Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: dwp on September 01, 2010, 12:10:50 am

Title: anyone have example of dumble type OD on to tweed 5F6A?
Post by: dwp on September 01, 2010, 12:10:50 am

I'm looking for an example of where or how to insert a full 12AX7 Overdrive, two knob control, level and Drive, similar to D-lite, in to a tweed 5F6A preamp. I don't want to give up a channel.  am studying Doug's hotswitch mod, am not really seeing how to develop level and gain, and insert in second stage. Anyone done this already or is there a reason why it doesn't work so red-hot in a tweed circuit?
     I've built the D-lite, I would like to maintain tweed preamp/tone stack rather than Blackface. Am also using Tubenit's one tube reverb.
Any/All input appreciated.
thanks in advance, dwp

Title: Re: anyone have example of dumble type OD on to tweed 5F6A?
Post by: tubenit on September 01, 2010, 06:37:02 am

Sure you want to do this?  And IF you build this, how about please letting us know how you like it?

With respect, Tubenit

Title: Re: anyone have example of dumble type OD on to tweed 5F6A?
Post by: 67polara on September 01, 2010, 08:50:46 am

The filament resistors are drawn wrong at the transformer.  Most of us know what you meant but the sudo ground won't work that way.

Tony

Title: Re: anyone have example of dumble type OD on to tweed 5F6A?
Post by: dwp on September 01, 2010, 11:31:11 am

Thanks Tubenit. Actually I was thinking in front of the tone stack, inserting switch after 270K's at V2-2. Wouldn't this be a better place to insert the additional gain stages, in front of tonestack instead of after     What's your take on this, too nutso?
     I've found that my EF86 boost scenario is very effective on a two 6l6 build, but not drastic enough on a 4-6L6 build, for whatever reason. Hence wanna try the Dumble OD.
   Your thoughts please?
Thanks again for the drawing, dwp

Title: Re: anyone have example of dumble type OD on to tweed 5F6A?
Post by: tubenit on September 01, 2010, 12:07:28 pm

Man, I don't know what it will sound like?  Never heard of anyone doing this before so all I can tell you is try it if you're so inclined.
 :undecided:

Having said that, I personally do NOT like the HRM tone stack after the OD section and found it somewhere between difficult and useless in achieving the tone I wanted.

You could also try the TOS OD section using the 5879.

With respect, Tubenit

Title: Re: anyone have example of dumble type OD on to tweed 5F6A?
Post by: dwp on September 01, 2010, 12:24:54 pm

Think it might be too HOT? I want to keep 12AX7 as tube type for standard-ness. Will keep you posted, am not near building yet, gotta free up some iron. Am working on my drawing skills, will also try to post a comprehensive .sch when I get there.
Thanks again, dwp

Title: Re: anyone have example of dumble type OD on to tweed 5F6A?
Post by: tubenit on September 01, 2010, 12:59:21 pm

I doubt being too hot will be an issue. You can correct values of components or use a 5751 if needed.

With respect, Tubenit