Did Mullard ever make 6l6?

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Postby jcs on Mon Mar 13, 2006 7:23 am

jeff, yes B7I not B71 and no hole in the guide pin of the XF1 brownbase el34...

also i observed a specific pattern on the top of the glass,plus some bits floating around inside the glass of the XF1 and the original flashing was pretty scant on this tube when observed with a magnifying glass,plus the brown-maroon base has a sort of metallic appearance under magnification...

on the metal base el34, i observe a single seam across the top of the glass and this tube has a hole in the guide pin...
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Postby voxmarfen on Tue Mar 14, 2006 3:50 pm

Metalbased 55 - 56 - 57 s , i have not one 54 or 58 , brown or black base hole in guider , one seam on top , they do also come with codesformat DD DDD : 5C SYN as opposed to DDD DDD : SY1 56G
Still digging to find out if they are Toshiba Japan (man.code = 5) , or Eindhoven Holland made or elsewhere .
Valvo and RT and Standard Brand , bought them in from Philips , same codes.
Telefunken made their own EL34 metal version in Ulm Germany, crimped plates.
Smaller diameter Glass.Black base.

Jogi has a great site on EL34 , i can read and write German , i asked him to consider an English version , but no clue if that will ever be the case.
http://www.jogis-roehrenbude.de/

These are all Audiophile - camp guys , not Guitar - camp .

The EL34 was already a fact in 1949 , there are papers that mention the development from the EL60 (metal) and EL61 that are the true forerunners (identicall construction and specs.) off the EL34 to its birth in 1949.
The EL60 and EL61 are still in production at the same time as the metal EL34, fasing out in 1958.
(Similar types metalrim are 4699 , 4688 , and EL6 with the P feet/socket)

But i never saw any EL34 with datecodes between 1949 and 1954/55, it was there thow!
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Postby JeffWest on Tue Mar 14, 2006 5:22 pm

Of the '54s I have and have seen, all have black bases and incidentally some don't have the hole, although most metal base do. All of these metal base that I have seen have the faint single seam on top.

Brown bases seem to maybe have been random in '56-'57, for example I have a brown and a black metal base with same exact codes, '57 IIRC.

I have one metal base (black) that has noticably smaller original metal collar (less wide) than usual, otherwise looks the same. It's not the earliest one, has SYO and '55 stamping, I don't remember the month offhand. That is, I have both earlier and later specimens with the usual wider collar.

Yes, these (most common) metal base had lots of additional brandings, Bugle Boy, Miniwatt, Rogers, Mullard, Philips, Valvo . . . I think they're always labelled Holland FWIW.

I agree that some of the usual metal base were rebranded Valvo, but I think I've seen more than one Valvo metal base apparently made in Hamburg, with dual halo getter rings not the big flat disc (but definitely welded not Telefunken rectangular staples). It's been awhile, though.

Since the digits 1 through 7 or more (except 5) were listed as factory codes for Eindhoven, one hypothesis could be that "5" was left off the lists somehow even though it was used for Eindhoven in the '50s, then later was officially assigned to Toshiba. One thing that might bear on this would be the date of onset of official collaborations between Philips and Toshiba. Which I don't know, although I think it could have been post-'57. Dai, you out there?

Jeff
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Postby voxmarfen on Wed Mar 15, 2006 9:40 am

Here are some pics , number #1 is the EL60 direct forerunner to the EL34 code M91 58C , number #2 is the inbetween EL60 and EL34 model with high socket and EL60 plates, code is 5P KE3 (KE means,like XF and SY, EL34) , since this is the earliest , i believe that the DD DDD format is also the earliest , 5 is the manufacturer , so either Toshiba or Philips Eindhoven , and P is 1954-1956, number #3 is the only really new os EL34 metal i have seen ( i counted approx 30 today in my box ) with original box , peculiar enough the same standard brand logo (industria) and label was on ebay recently but with a RFT or similar EL34 tube. Code SY0 56G brownbase , most 1956 s are brownbase .

These are heavy tubes , 60 grams compared to 46 grams for EL60 , 52 grams for longfoot EL34 , and 40 grams for a regular Blackburn EL34.

The EL60 and the inbetween model EL34 have 4 coolerfins (instead off 2),
and round plates with ceramic white beads and thicker mica to cancel out microphonics , you can clearly see the similarities and that the EL60 is the true forerunner to the EL34 , its a direct replacement , except for the socket. The plates surface is precisely the same , althow the very early El34 has round plates , its just as large as the later EL34 s.
The EL60 is also very rare and expensive , i saw Tube World ask $1300 a pair... :?:


Image

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Free Image Host - PicTiger

PS , Valvo also did make some metal EL34 off their own , and EL60 still was around in 1958 , i never saw any El34 with 58 code.
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Postby Jerry G on Sun Apr 09, 2006 2:12 pm

Looking at this thread makes me realize how much a newbie I am when it comes to tubes and amps, but i just scored 4 Mullard EL37's and I would like to drop them into my Mojave Plexi 45 which uses the 6L6.

