Tubelab SE ... which 5AR4 ?

[lowtherdream]

I am planning to build the Tubelab SE. Got the board today (thanks tubelab!).
I have the 5842s (Raytheon 5842WA). Got them at RF Parts for $7.95/ea

I heard the JJ 300B sound good and I decided to use them for the project. Any other good options in that price range? I can find them at $219/pair

What about the 5AR4 rectifier ? Some NOS are very expensive ... What is the best current production 5AR4 ?
Sovtek, JJ, Penta ? other options ? equivalents (russian) ?

[Evenharmonics]

I'm using JJ for my TubelabSE. I haven't used it long enough to give you an evaluation but I've used Sovtek 5AR4 in my Dynaco amp and it started to arc after about 110 hours of use. I've heard about the quality of Sovtek 5AR4 being somewhat less than desirable for its price.

[tubelab.com]

I also use Raytheon 5842's. Bought a box of 100 for $150 about 10 years ago. Not anymore. Only have a few left.

I have used Sovtek and Shuguang 300B's. This decision was based only on cost. I have had some trouble with the Sovteks early on and New Sensor told me to get lost, so I did. I didn't use or recommend their tubes until just recently. I have been using the Shuguangs for all of my amp builds unless a customer provides his own tubes.

I have again used Sovtek and Shuguang 5AR4's without issue, although others have reported problems with Sovtek. I bought a few Sovtek 5AR4's from Triode Electronics about 2 years ago after the salesman told me that they were the best 5AR4's that he had, and that he would guarantee them. They did indeed work great in my 845 amp which pounds them hard. They are still in there. Some of the newer vintage Sovteks may be suspect.

Check the main page of my web site for some component value changes to the Tubelab SE amp when running the board on voltages commonly found in 300B amps.

[w5jag]

I have my Tubelab SE on my bench right now, so it was handy to take some measurements. With Raytheon 5842's and (probably) RCA 45's, biased to 30 mils per side, I measured the following output voltages:

Sovtek 5AR4 298 volts (0506 date code)

Shuguang 5AR4 298 volts

Mullard 5AR4 300 volts (4 serrations/plate)

Sylvania 5AR4 291 volts (marked 5V4GA, but really a 5AR4)

RCA 5V4GA 289 volts (marked GE, but really an RCA)

The line voltage was measured and constant at 122 volts, I allowed each tube a ten minute warm up, and I held the 45's to 30 mils per side, to keep the playing field level.

I make no claims to having great hearing, but with fairly low sensitivity Yamaha speakers here in my ham shack, and under these conditions, the RCA 5V4 easily sounds best to me, followed by the Mullard, and I really can't tell any difference in any of the others, at least at these low currents. I don't think the Sovtek sounds very good at all at high current draws, which is unfortunate, as it is a good looking tube and priced right.

The Sovtek, RCA, and Sylvania have a few hundred hours each on them. The Shuguang I got last weekend at HamCom and has less than an hour on it. The Mullard was a $10 hamfest special, and has who knows how many hours on it - it looks like it has seen a bunch. I didn't have any GE 5AR4's here at the house. I have never had a JJ 5AR4, so can't comment on it.

I have managed to pouf Sovtek, Valve Art (Shuguang), and GE 5AR4's. If you are an oaf like me and have a callous disregard for ratings, the 5AR4 can be a fragile tube. I have never blown any rectifier, except for a 5AR4. I don't even recall ever seeing a bad rectifier, except for 5AR4's.

Win W5JAG

[lowtherdream]

thanks for all the info tubelab.
I picked the suggested Toshiba 2SK3563 and will have to buy suggested updated values of resistors and caps.
For the transformers, I will go with Edcor. Not sure if I will go with separate xfos for the plate, rectifier and filaments, or go for the AIO.
For the output transformer, I think I will try the Edcor CXSE25-8-2.5K.

Great info w5jag. I wish I had all these 5AR4's to test with.
I will try to get my hands on a RCA 5V4GA and try the JJ.

Looks like there are a lot a good deals at hamfests. Too bad there is nothing in my area. I guess I will have to cross the border and find me a hamfest. Where is the best place to find treasures ? Dayton or smaller tickets ?