Whats wrong with large filter caps for Gainclone?

[Mesh]

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

[Nuuk]

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.

[arthur]

how about for chip amps in parallel

[Mesh]

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.....

[Richard C]

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.

[Cobra2]

I tried a Bridge/paralell, and found it needing 1000uF (x2) for each chip.

Arne K

[Joe Rasmussen]

Originally posted by Mesh
[B
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..... [/B]

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/~lisar...clonesound.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.

[Richard C]

Originally posted by Joe Rasmussen


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

Why would anyone want to promote the interaction of PSU ripple and amplifier audio output by using an inferior supply?

Something wrong somewhere.

[JOE DIRT®]

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®

[janneman]

Originally posted by Mesh
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.....

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