What is the best sounding GZ34 / 5AR4 rectifier tube you've ever heard?

The best 5AR4 is the brown bottom Mullard made in the UK. I had one on a Modwright SWL 9.0 Signature edition Pre amp.

Matt M

Thought I remember reading a rectifier tube /rolling, wasn't that consequencensial to SQ.

IME, rectifiers make a big difference in sound. I have a box full of various kinds of 5AR4s (including various Mullards) along with two SET amps and a phono stage that use them. Believe me, they do sound different. My fav 5AR4/GZ34 is the Amperex brown base f33 from 1960. They’re often labeled "Made In Holland" but the L in the date code actually designates Brussels. In my all gear, they are similar in sound to Mullards but more open, and just as reliable. YMMV, natch. When I started buying this tube in 1999 it was $58 NOS. Now it’s $200 or so, just like the Blackburn Mullards. Fortunately, I have enough to last until I croak.

I’ll add that a fantastic tube is the KR Audio Riccardo Kron Anniversary Special Edition 5U4G. It can often but not always sub for a 5AR4. In my Allnic phono stage it’s another world, far better than any 5AR4 or 5U4G I’ve tried, including the vaunted Cossor CV575 from the early ’50s.

dutch or uk made real deal old stock gz34’s are best sounding and most reliable, close second are japan-made ones from the late 80’s and early 90’s made on old mullard tooling moved there, these are usually branded matsushita or national, then usa old stock ’big bottles’ are also quite good

how a rectifier will sound, how it will vary in sound, depends greatly on the circuit/item in which it is used, to say they make no difference sonically as a blanket statement is wrong

i have had various tube gear using these tubes since the late 80’s, and still have quite a collection of these

It depends on the system (as a whole) and your personal preference.

I have various Mullard/Blackburn), Amperex/Holland, later 2003-2004 (when they momentarily remedied the reliably issues) Sovtek as well as a few manufactured in Japan.

They all sounded good (to me) depending upon the gear/system I used them in and my favorite varied with each/different setup.

Reliability seems to be an issue with contemporary products, but I've mainly read about this in guitar audio forums.

Never owned a DH/SET amp that was tube rectified and have used them in vintage Pilot and Dynaco PP amps as well as Fender Princeton/Deluxe and Super Reverb guitar amps.

As an example, when I ran early production (fat sounding) Mullard EL84's in the the Pilot (232/240) amps I preferred the slightly lighter sound of the Sovtek and Japanese tubes.

If I used old production EI EL84's (lighter sounding than the Mullard's) I preferred the slightly richer sound of he Mullard/Amperex 5AR4's.

In my Dynaco (ST-70/MkIV) gear, which always ran Mullard XF1/XF2 EL34's, I preferred the slightly more detailed Amperex over the Mullard version in the ST-70's and the Mullard in the MkIV's.

I've forgotten the model/version codes on the old production Amperex/Mullard 5AR4's (recall 31/32 maybe), but can tell the earlier versions by looking at the plate construction (welded VS crimped tab construction).

This said both types sounded good/close.

Many say the metal base Amperex version is the holy grail, but I've only heard them in unfamiliar (to me) systems both HiFi and guitar/amp based - so no opinion on that.

Sorry if this does not answer your question.

DeKay