6p3s-e report

Hi folks,

I'll start by saying with confidence that these tubes are a "must try" in an st-70. I bought 16 of them off ebay at just under 5 bucks each. They sounded aweful at first, but after about 70 hours or so, they have really opened up and IMHO, they are getting way too close to the GL kt66's to justify the cost of the GL's. I cannot comment on bass because my amps only do about 700hz on up. But, midrange and treble have become very detailed and "liquidy smooth" sounding as opposed to when I first installed them. I put about 50 hours on them before I left a couple of weeks ago. I had noticed them beginning to open up before I left and after 2 weeks of my wife and neighbors playing with the system for a few hours each night, I have come home to glorious music filling the house. The GL's are asleep in a closet along side another octet of these 6p3s-e's.

Where do you have those biased? I've got a set coming that will eventually be rolled into my VTA ST-70.

I can second xlr8 on his report - i've used the 6p3s-e's in my VTA ST-70 for more than half a year now, and they sound just great. Mine is biased at 45 mA.

Russian mfg. reccommends 38-80 mv bias for those tubes. Data I have is in Russian but 80 seems a little high for an ST70

I've got mine biased at .48, no issues. I'm right at the 100 hour mark as of today and I believe they can give the GL kt66's a run for their money. They seem to just get better and better each time I fire the system up.

Absolute newbie here. I'm sorry that I will not be able to contribute, only ask for, any help.

First, I want to say this is a fantastic forum. It is one of the best, on any subject, I have come across. This can only be a reflection on the character of Mr. Latino, in particular, as well as the posters in general.

I have been an audio hobbyist for 35 years, always wanted tube power but never got to it 'till now. I have been the happy owner of a used Dynakit ST-70 for 7 days now.

Now to the subject:

I am interested in trying these tubes as another option to the Sylvania "fat bottles" my amp came with, but am concerned with the voltages. As a newbie I may just be misunderstanding tube operation. My understanding is that EL-34s in the ST-70 are exposed to over 400v "plate voltage". The specifications of the 6P3S (see below) call for 250v "anode voltage" and "grid 2 voltage".

Am I looking at this incorrectly? Are there other factors involved, such as the ability to adjust "plate voltage"? Or, is the difference in voltage not really an issue.

Thanks for any help.

Name: 6P3S-E;
# Type: Output beam tetrode, long-life;
# Application: LF power amplification;
# Cathode type: oxide, indirect heating;
# Envelope: glass;
# Mass, g: 70;
# Filament voltage, V: 6.3;
# Filament current, A: 0.84-0.92;
# Anode voltage, V: 250;
# Anode current, A: 0.06-0.086;
# Anode power, W: 20.5;
# Grid1 voltage, V: minus 14;
# Grid2 voltage, V: 250;
# Steepness, mA/V: 5.2-6.8;
# Reverse grid current, uA: 0.5;
# Microphonic noise, mV: 750;
# Socket type: rsh5-1;
# Long-life no less than 5000 hrs.

Hi Bob,

Thank you for responding to my question.

I am now excited to try different tubes starting with this one.

I really appreciate you taking the time to give me the bias in volts. That was going to be my next problem; trying to determine how to set bias to achieve a certain current level.

'Frank

[quote="fswidecki"]
That was going to be my next problem; trying to determine how to set bias to achieve a certain current level.
[/quote

OHM'S LAW is your friend! If there is anything you should master if you are going to tinker with your amps, that's it.

"OHM'S LAW is your friend! If there is anything you should master if you are going to tinker with your amps, that's it."[/quote]

OK, it looks like a simple: 1.56x40/50=1.248

Thanks, I didn't see that.

Have 6P3S-E tubes on order, will update with impressions when received and run through their paces. I also plan to try the Shuguang EL-34s, which I will report on over at the "Excellent and relatively inexpensive EL34 tubes" thread (whether you want to hear it or not).

Have 100hrs on these now. My thoughts are that they are very accurate and uniform (I have 8 and tried all of them). Low noise and in general an incredible value. I used the same supplier mentioned elsewhere: BSA79 on E-Bay. It took 20 days from the time I paid to delivery.
My ST-70 is my secondary system, my main system is entirely solid-state. As such I am not necessarily looking for "accurate" in the sound. I am not entirely satisfied with the EL34s that I have, however.
I am reading interesting things about the Genelex KT77s. Anybody try them?

