Ampeg B-12 vs. SB-12

[gwailoh]

Can anyone elaborate on the differences between the B-12 and the SB-12? Circuit, speaker, features, etc.?

Are they both using 7868 power tubes?

Also I've seen some SB-12s with blue diamond tolex and others with black, all purporting to be '60s vintage. Is there rhyme and reason to these differences?

Thanks!

[teleharmonium]

There are multiple versions of both the B12 and the SB12. The Ampeg book is a fun read if you really want to geek out.

Based on the examples of each model that I have known, as well as having read the book cover to cover (but not recently), I would say that the B12 is a dual channel amp in varying speaker and tube configurations, while the SB12 is a single channel minimalist amp. I've seen SB-12 that used 7591 (7868 is basically the same tube with a different base). There might be 6V6 or 6L6 versions, I can't remember. I own a B12X which has a 6L6 based power amp (I forget exactly which version of 6L6) and has a single 12" plus a sattelite cabinet with two small speakers for the reverb only signal. The B12XT is a more common later version.

Ampeg coverings in the relevant time frame started out as dark blue "random flair", then blue diamond, then black, by somewhere around '67 or so.

The SB-12 is a simple amp that sounds good so long as the amp is healthy. Some of them use the very questionable approach of actually running the speaker connection through the metal latches that hold the head to the cabinet; these have been known to go intermittent, which can cause output transformer death. Personally I would avoid those models, or possibly have one modded if I could find a reasonably graceful way of doing so. The people at Ampeg thought "out of the box" but sometimes it was "on the bottle".

My B12X sounds great for bass at low ish volumes, or for guitar. I assume the B12XT would as well.

Many of the Portaflex models don't have any handles on the sides of the cabinets, which makes them not so portable really. It's the sound of the amps that made them famous, not the goofy cabinet concept. I don't recommend hauling them by the handle on the underside of the board where the head resides, because those little latches don't seem like they should be bearing that kind of weight. If I need to move my B15 or B12X, I transport the head and cabinets in separate trips to/fro the car.

[themaidsroom]

Originally Posted by teleharmonium

.
It's the sound of the amps that made them famous, not the goofy cabinet concept. I don't recommend hauling them by the handle on the underside of the board where the head resides, because those little latches don't seem like they should be bearing that kind of weight. If I need to move my B15 or B12X, I transport the head and cabinets in separate trips to/fro the car.

you got that right.

i had my B15 head repaired this
summer and i moved it via public transport
and a plastic bag - it was a truly unpleasant
experience - august manhattan