Re: wiring FrankenVox AC15 for 6AQ5's and 6BQ5's?

Phil S. wrote:

I'm getting near the end of the FrankenVox AC15. The plan is to wire a pair of 7-pin sockets for 6AQ5's and a pair of 9-pin sockets for 6BQ5's. The questions::

The 6AQ5's call for a cathode resistor of 250z and the 6BQ5's call for 130z (in this case it will be 125z). In doing the wiring, is this as simple as wiring one 6AQ5 and one 6BQ5 from each pair in parallel. I assume this works, as long as only one pair or the other is present in the sockets. Then, wire the cathode with two 125z resistors, one of which is on a bypass (on-off) switch?

I'll be using 1.5K grid stoppers and 100z resistors of G2, both tied directly to the tube pins. These will be present on all four sockets. Is this a problem? Or is it better to simply pair up one 7 and 9 pin tsocket and wire strictly in parallel, essentially using the (one set of) grid stopper and G2 R to do double duty?

Or is it necessary to to something more elaborate to get this right? I understand that the user needs to know to only have one pair present in the circuit, and that will only be me. I can always write on the head with a Sharpie to keep unlikely fools from thinking one could acutally run this amp with 4 power tubes. There isn't enough B+ or filament supply for it, not to mention how they might interact. If I like it better one way or the other, I can look at making it into a Frankenvox AC30 <grin>.

It is possible that I'll have to supplement the filament supply as it is. I saw a nice small 6.3v 0.3A tranny in Radio Shack for $3.99. It is PCB mount, so it will require a bit of ingenuity to make it useful.

Thanks for comments and advice.

Phil



If the existing filament winding is weak anyway, have you thought about a completely separate filament transformer, so that you can play with a variac for the rest of the circuit?
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