Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: The_Gaz on March 11, 2012, 03:03:06 am
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I'm gonna build a reverb channel only blackface Twin, and I was thinking about adding a Dwell and Tone control along with the normal Reverb control. I think the both additional controls could be cool, but I was wondering if anyone's added a Dwell and if they find it useful.
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The Allen Old Flame is like a blackface amp with a dwell control.
I did a similar circuit just recently (see attachment). The way the circuit is incorporated BF style into the amp means that the effect of the dwell control is mainly subtle at lower volumes, but comes more into its own as you crank the amp (because more input signal is going to the dwell control/reverb driver stage).
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I haven't added a dwell to a blackface circuit. However, I've owned and played a LOT of reverb-equipped blackface amps, as well as previously owning a Fender outboard reverb.
In the blackface amps, I rarely turned up the reverb beyond 3 or 4 (except for a special effect), because the reverb was so cavernous it didn't seem useful to simply add a little more body around the guitar sound. The standard circuit is equivalent to dwell on full.
In the outboard reverb with a dwell control, I often turned the reverb much higher, because the dwell could be lowered, which allowed more reverb but a quicker decay. I had also replaced the long-delay stock tank with a "6-spring" (really 6-springs arranged in 3 delay lines) medium delay tank. It gave a richer reverb quality with a slightly faster decay which allowed more useable range to the reverb. To my ears, the reverb sound is much better than, but different than, the stock reverb sound of Fender blackface amps.
I think adding a dwell control will allow you much more range of use from the reverb circuit. If it were my amp, I'd include it.
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Interesting thought. Checked out Tubeswell's schematic, the AB673 & the 6G15 circuits as well.
Would this really be as simple as just replacing the 1M resistor in front of the reverb driver with a pot?
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Yes. So simple.
I´ve donne in my AB763 (pro-reverb clon) and worth it.
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Thanks for the advice - in it goes! The only annoying part is having to run the wiring up to the front panel and back. I think I'll live :)
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Yes. So simple.
I´ve donne in my AB763 (pro-reverb clon) and worth it.
Yes, thanks. Sounds like a good thing.
I was just about to start drilling a single-channel AB763 chassis for pots, etc this week, so this was just in time to change the layout.
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FWIW here are some gutshots of the layout of that amp that I posted the earlier schematic for
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Awesome, looks great! I LOL'd at the one mustard cap :) Nice touch.
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Awesome, looks great! I LOL'd at the one mustard cap :) Nice touch.
Was more like which parts I picked up when I dipped my fingers into my stash.
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My experiments with a Dwell control in a Princeton Reverb had results similar to HBP's. I used a Ruby "3-spring" (actually 6) medium delay tank. WAY too much reverb with Dwell on full, but more control and a broader range of results diddling with the Reverb and Dwell controls together.
Cheers,
Chip