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New production 6SL7 and 6SN7

m1garand

Member
2001-11-27 8:10 pm
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.
 
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
 
TUNG SOL, so far the best!

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!
 
m1garand said:
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.
 
m1garand said:
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.
 

anatech

Administrator
Paid Member
2004-06-06 8:31 pm
Georgetown, On
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
 

anatech

Administrator
Paid Member
2004-06-06 8:31 pm
Georgetown, On
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
 
Thanks Chris.

I did mean the anode material, not the mechanical part, it seems that the cathode material bariumoxide was different in the past, I have try a lot of tubes and sometimes the new ones are better, special the high gm triodes with gyrator loading like the 6C4N-EB like I have now tryed, the old telefunkes are sweeter and that is relaxing listening, so What precise is the way to make good tubes the bariumoxide, the 6H9C from russia is to hars, I have try it in a lot of possibilities srpp, mu, to lean to hars, maybe the ebay source was no good I don,t now, the 6H8C in a srpp sound oke, 0n 10 ma idle. Do now I make only hybrides

regards
 

SY

diyAudio Moderator Emeritus
2002-10-24 10:19 pm
Chicagoland
www.SYclotron.com
From my own direct experiences comparing real NOS tubes to some new ones, well designed new tubes are superior.

Ditto (and thanks for your other thoughts on this). I haven't tried new power tubes, but the best of the small signal tubes I've tried all seem to be new manufacture. For example, I love the CV1988 and 5692s that adorn my amps and preamps, but the Electroharmonix 6SN7s I tried had better linearity and consistency.
 
6C4N-EB high transcondutance triode loaded on a mosfet gyrator its fast, and sounds very nice, a lot detail.
afcourse a lot is gone with the compression of youtube but a idea I hope is left over.

this sound is from a hybrid mosfet tube amp, 6C4 then 6N6P who is dc coupled to mosfet powerstage, it is here on
this forum so look, I will redrawn it with the new tube.

6H8C and 6H9C are hars and to lean, special the 6H9C has no balls, the telefunken ECC83 is a lot better, a whole lot.

6C4N-EB gyrator loaded plate follower - YouTube
 
Last edited:

anatech

Administrator
Paid Member
2004-06-06 8:31 pm
Georgetown, On
Hi SY,
I haven't tried new power tubes, but the best of the small signal tubes I've tried all seem to be new manufacture.
Well, 6L6EH (6L6GC) work very well in Fender Twin guitar amplifiers. For those who know, 'nough said right there! By direct physical comparison, the 6L6EH has about the same size plate structure as every NOS 7581A I have. The glass is heavier, most people report the heavy glass used in Russian manufactured tubes. Anyway, the 7581A has the same plate characteristics of 6L6GC tubes of old, except that the plate dissipation is rated at 35 watts, not 30 like the GC models. I'm going to strike down another myth while I'm on the topic.

All,
The 5881A is an improved substitute for the 6L6 and 6L6GA. The 6L6GC has a 30 watt plate (as mentioned above) while the 5881A is rated for a full 25 watts. Hmmm, someone or some many are reporting with incomplete information.

Back on topic. Original EL34 tubes are real pentode tubes and rated for a pretty high plate voltage (800 VDC I think). Their plate power rating is a lowish 25 watts. Normally found as a skinny tube. My beef is that they overheat too easily, and they suck about 1.5 amperes of heater current. Ahh, what's wrong with this picture folks? A 6L6 requires about 0.9 amperes of heater current while having a higher plate power rating. The 7581A also requires only 0.9 amperes too. The extra heater power is of course converted into heat, something the little EL34 can ill afford. Long story short, I use a 6CA7A, which is properly a beam power tube, that is very happy in freshly vacated EL34 sockets. Oddly enough, my ears are happier as well when the EL34 goes away. 6CA7 tubes last longer as well. Keep in mind they are a little bit wider, so there are amps designed without enough room between tubes to accommodate them. The thing is, those are also not spaced widely enough for EL34 tubes either. Just an unhappy design all around.

In case I forgot to mention this, there is zero wrong with good brands of newly manufactured power tubes. In fact, late 60's power tubes of good lineage fail in the Fender Twin amplifier. I'm using the Fender Twin as an example because it exceeds the maximum plate voltage ratings for the 6L6GC, which this amp was designed to use. The normal plate voltage in these amplifiers runs around 475 VDC while the tube is rated for 450 VDC. NOS tubes often hum and get hot, or simply turn cherry red while humming loudly. These are not a good sign in a tube amp.

-Chris
 

anatech

Administrator
Paid Member
2004-06-06 8:31 pm
Georgetown, On
Hi kees52,
6H8C and 6H9C are hars and to lean, special the 6H9C has no balls, the telefunken ECC83 is a lot better, a whole lot.
I respect were you are coming from. I would like to mention that any sounds tubes make are from defects. Crackles, hissing, thumps and bangs. Not to forget the lovely ring you can get from cheap tubes.

