• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

PSU Caps for an EL34 SET

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Hi guys,

I am building an EL34 SET with a 450V PSU. I am in search for radial type power caps for the CLC stage. (two 47uF, 500V and one 100uF, 500V) However, I have only come across snap-in type caps online many of which have really short leads and sometimes requiring some mounting hardware. I am trying to keep my construction simple and am using 6 lug terminal strips for point to point wiring on a metal chassis plate. I have some 18ga buss wire. Would it be safe (and possible) to use this copper buss wire to attach snap in type caps to the terminal strips? I intend having all capacitors on the underside of the chassis. I was looking at the Panasonic high voltage caps here. that have short leads? I want to avoid using mounting hardware as it would clutter things up. Alternatively, do any of you know where I could find radial type caps with the ratings mentioned above? The thing is I have never used snap in type caps so I have no idea as to how to work with them. It seems like most 500V rated caps are snap in types for some reason. Any help would be appreciated.

I hope you all are having a fun and chilled out holiday!

Cheers,
Jason.
 
well there are a couple things you can do. personally, i tend to just solder wires to the little prongs on the snap-in caps and use them like a regular capacitor. then again, i always avoid snap-in caps like the plague, preferring the chassis-mount can electrolytics/motor runs or big axials..
 
Ex-Moderator
Joined 2004
If your normal B+ is 450v, then I suspect that 500v working voltage could be too low for your caps. You need to allow a safety margin, so that no cap will be exposed to excessive voltage if the PS is unloaded for any reason. The penalty for allowing this to happen could be the violent destruction of the cap.

I tend to double up on caps, mainly because I haven't found any with high enough working voltage for my needs. I use two in series, shunted with resistors of 220k or so to equalize the voltages. In your case, you could use a pair of 100uF 350v in series, followed by a pair of 220uF 350v in series. Don't forget the shunt resistors; not only do they ensure equal spread of voltage but they also do a useful job of draining the caps when you switch off.
 
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