Best or smooth sounding 6DJ8, 6922, 7308 tubes? Amperex? Telefunken?

I have a pretty harsh sounding system with my TATE decoder so I bought 2 x-10 tube modifiers to smooth down the sound.

One x-10 needs new 7308/6922 tubes and I was wondering what tube sounds the smoothest.

Telefunken, Siemens, Phillips, RCA, or others.

Is there really much difference between them?

And what is the best sounding low priced 6922-type tube?

Thanks ...

 

Wow,

I never expected 'THE MAN' to answer.

Anyway, thanks Steve.

And because of you, I just bid on a QUAD set of Amperex 6922 white label pins on ebay.

I was scared to buy anything on the bay because I heard most are fake Russian tubes but those are mostly TELEFUNKENS.

Would a match set of four sound best? I know that seems obvious but someone said that a mixed set may sound best instead of a matched set.

Appreciate the time to respond Steve.

- Terry


____________________________

 

Save your pennies and get some NOS Amperex 7308's - I have been running a pair in my Musical Fidelity tubed buffer stage for over 5 years and they are still going strong. They really make the high end come alive when playing back cd's - cymbals ring out, shimmer and then decay naturally. Check out Vacuum Tube Valley's site, find the back issue about the 6DJ8/6922/7308 family of tubes and learn about what to look for to get real Amperex USA built ones (they have etched datecodes which tell where and when they were built, and small ridges in the glass at the top of the tube) http://vacuumtube.com/vtv_issue_17.htm . I recently picked up a spare NOS set via Ebay for about $60 - they tend to usually go higher for a pair, especially if you buy them from a retail/storefront operation. Upscale Audio usually has some in stock - the owner explains the characteristics of different brands, when they were made, and recommends where they will work well. Some of the 6922 types get good reviews - read up and then start searching. http://www.upscaleaudio.com/view_category.asp?cat=42

 

Yes, The Amperex 7308 gold pins are the one to get. I used them in my dynaco PAS-4 preamp and they sound rich and smooth.

P.S. shouldn't you be known as the "quadfan" if you are using a Tate?!

 

I tried some Soviet 6922's and NOS Phillips 6922's and neither helped improve the sound all that much through the buffer stage - the Amperex 7308's do everything right, and make the sound become more lifelike through my stereo.

 

I agree! My favorite 6922 tube is a USA made Amprex gold pin, white label. I believe late 50’s made on Long Island, New York. Colored in all the right places.

Blackburn Mullards are fairly smooth too but you got to find old ones from the 40’s and 50’s, they can be awesome too.

There’s a pinched waist Amprex made in Holland (I think) that are VERY expensive (around $200 a piece) that are amazing.

 

Yes, I am a quadfan but not the quadfan.

Actually, I have 2 tates, one silver and one black and 2 qsd-1's. The qsds were completely restored but the channels seem off center while the tates are amazing as is.

I know most people here, and Steve too, think synthesized quad is bad but personally I think if someone like Steve, with his equipment, took a tate and made a sample quad mix of say 'Electric Ladyland' or "Ambrosia's 1st album" using a clean vinyl disc into a tube amp, to a tate, then to a tube preamp out to a hi-end storage disk he would be amazed.

I just can't listen to stereo any more when great surround is one button away. Plus, all of my movies and tv are also sent through the tate because the tate sounds better than the 5.1 mixes.

 

I have had some luck with Russians and Philips in the 6922.

 

This too!

Joe is usually right on.

http://www.audioasylum.com/scripts/d.pl?audio/faq/joes-tubes.html

 

Thanks for that link!

 

I use 3 Amperex 7308 PQ's (1962 White logo) in my Wavestream phono stage. I believe all 7308's made were gold pin. From what I understand, the main difference between the 6922 and 7308 is the 7308 has both triode sections matched and the tubes all meet very tight specifications, FWIW.

 

Here is what I bought:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=5801750956&rd=1&sspagename=STRK:MEWA:IT&rd=1

Amperex tubes ...

 

I couldn't agree more. There are 3 versions of the Amperex 7308 PQ (USA) Gold Pin Tubes and they are the White, Green and Orange label variety. I am currently using the White lable version and it is a stellar performer and is much better than all of the Amperex Bugle Boy or Orange label Tubes I've tried in the past.

