Rectifier tube
- Thread starter craigh
- Start date
The GZ34 is a replacement for the 5AR4 it's what I have in my ST70. The 5Y3S where used in early Fender guitar amps the plate voltage will probably drop.
I searched the web but can't fine good data on the 5Y3S if I had one I could measure it. So IMHO I wouldn't use it could damage the transformer.
I searched the web but can't fine good data on the 5Y3S if I had one I could measure it. So IMHO I wouldn't use it could damage the transformer.
Congratulations Craig. Tubes rule!!!!
Big Jim 007
New member
Re: Rectifier tube (St-70)
The only proper replacement or substitute is a 5UA4, you will lose some watts, about 5 to be exact, but the 5UA4 is a stout rectifier and will more than add make up for the 5 watts with more headroom and cleaner presentation IMHO. As noted, the 5Y3 doesn't allow for enough plate voltage and will harm the tranny's in the long run. The nice thing about the 5UA4 is that they're readily available and affordable even with choice NOS.
Jim
The only proper replacement or substitute is a 5UA4, you will lose some watts, about 5 to be exact, but the 5UA4 is a stout rectifier and will more than add make up for the 5 watts with more headroom and cleaner presentation IMHO. As noted, the 5Y3 doesn't allow for enough plate voltage and will harm the tranny's in the long run. The nice thing about the 5UA4 is that they're readily available and affordable even with choice NOS.
Jim
Cathode Ray
New member
The 5AR4/GZ34 is an indirectly heated rectifier with a 5 volt heater at 1.9A. The Mullard and GE are generally rated at 450V @ 250mA; modern Chinese won't handle that voltage or current for long. The Russian and Eastern European are better than the Chinese. The voltage drop by the rectifier is about 17V.
The 5Y3 is an indirectly heated rectifier with a 5V heater at 2A. They are rated for 350V @ 125mA. They won't last long in a ST70 which has a plate voltage of 435V and rectifier current of of almost 250mA.
The 5U4GB is a directly heated rectifier rated at 5V and 3A. They are rated for 275mA @ 450V with a voltage drop of about 35V. Since the Dynaco power transformer is only rated for 2A, this 3A rectifier will stress the power transformer, make it run hot, and eventually damage it. Triode Electronics sells an uprated power transformer that that can handle up to 4A for the rectifier; it is highly recommended. The 5V3A is an uprated 5U4GB that is well worth looking for if your equipment can use a 5U4GB
The 5AU4/5V3 are my favorite rectifiers; they are uprated 5U4GB that can handle more even current. They are rated for 350mA @ 450V with a voltage drop of about 35V. Notice: the 5AU4 and 5V3 have a current ratings of 3.8A, almost twice the current the ST70 transformer is rated for. These robust tubes were made for color television sets. I use them where I can, but definitely not in a ST70 unless the Triode Electronics power transformer is substituted for the original.
The 5R4GYB is a directly heated rectifier rated at 5V and 2A; so it will work fine in a ST70. It is rated at 250mA at 900V so will be coasting in the ST70. It drops about 40V so the plate voltage will be slightly less. Your power might be down a little: you might have a ST68.35.
tubemaze
New member
Hey Craig, as Cathode Ray said, 5Y3 is not a substitute for 5AR4 especially in Dynaco it might end up arcing and burning up components - too much stress for that little tube.
5R4G is a very nice alternative to 5AR4, but the sounds will become more relaxed and a bit warmer.
New sensor just release Genalex, Mullard and Tung-sol GZ34 tubes, which are fantastic alternatives to the NOS Mullard GZ34 tubes. Although bass is still not as punchy - the difference is very minimal.
5R4G is a very nice alternative to 5AR4, but the sounds will become more relaxed and a bit warmer.
New sensor just release Genalex, Mullard and Tung-sol GZ34 tubes, which are fantastic alternatives to the NOS Mullard GZ34 tubes. Although bass is still not as punchy - the difference is very minimal.
