Just found a couple Amperex 12AX7's - how excited should I be?

[NamaEnsou]

I was doing some cleaning up and found an ancient looking McMartin amp with one RCA 6L6 GC and two Amperex 12AX7's that have a singularly confusing bit of labeling. In white about the top they both have the forward slash ECC labeling, but while both tubes both above in white and below in orange "12AX7" one has the expected ECC83 while the other says ECC81.

Unfortunately I also found an old, and very similar looking Bogen, but there were no tubes left in its empty sockets. Kind of spooky when said that way, but at least it was light out.

I'm pretty happy with the tonality my Splawn is getting with its full complement of JJ's in all positions but am curious that if I were to try one or both of these in my amp, where would be the best place to do so and what kind of changes might one notice, if any?

Made in Holland; I don't think I've ever had anything from there before.

 

[Blue Strat]

ECC81 is a 12AT7, ECC83 is a 12AX7. Try them in V1. Rather than speculate on what changes you might hear without knowing what you're using now (which is impossible) and describing the differences in undefined adjectives, it would be more productive for you to try them and let us know.

 

[NamaEnsou]

I'll try them both tonight and see if I can hear anything but might have to wait till Sunday when I can actually turn it up.

The labeling doesn't strike anyone as odd? It's literally "12AX7/ECC81", in one screened line right above where it says Holland.

 

[J M Fahey]

Is that something to be excited about?

Just try them and decide for yourself.

 

[Timbre Wolf]

If it is truly made in Holland, then it will have an etched code on the lower side of the glass. If that code says something like I65 or I66, then it is a 12AX7. It would be easy to distinguish from the plates, if you posted a couple of clear photos.

- Thom

 

[damian1]

I find the amperex 12ax7s to be a little bright. That said I still really like them. I have orange globes and a bugle boy. Good score.

 

[NamaEnsou]

I find the amperex 12ax7s to be a little bright. That said I still really like them. I have orange globes and a bugle boy. Good score.

I tried four tubes in the #1 socket tonight and the Amperex both seemed to sound a little throatier in the mids with no change in gain or sparkle when compared with the JJ. The other tube came out of an old piece of equipment and the yellow label is impossible to read, but it seems like a 'backup only' tube from the low level check.

Sunday I'll get a chance to swap them out between songs at band practice and see if there's anything I can tell at higher volumes.

 

[Blue Strat]

One big variable is: How strong are these tubes? if they're weak they're not representative of how they should sound.

 

[Barnzy]

I have two Amperex tubes labelled as Rogers. One is a 12ax7 and one is a 7025. I really liked them in my Vic 5112. I found them to have alot of clarity which I seem to prefer in tubes. There is almost no background noise on the 7025, so much so that I thought it was a dud when I first plugged it in until I heard the first guitar sound. They are my only European tubes and I was really impressed. I found them to be well balanced with nice highs and also rich lows. I still like my RCA 7025 a bit better in my 5F1, but not by much. Nice tubes....

 

[Timbre Wolf]

I have two Amperex tubes labelled as Rogers. One is a 12ax7 and one is a 7025.

Those might have been made in the Philips factory in Ontario, Canada. Does the etched code begin with a lower-case "r"?

Here's a found image of a Canadian "7025" similar to those labeled Rogers, showing the codes:

 

[Barnzy]

Those might have been made in the Philips factory in Ontario, Canada. Does the etched code begin with a lower-case "r"?

Here's a found image of a Canadian "7025" similar to those labeled Rogers, showing the codes:

Mine both have "Holland" etched on the top edge of the tube where the flashing turns to clear. The 12AX7 has a code that looks like "41A2" , but it's pretty hard to read. The 7025 has a code "42D3". The "4" may actually be a triangle though...Can you help confirm if Amperex based on that?
Thanks Thom,
Barnzy

 

[Timbre Wolf]

Mine both have "Holland" etched on the top edge of the tube where the flashing turns to clear. The 12AX7 has a code that looks like "41A2" , but it's pretty hard to read. The 7025 has a code "42D3". The "4" may actually be a triangle though...Can you help confirm if Amperex based on that?
Thanks Thom,
Barnzy

Well, "Amperex" was a label that Philips put on tubes from several factories. Same with "Miniwatt" and with the bugle boy logo. What I can confirm is that those tubes were made in the Heerlen, NL factory (the "4" is actually a sloped triangle). Might have been 1961 & 1962, or perhaps 1971, 1972 - depends on the type code above that line. If you want to make sense of which tubes are being discussed, you must use those etched codes to identify the factory and the dates.

