Genalex - GZ34 / U77

4 Reviews

Availability: Usually ships within 24 hours.

USD $‎65.95
The Genalex Gold Lion GZ34 / U77 is smooth, refined, and balanced for the very best high-end audio sound. This GZ34 (5AR4) tube is robust and works great in many different guitar amps such as Vox and Fender amps, but also vintage hifi like Dynaco and Scott.

GZ34 and U77 is the European name for the 5AR4 and is compatible with any circuit using a 5AR4 tube.

Other Genalex - Gold Lion tubes5AR4 Tube Types

Additional Information and Downloads

Genalex - Gold Lion GZ34 / U77 Datasheet (PDF)

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Warranty Information and Return Policy

Warranty Period: 3 months

All our tubes are guaranteed for 3 months from the date of purchase. (Any exceptions will be noted on that tube's Warranty tab)

If you receive a tube that does not perform to the manufacturer's specifications, please do the following:

- contact us to get a return authorization
- return it via regular mail within 90 days from when we shipped it, and we will provide an exchange or refund of the full purchase price of the tube.

Returns not related to warranty or defect will be considered at our discretion, and are subject to a 15% restocking fee.

We can not accept returns that don't have an authorization, are past 3 month, or are returned improperly.

These guidelines may be updated without notice.

Ratings & Reviews

4 reviews

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Genalex - GZ34 / U77 | Worthy of a listen...

by -

I too, am using this in a Modwright LS100 preamp. I got tired of second mortgage priced NOS tubes for a rectifier so I gave this GL-GZ34 tube a try. I like it...a lot. I have depth, clarity, and something no other NOS tube has given me. Texture. When I listen, the instruments seem so much more real. Brass instruments seem to have more impact, strings more life, woodwinds have that "chesty, wooden" sense to them. The notes have an edge to them and are not rolled off , bass has impact.
Again, I really like mine and have no desire to put back my NOS tube. For the price to value ratio, five stars...

Genalex - GZ34 / U77 | Best non-NOS rectifier tube I’ve found


After having tried multiple modern production rectifier tubes, I’ve settled on these Genalex GL-GZ34 as being the cream of the crop. Highly recommended. Smooth, vintage feel.

Genalex - GZ34 / U77 | Hum = vibrations. Vibrations = bad.


I replaced the cheap Chinese tube that shipped with my st-120 with this Genalex GLGZ34 tube. I wasn’t sure changing the rectifier would improve the sound but it was much clearer. Very nice detail. The sound was a huge improvement over the old rectifier. Unfortunately after 90 days the tube itself started to produce an audible hum. Hum = vibrations. Vibrations = bad. I noticed when changing the tube it was not snug in the socket. The old one fits very snug as does the new Sovtek. I really wanted this tube to keep working. It was 5 stars for about 90 days.

A Nice Surprise


This tube replaces the stock Sovtek 5AR4 in my ModWright LS100. I'm only just beginning to appreciate the effect rectifiers have on sound quality. With this tube the sound is smoother and more relaxed. The sound stage is moved back somewhat. But the real surprise is that individual instruments seem to stand up when played and then sit down again when the player is done. This effect just adds more dimension and realism to high definition recordings. Can't comment yet on reliability, but the sound quality is a notable step up.