Dumont tubes

[AcornHouse]

I recently retubed my 1960 Guild 99J amp. It had a mishmash of tubes of unknown strength when I got it. I had some trouble with the 12AX7s and took it took my tech to test the tubes. (Luckily, the RCA long plate tested good!)

The 6L6s that I took out (and forget to bring with me to the tech, unfortunately) are branded Dumont. From what I've been able to find, they didn't make any tubes, but rebranded them.
The codes on the glass are (in orange):
ERP
80-22
———
171a

Anyone have any info on them? Who is the maker? They're probably still good as a backup.

[slider313]

Most Dumont tubes I've come across were made by Sylvania. Is there a 312 code anywhere?

[AcornHouse]

I couldn't find any other markings other than on the glass. On one of them, there is a bare remnants of some white markings that look like it might have included "ao".

Btw, the Dumont label and codes might be red rather than orange. (different light) Does that indicate age?

[Rupe]

I have a bunch of Dumont 12AX7s...I always wondered who the manufacturer was

[cap47]

Clear Pictures would help!

[Timbre Wolf]

Post photos - it will help immensely to see the insides of the tube(s) in question.

- Thom

[AcornHouse]

I'll try to post pics tomorrow.

[AcornHouse]

Here are a couple of pics of the tubes.
http://img444.imageshack.us/img444/2748/dumontclose.jpg (http://imageshack.us/photo/my-images/444/dumontclose.jpg/)

Uploaded with ImageShack.us (http://imageshack.us)

http://img827.imageshack.us/img827/4049/dumontpair.jpg (http://imageshack.us/photo/my-images/827/dumontpair.jpg/)

Uploaded with ImageShack.us (http://imageshack.us)

Hopefully you can see enough detail.

[Timbre Wolf]

Hopefully you can see enough detail.

:D

Yes - that's plenty big and clear enough to see the flying-saucer getter sources.

- T

[Timbre Wolf]

Flying-saucer indicates:

http://foolamak.com/fooie/wp-content/uploads/2008/10/bond02a.jpg

Those Russian-made "6L6" were often sold as 6L6G or 6L6GB, and probably won't take the same power that 6L6GC would. During the Cold War (1980 production date), those were not directly available from the Eastern Bloc, but they probably went through Gt. Britain to make their way to the US.

Funny that the schematic for the Guild 99J shows a "6L6GT" for power. I'm not aware of any 6L6GT in 1960, or any other time, except Visseaux (made in France), who made a straight-sided glass 6L6G - and it looked almost exactly the same as the Russian version you've got in your photos. The French Visseaux has a base that is only as wide as the glass, not wider. And, of course, it does not have the flying saucer getter source.

You might consider trying original Tung-Sol 5881 with that amp - I think they might work well, and would sound pretty darned good.

- Thom

[AcornHouse]

Hmm. I've asked the same questions over on the Guild forum, and one post interpreted the codes as:
Well, the "E.R.P." stands for "Emerson Radio and Phonograph", who purchased portions of Dumont's manufacturing and selected use of the name in 1958, lasting only until later in the 1960s in that format. (I read this at the metroamp forum)
60-22 is the datecode: 1960 22nd week, which also matches what I said about ERP.
The only thing I am not sure about is the 171A. It appears on other Dumont tubes as late as 1978 as well.
First I thought it would be the original manufacturer code but can't find a 171. Indeed some pages (questionable) list 171 as EIA code for Dumont (which had 158 officially), but with the A at the end?
Would Dumont have been importing Russian tubes in 1960? The date lines up with the age of the amp, making these the original tubes.

[slider313]

Hmm. I've asked the same questions over on the Guild forum, and one post interpreted the codes as:

Would Dumont have been importing Russian tubes in 1960? The date lines up with the age of the amp, making these the original tubes.

Those tubes are indeed Russian tubes from the early 80's. I've seen them with RCA and Sylvania labels also. Also, there's no way those tubes were original equipment in any amp from the 1960's.

[Timbre Wolf]

Would Dumont have been importing Russian tubes in 1960? The date lines up with the age of the amp, making these the original tubes.
The date code is from 1980, not 1960. No US company would have been importing directly from the Soviet Union in 1960 or 1980 due to Cold War trade embargoes. But that did not stop US companies from buying the same items from British companies that imported direct from USSR.

FWIW, I am unquestionably certain that those tubes are Russian-made. It helps to look inside the tube, and not get distracted by the paint on the surface.

- T

[5992]

That tube looks like a generic Russian 6P3S:

http://tubes-store.com/images/6p3s.jpg

These are equivalent to the western metal 6L6 and 6L6G, about a 19W tube, IIRC.

I believe that Groove Tubes relabeled this tube and sold it as a 6V6 replacement back in the 90s when there were no good 6V6 tubes being made.

[AcornHouse]

That makes me feel better about replacing them, then.

[slider313]

That tube looks like a generic Russian 6P3S:

These are equivalent to the western metal 6L6 and 6L6G, about a 19W tube, IIRC.

I believe that Groove Tubes relabeled this tube and sold it as a 6V6 replacement back in the 90s when there were no good 6V6 tubes being made.


Exactly. I believe Groove Tubes called them a 6V6 HD; which was supposed to mean "Heavy Duty".

[Timbre Wolf]

That makes me feel better about replacing them, then.
Replace away... you'll only improve durability and sound.

- T

[gtrgeek335]

Hey T- wolf,not to derail the thread,but I have a couple of Dumont 7025's in a couple of amps,(not here at the moment or I would post photos), I assume are re-labels,any ideas?

Gordon

[Timbre Wolf]

Hey T- wolf,not to derail the thread,but I have a couple of Dumont 7025's in a couple of amps,(not here at the moment or I would post photos), I assume are re-labels,any ideas?

Gordon

They're definitely re-labels. You can PM me the photos, if you want to avoid de-railing, and I can help you i.d. the origin.

- T

[Prairie Dawg]

They're not bad tubes, by the way.

Allen Dumont was a radio engineer who developed the magic eye tube, mostly used as a tuning indicator and also in bridge circuits. He sold the rights for enough to set up on his own building televisions and test equipment. He later sold out to Emerson.

http://en.wikipedia.org/wiki/Allen_B._DuMont

[AcornHouse]

Hey T- wolf,not to derail the thread,but I have a couple of Dumont 7025's in a couple of amps,(not here at the moment or I would post photos), I assume are re-labels,any ideas?

Gordon

I don't think it would derail. I got the answer on my Dumonts, might as well keep the thread going for others, since almost any Dumont tube is going to be a rebrand.

Enjoy!:aok

[gtrgeek335]

Thanks guys! When I get to rehearsal,I will pull them and get some photos ( note to self,don't forget!).

Gordon