no problem. at the risk of jinxing things this amperex is really doing the job well. sweet detail, never harsh or sibilant, good dynamics never over the top. the bass peak i heard when i first tried it has developed into a warmer sound signature.
Turns out my spare Mullard rectifiers are f32 and the one in my preamp is an f31, date code B0C, so Blackburn factory, March 1960. I tried the stock factory one but couldn't switch back quickly enough. Ok, that sounds dramatic, but it was just immediately clear that bass was lighter and less textured. Midrange was slightly recessed. Highs didn't seem to change much, but to be honest I only had it in for an hour. I popped in a stock PrimaLuna 5AR4 and it sounded better than stock, but not as good as the f31 Mullard. Silly, I put f31 back in before trying the newer f32, but I wanted my bliss back. Note that my f31 is not a metal base unit. Cheers, Robert
Is it the so-called "fat base"? That's the tube I started with in my phono stage power supply. From there, I started trying a bunch of different ones. I have a NIB metal base in right now-- it has more bass than the GEC u 52 but less finesse. I think it's all tradeoffs. I can't see myself swapping these out for tone control purposes- I guess I just need to settle in to the one that least compromises what I'm after. It's too bad some of these tubes have become unobtanium. They do make a difference. I guess if I had a piece of gear that sounded good with a modern production tube, I'd just leave it alone-- there's a world of tinkering to be had in audio, as you know, and I need less, not more to tinker with. I need something with one big red button that says "PLAY."
Good question, I don't have much experience with the rectifier and not done a lot of research. But I think it probably is, I did note the base as being a little thicker than typical. And the fat base apparently ran from 1958 to 1962, so mine being a 1960 I guess that it must be fat. I prefer the term husky. Lol. Cheers, Robert
So, after about a month? of listening using the Mullard branded metal base GZ34, I swapped it out for a GEC u52 (this one is I think earlier than my brown base version which was branded Brimar). It does not have the bass or slam of the metal base Mullard, but has believable mids and highs that are delicate-- it has a sort of finesse that I think the Mullard lacks. But it simply doesn't have the power of the Mullard. Perhaps it is because of the nature of the different tubes, voltage and the like. If anybody knows more about the history of the u52 I'd love to hear about it. For reading this, you get a cookie: (This is the power supply of my phono stage) IMG_1153 by William Hart, on Flickr
BTW I used to build custom guitar amplifiers. Used Sovtek 5AR4 and only one failed out of the few hundred amps I built. Lit up like a sparkler upon power up.
my sovtek failed after 4 months. recently put a new sovtek back in replacing the mullard, man what a downgrade.
Yes, as mentioned in my recent posts here, I have been playing with a NIB, NOS metal base GZ34. It is branded Mullard, made in Holland Philips.
My guess is that telling sound differences between rectifiers of different brands takes a resolving rig upstream. I recently got a British NOS Mullard to replace the stock 5AR4 (JJ Electronic) in my Japanese made TubeDepot Eclipse SET amp. I can certainly tell the difference. The rectifier itself changes sound quality indirectly but undoubtedly it does. My sense is that it provides sufficient clean power to make the other Eclipse NOS tubes and electronics perform at full potential. The upgrade resulted most noticeably in tighter bass, a velvety top end and a midrange that makes vocals sound glorious. The crowning touch is how congested musical passages, particularly in symphonic works, are handled. The volume can be raised to concert levels without clipping and instrument sections don't shout above one another. I would not recommend the investment, however, unless upstream gear is revealing. Component synergy is delicate. Take out a component or change the cabling and the loss of magic can to a lesser or greater extent be easily heard. There are many ways to build the synergy that makes the rectifier investment worthwhile. Mine starts with clean wall power produced by the PS Audio P15 regenerator. Power cables are AQ Thunder and NRG-Y2. My desktop rig consists of a PC USB signal fed into a Denafrips Iris DDC (USB pollution control), then to the Denafrips Pontus II ladder to ladder DAC via Is2 connection. The Pontus feeds the TubeDepot Eclipse SET amp driving Klipsch RP-160M bookshelf speakers. Interconnects are AQ Earth and Water and speaker cables are AQ Robin Hood Zeros. A couple of journey observations. I would not have invested in a $150 rectifier if I did not have a SET amp. Fans know the sound quality transformation that SET amps can provide can be downright magical. Magical can't be measured but it's said that it has to do with adding harmonic distortion of the good kind. You have to hear a well designed SET amp, not just to hear but to feel the difference from a push-pull tube amp or a SS amp. SET is old technology but it's simple and it's seen a resurgence with a greater supply of quality high sensitivity speakers. I also would not have invested in a good rectifier if the Klipsch speakers were not as surprisingly capable as they are. Audio club visitors are amazed that they don't exhibit any of the characteristics that have brought on criticism to Klipsch for decades. They are inexpensive but their excellent musical presentation has to be heard with good gear to be believed. To put it simply, the Mullard NOS rectifier raises the magic from a 6 with the stock rectifier to a 10. That has been my experience and I fully understand that it is not an experience that is easily replicated.
