I have a Primaluna Prologue 3 which uses 5AR4 rectifier tubes which id like to roll. I’m looking at ShuGuang WE274B tubes which list as replacements for 5AR4 / 5U4G / 274B. However, the Primaluna manual lists compatible tubes as: GZ34, CV1377, 5V4G, 5T4, 5Y3 and Upscale Audio also list the Philips 5R4GYS.
All you will get with different rectifier tubes is a different voltage drop of the B+ voltage. And a corresponding change in voltages throughout the circuit. Use the rectifier that the circuit was designed with! A rectifier tube is NOT part of the music signal!
If the 5AR4 changes the sound of the preamp (assuming the originals are good) then you have bigger fish to fry. It should not make any difference at all- the difference between good 5AR4 and lessor examples is reliability. The power supply has to be designed well enough that the audio circuit is properly bypassed and the sawtooth waveform at the output of the rectifier is filtered out. If that has been done, then its expectation bias if you think you hear a difference.
OTOH, you will hear a difference from the tubes in the audio path- if you want to hear a nice improvement that's a far better place to put your dollars!
+1, on the Mullard (Blackburn plant) being the most reliable and longest lasting, GZ34/5AR4. You should most definitely contact Kevin Deal, at Upscale Audio, regarding whether a rectifier change will make an audible improvement, in your Primaluna gear. He has much experience with the brand. https://upscaleaudio.com/pages/contact-us
5AR4 and GZ34 are the same tube. I think that the Mullard is the best I have heard but the Matsushita made 5AR4s are actually very good. I am not a fan of substituting different tube types and would stick with the rectifier around which the circuit was designed.
However, the Primaluna manual lists compatible tubes as: GZ34, CV1377, 5V4G, 5T4, 5Y3 and Upscale Audio also list the Philips 5R4GYS.
My bad, I see now you are saying that the manual lists the above tubes as compatible IN ADDITION to the 5AR4.
I had read somewhere before what atmapshere is saying, that different but properly working rectifier tubes should not change the tone of a preamp, and I also believe the same for an amp, such as my Dynaco ST-70.
When I purchased my Mullard 5AR4 a number of years ago, they were reasonably priced, and they last forever and a day. Its one and done.
I have a "preferred series" (supposedly a "select" ShuGuang) 274b from thetubestore. Not sure if it improves the sound of my small single ended amp, but it sounds great and the tube simply looks cool so that makes me feel better about the whole thing.
If the voltage drop is different it can affect the sound. %AR4s tend to be about 50 volts with a light load. The unit will sound perkier with the higher voltage. You could have the unit set up with HEXFRED rectifiers and be done with the whole thing :)
not to be a killjoy in your case - but if you are going to tube roll to better the sound of the your system, do it with input tubes - spending $ to roll rectifiers are barking up the wrong tree
@jjss49 I did! replacing the OEM 12AX7/12AU7 with Gold Lion. But I fell down the rectifier rabbit hole when I read about the Philips 5R4GYS. Ima sucker for aesthetics...the WE274B is sexy piece of glass! I figured if I can improve sonics AND have some cool looking glass then why not?
Ima sucker for aesthetics...the WE274B is sexy piece of glass!
The two tubes have the same pin base with similar voltage limits and current specs, so you can interchange them and see how it goes. What is less obvious is the voltage drop you will see between the two- since the specs are very similar I suspect there will be only a minor difference between them.
You could also use a 5U4 which has the same pin base, but 5U4s have a greater voltage drop, and the 5AR4 was designed to have a controlled warmup time so as to allow the audio tubes (in particular, power tubes) time to warm up to prevent a phenomena called 'cathode stripping' which really does not occur with signal tubes as seen in a preamp circuit. The 5U4 warms up almost instantly. I've no experience with the WE tube. I'm saying that if looks are important, the ST-7 envelope used by the WE tube is also used by the 5U4. But I suspect you will find the 5U4 to sound a bit 'sleepy' due to the higher voltage drop across it, but they are so cheap you might get a pair and see what you think.
This is a quote from a recent review in TAS on the PrimaLuna EVO400 Preamp:
"To my mind, the 5AR4 tube rectifiers were at least partly responsible for the preamp’s tonal integrity, fleshing out the lower octaves and, in particular, infusing upright bass and cello with a full complement of tonal heft."
"To my mind, the 5AR4 tube rectifiers were at least partly
responsible for the preamp’s tonal integrity, fleshing out the lower
octaves and, in particular, infusing upright bass and cello with a full
complement of tonal heft."
That's a bit of a sketchy claim. Its far more likely that the audio circuit itself is responsible for this. A tube preamp can easily do exactly the same thing with solid state rectifiers (for example, by using 6SN7s in the line stage). Seriously, solid state rectifiers are now good enough that they easily keep up with tube rectifiers in terms of noise, but they don't have the voltage drop (which varies with current draw) that tube rectifiers do. Its for this latter reason that tube rectifiers are preferred in tube guitar amps, since that can impart that 'blues' sound which is really the sound of an amp that has a sagging power supply.
If you were to measure the voltage drop across the rectifier, you would find that the best sounding ones for hifi are also the ones that have the lowest voltage drop. There's nothing magical here- they respond to physics just like everything else in audio. And again- the power supply has to be working properly in that the filter caps are good and sufficient to properly bypass the supply and prevent noise from getting into the audio circuit. It that bit is true, then the only way a tube rectifier can affect the sound is by the voltage it puts out. So it should follow that if you use modern solid state rectifiers, you can make it even better, and in practice that turns out to be true as well.
Ralph...
I think the world of you and have learned very much from you over the years.
I just posted what was written in the review. However, I have sold, (as a dealer) and owned, (personally), quite a few preamps that have had tube rectified power supplies. I have found without question, that I could change the sound by replacing the tube rectifier. If this indeed due to a voltage increase or decrease, so be it, but it did and does change the sound.
If this indeed due to a voltage increase or decrease, so be it, but it did and does change the sound.
I'm sure it does! But that is the only reason they make a difference- and if its all about getting the best sound, you can do better than that by going solid state (and making sure that the circuit and power transformer are happy with the increased current draw) as long as the rectifier/transformer combo doesn't make noise- if it does, there are way of shutting it up.
Every time you think you've surpassed the penultimate, it turns out not to be the case- there's *always* a next step.
I have my 3 favorite recording’s that are superb at demonstrating vocals, soundstage and separation. They also do the magic act and make the KEF Q150’s disappear...if I can’t hear a difference then I’ll chalk up the 5R4GYS to pure aesthetics. 🤷🏼♂️ norah jones: little room roger waters: what God wants chris jones: when your gone
Just save yourself a bunch of time and grief by contacting Andy Bowman at Vintage Tube Service to get specific guidance. I only deal with Andy on my tube purchases and he knows what he is doing at a fair price.
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