Fender The Twin Red Knob reconstructed

[MartinS]

Hallo Community,
after buying some parts of a Fender The Twin Red Knob in the famous bay I brought this amp back to stage. It was a big and long running project. But the result is convincing. At least to me.
While reconstructing I investigated in several issues:
• How can the cooling of chassis be improved
• How to modify the amp to run it with 65% of max. heat dissipation of the power stage.
(According original Fender design the power stage runs at 30% of max. heat dissipation)
• How to “tame” the 100W of this really loud amp
• To reduce Hum to an absolute minimum I made a lot of investigations. Not all successful. I thought I would achieve more.
• To use the Standby switch in this amp only after at least 10sec warm-up phase is mandatory to avoid voltage overload during each tube warm-up cycle.
• I modified a common cheap foodswitch for the Red Knob specific ones.
The amp was totally characterized in chap. 4 of the detailed report to which you can have access by using the link below. This makes life easier for repair work.

Here the link to the detailed report of the project:
https://drive.google.com/file/d/19Xuwgr ... drive_link

[martin manning]

Nice work! Looks interesting, but will take some time to read through. Executive summary on p. 95 ;^)

[maxkracht]

Thanks! I have a couple "the twin"s in my shop at the moment. I don't plan to do that much work, but your writeup might come in handy.

[Lynxtrap]

Impressive work!

[Seb C]

Where was this thread six months ago??? Looks great

I bought one of these just before Christmas, very cheaply, broken. A lot of the power tube wiring was missing, and three of the main filter caps had failed open. Lots of ground issues and dodgy wiring (the multicore stuff they used seems to be pretty crumbly by now. Who knows whether it was any good when new or a cost-saving measure).

I'll have a good read, not least on the bits about hum (mine is too noisy, and worse with the reverb up).

I have to say, I like the amp but don't love it - but that wasn't the plan anyway. It's probably still destined to become a SSS clone this year (but mine is much less clean than yours so not really a shame to re-purpose the iron).

[WhopperPlate]

One of my favorite guitarists , Jim Thomas from the Mermen , played these amps live and on many great recordings . He would run six heads each into one JBL d130. Great feedback and overdrive tones , but ultimately had to be replaced because of inconsistent and unreliable performance.

This is a great educational material for approaching these amps , thanks for sharing

[MartinS]

Hallo,
Thanks for your feedback.
In deed it took me one and a half year to realise that project.

[romberg]

Very impressive amount of quality documentation! I'm sure anyone working on the insides of one of these would find your document to be extremely useful. I wish something like this existed for some of the amps I've been inside.

Mike