This rare Lafayette LA-310 / KA-310 is a beautiful vintage tube amplifier in both appearance and sound. The circuit and quality of parts are on par with other excellent 6BQ5/7189 based amplifiers of the day such as the Dynaco ST-35 or the Pilot 232.The power output is probably in the 18-20wpc range based on the higher than usual plate voltage found in this amp. The plates are at about 440v and the screens at about 360v. I will include a copy of the schematic with the amp. This is a fixed bias amplifier that in factory form did not provide a way to adjust the bias. I have added a bias pot (see photo) which allows for a much larger range of tubes that will run optimally in this circuit. Matched quads are a must since there is only one bias adjustment. I have also installed bias test points on the top of the chassis (see photo). No holes were drilled for this purpose, the holes were already present as heat vents. The procedure is simply to put the negative probe to the chassis and the positive probe in the tip jack next to each tube. You will get a mv reading across a 10 ohm resistor in the cathode circuit of each tube. There is also a red tip jack to check the B+ so it will be easy to calculate the power flowing through each tube. There are a few small scuffs on the paint, particularly on the bottom panel and immediately under the volume control on the right hand side, but overall this has survived the years quite well. This is a rare amplifier in very nice condition. You may not see another one like this for a long time. The B+ and bias supplies have been completely rebuilt and it is ready for long term service. You won't regret buying this one.
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