I need to build a supply for 40vdc and 1.5A
It is for a SE Class A SS amp.
Hum and ripple less than 5mV.
What should I do??
I do have 4 68,000uF 50v caps... but wary to use them due to charging currents.
I am looking for a good schematic for both a shunt and a series regulator that would work for this application.
Of course looking for the best sonic way of doing it.
Thanks!!!
It is for a SE Class A SS amp.
Hum and ripple less than 5mV.
What should I do??
I do have 4 68,000uF 50v caps... but wary to use them due to charging currents.
I am looking for a good schematic for both a shunt and a series regulator that would work for this application.
Of course looking for the best sonic way of doing it.
Thanks!!!
AudioGeek said:
I don't know if any practical passive set-up will ever get to that level of ripple / hum. You can either use regulators which may not be sonically as good, or you can ask yourself if you really need that kind of ripple / hum.
I would imagine most amps have reasonably good psrr (>40db?). how much does that translate 5mv ripples on the rail into ripples on the output? does that really matter in your application?
If the design is PP, then PSRR will be considerable anyway and 10-15mV of ripple is mere bagatelle.......
If the design is SE, then assuming the output is the source or emitter, then the high drain/collector impedance will ensure the ripple has little effect.
Exactly as Millwood says, active regulators tend NOT to sound marvellous, but passive power supplies do, because there is no feedback loop to synthesize intermodulation products. In any event precise regulation of voltage is not required. Impedance characteristics with frequency are far more important.
You need to build it, listen to it, figure out cause and effect, and get right away from the figures until you can prove the parameters you are measuring are a problem.
PSUD/PSpice etc are useful tools, but akin to reading about car repair in a manual, while the car sits broken in your garage. I am well aware that it is de rigeur to operate these programs with flexibility and math knowledge, but nothing can demonstrate the causal links like building and listening.
Cheers,
Hugh
If the design is SE, then assuming the output is the source or emitter, then the high drain/collector impedance will ensure the ripple has little effect.
Exactly as Millwood says, active regulators tend NOT to sound marvellous, but passive power supplies do, because there is no feedback loop to synthesize intermodulation products. In any event precise regulation of voltage is not required. Impedance characteristics with frequency are far more important.
You need to build it, listen to it, figure out cause and effect, and get right away from the figures until you can prove the parameters you are measuring are a problem.
PSUD/PSpice etc are useful tools, but akin to reading about car repair in a manual, while the car sits broken in your garage. I am well aware that it is de rigeur to operate these programs with flexibility and math knowledge, but nothing can demonstrate the causal links like building and listening.
Cheers,
Hugh
Hi PD,
Thank you for your post.
I did tests on the Ultra fast Soft Recovery diodes, and found them to be sonically far superior to a conventiional bridge. Others have tried Schottkys, and the Fairchild diodes, but not me. If you use a choke and a reasonable quality second cap (CLC) then the spikes are pretty small.
I know what you are saying about amps which are susceptible to high ripple, but SE amps are pretty good, Pavel, and they have low PSRR!!
Beware categoric statements, some !@#$ always proves you wrong!
I've tried capacitance multipliers. They enhance the capacitive smoothing effect by use of active devices. But the active devices do impose their own sound on the proceedings, and I seem to get better results with the real thing........
Cheers,
Hugh
Thank you for your post.
I did tests on the Ultra fast Soft Recovery diodes, and found them to be sonically far superior to a conventiional bridge. Others have tried Schottkys, and the Fairchild diodes, but not me. If you use a choke and a reasonable quality second cap (CLC) then the spikes are pretty small.
I know what you are saying about amps which are susceptible to high ripple, but SE amps are pretty good, Pavel, and they have low PSRR!!
Beware categoric statements, some !@#$ always proves you wrong!
I've tried capacitance multipliers. They enhance the capacitive smoothing effect by use of active devices. But the active devices do impose their own sound on the proceedings, and I seem to get better results with the real thing........
Cheers,
Hugh
Hi Hugh, I know how work CLC filter, in my regulated supply I have it too. SE amps are maybe good sonicaly, but I claim, that amp should have good PSR and if haven't it, is in my look wrong. And on which parameter of amp cause high speed diodes ? I have in my amps SNR over 120 dB ( A ), respectively over 115 dB linear, with normal bridges. What can I to get better with this ? I like clear explanation 
.
.
Not that it matters but.........
"And on which parameter of amp cause high speed diodes ?"
The listening parameter. Do a search on the forum as this has been disscussed extensively. People have been using high speed soft recovery diodes for audio for well over a decade. The soft recovery generates much less RFI than the conventional bridge rectifiers that are commonly used. most amplifiers have pretty bad PSRR at RF frequencies. These RF components can couple through inductors via the capacitance between windings. CLC filtering may not be an effective solution for RFI in the power supply.
