SF vs BF princetons- particularly rectifier tubes [Archive]

claytushaywood

July 9th, 2012, 03:44 PM

as a long time large fender owner I always have avoided late 70's fender amps... well I do have a 135 watt twin that I do love in fact. But you know, the ultralinear thing is pretty much a clean beast and that's it.

so i've recently found out that the smaller fenders- deluxes and especially princetons hardly ever changed over the years- or didnt have as major of changes rather.

id really like a princeton- maybe a deluxe, but i have loved me some princetons recently. The thing that's getting me right now is my hatred of 5u4 rectifier tubes... or well my experience with them. I know i've played princetons with gz34s... and i probably played many with 5u4's and didnt really realize it.

maybe this is a more general question... I have a pro reverb that I've been experimenting with rectifier tubes in. The 5u4 gets me at the right voltage and has a great dirty sound- but it just has no low end punch at all- and barely any clean headroom. the gz34 is much more up my alley.

is that sound difference from the tube itself- or is it just because of the voltage differences?

I've seen princeton clones with gz34's too... if i get a princeton with a 5u4 could I try to sub a gz34 (if the filtering and tubes can handle the voltage of course-- well can 6v6's in a princeton reverb handle the voltage increase of a gz34 tube for the most part?)

I'm sure someone else has experienced these tonal differences i'm trying to talk about here. It's a pretty major difference in my pro- its huge actually. night and day tone. with a 5u4 it's got the headroom of a deluxe (maybe more) but the great dirt sound of a princeton- also a bit looser like the princeton. with the gz34 it's tight and focused and has a LOT more headroom- much more like a twin

So i know you're not usually supposed to go from gz34 to 5u4-- but you can go from 5u4 to gz34 as long as the tubes and caps can handle it right? anyone experiment with this stuff with a princeton?

sorry for the long post!

Wally

July 9th, 2012, 05:35 PM

A GZ34/5AR4 rectifier will stress the PT less than a 5U4 with regards to current draw. IF all else in the circuit 'allows' the change in voltage, then one can use a GZ34 in the spot that a 5U4 occupies.
I also have to note that ime and imho 'blind' comparisons of sonic differences in amps when 'comparing' these two rectifiers is not a valid exercise. One must take note of voltages and biasing. I am not saying there isn't a difference; but without knowing what is going on in the circuit, it is not a valid comparison, imho. IF one biases the two situations to the same point of plate dissipation, then I consider the comparison to be more useful.
When simply plugging and playing, the two tubes yield two very differently bias points/plate dissipation results...and therefore the sonic results are very different. ONE difference between the Pro REverb and the 6V6 amps liekthe DR or the PRinceton REverb is that as with all tubes there is a limit on what voltages a 6V6 can handle...and that limit is quite a bit below what a 6L6 will stand. There was a time in the '90's when there were no new production tubes that would stand up in a Deluxe REverb.....and we used 6L6's to get by unless we wanted to pay for NOS 6V6.s....and even then with modern wall voltages things were cutting close. New 6V6's are better prepared to deal with that situation, and JJ 6V6's have the ability to function at higher votlages than 'normal' 6V6's anyway. Some folks consider them to be low power 6L6's.
You ask..."is that sound difference from the tube itself- or is it just because of the voltage differences? That is a bit of a loaded question. The sound difference is directly influenced by the tube itself BECAUSE those two tubes yield different voltages. A rectifier tube is not a tone generating tube, but the voltage it supplies determines what is going to happen throughout the entire circuit.

FWIW, a good tech can make that SF PRo REverb of yours punch with the
5U4 in it. Someone who doesn't understand what is wanted or how to get it will be challenged to do that. That said, a GZ34 might make the amp punch even more in such an amp that was made to 'punch' with the 5U4....but you would want to make sure the bias was proper.


	Telecaster Guitar Forum > The DIY Channel > Shock Brother's DIY Amps > SF vs BF princetons- particularly rectifier tubes PDA SF vs BF princetons- particularly rectifier tubes claytushaywood July 9th, 2012, 03:44 PM as a long time large fender owner I always have avoided late 70's fender amps... well I do have a 135 watt twin that I do love in fact. But you know, the ultralinear thing is pretty much a clean beast and that's it. so i've recently found out that the smaller fenders- deluxes and especially princetons hardly ever changed over the years- or didnt have as major of changes rather. id really like a princeton- maybe a deluxe, but i have loved me some princetons recently. The thing that's getting me right now is my hatred of 5u4 rectifier tubes... or well my experience with them. I know i've played princetons with gz34s... and i probably played many with 5u4's and didnt really realize it. maybe this is a more general question... I have a pro reverb that I've been experimenting with rectifier tubes in. The 5u4 gets me at the right voltage and has a great dirty sound- but it just has no low end punch at all- and barely any clean headroom. the gz34 is much more up my alley. is that sound difference from the tube itself- or is it just because of the voltage differences? I've seen princeton clones with gz34's too... if i get a princeton with a 5u4 could I try to sub a gz34 (if the filtering and tubes can handle the voltage of course-- well can 6v6's in a princeton reverb handle the voltage increase of a gz34 tube for the most part?) I'm sure someone else has experienced these tonal differences i'm trying to talk about here. It's a pretty major difference in my pro- its huge actually. night and day tone. with a 5u4 it's got the headroom of a deluxe (maybe more) but the great dirt sound of a princeton- also a bit looser like the princeton. with the gz34 it's tight and focused and has a LOT more headroom- much more like a twin So i know you're not usually supposed to go from gz34 to 5u4-- but you can go from 5u4 to gz34 as long as the tubes and caps can handle it right? anyone experiment with this stuff with a princeton? sorry for the long post! Wally July 9th, 2012, 05:35 PM A GZ34/5AR4 rectifier will stress the PT less than a 5U4 with regards to current draw. IF all else in the circuit 'allows' the change in voltage, then one can use a GZ34 in the spot that a 5U4 occupies. I also have to note that ime and imho 'blind' comparisons of sonic differences in amps when 'comparing' these two rectifiers is not a valid exercise. One must take note of voltages and biasing. I am not saying there isn't a difference; but without knowing what is going on in the circuit, it is not a valid comparison, imho. IF one biases the two situations to the same point of plate dissipation, then I consider the comparison to be more useful. When simply plugging and playing, the two tubes yield two very differently bias points/plate dissipation results...and therefore the sonic results are very different. ONE difference between the Pro REverb and the 6V6 amps liekthe DR or the PRinceton REverb is that as with all tubes there is a limit on what voltages a 6V6 can handle...and that limit is quite a bit below what a 6L6 will stand. There was a time in the '90's when there were no new production tubes that would stand up in a Deluxe REverb.....and we used 6L6's to get by unless we wanted to pay for NOS 6V6.s....and even then with modern wall voltages things were cutting close. New 6V6's are better prepared to deal with that situation, and JJ 6V6's have the ability to function at higher votlages than 'normal' 6V6's anyway. Some folks consider them to be low power 6L6's. You ask..."is that sound difference from the tube itself- or is it just because of the voltage differences? That is a bit of a loaded question. The sound difference is directly influenced by the tube itself BECAUSE those two tubes yield different voltages. A rectifier tube is not a tone generating tube, but the voltage it supplies determines what is going to happen throughout the entire circuit. FWIW, a good tech can make that SF PRo REverb of yours punch with the 5U4 in it. Someone who doesn't understand what is wanted or how to get it will be challenged to do that. That said, a GZ34 might make the amp punch even more in such an amp that was made to 'punch' with the 5U4....but you would want to make sure the bias was proper.