| Author | Message | ||
| mike1762
Senior Member Username: mike1762 Post Number: 564 Registered: 1-2008 |
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) | ||
| sonicus
Senior Member Username: sonicus Post Number: 1036 Registered: 5-2009 |
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. | ||
| lbpesq
Senior Member Username: lbpesq Post Number: 4457 Registered: 7-2004 |
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 | ||
| pace
Senior Member Username: pace Post Number: 556 Registered: 4-2004 |
Do you notice this when the filters, or Q switch are wide open, or does this occur regardless of your settings?!? | ||
| terryc
Senior Member Username: terryc Post Number: 1241 Registered: 11-2004 |
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. | ||
| mike1762
Senior Member Username: mike1762 Post Number: 565 Registered: 1-2008 |
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). | ||
| terryc
Senior Member Username: terryc Post Number: 1249 Registered: 11-2004 |
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. | ||
| mike1762
Senior Member Username: mike1762 Post Number: 566 Registered: 1-2008 |
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. | ||
| mike1762
Senior Member Username: mike1762 Post Number: 629 Registered: 1-2008 |
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? | ||
| terryc
Senior Member Username: terryc Post Number: 1313 Registered: 11-2004 |
Could be the mechanical part of the switch is faulty | ||
| mike1762
Senior Member Username: mike1762 Post Number: 630 Registered: 1-2008 |
Mica??? Could it be something as simple as replacing the switch? Is that something I can do myself? | ||
| adriaan
Moderator Username: adriaan Post Number: 2560 Registered: 6-2002 |
Mike - try a Google search on the Alembic Club for "squeal" - see what gives. (Message edited by adriaan on August 15, 2010) | ||
| mike1762
Senior Member Username: mike1762 Post Number: 685 Registered: 1-2008 |
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. | ||
| mike1762
Senior Member Username: mike1762 Post Number: 686 Registered: 1-2008 |
I found this post (http://alembic.com/club/messages/393/8949.html) 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? | ||
| mica
Moderator Username: mica Post Number: 7077 Registered: 6-2000 |
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. | ||
| mike1762
Senior Member Username: mike1762 Post Number: 687 Registered: 1-2008 |
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? | ||
| adriaan
Moderator Username: adriaan Post Number: 2702 Registered: 6-2002 |
Well, the pickup leads need to pass through it - otherwise the bead is of no use. | ||
| mike1762
Senior Member Username: mike1762 Post Number: 688 Registered: 1-2008 |
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. | ||
| adriaan
Moderator Username: adriaan Post Number: 2703 Registered: 6-2002 |
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. |