"And on which parameter of amp cause high speed diodes ?"
The listening parameter. Do a search on the forum as this has been disscussed extensively. People have been using high speed soft recovery diodes for audio for well over a decade. The soft recovery generates much less RFI than the conventional bridge rectifiers that are commonly used. most amplifiers have pretty bad PSRR at RF frequencies. These RF components can couple through inductors via the capacitance between windings. CLC filtering may not be an effective solution for RFI in the power supply.
PD,
As you are well aware, I'm not an engineer, fer crissakes, just a talented amateur. All my assessments are based on listening tests - just like the consumer. I find that the subjectives are king every time, they determine whether people will shell out hard cash to buy the product, NOT the figures, though there are many who still buy on figures, but their numbers are statistically small. I'm very impressed with 120dB S/N, Pavel, very impressive indeed, but DOES IT SOUND BETTER? It probably does, because the noise floor is very low, but you really are asking the wrong man.
I take a philistine pride in producing products which sound good. To my surprise, in December 2002 a customer measured my amp's distortion at full load across the audio band and it was incredibly low; I must have got something right, but I never consciously set out to achieve this, my goal was a good sound. I regard amp design as a detective regards a murder case; it is all based on hunches, exhaustively followed up with listening tests. Of course, I have a selection of good DMMs, and a 100MHz CRO, but this is merely Stage 1. Stage 2 is listening tests, and stage 3 is customer acceptance.
So, accordingly, I suggest the question should be this:
'Many consumers have reported improved sound using UFSR diodes in amplifier power supplies. What diode parameters might explain this phenomenon?'
I would contend that there are many subtle effects in audio which are well known in the folklore but for which an explanation in engineering terms is, at this stage, unknown. Should not attempts be made to isolate and pin down these phenomena in terms of measured parameters? I really see it this way:
1. Subjectively observed phenomenon
2. Blind test confirmation of phenomenon
3. 'Brainstorm' of possible causes.
4. Investigation using psycho-auditory measurement.
5. Analysis of results.
6. Correlation with measureable parameters of components and system specifications.
Cheers,
Hugh
As you are well aware, I'm not an engineer, fer crissakes, just a talented amateur. All my assessments are based on listening tests - just like the consumer. I find that the subjectives are king every time, they determine whether people will shell out hard cash to buy the product, NOT the figures, though there are many who still buy on figures, but their numbers are statistically small. I'm very impressed with 120dB S/N, Pavel, very impressive indeed, but DOES IT SOUND BETTER? It probably does, because the noise floor is very low, but you really are asking the wrong man.
I take a philistine pride in producing products which sound good. To my surprise, in December 2002 a customer measured my amp's distortion at full load across the audio band and it was incredibly low; I must have got something right, but I never consciously set out to achieve this, my goal was a good sound. I regard amp design as a detective regards a murder case; it is all based on hunches, exhaustively followed up with listening tests. Of course, I have a selection of good DMMs, and a 100MHz CRO, but this is merely Stage 1. Stage 2 is listening tests, and stage 3 is customer acceptance.
So, accordingly, I suggest the question should be this:
'Many consumers have reported improved sound using UFSR diodes in amplifier power supplies. What diode parameters might explain this phenomenon?'
I would contend that there are many subtle effects in audio which are well known in the folklore but for which an explanation in engineering terms is, at this stage, unknown. Should not attempts be made to isolate and pin down these phenomena in terms of measured parameters? I really see it this way:
1. Subjectively observed phenomenon
2. Blind test confirmation of phenomenon
3. 'Brainstorm' of possible causes.
4. Investigation using psycho-auditory measurement.
5. Analysis of results.
6. Correlation with measureable parameters of components and system specifications.
Cheers,
Hugh
Hmm it is interesting to see two experts discussing amps by
seeing it from contradictive angles. I'm surprised that someone
like Hugh have such a perspective. I thought such perspective
only apply to the unknowledgable like me
When I saw DPA amplifiers (especially the one with Hitachi mosfets),
I thought that Pavel had done anything to make good "numbers" as
dictated by theories. The error correction circuit is probably
okay but small caps between MOSFETs pins, the double boucherots, etc.
I had one opinion though that justifies Pavel's approach, and that's
only my opinion. I think that amplifier is just amplifier. It is not
as critical as speakers. It is silly how ones cannot differentiate
the "sound" improvement of an expensive amp over a cheap amp. But
give him a good speaker and see if he thinks that a cheap speaker
sounds better or equal with expensive one.
