New production 6SL7 and 6SN7

[m1garand]

Does anyone know if any of the current manufacturers of 6SL7 and 6SN7 are working on improving their product? I haven't heard very good things about the Sovtek and the Chinese versions. They are commonly used tubes with good performance. Does any one know how to put pressure on a manufacturer? EH owns Sovtek, and they have redesigned many of the generic Sovtek tubes with great success. Perhaps they would be interested.

James J.

[GRollins]

I have repeatedly heard of reliability problems with Chinese tubes, but have not heard anything about Sovtek. I use Sovtek 6SN7, 6922, and 6550 (plastic base) tubes in my gear here and haven't had any problems that I couldn't attribute to my stupidity; ran the bias too high on a couple of 6550s and toasted them, but I don't blame the tubes for that. Small signal tubes have given me no trouble whatsoever.

Grey

[CunninghamRadio]

Dear Friends,
We have purchased about three hundred 6SN7 and at least one hundred fifty 6SL7 tubes of new manufacture within the last two years.
The Chinese are 50/50 who knows if they will be good, or even last a month. However, the latest version of the 6SN7-6SL7 type genre from the new TUNG-SOL division of EH or Sovtec are actually quite good. They measure as well as many of the NOS we have on hand and they DO NOT suffer from the dreaded "infant mortality" that the Chinese units do.
So there you have it. Go buy the new TUNG-SOL and relax.
CunninghamRadio
By the way! Look at the new Tung-Sol 6L6G and you will find that it measures almost exactly like an original WESTERN ELECTRIC 350-B !!! If it wasn't for the top getter it would be a perfect dead ringer... We ran these babies at 400 volts screen and 700 volts plate and they just stood up and screamed their hearts out!

[Jim McShane]

Originally posted by m1garand
Does anyone know if any of the current manufacturers of 6SL7 and 6SN7 are working on improving their product? I haven't heard very good things about the Sovtek and the Chinese versions. They are commonly used tubes with good performance. Does any one know how to put pressure on a manufacturer? EH owns Sovtek, and they have redesigned many of the generic Sovtek tubes with great success. Perhaps they would be interested.

James J.

Just so you can keep it straight, EH does not own Sovtek. EH, Sovtek, Tung-Sol, Genalex, and Mullard are all tube lines owned by New Sensor Corp of New York City. New Sensor also owns the plant in Russia (Saratov) where the vast majority of those tubes are produced.

I have had a lot of very positive feedback on the EH 6SN7 BTW.

[cerrem]

I am curious as well....
I have seen Ebay auction for EH 6SN7 tubes that had gold plated pins... The tube "looked" good....
I was wondering how this tube rates.....

Chris

[Miles Prower]

Originally posted by m1garand
Does anyone know if any of the current manufacturers of 6SL7 and 6SN7 are working on improving their product? I haven't heard very good things about the Sovtek and the Chinese versions.

I have Sovtek 6SL7s and 6SN7s running in a project I did. Both these Sovteks show no signs of microphony, as there wasn't the slightest disturbance while o'scoping and sharply rapping on the Sovteks. The NOS Westinghouse JAN 6J5, however, showed a slight disturbance when given a sharp whack. Now, I have heard from multiple sources that NOS US-made 6SN7s, in particular, are very microphonic.

As for quality, the Sovtek 6SN7s include grid radiators not seen on NOS US brands. As for the 6SL7s, when used in a design derived from RCA 6SL7 characteristic curves, the Sovteks performed just as designed. These guys are real 6SL7s indeed. Sometimes, new production VTs are way off from the original specs.

The project that includes them sounds just great. They probably perform better than a lot of NOS audiophool types that go for far more $$$$$. I wouldn't worry about using Sovtek 6S*7s at all.

[Colt45]

Originally posted by Miles Prower

As for quality, the Sovtek 6SN7s include grid radiators not seen on NOS US brands.

I have some old 6N8S (=6sn7) from novosibirsk, 70's... they also have grid fin. I guess russians have always made them this way.

[anatech]

Hi Miles, Grey & Jim,
I've used products from New Sensor for years now with very few problems. The Electroharmonix brand has been nothing short of great. Their 12AX7's are very quiet as well and I'm very happy with the 6S*7's.

One of the only new tubes I can trust to install in a Fender Twin are the 6L6EH. No mean feat here. I've re tubed some of my equipment stage by stage and ended up with the Electroharmonix brand installed.

I think you're pretty safe using that stuff.

Hi Chris,

I have seen Ebay auction for EH 6SN7 tubes that had gold plated pins...

Those are available as regular product from New Sensor. Buy 'em fresh, tubes don't like to be banged around. I can't say if the gold pin version is any better. The insides are the same.

-Chris

[kees52]

the material for tubes are in the 1930 different then for the new production, we have to go back to the 1030 anode (diode)material.

I don,t now what she use then, but sound is far better with the oldest ones, try a 1920 triode if she are there that time.

[anatech]

Hi kees52,
You are talking about tubes at a time when the 6S*7 types had not been designed yet. I have many from that era as well.

From my own direct experiences comparing real NOS tubes to some new ones, well designed new tubes are superior. Before anyone gets upset, consider what the New Sensor folks have done. They used actual NOS examples and reverse engineered those tubes completely. Aside from things like heater composition (can be measured), all the characteristics any tube has are defined by electrode spacing and how solidly the elements remain in their position. There is no shortage of iffy brands out there, but the stuff New Sensor sells are very well made. Another important characteristic a line of tubes need is consistency. Anything made has variations in process. If you can control these variations to within a small error band (how close is each tube to the "bogey" tube), you will have tubes that are very close to each other as far as they behave in circuit. A tube may "sound great", but if only 2% of production work well in your particular design - what good are they?? This also gives rise to problems when some people "design by ear". If they use a highly variable line of tubes, you are now in a situation where the tubes must be hand selected parts. Read - expensive and hard to keep sounding good. All the negatives of tube based product. So unnecessary!

This brings up another point of contention for some people. Machine made things will be more alike to each other as long as the machines are properly maintained and there is reasonable quality control in place. Hand made things will vary more compared to other things made by the same people. People are not good machines, and the odd expert who is extremely highly skilled can still be equalled by a competent machine and operator combination. People are very poor at measuring tension and winding pitch by hand. For a machine, that's too easy.

Last point I'd like to make on New Sensor. The Sovtek line is an excellent line of tubes, but they are not made to western specifications. These are Russian tubes that are marked to the closest western part number. They are different tubes completely. Now, the Electroharmonix are made to the specifications of the number they are marked with. They were reverse engineered from examples thought to be the best representatives for the tube type (often RCA I'm told). I am lead to believe that the branded tubes are reverse engineered from examples of those brands they are marked as. I have no proof as I have not examined these, but the sales rep did indicate this. I'll believe him, but this would be very difficult to prove for sure by comparison. Why? Because tubes were often commodities back in the day. Manufacturers have been known to buy from each other to fill demand. There is an entire hobby built up from deciphering the markings on elements within the tube. Even the shape of the internal part can say something. Since tubes are assembled from completed grids, plates and other parts, one wonders if these were not also traded. I don't know, but that could really confuse things out there. Do remember one thing though. As time wore on, manufacturers improved both materials and manufacturing techniques. They had to increase their yield of accepted goods. So, from a purely fiscal standpoint, the product had to be improved over time. Never mind the reputation of the brand. Bad rep = rotten sales and an ex-company.

Food for thought.

-Chris