thread: Hiwatt
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Old 11th April 2019
Lives for gear
ponzi's Avatar

Originally Posted by John Eppstein View Post
They were also notably unreliable and contained transistor pairs that had to be hand matched and thermally coupled together to keep the amp from blowing up like a big firecracker.

They also didn't really sound very good and were quite unpopular.
I had one for a time and I thought it put out a stonking good sound. The one I possessed had been serviced and one of the output transistors was replaced. The unit did not appear to have been blown up like a firecracker when this device failed. The output transistors were a complementary NPN-PNP combination. I do not recall any special thermal coupling aside from the fact, that like all transistor power amps, they were mounted on a heat sink. In this case, the heat sink formed the entire back of the chassis.

I also believe it was mid to late 1970s in production. I purchased mine used in 1976.

Hope I am not repeating myself, but unlike any other SS amp I have seen, it had an output transformer coupling the transistors to the speaker jacks, allowing it to drive higher impedence loads. I believe this gave it a nicer distortion sound. I also thing it was cute given the case design.

On the negative side, it threw a large magnetic field that single coil pickups loved to receive, giving lots of 60 cycle hum at large volumes. Also, the tiny gain slider switches were fiddly and did not always retain their settings. And I learned only in the last few years that it had a higher gain setting only available through the use of a plug in pedal. So, almost an early multiple channel implementation.

Since it had both a power and output transformer, it was every bit as heavy as its tube counterparts. I do have the impression it did not sell very well, as I don't ever recall seeing one in a music store, nor did I know anyone else who had one, nor see one on the stage of any band performance.