Sound Labs - Opinions

I've got a line on 1978 A-1's with a 1992 B-1S bass panel
that appear to be in very good/excellent condition visually.
What're the +/- 's for this vintage and combination?
Thanks in advance.
The good all days. A-1, some of the best ever. Never got the bass panels to work properly though.
Had a pair of younger A1s. Sent them to the factory for complete update.

The A1s gave me the best natural bass ever in my room and the overall the best performance with Bryston 7B amps and Pass X600s.

However, even in a relatively modestly sized room, 7Bs (500w/ch rms) would overload if the volume went up a little louder than the normal listening levels. With its original wood core, I could not get them to be like the new ones even at the factory...

If the pair you are considering is in good working condition, I would recommend it. But, if there are any issues with low bug zapper noise from any of the multi-cell sections, I would pass.

You can only tell if you would power up the speakers with proper bias settings and get one of your ears right next to the speakers and listen for abnormally. Next, play some heavy bass material such as the 1st track of Jennifer Warnes' Hunter CD and listen for popping noises...

Thus, these speakers are one of the best when working properly but if there are any possibilities of issues...stay away.

Ki, The older A-1s had impedances in the bass of over 50 ohms. A 500 watt transistor amp will only make about 70-80 watts into that impedance. So you were never able to tap the power of the amp with that speaker.

To really get Sound Labs to sing, you need a tube amplifier that will not loose significant power into the higher impedances. The older Sound Labs IME were easier to drive, that is they were fairly efficient, and their impedance was set high enough so that the speaker could be driven easily by a 100 watt tube amp. So, Rapid, If I were you, that is what I would be looking for at the very least.