On Sun, 6 Dec 2020 10:51:11 -0800 (PST), "Peter W."
wrote:

My brother has a very vintage pair of Acoustat speakers driven from what he describes to me as an Acoustech IV pre-amp, distinguished by having phono-jack outputs directly to the speakers. Which have large, heavy, powered boxes attached. After many years of sitting unused, they went silent on him. I suspect the pre-amp, but at-a-distance, I cannot be sure. No, I do not have the model number of the speakers, but they are self-powered, very nearly 2 meters tall, just over 6 feet, There are three fuses on the back, a removable power-cord, an on-off switch, the 1/4" phono jack input and a 5-position treble boost/cut knob. Which should narrow it down.

Question: is that specialized pre-amp required, or would any normal audio pre-amp do?

Thanks in advance!

Peter Wieck
Melrose Park, PA

The preamp isn't special. You'll need one that can do a
reasonable output amplitude, even though the speaker
input impedance is high, as the accustats need good
drive levels.

Having both speakers go silent at the same time does
suggest the preamp.

RL