'Frank

fswidecki wrote: Have 100hrs on these now. My thoughts are that they are very accurate and uniform (I have 8 and tried all of them). Low noise and in general an incredible value. I used the same supplier mentioned elsewhere: BSA79 on E-Bay. It took 20 days from the time I paid to delivery.
My ST-70 is my secondary system, my main system is entirely solid-state. As such I am not necessarily looking for "accurate" in the sound. I am not entirely satisfied with the EL34s that I have, however.
I am reading interesting things about the Genelex KT77s. Anybody try them?

'Frank

Frank,
Thanks for the update. So you have found the 6P3S-E to be accurate, uniform, low noise and a good value. That sounds good. You go on to say that you are not entirely satisfied with them. Can you share a bit regarding where they are falling short for you?
...j

Well j, I can try to elaborate. I find it rather difficult to describe sound with words.
Firstly, as I said the dynaco amp is in my secondary system. I am a long-time solid state user and want a definite tube sound(what?) for this set-up.
I have a severely limited amount of experience with tube power. My ST-70 came with Sylvania "fat bottle" EL34s which I am not satisfied with due to their overdone bass.and then linear mids to treble. To the point that it sounds to me like the speakers are bi-amped with two completely mis-matched amplifiers.
What I do really like about the Sylvanias is that the sound coming out of the amp just wraps around the room completely filling the space, not just the space between the speakers, not just the front wall of the room, but the entire three-dimensional space of my room. The 6P3S-E tubes just do not do do this. I get fill between the speakers and to a reasonable extent throughout the front wall, but just not the incredible(to me) total envelopment the Sylvanias offer.
I would be very satisfied with the Russian 6P3S-E tubes if they would but give me that "immersed in the sound" experience offered by the Sylvanias. Lacking that, I have to say they are excellent-but not what I am looking for.
As to the value of the 6P3S-E tubes; I saw on E-bay a set of four Sylvania "fat-bottle" tubes, not too long ago sold as used for over $600. When I am listening to my 6P3S-E tubes I am not thinking in terms of dollars per hour!

Frank

P.S. thanks for asking, if you want further clarification please ask. PM me or whatever. It is a help to me to bounce my thoughts off someone else. Otherwise, who knows, I am susceptible to drifting off into la-la land.

Frank,
I have not owned a Dynaco ST-70 since the early eighties, but I know what you mean about the low frequency performance of that amp. I have no experience with the updated and modernized ST-70 amplifiers that are popular around this forum. I have owned the Audio Research ST-70-C3 that reused the ST-70 chassis and transformers. That amp came from Old Colony with GE 6L6 and I never found it to offer the last word in stereo effect. My current "ST-70" is the VTL ST-80 which has little in common with the ST-70 and is among the best imaging amplifiers I have heard. It is also extrordinarily neutral in the mid and high ranges, maybe a bit thin sounding in the bottom. It is a dead quiet amplifier and the sense of silence surrounding the music is captivating. Not the old school tube sound for sure. I am running "fake" Mullard (Russia) EL-34 in it and was intrigued by your 6P3S-E experience. It may be that the 6P3S-E would be moving the wrong way for me. They are a bargain though, and might be worth trying to give the Mullards a rest. I like the non-"E" version of that tube with the clear tops and getter down around the base--they would look cool in my amp, on or off I am not sure what the "E" suffix indicates, anyone know? Regarding those Sylvanias... I won't be paying $600 for any tubes that don't say "Western Electric" on them
...j

Here is one description of the differences.

http://www.tubes.ru/techinfo/HiFiAudio/6p3s.html

Then an individual description of each.

http://www.radiomuseum.org/tubes/tube_6p3s.html
http://www.radiomuseum.org/tubes/tube_6p3s-e.html

Doesn't help me much.

Well, in my excitement I purchased the 6P3S tubes from the recommended ebay seller and received it in California after 4 weeks. Unfortunately in my excitement I had purchased the 6P3S instead of the 6P3S-E.

