Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Jp phelps on December 26, 2016, 02:46:51 am
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I noticed in the layout there's not one, how does the vibrato work?
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The low frequency tremolo signal wiggles the bias of the output tubes.
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Is there any major difference in doing it this way vs a coupler? Can it be just as smooth without any tick tick tick like you get on a coupler if your wires aren't right?
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It's smoother than the neon bulb/LDR roach. No tick. Can be difficult to get a strong tremolo effect and 'proper' bias setting with 6L6s.
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I noticed in the layout there's not one, how does the vibrato work?
"The Hoffman AB763 turret board does have one major difference from the original Fender AB763 circuit. The Hoffman AB763 turret board uses the Tremolo section from the Fender 6G16 Vibroverb (http://el34world.com/charts/Schematics/files/fender/Fender_vibroverb_6g16_schem.pdf). This is not an opto isolator tremolo. This 6G16 tremolo circuit pulses the power tube bias voltage up and down. This tremolo method sounds way better than the opto tremolo to me. It is a very smooth tremolo. You can look at the 6G16 Vibroverb on my schematics library page to see the differences between the 6G16 tremolo and the opto isolator tremolo found on most Fenders. Most people like the 6G16 tremolo way better than the Opto Tremolo."
info on the Hoffman AB763:
http://el34world.com/Hoffman/AB763Notes.htm (http://el34world.com/Hoffman/AB763Notes.htm)
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Is there any major difference in doing it this way vs a coupler? Can it be just as smooth without any tick tick tick like you get on a coupler if your wires aren't right?
Like Sluckey said the tremolo effect is really weak, and also makes it harder to bias the amp with 6L6 tubes.
The effect is so weak that the first time you try the amplifier you become really disappointed. The stock tremolo circuit in the Hoffman AB763 simply doesn't work with 6L6.
I did Sluckey's Mods (Notes 1-4) on the tremolo and it improved but It's still really weak and I personally dont like it, so I can't really advise it to someone who is building this amp with 6L6 power tubes. I prefer the optocoupler tremolo.
I will just try Sluckey's "Note 5" mod see how it sounds before changing the Vibrato circuit for the Fender Opto one.
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Is there any major difference in doing it this way vs a coupler? Can it be just as smooth without any tick tick tick like you get on a coupler if your wires aren't right?
Like Sluckey said the tremolo effect is really weak, and also it makes it harder to bias the amp with 6L6 tubes.
The effect is so weak that the first time you try the amplifier you become really disappointed. The stock tremelo circuit in the Hoffman AB763 simply doen's work with 6L6. ...
I've never really tried it with 6L6's (not for any length of time to evaluate it). But it is nice & deep on a Princeton/Princeton Reverb (the 6V6's use less bias voltage, and so are easier to trem).