With other components perfect (speaker and source), I believe that
Pavel's approach is more relevant, because we don't need the amp to
HELP the other components. But the fact is most DIYers have far from
perfect components. (IMO, the EI vs torroid also has the same issue).
BTW, IMO most beginners will like the sound of Alephs amplifiers. And
I see Nelson Pass more like psycholog or philosopher than technician.
But very experienced builders/listeners tend to have preference like
that of Destroyer-X. It is not surprising to me that Destroyer-X had
suspected that AKSA amp is "the one" only from knowing the designer's
thinking.
seeing it from contradictive angles. I'm surprised that someone
like Hugh have such a perspective. I thought such perspective
only apply to the unknowledgable like me
When I saw DPA amplifiers (especially the one with Hitachi mosfets),
I thought that Pavel had done anything to make good "numbers" as
dictated by theories. The error correction circuit is probably
okay but small caps between MOSFETs pins, the double boucherots, etc.
I had one opinion though that justifies Pavel's approach, and that's
only my opinion. I think that amplifier is just amplifier. It is not
as critical as speakers. It is silly how ones cannot differentiate
the "sound" improvement of an expensive amp over a cheap amp. But
give him a good speaker and see if he thinks that a cheap speaker
sounds better or equal with expensive one.
With other components perfect (speaker and source), I believe that
Pavel's approach is more relevant, because we don't need the amp to
HELP the other components. But the fact is most DIYers have far from
perfect components. (IMO, the EI vs torroid also has the same issue).
BTW, IMO most beginners will like the sound of Alephs amplifiers. And
I see Nelson Pass more like psycholog or philosopher than technician.
But very experienced builders/listeners tend to have preference like
that of Destroyer-X. It is not surprising to me that Destroyer-X had
suspected that AKSA amp is "the one" only from knowing the designer's
thinking.
Hugh,
all of the problem is that me or you never had a chance to compare directly AKSA and DPA. PD and me only heard amps of very similar topology as AKSA. So the long distance exchange of pressumptions is useless, IMHO.
I can only tell that DPA sounds very, very good, in case that it is connected in a high quality audio chain. I cannot say the same about the amps with similar topology as AKSA. But they were not the original AKSA's, of course.
Cheers, Pavel
all of the problem is that me or you never had a chance to compare directly AKSA and DPA. PD and me only heard amps of very similar topology as AKSA. So the long distance exchange of pressumptions is useless, IMHO.
I can only tell that DPA sounds very, very good, in case that it is connected in a high quality audio chain. I cannot say the same about the amps with similar topology as AKSA. But they were not the original AKSA's, of course.
Cheers, Pavel
Jay, surely anything that preceeds the speakers is the 'source' from the speakers point of view. If that source material is flawed then the sound produced by the speakers will reflect that ( as well as adding their own 'signature' to the music).
I was recently trying out some new Dynaudio speakers at a local dealers. The Naim pre-power combo they were using seemed unable to deal with bass guitar when played though the Dynaudios. We checked all parts of the system and found no fault with the individual parts, just that combination. In the course of looking for the problem, we tried a Nait amp and also a NAP500 amp.
Strangely both the cheaper and more expensive amplifiers did not have the same problem with bass notes. My point being that, IMHO, one can not consider the speakers without considering the amplifier.
That's an easy one. We have all chosen our projects from that which 'fits' our own guiding criteria. Me, I wanted a Class A amp and NP designs them, hence I chose an Aleph.
This was written in rush, I hope it makes sense.
Regards
Paul
AKSA said:
I tend to think that before we blame ourselves for not understanding those subtle effects, we need to confirm the very existence of those subtle effects.
The spin-misters of the high-end audio would very much like us to beleive that those subtle effects are there, and our brains and sweat and hardwork will also want us to believe that too. But are they really there? Did we really hear what we thought we heard?
there is no shortage of people, even here, claiming to be able to hear 0.0001% THD, or cable directionality, or other crazy things. Are they proven?
So far, I have not seen scientific (that will including listening tests) evidence in support of those claims.
SuppersReady said:
That's right. And that even adds more to the complexity, right?
SuppersReady said:
Yes, the idea makes sense, but is not the point. Some just don't have guiding criteria, and they don't even know what they want. If you like class A, you can choose Death Of Zen instead of an Aleph, can't you?
Though we may have different criteria, we hear music for exactly the same reason more or less. We want to enjoy the music, right? Not just running from one amp to another amp pretending that our "level" of satisfaction criteria getting higher.
