Power supply caps

I have upgraded the caps in my previos phono preamp. I had already upgraded the op amps, resistors, coupling caps and regulators. So I can definitively speak to the effect of just changing power supply caps.

In my case the backround got blacker as in the very low level detail was not lost or masked in the backround noise.

Also, the high frequencies lost an annoying zingyness. It was like I had changed from an agressive metal dome tweeter to a smoother silk dome type.

In my case the existing caps were very cheap and I replaced them with Blackgates.

I will also conceed that I may not have heard much of a difference if I had not already upgraded virtually everything else in the circuit.

Ofcourse, YMMV

I replaced power supply caps in Cambridge Audio A3i amp a while ago. Theoretically it should not make any difference since amp was only few years old (unless Canadian dealer sold me very old amp in new box) but it had pronounced effect on the bass. It became taut and more dynamic.

It depends on temperature of your amp and amount of time it was powered on. Every 10deg C cuts life of capacitor by factor of 2. Good capacitor can last in room condition for 50 years but there is always some temperature increase. Aging of electrolytic capacitors is simply drying out of electrolyte causing increase in ESR (effective series resistance) reducing damping effect amplifier has on speakers. Good replacement caps should have low inductance and low ESR. If old capacitors have wires soldered to them make note where. Load should be connected to last capacitor while rectifier should be connected to first one (opposite side of the bank). Soldering wires in wrong place is common mistake that might end up in audible hum.

Thanks guys. I have been slowly coming to the conclusion that literally everything matters, so I sort of figured that the PS caps would matter. I'll probably replace the PS caps before replacing the ones in the pre, since the ones in the pre aren't exposed to much heat. Then I will be able to tell for sure how much difference the PS caps make.

Don't forget to unplug and make sure capacitors are completely discharged before touching them.

Not all caps are equal in size either so do your homework and make sure they will fit.

I'm having trouble finding caps with the correct values. I need 4700uF 50VDC, 470uF 63VDC, and 1000uF 25VDC. Couldn't find them on Parts Connection, Parts Express, or Madisound. Any suggestions where to find them would be appreciated. I'm doing googles now to try to find a source.

Try Michael Percy Audio. He shows tow out of the three. Also has a 4700uf 63 VDC which will work fine.

No affiliation, just always received great service.

Thanks J. I'll give him a try.

Digikey or Mouser are the places to go for PS Electrolytics, not the boutique stores. Get Panasonic THA or TSHA, they're very good, 105C rated, and not expensive. That's what I use in my builds.

When I have to use electrolytics, that is. If possible, I use film caps.

Thanks Ait, I'll check them out. I saw the Panasonic's as wondered about them. Good to know someone who uses them.

Ebay is where I got mine, I just needed replacements though. Hard to find somewhere to buy a few, they wanna sell you 1000 pcs.

Yeah, I've noticed that. It's also proving hard to find all three in the same brand. I've found several that make two out of three, but not all three values. I'm not against mixing brands, but I figured having all the same would be better than hoping for a good mix and match.
I need to open up the phono and see what values I need there too. I was just gong to do the PS and see what the difference was, but with sourcing proving to be this tricky, I figure I should go ahead and order all the caps at once.

4700uF/50V

470uF/63V

1000uF/25V

Best of luck

Peter

Thanks Peter, I'll check these out as soon as I can.

nice to note that you are a fellow Apogee user! :-)

I second Michael Percy. He's been great. Knows his business.
Send him an email and follow up in 4 days. he is busy-and I'm glad he is- great asset to someone like you. Take his advice because if he doesn't know-he won't say; but you'll have a hard time finding someone more knowledgeable or helpful.

The Panny's are nice. I've used them before, but my power supply cap of choice is Nichicon, if you can find them.

Michael Percy has the Nichicon.

And as stated in my first post two of the three are exact matches. The third is a 63v rating insted of a 50v.

Hey Mental, can you explain what increasing the voltage value does? Is the uF rating the most important?
Thanks

Increasing the voltage of a capacitor offers greater overvoltage protection, to the cap. Power supplies are generally designed to specific and balanced parameters. Thus; If you intend to increase the capacitance of your filter caps(beyond say 20-30%); you should also look at increasing the amperage rating of the associated rectifiers. Many have blown their diodes/bridges, via turn-on/recharge current overloads. Also- consider the possibility of damage to the power transformer, as a result of the same. It would be prudent to check with the component's manufacturer, regarding the transformer's current limitations. Something else to consider, since you are thinking about the power supply of a device with low current demands: (http://tech.juaneda.com/en/articles/powersupply.html) Something easy to accomplish, inexpensive and with great sonic benefit: replace the diodes or bridge in your power supply, with Cree Schottky diodes.

Thanks Rodman. Great info. I think I'll stick with current values for right now, but this might be something fun to play with later.

BTW: I've dealt with Michael Percy quite a bit, over the years. Sometimes he's hard to get hold of, but worth the effort. Happy listening