Do I definatly have to rebias the amp?
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Postby ozsubrosa on Mon Apr 10, 2006 12:23 am

There's a Belgian seller with a coupla metal-based Mulls I've passed on. This one is claimed to be a '56:
http://cgi.ebay.co.uk/1956-el34-mullard-metal-base-roehre-tube_W0QQitemZ6268447039QQcategoryZ65888QQssPageNameZWD2VQQrdZ1QQcmdZViewItem

and another Belgian sale:
http://cgi.ebay.co.uk/One-EL34-Mullard-metal-collar-disk-getter-used_W0QQitemZ9707312547QQcategoryZ3284QQssPageNameZWD2VQQrdZ1QQcmdZViewItem

I don't know the significance of the "SYO" code, but thought it might interest someone.

Oz
"Have bass, will valve"
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Postby The Pup on Mon Apr 10, 2006 4:10 am

voxmarfen wrote:Here are some pics , number #1 is the EL60 direct forerunner to the EL34 code M91 58C , number #2 is the inbetween EL60 and EL34 model with high socket and EL60 plates, code is 5P KE3 (KE means,like XF and SY, EL34) , since this is the earliest , i believe that the DD DDD format is also the earliest , 5 is the manufacturer , so either Toshiba or Philips Eindhoven , and P is 1954-1956, number #3 is the only really new os EL34 metal i have seen ( i counted approx 30 today in my box ) with original box , peculiar enough the same standard brand logo (industria) and label was on ebay recently but with a RFT or similar EL34 tube. Code SY0 56G brownbase , most 1956 s are brownbase .

These are heavy tubes , 60 grams compared to 46 grams for EL60 , 52 grams for longfoot EL34 , and 40 grams for a regular Blackburn EL34.

The EL60 and the inbetween model EL34 have 4 coolerfins (instead off 2),
and round plates with ceramic white beads and thicker mica to cancel out microphonics , you can clearly see the similarities and that the EL60 is the true forerunner to the EL34 , its a direct replacement , except for the socket. The plates surface is precisely the same , althow the very early El34 has round plates , its just as large as the later EL34 s.
The EL60 is also very rare and expensive , i saw Tube World ask $1300 a pair... :?:


Image

Image

Image

Free Image Host - PicTiger

PS , Valvo also did make some metal EL34 off their own , and EL60 still was around in 1958 , i never saw any El34 with 58 code.
:shock:
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Postby saros141 on Mon Apr 10, 2006 6:26 pm

JeffWest wrote:
Since the digits 1 through 7 or more (except 5) were listed as factory codes for Eindhoven, one hypothesis could be that "5" was left off the lists somehow even though it was used for Eindhoven in the '50s, then later was officially assigned to Toshiba. One thing that might bear on this would be the date of onset of official collaborations between Philips and Toshiba. Which I don't know, although I think it could have been post-'57. Dai, you out there?

Jeff


I agree, 5 was probably redesignated to Toshiba and was originally Eindhoven. I have a PDF scan of a FVAR "Indication of the Manufacturer" list, where there is actually an empty gap between 4 and 6. I have a short-mesh EF86 from March 1960 with the 5 code and Holland label.

I wonder if the Philips Eindhoven plant could have been where they tried out new designs. I have a pair of EL33 (high sensitivity pentode, very much like a low power EL37) that, if I'm reading the codes right, were made in Eindhoven in July 1948.

BTW Jeff if you ever write a book or reference website compiling esoterica on speakers, valves, caps, etc., I'll help any way I can and/or sign me up for a copy. Sorry I was no help on the transistor codes.
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Postby JeffWest on Tue Apr 11, 2006 5:30 am

Hi Damon- Yes, Theo's research subsequent to writing the above, which hopefully he won't mind me mentioning here, determined that the Toshiba/Philips connection and the awarding of the "5" to Toshiba first occurred just after your EF86 example, around '60-'61, not in the '50s when all the metal bases were stamped.

We were comparing our specimens to try to determine the difference between "SY0" and "SY1". Would appear that great majority of SY1 are brown base and SY0 black, but there are exceptions. And they are definitely not purely chronological, per the date codes, have SY0s from both before and after SY1s, etc. So . . . ?

Eindhoven was definitely Philips "ground zero" and they said they did develop the EL34 right there for example, and the earliest technical papers on them came from Eindhoven. Did I ever send you the contemporaneous Philips article about their big 60th anniversary bash at the Works there - from 1952?

JW
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Re: Did Mullard ever make 6l6?

Postby gererick on Sat Sep 21, 2013 10:04 am

I just purchased four EL-61 tubes mistakenly; I thought they were the same as EL-34 tubes but the sockets are different. On Ebay I see EL-60 to EL-34 adapters; will these also work okay as EL-61 to EL-34 adapters?
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