[Oskari]

The codes on the tube don't tell me much, I'm afraid. Sylvania date codes are poorly understood.
 
Perhaps E4 = May 19?4, perhaps not.
 
SC A = U.S. Army Signal Corps.
 
966 = ?

 

[siles1991]

Wow i've been gone for awhile and tube rolling has gone to a new dimension O_O I don't think I have the guts to pull off all those mods as I have very little electronic knowledge and would break down in tears if anything happened to my LD D: Still using the RCA 6DT6A's and these are still my favorite among all the tubes i've used. Though I don't want to believe this is the limit xD any new recommendations that don't require the hardmods you guys are doing like the ol fashion strapping!

 

[Audiofanboy]

  Wow i've been gone for awhile and tube rolling has gone to a new dimension O_O I don't think I have the guts to pull off all those mods as I have very little electronic knowledge and would break down in tears if anything happened to my LD D: Still using the RCA 6DT6A's and these are still my favorite among all the tubes i've used. Though I don't want to believe this is the limit xD any new recommendations that don't require the hardmods you guys are doing like the ol fashion strapping!

 
Yeah, we don't muck around on this thread lol!
 
Still, I can personally vouch for how colossal the improvement is with these premium double triodes; it really is worth the extra effort.
 
Again, all you need is:
- Two 7-pin socket savers/testers
- One 9-pin socket or a 9-pin "breadboard"
- 20~50cm / 8~20" copper wire
- And either some basic soldering skills or some way of safely strapping those wires.
 
Honestly, if you plan your basic DIY adapter well, it is pretty easy to make. Some adapters (gibosi's for example, I believe) may not even need any soldering at all; so you wouldn't even need to "make", you could just "build". Easy, I tell you.
 
All the cool kids are running double triodes lol, it would be a shame to be left out! (I'm just kidding, but what I wrote above is still true)

 

[Artsi]

Got my octals today would anybody know the date of these tubes.Thanks.




Most of those white printed sylvania 6SL7GT tubes with construction and text like this are made in 1943-45. Tried to bid one but did not win... So if i guess it is made in 1944.

 

[gibosi]

  ......I need to roll the Tung Sol 6SU7 and Sylvania 5751 again to see how they stack up......

 
I took some time this evening to compare the 1961 US-Amperex 6922, the late 1950s Sylvania 5751 TMBP (Triple Mica Black Plates) and the 1950 Tung-Sol JAN-CTL-6SU7GTY....
 
The Sylvania has a tonality very similar to the 6922 with a superb mid range and treble. However, while the sound stage with the Amperex is exquisitely sharp and focused, it is noticeably softer with the Sylvania. And similarly, with the Amperex, micro details seem to be sharply etched against a very black background, whereas they were noticeably softer and less focused with the Sylvania. In my opinion, the Sylvania compares quite well with the Amperex OG. That said, one Sylvania typically sells for around $60 while a pair of OGs can often be found around $30. Given that, I suggest that you pass on the Sylvania and enjoy your OG.
 
The Tung-Sol is a bit more complicated.... It is quite warm, with very good clarity and transparency, and a nice 3-D soundstage. However, the upper mid range and treble response is rather laid back. Thus, micro details, which tend to be in this frequency range, are also somewhat faint. My feeling is that this tube is just not a good match for my HE-300s, which are rather dark. However, I would love to listen to this tube through a pair of HD-800s. My gut tells me this just might be a very good pairing. And further, it occurs to me that perhaps a different 6SL7/6SU7 would sound better in my current system.
 
So.....  even though I wrote very recently that I did not intend to purchase any more octals, I have decided to get one more. lol
 
In 2006, a guy with the handle Sir.Richard wrote that in his opinion, the Sylvania 6SL7WGT Gold (JAN-CHS-6SL7WGT) was the best of the breed. Of particular interest to me is this comment:
 
".......puts you front and centre - like the main instruments are just a couple of feet ahead of you -
forward of the speakers. Excellent depth and detail and solo instruments and classical music just
come alive. A real eye opener when you listen to these." 
 
http://www.head-fi.org/t/100774/top-5-6sn7-s#post_2011240
 
It seems quite likely that this Sylvania has a very different sound signature, perhaps a better match for my headphones, and so earlier today, I purchased one.

 

[mordy]

Hi All,
 
Completely agree with AFB - there is so much more listening pleasure to be had with the double triodes such as the 6DJ8 and 12AX7 families.
 
As somebody who does not have much experience in electronics I took the plunge and made different adapters. After trial and error Gibosi's no solder adapter is probably the best and easiest solution.
 
I got an adapter that allows an octal tube to be plugged into a 9 pin socket wired for 12AX7. Hopefully I'll have an octal tube soon to play with with.
 
What's next? Sub miniature tubes?

 

[TrollDragon]

Picked these up tonight from a local seller on kijiji for a great price.
 
Sylvania JAN 5751 8039 & 792?, Unfortunately they are not TMBP's but they sound good so far, he had some black plate RCA's in his mono blocks...

