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View Full Version : Tube Pro's,, I need some help with Mullards


recto-robbie
12-26-2007, 12:57 PM
Hello tube pro's,, recently I took a chance on ebay with two sets of Mullard 12ax7's from two different buyers. These tubes were all slightly used.
I have always assumed that Mullard preamp tubes would sound much the same.

One set I get was labeled 12ax7a/ecc83 with the mullard sign mostly wiped off and they had the etched B code.
The other set was labeled 12ax7/ecc83 with Mullard and BOGEN silk screened on them, also with B codes. And both say made in GB on them.
Both of these sets looked identical on the inside,, short plates.

After trying the two different sets I found the 12ax7a's to sound so much better. I was in complete awe and had never heard a tube sound so nice,, the best ive ever tried comparing them to the other set of Mullards and other NOS tubes I own.

Is there much difference in sound between different Mullards?
Is the Mullard 12ax7a a better known tube by Mullard?
Are long plates normally better sounding than shorts?
What do I need to look for to find those awsome sounding Mullards?

Both of the sets I listed above sounded very nice,, but the 12ax7a sounded extremeley nice. Awsome.
Id like to get a back up set of Mullards but now that ive bought two sets and found them to be very different,,, I dont know what direction to go now. Even paying a lower price for a slightly used Mullard isnt dirt cheap and I dont really want to start a crap shoot with tubes.

Any help or suggestions is greatly appreciated,,, thanks much,, Rob

rockon1
12-26-2007, 01:06 PM
Look for the full etch codes. I find the earlier short plates sound warmer-less bright even though the guts look identical. As far as short plates goes Im referring to the I61 etched ones. Heres a link that will help you identify them. Bob


http://www.tube-classics.de/TC/Tubes/Valvo/Phlipscode.htm



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Blue Strat
12-26-2007, 01:22 PM
Mullard and other European tube companies made "ECC83s", not 12AX7s (with any suffix). 12AX7 is an American tube number.

Any 12AX7/A markings on the tubes are by American re-branders (Bogen for instance). There is likely no difference between your 12AX7As and 12AX7s other than strength unless one has long plates and the other has short plates.

Even when everything is equal, tubes made on the same day in the same factory can sound slightly different.