~Maxx

 

Here is Joe's Tube Lore's test. I took out the other tubes and highlighted his favorites ...

The 6DJ8, 6922, 7308 Test

Special warning to Audible Illusions preamp users:

The one you can say for the Sovtek is that you can run it hard and it can take it. Unfortunately the classic NOS tubes in this family just cant take this kind of treatment and will rapidly fail when used in these units (and some of you guys have the fried tubes to prove it!). So you AI users are probably best off limiting yourselves to the Sovtek, the Russian 6H23N & 6N1P, the 7DJ8 and the E288CC. There may be others the range of tube types and variations is quite literally bewildering but these are the ones I’m aware of that should be able to handle the higher stresses of this brand of preamps. I review the Edicron, Siemens E288CC and 6H23N here but there are other brands for some of these. I’ve seen Phillips E288CCs & Amperex 7DJ8s advertised on some web sites in the past and there are probably others. It might be worth your while chasing them down & evaluating them for yourself to increase the number of alternatives for use in your AI.

A Note on Numbers

The 6DJ8 family was originally developed by Amperex. The first tube in the family was the steel pinned 6DJ8 followed by the gold pinned 6922 and 7308. These latter two were premium versions rated as 10,000 hour life tubes. The 6922 was a premium industrial version and the 7308 was the top of the line guaranteed low noise version. Frankly, I’ve measured & listened to a lot of these and there is no correlation between model # and sound quality. Some of the best sounding tubes in this family are 6DJ8s and some of the worst are 6922s & 7308s. So take each tube on it’s own individual merits rather than judging it by its model number or pin material (gold pins do not necessarily = better sound). The Europeans used different model numbers to identify these tubes, by the way. In their numbering system the 6DJ8 was an ECC88, the 6922 was an E88CC and the 7308 was an E188CC. Oh, by the way, a 7DJ8 is basically a 6DJ8 with a 7 volt heater voltage rather than the 6DJ8’s 6 volt rating. What does 6H23N mean? Who the hell knows! I sure don’t.

Physical Structure:

The late 1950’s and early to mid ‘60s tubes in this family had a unique internal structure. Starting at the bottom of the tube and working our way up, first we find the wiring leading up from the pins to the tube’s internal structures. Next is the lower mica spacer it’s a horizontal round disc of mica. This can be round with a serrated or scalloped edge (like a Siemens), or kind of a smooth edge disc with a slightly square shape with rounded corners (like on an Amperex or Sovtek). On top of this are the two vertically oriented plate structures. In this tube type the plates always seem to be painted grey. On top of the plates is the upper mica spacer its just like the lower mica spacer. Up to this point I’ve just described 90% of the 9 pin miniature triodes in the world it’s above this point that things differ. The next structure up is the unique one it’s a horizontal, circular, metal disc supported by two metal bars. I’ve seen & heard this referred to as a shield or a splatter shield. Which name is correct & what is the purpose of this structure? I don’t know, but most all early 6DJ8 family tubes have it. Above this is the getter halo.

The halo is usually a metal ring supported by a single metal bar. On some tubes, like very early Amperexes, the getter halo isn’t a ring but instead is a two part metal structure made from wire in the trough shape of the letter D. Tubes with this type getter halo are commonly referred to as D getters. Go figure. You will often find a different internal structure in what are apparently late production 6DJ8 family tubes from the mid/late ‘60s through the ‘70s. These tubes sometimes had a simplified internal structure that eliminated the splatter shield / getter halo arrangement. In these tubes two metal bars angle up from the upper mica spacer, almost to a point, with a small metal disc on top. Viewed from the side this metal structure on top of the upper mica spacer looks a bit like the letter A hence the nickname A frame. The other exceptions are some late Siemens 6922s & 7308s that just have a single metal rod rising above the upper mica spacer with a ring shaped getter halo on top a practice copied in the Russian 6922s and 6H23Ns.

