Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Diverted on July 27, 2020, 01:17:27 pm
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Hi all,
Just powered up a Hoffman single channel AB763 circuit for the first time, using the Hoffman board. All works reasonably well except for tremolo intensity, which is quite weak. I need to crank the intensity to 10 to get a usable tremolo, and even then it’s not too strong.
I’ve had luck reducing the value of the 1M to plate resistor on the standard 1/2 tube Fender bias wiggle tremolo, and also had luck swapping out the cap/resistor network on that circuit’s cathode with an LED, to increase intensity. This is a different bias wiggle tremolo, and am wondering about strategies to beef it up a bit.
The amp has a 2x6L6 power section. Tubes biased around 55 percent at the moment. I have also installed at Trainwreck (Lar-Mar) type master volume. If I turned down the MV, the tremolo is much more pronounced.
Thank you!
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The LED trick should give you a good intensity boost. Keep in mind that 6L6s are pretty difficult to wiggle. Play with the bias to find a compromise between optimum bias and acceptable tremolo.
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And if all else fails, you may be interested in this simple mod. I have the schematic/layout if interested. Listen to this...
https://el34world.com/Forum/index.php?topic=26246.0
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Diverted, wich LED circuit did you use ?
http://sluckeyamps.com/trem/trem.htm
Sluckey, congrat for your great circuits found by chance: http://sluckeyamps.com/misc/Amp_Scrapbook.pdf
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And if all else fails, you may be interested in this simple mod. I have the schematic/layout if interested. Listen to this...
That sounds great. Sure, I would love to see that mod, thank you!
https://el34world.com/Forum/index.php?topic=26246.0
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Diverted, wich LED circuit did you use ?
http://sluckeyamps.com/trem/trem.htm
Sluckey, congrat for your great circuits found by chance: http://sluckeyamps.com/misc/Amp_Scrapbook.pdf
Parole,
On the standard 1/2 tube Fender bias tremolo the mod is to replace the tremolo oscillator cathode cap/resistor with a red or white LED. I can attest that it really needs up the effect. It’s Sluckey’s mod I believe.
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Parole,
On the standard 1/2 tube Fender bias tremolo the mod is to replace the tremolo oscillator cathode cap/resistor with a red or white LED. I can attest that it really needs up the effect. It’s Sluckey’s mod I believe.
Thank you
- Latole :laugh:
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This mod is meant for Hoffman's single channel AB763. No changes were made to the turrets. But there are several changes to the components and the board jumpers. This will also work better if you use a 50K-RA INT pot. Just follow the layout and schematic.
BTW, I have modified drawings for Hoffman's 2 channel AB763 as well as his Princeton Reverb.
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On the standard 1/2 tube Fender bias tremolo the mod is to replace the tremolo oscillator cathode cap/resistor with a red or white LED. I can attest that it really needs up the effect. It’s Sluckey’s mod I believe.
Actually it belongs to Merlin. Scroll to the bottom of this page...
http://www.valvewizard.co.uk/trem1.html
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Parole,
On the standard 1/2 tube Fender bias tremolo the mod is to replace the tremolo oscillator cathode cap/resistor with a red or white LED. I can attest that it really needs up the effect. It’s Sluckey’s mod I believe.
Thank you
- Latole :laugh:
Ha! Sorry. My phone likes to change words on me🙄