Reverb tanks impedance mismatching

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Cowasaki
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Reverb tanks impedance mismatching

Post by Cowasaki »

Question about impedance mismatched reverb tanks.

I have just built a reverb unit mainly from bits I had lying around. I had a couple of small reverb tanks with the codes 3WB2C1B & 8EB2C1B

I have built reverb circuits in Princeton Reverbs and fender reverb units but wanted to see what I could build with what I had.

Ok so I have used a modified version of the fender reverb circuit but using 12at7 and 12ax7 tubes. With the reverb transformer driven by a 12AT7 rather than the normal 6v6. I did this because I did not have 6v for the 6v6’s heater filaments. The reverb transformer is a standard fender clone so input impedance of 2500 and output of 8 ohms.

My tanks are both “C” so 200 ohms input impedance or 25x more than the output of the reverb transformer (8 ohms). It works but it’s not ideal also as it’s being driven from a 12AT7 rather than a 6v6 would that alter the input impedance to the transformer and from there change the output impedance of the transformer making the mismatch better or worse?

I will try it tomorrow with the reverb tank from one of the fenders but it does at least sound.
Guitar amplifier builder and avid electronics nut

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Cowasaki Audio
Hugo
Posts: 132
Joined: Sun Feb 28, 2021 10:20 am

Re: Reverb tanks impedance mismatching

Post by Hugo »

Perhaps you could run the 6V6 as a cathode follower and do away with the transformer.
Obviously a 12AT7 can not drive the springs well so in that case it is not the transformer.
I think the 6V6 with transformer will work but you do not need it.
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