Amperex or Telefunken?

[Cliff Schecht]

So I've accrued a pretty decent collection on Amperex (Bugle Boy) and Telefunken 12AX7's but haven't found that I like one type over the other, or better stated I haven't A/B'ed them enough. For guitar amp purposes, does anybody have any insight on the tonal (and other) differences between the Dutch and German tubes? Is one truly "better" than the other?

[Phil_S]

Cliff, no Mullards?
I tend to see that the Tele's are in high esteem with the audio crowd, not so much the guitar amp crowd.

[David Root]

They both have their places in guitar amps, but Amperex has more places than Telefunken, IMHO!

In the interests of full disclosure I should say that the following refers mainly to my D-type amps, specifically #124, #13/#40 50W hybrid and a Bluesmaster.

I have been playing with Funkins in V1 and PI but '60s Amperex short plate 7025s are great in the 124 in V1 and V2, although I have a '53 blackplate RCA in V2 right now. PI is a '64 Funkin long smooth plate.

The Bluesmaster has '60s GEs in V2 and PI, but Amperex sound good too, just a matter of taste. V1 in the Bluesmaster is a blackplate RCA.

The '70s ODS has a "silver anode" (nickel) '61 Mazda in V1, a '70 Amperex in V2 and a French made '64 (Radio Technique) Amperex Bugleboy labeled 12AT7 in the PI. The Mazda gives it an old school kick I think.

I have ordered a Tungsram from Gregg Levy at Hi Test. He says they sound great, good harmonics especially in V2, and are not microphonic but don't last like the Dutch and German tubes, which is why they are $45 not $120.

[Cliff Schecht]

I may have a Mullard or two in sheeps clothing but most of what I have are pulls from old dead HP and similar equipment. They seem to prefer Amperex, RCA, GE and Telefunken over Mullard, Tung-sol and other nice brands (although this isn't a set thing, just IME).

My only Amperex 7025 is in V1 of my Express (was NOS, now it isn't ). I worry that this tube will wear out eventually but it's been going strong for a year and a half. Amazing sounding tube and very low microphonics to boot. I may try subbing this out for a triple-getter 5751 soon, I have a few pulls that I'd prefer to wear out first. I have used both Bugle Boys and Tele's in this Express and found a great combo with that 7025 in V1, Bugle Boy in V2 and a Telefunken PI (I think ribbed grey plate). Swapping V2 and V3 changes the tonality of the amp for the worse funny enough..

This brings up a good question though. What is the expected lifetime of these uber-quality tubes in "demanding" guitar amp applications?

I'm also no expert when it comes to the different plate materials and structures, although I'm familiar with the basic variants. What's the difference in sound between black plates/grey plates and short vs. long? Ribbed vs. non ribbed? Is one type more desirable than the other? Lastly, what is the materials difference between grey and black plates?

[212Mavguy]

Hi Cliff,

There is a pretty good discussion of vintage old stock 12ax7 types done up by Timbre Wolf in the Mesa Boogie owner's forum. You will have to go back several pages in the tubes section or search his posts and go through them, back a couple years at least to find his table. www.forum.grailtone.com He's also done up a table on 12at7's. Another VERY good read is the "12ax7 Shootout" in a back issue of Vacuum Tube Valley magazine. It's worth the cost of the magazine back issue for that article alone. It served me well as my primer for being able to successfully purchase vintage 12ax7's off eBay, of which I have many now, of most brands and types ever made.

The Telefunkens we know, unless they are rebranded from other makers, tend to two types: ones with smooth plates, and ones with ribbed plates. Between the two types, the ribbed plate tube has more top end to their tone. The smooth plate tubes, unless low in hours tend toward a more rolled off top end. Both types feature very strong bass and lower mid response. The pick attack in the smooth plate is not as crisp sounding as 12ax7's from other makers. The clean tones from both types are not super detailed, a bit bland, but they are smooth and pleasant. However, both types deliver excellent, smooth overdriven tones and offer a smoother sounding, very violin-y sounding, very compressed sustain when pushed heavily in the dirt, with the ribbed plate slightly brighter overall. It is this compression, smoothness, violin-y tones, and accompanying looooooong sustain which makes them work well in my Ceriatone 50w HRM. I use a smooth plate in v1, a balanced smooth plate in the PI, and a ribbed plate in my C-lator. The classic Dumble-y tones tending to be heard in the Youtube clips are well done up by those tubes.

