Tube Lab  

If a specific tube is noisy, just turn your system on as per normal, set the listening volume to regular, PAUSE your music and place your ear close to your tweeter (Caution! Make sure no one will touch play or change the volume). If the tube is noisy, you'll hear it clearly above your normal noise floor. We have a custom built preamp and headphone amp that we use to listen to all of our preamp tubes that we sell. Listening on headphones is the best, you hear everything! All tubes introduce a tiny amount of distortion, but excessive distortion will be readily heard when you are playing a good clean reference recording (something you are familiar with). I would note excessive distortion is very rare in tubes and noise is very common, particularly with used tubes.

Note that often when a tube is harmonic in circuit it is often the circuit that's to blame - a lot of really badly designed tube amps have been hitting the market in the last year or so. Now all tubes are harmonic, but excessive ringing is not normal and sometimes it's just a badly made or a damaged tube that just needs to be chucked.

@@tubelab194I have had several 6n1p tubes supplied by the manufacturer where ticking is heard through the speakers when the volume is turned up. As you know the Freya has a resistive ladder volume. Switching European USA or Japanese tubes resolved this issue

@@sopasadena1499 Normally the 6N1P isn't a microphonic tube, and IMO is one of the great undiscovered preamp tubes still available for reasonable money. We have a project in development that will make use of it. Now I'm talking about the mil spec version, which has an "ev" attached to it's tube number, which indicates it's a vibration resistant tube. The standard version sounds great, but isn't built nearly as well as the EV version. And of course what you're hearing are microphonics, which may be the tube or the circuit causing the tube to become microphonic.

Its a GE manufactured 6GU7. The defining features are the side holes on tall grey ladder plates and a top filament bridge. Great sounding tubes!