Who Made These Tubes?

[Chappy]

I acquired some NOS tubes at a TV repair shop recently. Can anyone identify which English company could have made these? I can't find any date or company codes on the tubes that I can identify.

The RCA 6BQ5's say "6BQ5" and "Made In England" across the top. Underneath RCA it says "XM" and on the side of the tubes and cartons it says QF. I'm guessing thats the date code.

The Sylvania tubes say "TN 12AX7A 7025A" and "Made In England". Both the tubes and the cartons have "QG" on them.

Are there any structural clues that can pinpoint their origins?


Chappy

[Chappy]

Bump

[Dana-L]

I'm not sure who made the 12AX7's but the flying saucer-like getters on the EL84's would indicate they were made by Sovtek.

Cheers,

-Dana

[clobo]

Hi,

I don't know about the power tubes, but I do have many old 12AX7's with same plate construction (I call them ). Mine bear various brand names (Mullard, Philips, Rogers, Sylvania, Westinghouse, Magnavox, Philco, Raytheon, CGE. Also they are made in different countries (England, Germany, Canade, USA, Japan).

I find these have the same voicing (creamy, hi gain, low microphonics), and prefer them in either tweed/brown Fender, or Marshall style designs.

----see update-----I also have another variety (long, smooth, black, plates), that sound best in BF/SF Fender designs (articulate, lower gain, slight musical microphonics).----see update-----

Claude

-----update-----
Just after writing this, I decided it was time to experiment again with tube selection in the BF Fenders. Reason is, lately I've been upgrading the speakers. My Vibrolux-Reverb now has 2 matched Chicago Jensen C10N's (1967), and my son's Super-Reverb now has 4 matched CTS Alnico (1969).

Well to make a short stoty, I now use the same preamps everywhere (Mullard style), and also changed the TAD big bottle 6L6's, for RCA Black-Plates. I now find previous tube only masked the poor speakers, not needed anymore.

Claude

[kuliko]

The 6BQ5's are Russian (Reflektor Factory - where current Sovteks are made).

The 12AX7's are Brimar or Mullard. Can't tell for sure...

[Chappy]

How did russian tubes wind up available in Canada in RCA boxes with "Made In England" written on them? The QF code that is on the tubes is also on the box. These tubes were pulled out of the basement of a TV repair shop. They were in an amongst a bunch of other tubes that looked like they had been there a while? I just checked a picture of some Reflector tubes on Ebay and they sure do look like the Reflector tubes . Here is the link

http://cgi.ebay.com/EL84-6BQ5-NOS-REFLE ... dZViewItem

Is it possible that Western companies were buying Russian tubes before, or just after the Berlin wall came down? I'm confused.

Chappy

[zaphod_phil]

It would be interesting to see if the 12AX7s have a Philips or Mullard production code etched on the glass near the base.

[kuliko]

Is it possible that Western companies were buying Russian tubes before, or just after the Berlin wall came down? I'm confused.

Chappy

Yes, as incredible as it might seem, Western companies did that. Look at this:

http://cgi.ebay.com/EL34-Quad-Siemens-G ... dZViewItem

These are EL34's made by RFT in the former East Germany and rebranded by National (a US company) in 1987 (before the iron curtain came down) for the US military!!

[Chappy]

Zaphod

There are no codes etched onto the 12Ax7's. I looked at some Brimars on sale for Ebay and it looks like that's what they might be.

[Chappy]

Kuliko

Thanks for the info. It looks like RCA was doing the same thing. I really had thought I had stumbled onto some Mullards or Brimars in an RCA disguise. At least the 12ax7's look like the real deal.

Chappy

[clobo]

It looks like RCA was doing the same thing. I really had thought I had stumbled onto some Mullards or Brimars in an RCA disguise. At least the 12ax7's look like the real deal.

Speaking of odd RCA branded tubes, I also have various RCA branded EL-34's, some Mullard with typical xf* code, then some Siemens/RFT with typical thin bottle, and finally some "made in Japan" that look like my Mullards but have a ribbed plate. To make things further complicated, some of my Mullards EL34's are actually Philips or Sylvaina branded, while some of my Japaneese EL34's are actually Westinghouse or Sylvania branded. Here I'm only talking about identical tubes, bearing the same scratches on plate.

Even strangest are my boxes marked STC 12AT7WA's (Scientific Tube Company, Montreal Canada). The tubes are made in usa RCA branded blackplates, bearing JRC (Japaneese ?).

Finally I also have identical RCA blackplates (power and preamps) bearing either RCA, Sivertone, Philco, Electrohome, and International servicemaster.

With all that confusion on brands, I match my vintage tubes like this
- regroup tubes with similar construction (don't care for the brand)
- burn them up, hammer test, reject the unstable ones
- match power tubes within the batch for closest idle current
- listen to preamps, lowest microphonics/noise go in first position

Claude

[kuliko]

Rebranding has been (and is) commonplace with tubes. Nowadays you can find, for example, the same Chinese Shuguang 12AX7 branded as Groove Tubes, TAD (Tube Amp Doctor), Ruby, Mesa Boogie, Fender, ... Ironically, you won't find this tube with the Shuguang brand on it

[rjgtr]

Rebranding has been (and is) commonplace with tubes. Nowadays you can find, for example, the same Chinese Shuguang 12AX7 branded as Groove Tubes, TAD (Tube Amp Doctor), Ruby, Mesa Boogie, Fender, ... Ironically, you won't find this tube with the Shuguang brand on it

Well Shuguang just puts "12AX7" on the tubes. In my experience, getting Shuguangs from the tester/rebranders doesn't really matter. I just get them from Tubestore or similar. They are very reliable, but can sound shrill in bright amps. Strangely enough, getting the Groove Tubes GT12ax7-M from testers is almost mandatory. Ei's doesn't matter. They sound good but most of them go microphonic in guitar amps.