Bogen CHB-50 to heavily modified Princeton.

[Boogdish]

I bought this as a "broken" amp off eBay in November for $25. The circuit is sort of loosely based on the Princeton AA964.

Differences are:
No tremolo
No negative feedback
Bypassable extra gain stage in front (just plug in the other jack to bypass it)
6L6GCs instead of 6V6s
Slightly different tone stack values
weird old Bogen power section with voltage multiplier style rectifier

I finished this today and haven't had a chance to really give it a good work out, but I like it so far. It's very quiet, even with the extra gain stage engaged. I can crank the extra stage and then use my normal volume control as sort of a master volume for getting a nice lower level overdrive, and i can get nice cleans from it as well.

This was my first conversion and also my first time doing all point to point wiring and I really really enjoyed it.

Note: some of these components are vestigial from when this was a PA.



Now that this is done, it's time to start planning the next build!

[gldtp99]

Cool idea---- i've converted many CHB50's and CHB35A's to other circuits---i like to see what others come up with with these amps.
i recently finished an AA964 Princeton-ish build myself, no pics yet--- my amp is a 30 watt 6L6GCx2, cathode biased, no Trem---i built it with a variable NFB pot but i've found that i like the amp with no feedback-- so i'll remove the NFB circuit, Pot and use the front panel hole for a crossline MV.
i used a PT from a Dukane 30 watt PA head and an OT from a similar, but older, Stromberg-Carlson PA head--- an AES 125C1A choke.
Amp has a rich, creamy tone and is a blast to play---i built it on a new Hammond steel chassis w/turretboard.
The other night a friend stopped by my workshop looking for "something better" for his stage amp, w/his Strat (plays Texas Red Dirt music)--- he played several amps but liked a Bogen CHB50 converted to a Fender 6G7-A Brownface Bandmaster circuit (no Trem) the best--- he also uses an Ibanez multi-effect unit and has a limit on his stage volume due to their band sound engineer---we now have plans to build a Brownface Vibrolux-type amp into a blown solid-state 2X10 Ibanez combo i have laying around.
We found that he was getting the best lo-vol tone with the CHB50-based head----- he played a 15 watt AA964 JJ 6V6S head i built with a nice 60's Schumacher 4/8/16 OT that sounded great but he was getting more sustain/harmonics out of the CHB50-based 6G7-A..............gldtp99