Tubes Asylum Questions about tubes and gear that glows. FAQ

---

[ Follow Ups ] Thread: [ Display  All  Email ] [ Tubes Asylum ]

---

[ Alert Moderator ] [ Edit ] [ Delete ]

---

The 6DJ8, 6922, 7308 saga - Part 2

152.163.213.57

Posted by Joe S on March 30, 1999 at 20:08:00

Well, hello again! We’re back with the rest of the pack, but definitely not a group of runner-ups. In fact the best of the lot are yet to come along with a few other genuine contenders – so lets jump right into the fray...

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.

Mullard CV 2493, Great Britain (no shield, getter disc, gold pins) – This tube lacks a splatter shield with just a small metal wire holding a solid metal disc with dimples around its perimeter above the upper mica spacer. The sound of this tube is very different from the 6922 above, with a less pronounced bass and less vivid highs. It does have a very nice midband, however, combined with a deep & dimensional soundstage. If you find the 6922 Mullards (and Amperex 6922s to follow) too pronounced at the frequency extremes this tube could be a valid choice representing a viable tuning alternative...

Mullard 6DJ8, Great Britain (shield, steel pins) – One of my pair of these died a year ago (moment of reverent silence please....) so I couldn’t compare it directly to the others in this shoot-out. Given the vagaries of long distance auditory memory I will not comment on specifics other than to say I remember it as quite good and worth checking out if you get the chance.

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...

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...

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...

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 occaisionally 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 - dont get ne wrong on thi 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 & Amprexes always have small ridges in the surface of the glass on top of the tube radiating outwards 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

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, Hewlitt 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 nonfatiguing 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 nonfatiguing 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 tubefreaks opinion. If they work for you, that’s all that counts.

Good luck!

Joe

This post is made possible by the generous support of people like you and our sponsors:

Kimber Kable

---

[ Top of Page ] [ Contact Us ] [ Support/Wish List ] [ Copyright © 2025, Audio Asylum, all rights reserved ]

---

[ General ] [ Speakers ] [ Tubes ] [ Vinyl ] [ Digital ] [ Hi-Rez ] [ Video Asylum ] [ Cables ] [ Tweaks/DIY ] [ Music ] [ Films ]

---