When ever i have built power amps, ive always used large filter caps. How come the gainclone only has 1000uF per channel?
What happens if you use lots of uF's in a gainclone
What happens if you use lots of uF's in a gainclone
Didn't you just tick a little box to say that you had searched for an answer to this question? 😉
The Gainclone seems to break many long-held 'rules' of amplifier building. One example is with the amount of capacitance required in the power supply. It just doesn't need huge amounts of capacitance, in fact, adding it changes the sound.
Although a few people have said that they prefer more, most agree that sticking to the 1000uF per rail produces the best sound over all.
The Gainclone seems to break many long-held 'rules' of amplifier building. One example is with the amount of capacitance required in the power supply. It just doesn't need huge amounts of capacitance, in fact, adding it changes the sound.
Although a few people have said that they prefer more, most agree that sticking to the 1000uF per rail produces the best sound over all.
Hi Nuuk
If that is the case are discrete Amp designers using this idea?. Isnt the chip amp like a discrete amp built onto a chip? Has anyone come up with a theory why it should sound better without less uF's?
I have read quite a few of the thread relating to the GC. I dont remember any explaination about the filter caps except everyone using 1000uF caps.
BTW I did do a search but maybe i need to refine my words more.....
Ill have a go and build me a GC - and check out this quirk.....
If that is the case are discrete Amp designers using this idea?. Isnt the chip amp like a discrete amp built onto a chip? Has anyone come up with a theory why it should sound better without less uF's?
I have read quite a few of the thread relating to the GC. I dont remember any explaination about the filter caps except everyone using 1000uF caps.
BTW I did do a search but maybe i need to refine my words more.....
Ill have a go and build me a GC - and check out this quirk.....
I can think of no good technical reason why small total capacitance is better.
The power supply is a Voltage-source and as such should have low output impedance at all audio frequencies. This is particularly important for a power amp ic where voltage and current-gain stages share the same (undersized) PSU rails.
If degrading the PSU seems to improve sound then perhaps there are problems elsewhere with the design which are masked by using an inferior supply.
The power supply is a Voltage-source and as such should have low output impedance at all audio frequencies. This is particularly important for a power amp ic where voltage and current-gain stages share the same (undersized) PSU rails.
If degrading the PSU seems to improve sound then perhaps there are problems elsewhere with the design which are masked by using an inferior supply.
Mesh said:
Hi Mesh (your real name?)
If I may be as bold as quoting myself:
The use of such small reservoir caps may seem controversial, yet using higher values may well be lowering the time constant (slower) caused by the combined AC source impedance of the power transformer and rectifier bridge. The problem is that this is a complex dynamic inter-face as it is governed by both the charging cycles and interfered by the DC current requirement of the amplifier itself. I would love to see someone model this mathematically, could make for some interesting reading.
This is not exactly new thinking. I recall some fifteen years ago that Martin Colloms (of HFN & RR) writing on this very subject and he demonstrated to himself, as I recall it, how he could make sonic changes by varying the wire gauge between the Bridge and Reservoir caps. As far as using small caps in our Gainclones, I do know this, it has a great agility in the mid-bass that makes it as good as anything when playing acoustic or even electric bass, and other instruments that require good sense of pitch, pace and tonality.
This quote is taken from:
http://members.ozemail.com.au/~lisaras/gainclonesound.htm
Check it out, it has quite a few serious measurements that you will find interesting, including what happens when the 1000uF runs out of steam. The article is sub-titled: Gazing into the Dark.
Keep this in mind, the Gainclone chip has an awesome 120dB PSRR (typically).
Ah... you live in Maroubra? I used to live, at various times, in Kingsford, Matraville and Hillsdale. Now I live at the end of the M5 where it finishes just beyond liverpool. Get onto General Holmes Drive and I'm only 20 minutes away. If you want to get an idea what one of these little beasties sound like... hey, I'm no different from a lot of other audiophiles... I love to show my stuff off.
🙂
Regards
Joe R.
Joe Rasmussen said:
Why would anyone want to promote the interaction of PSU ripple and amplifier audio output by using an inferior supply?
Something wrong somewhere.
I for one use 15 000 uf per rail in my p/s for the lm3886 amplifier that I built. The p/s is remotely located so I follwed basic design principles and placed 1000 uf/ .01 uf caps directly by the chip.
