Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Diverted on October 05, 2020, 12:58:31 pm
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I have built a few Fender Champs recently (5F2As) and they're a lot of fun. I was thinking about adding the Fender reverb into the circuit and found this thread:
http://ampgarage.com/forum/viewtopic.php?f=6&t=30988
It's a great help. However this version uses the Fender Princeton treble/bass tone stack. I would like to use an original single tone knob stack instead, as in the 5F2A. If I switch around the preamp stage to a 5F2A style stack, will that affect gain characteristics? I'm wondering how much signal loss is generated by the Princeton-style treble/bass stack and whether using the 5F2A tone control would be too gainy.
Also, as I'm trying to fit this into a small form factor, I was thinking about going with a solid state rectifier instead of a 5Y3. The power transformer for this amp, with a 5Y3 rectifier, has a 330-0-330 secondary. Should I shoot for about 310-0-310 secondary if I'm going with a SS rectifier? There's a company called Musical Power Supplies here in the US that can wind custom transformers, so I can pretty much get any winding I want.
Thanks!
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You might want to do a search on this forum as this topic has come up many times over the years.
With respect, Tubenit
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I did thanks, but didn't see any posts w/respect to the tone stack. I'll keep looking then.
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....w/respect to the tone stack....
Why does it matter? If I read that other thread correctly the reverb isn't near the tone network.
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I wasn't worried about it w/respect to the reverb.
I was wondering about the gain difference between the two tone stacks because I thought one or the other might cause less or more gain overall in the amp. If the single tone pot is a hotter tone stack than the princeton, that would cause earlier breakup which I was trying to avoid. And since I was hoping to build it with the single tone pot stack, that would need to be something I'd have to account for. Thanks,
Ted
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You can build a James tone stack (sometimes mistakenly called Baxandall tone stack) using a dual gang pot. So you have "one" pot that can do both mid scoop tones or accent the mid tones. It will have more loss to it and also help lessen the gain with the mid scooped tone.
You can change pot values with a resistor across the outside lugs. Doing that you can approximate both a 250k or a 500k using a dual gang 1M pot.
Look at the Duncan tone stack calculator to see what values you want to use.
With respect, Tubenit
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Thanks, Tubenit. Once I get it together I'll start experimenting to see what's best. Thanks for the tips.