Subbing in a 5Y3 Rectifier...

[Bob M.]

I have an amp that uses a 5AR4A/GZ34 rectifier tube. This amp is really loud and clean, using 2x 6L6s. As an experiment, I subbed in a 5Y3 rectifier tube (and, of course, I re-adjusted the bias). The amp 'gave it up' alot sooner on the volume and really, IMHO, improved the tone greatly and gave me the right amount of clean/dirty at a far lower volume. This amp was really too clean before.

The power tube plate voltage is about 460 Vdc. There are just a couple of preamp tubes and no reverb or tremolo. Are there any considerations I should be aware of for continued safe use of this 5Y3 rectifier tube?

Thanks,

Bob M.

[ThermionicScott]

I have an amp that uses a 5AR4A/GZ34 rectifier tube. This amp is really loud and clean, using 2x 6L6s. As an experiment, I subbed in a 5Y3 rectifier tube (and, of course, I re-adjusted the bias). The amp 'gave it up' alot sooner on the volume and really, IMHO, improved the tone greatly and gave me the right amount of clean/dirty at a far lower volume. This amp was really too clean before.

The power tube plate voltage is about 460 Vdc. There are just a couple of preamp tubes and no reverb or tremolo. Are there any considerations I should be aware of for continued safe use of this 5Y3 rectifier tube?

Thanks,

Bob M.

The current draw of the 6L6's may shorten the life of the 5Y3, but 5Y3s are so plentiful, I'd see how long it lasts you. You didn't say what amp you own, but the first filter capacitor is probably being spec for a 5Y3 too.

- Scott

[Bruce / Mission Amps]

I have an amp that uses a 5AR4A/GZ34 rectifier tube. This amp is really loud and clean, using 2x 6L6s. As an experiment, I subbed in a 5Y3 rectifier tube (and, of course, I re-adjusted the bias). The amp 'gave it up' alot sooner on the volume and really, IMHO, improved the tone greatly and gave me the right amount of clean/dirty at a far lower volume. This amp was really too clean before.

The power tube plate voltage is about 460 Vdc. There are just a couple of preamp tubes and no reverb or tremolo. Are there any considerations I should be aware of for continued safe use of this 5Y3 rectifier tube?

Thanks,

Bob M.

Or, use a 5R4 instead.
You can put a 47ohm 2watt resistor on the wire from lug 8 to the B+ rail and then don't worry about the first filter cap being too big.

[Groover]

So doing this in a BF Princeton circuit would be ok, with the two 6V6s? What is the next step "down" from a 5Y3?

[ThermionicScott]

So doing this in a BF Princeton circuit would be ok, with the two 6V6s? What is the next step "down" from a 5Y3?

Disconnecting one of the plates? I'm not aware of any less-capable 5V rectifier tube, since the 80/5Y3 was the first.

[Bob M.]

The first filter cap is normally what an amp designed around a 5Y3 rectifier would see anyway. Bruce, thanks for the tip on the 5R4 usage, a good way around it's limitations. Unfortunately. I didn't have a 5R4 lying around for my experiment but I have tons of 5Y3 tubes. At 30 mA draw per power tube plus 2 dual triodes, I should be ok, I think. Thanks for the replies.

Bob M.

[Bruce / Mission Amps]

The first filter cap is normally what an amp designed around a 5Y3 rectifier would see anyway. Bruce, thanks for the tip on the 5R4 usage, a good way around it's limitations. Unfortunately. I didn't have a 5R4 lying around for my experiment but I have tons of 5Y3 tubes. At 30 mA draw per power tube plus 2 dual triodes, I should be ok, I think. Thanks for the replies.

Bob M.

Yes, I have seen many old off brand vintage amps with two preamp tubes and two 6L6s... all run with a 5Y3GT. Quite a strain on it when cranked up to rockin' dog levels, but they still work.

[Bob M.]

Yes, Bruce, this amp does the rockin' dog thing really well now. It's a harp player's trick to sub in the 5Y3 in certain circuits. I thought I'd try it out and was happily surprised how fantastic it made this particular amp sound. It's a good idea for studio where volume isn't as important as the right tone. I also designed a very simple but effective bias-tracking circuit (so I can use the stock rectifier, or the 5Y3, depending on the task at hand) and it just so happens I have an extra unused chassis hole very near the bias circuit. Things sometimes just work out that way!

Bob M.