Tremolo question for Sluckey

[punkykatt]

Will the 6G16 Vibroverb tremolo circuit work  in a  dual 7591 cathode biased amp?  The two 220k grid to ground resistors to the power tube grids will be lifted from ground .  Connect the 250kl intensity pot  wiper to the  220k  junction? Just wondering.   Thank you in advance for your time and help.  Punky

[sluckey]

I see no reason for it not to work. The 7591 is very easy to wobbulate. I put the 6G16 in a fixed bias 7591 amp. Trem is very strong.

Connect the 250kl intensity pot  wiper to the  220k  junction?

Yes. And the end of the pot that would normally connect to the bias voltage will simply be connected to ground.

[punkykatt]

Sluckey,  thank you very much. Yes i will ground that end of the 250kl pot.

[basschops1528]

I'd like to ask a question as well. On your tremolo mod sheet, what is the difference between the top and bottom circuits; or the significance. I understand the notes as they are described to the right but don't get what the top circuit has to do with the rest.

[sluckey]

I'd like to ask a question as well. On your tremolo mod sheet, what is the difference between the top and bottom circuits; or the significance. I understand the notes as they are described to the right but don't get what the top circuit has to do with the rest.

I don't know which tremolo mod sheet you are referring to. Can you post a link?

[basschops1528]

Sluckey's AB763 Tremolo Mods

http://el34world.com/Hoffman/files/Hoffman_AB763_Mods.pdf

[sluckey]

Look at the red circle. The circuit on the top has a different footswitch arrangement that is tied into the negative bias voltage. It's similar to the true AB763 trem footswitch. It requires the footswitch to be plugged in just like the AB763 in order to enable the trem. The benefit of using this type footswitch circuit is that the oscillator will start up almost instantly when the footswitch is closed.

[basschops1528]

So when you do the mod, you move the footswitch between that 1M/2.2M divider, connect the 2.2M to the bias, THEN address Notes 1-5?
When the top says "Modified" I assumed the circuit would present all the changes in the Mod, and when it didn't I got confused.

[sluckey]

I didn't create that pdf file. I did the drawings and table but I never combined all that info on one page. The drawing at the top deals with modifying the 6G16 trem oscillator so it turns on instantly when you kick the footswitch. The table is a suggestion of things you can do to 'improve' the 6G16 trem circuit if you find that your trem effect is too weak and also what to do to slow the speed of the trem. The table of notes goes along with the circuit at the bottom of the page. I think maybe Doug combined those two files into a single pdf file?

Bottom line, that file is just a collection of suggestions for things that may improve the 6G16 tremolo operation. It's not meant to do all those suggestions as a single mod. You can do any one of those suggestions, a combination of any of those suggestions, or all suggestions at once. I would advise to only do any of those changes ***IF*** you have a need, ie, trem effect starts slow, or trem speed is too fast, or trem effect is too weak (and bias compromise will not get the trem effect strong enough to suit you).

[basschops1528]

Thanks Sluckey. Very good to know.