 
 
 
He also gave me a pair of these as one is a little noisy... I forgot what he said they were I'll have to ask him again, they are some kind of 12A?7.
Shorter plates than the 5751's,  no number on the tube and the "GE Electronic TUBE" is painted on in a raised green enamel.
He felt they were fakes of some sort...

 

 

[MIKELAP]

 

  Got my octals today would anybody know the date of these tubes.Thanks.
 

Most of those white printed sylvania 6SL7GT tubes with construction and text like this are made in 1943-45. Tried to bid one but did not win... So if i guess it is made in 1944.

 

Thanks Artsi, might i ask what is the price it sold for i paid $19.00 including shipping !

 

[Artsi]

  Thanks Artsi, might i ask what is the price it sold for i paid $19.00 including shipping !

It was auction of 3 sylvanias. One NOS, one little used and one more used. It was about 50dollars with shipping.

 

[Audiofanboy]

   
I took some time this evening to compare the 1961 US-Amperex 6922, the late 1950s Sylvania 5751 TMBP (Triple Mica Black Plates) and the 1950 Tung-Sol JAN-CTL-6SU7GTY....
 
The Sylvania has a tonality very similar to the 6922 with a superb mid range and treble. However, while the sound stage with the Amperex is exquisitely sharp and focused, it is noticeably softer with the Sylvania. And similarly, with the Amperex, micro details seem to be sharply etched against a very black background, whereas they were noticeably softer and less focused with the Sylvania. In my opinion, the Sylvania compares quite well with the Amperex OG. That said, one Sylvania typically sells for around $60 while a pair of OGs can often be found around $30. Given that, I suggest that you pass on the Sylvania and enjoy your OG.
 
The Tung-Sol is a bit more complicated.... It is quite warm, with very good clarity and transparency, and a nice 3-D soundstage. However, the upper mid range and treble response is rather laid back. Thus, micro details, which tend to be in this frequency range, are also somewhat faint. My feeling is that this tube is just not a good match for my HE-300s, which are rather dark. However, I would love to listen to this tube through a pair of HD-800s. My gut tells me this just might be a very good pairing. And further, it occurs to me that perhaps a different 6SL7/6SU7 would sound better in my current system.
 
So.....  even though I wrote very recently that I did not intend to purchase any more octals, I have decided to get one more. lol
 
In 2006, a guy with the handle Sir.Richard wrote that in his opinion, the Sylvania 6SL7WGT Gold (JAN-CHS-6SL7WGT) was the best of the breed. Of particular interest to me is this comment:
 
".......puts you front and centre - like the main instruments are just a couple of feet ahead of you -
forward of the speakers. Excellent depth and detail and solo instruments and classical music just
come alive. A real eye opener when you listen to these." 
 
http://www.head-fi.org/t/100774/top-5-6sn7-s#post_2011240
 
It seems quite likely that this Sylvania has a very different sound signature, perhaps a better match for my headphones, and so earlier today, I purchased one.

 
I'm not particularly surprised that a "Top 10" 6DJ8 tube would turn out to sound better than a good 12Ax7 variant. The 6DJ8 (and even moreso the 6922) was developed fairly late in the tube era and made for pretty critical/precise applications (the fact that Tektronix used this tube as their "staple signal triode" of sorts kind of confirms it for me, as we all know Tek did not fool around when picking tubes).
 
The 6Sx7 tubes, on the other hand, I can't make any assumptions about. Some are propbably crap, some are still considered to be some of the best signal tubes ever made. Still, while the best 6SL7 are the older WW2 era ones, the premium 6DJ8 tubes should have at least somewhat benefited of the extra 20 years of research (I just can't believe that all those engineers and scientists weren't doing anything for all that time; I mean the whole "frame grid" must have made some change in sound quality when implemented well...). So, I would expect a "top tier" 6922 to at least hold its own ground against even a "god tier" 6SL7; hell, maybe even sound as good or better (just as linear and cleaner perhaps).
 
Looking desperately all over the web for detached and pragmatic answers to "which double triode is best suited for gain preamps" and "which double triode family are the best double triodes tubes found in" and other questions, I find myself overwhelmed by how little people seem to have compared those tube types (or reported on their findings). I guess people normally just stick to what their amp uses... Just goes to show how unique we are lol!
 
Interestingly, one result that popped up a few times, when I was looking for direct comparisons of "top tier" 6922, 6Sx7 & 12Ax7 double triodes, is the suitability of the 6N30 family for this exact application, and how good these tubes were made to be, both on paper and in real world use. I'd read stuff before about how "perfect" the NOS 6N30 tubes were supposed to be in theory, but reading it again in a different context at least comforts me in my choice of power tubes lol.
 
While the 6N30 could make a excellent driver tube, it probably wouldn't be suited for our amps though (if even leaving the heater power aside), as they output a lot of current, and unless used in appropriate preamps, would not be well suited for a gain stage (low mu, extreme gm). On the opposite, The 6DJ8/6922 are very well suited for a gain stage for a similar reason though, as they have medium gain and output a lot of current too (a third of a 6N30 though lol).
 
