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Paging Jeff West: Mullard Tube Question??

bluesforstevie

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What is the deal with the Mullard Yellow Print tubes? Most of them seem to be mid 60's examples and they tend to have two initials on them as well? Any way to decode those? For instance, I've a GZ34, yellow print with the initials "M" and "H" on the either side of the BVA oval.

Is it the distributor? Where they were silkscreened? Anyway. Thanks in advance!!
 

Jeff West

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Hey Dan- I've heard info about this from various sources, inc UK Vintage Radio guys, but I'm not sure that anything is nailed down 100% certain regarding the yellow print on seemingly standard Mullards (and not counting "10M").

Having said that, I think it may likely reflect intended sales/use trajectory of the tubes. Specifically, there's evidence that the yellow labels were generally intended for OEM use in equipment and generally provided in egg crate or bulk packaging (and found as stock in equipment), whereas those valves for retail sale individually packaged would be white label. Among other things, this was apparently the understanding of numerous separate people involved in electronics and audio in Britain in the early '60s period.

Contrary to what is sometimes claimed, it clearly was not just a period of time in which they switched to yellow, you can find white and yellow with the same etch codes, etc.

There are lots of exceptions to the above claim: white label tubes seemingly original in OEM equipment, and yellow label in individual boxes that seem original, etc. The explanation is said to be that they couldn't always uphold the distinction, depending on stock on hand, and eventually abandoned it in the late '60s or before for that reason.

Incidentally, several U.S. tube manufacturers are known to have used different printed coding details in the '50s and '60s for OEM vs. retail bound tubes that were otherwise identical. These include RCA and Tung-Sol, for which period written company records on this topic exist. On RCAs it included the presence vs. absence of a "dash" in the printed date code, on T-S it included whether certain letters in "Made In USA" printing were slanted or not!

Other things that have been claimed about the Mullards include that the yellow ink reflected a different warranty. This could be true, but might actually be just another facet of the above OEM distinction, in that many tube manufacturers did have different warranties on OEM vs. retail sales, related to replacement period, etc. This also might fit with the fact that yellow label have the additional letter codes while the white do not (see below).

Interestingly, among vintage British wireless type guys, common lore seems to have been that the yellow label specimens didn't last as long, raising the suspicion that they somehow might be "seconds" (or, at least, not "firsts"). Do they get a premium or reduced price on E-bay these days?

Regarding the "side letters" surrounding BVA, these do appear to reflect the year and month that the yellow was printed, or possibly that the tube was intended to ship, and/or that the warranty period might go into effect. As such, when decoded they should fall at least a little later than the etch codes, or possibly considerably later in some cases. I have some notes which I didn't credit for source unfortunately that suggest that the letter on the left as you face the logo is the year, with J said to be 1962, K='63, L='64, M='65. Months on the right appear to fit nicely with A=Jan, B=Feb. We'd have to see if anyone's got an "M" on the right to know if they skipped "I"; probably not, going by the Philips etch code practice.

With your M and H on the GZ34 decoded as Aug '65 per the above, does that seem reasonable with the other codes on that tube? I haven't really checked the above decoding out thoroughly, it might be off.

You see the occasonal '50s made Mullard with yellow printing, possibly the above letter codes can be traced backwards to go earlier.

Anyone with more/better info please step up!

Oh, there's also this: http://www.tube-classics.de/TC/Tubes/Valvo/Philipscolors.htm

But I dunno . . . even if true it may not apply to our fave 12AX7, EL34, GZ34, etc. Also, all of those are Valvo branded. And don't have the side letters.
 
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bluesforstevie

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Wow...Looks like I paged the right guy. Thanks Jeff!!!:salude

You're right on with the initials as the date code of the "M" and "H" valve is B5H1; 1st week of Aug. 1965!!!

You're a wealth of info my friend!!
 

