output stage standby query...

[ioginy]

Good day all.

I am working on a bass amp for live/recording that uses a rotary switch to jump between triode, U-L and pentode. sadly I could only find a 4 position / 3 pole switch. This is great except it means I am left with a "click" on the switch that does nothing. I thought it might be a nifty idea to use that poition to mute the output stage but allow the preamp to still funtion, allowing the "line out" to still be usefull for preamp recording.

I'm not sure if it as simple as I think it is, but these are my ideas; I don't think it would harm the tubes to disconnect the OPT from them, so leaving the connections "open" giving the signal no path from the plates to the OPT is one of the options. The other is a "standby" system used by Silvertone where the grid wires are shorted together. Here is an example of this.

http://www.prowessamplifiers.com/schematics/silvertone/Silvertone_1483.html

If this is a completely hair brained idea, i'll figure out some other way of using the switch, but if it's feasable, I would love to hear anyones thoughts on it.

Thanks.
Cory

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edit
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I just realized that it would be the screens that I would be the second screens that I would be leaving disconnected, so that idea is no good. Looks like the "standby" option is all I have right now.

[dhuebert]

I would short the control grids to ground.

Don

[dhuebert]

What are you doing for line out btw? I've often thought about this on my own amps.

I had good luck with this:

http://www.jensen-transformers.com/as/as021.pdf

Don

[ioginy]

I used the Weber design for the tube buffered affects loop (i'll see if any adjustments need to be made when it's all hooked up). I also ordered the weber balanced output transformer and am using their suggested design as well. It seemed to fit well with the amp, but we'll see how it works. I'll post a schematic if you want to take a look.

[ioginy]

in fact, on the note of the balancing transformer, i was wondering about the orientation of it, if you'd be able to give me some insight. Here is the info sheet on it;

https://taweber.powweb.com/store/balun.jpg

I was wondering if, when using the red dot as reference, if 1 is the pin represented by the red dot, if 2 would be the pin along the .775" side or if it would be the pin along the 1" side. I figure it's the .775" side but I thought a second opinion wouldn't be a bad idea.