Just did a complete recycle of all of my rectifiers to see if the best sound was still tracking with the Mullard F32 GZ34 and my recent amp change. Here are the findings in my tube preamp from last to first: Gold Lion 5AR4. Decent pep, forward midrange, bland overall sound. Sovtek 5Ar4. Occasionally euphonic and sweet at its best, bloated, irritating peaky bass at its worst. Dynamics OK. Amperex late version NOS GZ34 labelled as Tektronix. Sounds very good, a step above the others. Early bass peak is gone, occasionally less than refined treble. Mullard GZ34 f32. The best by far, smooth, ultra dynamic, good balance and huge sound stage. I just ordered a rare 1957 Mullard Stittard Holland f30. Supposedly better than the f32. We'll see, one of the Mullards will be a spare if nothing else.
I’ve been using the Sovtek 5AR4 since I got my ModWright LS100. Is there a specific replacement that can be recommended for this particular preamp? It really sounds great to me now but wondering about the concerns over reliability.
I agree. Ive "had" a few :-/ Tungsols from the 60s are very good too, if you like the Mullards. Not much cheaper. There are other brands that were made in Blackburn by Mullard too. Have to look for them.
I agree with your assessment. Some RCAs are like the Amperex btw. you're going to love the 57 GZ34! How much did you pay for it, if you dont mind me asking.
My first Sovtek went out after 4 months and took fuses with it. Definitely look for a Mullard F31. Supposedly ultra long life. Some examples: 1 x Mullard GZ34/5AR4 Rectifier Tube*FAT BASE*Very Strong & Balanced*(2 Avail) | eBay MULLARD EARLY TYPE FAT BASE GZ34 / 5AR4 RECTIFIRE AUDIO TUBE / f31 B8E 1958 | eBay Mullard Fat-Base GZ34 5AR4 Rectifier Tube- Hickok 539B tests@ 162/160, Min:54/54 | eBay
In the world of rectifier tubes why are 5ar4/GZ34's more expensive than the others? Rarity or are they that much better than 5R4 or 5U4's ...etc ?
So, as far as New Production 5AR4 is the Sovtek it? Aren’t there any other decent New Production 5AR4 tubes being manufactured?
There are plenty of different brands but only a few factories making them 5AR4 Rectifier Tubes | Tube Depot . In my experience the new production rectifier tubes have a life span of months rather than decades like the NOS Mullards. The bigger problem is when the go they always take out fuses and often times other tubes. I read somewhere that the materials used in the old rectifier tubes are ultra toxic and completely unobtanium currently so there is little hope new production will ever even come close to the quality of the NOS Mullards.
the f32 Mullard is also excellent and blows away the new production tubes. GZ34 / 5AR4 tube VALVO / MULLARD - MILITARY - f32 - NOS - oo - 1962 | eBay 1x Mullard GZ34 (5AR4 ~5U4G ~U52 ~GZ37), f32, 4-Notch Plate, Philips Logo, 100% | eBay