To see how useless the "criteria" is, change your amp, you may detect the difference, but you may not be able to decide which one is better, only your "preference". Now add 0.47uF to the crossover of your lovely speaker. You may not be able to detect the difference, but I will guarantee that you will have horrible life after that, if you know what I mean
Pavel x 2, Jay,
No problem at all; I have no difficulty whatever in a wide variety of points of view and believe this technical conundrum will only yield its answers if debate - some of it perhaps even weird - is maintained. This is not a competition, and I will not reduce it to anything even related to it. I have the highest regard for the intellects of all persons involved in this quest, and just a few of my heroes are JLH, Jean Hiraga, Per Abrahamsson, Kevin O'Connor and Nelson Pass.
Neither am I particularly original in my thinking, but I'm a good listener and not afraid of technological convergence. I was watching Bill Clinton in interview last night, and he made a particularly telling comment about foreign affairs, and the issue of ego. He suggested that ego merely obscured the truth; the same is true in a smaller way here!
I think the scientific method has had good press for a couple of hundred years, but it's made little headway in international politics or religion. I believe that amplifiers do make a difference, I'm sure the Pavels agree with me there, but the real question is how we appraise, identify and remedy the acoustic issues implicit in amplifying musical waveforms. This can all be done scientifically, I'm sure of that, but to be successful a degree of subjectivity is required which is, at this time, not particularly fashionable. And it's even possible, just remotely, that we are measuring the wrong things............
Thanks guys, great debate,
Cheers,
Hugh
No problem at all; I have no difficulty whatever in a wide variety of points of view and believe this technical conundrum will only yield its answers if debate - some of it perhaps even weird - is maintained. This is not a competition, and I will not reduce it to anything even related to it. I have the highest regard for the intellects of all persons involved in this quest, and just a few of my heroes are JLH, Jean Hiraga, Per Abrahamsson, Kevin O'Connor and Nelson Pass.
Neither am I particularly original in my thinking, but I'm a good listener and not afraid of technological convergence. I was watching Bill Clinton in interview last night, and he made a particularly telling comment about foreign affairs, and the issue of ego. He suggested that ego merely obscured the truth; the same is true in a smaller way here!
I think the scientific method has had good press for a couple of hundred years, but it's made little headway in international politics or religion. I believe that amplifiers do make a difference, I'm sure the Pavels agree with me there, but the real question is how we appraise, identify and remedy the acoustic issues implicit in amplifying musical waveforms. This can all be done scientifically, I'm sure of that, but to be successful a degree of subjectivity is required which is, at this time, not particularly fashionable. And it's even possible, just remotely, that we are measuring the wrong things............
Thanks guys, great debate,
Cheers,
Hugh
Nicely put. Two or three years ago, I had an wonderfully satisfying afternoon playing Led Zep LPs through a decidedly low-fi pair of music centre speakers and a Kenwood pre-power system. Subjectivity is such a variable quantity, isn't it?
Or put it on the end of a PSU for a more beneficial result? Same cap, different result. Preference is useful in ensuring variety, otherwise we would all drive Fords.
Science and logic will take us only take us so far, it gives us the building blocks. Subjectivity and imagination takes us forward in many cases. It's just a shame it can be such a hit and miss approach. And with audio, quite expensive too!
Hi Hugh, I'm amateur too and I listener too, I'm not " measured only " madman. If is any problem observed, may be later explain , so I was asking for this. I don't like, when is something put forward to me like dogma, " here it is and don't ask me, for what it is ". Yes, fast diodes have better recovery time, so disturbing will be better. I mean, that amp must be made such to be immune agaist this disturbing. If is not, you may listen different sound. All is related to all, so it must not be saying as common problem - probably some amp have this problem and some other have not . As you know, amp is not only schematic, is very significant, how is designed PCB and how look all construction. I mean, that most of published deigns are not perfect, 'cos give to people too much space for theirs phantasy and so later you can to see questions about hum, noise ( 'cos it oscilate ), grouding etc. I don't know details of your constructions, but references are excelent, your directions is probably OK . Cheers. Pavel
, so I was asking for this. I don't like, when is something put forward to me like dogma, " here it is and don't ask me, for what it is ". Yes, fast diodes have better recovery time, so disturbing will be better. I mean, that amp must be made such to be immune agaist this disturbing. If is not, you may listen different sound. All is related to all, so it must not be saying as common problem - probably some amp have this problem and some other have not . As you know, amp is not only schematic, is very significant, how is designed PCB and how look all construction. I mean, that most of published deigns are not perfect, 'cos give to people too much space for theirs phantasy and so later you can to see questions about hum, noise ( 'cos it oscilate ), grouding etc. I don't know details of your constructions, but references are excelent, your directions is probably OK . Cheers. Pavel- Status
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