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Question about used Mullards

keef

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Jan 27, 2002
Messages
5,006
A guy offers me a used pair of EL34, black base, XF2 and BCsomething stamps. No brand visible anymore on the glass, there is single halo/getter in the pics (I cannot post these).

I assume these are 70s Mullards - they are matched, were used in a Siemens 50W hi-fi amp and test 95% (whatever that means). $60 for the pair shipped.

What should you loo'/ask for when buying used old tubes, such as certain measurements? Seems like a good alternative if you can't afford NOS.
 

COSMOZMAN

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Jul 2, 2002
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The XF2 and the BCXX codes should be visible at the lower portion of the glass. These are etched in the glass, so they don't disappear over time.

The bottom alignment pin should have a hole in the center, where you can see in a picture that it is molded and not drilled.

The top glass flashing is very important. These tubes typically read "strong" just before they go. The amount of flashing is a helpful indicator of what's left. Anything under a 1/8" below the very top is pretty used.

The seller is asking about 1/3 of what they are worth- if they are real. I'd be wary.

I have noticed on the bay that most of the pairs and quads contains a fake tube that exhibits one or more of the above issues.

But doing the due dilligence in getting a real pair is worth the effort. These take an amp into tonal and harmonic places you never dreamed of! Good luck!
 
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ReWind James

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Mar 11, 2009
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Ya, that price concerns me. Is that $60 USD? Is the dealer reputable with a return policy?

"They test 95%" doesn't mean much.
 

roadrunner

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Aug 25, 2001
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The XF2 and the BCXX codes should be visible at the lower portion of the glass. These are etched in the glass, so they don't disappear over time.

The bottom alignment pin should have a hole in the center, where you can see in a picture that it is molded and not drilled.

The top glass flashing is very important. These tubes typically read "strong" just before they go. The amount of flashing is a helpful indicator of what's left. Anything under a 1/8" below the very top is pretty used.

The seller is asking about 1/3 of what they are worth- if they are real. I'd be wary.

I have noticed on the bay that most of the pairs and quads contains a fake tube that exhibits one or more of the above issues.

But doing the due dilligence in getting a real pair is worth the effort. These take an amp into tonal and harmonic places you never dreamed of! Good luck!

Absolutely excellent information and something everyone should know/learn.
Good post!:applaude
 

keef

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Jan 27, 2002
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5,006
Thanks everyone- I really don't know what to expect but for the price I am willing to take a chance.

If they are fakes or repros, so be it. Once I get them I will post some pictures.

Living in a country where many great tubes were invented (EL34, EL84) and factory made has some bearing on the availability and price. You see many Philips and Mullard (a subsidiary of Philips) tubes being offered here for prices that are lower than on the international market.

Here's the (pulled) ad:
http://webcache.googleusercontent.c...+"Te+koop+2+X+el+34"&cd=1&hl=nl&ct=clnk&gl=nl
 
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dtw576

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Feb 23, 2003
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Those look like XF2's for sure, welded plates and single halo, and I can see the etched date codes. The flashing is getting on the upper end of well used. If you don't play for lots of hours, those could last you a few years. If you gig a couple of times a week, you may get 6 months out of them. Or they could fail tomorrow. They don't look to have been overheated which is good as you do see that, from poor biasing, on many tubes out there. Good luck. I'd probably try them for $60 just so that you can hear what real Mullards sound like.
 

jambo

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Joined
Jul 15, 2001
Messages
120
A guy offers me a used pair of EL34, black base, XF2 and BCsomething stamps. No brand visible anymore on the glass, there is single halo/getter in the pics (I cannot post these).

I assume these are 70s Mullards - they are matched, were used in a Siemens 50W hi-fi amp and test 95% (whatever that means). $60 for the pair shipped.

What should you loo'/ask for when buying used old tubes, such as certain measurements? Seems like a good alternative if you can't afford NOS.

I think xf2 are '60s Mullards, not '70s. The date code says made in Blackburn, 3rd week of March 1963 or 1973. By 1973 though, the batch code would have been xf4.
 

