5AR4/GZ34/U77 - Genalex Gold Lion

My 5U4C tube begin failing the other day in my little 5W audio tube amplifier. I had a spare in the wings, so I dropped that in, and everything worked again. With the old tube failing, I had noticed a subtle, but eventually pronounced change in audio quality. Eventually the quality turned catastrophically bad, so when I swapped the tube out for the replacement, I was really surprised to hear the difference. The sound stage was fuller and audio louder. I then thought, I wonder if there are better quality tubes out there. This was a generic Russian NOS tube. I have no idea what the manufacturer is. I was pretty cheap.After some research, for this amp, I learned I could swap it out with a 5AR4. The 5AR4 draws 2A as opposed to the 3A the 5U4C drew. Going down in amperage is acceptable, so I knew the amp could take it. I spent some time researching the tube brands and read many reviews. I settled on the Genalex Gold Lion.I just rolled the tube to this new Gold Lion and immediately heard the difference. It's subtle, but at the same time quite noticeable. The low end of the NOS tube had a slight "blurred" quality to the detail. This Gold Lion tube produces a very pleasing, clear, and balanced low end that's matched well with the upper frequencies. The high end of the NOS tube was a little scratchy and unbalanced with the low end. Wow... It breathed new life into this little amplifier.I've read about "break-in periods" for these tubes, although I've worked around RF engineers who are quite educated on tubes in general. They've told me, through furrowed brow, that tubes shouldn't exhibit any break-in characteristics. I'm sure this is quite controversial. The good news is, if there is a break-in period, I certainly haven't hit it yet, and the tube sounds fantastic right out of the box! If this break-in period exists, I can only expect the tube to sound better over time.

I recently purchased a Muzishare X7 integrated amp, which came stock with a Sovtek 5AR4 rectifier. Knowing that the Sovtek 5AR4's are not especially well-regarded, after owning the amp for a few weeks, I did some online research and purchased a Gold Lion. For the record, before swapping the rectifier, I had already upgraded the rest of the stock Muzishare-labeled tubes to Gold Lion KT88s, Sylvania 12AU7s, and a '58 RCA 12AX7.The difference vs. the Sovtek is not subtle, with improvements in every area - resolution, imaging vividness, midrange lushness, etc. etc. All of the usual audiophile good stuff is in abundance.Of particular note, bass is fuller but very controlled, and snare hits have a much more dynamic crack.For about $50, the Gold Lion rectifier is a very worthwhile upgrade over a Sovtek.

I received this tube yesterday and played it for about an hour in my old more-or-less stock Dynaco ST-70. A tad harsh in the highs at first, but seemed to open up just in that short time. Especially fine and tubey-sounding right out of the box playing Patsy Cline with the Jordanaires. Ditto other female voices.The bias on my outut tubes stayed much more stable than with my old rectifier tube. I'm running my Svetlana "winged C" EL34 output tubes at ~1.25 volts of bias now as per the advice of Bob Latino at The Dynaco Tube Audio Forum instead of the 1.56 volts as specified on the face of the amp. No loss of musicality as a result as far as I could tell.Kinda expensive for one tube, but I think it'll prove itself well worth it.

I’ve been using this tube in my vintage HiFi amps. It sounds great in everything I’ve put it in and the DC voltage is spot on. A lot less money than the vintage rectifier tubes so I’m hoping they’ll last for many hundreds of listening hours. Amps don’t seem to run any warmer than when using vintage rectifiers. Dynaco ST70, HH Scott 299C, and a Harman Kardon Ballad.

Absolutely beautiful tube. Puts my tube to shame.

plastic base got very hot 170 F, my NOS USA GX34 tubes measured only 120 F at base, returned item for credit, seller was very accommodating with fast credit.

Gold Lion rectifiers from Tubedepot are the real deal not some knock off. Buy with confidence they sound good and have good longevity.

I'm using this in a SET 300B amp. I like the sound a lot, more detailed than other tubes.