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NOS MULLARD EL34 6CA7 MATCHED QUAD DUAL HALO BLACKBURN XF2 labelled for SIEMENS & HALSKE, of MUNICH, WEST GERMANY!
VERY DIFFICULT TO FIND: Almost impossible today!
4 x NOS EL84's within a Matched Quad, with NICE lettering still visible, ALL with the same inner Double Halo "OO" getters and original boxes. Sometimes it takes 20 to 40 tubes tested to find this quality of matching and identical inner construction, in N.O.S. that tests above 110% mA!
The Legendary 1960's EL34 "Xf2" by Mullard, Blackburn, U.K.
The World's most musical EL34 tube known for it's pronounced liquid midrange.
Amplitrex Digital tested and plate matched for your musical pleasure
Selected for Uniquely Matched Plate-Resistance (Rp) & Tube-Gain (Mu)!
..." This tube is known for excellent performance, incredible bottom end, pronounced liquid midrange, outstanding highs. Described as the most musical sounding EL34 in the world, one of the most rugged longest lasting EL34's ever made, recently imitated but never equaled, clean, and powerful. These 1960's legends have a super polished and quite refined bass, midrange, top end. A Major improvement over other 6CA7's. Get rid of those Chinese or Russian 6CA7's and UPGRADE to original Mullard U.K. power tubes - which are Superior by far to Svetlana or Sovtek re-issue EL34's"...
PRICE IS FOR 4 BALANCED & MATCHED TUBES (QUAD) Mullard EL34 Xf2 Matched QUAD BEAUTIFUL "SIEMENS" LOGO TUBES AVAILABLE
MATCHED QUAD with Double "OO" Getters TUBE MUSEUM QUALITY STRONG LEGENDARY BLACKBURN U.K. POWER TUBES
LOW-NOISE - BEAUTIFUL SOUNDING - 1960's RARE MADE IN U.K. AUDIO TUBE QUAD (4 TUBES ) of the Rare Mullard U.K. Blackburn Xf2 Production, with 2-Getters per tube! Very Compelling Musical Tone with Long 10,000 Hour Heater Life!
These twin top-mica shields are designed to "deflect" unwanted electron bombardment to prevent cathode-poisioning. They work as a deflector-shield and help the tube achieve its correct operation point and last longer and operate cooler.
Recommended for:
Conrad Johnson
Dynaco ST-70
Vox
Park
HiWatt
Matchless
Marshall JTM combo 50 watts 1978
Marshall "Plexi"
Fender Amps
Musicman
These tubes are "PROFESSIONAL SPECIAL QUALITY" Premium Quality Amplitrex Digitally Tested Audio tubes
Authentic Mullard el34 Xf2 MADE in the U.K. in the 1960's
Factory Codes Xf2 Bxxx and Xf2 Bxxx
Beautiful old-world construction WORLDS SUPERIOR TO NEWER MADE CHINESE OR RUSSIAN TUBES in electrical conductivity.
TEST RESULTS Specification @ Real World Operating Voltage of 450 Volts:
Testing 45.7.2mA , 45,6mA, 44,9mA & 44,0mA (115%, 114%, 112%, & 110%) emissions.
Xf2 Bxxx Testing HIGH mA emissions.
Most NOS 6CA7 test between 85%-90% in GM right from the Factory
It's the mA emissions that REALLY MATTER in a EL34/6CA7
THESE TEST: 6,970, 6,950, 6,800, & 6,780.GM (158%,157%, 154%, & 153%)
All Tubes Tested on Amplitrex AT1000 DIGITAL ELECTRON TUBE TEST SYSTEM @ 450V REAL WORLD POWER!
TubeMuseum tested tubes takes the guesswork out of the process of selection delivering you the best Audio tubes that there possibly can be.
Beautiful QUAD Balanced & Matched QUAD @ fixed bias mode @ 450 VOLTS!
CERTIFIED ULTRA-LOW NOISE TOP-GRADE
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