Amp6 Basic PSU cap question

[johnm]

Hi everyone.

I have an Amp6 Basic which I wish to improve by removing the single PSU capacitor which serves both channels (C1819) and instead use two Panasonic FC 2200uF/16v capacitors per channel connected directly to PSU pins 25 and 28, and 22 and 19 of the TA2020 chip. This should improve channel separation slightly from what I've read.

The only thing I am not sure about it the removal of C1819. Once removed is that it, or do I need to put a wire link between/joining the + and - holes where the capacitor used to be?

Many thanks.


- JohnM

[Lostcause]

Originally posted by johnm
Hi everyone.

I have an Amp6 Basic which I wish to improve by removing the single PSU capacitor which serves both channels (C1819) and instead use two Panasonic FC 2200uF/16v capacitors per channel connected directly to PSU pins 25 and 28, and 22 and 19 of the TA2020 chip. This should improve channel separation slightly from what I've read.

The only thing I am not sure about it the removal of C1819. Once removed is that it, or do I need to put a wire link between/joining the + and - holes where the capacitor used to be?

Many thanks.


- JohnM

Whatever you do....Don't bridge the two connections or you will be joining power directly to ground.
Otherwise, your idea is sound

[johnm]

Thanks for that!

So completely remove C1819 (or leave it there I guess for extra uF's!!) and then just solder the two PSU caps directly to the chip pins mentioned previously then?

Thanks,

- John

[Pano]

The pads and traces at C1819 tie the two power rails together. Of course, they are tied together back at the supply anyway.

Since you are hoping for more channel separation, I don't know what you'll get with the channels tied together at the pads of C1819.

Adding separate caps right at the pins should help, though. It would be no harm to leave C1819 in place. Just means more capacitance.

And NO, don't put a jumper in place of the cap. Short circuit!

[johnm]

Hi Michael!

Thanks for the advice - well went ahead and soldered the two 2200uF/16v caps to each channel (betwixt pins 19 and 22, and 25 and 28). Was a little tricky but got there in the end. Decided to leave C1819 in the end - the tracks lift off VERY easily on the 41Hz boards so I decided to not tempt fate here.

So far everything seems fine - already the sound seems a little more powerful and assured... but this could be psychosomatic as it's only just been on for 5 minutes I'll know for sure after a few hours listening. I'll also post some pictures.

Thanks for all your help everyone

- John

[Pano]

I'll bet it was tricky getting those caps in there!

Adding a caps right at the chip pins is the major mod that Vinnie R was doing in his Clari-T. And he was doing it on the SMD chip!


You should get the results you described, it's not your imagination.

[johnm]

Hi Michael!

Well been listing to the amp constantly for the past 5 hours and I have to report that - so far - i don't like the sound of the amp as much. The sound seems a little 'flat', dry and lifeless. The dynamic and 'natural' character of the Amp6 Basic seems to have taken a back seat. The sound is a little 'scratchy' as well (gotta love these descriptions!!!) - no sparkle. I'm hoping it's just a case of needing futher running in time, but at present music just isn't enjoyable or involving. In short it sounds like a bland transistor jobby from the 70s!

Is it possible to have too much capacitance with these amps? The original (single) cap in there is 1500uF. I've added an extra 2200uf per channel. I know the schematic from Tripath specifies a mere 180uF per channel!!! Perhaps I've over-egged the pudding here! If it doesn't improve within the next week I'll remove these two caps.

Any ideas/thoughts on this?

Cheers,

- John

[Lostcause]

Originally posted by johnm
Perhaps I've over-egged the pudding here!

I must admit that I prefer 2 x 1000uf's near/on the pins with about 2200uf off-board but it really depends on your listening levels (to me anyway). If you slam out the tunes then you need more capacitance in there,
I don't so it's best to keep the power in a reasonably small ... low ESR package...
just my £0.02p worth.....

[johnm]

...also depends on the sensitivity of the speakers as well. Mine are 89db so I never really noticed a problem with output levels before anyhow.

I think the Panasonic FCs are low ESR caps?

Like I said will give it a week and then revert back to the original spec - lesson learned

- J

[gmilitano]

Originally posted by johnm

Is it possible to have too much capacitance with these amps? The original (single) cap in there is 1500uF. I've added an extra 2200uf per channel. I know the schematic from Tripath specifies a mere 180uF per channel!!! Perhaps I've over-egged the pudding here! If it doesn't improve within the next week I'll remove these two caps.

Any ideas/thoughts on this?

John,

That is an interesting question. I've been playing around with the Amp6 (not basic). In particular, adding a stiffening cap to c1819. I added a 4900uF cap.

What I found is that with a small 4" fullrange driver (BD-Pipes) the stiffener cap resulted in slightly less bass and the bass seemed dry, a little like you described.

Logically, more capacitance would be expected to help the bass. However, I think that the stiffening capacitor adds more control of the speaker, so in the case of a small bass shy driver, you don't get any overshoot and the result is more accurate, but less bass. Has anyone else noticed this will small fullrange units?

Having said that, what sort of speakers are you listening using?

Cheers,
Gio.