Early '90s tripple mica Beijing Chinese Military high gain 12AX7's

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by LPVM, Feb 2, 2015.

  1. LPVM

    LPVM Member

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    It's funny how I sometimes read something that alerts me to stuff that I have in my stash that I discounted as crap decades ago and never even tried. I was reading a write up on the Amp Garage about preamp tubes and the author had included a write up on the 80‘s/90‘s Beijing Chinese Military Square Getter Triple-Mica 12AX7 . He went into some detail about them and said "these older production tubes sound nothing like the newer mass-produced Chinese Shuguang 12AX7s, which can have a very harsh and unmusical tone". These are the famed early '90s tubes Marshall and Mesa used that a lot of guys like. Anyway, I got a new piece of gear back in the early '90s that had the 12AX7A in it which I promptly ripped out and replaced. It's been sitting in my tube bin since.

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    I also acquired 40 NIB National branded 5751 tubes a year and a half or so ago from a customer of mine.

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    They used them as spare parts in old equipment but had not used any in many years so they ended up in a list of parts they were looking to liquidate. When I saw them on the list I was dreaming of finding a big score of vintage glass but when I pulled their purchasing records I saw that they were part of a 50 pc buy they did in 1993. They still had all 50 but wanted to keep 10 just in case they needed a few. I had a few of them tested on a high end computerized tester and the test results indicated that they are high gain 12AX7's that were likely just labeled as 5751's.

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    I sold off most of that lot to a popular tube dealer and traded some with dudes on forums. I had tried them in a few of my amps and didn't really like them in the amps I tested them in so I didn't really care to hold onto many but kept a sleeve for utility use. Anyway, I was just comparing one of those with this Beijing tube and I'll be damned if it isn't identical in every way.

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    I had previously only tried them in medium to low gain amps and have since acquired a Peavey 6505+ and decided to give them a try in a high gain amp. I pulled vintage Mullards I had in V1 & V2 and stuck in the Chinese glass. At first I thought, not much difference....why waste the mules, I'll leave these in. Then I cranked it.

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    HOLY SMOKES!!! Now I know why guys love these in high gain amps.

    Here is a short low volume clip recorded with a cell phone. The amp was set to the red channel with the gain at 3. I went straight in with a Les Paul Standard and had a Digitech DL8 set to loop and a Hall of Fame reverb in the EFX loop. It's a BEAST when you crank it. I haven't had a chance to mic it up and record a clip of that yet but plan to later this week.

     
    Last edited: Feb 2, 2015
  2. J M Fahey

    J M Fahey Member

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    Nice discovery :)

    Doubly so because you already had them :eek:
     
  3. DGDGBD

    DGDGBD Member

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    I bought a bunch of those chinese 12AX7s in the 90s (labeled Ruby) because they were cheap and had a rep as being very quiet.

    I recently realized that my old Groove Tube labeled 12AX7s that I bought in the mid-80s were actually made by Tungsram. They sound fantastic in my '68 Bassmaster YBA-1.
     

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