I've read a few different posts and articles regarding the bias in the original 5E3 design, and that it tends to be on the hot side for most 6V6s. So I thought I'd measure mine. My 5E3 has stock values in the circuit components (with little variation anyway - a 270 ohm power tube cathode resistor instead of 250 ohm).
I have 3 different 5Y3GT tubes that I tried:
I have 3 different pairs of 6V6s that I tried against each of these 5Y3 tubes:
Here's what I measured for plate power (at idle):
So what's up with this new Sovtek 5Y3? Do they all run "hotter" than other brands? Or do NOS 5Y3's generally run "cooler" than new 5Y3's (the Sovtek is the only new 5Y3 I have to check)? Or does it just simply vary tube to tube and you have to check each time?
Seems like in any case, these tubes are being pushed pretty hard. Should I be trying to find a way to bring down the plate voltage?
I have 3 different 5Y3GT tubes that I tried:
- Ken Rad (USA)
- Sovtek (new - USSR)
- Tung-Sol (USA)
I have 3 different pairs of 6V6s that I tried against each of these 5Y3 tubes:
- JJ (new)
- Tung-Sol (new - USSR)
- Phillips (vintage)
Here's what I measured for plate power (at idle):
- With Sovtek 5Y3, JJs ran about 17.8 watts (plate voltages around 403V)
- With Sovtek 5Y3, the other 6V6s ran about 17.2-17.5 watts (plate voltages around 408V)
- With the non-Sovtek 5Y3s, JJs ran about 14.0-14.4 watts (plate voltages around 363V)
- With the non-Sovtek 5Y3s, the other 6V6s ran about 13.8-14.0 watts (plate voltages around 365V)
So what's up with this new Sovtek 5Y3? Do they all run "hotter" than other brands? Or do NOS 5Y3's generally run "cooler" than new 5Y3's (the Sovtek is the only new 5Y3 I have to check)? Or does it just simply vary tube to tube and you have to check each time?
Seems like in any case, these tubes are being pushed pretty hard. Should I be trying to find a way to bring down the plate voltage?
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