Jeff West

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Jul 29, 2002
Messages
877
For genuine Blackburn-made EL34s, the span of Xf2s seems to be from 3/62 (anyone have an earlier one- latest Xf1s I've seen are many from 1/62, Blackburn usually had "transition periods" of up to several months, but maybe not with these) to about 8/73, going by the factory/date codes. All were welded plate. They lost pin 6 permanently starting early 1966. Transition from original dual halo to single ocurred over several months in early 1968, single ever after. Bases changed from (very) dark brown to true black at the beginning of 1970. Mid '73 saw appearance of Xf3s from Blackburn, main obvious change from '73 Xf2 was "stapled" plates on these. They were superceded in late '75 by Xf4s, which lost some of the teeth on the micas, otherwise still single halo, black bases, stapled plates, through the rest of the '70s. Always interested in possible exceptions, but I think the above proves pretty solid.
 

keef

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Jan 27, 2002
Messages
5,006
Those look like XF2's for sure, welded plates and single halo, and I can see the etched date codes. The flashing is getting on the upper end of well used.

Thanks much DTW - can you explain me more about how to evaluate the flashing? I don't get what it is and what I should look for.

I do have a '74 50W 1987 with Mullards and thought I could use these as spares. All my amps are in storage, since I haven't played in a band for years.
 

sickboy79

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Apr 2, 2002
Messages
5,161
The XF2 and the BCXX codes should be visible at the lower portion of the glass. These are etched in the glass, so they don't disappear over time.

The bottom alignment pin should have a hole in the center, where you can see in a picture that it is molded and not drilled.

The top glass flashing is very important. These tubes typically read "strong" just before they go. The amount of flashing is a helpful indicator of what's left. Anything under a 1/8" below the very top is pretty used.

The seller is asking about 1/3 of what they are worth- if they are real. I'd be wary.

I have noticed on the bay that most of the pairs and quads contains a fake tube that exhibits one or more of the above issues.

But doing the due dilligence in getting a real pair is worth the effort. These take an amp into tonal and harmonic places you never dreamed of! Good luck!

Another +!. That said - for $60, I'd roll the dice if they look right with the codes.
 

jcs

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Joined
Oct 31, 2001
Messages
2,106
Take a look at the silver flashing by holding the tube up at a light, if it appears thin and easy to see light thru it is getting worn, you cant always go by the size of the flashing as it varies widely..

I've seen new flashing that was quite small in area (but thick and not easy to see light thru) as well as flashing that was over quite a wide area that appeared to be good until you looked at it thru light and it appears thinner.

Comparing apples to apples is more accurate (same tubes)

Also look for burn marks on the plates of the tubes
(common on used EL84).
 

ptrickamp222

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Aug 22, 2007
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Look on the net for the Blackburn codes. Also Emission testing mean's nothing. Gm or Transconductunce test are of the amplification factor. Ask what he tested the tubes with...........And Mullard's if biased correctly will last a long time and are well worth it. That's all I use in my Marshall's. Xf2's w/ double getters, welded plates. Xf3's are the same with stamped plates....still a great tube. 5mA off are of no big deal for a matched pair. that's what I use now. A little mismatch for harmonic's and overtone's. Use to have to have everything perfect.......not no more. And Labels mean nothing, just the Blackburn codes! and flashing. Do your homework:salude
 

dtw576

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Feb 23, 2003
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Thanks much DTW - can you explain me more about how to evaluate the flashing? I don't get what it is and what I should look for.

I do have a '74 50W 1987 with Mullards and thought I could use these as spares. All my amps are in storage, since I haven't played in a band for years.
As said in a previous post, look to see if the flashing is thin and transparent. Also it should still be silver not black for a good power tube, although I've had black flashing in Mullard preamp tubes that sounded great and still work just fine. But in general, the thicker silver flashing that extends down the side of the tube is good. Most new or very slightly used Mullard power tubes have flashing that extends about 1 inch, 2.54 centimeters, down the side of the tube. The flashing on those particular tubes is well up towards the top which indicates there are some significant hours on those tubes. But I've had some with similar flashing last for years if not used constantly and biased correctly. Even brand new tubes, biased correctly, can give it up at any time. Predicting remaining life on any tube by its appearance, unless its flashing is gone and the plates are burned, is a guess at best.
 

dtw576

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Feb 23, 2003
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Those appear more "used" than the last pair just looking at the flashing. It is darker and a bit more burned off on the right tube of the pair. The brown base is just the color of the plastic base and XF1's and some earlier XF2's had brown instead of black plastic for the base material. The plates don't look particularly burned. These may last for 200 - 300 hours or more, or less. Hard to say but you don't sound like you will be running them flat out for long periods anyway.
 

