All our preamp tubes are stringently tested for noise and microphonics using Amplitrex testers driving an external amp. There is no extra charge for low noise and microphonics testing like with other tube vendors. Additionally the tubes undergo a battery of tests for basic performance characteristics and faults such as: Emissions, Transconductance, H-K and Grid leakage, etc...
Further, all of our ECC82's undergo a lengthened test duration to insure stability and accurate test results (as is necessary with all high current pre's).
If a tube does not pass our strict performance criteria it's tossed or sent back to JJ Electronic for evaluation.
The JJ ECC82's are true to spec examples of the classic 12AU7. These use JJ's short plate design which makes them very resilient to microphonics and mechanical noise.
For most standard driver applications (reverb and FX loops for example) our standard selection is suitable. For stereo or parallel driver applications refer to our matched triode and current balanced selections.