Das Toobs:

Enough prologue, on to the tubes! This time out I’m not going to group tubes by quality, instead I’ll take them one at a time by brand & give a brief capsule on each. It had been a while since I listened to some of these guys so I pulled & reviewed my old listening notes, reassembled all the tubes and spent an evening swapping and listening to each pair in my Thor DAC. Siemens E288CC (with shield, gold pins) More transparent & dimensional with better bass than the Edicron. Also has more palpable vocals and a more lively, real sounding presentation than any of the above. But it’s not even close to Siemens best in this family. Expensive and hard to find too. But the best so far....

ONE OF THE BEST: Siemens 6922 / E88CC (with shield, gold pins) Now things are getting more interesting. It’s lively, has a palpable & real quality to individual performers with greater dimensionality than any of the above tubes. Warm, lively & transparent with an extended high end. This is a classic tube and an excellent choice in this family if your system is not already over the top in the high frequencies. Often found labeled as a made in West Germany RCA for as little as $20 a pop. An absolute bargain....

Siemens 6922 / E88CC, RCA label (A frame, gold pins) This tube is similar to the earlier 6922 above. Vocals are slightly bigger and slightly more forward, the highs are a bit softer and the overall sound of the tube is a bit warmer. Music is presented with a warm, vibrant acoustic. Very nice & musical, though it might be a bit dull in a system that’s already dark in balance. Another excellent tube...

Siemens 6DJ8 / ECC88, RCA label (with shield, steel pins) Kind of lives in between the two 6922s above. Warm & vibrant, with a slightly forward balance similar to the A frame. Slightly more extended highs than that tube, however. Another very nice tube, frequently found labeled as a made in West Germany RCA....

Siemens CCa (with shield, gold pins) This tube is a premium version of the 6922. It is also one of rarest & most sought after tubes in this family and is priced accordingly when you can find it (not often). Slightly more dimensional, transparent & focused sounding that the Siemens 6DJ8 and 6922s above. It lacks a bit in bass punch compared to those tubes however and is slightly dry sounding in comparison. In short maybe better in some ways, but not a reason for living. In other words, if you are stuck with living with the lesser Siemens tubes don’t worry about what you are missing....

ONE OF THE BEST: Siemens 7308 / E188CC, RCA label (with shield, gold pins) - Sacrilegious comment time. I prefer the slightly warmer, more vibrant and wetter sound of this tube to the sound of the CCa. Closest sound among the Siemens line to the sound of my favorite Amperexes (coming up soon!)

Siemens 7308 / E188CC, Phillips SQ label (no shield, with getter halo) Warm & transparent. Very close to the shield version above in overall sound quality. Another excellent tube...

Mullard 6922 EE88CC, Great Britain (shield, gold pins) This is a Great Britain manufactured tube, not all of Mullards are in this family with a lot of these tubes being sourced form Amperex in Holland. As I understand it, Mullard’s 6DJ8 tube tooling came from Amperex and it looks like it every Mullard in this family I’ve ever seen looks like an Amperex inside down to the smooth edge, slightly square shaped mica spacers. Perhaps as a result this tube owes a lot to the Amperex 6922 family when it comes to sound quality. This guy’s got good bass, nice mids and a wet, ambient soundstage occupied by slightly smaller and images than the Siemens and Ediswans. A nice tube overall though not quite up to the level of the best Amperexes.

Amperex 6922, JAN Orange label, US (shield, gold pins) A little sharp in the upper mids / lower treble. Good upper bass and highs. Vocals lack balance & body A bit disappointing. This tube sorta sucks...

ONE OF THE BEST: Amperex 6DJ8, Orange globe logo, Holland (shield, steel pins,) Much better than the above tube No comparison in fact. Warm, vibrant, lively, grainless, transparent Amperex sound. Killer tube. Almost as good as my reference Amperex 6922s (coming up soon). I slightly prefer this tube to the best of the Siemens 6DJ8s, 6922s & 7308s.

Amperex 6DJ8, Bugle Boy logo, Holland (shield, steel pins,) Similar to the above tube with a slightly larger soundstage & more ambience, trading off a bit of impact and bass extension. I prefer the globe logo above to this tube by a small margin in spite of this tubes vaunted reputation. But still a good tube...

Amperex 6DJ8, RCA, Holland (A frame, steel pins) - More forward vocals than the Bugle Boy. Sweeter highs too, with bigger, slightly less focused images. A little closer to the Globe logo 6DJ8 overall in character than it is to the BB....

