Preamp Deal of the Century

PS cap replacement - anyone tried any other options - I have done the V caps and they were definitley an improvement so I am keen on upgrading power supply ( alps RK50 pot was also very good but pricy ) - another tweak I recomend is replacing the bottom plate in both pre and PS with something more rigid and using proprietry footers - I used symonite sandwich panel ( like alucabond ) - I drilled new vent holes of course

Cheers

Experiences with GZ33 vs GZ34? I'm looking for anyone who has compared and contrasted these two rectifier tubes in a Supratek preamp. The GZ33 is very cool looking, but how does it sound versus the GZ34/5AR4?

I've had numerous rectifiers in my sauvignon and cabernet. They include the 6106, Sylvannia 5a45, Mullard GZ33, Mullard GZ37, and the Mullard/Amperex metal-base GZ34. The Mullard/Amperex metal-base GZ34 is by far the best in my preamp. The improvements have been in the areas of reduced noise, longer note sustain/decay and to a lesser degree better harmonics which has increased the timbre. I've had my GZ34 in the system for about 5 years and my system is always powered on and playing.

From what I recall about the GZ33 and GZ37 specs the heater current is a good deal more than the GZ34. I think that anyone rolling regulators or rectifiers in the suprateks should consider the impact of one upon the other. Some of the larger regulator tubes place their own demand upon the power supply.

Well, I think my GE 5AR4 with the copper sides on the plates sounds great, but I just bought a Mullard GZ33 on e-pay, and I'll try it out when it arrives. If it doesn't sound as good as the GE, I'll take it out. I'm not running 6SN7s anymore, I'm using the 2C22 single triode, so I've reduced the demand on the power supply already - I guess I'll find out what the GZ33 sounds like soon enough...

So, I tried the Mullard GZ33 tonight, and I like it a lot! I bought a pair, and both had good getter flashing, full lettering, and tested 100%+ on my tube tester (set to 5V4, 5U4 and 5AR4 settings). Compared to the GE 5AR4, the background is cleaner, the soundstage is more focused (I can tell more easily where the instruments are) and the bass is a bit tighter and deeper. Cymbals are cleaner and have more focus. I swapped the two tubes back and forth twice each (I didn't want to stress the preamp with too many rapid on/off cycles). It just sounded more powerful and focused with the GZ33 than the GE 5AR4 - I'm keeping it in.

So my current optimum combo is:

Mullard GZ33 rectifier
Sovtek KT-66 regulator
Ken-Rad 2C22/7193 output tube (sub for 6SN7)
Solen PP Caps (33uF and 100uF, 630V) for power supply

It sounds incredible, IMHO.