B&H 185

[angelodp]

Here is the best schematic I could find for the B&H 185. The item I have is in very good condition. There are numerous posts on the net about be wary of this amp. It has a non polarized plug and no PT. But I do I do se an "ISO" ? Transformer at the input... I think. Question is. Is this tube compliment and general stage worth trying to make a guitar amp.

A

[Phil_S]

Ange,
FWIW, my reaction to that schematic is the I don't think I'd want to get into reworking that amp. I've repurposed a few, but always started with a "proper" circuit that included both PT and OT. Here is a partial list that makes me want to run the other way:
-No PT. Probably no place to mount one if I had one. Cost of a PT.
-If I purchased a PT, why would I go for an ISO trans? Why not rework the whole circuit into something that we know will work for guitar? The ISO is inexpensive, but it could be flushing good money down the drain. You wouldn't need to spend an arm and a leg on a PT.
-OT looks weird with 3 coils. 25L6 is a low power tube. I think you'd be lucky to make 7W from a pair, and the primary on the OT is probably around 2500Ω. I'm not sure what I could sub (with 6.3V filaments, assuming a real PT) for a pair of 25L6 in push-pull to work with what is probably a 5W 2K5Ω OT. And, so, you'd probably need to spring for a new OT. That might cost more that you'd like to spend for a lesser result.

I think, if I had that amp, I'd look to save what I could, which, besides the chassis, isn't much, and put something totally different in it. Or, I'd sell it on eBay and put the proceeds into something else.

Just my 2¢. Good luck with it
Phil

[angelodp]

Hey Phi, yeah pretty much says it all thanks. I thought I might be getting a 285 when I first spotted it. This was a freebie in exchange fo an old speaker cab. Ok.... Movin on

Thanks for the input.

Best A

[thetragichero]

what about something like this? (i would have the filaments on the iso transformer as well)

[Phil_S]

Well, this goes to show what I don't know and somehow I'm not surprised. That Dano looks totally OK to me. What a great suggestion!

Assuming you build a head or combo cab for it anyway, the ISO can go just about anywhere. It doesn't need to be on the amp chassis.

[thetragichero]

then there's this, which i've been building inside an old silvertone reel-to-reel. i wanted something that was a tweedy 50s blues amp to match the vibe of the reel-to-reel (it should be noted that the filter caps are just values i have on hand that i don't use as often)