Amperex 7308, Orange globe logo, US (shield, gold pins) More focused and palpable than the Bugle Boy & A frame 6DJ8s. A bit like the Globe Logo Holland 6DJ8 overall. I still prefer that tube to this one but this is still a pretty good tube...

Amperex 7308, JAN, green label, US (shield, gold pins) Very similar to the globe logo 7308 above. Both could use a little more bass kick & body to vocals in my rig, but could represent a useful tuning option in a system where my favorites come across a little too lively and forceful. While this tube is highly recommended by some dealers I think a few of the other Amperexes here slightly best it...

Amperex 6922, PQ, white label, US (shield, gold pins) Another very good Amperex tube. Warm yet lively, focused, grainless and transparent. A winner one of the best. Dynamic with punchy bass to boot....

Amperex 6922, PQ, white label, Holland (shield, gold pins) Slightly more forward midrange than the US version, above, pushing vocals a bit more forward in the mix. Otherwise, very similar. Another winner...

Amperex 6922, PQ, white label, Holland, D getter (shield, gold pins) Another winner. Slightly less midrange emphasis than the round getter halo Holland above, with a bit more life. Good treble extension. An excellent tube...

___________

BEST 7308 -

Amperex 7308 white label, US (shield, gold pins) My favorite 7308 by a small margin. Bass is a bit better than the Holland 6922s. Vocals lack just a touch of body compared to the best Amperex 6DJ8s & 6922s. Still a very good tube overall...

__________

Amperex 6922, USN, white label, US (shield, gold pins) Sounds very much like the US white label PQ. Another excellent tube though it may lack just a bit of that tubes warmth & body, but I’m quibbling here....

Amperex 6922, Mullard, Holland (shield, gold pins) Sounds a lot like a Holland PQ white label. In other words a very nice tube with slightly forward vocals and a lively transparent sound...

THE WINNER:

Amperex 6922, PQ, white label, US, pinched waist (shield, gold pins) Yeow! My reference tube. An absolutely gorgeous sounding tube with an unusual physical characteristic. The glass of the tube is actually slightly pinched at the about the point of the upper mica spacer. This reduces the tube’s diameter at that point resulting in a subtle hourglass shape. The reason for this was for the bottle to actually clamp the upper mica space at its rounded corners resulting in a more rigid, less microphonic, structure. The result? A tube that defines the Amperex house sound: Lively, transparent & detailed with extended highs, yet absolutely no grain, with a punchy, dynamic bass. Mids? Lucid and palpable, thank you. The best tube in the 6DJ8 family IMO. The only downside? These guys make the rare Siemens CCas look absolutely common in comparison. Cost? If you have to ask.. If I were hunting for a tube almost as good and much more accessible? I’d hunt down some US white label PQs and live contentedly until the gods smiled on me and I lucked into some of these...

Well, that’s it. And there are other Amperexes I haven’t even touched on. While this particular manufacturer made some great tubes in this family, they were offered in an almost bewildering array and while there is a house sound there are some significant sonic differences among them. Now a word on Amperex chronology to help in your searches while I don’t know it all, here is what I’ve been able to piece together so far...

White labels the earliest tubes in this family had white labels. 6DJ8s had the Bugle Boy logo, or just the Amperex name in white, while 6922s were often labeled with the PQ logo in the shape of a shield. I have also seen the 6922 along with the 7308 with just the model number and Amperex name in white. All of these labels were very fragile and rubbed off easily.

Orange globe logos Next up chronologically, these tubes have a reddish orange label printed in a fragile ink that rubs off easily. The logo included the Amperex globe (like the drawing on the yellow & green Amperex boxes) along with the model # and the Amperex name.

Red or green labels these tubes used a thick paint like ink that will not rub off and usually just used text with no logos of any kind. You will often see 1970s JAN (military) tubes printed this way the Green label 7308 US for example.

Why is this important? Well to my ears the best sounding Amperexes were the early ones (generally) meaning all else being equal I’d be chasing white label tubes. Now there are some great globe logos, but some of them just seem to have a bit less of that Amperex magic, but hey that’s me. See what works best for you and chase 'em accordingly. Oh yeah. the best Amperexes were the US & Hollands in my opinion. You will occasionally see other countries of origin for their 6DJ8 family tubes - but IMO these two were the best and that's where I'd spend my money.