Anyway, still looking for as many impressions as possible comparing the best 6SL7 and 6DJ8 tubes. This time around though, I'm really thinking I hit a new sound quality plateau with the '62 US 6922 that might be hard to beat. This Amperex tube is simply... gorgeous to listen to... I've never heard bass guitar or drums that captivate me that much. It's not missing anything... Simply astounding.

 

[MIKELAP]

How would the new 6922 by Genelec or other manufacturers compare to the old ones any idea.

 

[hypnos1]

  How would the new 6922 by Genelec or other manufacturers compare to the old ones any idea.

 
Hi Mikelap.
 
Don't know if this is of any help, but I would suspect the much later ones - compared to what AFB and Gibosi have been lucky enough to find - are not in the same league. This from what I personally have gleaned from various sites, and my (limited) experience with the Philips ECG 6922 JAN ('80s), and a pair of Zaerix tubes that are EXACTLY identical...they don't come anywhere near even the dirt-cheap (but excellent) Voskhod 6N23P (see Gibosi's comments on same) or my 6N2P-ERs. But of course there are OTHER 6922s!!

 

[TrollDragon]

  How would the new 6922 by Genelec or other manufacturers compare to the old ones any idea.

There has to be possibly something  good about the new tubes...
 
The guy I picked up the 5751's last night from has a nice little collection of tube gear.
 
A sweet little 18W monoblock pair that I forget the name of with a quad of new Svetlana 6L6CG's. A Prima Luna Prologue Classic with new EL34's and 2 phono stages, a Grant Fidelity p-307 and a Jolida JD9 MK II... This gear run's vintage Magnepan type speakers and most of the units have new not NOS tubes in them. 
 
So there has to be something to be said about new stock instead of chasing vintage tubes around, or it is possible that he just does not have the time or the bother to search for and acquire NOS tubes... 

 

[hypnos1]

   
Well, of course, I think this really comes down to personal preferences... While I do not have a Telefunken from the 6DJ8 family, I do have a Siemens PCC88, a Valvo (Hamburg) E88CC and the Tesla E88CC with gold pins and gold grids, and they all have a mid range characteristic of German production, which is less warm and lush than is typical of Dutch and British production. Given my ears and gear, I find that I much prefer the Amperex tonality, which is not as warm as the Mullard, but more forward and lush than my Siemens, Valvo and Tesla.
 
As the Tesla was NOS, I burned it in for 20 hours and then compared it directly to the Valvo. Mid range and treble for these two tubes is very similar, again typical of German production, but the Valvo had more bass presence, while the Tesla sounded "thinner".  As I liked the Valvo better, I then rolled in the OG. And again, personal preference, but vocals came alive. The OG has a lushness and richness, coupled with great flow and liquidity, that I find very seductive.
 
But as much as like the OG, I think my 1978 Voskhod 6N23P is just a bit better. And given that you can get these Voskhods for $3 to $5 each, they are a steal. You want to look for production years 1974 through 1979.
 
 http://www.head-fi.org/t/549508/schiit-lyr-the-tube-rolling-thread/8595#post_9625620

 
Have finally popped in the 6N23Ps ('73 &'74 with grey shields, so am hoping they might match the '75s) and WOW, you weren't kidding Gibosi. For the money, there is no equal to be sure - in fact outperform most tubes many times more expensive. And this is with just a couple of hours on them! Can't wait to get some more time on 'em and do a proper comparison with the 6N2P-ERs - first impressions are that the bass seems more extended; more to the mids, with not quite the same breadth of soundstage - but that may well open further with time...All in all I can see why you have them (almost!) at the top of your list. (Have some '70s 6N2P-ERs on the way which I am looking forward to seeing if they can put up an even better battle...).
 
As I mentioned in my post to mikelap, these Voskhods are WAY ahead of the likes of Philips ECG 6922s and even the Mullard E88CCs with gold pins - good though the Mullards are, for my taste there just isn't the same spacious 'airiness' or pinpoint separation : too 'warm' I suppose, which seems to close in the sound. But for those who prefer 'warmth' they certainly are a good tube...
 
The Telefunken ECC88s...now here's a dilemma. Germanic 'flavour' - yes, but with a bit more body than the Teslas. I really want to love these tubes, but have a feeling they aren't delivering of their best - one is pristine the other not quite so, with less clear glass; slightly 'smoky' inside and pins that show much more usage...obviously NOT a good match. Ah well, my turn to get unlucky...
Still, all is not lost - have another pair on the way, so should be able to get at least 2 well-matched set of triodes, given my adapter set-up (will be making 2 more so that 3 decent (hopefully) tubes will give me 12 possible combinations). I have a feeling I could be in for a very pleasant surprise in the near future, given the number of positive murmurings from around the 'net re the plain 'vanilla' ECC88s compared to the uber expensive TFK tubes...can but just hope...
 
At the moment, though, I am really enjoying these 6N23Ps caressing my ears...

 

[mkrzych]

Amazing guide!