Converting a Stromberg Carlson AU34 to an Ampeg B15

[Marco17]

I'm working on converting this PA head into a bass amp and I was suprised to see the B15N schematic

Code: Select all

https://www.vintage-blue.com/assets/b15nc_schematic_11_64.pdf

with 0.022uF coupling caps. I thought they would be larger - more like .220 uF. Any thoughts or comments are appreciated. I guess just verifying that there will be enough bass in a 0.022uF cap
Mod edit: removed odd chrome extension part...

[Stevem]

I have a B15BF and with its intended 15” speaker it’s not bad, but don’t try playing a 5 string thru it!

Remember these early Ampegs where first designed to amplify standup Bass.

In the B18 models they went with .05 uf caps.

Let your ears be your guide and audition different values caps in that location, but remember with only some 30 watts of power these where small jazz venue and recording amps, and by the way they make great guitar amps thru guitar speakers.

[Marco17]

Thanks for the tip. Yes, I'm just planning on using this for recording and small gigs. I would like to figure out how to install a DI out as well once I get it up and running. I have restored it and it works fine now. Next step is to modify the circuit into an B15.

[Stevem]

If your talking about a low impedance DI to go to a mixer just get a DI box and save the hassle.

[Marco17]

Yeah, that makes more sense, but I have a couple input transformers from PA restorations and conversions that I "have" to do something cool with.