Siemens vs. Amperex

So how do the Siemens and Amperex stack up comparatively? Well, to my ears, the Siemens sound just a bit more linear, with just a touch less vibrancy and life and freedom from grain that are the hallmarks of the best Amperexes. The Amperexes sound just a bit more full bodied and lively on top and are a touch more romantic in balance. The Siemens also tend to throw up slightly larger images, the Amperexes slightly smaller, better focused images (but not small - don't get me wrong on this one). Both are exceptional tubes so I wouldn’t hesitate to experiment with either. Which would I be chasing if I were hunting for some great tubes? That’s easy both!

Danger Will Robinson!

Be careful when you chase these guys. The reputation of Siemens & Amperexes precedes them and they are frequent targets for counterfeiters. How do you know if a tube in question is the genuine article? Well, fortunately there are a few basic checks you can perform to differentiate true Siemens & Amperexes from relabeled Sylvanias and Tungsrams. First, check the top of the tube in question. Siemens & Amperexes always have small ridges in the surface of the glass on top of the tube radiating outward from the nipple. These tubes will have 4 ridges, though sometimes only two of them are easily visible. The concept here is to look down on the top of the tube. The 2 or 4 ridges should divide the circular silver top of the tube in half or into quarters. No ridges? No genuine article pass on it.

Second, check the metal shield above the upper mica spacer. On Siemens & Amperexes it’s circular with two raised rectangular sections on opposite edges of the shield. On most fakes that shield is a perfectly flat disc.

Third, about 90% of Siemens tubes have a 1 or 2 digit number molded into the inside bottom of the tube glass centered between the pins. It can sometimes be very hard to see but it’s usually there. Remember, not all Siemens have it, but if your tube passes test one & two and has the number(s), it's a Siemens.

Fourth, familiarize yourself with the shape of the glass bottle on your stock Sovteks. Note that the top is smooth (no ridges) and rather rounded and the tube is short & large in diameter these traits are common to all Russian tubes in this family. Siemens & Amperexes are only about 80 to 85% of the diameter of the Russian versions and tend to have squarer shoulders on top rather than the rounded top of the Sovtek. You should be able to spot the difference between a Russian and a genuine NOS tube just by the shape & diameter of the glass pretty easily. One warning though Sovteks often (always?) have a number molded into the bottom of the tube between the pins like a Siemens, so know all the checks and don’t depend on just one to verify the tubes origins.

Fifth, if it’s a Siemens or Amperex 6922 or 7308 it will always have gold pins. So will some cheap counterfeits, so gold is no guarantee. But if they aren’t gold its not a Siemens or Amperex, so pass on it.

Brands

SUMMARY: Be careful of getting hung up on the brand name printed on the tube. In my experience most Siemens 6DJ8 family tubes you will find in the US are labeled anything but Siemens. Why? Siemens (and most other manufacturers) served as an OEM (original equipment manufacturer) supplying their tubes to many other tube manufacturers.

While Siemens made these tubes they were labeled with the name of the company they were supplied to RCA or Phillips for example. Now not all RCAs and Phillips were supplied by Siemens, so that’s where points 1 5 on how to check tubes comes into play.

Fortunately, in many cases the tubes are labeled with the county of origin & that can help you identify a tube’s manufacturer. Made in West Germany? It’s usually a Siemens.

Made in Holland? Probably an Amperex. Made in the USA? Usually a Sylvania or an Amperex. Oh yeah a useful tip: RCA never made 6DJ8 family tubes. If it’s an RCA and has a ridged top it’s either an Amperex or a Siemens. I’d watch this brand closely if you stumble on it. Many tube dealers will sell lowly RCA 6DJ8 family tubes for $15 to $20 a tube without realizing that there is European made gold inside. Check the tube’s top for ridges, the label for where it was manufactured and if everything checks out, buy it! This is one of the absolute bargain brands in this tube type. Amperexes were also frequently OEM’d to a variety of manufacturers.

Most commonly to Mullard, DuMont, Beckman, Hewlett Packard and a few others.

