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View Full Version : Bogen CHB 35A tricks?


dusty tolex
05-10-2008, 01:28 PM
Hi,

I just grabbed one of these old tube mono PA amps, in apparently fine condition. It has already been modified to accept RCA plugs for a speaker (the seller was using it as one channel of a stereo; he was trying to locate a second unit for the other channel but was unsuccessful). With a few adaptors I can hook up a 112 cab and play my guitar through this thing - the cleans are really sweet when I use a preamp (I'm using a Traynor TR-2 ss reverb tank, which has a preamp) in front of it. I do note that the sound is a little less airy than I'd like, it's a wee bit boxy. I find I run the treble full out and the bass rolled back to zero.

I'm still learning about electrical mods to amps in general, but I wonder if, while I learn through lots of reading etc., there is any mod I can or should do right away. I know I need to open it up and inventory the state of the electronics, at the very least.

Any and all thoughts appreciated!

dt

SatelliteAmps
05-10-2008, 03:58 PM
Put bypass caps on the cathodes of the preamp tubes. 25uf @ 50v should be good.

dusty tolex
05-11-2008, 07:19 AM
Put bypass caps on the cathodes of the preamp tubes. 25uf @ 50v should be good.

Thanks for the tip SatelliteAmps!

Er, couldja give me an idea what that would do? Does this have anything to do with "cascading the first two gain stages together"? Also, where would the other end of the caps be soldered to?

cheers
dt