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Old 17th February 2014, 09:56 PM   #21
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Quote:
Originally Posted by Destroyer OS. View Post
You don't see the value in quicker response to changes in demand for power? K... These aren't constant current supplies.
All else being equal, a larger capacitance has a slower MINIMUM "speed" than a small capacitance. Not a slower MAXIMUM "speed".

ESL and ESR can be unequal, but paralleling small caps with large ones solves this,
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Old 18th February 2014, 03:39 AM   #22
godfrey is offline godfrey  South Africa
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Quote:
Originally Posted by Destroyer OS. View Post
You don't see the value in quicker response to changes in demand for power?
Smaller caps do respond quicker.
Unfortunately, they respond to high power demands by collapsing the supply voltage. OTOH, they recover faster too, so the full supply voltage is restored very quickly when you don't need it.
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Old 18th February 2014, 04:37 AM   #23
godfrey is offline godfrey  South Africa
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Originally Posted by 00940 View Post
Interestingly, the discrete amps' crowd never took interest in those undersized PS.
Well, obviously. That's because discrete designers need to know something about electronics, otherwise they wouldn't be able to design discrete circuitry.

In contrast, a lot of chipamp "designers" chose to go the chipamp route in the first place precicely because they don't know much (if anything) about electronics. They just copy the simplest circuit they can find in the app-note (or on the internet, for those who wouldn't recognize an app-note if it slapped them in the face). Then they put all their "design" effort into making the box look pretty (and choosing what color capacitors to use, of course).

Fortunately for those with commercial aspirations, this plays right into the hands of certain magazine reviewers who judge audio products strictly by sound quality, and base their evaluation of sound quality strictly on look&feel and price (Don't be a dumbass and try to sell an LP demagnetiser for $35.00 - Everybody knows a decent demagnetiser costs at least a couple thousand bucks).

Unfortunately, gullibility tends to be proportional to ignorance, so most of them will have swallowed the "capacitance is bad" kool-aid even before they built their first chipamp, and this gets reflected in their "designs".
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Old 18th February 2014, 06:14 PM   #24
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I was following JoeryTech his build because his use of materials (which looks good).

I also have a LM4780 (dual mono) (Audiosector) which sounds fine!!!!, but after a while I found out that my setup had a "lack" of bass. Reading JT his experience it seemed that he does not seem to have a "lack of " bass. To my surprise the thread went off topic due to the bass question. And JT started this thread. There are many replies but none of them gives “THE” answer. I do understand that “THE” answer is hard to give.

But what to do?

Well first of all I think that Peter Daniel brings us a perfect kit so I first checked the rest of my setup.

At the source-end of my setup there was progress to be made. My Musical Fidelity V-Dac II and my Musical Fidelity V-LPS II were in need of a better power supply. So I build a new PS for these devices. The new PS (still on a bit of wood) made a HUGE!! difference and I wished that I had done this upgrade a bit earlier.

But still my other diy amp (Arjen Helder TA2020 MKIII) seem to give a better bass with this new.. source, but in the highs and mids the LM4780 won at this point.

But what about the bass and capacitance?

Reading many threads these two seem to be linked. There seem to be pro’s and con’s about adding caps. My skills on this DIY are a bit poor so some off the replies are a bit difficult to understand and I don’t have a pile of parts laying around to test different setups. But than it came to me , I have a snubberized PS on my LM3886 from Chipamp.com with 2x 10.000uf , which is a bit offline at the moment.

I got my soldering iron out and put these snubberized PS units in my LM4780.

The result?

It is hard to tell if the “high’s” and the “mid’s” had any benefit of this change but what I can say that the bass in “this” setup increased dramatically. Is 10.000uf (one cap, with snubber) at each rail the answer? Well I am pleased so far, so I am going to build a new PS for the LM4780 and add the possibility to use large caps or many small caps.

I realize that this is not “THE” answer but yet another opinion or/and possibility which I am happy with.
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Old 18th February 2014, 06:21 PM   #25
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Well in the meanwhile PD gave a reply on the building instructions thread which will be the other test. Using Bi-amp for my setup.

Isn't DiY audio fun? all these different solutions?
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Old 19th February 2014, 03:30 PM   #26
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Quote:
Originally Posted by mrWagner View Post
Ideally there should be infinite capacity for the amp, so it gets the same voltage always. If it is not infinite, as the 50/60Hz goes, 90% of the time the chip gets the juice only from the capacitor and not from the transformer. And I guess this explains why bigger is better. Don't really understand why there is an argument at all.
I agree with you. THAT is the purpose of an smoothing capacitor. To store energy for a brief period of time while the sinuoidal signal from the mains passes through the X axis, thus providing 0 volts and 0 current. So to avoid the supply voltage to drop to 0, you put capacitance there. But capacitors are finite in their capabilities, so their energy gets "exahusted" and they reflect that by suplying a lower voltage as time goes by. Then when the sinuoidal cycle start going up from 0 volts, as soon as that voltage is above the one from the capacitors, they get charged.

So in an unregulated PSU you get what is called ripple, nothing more than the variation of that supply voltage. It is supposed to be constant, but it isn't. The more constant it is, the less the performance of the amplifier varies with time. Take the LM3886 datasheet and see all the parameters that are affected by the supply voltage. Now think they will be varying like 100 or 120 times per second. Not a good thing.

