Hello guys!. Well I have seen some "Gainclones" and some of them use 'BIG" capacitors in the power supply I used 10 mf 50v (LM3875).and 1000mf 50v in the boards that have the LM3875(I do not know how you call that board).I saw this board in Audio-sector "Peter Daniel",and they use 4.7mf 50v in the power supply. my questions are:
a) What is the difference between the ones using small caps and the ones using big caps in the power supply?.
b) is it important the quality of the 10mf 50v in the power supply?
c) since I have "Black Gates" 1000mf 50v in the boards with the LM3875,should I use "Black Gate" 10mf 50v or 4.7mf 50v in the power supply too?.
thank you guys!
a) What is the difference between the ones using small caps and the ones using big caps in the power supply?.
b) is it important the quality of the 10mf 50v in the power supply?
c) since I have "Black Gates" 1000mf 50v in the boards with the LM3875,should I use "Black Gate" 10mf 50v or 4.7mf 50v in the power supply too?.
thank you guys!
lanchile07 said:
Small caps are OK if you want the amp to sound like a cheesy transistor radio that can't play low frequencies at any volume level without clipping.
Since you have Black Gate caps, I suspect you have already answered that question for yourself. I don't think it matters, and I wouldn't spend the extra money, but you'll find plenty of people who argue in favor of the more expensive caps.
See above.
I_F
Gainclone sounds like a Cheesy Radio?
"Small caps are OK if you want the amp to sound like a cheesy transistor radio that can't play low frequencies at any volume level without clipping"
So,are you saying that "Peter" Gainclones sound like a cheap radio?.
Because I got all the parts from Peter.there are many people here that have gotten these kits from Peter and they have the same configuration as mine.
Do you have or ever hear a Gainclone using these parts?
I asked you this question because ,I do not think you have!.
the sound is never like a " CHEESY RADIO".
"Small caps are OK if you want the amp to sound like a cheesy transistor radio that can't play low frequencies at any volume level without clipping"
So,are you saying that "Peter" Gainclones sound like a cheap radio?.
Because I got all the parts from Peter.there are many people here that have gotten these kits from Peter and they have the same configuration as mine.
Do you have or ever hear a Gainclone using these parts?
I asked you this question because ,I do not think you have!.
the sound is never like a " CHEESY RADIO".
In addition to I_Forgot's comments, here are some of mine.
The value of the capacitors you should use in an unregulated transformer based supply should be sized to provide the amplifier circuit with reasonably ripple free DC supply rails. Generally speaking, the smaller the cap the higher the supply ripple voltage, especially when more current is drawn from the supply. Don't forget that the size of the transformer is just as important as the size of the caps, since it charges the caps.
The quality of the caps closest to the supply pins of the chip is more important than bulk electrolytics directly after the rectifiers. Use good quality parts for the large value electrolytics and they'll be fine.
By "mF" you mean microfarad, which is more correctly abbreviated uF. Regardless, it won't hurt to use the small value caps in the supply, but they probably won't make much difference being in parallel with the much larger 1000uF on the boards.
lanchile07 said:
The value of the capacitors you should use in an unregulated transformer based supply should be sized to provide the amplifier circuit with reasonably ripple free DC supply rails. Generally speaking, the smaller the cap the higher the supply ripple voltage, especially when more current is drawn from the supply. Don't forget that the size of the transformer is just as important as the size of the caps, since it charges the caps.
The quality of the caps closest to the supply pins of the chip is more important than bulk electrolytics directly after the rectifiers. Use good quality parts for the large value electrolytics and they'll be fine.
By "mF" you mean microfarad, which is more correctly abbreviated uF. Regardless, it won't hurt to use the small value caps in the supply, but they probably won't make much difference being in parallel with the much larger 1000uF on the boards.
salas said:
Right you are! If you like an amp that can't play low frequencies loudly without distorting, by all means use a too-small transformer and too-small capacitors. You are free to choose!
In my dogmatic way, I prefer an amp that can reproduce the input signal with minimal distortion at whatever volume I choose to listen. If I want some change in the sound, I can add a tone control circuit. In my dogmatic philosophy, it is better to start with a good signal and add controlled, predictable amounts and types of distortion than to add unpredictable and uncontrollable distortion to the signal and hope that it comes out listenable.
Woof!
I_F
I_Forgot said:
These chip amps we talk about ain't no big canons. Not my cap of tea, I have put together a couple though, and the guys are right, they sound fresh with small designer PSU caps at least. With big ones they lose all character and sound bland. They don't meet several other criteria so they need their salt n' peppa so to speak.
Sometimes it's useful to carry an idea to extremes. Have you ever heard any audiophile say, "Darn, this sounds lousy because I made the power supply way too big and stable."? IMO, it's a problem if the power switch keeps burning up because of the startup surge. Or the bridge constantly fails. Or maybe it's a problem if the system plays for fifteen minutes on stored charge after turning it off!
