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GM70 - copper plates, matched pair

GM70 - copper plate, matched pairs
GM70 - copper plate, matched pairsGM70 - copper plate, matched pairs
Price: $200.00
Item Number: 1015
Manufacturer: Ulyanovsk

The military spec GM70 tubes in this precisely matched pair (2) have the highly desirable copper plates (The copper plate tubes are reported to sound better than the graphite plate type.) Both tubes have the Russian military OTK insignia.


GM70 tubes have a wide range of test results when purchased in random groups from bulk packaging. This pair has been selected to match each other within 10% or better under the following conditions:

The Amplitrex AT1000 tests GM70 tubes at 500vdc plate, -40vdc bias, expecting 70mA and 4200Gm. I also ran these tubes at high voltages and used the data sheet curves to establish test parameters more typical of real world circuits for this tube type: 1000vdc plate, -100vdc bias.


Price is for a matched pair and includes testing and matching service. Tubes ship in new white boxes with test results for current draw (mA) and transconductance (Gm) for each section.

Orders received
Nov 22-27 will
ship Nov 28-29

TC Tubes specializes in precision testing and matching of vintage and new production vacuum tubes for guitar & bass players, audiophiles, and DIY tube audio enthusiasts. Our website features secure payment options and fast, convenient shipping around the world.

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