ADRIANA DELGADO

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Apr 18, 2019
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What is the deal with the Mullard Yellow Print tubes? Most of them seem to be mid 60's examples and they tend to have two initials on them as well? Any way to decode those? For instance, I've a GZ34, yellow print with the initials "M" and "H" on the either side of the BVA oval.

Is it the distributor? Where they were silkscreened? Anyway. Thanks in advance!!

GREETINGS, EFFECTIVELY WAS IN THE DECADE OF THE 60TH BUT THE INITIALS M AND H COME DIRECTLY FROM THE FACTORY THAT ASSEMBLIES FROM THE INITIALS OF THEIR FOUNDERS.
 

Oatie

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<style type="text/css">p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 24.0px Garamond}p.p2 {margin: 0.0px 0.0px 0.0px 0.0px; font: 24.0px Garamond; min-height: 27.0px}</style>Not to HiJack the thread,

Jeff, about what year do you think these Mullard 6V6G tubes were made? I have two sets of these and a set of GEC that look almost the same. Some say they are Marconi tubes, would be nice to know a little more. I tried a set in an old tweed Deluxe and they sound great. I use the Raytheon 6087 rectifier and 5751 in V1 and V2 and it's a magic combo.

I'm building a small dual bias pot board so I can adjust the bias on my 50 watt Marshalls for each tube. A good way to use some old stock EL34 Blackburns and match the bias with a pot for each EL34 socket. When the board is done I will share the info to the gent who builds them in a small turret board. The early JMP50 amps with the stand-up PT have plenty of room to install the dual bias pot board. The Laydown smallbox chassis will need some new stand-offs to make it work. Love the EL34 Blackburn tone.



mullard-6V6G-CloseUp.jpg



mullard-6V6G-Back-Flashing.jpg
 

ourmaninthenorth

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I wouldn't bat an eyelid if these had GEC stickers on them, and were mentioned to be from the 40's.
 

Jeff West

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Can be hard to ID some 6V6Gs especially without in-hand inspection, but my best educated guess for actual manufacturer of origin for those would be British Tungsram, 1950s.

Under other liveries (e.g. CV509), I think you'll find these with British "T" codes for Tottenham/British Tungsram, and the "up arrow" mark; unlike lots of codings/writings on tubes, those former can be considered to reflect the factory of origin accurately (unless, of course, the printing itself is counterfeit). You do see them with genuine "GEC" oval decals as well. I guess you have some of those too, Oatie?

Pretty much all the GEC 6V6GTs I have or have seen were made by either Tungsram or Brimar in UK, although I can't say that's exhaustive. Maybe some Ferrantis? I'm confident these above are not Brimars, and definitely not Canadian Marconis.

Not all British Tungsram 6V6G versions look alike, however, inside or out.

Great valves, all of the above. I really love the Brimars. The UK Tungsrams also sound great, and many look especially cool, like mini KT66s.

Btw, if you encounter "ZA 5306" on mil or other versions of British 6V6Gs like these, confusingly this does not indicate manufacture by Marconi-Osram Valve via the "ZA", nor is the "5306" a date code indicating early 1953. Rather, ZA 5306 was a govt "cross reference store number" that did not reflect a specific factory or date. However, note that some of these with that code also have additional legitimate date codes indicating 1953!

Addendum: I was looking again at those photos, and some things don’t look quite right for Tungsrams, have a few questions
 
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Oatie

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I have 2 sets of the Mullard coke bottle and 2 sets of the GEC unused. They came from an old Hong Kong gent dealer about 20 years ago.
The GEC tubes have brown boxes that look like Mil Spec writing and are packed with that old horsehair looking matting. The Mullards have the corrugated cardboard wrapped in paper inserts. I also got some great dual top getter Mullard GZ34 tubes from him with the same type logo screened. They make great tone in the tweed Deluxe. I still have a couple dozen RCA 6V6GTA tubes and they are my main tubes I use.
I like the GE or Raytheon 6087 rectifier and two 5751 in the Deluxe.


mullard.jpg
 

Jeff West

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Cool- Do The GECs look exactly like the Mullard? Anyhthing interesting stamped on the GEC boxes, or the tubes themselves for that matter?