The risk with Amperexes is that they do vary by vintage and model and it’s hard enough to keep that straight among Amperex labeled tubes. Which vintage / version are you buying under another manufacturers brand? Who knows? It’s just pot luck.

My biases

Take my comments within the context of my system which, although CD based, is neither grainy nor euphonically rolled off on top. As a result I value good high frequency extension as it comes through in a clean, grainless and non fatiguing manner. I also like a dynamic, transparent and lucid sound with dimensional images within the soundstage. I also like to have the performers in the room with me so I like a slightly forward, but still non fatiguing balance. If your rig is bright and forward you might want to skew towards the tubes which are softer on top & a little more laid back than my favorites. But frankly, if you are using Sovteks now, this shouldn’t really be a big problem. Well, that it folks. I hope you find the overview helpful or at the very least thought provoking & hey, if I trashed your favorite tubes - don’t worry about it! It’s just one tube freaks opinion. If they work for you, that’s all that counts.

Good luck!

Joe

 

I just bought a pair of Amperex Orange Globe 7308 gold pins for my Bottlehead Seduction phono stage. Got 'em last night. They replaced a pair of Sylvania 6DJ8's that came stock with the unit.

Didn't get a chance to listen carefully, but my quick initial impression is that the Amperex aren't as "dark" as the Sylvania. The Amperex seem to have a more depth, more bounce, i.e. life, in the mid-range and also have not only more top end, but a sweeter top end.

If I remember (and anyone cares), I'll try to report back later with more detailed findings.

FWIW, I did quite a bit of research on these and there are plenty of differing opinions. It seems that there are proponents of many of the various types of Amperex 6922s and 7308s -- White label, orange label, gold label, green label, JAN, USN, PQ, Bugle Boy, US made, Dutch made, etc. (although it does seem that the opinions of the "pinched waist" 7308's are always glowing). "Joe" of Joe's Tube Lore (mentioned in above in #12) summed it up nicely..."take each tube on it's individual merits rather than judging it by its model number or pin material".

 

Those Bugle Boy logos are great, aren't they?

 

IndyMike,

are these good tubes and is that a good price?

terry

 

I've never tried those - they're from the earlier era of production which tends to indicate that they would have been constructed to tighter quality control measures. Here's a link to help decipher the datecodes for Mullard/Phillps/Valvo tubes: http://www.audiotubes.com/mullcode.htm The tubes you've won appear to have plenty of lifespan based on the test results, so I'd say you did just fine - let us know how they sound.

 

You've pretty well summed things up... They have a reputation for a long service life, and are definitely a good value if you figure in how much usage can be gotten out of them over the course of many years.

 

The Amperex 7308 PQ was manufactured here in the States because they were required to due so in order to qualify for US Government contracts.

The Military specs on these Tubes were very strict and among other things the Military required that the two triode sections of the 7308 PQ be hand matched to within 1% tollerance.

~Maxx~

 

The mystery is solved.

Like I said at the top, I have 2 x-10 tube adapters for my tate to smooth out the sound, one working and one not.

Anyway ....

I also bought two variable power supplies, from 3 to 30 amps when I got these x-10s to help with the well-known x-10 power supply issues. Well, I saw that one of the plugs had a switch that was on 3 instead of 12 where it should be, so when I set it on 12 and booted it up, it sounded fine, no bad tubes after all.

However ...

When I listened to them (using a DCC Hotel California, Miles Davis' Kind of Blue and a MSFL Aja - three favorites that I know inside and out), after reading all that tube stuff above, I was confused.

The tubes on the front sounded different than the tubes in the rears. The ones in the front sounded harsh or high while the ones in the back sounded heavier, more bass and smoother, I guess. So I switched them out. The backs in the front and the fronts in the back. Lo and behold, now the fronts sounded smoother and the backs were now higher.

So I unscrewed the backs off and looked at the insides. One of the previous owners had removed the 2 old Phillips 6922 and replaced them with 2 Amperex 6922's. The other had the Phillips inside still. So I have proof doing an unexpected blind test that Amperex's are smoother. So now I am really excited to get those old Bugle Boys and hook all 4 up to listen.

Thanks for all the help here. Great advice. Now I can teach a class on 6922's too.

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