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Two different values of electrolytics in PIMETA?

post #1 of 20
Thread Starter 
I'm building a PIMETA, and am planning on using two 1000uf 25v Black Gates for the filter caps. On the Tangent board, there are four spots for filter caps in a row, and given the size of the Black Gates, I can only populate the two outer spots.

My question is, is it ok to populate the middle two spots with a smaller cap? I have some 220uf Elna Cerafines laying around that I'd like to slap in those middle spots if I could. So there'd be a +/- pair of big BGs and a +/- pair of smaller Cerafines.

Would that work?
post #2 of 20
My guess is that'll work great. I believe Tangent once said he built a PIMETA with only one cap and it worked fine. Generally speaking, you'd like to get the total capacitance to be in the same ballpark. Most of the time, multiple caps are used because even though the bigger ones support more power (bass notes), they aren't as fast as smaller ones (dynamics and detail). However, something like a nice Black Gate is probably faster than much smaller regular caps, anyway.
post #3 of 20
What is the point of paying the premium for the Black Gates and then installing lesser caps in the other two spots?
I could almost understand if the whole "more is better" routine is better but in this case it isn't.
post #4 of 20
And this is DIY. Bend the legs, solder under the board, wire them externally... use your imagination. All BGs will fit.
post #5 of 20
One could also argue that 2000uF of capacitance in a PIMETA is already plenty and that just because there are 4 spots doesn't mean you have to fill them all.
post #6 of 20
2000 is way overkill already as it is... I regret trying out the ones you used because I had to bend them almost to the limit. The leads on both are loose now and they are sitting pretty high up, not to mention they look ugly and totally add space to the sides and top so you need a big case. Look..

lol.
( '-')
post #7 of 20
Quote:
Originally Posted by hYdrociTy View Post
2000 is way overkill already as it is... I regret trying out the ones you used because I had to bend them almost to the limit. The leads on both are loose now and they are sitting pretty high up, not to mention they look ugly and totally add space to the sides and top so you need a big case. Look..

lol.
( '-')
No offense, but there are ways of handling that correctly so that it doesn't quite present the problem that your photo shows. If the amplifier case size isn't an issue, the leads may be bent so that the caps are out horizontal and 90 deg. to the board. In the same way, the leads can be creatively bent so that the caps are horizontal and at the side - perhaps staggered if need be. A cable tie and some sort of standoff or glued on cable tie guide can help to stabilize things. As Yen's post indicates, there are a number of ways to make this work.

Just to be clear, though, I was agreeing that the 2 - 1000uF BG's should work well because of their quality, not that the Elna's should be stuffed in there, too.
post #8 of 20
Yea I'm actually going to transfer it to a hammond i have laying around, and that is as far as the caps can be bent to still fit in the case... Pity, as I should have chosen four bg's of smaller values. Guess I overestimated the free space in the enclosures..

Was there any particular beneficial reason the op might want to populate all four slots? maybe four 470 bg's would be faster than two 1000? it would certainly cost more...
post #9 of 20
Quote:
Originally Posted by hYdrociTy View Post
Was there any particular beneficial reason the op might want to populate all four slots? maybe four 470 bg's would be faster than two 1000? it would certainly cost more...
ESR should be lower.
post #10 of 20
I am putting 4x 270uF Nichicon PW in mine. I with I would have went with more now though. However, 2000 seems like too much to me. Theoretically you could but I wouldn't see where there would be much (if any) imporvement.
post #11 of 20
Quote:
Originally Posted by tomb View Post
Tangent once said he built a PIMETA with only one cap and it worked fine.
Actually, that was a PPA. The caps in the PIMETA are arranged differently, so it does need at least 2.
post #12 of 20
Mistake noted, but a single cap in a PPA is even more incredible. Thanks.
post #13 of 20
Quote:
Originally Posted by slowpogo View Post
I'm building a PIMETA, and am planning on using two 1000uf 25v Black Gates for the filter caps. On the Tangent board, there are four spots for filter caps in a row, and given the size of the Black Gates, I can only populate the two outer spots.
To me, use Black Gate here is (at least little bit) wastful...
post #14 of 20
Thread Starter 
Quote:
Originally Posted by applegd View Post
To me, use Black Gate here is (at least little bit) wastful...
Not to argue with you, but why? The PIMETA seems like a sophisticated enough circuit to bring out the quality in Black Gates, at least compared to cheap Nichicons or something... maybe the high-grade FK or N series would be wasteful.
post #15 of 20
Quote:
maybe the high-grade FK or N series would be wasteful.
Not at all.
(the difference is not as dramatic in a Pimeta as it is a PPA2 but it is still noticeable)
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