TBR623

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Dec 5, 2001
Messages
555
I have not received the first pair yet, but took a chance on another pair of factory matched Mullards with boxes for $85 - double getter, brown base (whatever that means), which allegedly test better than new....FWIW. If one of these sets will be fine I guess I can't complain.

http://audio-tv-foto.marktplaats.nl...d-xf2-dual-getter-brown-base-el34-buizen.html

If you compare them to new xf2's you'll see a difference in the flashing. Here is a NEW quad of NOS xf2's, single getter
4mules.jpg
-here is a close up of the getter flashing on a NEW tube.
mule1.jpg
and the etched codes
mule3.jpg
Mullard Blackburn factory. Made in the second week of August 1969 (IIRC) All 4 of these tubes are matched within 4ma.- I've had them for 15 years.Hi-Fi tube amps guys would pay $1K for a matched quad. Rock bottom price for legit NOS xf2's is AT LEAST $300/pair. Decent used tubes for 1/2 that. IF they aren't DOA-enjoy them. Anyone that says current production tubes sound as good as xf2's,simply haven't heard xf2's. I hope it works out for you.
 
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TBR623

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Dec 5, 2001
Messages
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Ya, that price concerns me. Is that $60 USD? Is the dealer reputable with a return policy?

"They test 95%" doesn't mean much.

A return policy on NOS POWER Tubes? Highly unlikely. Most will ship and IF they turn up DOA the blame goes to the shipper. I don't sell tubes anymore-but when I did NO RETURNS-you can toast a pair of ANY power tubes-and if I didn't personally install them-no way would I accept them back.

Unless they are tested on a Maxi-matcher or similar tester(which would put 400v on the plates and biased at -36v and the current noted on the box) the old TV style tube testers don't give accurate readings-they just don't put enough voltage on the tube. NO WAY would I expect a $60 pair of Mullards to have very much life left.
 
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keef

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Jan 27, 2002
Messages
5,006
Thanks much everyone. I hope the crap shoot works out...
 

humbucking

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Jun 5, 2002
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A return policy on NOS POWER Tubes? Highly unlikely. Most will ship and IF they turn up DOA the blame goes to the shipper. I don't sell tubes anymore-but when I did NO RETURNS-you can toast a pair of ANY power tubes-and if I didn't personally install them-no way would I accept them back.

Unless they are tested on a Maxi-matcher or similar tester(which would put 400v on the plates and biased at -36v and the current noted on the box) the old TV style tube testers don't give accurate readings-they just don't put enough voltage on the tube. NO WAY would I expect a $60 pair of Mullards to have very much life left.

I know three tube dealers who offer a return policy on NOS tubes. Straight up guys who know their shit! They charge full price, but you get what you pay for!
 

bluesforstevie

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Jun 20, 2002
Messages
12,771
A guy offers me a used pair of EL34, black base, XF2 and BCsomething stamps. No brand visible anymore on the glass, there is single halo/getter in the pics (I cannot post these).

I assume these are 70s Mullards - they are matched, were used in a Siemens 50W hi-fi amp and test 95% (whatever that means). $60 for the pair shipped.

What should you loo'/ask for when buying used old tubes, such as certain measurements? Seems like a good alternative if you can't afford NOS.

The thing about used tubes is that you don't know how they've been treated or mistreated for that matter. They can be a very good deal, or they could quit the next day....you know? That is much less likely to happen with NOS. But, if you do buy used old stock tubes....ask the seller if he's got a tester, what they test on the "life test". Most good tube testers have a dropped voltage test that tests the strength of the tube with a voltage that is lower than normal. This is a good test that can predict the future "life" of the tube.
 
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