Choice of Power Supply Caps

[kptseng]

Hi All,

Need some help here.

I'm trying to do a recap of my integrated amp.
The original ones were supposed to be custom made by BHC Aerovox 63v 4,700uF. Size 22X40.
Using 50v should be ok too. And max size to use is 25X50.

Due to space constrain and availibility locally, I am thinking of changing to either:
BC Component 56 Series - 4,700uF 50v Size 25X40 or;
Aerovox ALP22 Series - 3,300uF 63v Size 25X45.

The specs are;
Choice - ESR(mohm) - Ripple - Impedance
BC Component 56: 58 - 3.18 - 51
Aerovox ALP22: 65 - 2.89 - 52

Looks like the Aerovox is better but will there be any problem if I now use 3,300uF instead of 4,700uF?

Thanks in advance.

[VEC7OR]

BC's are better than Aerovox by specs.

[kptseng]

Sorry, my mistake shoudl be the other way around

This is the correct one:

Choice - ESR(mohm) - Ripple - Impedance
Aerovox ALP22: 58 - 3.18 - 51
BC Component 56: 65 - 2.89 - 52

[AndrewT]

Hi,
if you could get Aerovox 50V 4700uF in your size then the spec should be even better.

Going down from 4m7F to 3m3F may affect the bass and lower frequency transients.

You may also encounter a shade of motorboating if the stack up of tolerances was against you but this is less likely.

Personally I would try hard to find 4m7F Aerovox or better.

[kptseng]

[Hi Andrew,

My main restriction is the size, diametre must be within 25mm.
The 4,700uF Aerovox has a diametre of 30mm so no can do......

I'll probably go for the safer bet and do the BC Component at 4,700 then.

Thanks.

[lndm]

A study of capacitors in AudioXpress (sorry can't remember which edition but results are partially on their site), found that 3300uF generally sounded better than 4700uF. This was due to the resonant effects of an electyolytic capacitor's inductance. It was not conclusive but a good generalisation.

3300uF should perform satisfactorily, there really isn't a huge difference.

[kptseng]

Hi lndm,

Thanks for that and I guess I'll try both.
Cheers.

[gp4Jesus]

Try both at the same time. Just leave the lid off temporarily.

When driving your amp hard, extra PS capacitance could help, especially in the bass if your transformer* and rectifier* are up to it.

Otherwise* stick close to stock spec parts.

Interesting reading on power supplies
http://www.tnt-audio.com/clinica/ssps1_e.html
http://www.tnt-audio.com/clinica/ssps2_e.html
http://www.tnt-audio.com/clinica/ssps3_e.html

cheers

Tony