L-50, Amplifier

Read more on the Linear L-50 in our home audio section

Alex Dutton2006-11-18 17:58

I have recenlty been given a Linear L50 valve amplifier to restore and repair, that was saved from a rubish skip. It has a valve line up of two EF86 pre-amp valves, an ECC83 driver, two EL34 power valves and a GZ34 rectifier. Inside the chassis are two circuit boards. I have had sound out of the amp accompanied with lots of hum which is not regulated by the volume controlls. I therefore feel that there is an im-balance in the bias current or inadequate power supply smoothing. However, the power valve wiring does not look conventional and the circuit boards are really untidy. I am therefore looking for a circuit diagram, if anyone could help me out here. Many thanks.


Alex Dutton2006-11-18 17:58

Snap! Well not quite. I am in the process of repairing a similar amp. The one I have is in quite good condition. Everything appears original apart from capacitors that have been added to the rectifier circuitry. And yes this one hums like a pig too. If you can forward me your email addy I can send you detailed photos for cross reference purposes.

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