Deluxe Reverb mystery noise??

Chris Gilchrist · Post by **Chris Gilchrist** » 9 Feb 2009 9:00 am

I've got a Deluxe Reverb reissue that's producing a peculiar noise, and wonder if any of the knowledgeable folks here would have ideas as to what's going on.

It seems to produce a relatively quiet but audible "whooshing" noise just after striking a note, sort of like the sound of a blowing wind-- but oddly enough, it only happens when a G note is played, and not with any other note on the scale - it seems to be frequency dependent. I've also noticed that this sound doesn't seem to be amplified much as the volume is turned up. So at regular band volumes, it's not noticeable. But at home, it's just annoying, particularly with lap steel.

It doesn't seem to be a tube or speaker issue. I've swapped out all tubes individually, and tried various speakers. It happens on both channels (normal, vibrato), and doesn't matter whether the reverb or tremolo is on. I've checked the bias and it's running in a 'normal' range (23 mA or so).

Any ideas on what this could be?

Chris Gilchrist · Post by **Chris Gilchrist** » 11 Feb 2009 11:21 am

well, i guess this will just remain a mystery.

Clyde Mattocks · Post by **Clyde Mattocks** » 11 Feb 2009 1:35 pm

Chris, I had hoped someone else would respond to your problem. I have a new Deluxe reissue that I've discussed in another thread. I haven't encountered the problem you're having, but the reverb is a little strange. Like your problem, mine is not so bad when playing out, it's just objectionable at a
home volume.

Paul Arntson · Post by **Paul Arntson** » 12 Feb 2009 9:32 pm

If it only responds at a certain frequency, it might be mechanical. Maybe a cold solder joint or a cracked resistor. The "chopstick test" would help nail it down.

If you already swapped tubes then that eliminates the most likely candidate.

-Paul

Mitch Druckman · Post by **Mitch Druckman** » 13 Feb 2009 7:29 am

I thought it might be related to the ticking sound of the vibrato circuit leaking through while the vibrato is off.

Chris Gilchrist · Post by **Chris Gilchrist** » 13 Feb 2009 7:50 am

thanks for the responses. it does seem like it could be something mechanical, hitting a resonant vibration frequency or something. what's the "chopstick test"?

i went back and studied it a little more, and noted a few more things:
- it doesn't happen until the amp has warmed up (1-2min)
- there's a very slight delay after you strike the string (fractions of a second), and then it lasts about 1 full second after the note is struck, and then ceases, even if the note keeps sustaining
- it's surprisingly consistent - it's been happening for about 6 months, after carrying the amp weekly to practice, etc...., and always is right in the range of F#-G

maybe i'll have to take it to an amp tech, but just wanted to see if anyone had ideas about where this came from. thanks for any other ideas!

Paul Arntson · Post by **Paul Arntson** » 13 Feb 2009 6:48 pm

Hi Chris-
The chopstick test is something a tech needs to do. They run the amp with all the high voltage and dangerous stuff exposed and tap around with an insulated probe very very carefully to find a mechanically sensitive component.
Often it's a dodgy solder joint or a cracked resistor.
Definitely not something to try on the kitchen table.