You will find that the Tungsram 12ax7's deliver a wonderful clean tone, with a gorgeous, delicate, detailed top end. When pushed into the dirty zone, the Tungsies don't sustain as long for a given amount of gain as some other types in my experiences with them. That may not be a problem with players that don't use lots of sustained, long notes in their playing.

The most popular Amperex 12ax7 tube used by guitar players is their short plate type. I am pretty sure that is what you have in your express. They tend to have a brighter top end than their short plate Mullard cousins.

There is a whole family of similarly constructed short plate 12ax7/ecc83/7025 tube types within the "Philips family" of tube makers that Philips, the parent company owned. They include, but are not limited to: Philips, Philips and Dario Miniwatt, Amperex, Valvo, Rogers, Electrohome, Mullard, and my rather spendy $$ favorite, Siemens. Another shortplate design that features the brightest top end of all is the Matsushita 12ax7 with the 45 degree angled getter flash. They were built on Mullard tooling in Japan, the famous "Japanese Mullards." They have very low microphonics, and searing harmonics that will tear your face off in a 'wreck styled amp. The matsu-not-so-shitty is one of the most affordable Philips family shortplates out there, and long lived in my experience.

IMHO regarding wearing out preamp tubes, the PI is the hardest working and fastest wearing preamp position in a push pull guitar amp. I wouldn't worry so much about wearing out that Amperex 7025 you love as going ahead and finding more like it.

Another interesting thing that I've found is that different amps like different 12ax7's to sound their best, one tube is not the best in all applications, the opposite is true.

[billyz]

I have a Telefunken Smooth plate in the V1 of an Express build and it was the best sounding tube I have tried so far. It has everything, full , rich, detailed and Smooth, very alive too. I read some people think the Teles are thin and bright, but that is not my experience at all. I have several variations of the Diamond plate and they always are my favorite sounding tube. That being said I love a good Amperex Bugleboy as well. It is the 3D tube of tubes. The Telefunkens are said to be good for at least 10,000 hrs, so far I believe it. Just make sure your Telefunkens have the Diamond in the base, I have seen them without and they could be anything, even japanese made.

[Alexo]

Funny how one person can hear one thing and somebody else hears another.

I thoroughly enjoyed the above post about Tele's, Matsu's, etc., but I find the Tele's to have that delicate, detailed and AIRY top end, while Matsushitas sound warm and balanced and smooth, go figure!

The Bugle Boys can be amazing - definite "mojo" tone - I hate to use that word as much as anybody, but plug one of these in, and there you go. Very harmonically rich and sweet, with no trace of harshness, they make your notes glow.

A few years back, I did a big taste test, rolling a plethora of 12AX7's through an old 50's era mic pre, playing the same track (Bach double piano concerto, iirc) through the same speaker with a condensor mic in front of it. I then set up a rig to do a blind test. You don't get nearly the same feel for a tube through playback as you do via playing, but the test still had some merit, I think

Tele smooth & ribbed plates, Mullards, Toshiba, RCA black & grey plates, Syl's GE's, EI, and Sovteks were involved. Don't think I had any Bugle Boys at the time.

The only 12AX7 in this test that sounded distinctly different from any of the others was the smooth plate Telefunken. This guy had much more 'air:' you could hear the 'spaces between the notes,' and the music was more three-dimensional.

The other tubes sounded a little different from each other, but all in all, very similar. But as mentioned above, different tubes sound different in different amps, so I wouldn't read too much into this. ... But the Tele smooth plates still have that magic to me. Tend towards microphonics though, with those big ol' plates.