Anyone have any experience with the non-E version? sonic differences between the two? It's currently at 4 hours on my VTA ST-70 and it doesn't sound too bad, but haven't done any serious listening yet. They seem to bias fine, currently set at .45

Ted

I couldn't be happier than how I am now with this fantastic tube! It runs now for weeks with these. I particularly love the basses, compared to the other tubes I used to, Tung-Sol RI EL34, GL KT88 RI, Sovtek KT66 (the worst tubes I tested on my ST70).
The voices are superb, the highs are smooth, playing jazz, rock or classical music is a real pleasure.
My ST-70 gives about 428V on plates and I biased the 6P3S at 33mA each, it gives about 14W of plate dissipation; 6P3S datasheet announces 20W max plate dissipation. This is the clear top tube version, not the E version, that is equivalent to a russian 5881 (Sovtek 5881WXT is a ggod example of this).
Highly recommended!! I ordered a bunch of them, for my friend's ST-70 to check how some of my guitar amps would run with them.
Best regards,
Danskman

tTube wrote:Well, in my excitement I purchased the 6P3S tubes from the recommended ebay seller and received it in California after 4 weeks. Unfortunately in my excitement I had purchased the 6P3S instead of the 6P3S-E.

Anyone have any experience with the non-E version? sonic differences between the two? It's currently at 4 hours on my VTA ST-70 and it doesn't sound too bad, but haven't done any serious listening yet. They seem to bias fine, currently set at .45

Ted

The 6P3S-E is considered by most to be a far better tube. I'd recommend you grab some - and be sure they are tested and run in. Some have grid current issues out of the box; a few have little to no getter left, apparently from tiny bits of air leakage.

Also - the ratings for the 6P3Ss-E that are printed on the Russian datasheet are VERY conservative. This tube is a drop in sub for the 6L6GC and is quite comfortable and long lived at voltages, current, and dissipation well in excess of the Russian data. I'd recommend you use the 6L6GC data in determining suitability for operation in a given amp. I've sold 1000s of them, I have a very large base off experience to draw on.

The 6P3S is not as rugged (based on the few reports I've read/received), so be careful!

It's been nearly 3 years since I posted this and I am proud to say that I am still using these tubes. I've had 2 runaway on me and out of nowhere, one of them red plated on me, but in 3 years, those are the only issues. I have purchased 2 additional lots of these tubes because after making some changes to my system over the years, I have found synergy with these as opposed to some others I've tried. They are (were) cheap, low noise, long lasting and sound really good. They sound clean and strong from the bottom to the very tipidy top of the audible range. I cannot say that about the EH EL34, GL KT66, or Sovtek EL34s I've tried. For some reason, most of the others seem to be much softer, almost rolled off to a degree on top when compared to the 6p3s-e. I have designed and built my own dipole line array speakers with 1 60" magnepan ribbon and 12 Vifa 5" truncated drivers per side. The line of conventional drivers handles 45-6k HZ and the tweeter goes to infinity. They are estimated @ 101db sensitivity and can handle a massive amount of power, but 2 VTA boarded and built vintage ST-70's seem to be more than enough. I use active crossovers and a 31 band stereo eq and yes, I did sit down here with an Omni mic and a spectrum analyzer and do it right.  6p3s-e wins in this system. It is very transparent and readily shows differences in ALL recordings that are played through it. I hear supplies might be drying up, which is unfortunate. Thankfully, I think I acquired enough early on to last me the rest of my life, so I'll let you guys fight over/pay for the leftovers lol!!

You mentioned the fat bottle EL34. EH 6CA7 fat bottle sounds just like you described and AES has a matched set for $72.72. I like the flat response and clean sound compared to the very midrangee EL-34. The fat tube definitely has more Bass and highs.

I said match set but I meant Matched quad.

This is an new question posted in an older string.....I see Bob's suggestion of biasing the Russian 6p3s-e tubes at 40 to 50 milliamps per tube. Would this mean that one could bias these tubes at
.400 -.500 VDC?
...Pete

I've seen a couple reviews on these that recommend 50mA - best waveform when tested with a scope. That's certainly pushing the spec, and I'm sure that would impact the life of the tubes, but what's more important? Cost or quality?

They still look to be running around $10 each ... a real steal compared to the usual choices. Anybody try these in an ST-120?

deluxmon wrote:This is an new question posted in an older string.....I see Bob's suggestion of biasing the Russian 6p3s-e tubes at 40 to 50 milliamps per tube. Would this mean that one could bias these tubes at
.400 -.500 VDC?
...Pete

'Frank