The character of sound a tube lends to a circuit is created from the interaction of the circuit design, the passive parts and of course, the tube characteristics. Tubes do not sound warm or edgy or soft. If the circuit is designed for the "boogey" tube of a certain type, then all tubes manufactured to those characteristics should sound very similar in a well designed circuit. If there is no feedback used, then everything depends on the interplay between the tube characteristics and the circuit. Take a "hard" sounding tube from one circuit and place it in another and you may have an entirely different impression of how the tube sounds. Never mind that some tubes marked as one brand may be from a different factory that makes another brand. This makes life for people who want to quantify the sound of a tube brand kinda difficult. This is all old news though.

-Chris
 
It's good to hear that there are some reliable 6SN7s being made now. My previous experience was poor. I like the look of octals, but for the sake of reliability and very low cost have used the 9-pin 6GU7, a 6FQ7 replacement that was very popular as a crt driver in 60's color TV sets. Although the plate voltage rating is lower, I pulse tested a number of them and found them reliable at high voltages as is seen with similar types marketed for deflection circuit use. The total plate rating is 6 Watts, similar to the 12BH7A and 6CG7/6FQ7. The 6CG7 shares the 6SN7 curve set up to the power limits.
Hi SY,

Well, 6L6EH (6L6GC) work very well in Fender Twin guitar amplifiers. For those who know, 'nough said right there! By direct physical comparison, the 6L6EH has about the same size plate structure as every NOS 7581A I have. The glass is heavier, most people report the heavy glass used in Russian manufactured tubes. Anyway, the 7581A has the same plate characteristics of 6L6GC tubes of old, except that the plate dissipation is rated at 35 watts, not 30 like the GC models. I'm going to strike down another myth while I'm on the topic.

All,
The 5881A is an improved substitute for the 6L6 and 6L6GA. The 6L6GC has a 30 watt plate (as mentioned above) while the 5881A is rated for a full 25 watts. Hmmm, someone or some many are reporting with incomplete information.

Back on topic. Original EL34 tubes are real pentode tubes and rated for a pretty high plate voltage (800 VDC I think). Their plate power rating is a lowish 25 watts. Normally found as a skinny tube. My beef is that they overheat too easily, and they suck about 1.5 amperes of heater current. Ahh, what's wrong with this picture folks? A 6L6 requires about 0.9 amperes of heater current while having a higher plate power rating. The 7581A also requires only 0.9 amperes too. The extra heater power is of course converted into heat, something the little EL34 can ill afford. Long story short, I use a 6CA7A, which is properly a beam power tube, that is very happy in freshly vacated EL34 sockets. Oddly enough, my ears are happier as well when the EL34 goes away. 6CA7 tubes last longer as well. Keep in mind they are a little bit wider, so there are amps designed without enough room between tubes to accommodate them. The thing is, those are also not spaced widely enough for EL34 tubes either. Just an unhappy design all around.

In case I forgot to mention this, there is zero wrong with good brands of newly manufactured power tubes. In fact, late 60's power tubes of good lineage fail in the Fender Twin amplifier. I'm using the Fender Twin as an example because it exceeds the maximum plate voltage ratings for the 6L6GC, which this amp was designed to use. The normal plate voltage in these amplifiers runs around 475 VDC while the tube is rated for 450 VDC. NOS tubes often hum and get hot, or simply turn cherry red while humming loudly. These are not a good sign in a tube amp.

-Chris

It is telling that there's only one pair of "5881A" on Ebay (they're Chinese), and none of my manuals or the sites I checked have a data sheet. The physical appearance is also much different than the 5881 which makes me believe they're likely remarked counterfeits of a "A" type that doesn't even exist. Ironically the listing shows the plates at 23 Watts. Renumbered tubes on Ebay should be reported as counterfeit. Sellers should use the real numbers and can still mention others as keywords. It may actually be good quality tubes that fail in the Fender Twins. The screen supply is 470V through 470 Ohms, fused at 100 mA per pair of 6L6GCs. That's very high, about 200V above the typical operating shown in the data sheets. A look at the curves shows that screen current skyrockets when the plate current is high and plate voltage gets low, which a guitar amp drivin into clipping sees a bunch of. The screens are only rated at 5 Watts. Ironically some inferior tubes that can't pull the plate voltage as low would end up protected from the problem. That Y2K Fender design, not from Fullerton, is clearly marginal. But in fairness, many other tube amps also fry the screens under some conditions.
 

phi70

Member
2006-10-13 5:23 am
Anyone care to find a vintage 6SN7 that looks remotely like a "Tung-Sol reissue"?

Got a pair of each of those so called reissues and compared them with my old noisy almost dead Tung Sol 6SN7GTand 6SL7GT.

The new ones are at least 3/8" taller, the shape, length of the plates, and rods don't even remotely resemble the old ones. Looks like a different tube type altogether. Heck even the stubby sovtek 6SL7GT looks more like a real vintage TungSol 6SL7GT.

They sound OK, but passing off as reissues? That's a bit disgusting.
 
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

I used this EH golden on my Cary SLM-100. For my personal taste, the sound changed as more hiss :rolleyes:... the smooth was gone and now use old RCA and I am happy.

May the gear compilation with 4 PP EH KT88 is an issue... also replaced the KT 88 with the new Golden Lion's and the sound was to muddy, no more smooth and mostly dark sounding...

In other words ... you have to spend much until you are happy (specially with the KT88's)

Cheers

Hp