Hi all,
I'm semi-interested in a 6G16 brown Vibroverb build. I've done a Super Reverb AB763 build about a dozen or so years ago so not a complete stranger to Fender builds.
But, I am learning that one of the big issues with bias-vary trem for the 6L6 based amps (e.g., 6G16, 6G11/A, etc.) is that the amp is either biased to have a great tone (hotter bias) or great trem (colder bias).
IOW, I can't "have my cake and eat it too", apparently... or can I?
Stupid idea/question but I was thinking to have a switch (DPDT) to toggle between cold and hot bias settings. Then, I could have my cake and eat it too?
I would most certainly be interested as to why this would be stupid/wouldn't work.
Thank you in advance.
Switching bias on a bias-vary trem 6L6 Fender (e.g., 6G16, 6G11/A, etc.)
Moderators: pompeiisneaks, Colossal
Re: Switching bias on a bias-vary trem 6L6 Fender (e.g., 6G16, 6G11/A, etc.)
I would simply add a resistor (or make it a resistor and a trim pot) to ground from the output of the bias filter network with a switch between the resistor and ground. That way the output tubes never see a condition with no bias. If you were really clever, you could make it so the hotter bias is activated by the tremolo footswitch when the tremolo is switched off.
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Re: Switching bias on a bias-vary trem 6L6 Fender (e.g., 6G16, 6G11/A, etc.)
A fairly low bias is your friend with brown amps.
Overbiased Fenders. Yuck.
Overbiased Fenders. Yuck.
Signatures have a 255 character limit that I could abuse, but I am not Cecil B. DeMille.
Re: Switching bias on a bias-vary trem 6L6 Fender (e.g., 6G16, 6G11/A, etc.)
Cool. Thanks for that.LOUDthud wrote: ↑Tue Feb 13, 2024 10:43 am I would simply add a resistor (or make it a resistor and a trim pot) to ground from the output of the bias filter network with a switch between the resistor and ground. That way the output tubes never see a condition with no bias. If you were really clever, you could make it so the hotter bias is activated by the tremolo footswitch when the tremolo is switched off.
Would a shorting type toggle switch help?
Re: Switching bias on a bias-vary trem 6L6 Fender (e.g., 6G16, 6G11/A, etc.)
A picture = 1k words.LOUDthud wrote: ↑Tue Feb 13, 2024 10:43 am I would simply add a resistor (or make it a resistor and a trim pot) to ground from the output of the bias filter network with a switch between the resistor and ground. That way the output tubes never see a condition with no bias. If you were really clever, you could make it so the hotter bias is activated by the tremolo footswitch when the tremolo is switched off.
Am I on the right track here?
Re: Switching bias on a bias-vary trem 6L6 Fender (e.g., 6G16, 6G11/A, etc.)
That would work except you might get a loud thump when you throw the switch. Leave one resistor connected all the time, then connect the second resistor for hotter bias.
Re: Switching bias on a bias-vary trem 6L6 Fender (e.g., 6G16, 6G11/A, etc.)
OK. Do you mean the second resistor switched in parallel?