't for a preamp then.... Sheesh! :-) There was a actual working amp using them at VSAC http://img.audioasylum.com/cgi/i.pl?...f=MVC-001F.JPG Now that is an AMP 7/8ths !!!!!!!!! snip Its still a work in progress, he does have plans to make it into two monoblocks, that can be put in the back of a van. He could build on one chassis - and put the wheels and a tow bar straight on... :-) snip As I said, I have yet to build a SE amp, but after hearing the amps in the pictures, I am going to give it a try, there was a nice sounding 6em7 amp there, (sort of rat amp construction), so I am going to give that a try in the new year. http://www.lurcher.org/nick/audio/vi...ul/v6em7-1.jpg I've been digging in the shed again, and come up with a couple of nondescript SE OPTs, a couple of Sovtek 6L6GCs, a few assorted 6SN7s and a 6SL7. I feel the urge to build SE again... :-) Pity there's no mains tranny bigger than 60mA in there :-( Now - where's the plywood... -- Mick http://www.nascom.info for Nascom & Gemini information Also at http://www.mixtel.co.uk where the collection started. Currently deserting M$ for linux... :-) |
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