Alembic Guitars Club

Alembic products => Owning an Alembic => Troubleshooting => Topic started by: rv_bass on January 05, 2019, 11:44:38 AM

Title: F-1X and Noise Gate
Post by: rv_bass on January 05, 2019, 11:44:38 AM

I keep the treble at around 6 or 7 and the Deep switch engaged on my F-1X, which creates a bit of white noise when I boost the volume from the F-1X.  Is there a way to put a nose gate of sorts in the chain to reduce or eliminate the white noise?

Title: Re: F-1X and Noise Gate
Post by: gtrguy on January 05, 2019, 11:55:30 AM

You can always gate the noise. I am thinking the unit should not be putting out that much noise though. I would exercise the pots, clean the 1/4" inputs and outputs with a 9mm pistol cleaning brass brush, clean any internal switching jack 'points' with fine wet/dry 600 grit (or finer) sandpaper (use it dry), and try switching the tube, to see if it gets better.

Title: Re: F-1X and Noise Gate
Post by: rv_bass on January 05, 2019, 12:17:49 PM

Thanks for the reply, gtrguy.  I've done the pot and jack exercising, but I'll try the more extensive cleaning with sandpaper, etc. that you suggest and see how that goes. 

Title: Re: F-1X and Noise Gate
Post by: StephenR on January 05, 2019, 01:46:18 PM

Noisy preamp tube?

Title: Re: F-1X and Noise Gate
Post by: rv_bass on January 05, 2019, 02:00:25 PM

The tube is pretty new, but I’ll check it.  I’ll swap it out with another and see how it sounds.

Title: Re: F-1X and Noise Gate
Post by: JimmyJ on January 05, 2019, 03:35:44 PM

Could it be a gain structure thing?  Can you send more level into the F-1X inputs so you don't need to have the volume up so high?  Just a thought.

Jimmy J

Title: Re: F-1X and Noise Gate
Post by: rv_bass on January 05, 2019, 08:06:54 PM

Thanks, Jimmy and others for your suggestions. I'll check the output tomorrow and see if I can increase it with the gain trim pot.  I'll swap out tubes tomorrow as well as suggested by Stephen and gtrguy.  I did try the bass with my F-2B for comparison and don't seem to have the same noise issue with the F-2B.  I'll keep working on it.

Title: Re: F-1X and Noise Gate
Post by: gtrguy on January 06, 2019, 11:20:29 AM

New JJ tubes are always great. Sometimes a few tube brands will not fit into the metal shielding around the socket.

Title: Re: F-1X and Noise Gate
Post by: rv_bass on January 06, 2019, 12:31:41 PM

Thanks, gtrguy.   I worked through exercising the pots and jacks again today. 

I also exchanged tubes between the F-1X with the initial noise issue (affected F-1X) and a spare F-1X that I found in a closet that I had forgotten about (oops!). At first there was no reduction in noise level in the affected F-1X with either tube used, and the backup F-1X had no noise using either tube. Then when I put the original tube back in the affected F-1X, the noise was greatly reduced.  Maybe the act of swapping in and out the tube created better contact points for the tube in the affected F-1X.  Regardless, looks like the issue is resolved.
The affected F-1X had a Mesa - Russian 2, 12AX7-A tube that looked pretty new.  The backup F-1X had a Ruby 12AX7A tube that looked older. 

Results: things are back up and working.  Thanks for all the help everyone!  :)

Title: Re: F-1X and Noise Gate
Post by: elwoodblue on January 06, 2019, 04:09:25 PM

Great news,


 You'd be surprised how many amps that come through my friend's amp shop that
are just in need of pin retensioning and/or conact cleaning.


I should dig into my gear closet...wonder what I've forgotten bout  ;)

Title: Re: F-1X and Noise Gate
Post by: StephenR on January 06, 2019, 06:57:55 PM

Sounds like we need to add "exercising the preamp tube socket contacts" to the troubleshooting techniques. Good to hear it was a simple fix and you rediscovered your spare F-1X in the process.