5AR4 used with four 6L6s?

[JWK]

Here's the deal:

I have an older Weber power transformer for a twin reverb type amp, BUT it has a 5V filament winding. This tranny has taps to get 300-0-300. Now I'm thinking with the voltage drop at idle to begin with and further dropping (what is it, 17 volts or something?) under high current use, the amp might not exceed the 250 mA rating of the 5AR4.

What do you think? Still too taxing on the tube? Maybe. I don't know. I don't have a way of figuring this. I think it would be cool to make a lower power amp with four 6L6s that would have the same power as a two 6L6 amp with the typically higher B+ voltage. It would have a different sound/response, don't you think?

Too much work to go through to have the rectifier tube blow.

Any way of figuring this? Thanks.

[f.leghorn]

5F8-A

Without digging into the math, the 5F8-A Twin uses four 5881s with a single
5AR4 (GZ34). Now that's at close to 400V so the current draw would be higher at 350V. Personally I think a quad of 6L6GCs is pushing it on one 5AR4, especially at 350V. I'd use two in parallel.

[Ray Ivers]

JWK,

If you don't mind going a bit 'outside the box' design-wise, you could parallel each 5AR4 diode section with two 1N4007's in series (one would do it, but with only a small 160V safety margin) along with an additional series resistance sized to draw maybe 100mA or so continuously thru the SS diodes. This would allow the 5AR4 to supply the lion's share of the peak current demands (when IMO a tube rectifier has the most effect on the sound) with the SS diodes acting to reduce the average current thru the tube and let it run a bit cooler, and within its ratings.

Ray