DIRT®
DIRT®
Mesh said:
1 - The data sheet of some of these chips shows small supply caps;
2 - After the first builder reports that it sounds great, everyone will use it from that point onwards, because they ALL want it to sound great. Nothing unusual here.
(Except Joe Dirt. There's always people who spoil it and start to think for themselves...😉 )
Jan Didden
The problem I have with that is that the data sheets are aimed at low end applications - not esoteric HIFI. I dont think National would ever recommend 30000 uF for a chip amp. I also dont think they would be suggesting 300 VA or 400VA per channel! for a 30 watt amp running class AB.
I always thought that the ultimate power supply for an amplifier would be a battery ( apart from the obvious problem of producing 30V-0-30V at several amps) . Is this not true for a gainclone?
Hi mesh
Go a head and build your GC with the big power supply. In would go for regulated supplies myself.
I am convinced that a large number of folks out there in audioland like the sound of a soft power supply. Thats what they have listerned to all of there lives. Thats how they think electronic sound reproduction should sound. Hey, thats OK. If thats what you like more power to ya. Oh, you need the big power supply for that LOL.
later BZ
Go a head and build your GC with the big power supply. In would go for regulated supplies myself.
I am convinced that a large number of folks out there in audioland like the sound of a soft power supply. Thats what they have listerned to all of there lives. Thats how they think electronic sound reproduction should sound. Hey, thats OK. If thats what you like more power to ya. Oh, you need the big power supply for that LOL.
later BZ
janneman said:
on the same token, I don't recall national suggesting dual / mono transformers, fast recovery diodes, diamond heatpads and Egyptian maple casing either, 🙂.
The chip was probably designed for low-end applications and it wouldn't help its cause had National suggested all those "hi-end" stuff.
Plus, it just may not benefit from lots of high-end stuff.
my gainclone is running off about 9900uf per rail at the PS. Putting 3300uf per rail on the chip doesn't improve nor deteriate sound either - to my half deaf ears anyway.
Joe Rasmussen said:
yeah. And it goes downhill from there: 60db at 10k, and 20db at 1mhz for -psrr.
Exactly right. Even amps with high PSRR benefit from well regulated PSUs. High PSRR is does not mean that the PSU doesn't matter.
A DC voltage power supply does just that. Perhaps those who run there amps form batteries could improve the sound by putting resistors in the supply rails and injecting a bit of load depended 50Hz... Nice
A DC voltage power supply does just that. Perhaps those who run there amps form batteries could improve the sound by putting resistors in the supply rails and injecting a bit of load depended 50Hz... Nice
Some possible technical reasons:
1/ i'd expect the biggest would be the HF spurii (sp?) that any cap input power supply produces... the bigger the caps the higher the frequency of the grunge (and with the same energy packed into a smaller time-frame, a taller spike). As Millwood points out the PSRR of he chips falls as frequency goes up, so lower frequency/smaller caps is good.
2/ the impedance of a smaller cap is typically smaller making the supply lower impedance (this could be negated by using lots of small caps)
dave
1/ i'd expect the biggest would be the HF spurii (sp?) that any cap input power supply produces... the bigger the caps the higher the frequency of the grunge (and with the same energy packed into a smaller time-frame, a taller spike). As Millwood points out the PSRR of he chips falls as frequency goes up, so lower frequency/smaller caps is good.
2/ the impedance of a smaller cap is typically smaller making the supply lower impedance (this could be negated by using lots of small caps)
dave
Here we go again! Another drawn out debate over something that is surely subjective.
It is so easy (and reasonably cheap to build one of these Gainclones that it could be done in less time than it takes to read threads like this.
So the answer is build one - with a standard supply, a regulated supply, with two or even four transformers, one, two or four bridges, with small caps, huge caps or with batteries.
When somebody has built the lot, they can post on a thread like this with some authority. Otherwise we are just going over the same ground yet again; and I'm trying to avoid ruts!
It is so easy (and reasonably cheap to build one of these Gainclones that it could be done in less time than it takes to read threads like this.
So the answer is build one - with a standard supply, a regulated supply, with two or even four transformers, one, two or four bridges, with small caps, huge caps or with batteries.
When somebody has built the lot, they can post on a thread like this with some authority. Otherwise we are just going over the same ground yet again; and I'm trying to avoid ruts!
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