OTOH, there's no question that too small a transformer and too little capacitance can reduce the power output and potentially degrade the sound due to ripple. So the $64 question is, where to stop? The common rules of power supply design like 1000uF per amp of output aren't too useful, since audio is a transient situation. One of the nicest sounding amps I have, about 50W/ch uses 8400uF on each side of the supply. Another similar one I "upgraded" to 19000uF per side, and it really didn't make much difference soundwise. IMO, 3000 to 10000uF per side is reasonable for 50W/ch amps, though I have nothing math-wise to back it up.
OTOH, there's no question that too small a transformer and too little capacitance can reduce the power output and potentially degrade the sound due to ripple. So the $64 question is, where to stop? The common rules of power supply design like 1000uF per amp of output aren't too useful, since audio is a transient situation. One of the nicest sounding amps I have, about 50W/ch uses 8400uF on each side of the supply. Another similar one I "upgraded" to 19000uF per side, and it really didn't make much difference soundwise. IMO, 3000 to 10000uF per side is reasonable for 50W/ch amps, though I have nothing math-wise to back it up.
In the case of Gainclones, yes, many times! This argument has been going on here for years now. The only useful answer is this: it depends on your speakers, and your taste. Start with 1000 uF on each pin (and the smaller caps on the PSU as supplied by Peter). Listen for a while and get used to the sound. Then insert say 10Ks between PSU and chip and listen again.
The point is you can ask this question and get many different answers. The Gainclone doesn't really work like a discrete amp where the 'bigger-is-better' PSU theory holds true! The only way to 'know' what is right for you is to try it yourself!
Hi,
very efficient high impedance speakers allow the chipamps to give of their best.
I believe Peter uses 96db speakers and produces a superb kit that performs very well.
Use 86db 8ohm speakers and you'll ask the the chipamp to deliver three times as much current for the same sound levels. Change to 4ohm low sensitivity speakers and the whole design/build philosophy changes yet again.
I think that the caps closest to the output stage have most influence on the sound quality. Those farthest away least effect.
very efficient high impedance speakers allow the chipamps to give of their best.
I believe Peter uses 96db speakers and produces a superb kit that performs very well.
Use 86db 8ohm speakers and you'll ask the the chipamp to deliver three times as much current for the same sound levels. Change to 4ohm low sensitivity speakers and the whole design/build philosophy changes yet again.
I think that the caps closest to the output stage have most influence on the sound quality. Those farthest away least effect.
Nuuk said:
While it may be true that the chips were designed using special quantum electromagnetic field cancellation and gravitational well anti-matter decoagulators, they are driving a speaker just like every "conventional" amp design, therefore, they need the same sort of power coming in to deliver the same sort of quality power out. The chips don't generate their own power (though an engineer friend of mine at National says the next generation will use the Casimir effect to extract zero point energy and power the chips without any external source!).
Garbage in = garbage out applies here.
I_F
I have no measurements to back it up, but I use 225VA transformer to power a stereo amp based on two LM3886TF, and it absolutely needs large caps (10000 uF/side) and good bypassing (100uF Pana FM at chip each rail).
I also have a PD LM4780 kit wired up in BPA (it was not created to work like that, TBH) with only 4700uF per side per chip + 1500 Fc at chip, mated to a 440VA transformer for each channel (880VA total), and it destroys the previous amp with my Dynaudio monitors (86dB/4 ohm), but submits to it on more benign loads (my mains are 90 db/w, 8 ohm)
The two amps are representatives of opposite ends of the PS design spectrum and have different characteristics, none of them are similar to the PD suggested scheme, or indeed even the one talked about by IF and Conrad. I would suggest experimenting and finding out for yourself.
Large transformer (VA>3x wattage), Large cap (4700-10000uf/side)
Medium transformer (VA>1.5x wattage), Large cap
Large transformer, small cap (1000-2200uF)
Medium transformer, small cap - This definitely is not to be tried, AFAIK
It will eventually depend on your speaker configuration. I see no need to be polarised as your taste is your own. IME the less the current demands placed on the chip, the freer you become to drop the reservoir capacitance and experiment. With the high PSRR of these chips, it may be possible to arrive at a sound you like at lower capacitance. I ran my BPA for a long time only on the default caps before sizing them up, first to 10000uF (which totally killed the sound) then back down to 4700uF. At that capacitance they delivered the right balance of sound for my mains.
I also have a PD LM4780 kit wired up in BPA (it was not created to work like that, TBH) with only 4700uF per side per chip + 1500 Fc at chip, mated to a 440VA transformer for each channel (880VA total), and it destroys the previous amp with my Dynaudio monitors (86dB/4 ohm), but submits to it on more benign loads (my mains are 90 db/w, 8 ohm)
The two amps are representatives of opposite ends of the PS design spectrum and have different characteristics, none of them are similar to the PD suggested scheme, or indeed even the one talked about by IF and Conrad. I would suggest experimenting and finding out for yourself.
