Rectifiers for Princeton

[pchilson]

Hi,

I just picked up this '70 Princeton non-reverb. The tubes all appear to be stock RCAs throughout. The tube chart calls for a GZ34 rectifier but there is a 5U4GB installed. I've found some evidence that this could very well be the stock tube and it just not agreeing with the tube chart.

Whats the basic difference between these two rectifiers and is it likely that the 5U4GB was indeed stuck in there at the factory? I've also got some NOS 5V4Gas around here, would they work as well? I have no GZ34s.

What would you do?

[tubeswell]

5AR4/GZ34 can handle up to 60uF reservoir cap and drops about 30V off what a FW SS rectifier would deliver and delivers about 250mA output current - and requires a 2A 5V winding.

5U4GB can handle up to 40uF reservoir cap and drops about 60V off what a FW SS rectifier would deliver and delivers about 275mA output current (250mA for a Sovtek 5U4G) - and requires a 3A 5V winding.

5V4G is rated for about 4uF reservoir cap (but most of them can handle about 20uF without any problems) and AFAICT drops about 75V off what an SS rectifier would deliver, and delivers about 175mA output current - and requires a 2A 5V winding.

So (assuming the PT has a 3A 5V winding) a 5U4GB won't hurt the amp a bit and will run the B+ a bit lower than a GZ34

A 5V4 is the saggiest of these ones but you have to watch your reservoir capacitance.

A 5Y3GT is saggier still but only delivers about 125mA output current and drops 90V off what a SS rectifier would deliver. It will run off 40uF and supply 2 x 6V6s and 2 or 3 pre-amp tubes without giving up the ghost too soon (but is better with 20uF).

[pchilson]

5AR4/GZ34 can handle up to 60uF reservoir cap and drops about 30V off what a FW SS rectifier would deliver and delivers about 250mA output current - and requires a 2A 5V winding.

5U4GB can handle up to 40uF reservoir cap and drops about 60V off what a FW SS rectifier would deliver and delivers about 275mA output current (250mA for a Sovtek 5U4G) - and requires a 3A 5V winding.

5V4G is rated for about 4uF reservoir cap (but most of them can handle about 20uF without any problems) and AFAICT drops about 75V off what an SS rectifier would deliver, and delivers about 175mA output current - and requires a 2A 5V winding.

So (assuming the PT has a 3A 5V winding) a 5U4GB won't hurt the amp a bit and will run the B+ a bit lower than a GZ34

A 5V4 is the saggiest of these ones but you have to watch your reservoir capacitance.

A 5Y3GT is saggier still but only delivers about 125mA output current and drops 90V off what a SS rectifier would deliver. It will run off 40uF and supply 2 x 6V6s and 2 or 3 pre-amp tubes without giving up the ghost too soon (but is better with 20uF).

Good info. Thanks.

How would I know what the PT is rated for? This is stock Princeton stuff. There is some suggestion that Fender put the 5U4GB in these so would you assume the PT is rated to handle it or perhaps thats a bad bet?
I also have a Vibro Champ that uses the 5Y3GT that sees a 40uF from the factory. So I guess they didn't always stick to the spec sheets...

[Prairie Dawg]

Good info. Thanks.

How would I know what the PT is rated for? This is stock Princeton stuff. There is some suggestion that Fender put the 5U4GB in these so would you assume the PT is rated to handle it or perhaps thats a bad bet?
I also have a Vibro Champ that uses the 5Y3GT that sees a 40uF from the factory. So I guess they didn't always stick to the spec sheets...

If it was my choice I'd put in a 5R4. Does everything a 5U4 does and less current draw too. If you get one make sure it's not a Cetron potato masher, they take up a lotta room.