Alembic Guitars Club

Alembic products => Owning an Alembic => Troubleshooting => Topic started by: mike1762 on June 07, 2010, 06:51:16 AM

Title: Squeal Like a Pig
Post by: mike1762 on June 07, 2010, 06:51:16 AM: My SC will occasional emit a high frequency squeal (not unlike that emitted by Ned Beatty on a camping trip). When it happens, there is no output from the bass other than the squeal. I can get rid of it by plugging/unplugging the cord several times. The cord is fine and the battery is new... it's definitely something in the bass. Any ideas???

(Message edited by mike1762 on June 07, 2010)
Title: Squeal Like a Pig
Post by: sonicus on June 07, 2010, 07:51:08 AM: This might be an internal calibration issue. Perhaps ? Trim pots? I would not go there before talking to Mica or Alembic personnel or others who can give an account of the correct procedure.
Title: Squeal Like a Pig
Post by: lbpesq on June 07, 2010, 08:43:20 AM: Mike:

I have no idea what could be causing this, but I would strongly advise DO NOT TAKE THE BASS ON A CANOE/CAMPING TRIP!

hehehehe

Bill, tgo
Title: Squeal Like a Pig
Post by: pace on June 07, 2010, 10:12:21 AM: Do you notice this when the filters, or Q switch are wide open, or does this occur regardless of your settings?!?
Title: Squeal Like a Pig
Post by: terryc on June 07, 2010, 11:41:38 AM: Corrosion on the input jack can cause this or jack failure.
Without taking the cover plate off right now on my bass I think they are sealed jack sockets so you cann give the terminals a gentle rub with a fine abrasive paper.
Title: Squeal Like a Pig
Post by: mike1762 on June 07, 2010, 08:03:32 PM: I'm not sure about the Q switch/filter thing... the next time it happens I'll see if changing them makes any difference. Since exercising the jack seems to make it go away, that would indicate that the problem is there. But I've never seen jack failure cause anything like this. I'll try the sandpaper thing (on my bass... not on Ned).
Title: Squeal Like a Pig
Post by: terryc on June 08, 2010, 06:49:08 AM: The theory is on the corroded jack terminals is that there is micro arcing which is then amplified by your pre amp and then your amplifier.
Title: Squeal Like a Pig
Post by: mike1762 on June 08, 2010, 12:34:06 PM: OK, that makes sense. I'm out of town at the moment, but I'll clean the jack as soon as I get back home.
Title: Squeal Like a Pig
Post by: mike1762 on August 14, 2010, 11:27:09 AM: All righty then... I have it narrowed down to something to do with the Q switch on the bridge PUP. When the bass starts squealing, it slowly goes away as I pan over to the neck PUP. When I start flipping the Q switch off/on, the character of the squeal will change and then suddenly dissappear (but the squeal, when it's occuring, happens whether the Q switch is on or off). This is happening every time I pick-up the bass. Any ideas?
Title: Squeal Like a Pig
Post by: terryc on August 15, 2010, 10:50:55 AM: Could be the mechanical part of the switch is faulty
Title: Squeal Like a Pig
Post by: mike1762 on August 15, 2010, 01:19:30 PM: Mica??? Could it be something as simple as replacing the switch? Is that something I can do myself?
Title: Squeal Like a Pig
Post by: adriaan on August 15, 2010, 01:26:35 PM: Mike - try a Google search on the Alembic Club for squeal (http://www.google.com/search?source=ig&hl=nl&rlz=1G1ACAW_ENNL339&=&q=squeal+site%3Aalembic.com%2Fclub&aq=f&aqi=&aql=&oq=&gs_rfai= target=_blank) - see what gives.

(Message edited by adriaan on August 15, 2010)
Title: Squeal Like a Pig
Post by: mike1762 on November 30, 2010, 10:42:20 AM: This has continued to be an intermittent problem. I was changing the battery today and was able to reproduce the problem when I accidentally nudged this ceramic(?) tube thingy (let me know if I'm getting too technical) that had some wire looped through it. What is that thing? It appears to have something to do with the problem.
Title: Squeal Like a Pig
Post by: mike1762 on November 30, 2010, 10:55:25 AM: I found this post (http://club.alembic.com/Images/393/8949.html (http://club.alembic.com/index.php?topic=3050)) regarding a similar (same?)problem. I'm guessing the thingy is a ferrite bead. But since I seem to have one, could it still be my problem?
Title: Squeal Like a Pig
Post by: mica on November 30, 2010, 11:32:41 AM: We test electronics for no charge, so you can send them in for a check-up.

The ferrite bead is non-conductive, and it wouldn't contribute to squeals.

You can do the ol' exercise routine and flick the Q-switches bunches (think at least 50 times) and also turn the filter pots completely through their rotation,meaning reach both of the stops at least least 50 times each. This will eliminate corrosion as a culprit.

Otherwise, we're going to have to check it out on the test bench.
Title: Squeal Like a Pig
Post by: mike1762 on November 30, 2010, 01:13:15 PM: If it continues, I'll take you up on that. After repositioning the ferrite bead, the problem (for now anyway) seems to be gone. The bead is just floating around in the control cavity... is it supposed to be attached to anything?
Title: Squeal Like a Pig
Post by: adriaan on November 30, 2010, 01:36:29 PM: Well, the pickup leads need to pass through it - otherwise the bead is of no use.
Title: Squeal Like a Pig
Post by: mike1762 on November 30, 2010, 06:52:10 PM: They're running through it, but the bead is not otherwise attached to anything. I think I understand that the bead is just a non-conductive shield, so I guess it doesn't matter.
Title: Squeal Like a Pig
Post by: adriaan on December 01, 2010, 02:46:21 AM: Correct - it doesn't need to be attached. You can stick a bit of styrofoam to it to keep it from rattling against the back plate.