12AV7 NOS Multi Brands RCA GE ECT 5965 12AX7 12AT7 7062 12AY7 Noise Tested

Description

New Old Stock/NEW  12AV7 Multi Brands  (see photo)  5965 12AT7 E180CC  SUB
Noise and Oscillation Tested* (See test procedure below)
12AX7 12AT7 7062 12AY7
plug-and-play substitute with lower gain.
12AV7 is used by many to lower the gain of guitar amplifiers and obtain a cleaner sound.
The trans-conductance (GM) of the 12AV7 is 8500 compared to the 12AX7s 1800
The higher transconductance of the 12AV7 leads to a more three-dimensional sound with a wider frequency response than obtainable with the 12AX7.
Many guitar amplifiers have been built with actually too much gain which leads to a nonmusical sound and harmonics that are not symmetrical.
The 12AV7 can be used to clean up and enhance the sound of many mega gain amplifiers.
When the 12AV7 is used in a circuit that was designed for a 12AX7 they gain will be higher than the design characteristics of 41, a gain of approximately 60 to 70 will be achieved (close to the gain a 5751) this is due to the higher value of plate load/cathode resistor present in the 12AX7 circuit.
(Noise test procedure)
Each tube is placed in the preamp section of 100-Watt Guitar Amp and OTL Headphone Amp.
Connected to a 4X12 speaker cabinet and (headphone amp to high-sensitivity headphones)
Test signals of 500-1K-5K and 8K are used.
If auditable noise is present or If tube oscillates and produces its own frequencies,
Sometimes referred to as (tube going into business for itself) it is rejected.
We do not insert the tubes and tap on the tubes and listen for noise.
This is not a legitimate or practical test procedure, even low noise variance of vacuum tubes
like 5751, 6922 will produce noise if subjected to this type of testing.
Therefore, we render this type of testing useless and not valid.
We test in practical real world working conditions, the conditions the tubes will be used in.
Sincerely Management.