The JJ EF806S took several years to develop. Love 'em, need 'em, they'll drive you nuts. EF86's are extremely high gain Pentodes that first saw action back in the 50's and famously with Vox in the 60's. Even back then they were pesky buggers and phased out ASAP. Fast forward to present time and players have rediscovered the magic of overdriven Pentodes. We have a multi-tiered noise/microphonics test for these tubes. In most cases all of our standard offerings will be quiet and stable right out of the box. In combo amps we highly recommend using one of our EuroDampers. For extreme applications contact us.
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. If a tube does not pass our strict performance criteria it's tossed or sent back to JJ Electronic for evaluation.