This is hi quality bass guitar amplifier with output TV sweep tubes PL500 PL504 27GB5 EL500 EL504 6GW6 6P36S 6P41S 6GB5 push pull class AB2

Ua=250V, Ug1=-45V, AB2, Raa = 3k

Frequency range: 30Hz-15kHz @ Po=30W continious, 0.5dB

Distortion: 40Hz 1.4%, 1kHZ 0.8%, 10kHz 1.7% for full continious power 30W:

Hum and noise: -67dB

Intermodulation: less then 1% at full continious power 25W

Max output power: 60W, 10%

PL504 push pull amplifier schematicsEL500 EL504 push pull amplifier schematics6GB5 bass guitar EL500 push pull amplifier diagram

These sweep TV tubes (line deflection valves) are still available in big quantaties and it’s easy to find them for reasnable prices, keep in mind that all of them are NOS and they were intended to be used in color TV sets in almost 24/7 operation cycle for many years, and every manufacturer gave guarantee for TV set and tubes too!!! It makes big difference to all Soviet and Chinese current production 6L6 and EL34 / 6CA7 valves which can’t last long in “heavy duty” devices

I have tried different tubes in this amplifier, the best results are with tubes of some of reputable manufacturers like Philips and Telefunken. EI, Tesla, Telam and Tungsram work great too! I’ve also rebuilt one Telewatt VS71 with 4 x Telefunken’s EL500 and 2 x ECF80 on new chassis and all  European EL500 sound superrior to Russian 6P36S clone.


This Post Has One Comment

  1. Karel

    Hi, I like the article you have published. The PSU and output transformer details are quite blurred. Can you email me a higher resolution copy?
    It would be much appreciated

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