Gibson BR-9 Guitar Amplifier

I saw this on eBay and landed it for about $500. It had been stored unused for so long that the power cord crumbled to bits when I extended it. I replaced all the electrolytic capacitors and a couple of resistors that had drifted in value. The valves appeared to be all original.

Judging by the date stamp on the speaker, the amp is from around 1952. The 6-inch speaker doesn't have a permanent magnet on it but an electromagnet coil that is energised via the amplifiers power supply. This coil also doubles as the power supply filter choke.

The amplifier itself is vey simple with a single preamp stage based around a 6SJ7 pentode, followed by a pair of 6V6GT's in parallel, biased in Class-A. Yep, not push-pull. This delivers about 8W, although the speaker is very inefficient so it doesn't sound that loud. This amp gets rather crunchy when turned up full and that is how I prefer to play it. Like a lot of small amps of the period, it has a 5Y3 rectifier in the power supply.

This is the only vintage amp I own and also the one I paid the least for. This is surprising considering its age. I guess I was lucky.