[smcvick]

I am currently demoing an SWL 9.0SE at home, borrowed from a dealer.  When powering up the unit, once the normal 45 second warm-up period has ended and the preamp is unmuted, I hear some high pitched pinging noises through the speakers.  This only lasts for a few seconds, and is presumably the sound of the tubes coming to life, but I was wondering if this is expected behavior.  Do other SWL owners out there experience the same thing?  Dan, is this normal behavior for your preamp?

Thanks in advance for any input.

[bambadoo]

That is quite normal for 5687 tubes. It is the internal of the tubes warming up.
I have not a SWL pre, but an Audio Note balanced line stage with the same tubes and have the same behaviour.

Best Regards

[AB]

I have an SWL and mine does this as well. It's a very soft "tink, tink" which lasts only for a few seconds as the unit first comes off mute. After a few seconds it stops.

I have always considered this to be normal.

[smcvick]

Just got an email back from Dan, and everybody seems to be in agreement.  It's just the tubes warming up, and this is perfectly normal.

[bambadoo]

I really like that sound.  Like something is making itself ready to please me

[koiman]

My Modwright SWL 9.0 SE must be an odd ball it is dead quiet on start up and after.