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Discussion in 'Shock Brother's DIY Amps' started by hackworth1, Feb 13, 2018.
This project utilizes the standard 5E3 board from a Boot Hill kit. I wanted to see if I could fit the Tweedle Dee Circuit on a typical board. I also installed an adjustable fixed bias circuit on the left side.
Nice, Dave! Great to see that you can fit the Tweedle Dee on a typical board of yours! Cool!
What is the tweedle dee circuit?
I like the idea of using a trimmer for the phase inverter balance control.
It's fairly common in D style amps (especially with LTPI) and IMO, a major part of one of those 'small things' that makes the Dumbles stand out from 'regular' amps. I have a PI balance pot on my twin, with some other Dumbly tweeks. You can run it clean and get that sustaining feedback-y bloom stuff super easily. The amp just seems to want to blast off. It takes some tuning, though, and I don't have a scope to do it on, so I typically have to tune by ear, for this part. On a scope, you're looking for enough imbalance that the 2nd order harmonics stop being suppressed in the PI. (A perfectly balanced PI will cancel some noise and even order harmonics in the PI) The added even order harmonics in the output section seem to make the amp have much of that 'singing' quality.
Hope we can get a test drive sound clip of this one Dave. Very innaresting indeed!
Objective to increase clean headroom with more filtering - ergo a 32/32 uF F&T cap can in the rectifier hole. Solid State rectifier is built with four N4001 diodes on a terminal strip to convert AC to DC. A 270 ohm 10 W resistor is in place for the sake of R/C coupling.