moamps said:
Hi,
I agree with you!
I'm listening to a various GC's for a few years now, and have tried many variations of it (different IC's, PS, inv/noninv, various gain settings etc.); my choice (soundwise) is noninv, high gain, TDA7294 with 2 schotky bridges + 4x1000uF. I also had opportunity to use PS Audio power regenerator (300VA w. multiwave option) and found that it adds sonic character of its own to every component that you plug in. It had the same effect on DAC, power amp and even CD transport. And while I mostly liked what it did to DAC or CD (softer, less grain, a bit warmer) it was just to soft and slow on poweramp. So -to my ears PS Audio Powerplant adds character of its own although it should just provide clean AC power, and it seems that it is so with just about every audio PS.
That's very similar to my findings. While my power regenerator works fine with DAC, I didn't really liked it with CD transport and it was simply not acceptable on a gainclone. It changed the amps caracter, by making it slow and blurred. That's why I have reservations regarding active PS. I also remember Mr.Pass saying, in second Zen article, that he tried both active and passive supply with Zen and passive sounded better.
Supplies and Demands
"I'm sure that sooner or later someone will try regulated supply and reports on comparison with a passive one. Because only then, I will believe it's better."
Many people have advocated regulated supplies and I have noticed improvements on several amps with the use good (not bench supply) regulators. I have outlined what I did on my LM1875 amp but there are many other possibilities for regulators.
If people are happy with unregulated supplies who am I to stand in the way? An unreglated supply with 1000uF caps as a lot of ripple voltage when the amp is actually driving speakers rather than just idling. Let your ears, curiosity and depth of your pockets be your guide.
Conduction angle is a factor in the nature of supply noise and reading about the PS audio multiwave approach is very interesting:
http://www.psaudio.com/articles/multiwave.asp
This is an issue in other line powered equipment than audio as well and power factor correction is a hot area and I believe is required by law for new products in the near future. Power factor correction is already pretty standard in switching power supply designs.
Peak currents in diodes are easily limited in supplies with a low value resistors in series with the transformer secondaries. Jocko has been a proponent of this idea for many years and I also have used this approach. Limiting peak diode currents with magnetic saturation of small transformers when using fairly large capacitors is not a good idea. Also as I remember, Hugh Dean thinks 10,000 uF to be about the limiting value for filter caps in Class AB amps. There are compromises with large value caps and you can have too much capacitance in a supply.
As an example of a pretty sophisticated unregulated supply, the following is quite interesting (Although I would put resistors in series with the snubber caps):
http://www.ub-elektronik.de/download/ntke.pdf
I can only hope that person accusing me of being stingy with ideas was kidding........ many on the forum have come out in favor of me offering much less advice and opinions!
"I would be willing to say that Fred probably likes the IXYS diodes."
That's funny so would he........ I am glad someone will do a little digging aroung here. And speaking of digging, I am off to watch the first season of "Six Feet Under" on DVD. The first three episodes were very very strange.
"I'm sure that sooner or later someone will try regulated supply and reports on comparison with a passive one. Because only then, I will believe it's better."
Many people have advocated regulated supplies and I have noticed improvements on several amps with the use good (not bench supply) regulators. I have outlined what I did on my LM1875 amp but there are many other possibilities for regulators.
If people are happy with unregulated supplies who am I to stand in the way? An unreglated supply with 1000uF caps as a lot of ripple voltage when the amp is actually driving speakers rather than just idling. Let your ears, curiosity and depth of your pockets be your guide.
Conduction angle is a factor in the nature of supply noise and reading about the PS audio multiwave approach is very interesting:
http://www.psaudio.com/articles/multiwave.asp
This is an issue in other line powered equipment than audio as well and power factor correction is a hot area and I believe is required by law for new products in the near future. Power factor correction is already pretty standard in switching power supply designs.
Peak currents in diodes are easily limited in supplies with a low value resistors in series with the transformer secondaries. Jocko has been a proponent of this idea for many years and I also have used this approach. Limiting peak diode currents with magnetic saturation of small transformers when using fairly large capacitors is not a good idea. Also as I remember, Hugh Dean thinks 10,000 uF to be about the limiting value for filter caps in Class AB amps. There are compromises with large value caps and you can have too much capacitance in a supply.
As an example of a pretty sophisticated unregulated supply, the following is quite interesting (Although I would put resistors in series with the snubber caps):
http://www.ub-elektronik.de/download/ntke.pdf
I can only hope that person accusing me of being stingy with ideas was kidding........ many on the forum have come out in favor of me offering much less advice and opinions!
"I would be willing to say that Fred probably likes the IXYS diodes."
That's funny so would he........ I am glad someone will do a little digging aroung here. And speaking of digging, I am off to watch the first season of "Six Feet Under" on DVD. The first three episodes were very very strange.
Attachments
Fred
LOL, it wasn't an accusation but a directive. I too had read your opinion on the IXYS diodes but I wanted to make sure that this opinion carried over to the gainclones. You will note that Peter changed his opinion from 1520's to 820's so it wasn't unreasonable to assume that you could have had a change of opinion. Alot of these part selection questions don't fall into cut and dry formulas (at least they don't to me). I guess you would concede that diodes appropriate for an Aleph-X would not necessarily be appropriate for the Gainclones.
