NV(T)D, EL34 content

SG John

SG John

Ambassador of Cool Guitars and Amps.
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Over the years, Java and I have kept in touch, and always try to get together for pints of proper cask bitter whenever I’m in England, and I’ve even stayed at his place near Shannon, Ireland. One of the things we always do is send links to each other regarding eBay sales. That is how I got a pair of Goodman’s Audiom 60 speakers in my DST-30.
So, as usual we’ve been buying stuff and having it shipped to each other’s house to do away with the insane shipping costs between the Rebel Colonies and the U.K.
As I was delivering some nice NOS Sylvania and RCA 5879 valves/tubes, he had a great find waiting for me. Late one night, I received a text saying “ buy at least one of these sets.” It was a link for two very tightly spec’d quads of “unbranded” Mullard EL-34 tubes that came straight from the factory. Since Brian is never wrong on this stuff, and wanted me to use them for my ‘72 Hiwatt DR-103 in order to get rid of the bias mod, I bought both sets.
Hopefully, I will soon have the time to undo the mods, return it to stock, and throw one of these sets in. the other is for insurance, for now.

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Nice. XF4 Mullards will last so, so much longer than any current production EL34's & sound much better as well. I just recently scored a very closely matched duet of Philips Miniwatt branded Blackburn Mullard xf2 EL34's (with matching date codes) in original boxes for my upcoming JTM50 Black Flag build. Also another four Blackburn Mullard 163 series 12AX7's. Can't beat old glass. Cheers
Edit: For anyone interested in deciphering the Mullard date code shown on the tube above, it is as follows.
First character (letter) shows "place" of manufacture,
B = Blackburn,
G = Fleetwood,
J = Tottenham,
R = Mitcham,
X, Y, or + = Sittart, Holland.

Second character (numeral) shows last digit of year produced, in this case the "0" shows 1980.

Third character (letter, A ~ L) shows month produced (A = January, L = December).

Fourth character (numeral) shows week of the month produced.

So the code "B0E4" shows the tube was produced in the Blackburn plant on the 4th week of May 1980.

The color of the Mullard EL34 "base" also is an indicator of when the tube was manufactured. The "double halo" getter xf2 EL34's produced up to '69 have the brown base. The "single halo" getter xf2 EL34's manufactured from 1970 on (& subsequent xf3 & xf4's) have the black base.
Cheers
 
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Here's the Philips Miniwatt xf2 duet I recently purchasedWP_20190301_19_34_39_Smart.jpgWP_20190301_19_36_02_Smart.jpg
The codes "B2J3" show these two EL34's were manufactured at the Blackburn plant in the 3rd week of September 1972. The valve on the right has the branding on the other side (same writing as the one on the left). These are the "single halo" getter valves. The "halo" getter can just be made out inside the glass up under the silver getter flashing. Note that the plate seams are spot welded rather than crimped. The 1950's era (metal base) xf1 & all xf2 EL34's featured spot welded plates, the later xf3 & XF4 valves had crimped plates, though they are still fantastic valves of typical Mullard quality. The xf2's were produced up until the end of 1973. Oh, BTW, if anyone does come across any of the metal base xf1 EL34's, they are the ones I misplaced & their return would be GREATLY appreciated. Cheers
 
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SG John said:
Over the years, Java and I have kept in touch, and always try to get together for pints of proper cask bitter whenever I’m in England, and I’ve even stayed at his place near Shannon, Ireland. One of the things we always do is send links to each other regarding eBay sales. That is how I got a pair of Goodman’s Audiom 60 speakers in my DST-30.
So, as usual we’ve been buying stuff and having it shipped to each other’s house to do away with the insane shipping costs between the Rebel Colonies and the U.K.
As I was delivering some nice NOS Sylvania and RCA 5879 valves/tubes, he had a great find waiting for me. Late one night, I received a text saying “ buy at least one of these sets.” It was a link for two very tightly spec’d quads of “unbranded” Mullard EL-34 tubes that came straight from the factory. Since Brian is never wrong on this stuff, and wanted me to use them for my ‘72 Hiwatt DR-103 in order to get rid of the bias mod, I bought both sets.
Hopefully, I will soon have the time to undo the mods, return it to stock, and throw one of these sets in. the other is for insurance, for now.

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Wow! These are like the Holy Grails... (y)
 
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