And, if you remember, is the GZ34 f31, f32 or?
 
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Deus91

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Jeff. here are a pair of 6V6G with the "ZA 5306" lettering from my stash.
You referred to them in your earlier post.
OE9HaV2.jpg
 

Jeff West

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Yes, and those look to be British Tungsram.

JOB-LOT-OF-10-BRITISH-MADE-6V6G-BRIMAR-_57.jpg


Got any shots looking down at the tops of 'em? Thanks-
 

ourmaninthenorth

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Here's a couple of shots that lead me to believe that they're GEC's.

Note the cooling fin configuration in comparison to the Mullards.

These are not my valves..stock photos.


b9gQMtf.jpg



oJpNo44.jpg




And showing the military/government designation...


14WrTua.jpg



Fascinating stuff this isn't it?

:salude
 
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Jeff West

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Nice photos, Paul. Yes, the mini KT66, I have some just like that. I agree that the details on top are a key identifier- are you satisfied they're a match to Oatie's?

Since we've come this far, though, here's the rub about identifying the actual maker: the GEC decal is a commercial label that is not part of the gov't/mil standards marking. It could be (and was) applied by M-OV to valves sourced from other factories, valves that may have been marked re: other standards, etc. That is, the GEC decal is not specific to a factory of origin in the way that, say, a "KB/Z" coding is specific to Hammersmith/M-OV.

So, for example, I have numerous 6V6Gs that have that have virtually identical GEC decals, also R.A.F. related "10E" codes, but were clearly made by Brimar, and have Brimar S.T.C.F. markings on the base.

Here's a stock photo of a couple, although unfortunately without any other markings showing, maybe I can get some more photos up later:

a27233bcb15827ee9ca6bc2d68743f4e.jpg


So, one question is, did GEC/M-OV really make the GECs in the last photos? I believe I've seen versions of those with reliable "T' factory codes, but now it's on me to come up with proof!
 

Jeff West

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Thanks for great photos, Paul. Can be fascinating, although maybe at some points be better to just play on . . .

I did submit smething in response, but apparently waiting in the Moderator queue, hopefully will come up.
 

Jeff West

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In the meantime, some other food-for-thought photos, if they go thru:

212c.jpg

above via KCANOS; has U-shaped grid rod radiator like Oatie's appear to
To give credit to Mike at KCA as due,I believe he has already said in the past that he thought Oatie's are just like this

large_486.gif

Above resemble Paul's GEC photos? Look to have British Tungsram logos with the "Tungsram" worn off or removed

imu-media.php

This one above may have some provenance as a British Marconi product. And the codes shown could indicate a 1948 date of birth.


NOS-British-GEC-6V6G-CV509-Military-Qued-tubes.jpg

NOS-British-GEC-6V6G-CV509-Military-Qued-tubes-_57.jpg

The above are definitely "T" coded, resemble Paul's GEC photos above(?)

large_388.gif

Above we get Mullard labelling, but there are some differences from Oatie's-
 
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ourmaninthenorth

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In the meantime, some other food-for-thought photos, if they go thru:

212c.jpg

above via KCANOS; has U-shaped grid rod radiator like Oatie's appear to

large_486.gif

Above resemble Paul's GEC photos? Look to have British Tungsram logos with the "Tungsram" worn off or removed

imu-media.php

Food for thought indeed Jeff. Great research.

The Mazda I think is French made, or one of those Mazda's that Brimar had some hand in, and were British made. Simple stuff this...yeah right...:laugh2:

The quad set are equally confusing, Tungsram style half worn off logo ( a little too uniformly for my liking ) with a Haltron* type face on the 6V6G script, with GEC physical characteristics.

The third one - the picture makes the physical details hard to see, so don't know. Very early coding though. One to ponder in hand methinks.


* Haltron - not a valve manufacturer, they bought valves in from various sources and re-badged them with their own trade name.
 
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