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Vintage Asylum Classic gear from yesteryear; vintage audio standing the test of time. |
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Vintage Asylum Classic gear from yesteryear; vintage audio standing the test of time. |
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In Reply to: ACUSTECH AMP KLH MODEL 15 TUNER posted by DENNIS FAWCETT on December 31, 2003 at 18:15:18:
Dennis,The Acoustech amps were the very earliest of the solid state amps. The designs are pretty basic. It would help me with advice, if I knew the model number. The model I is not worth fixing or modifying, but the Acoustech IV is a nice 40 W/ch integrated amp and can be modded to be a good performer. I have the schematic for the modified model IV. They were available wired and as kits. They are easy to work on as a result of being designed for kits. The company history is kind of interesting. Up in the Boston area, there were a large number of electronics firms (still are) back in the early 60's. In 1962, there was a large number of layoffs in the area, and a group of EE's found themselves out of work. They got together and formed Acoustech. I believe the Acoustech I was the first commercial solid state amplifier. It was fairly powerful, but because silicon PNP transistors were not available, it used a germanium PNP in the driver stage. All the amps were capacitively coupled and had uni-polar power supplies. They had a reputation for being unreliable. The problem was that the oscilloscopes they had were old HP and DuMonts and only had bandwidth to 100 kHz or so. Fine for audio signals, but they were unable to see the 1 megaHz parasitic oscillations that the amps had. The mods I have for the circuit on the model IV were worked out by some engineers at Fisher. Since the Fisher guys worked on tuners, they had high frequency scopes and could see the parasitic oscillations and fix the problem.
The Acoustechs had good, big power transformers, but because of the era, they lacked large power supply capacitors. Replacing the old phenolic cased Mallory caps with new caps in the 10,000 uF range makes a huge difference in the bass. I used a model I chassis for it's nice heat sinks and huge transformer for a project amp that cranked out some 100 W/ch into 4 ohms and over 200 Watts bridged into 8 ohms, with over 300 Watts dynamic power. A very nice tranny.
Jerry
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Follow Ups
- Re: ACUSTECH AMP KLH MODEL 15 TUNER - Bold Eagle 10:11:12 01/01/04 (1)
- Re: ACUSTECH AMP KLH MODEL 15 TUNER - DENNIS FAWCETT 19:52:21 01/01/04 (0)
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