Fender Princeton Reverb

malherbechris

Hey Guys!

I am looking for some advice on a Fender Princeton Reverb that I am building.

I am building it on a Elk Stageman 30 which is a FPR knockoff from Japan made in the 60s as far as I know.

Okay two questions:
1. The big cans, most Fender amps has 4 22 uF 500V tin can caps in the power supply. It seems in the schematic from Fender that 450V caps was specified in this position and as I understand these caps are able to take a bit more since they are in parralel with the 1 ohm balancing resistor in between.

Source:
http://www.amparchives.com/Amp%20Archives/Fender/Schematics/Fender%20Princeton%20Reverb%20Schematic.gif

So I have found 22uF 450V caps at Communica:
http://www.communica.co.za/Catalog/Details/P1425839557

So my question is, can I use 4 of these capacitors replacing the 4 500V cans? And, will it affect anything? I know that the Power Amp section is very sensitive to changes in filter caps. I have done a search and a guy said that he used similar caps and the bottom end improved, I don't know.

And also is there response wise a difference between the Aluminium big cans and these small electrolytics or is it all about the Big cans looking cool and original?

2.
The caps that came with the Stageman:

I am building a new turret board replacing all the resistors and oil filled capacitors in the circuit with new carbon film (mostly) resistors and new electrolytics since those oil filled ones are failing as I read. I am wondering about the poly caps in there they are brown square ones and look quite decent, I do not want to replace them If they are of good quality and sound good. Does anybody have some experience on the stock Elk poly caps?

Here is an image of the guts I got from the web. You can see the rectangular brown caps I am referring to in the pic.

Thanks guys!
It is really great to have a forum in South Africa where we can get some great advice from knowledgeable people.

ezietsman

Judging from the schematic there will be 450V DC in parts of the power supply so using 450 V caps is cutting it a bit close. You should be able to get 500 or 600V electrolytic caps somewhere. Maybe phone Communica (or check RS's website). My Tweed Deluxe has those fat orange things in it. Don't skimp on these things.

As for the other ones, if they still work (and they probably do), use them again if they're the correct values. That should be fine. Only some of the capacitors are in the signal path and their age may or may not have much effect on the sound. The values are what is most important.

Another forum member is actually planning to do a Fender Princeton conversion from an Elk too. He got the Elk the other day.

Good times!

Attila

450's will suffice ....... I pick up nothing more than +420vdc bearing in mind that the caps are most likely 20%ers so you most prob would need a 20% gap from the marked rating

Wizard

I've got an Elk ES30 that was converted to a Princeton.
Was owned by Keira and conversion was done by JP le Roux.

Karel-Mars

I would also go with Atilla's advice. 450V should be good.

In my experience, electrolytic filter capacitors are a bit like shock absorbers in a car. If the shocks are old, the bass in your amp is less controlled, and more 50Hz leaks into your audio signal. You do not need to change the values. More capacitance in the power supply gives you a darker amp, not always the outcome you need.

I would also replace all the oil caps, since they are leaky and unreliable. Regular polyester or polypropylene types are good. Orange Drops or yellow Mallory types are the best.

Is there a tube rectifier in the ELK? Maybe a 6CA4?

Attila

In case you are looking for a 22uf 450vdc in an Axial package

http://za.rs-online.com/web/p/aluminium-capacitors/7076455/