Mullard vacuum tubes

CV4004 / M8137 / 12AX7

129.00 USD

 Top quality double triode audio amplifiers manufactured by Mullard in England. These fine 9 pin miniature glass tubes come with gray plates, heavy mica spacers, and top getters. They are printed in white with Mullard logo, M8137 MADE IN GREAT BRITAIN, and some may also be coded in white with War Department arrow CV4004 KB/D or other codes.  

Condition

Tube Matching
Tube Matching
6.00 USD by tube

WHY ?

A tube may have one, two, or three internal sections depending on the purpose of the tube; somtimes these sections are all the same, sometimes they are different. Due to manufacturing and material tolerances, there may be slight differences between the original specification and the actual tube. Tube matching tests each one of these internal sections and selects tubes, compared to original specifications at manufacture, for balanced performance and good sound.

HOW ?

All our tubes are tested by us prior to packing on our Stark, AVO, Simpson or RF Laboratories Inc. calibrated testers. On request for tube matching, tubes are matched for Mutual Conductance in Micromhos and Plate Current in Milliamps on our Amplitrex or Radioelec Duovac testers, with results printed for each  individual tube. Certain tubes difficult to test are matched for Mutual Conductance in Micromhos only on one of our regular calibrated testers. On request we can also test for Microphonics.

Quantity
Product available with different options

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Data sheet

Base
9 pin miniature Noval B9A
Boite type
1/7
Emplacement
SS
Quide
277
Fonction
Double triode
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