LEAK Stereo 50 Rebuild

[6B4G]

Hi guys I just picked up a LEAK STEREO 50 and I'm about to venture on a rebuild.
This morning I started as you would with the electrolytic caps (cans), I removed them from the
case and ran (reformed)(leak tested) them on a Heathkit IT-28, they seemed to read correctly threw
all the voltages up to 500 volts, there was a small delay but once I discharged a couple of
times they charged and discharged (several times) quite quickly.
Even though they passed the test should I still change them.
Also there values were within 15% of the written value.

Thanks for your help.

[Shannon Parks]

I use to reform the old Dynaco 500V caps until they were at 500uA leakage current @ 500V. Just for what it's worth. Even when you don't use them, it's kind of fun just to do it.

Shannon

[6B4G]

I know,
But would you trust them in your amp?

[kheper]

If you're re-tubing, I suggest KT66s for the outputs.

http://www.44bx.com/leak/leakStereo50.html

"Only 380 Volts was applied to the anodes, so the EL34's are not working very hard at all. Idle current is around 65mA."

KT66s sound good with a high, idle bias > 50ma. Check the anode voltage. Since line voltages (at least in the US) are higher than the 1950s, I'll wager the anode voltage is greater than 380V. Leaks used turret boards in their amps, so replacing caps should be relatively easy. On ebay, Leak Stereo 50s go for about $1500.

[Shannon Parks]

I know,
But would you trust them in your amp?

If reformed and showing low leakage current, they don't worry me. The 5AR4 will blow first. :^)

Shannon

[6B4G]

If reformed and showing low leakage current, they don't worry me. The 5AR4 will blow first. :^)

sounds good.
The amp came with new TAD EL34B STR tubes and GZ34 STR- any comments on these tubes?

[Geek]

If reformed and showing low leakage current, they don't worry me. The 5AR4 will blow first. :^)

5AR4's go up like an old Kodak "Instamatic" flashcube. Would be fun to see!

[6B4G]

Got another question.
I want to install in place of the existing caps 2X Mundorf 15uF+15uF 450V M-Lytic HV
as the originals are rated at 500V and the voltage at the first cap is 408V would this be a problem?
There is approx 12% headroom is that enough?

[Shannon Parks]

Since you have the slow warm up action of the 5AR4, you'll be fine (i.e. no peaking B+ with no load, cold tubes).

Shannon

[6B4G]

Thanks Shannon but if I was to use a GZ34 would it also have the same characteristics as the 5AR4 as the warm up time?

[Shannon Parks]

Thanks Shannon but if I was to use a GZ34 would it also have the same characteristics as the 5AR4 as the warm up time?

Yes - they both will have a 30 to 45 second warm up time. Very tube amp friendly!

Shannon

[6B4G]

Thanks for all the help