Just received the elusive Ampeg B1 Combo!

[mickebas]

Have never connected extension cabinets. Mine has served 90% of needs as a combo. DI'ed it into a PA on the rare occasions playing outdoors or oversized venues. If it is a well-cared-for combo, you will be happy. Amp is entirely original up until its ongoing power transistor and preamp tube refresh. It replaced a then new, unreliable Gallien Krueger combo and I have never looked back after trading it back to the dealer.

Thanks.
I guess this combo really is only meant to be played as is without an extension speaker then…
or disconnect the amp and use it by itself with a different cab.
It just seems a little strange to me that they put two speaker out connections on the back if there’s no actual way of using it as a combo with an external cab.

 

[Jeff Scott]

Thanks.
I guess this combo really is only meant to be played as is without an extension speaker then…
or disconnect the amp and use it by itself with a different cab.
It just seems a little strange to me that they put two speaker out connections on the back if there’s no actual way of using it as a combo with an external cab.

IIRC, the amp was available as a standalone head, hence the two speaker outputs.

 

[66 Fender Jazz]

IIRC, the amp was available as a standalone head, hence the two speaker outputs.

 

[66 Fender Jazz]

I agree; that is correct. Disconnect the internal woofer and drive your cabinet of choice, keeping above a 4 ohm load.

 

[Jazz Ad]

How would I go about connecting an external 8 ohm cabinet and still have the internal 12’ speaker on?

It goes down to 4 ohms and the cabinet uses a 4 ohm speaker.
If you plug an additional 8 ohm speaker you bring the impedance down to 2.66 ohms, which Ampeg didn't mean to happen.
It may work just fine or release magic smoke. I wouldn't risk it. It's 150w take if for what it is.

 

[Irwelvis]

It's been a minute since anyone asked about B1 schematics, but I thought I'd post a photo of the top of my B1, if it comes in useful for anyone else.

 

[Jazz Ad]

I still think it's the best amp I ever owned. I shouldn't have parted with it, I was dumb.

 

[66 Fender Jazz]

I still think it's the best amp I ever owned. I shouldn't have parted with it, I was dumb.

I agree on your assessment about the amp. Played my '02 StingRay through this '94 B-1, that I purchased new, just last weekend. Recently solved a fuzziness problem that turned out to be board level replacement of the mica insulators for the transistors...NOT the transistors themselves. Also replaced the ORIGINAL pre-amp tubes with nicer, more musical 12AX7s. Would NEVER sell mine. So portable. Original speaker- never abused. Even have the footswitch.

.

 

[Jazz Ad]

Would NEVER sell mine.

I replaced it with a Mesa M3 that had the same form factor with more power. It lacked the versatility and bright, warm tone of the B1 so I didn't keep it.

The B1 speaker doesn't handle B strings very well. It's the only real critic I can formulate. The preamp is magical.