Peter
regarding the MUR820 from IR, would you be interested in a swap so we can compare? Also, I am assuming that Fred was talking about the GA diodes from IXYS and they only go up to a 17A rating. How do you think these IXYS diodes would hold up in a 20A biased stereo Aleph-X (16Vx2.5A per FET)?
regarding the MUR820 from IR, would you be interested in a swap so we can compare? Also, I am assuming that Fred was talking about the GA diodes from IXYS and they only go up to a 17A rating. How do you think these IXYS diodes would hold up in a 20A biased stereo Aleph-X (16Vx2.5A per FET)?
I didn't like IR diodes. I also have IXYS bridges I will use in my Alephs. 20A might be a bit fragile in Alephs with regards to inrush currents. But you might try. I got today some On Semi MUR 860 and they almost sound the same as Motorola ones, evcept for more high frequencies, yet they are not as harsh sounding as IR diodes.
What are our more learned correspondents views on the theory that a ready-built rectifier bridge has the advantage of closer matched diodes as they are all built on the same silicon substrate?
The diodes in a bridge are also thermally coupled.
And have the various candidates for rectifier diodes, suggested in this thread, been tested with snubber capacitiors?
The diodes in a bridge are also thermally coupled.
And have the various candidates for rectifier diodes, suggested in this thread, been tested with snubber capacitiors?
Fred,
Maybe I was unclear, but I did not mean deliberately using a
low-rated transformer to increase the conduction angle; I fully
agree that a series resistors seems a more sensible way to
achieve that. Rather, I was curious whether the reason a
high-rated transformer can sound better may be correlated to
the conduction angle, that is, could it be that a big transormer
sounds better in those cases where the conduction angle is
small so a "normally-rated" transformer saturates from the
peak currents? If so, this would give us a somewhat better
understanding of transformer selection than the usual
rules-of-thumb.
The multiwave article was interesting. Actually, I first thought
it was a joke you posted to test us, but it seemed too elaborate
and after digging through all the marketing BS it was rather
clear what they are doing. Beware though, at least one of
the pictures is deliberately misleading, but only to a degree
in the usual marketing way. It may also be worth noting that
Mark Levinson uses a regeneration approach in their current
preamps, but as I understand it they only regenerate a single
sine wave at the aricraft standard frequency of 440 Hz (or is
it 400?, I can't remember). Their motivation for this is vague,
though, discussing the availability of components for aircraft
PSUs.
Maybe I was unclear, but I did not mean deliberately using a
low-rated transformer to increase the conduction angle; I fully
agree that a series resistors seems a more sensible way to
achieve that. Rather, I was curious whether the reason a
high-rated transformer can sound better may be correlated to
the conduction angle, that is, could it be that a big transormer
sounds better in those cases where the conduction angle is
small so a "normally-rated" transformer saturates from the
peak currents? If so, this would give us a somewhat better
understanding of transformer selection than the usual
rules-of-thumb.
The multiwave article was interesting. Actually, I first thought
it was a joke you posted to test us, but it seemed too elaborate
and after digging through all the marketing BS it was rather
clear what they are doing. Beware though, at least one of
the pictures is deliberately misleading, but only to a degree
in the usual marketing way. It may also be worth noting that
Mark Levinson uses a regeneration approach in their current
preamps, but as I understand it they only regenerate a single
sine wave at the aricraft standard frequency of 440 Hz (or is
it 400?, I can't remember). Their motivation for this is vague,
though, discussing the availability of components for aircraft
PSUs.
Re: motorola / onsemi diodes?
Peter:
I like them, but I have not tried the MURxxx. I was attracted for the MSRxxx since the data sheet specified "soft" vs. the datasheet for the MURxxx saying "ultrafast".
And no, I have yet done a datasheet comparison.
mlloyd1
Peter:
I like them, but I have not tried the MURxxx. I was attracted for the MSRxxx since the data sheet specified "soft" vs. the datasheet for the MURxxx saying "ultrafast".
And no, I have yet done a datasheet comparison.
mlloyd1
mlloyd1 said:
Peter Daniel said:
I have some Elna Cerafine 100uF / 25V ROA series. Can I use those somewhere in my gainclone? Like bypassing the 1000uF standard caps I use...?
http://www.elna-america.com/PDF/ROA.PDF
Voltage in my gc after bridges are 35 volt.
http://www.elna-america.com/PDF/ROA.PDF
Voltage in my gc after bridges are 35 volt.
This evening I had quite some fun again with my gainclone. I am still waiting for my 4.7 uF 50 V BG N's to arrive that I plan tol put on the bridges and use as input cap. So I tried some caps I had laying around here on the bridges. I connected them with crocodile clamps. I tried 2.2 uF WIMA MKS4 (bad) and 2.2 uF WIMA MKC4 (much better). WOW! This is really an improvement. The sound gets much more 'understandable', sort of cleaner and more warm&natural. Dynamics and bass is improved. Guitars are nicely rubber-like crispy. (difficult to put such things in words ). Too bad I only had one pair of MKC4's.I wonder what the BG's will do (especially when soldered without the 1 m leads I use now).
It's quite understandable it works. The PSRR is not so good for higher frequencies so some filtering is advisable. Though I had thought that the 1 uF cap I use across the + and - supply on the opamp did more...
Fedde
). Too bad I only had one pair of MKC4's.I wonder what the BG's will do (especially when soldered without the 1 m leads I use now). It's quite understandable it works. The PSRR is not so good for higher frequencies so some filtering is advisable. Though I had thought that the 1 uF cap I use across the + and - supply on the opamp did more...
Fedde
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