- Thom

 

[Barnzy]

Well, "Amperex" was a label that Philips put on tubes from several factories. Same with "Miniwatt" and with the bugle boy logo. What I can confirm is that those tubes were made in the Heerlen, NL factory (the "4" is actually a sloped triangle). Might have been 1961 & 1962, or perhaps 1971, 1972 - depends on the type code above that line. If you want to make sense of which tubes are being discussed, you must use those etched codes to identify the factory and the dates.

- Thom

Thanks Thom...what do you mean by "type code above that line?" Is there more etching on my tubes to look for?

 

[Timbre Wolf]

Thanks Thom...what do you mean by "type code above that line?" Is there more etching on my tubes to look for?

Yes - there is a code above that, signifying the tube type and revision number. I'd linked a useful reverence site above, but here it is again: http://www.tube-classics.de/TC/Tubes/Valvo/Phlipscode.htm
Your tubes probably have either I65 or I66 on that upper line. Follow links on that same Tube Classics site to see the ECC83 examples.

- Thom

 

[Barnzy]

Yes - there is a code above that, signifying the tube type and revision number. I'd linked a useful reverence site above, but here it is again: http://www.tube-classics.de/TC/Tubes/Valvo/Phlipscode.htm
Your tubes probably have either I65 or I66 on that upper line. Follow links on that same Tube Classics site to see the ECC83 examples.

- Thom

Again, thanks. If you ever write a reference book on tubes I will be one of the first to read it....

 

[Barnzy]

Just another follow up here...sorry to derail the thread. I am certain that my tubes do not have a type/revision line. Is it possible that Rogers ordered their batches without this? I know that Rogers labelled these tubes as stated...12ax7 and 7025. But the construction looks the exact same. Tubes never fail to interest me....

 

[Timbre Wolf]

That code is probably there, but very faint. Sometimes they're extremely difficult to see. Check in full sunlight.

- T

 

[Jeff West]

Even if you dont find a type code, you can verify 1961 and early 1962 for those by presence of a halo getter ring at the top, and it will be larger in diameter than in other 12AX7s, like Blackburn Mullard or RCA. Larger than the halo in Thom's Electrohome photo above. Also larger than later '60s Dutch Amperex specimens.

If you find the type code on '61 (delta)1A2 it should be "I63".

If those Rogers have solid disc getters on top instead of halos they are '71-'72 (I66). I don't recall seeing a Rogers branded I66 but that doesn't mean they aren't out there.

 

[Timbre Wolf]

Even if you dont find a type code, you can verify 1961 and early 1962 for those by presence of a halo getter ring at the top, and it will be larger in diameter than in other 12AX7s, like Blackburn Mullard or RCA. Larger than the halo in Thom's Electrohome photo above. Also larger than later '60s Dutch Amperex specimens.

If you find the type code on '61 (delta)1A2 it should be "I63".

If those Rogers have solid disc getters on top instead of halos they are '71-'72 (I66). I don't recall seeing a Rogers branded I66 but that doesn't mean they aren't out there.

Again, thanks. If you ever write a reference book on tubes I will be one of the first to read it....

Id like to read Jeff's book, first

 

[Barnzy]

Even if you dont find a type code, you can verify 1961 and early 1962 for those by presence of a halo getter ring at the top, and it will be larger in diameter than in other 12AX7s, like Blackburn Mullard or RCA. Larger than the halo in Thom's Electrohome photo above. Also larger than later '60s Dutch Amperex specimens.

If you find the type code on '61 (delta)1A2 it should be "I63".

If those Rogers have solid disc getters on top instead of halos they are '71-'72 (I66). I don't recall seeing a Rogers branded I66 but that doesn't mean they aren't out there.

Thanks Jeff and Thom. Here is my 12AX7 labelled Rogers( paint gone now) beside my one Mullard that I have. Terrible iPad picture, but you can see the huge getter on the left tube. Thanks for teaching a man to fish....

That code is probably there, but very faint. Sometimes they're extremely difficult to see. Check in full sunlight.

- T