That's why the more capacitance, the better. With some 'but's.
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Old 19th February 2014, 03:41 PM   #27
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Originally Posted by mindutis View Post
Well some still listens to mono recordings
Anyway, 4700uF minimum. I like it 10mF or much more. If it is even more then soft start is needed.
What's your opinion on regulated PSU's for Gainclones? I used some LM338 on one of them. Have you heard one of them?



Quote:
Originally Posted by Destroyer OS. View Post
High capacitance is fine, but the average 10-15,000uf cap is garbage. Spend the $ to make it a very good, very fast capacitor or use multiple smaller values. This seems to escape everyone, always trying to find a compromise between enough capacitance for bass, and yet not destroy the highs.

Peter Daniels has used 100/1000uf and 1500/50uf for Chip/PSU. Blackgate N/Blackgate STD, Panasonic FC/Panasonic FC. In either situation the caps are small enough and responsive enough to provide good quality music, bass maybe respective of speaker load however. But a lot of people on here are aware that 10-15,000uf has some serious merit, per channel.

What would I try? Hm, well I'd try a few things perhaps. But I think the approach PD took was legit. However I'd probably use Elna SIlmic II's or Nichicon FG's to play around with these days.

I wouldn't be doing any mythical bypass caps of small value (film caps or whatever) that are just ringers.
How do you measure how "fast" is a capacitor? By its ESR?

And yes, as you said, those caps are small enough to provide some quality music. But I don't think diyers strive for "enough". It isn't enough, at least for me.

You talk about "mythical" bypass capacitors, so you are implying that bypassing isn't an extended industrial and professional practice and its only merit is being used by some audio diyers?
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Old 19th February 2014, 05:31 PM   #28
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There isn't a measurement for speed. It's done independantly by people that either make faster capacitors, or need them in their equipment. For use lamers we can just use ears and principles. I know, it sucks...

I use multiple small capacitors. While one could let the voltage sag greatly, creating large ripple current, one can also use enough capacitance that it's very negligable. PD figured out very good balances, which eliminate other problems discussed that can come up with a need for snubber. He said snubbers don't sound right.

Search for bypass capacitors. There's some big threads on how they're basically total BS in most situations.
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Old 19th February 2014, 06:48 PM   #29
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Originally Posted by regiregi22 View Post
I agree with you. THAT is the purpose of an smoothing capacitor. To store energy for a brief period of time while the sinuoidal signal from the mains passes through the X axis, thus providing 0 volts and 0 current. So to avoid the supply voltage to drop to 0, you put capacitance there. But capacitors are finite in their capabilities, so their energy gets "exahusted" and they reflect that by suplying a lower voltage as time goes by. Then when the sinuoidal cycle start going up from 0 volts, as soon as that voltage is above the one from the capacitors, they get charged.

So in an unregulated PSU you get what is called ripple, nothing more than the variation of that supply voltage. It is supposed to be constant, but it isn't. The more constant it is, the less the performance of the amplifier varies with time. Take the LM3886 datasheet and see all the parameters that are affected by the supply voltage. Now think they will be varying like 100 or 120 times per second. Not a good thing.

That's why the more capacitance, the better. With some 'but's.
I have read the following article:
http://www.tnt-audio.com/clinica/ssps2_e.html

And I quote from that:

"Capacitors

As noted before, electrolytic capacitors serve two functions - to filter out the rectified supposedly DC voltage and to act as energy storage for those peaks which may require very large currents. Hence, they also stabilize the voltage by acting as energy reservoirs which offload the transformer, but this function is not of prime importance (however, it is far from being unimportant). I have set the priority list here: 1) filtering and 2) energy reserves.
In practice, manufacturers tend to use them as a panacea or cure-all for all other in-built power supply shortcomings. There is no doubt that filter capacitors have crucial influence on the sound obtained - that much is agreed upon by all, no matter what school they belong to. Therefore, they require special consideration."


It sounds like this guy have a point.




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Old 20th February 2014, 08:31 AM   #30
AndrewT is online now AndrewT  Scotland
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Quote:
Originally Posted by regiregi22 View Post
.........How do you measure how "fast" is a capacitor? By its ESR?..........
No.
The ESL tells you how it reacts to changes in current demand.
Then you MUST add on the inductance of the connections and cables and traces from the supply to the device that changes the current.

The connection length dominates the total inductance.

That's where small capacitors can show an improvement. They can be placed close to, or in, the circuit that changes it's current demand.
Big caps must by size be located outside the circuit.

It is for those reasons that properly designed decoupling is in at least two stages.
Stage 1 is the HF decoupling located right at the point of changing current demand. Tiny X7R are the only size that gets right inside the circuit.
Stage 2 is the MF decoupling and is usually smallish electrolytic located a bit farther away, maybe 20mm to 40mm, or so.

Generally smoothing capacitance is at the transformer. This can never operate as decoupling. It is simply too far away.

Omitting the smoothing capacitance at the transformer forces the designer to bring the charging pulses to the capacitors at the amplifier.

No one will ever convince me that bringing those charging pulses to the amplifier is good for sound quality. Think about it!
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