Wow...I barely understood that...but I would love to get your opinion on tubes here. Namely 6922, 7308, 6CA4 and 6X4. I use Mullards for 6922s...but am open minded to great, super quiet options. I was strongly recommended Tele 6922s. I love my current Amperex US PQ 7308. I just ordered 1950s square getter Mullards (6CA4) and Mullard 6X4 (also 1950s) from Brent Jessee...on the back of great performance from my earlier set I bought from him 3 years ago...at that time, I had 2 the 6CA4 Mullards and a Sylvania 6X4...curious to see what happens when its all Mullards across the board in the PSU. Anyway, thanks for any other recommendations!! (BTW, I use EAT tube dampers wherever I can.) Thanks for any recommendations!!
mep
Well-known member
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- Dec 4, 2013
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Lloyd- One thing you need to understand is that there are no guarantees with regards to noise from any 9 pin tube regardless of who made it. Telefunkens can be noisy, Mullards can be noisy, Amperex can be noisy and on and on. You have to buy tubes from people who can test and measure them for noise and grade them for the application they will be used for. Your life is made easier because you don't need tubes for a phono section. The bottom line is that there is no silver bullet. All tubes regardless of manufacturer are a crapshoot with regards to noise.
Cathode Ray
New member
The 6CA4 and 6X4 are low voltage and current rectifiers tubes and have little effect on the sound of a device and no noise issues. My advice is to buy several brands new in box and tested from a source like Jim McShane and see if you notice much difference. Antique Electric Supply (tubesandmore dot com) sells the JJ 6CA4 for $11.50 which is probably all the tube you will ever need. AES sells the 6X4 for $13.15. These tubes will impart very little signature by themselves so there is little point in buying expensive or low noise tubes.
The 6DJ8 family i.e., 6922, 7308, ECC88, E88CC, CCa, 6N23P-EV offer a range of sonic attributes and quality levels. In fact there are too many variants to list. These all have very similar operating points and can, for the most part, be interchanged. I use the Russian 6N23P-EV. The 6N23P-EV is a super tube and some even have a little rocket ship depicted on the tube to remind you of their heritage. When I bought these directly from Russia a few years ago; they were about $5 each in lots of a dozen; now they are $20 each when you can find them.
Prices for new old stock 6DJ8 family tubes are absurd and the quality varies wildly. I think that if you have to use these NOS tubes you have no choice but to buy from a known vendor who tests the tubes for transconductance and noise. Starting with a low noise tube, the second most important issue is that the two triodes be matched, if not for transconductance, at least for operating point. Both sections should match when tested for current, for instance, at the same plate voltage and grid voltage.
As for a new tube, you also have a wide selection with the Genalex Gold Lion E88CC/6922 and the Electro Harmonix 6922 as really good choices. If you are more interested in high quality new tubes as opposed to a new old stock, I would recommend Jim McShane (mcshanedesign dot net) as a very reliable vendor who will definitely not try to baffle you with thermionic voodoo bullsh*t. He's a straight shooter more interested in selling high quality new tubes than super rare, exotic, and expensive collector's items.
From Jim's we site:
For the "finicky" gear out there you can request my Genalex"Select Grade" 6922. These tubes are tested for:
Transconductance
Gain
Plate current/DC balance(twice!)
AC balance/section balance (twice!)
Noise/microphonics (twice!)
Shorts
Grid current ("gas")
In addition, these tubes receive a special run-in before testing, and are the best of the type out there.
Thanks! I have found the rectifiers in my DAC PSU make a pretty big difference in dynamics and bass. My DAC is very sensitive to vibration...sounds great without it but absolutely astonishing with good isolation...perhaps there is something about the stock tubes that made them seem weaker in macrodynamics, upper bass slam/snap...perhaps they were old. In any event, thanks for the advice on 6922s...when the current ones get old, I will be sure to investigate these.
Update post: Received Mullard 1950s 6CA4 and a Mullard 1950s 6X4 from Brent Jessee and retubed...he also included solid copper tubes with Teflon inside to cover the tubes...supposedly to help them cool better and to damp them from vibration. All I can say is they are a lot better than my 3-yr old set of 1950s 6CA4 Mullards with Sylvania NOS 6X4...which had started to lose dynamics/bass slam. But I have found overall dynamics are improved, so when trumpets blast, you get much greater definition and power...even if the trumpeter is just 'spritzing' a few notes into the air in the background, it is much more powerful...overall, jazz sounds much more balanced now. As if there is enough power to handle various levels of dynamic attacks within the music. And the signal seems more solid, less waiver. Fun!
Thanks for the update! Sounds like a great investment.
Yes, I hope so...obviously it depends on how long it lasts! But so far, it is absolutely wonderful and with all tubes now fully re-tubed...its wonderful to enjoy during the holidays.