Has anyone else tried a Mullard GZ33 rectifier? I'm interested in your experience.

I guess I hadn't spent enough money on tubes lately and have been looking (in vain) for a reasonably priced backup fat base smooth plate GZ34 when I decided to take a chance on the GZ33. Technically it is essentially a higher current version of the GZ34. My pair arrived today and I've got to say they really sound fantastic. Images are big and tactile, the sound stage is huge and the overall tonality is rich and maybe even dense (as Will might say) but still fast, detailed and extended. At least as good as my fat base smooth plate GZ34s.

These tubes aren't cheap, but they are considerably less than any of the heritage GZ34s and I'd recommend anyone who is lusting after a fancy GZ34 but is unwilling to pay that kind of money consider the GZ33 instead. Of course this is JMO, FWIW, YMMV.

Turns out I have a pair of  EL33s and a gz37. The latter was pretty good in my DAC but not as good as others.  I’m holding on to it to try in my Decware preamp once I get off the waitlist sometime next fall. The EL33 power tubes in the DAC, working through the ZMA, transformed my listening room into a smoky bar room. The most warm and “tubie” sound off all the tubes that I tried, though really too much and lacking in detail and airiness in the upper frequencies. Still enjoyable for a few less well recorded songs I enjoy but don’t normally prefer to listen to using the ZMA.  Happy New Year!

Jon

I bought a few Mullard GZ33's from Billington export ltd.

In my UFO2.1, it flashed/sparked 2-3 times on start up, then it went through discoloration, sort of turned brownish, definitely far from clear/transparent glass prior to play time. I think it had about an hour - not more than two - of play time.

Would that be normal/expected or is that a sign of early failure? I bought 3 pieces, so if need be I can send pics of how the nib NOS looks like compared to this shortly used one.

Other than that it sounded good, but the most noticeable thing was that bass seemed a bit boomy. It could be a bad input tube matching? I used the french mullard RT e188cc/7308.

I know I ask a lot of questions, but what input tube could/should be a good match for the GZ33's?

Alright, thanks for the advice. I guess I'll write back in order to get the replacement.

My understanding is that maximum allowed capacitor value after the tube far exceeds the value that's in the UFO, and that no adapters are needed to run them. So I wasn't expecting any issues.

I also got a Ken-Rad hanging filament 5U4G and a 5Z3 Brimar hanging filament to play with, but I expect to settle with the GZ33 in case this was just a single defective/damaged tube

Based on some notes I gathered from this place, people usually recommend the 7308 with the GZ32/34 family, assumed the French Mullard 7308 should be a good match for GZ33 as well. So I still have hopes that bass being loose is the result of the tube being defective, will have to give it another run with another GZ33.

I was wondering if anyone had tried the WE 396A with the GZ33? Or the Tesla 6CC42 or something alike.

Just to add another experience, I have been using the Mullard GZ33 and Sohpia 274B in my amp, going back and forth over time, and I like them both.  I have had no problems with the GZ33, and I too, got it from
Billington.