From postmaste–(at)–riodeel.com Wed Dec 17 12:44:55 CST 1997
Article: 48383 of rec.audio.tubes
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From: postmasterspameate–(at)–riodeel.com (Ned Carlson)
Newsgroups: rec.audio.tubes
Subject: Re: GM (General Motors) 6V6 ???
Date: Wed, 17 Dec 1997 06:17:22 GMT
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“Jamie” wrote:

>A friend of mine stumbled across a GM 6V6. It tests great, and sounds
>fine….. Question is…. Who the hell actually made it? It is one of the
>’dark’ tubes having been internally coated with some blackish-grey powder.
>Any ideas? Also, anyone out there dying for one of these? I have no need
>for it….

Well, if there’s any numerical codes on it you can
look up the EIA/RETMA mfr code number here:
http://www.triodeel.com/eiacode.htm

At any rate, most of the GM-Delco ones I’ve seen were
RETMA code 274: RCA.

Here’s a response I gave on alt.guitar.amps ref 7591.

>>Here’s a quick ID chart (for 7591’s, at least):
>>
>>Numbers are sandblasted in glass in a “stencil”
>>(“broken letters” )pattern= GE
>>Numbers etched in glass are inside an octagon:
>>RCA. (usually)
>>Numbers are “solid” , not broken, but not in an octagon:
>>Sylvania (later, Philips ECG)
>>Numbers are solid, but underlined, usually with “Made
>>in USA” underneath the underlining: Westinghouse.
>>
>>7591 were made in Japan by Toshiba for sure, possibly
>>Hitachi as well.

BTW, same applies for 6L6’s & 6V6’s, generally.
Tungsols 6L6-GC have the number in an octagon like RCA,
but the guts look like a GE! The Tungsol 6V6’s have big
black plates, which, if you’ve ever seen one, wouldn’t be
mistaken for anything else. BTW, Tungsols RETMA code
was 322.

CBS Hytron 6V6-GT that I’ve seen have the number inside
circle on the top of the tube.

Oh, yeah, Toshiba made almost dead-on copies
of the old RCA black plate 6L6-GC, too.
Fortunately, all the ones I saw were labelled
as Toshiba made in Japan.

>>
>>
>>Ned Carlson, Triode Electronics,
>
>Thanks Ned for your info. The pair of 7591A’s that I have, have a top getter
>with the numbers on top in a grey paint to simulate etching. The numbers are
>arranged thus:
>
> 7591
> A
> USA

If it’s on the top of the tube, it’s almost certainly
Sylvania/Philips ECG.

The only GE’s I ever saw that were etched on the top were
those notorious compactrons (6K11, 6BK11, 6C10).
which you’ll hardly see unless you have an Ampeg or a
really weird Fender, or an old TV set.

If they’re solid letters, it’s a Sylvania (Philips ECG, same factory)
if they’re broken letters (look like a stencil), it’s GE.

Ned Carlson, Triode Electronics, Chicago, IL http://www.triodeel.com
Open 12:30-8 PM CT, 12:30-5 PM CT Sat Closed Wed
ph:773-871-7459 fax 773-871-7938 “where da tubes are”
Email catalogs: email our CataBot: catalo–(at)–riodeel.com