2 PSU caps in paralle vs 1 cap of the same total value?

[12AX7]

I don't think theres any difference, but i want to be sure before i take a awkwardly mounted (read: hard to remove) PSU cap board off to replace the 22uf with a 47uf. I like the higher filtering on the V1 node, so i want to double it. But rather than remove the board i can easily parallel another 22uf cap. Any reason to go to the trouble of getting a 47uf and replacing the 22uf rather than simply paralleling a spare 22uf i have?

[sluckey]

2 X 22 = 47. Well, close enough.

[12AX7]

Yes, that i know. What i was asking tho if there would be any difference in any way that would make getting a 47uf the better choice instead of paralleling a cap to get it.

[sluckey]

If you do the 22 you'll have some beer money left over.

[kagliostro]

In an italian forum were I'm member there is a very experienced guy (in electronics, not in tube amps) that say that to put capacitors in parallel isn't a good thing (but I don't know the reason for that and he didn't explain the reason)

As far as I can know many people uses paralleled electrolytic capacitors without any problem, more I've often read that HiFi guy do that and parallel more capacitors as to improve the efficiency of the filters in audio circuits

Instead of use one single capacitor they use more than one, as an example instead of a unique 60uF they use 3 capacitors 33uF + 20uF + 10uF

Also I've seen commercial guitar amps (one is Vox AC30CC2) that uses a small poly capacitor in parallel with the electrolytic capacitor on the RC filters, this is because of the different frequencies that can be shorted to ground by an electrolytic and by a poly capacitor, about this, if I remember well, also Merlin say something in his book

K

[archaos]

Any reason to go to the trouble of getting a 47uf and replacing the 22uf rather than simply paralleling a spare 22uf i have?

No, still it'd be preferable to have a spare of 100µF in series rated @ half the actual voltage (assuming your 22µF are rated in the 450-500VDC range, you'd need 100µFs rated @ 250VDC) if you wish a smaller footprint (especially concerning the Vishay TVA series).

that uses a small poly capacitor in parallel with the electrolytic capacitor on the RC filters, this is because of the different frequencies that can be shorted to ground by an electrolytic and by a poly capacitor, about this, if I remember well, also Merlin say something in his book

+1
A 100nF poly would indeed do the trick to eradicate parasitic noises.

[Fresh_Start]

IIRC Kevin O'Connor claims that there's a benefit in terms of ripple reduction with multiple caps in parallel, particularly for the reservoir cap.  Don't remember the details but it had to do with current flow.

Cheaper to piggy back the second 22uf.

What are you trying to accomplish?  Stiffer response?  Won't matter with a preamp triode (or two) because the current draw is so small.  Better filtering?  I'd work on the power supply closer to the rectifier.

Hope that's helpful,

Chip

[12AX7]

What are you trying to accomplish?  Stiffer response?  Won't matter with a preamp triode (or two) because the current draw is so small.

It actually does make a difference, and a very noticeable difference at that. But mainly it's a feel thing, and i'm not sure yet that i like it better like that so i'm not sure i'm even going to do this permanently.

[tubeswell]

22uF(450V)||22uF(450V) = 44uF(450V)

but in series

22uF(450V) + 22uF(450V)  = 11uF(900V)

so if you want a higher voltage rating put the caps in series and if you want the same capacitance overall, then each cap has to be double the capacitance. Is that what you were asking about?

[12AX7]

22uF(450V)||22uF(450V) = 44uF(450V)

but in series

22uF(450V) + 22uF(450V)  = 11uF(900V)

so if you want a higher voltage rating put the caps in series and if you want the same capacitance overall, then each cap has to be double the capacitance. Is that what you were asking about?

No. I know all the technical stuff like that. I was just asking if i want about double the capacitance i have now whether there is any benefit or drawback to paralleling vs one cap of the same value. But i think I'm going to pass anyways because i'm starting to think I prefer the looser feeling lower value at V1. But I may still do it because i'm thinking of a in between value. If i parallel a 10uf I'd be in the middle with 32uf. That might just give me the best of both worlds.

But that brings me to yet another question. If you parallel 2 caps and one is 500v, can you get away with less voltage on the other one ?(lets say 160v) How does the math on that work?

[sluckey]

If you parallel 2 caps and one is 500v, can you get away with less voltage on the other one ?(lets say 160v) How does the math on that work?

No. Parallel caps will have the same voltage across each cap, so each cap must be rated to withstand that voltage.

[12AX7]

Thanks