. Have to admit, that this was the amp that got me started thinking in the amp building direction, since I started reading about all the tweaks, topology, etc.
Before I knew it, I was ordering a TAD 5E3 kit, cleaning the bench from all the small pedal related stuff and wondering how the hell they've built amps with what looked like resin soaked paper and cloth covered wire.
Long story short, after building few amps and gearing for the next build, I thought it is about time to make the BM OD work better with a strat and generally better for my tastes.
The lists of changes is as follows:
- Bass and Mid caps upped to 0.07uf (i.e. 0.05uf in parallel) (thanks to Gary Glassman)
- OD entrance resistance from 120K to 33K (thanks to Alan Phillips)
- Treble cap set to 390pf ceramic (thanks to LTSpice modelling capabilities
). It is interesting that Silver Mica of the same value (measured within 3-4 pF difference) didn't work that well for the overdrive. Cleans were better.- NFB changed to 4K7 & 390R (thanks to countless hours of experiments)
- HRM set as per my preferences - Treble at around 90k, Bass@70K, Mid around 7K
- OD trimmer (or back panel pot for the Ceriatones) is 20.9K to ground
It is currently running with TAD EL34B STR. I checked it with Tung Sol (reissue) 7581, Tung Sol KT66, TAD 6L6GC, a NOS Phillips 7581A, but seems to work best with the EL34s. Currently an EI ECC83 in the PI, waiting for a matched Sovtek 12AX7LPS to arrive and test how it will work out in V3. V1 is TAD 7025WA, V2 Mullard 12AX7 reissue.
Apparently, I have a function generator and oscilloscope coming in as well, so working on the power amp balancing should take less effort (and I can verify my untrusty ears) than it is now. I am happy with the harmonic content, but I feel like more sustain can be squeezed out.
I have F&T caps available and currently contemplating on changing the Holy Grail filters. Will think a bit, read a bit and report back, if changed.
Huge thanks for all the great information and tips sharing to all.
Hope the above serves someone.
Nevermind the playing on the below half decent sample (it is a 335 style guitar with Bill Lawrence pickups something in between P90 and humbuckers). I will put up a Strat sample soon as well (lost the one, I recorded :/)
https://soundcloud.com/synchu/impromptu ... -28ma-bias
Niki
