Friedman Smallbox Bias: Is 10-11ma too far apart?

L

Luke Gibson

New member
Last night I measured the output tube Bias with my Compu-Bias and found the EL-34's are 10 to 11ma apart. The one tube was noticeably hotter as I removed the tubes from the probes. I realize back in the day no one even considered "matched" tubes. I think it sounds ok, but I've only had the amp a week or two....

Is this ok?

Should I order another set of tubes that are more closely matched?

Tubes are labeled ARS and 40 is written on top of each tube.


Input Voltage = 120Vac (Set with Variac)
Plate Voltage = 470Vdc
Cathode Current = 32ma & 43ma

Thanks in advance!!!
 
It's not ideal, but it won't necessarily hurt anything. The only issue I have run into with an impedance issue is hum.
 
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