Large transformer (VA>3x wattage), Large cap (4700-10000uf/side)
Medium transformer (VA>1.5x wattage), Large cap
Large transformer, small cap (1000-2200uF)
Medium transformer, small cap - This definitely is not to be tried, AFAIK
It will eventually depend on your speaker configuration. I see no need to be polarised as your taste is your own. IME the less the current demands placed on the chip, the freer you become to drop the reservoir capacitance and experiment. With the high PSRR of these chips, it may be possible to arrive at a sound you like at lower capacitance. I ran my BPA for a long time only on the default caps before sizing them up, first to 10000uF (which totally killed the sound) then back down to 4700uF. At that capacitance they delivered the right balance of sound for my mains.
Something I tried that worked very good for me is, obviously better quality large caps, like Nichicon Gold's. Then use a smaller bypass cap, like a Relcap RT for some, but not all of the chips. I bypassed the inner set and left the outer set alone. This gave me some nice transparency without tipping the amp up on the top end.
The "sound" of these bypass caps should also be similar to the sound of the larger caps, for consistent voicing.
Enjoy,
Bob
The "sound" of these bypass caps should also be similar to the sound of the larger caps, for consistent voicing.
Enjoy,
Bob
The consistent theme of this thread is 'see what works well for you'! There really isn't a hard and fast rule with chip amps. It's therefore wrong to say to newbies, do this or that! A big part of the fun of the chip amp is to tweak it to get the best sound from your speakers - as the good folks above have done!
Does the actual audio power output of a chipamp also taper off when using smaller caps?
I have noticed that the chipamp I am assembling doesn't really get warm, and that's with a large amount of signal going in. I have 1500uF smoothing capacitors and a smallish videocard heatsink.
Have any of you observed any relationship of chipamp heat output to powersupply capacitance? I'd imagine this should correlate to audio power output...
I have noticed that the chipamp I am assembling doesn't really get warm, and that's with a large amount of signal going in. I have 1500uF smoothing capacitors and a smallish videocard heatsink.
Have any of you observed any relationship of chipamp heat output to powersupply capacitance? I'd imagine this should correlate to audio power output...
No, none. All of 'em heat up similar (heatsinks at about 50 degrees C) to each other. Actually true for me across chips (4766, 4780, 3886) - but all run off the same supply voltage of 30VDC.
There may be a correlation with higher voltages as supply sag would be much higher with small-ish caps and regular loads, so one would notice a reduction in supply voltage, power output, and power dissipation. This may reuslt in lower temperatures on the heatsink - at least in theory.
There may be a correlation with higher voltages as supply sag would be much higher with small-ish caps and regular loads, so one would notice a reduction in supply voltage, power output, and power dissipation. This may reuslt in lower temperatures on the heatsink - at least in theory.
I was also worried about cap size before i built my amps
(see picture thread page 21)
I know this is a diyaudio thread so people are going to "overspend" on certain things that isn't the money worth for the added sound quality.
I used 4 x 10000uF caps per rail with my 500VA toroidal. Currently i am mostly useing it in stereo mode (until i build/buy my new other speakers)
I didn't opt for the expensive caps , mine are plain snap in ones , I think the manufacturer writing on it is REC or something.
I believe in a Stiff powersupply.
At each chip I have a 100uF cap.
And I love the sound compared to my previous amp.
(see picture thread page 21)
I know this is a diyaudio thread so people are going to "overspend" on certain things that isn't the money worth for the added sound quality.
I used 4 x 10000uF caps per rail with my 500VA toroidal. Currently i am mostly useing it in stereo mode (until i build/buy my new other speakers)
I didn't opt for the expensive caps , mine are plain snap in ones , I think the manufacturer writing on it is REC or something.
I believe in a Stiff powersupply.
At each chip I have a 100uF cap.
And I love the sound compared to my previous amp.
Isn't this whole thing about HF injected due to large load currents under a small conduction angle?
Big low impedance caps close to the chip will draw high currents with lots of HF garbage from the switching diodes and this could affect the chip. Move those big caps away from the chip and use small caps close to the chip (as recomended by the manufacturer) seems like a clever thing to do. Maybe look over the impedances and try to filter out some of the high frequency noise and spikes between the local and "remote" filter bank. Snubbers anyone?
Small caps and the ripple and sag of the suply that will be the result from it will starve the amp and reduce the max power you can squeeze out from it.
/Peter
Big low impedance caps close to the chip will draw high currents with lots of HF garbage from the switching diodes and this could affect the chip. Move those big caps away from the chip and use small caps close to the chip (as recomended by the manufacturer) seems like a clever thing to do. Maybe look over the impedances and try to filter out some of the high frequency noise and spikes between the local and "remote" filter bank. Snubbers anyone?
Small caps and the ripple and sag of the suply that will be the result from it will starve the amp and reduce the max power you can squeeze out from it.
/Peter
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