It is currently Mon Mar 16, 2020 9:18 am

All times are UTC - 7 hours



Post new topic Reply to topic  [ 5 posts ] 
Author Message
Post subject: Trim pots on Fender GB41SCE Acoustic/Electric Bass?
Posted: Wed Nov 14, 2012 12:21 pm
Offline
Hobbyist
Hobbyist

Joined: Wed Nov 14, 2012 12:13 pm
Posts: 2
Hi everyone:

First post... Hope you can all help.

Are there trim pots for individual string volume on this instrument? I just bought a used one, and the A string is significantly softer than the other 3 strings.
:?:
Any help you can give me would be greatly appreciated. Thanks.


Top
Profile
Fender Play Winter Sale 2020
Post subject: Re: Trim pots on Fender GB41SCE Acoustic/Electric Bass?
Posted: Wed Nov 14, 2012 3:37 pm
Offline
Rock Star
Rock Star
User avatar

Joined: Thu Aug 07, 2008 3:12 pm
Posts: 6355
Location: Albemarle, NC
Hi MMMM, Welcome to the Fender Bass Forum!

Have you tried a new set of strings? My best hope for you is that it is a dead string or a mismatched one. That is about all anyone but a skilled acoustic/electric tech should try to remedy this issue on that instrument.

There are no individual trim pots, as nice as that might be. The signal from the string is not picked up by individual poles as on a conventional pickup but rather collectively through a one piece under-saddle sensor. The Fishman Classic preamp systems used the Fishman Sonicore coaxial pickups which are a thin skinny and slightly curved metal sensor strip about the width of a bobby pin that rests in the same channel where the bridge saddle rests with the bridge saddle pressing down on it to make contact so it can pickup the vibrations generated by the strings which are transferred to the pickup strip through the saddle. To do this properly the pickup requires uniform contact with the bridge saddle all across the string spacing. These Sonicore pickups and the saddle channel have a slight curve in them and replacing the original Sonicore pickup with about anything else actually requires modifying the saddle channel bottom on the instrument itself and I would not go there at all so long as the pickup is working and yours obviously is working.

This type pickup generally has a very uniform output across a wide spectrum but alignment and uniform contact with the bridge saddle all across the string spread is critical. This alignment would have probably been fine from the factory and if left alone should never need much adjustment. If string to string balance is now an issue with all other strings louder than the A string I would first suspect (and hope) the A string is dead, dying, damaged or mismatched and that new strings remedy the output mismatch. That is the simplest fix.

If new strings offer no improvement, the next most likely cause is because the saddle is not making good contact with the pickup strip under the A string. This lack of good contact should be addressed by skillful reshaping of the saddle where it contacts the pickup strip by someone with the experience and tools to do that correctly. I wouldn't dare touch something that delicate myself and discourage you from fooling with it at all. In the first place I'm not skilled enough and in the second place I don't have the proper tools to do that.

There is good news! These pickups and preamps usually either work or don't all across the instrument's range and in most cases never require any maintenance or adjustment at all, so long as the bridge saddle is not changed or monkeyed with. Your electronics are working!

If someone changed the saddle and didn't properly shape it to make good contact with the pickup all across the string spread or used the wrong saddle shape entirely then that explains the weak A string output. It could have come that way, but I don't see it getting past quality control people like that because they check string to string balance.

A third less likely yet still possible explanation is some sort of pickup alignment issue which you'd have to remove the saddle to investigate such as would result from a collapse or compression of the wood under the pickup around the A string location. With the E & D strings sounding fine on either side of the A string I'm doubting a pickup alignment issue is the cause. The cause is far more likely to be either a bad string or bad saddle to pickup contact around the A string.

Since these pickups are under the saddle, string height and setup of the neck has no effect on the tone or string to string balance as is the case with a conventional electric bass pickup. These sensors pickup vibrations that come to it from direct contact with the saddle. If the saddle isn't making good contact with the sensor around the A string then of course the volume of the A string would fall off.

So to review I suspect possible causes in order to check are:
1. Bad A string. Restring yourself. The next two possibilities are for a tech to check.
2. Saddle needs some reshaping to improve uniform contact of the saddle with the pickup.
3. Longshot is a pickup alignment/placement issue which could result from some sort of compression or collapse of the groove where the pickup lies under the saddle so that contact is uneven no matter how you shape the bridge saddle.

Fooling with the pickup strip under the saddle or the saddle shaping to improve pickup contact are things to leave to an experienced acoustic/electric tech or you might regret it as replacement parts for the obsolete Fishman Classic systems are a tough find and you usually have to substitute something newer or even install all new electronics and saddle if you damage one of these now obsolete slightly curved coaxial pickups. Your pickup and electronics are not the issue, so let's not create a new issue by messing with them or suspecting them as the cause. They are not the cause.

I say that because the pickup is working well on all 3 of the other strings. I think it is something fit related and you are not looking at buying any new parts, beyond strings or perhaps a new bridge saddle at the most. If a new set of strings doesn't fix it then have a tech check the saddle contact with the pickup. This should be a quick and relatively easy fix for a good tech. At the worst you might need a new saddle, just a few bucks.

The absolute worst case scenario I anticipate is that the tech will have to do some bridge saddle channel reshaping to improve pickup alignment. This could involve building the channel back up and then reshaping it evenly across the string spread then do some minor reshaping of the saddle for a perfect fit in the newly reshaped channel. The other solutions are easier and quicker but this one is the most involved solution I would personally anticipate. It is also unlikely that it will be that complicated.


Top
Profile
Post subject: Re: Trim pots on Fender GB41SCE Acoustic/Electric Bass?
Posted: Thu Nov 15, 2012 7:38 am
Offline
Hobbyist
Hobbyist

Joined: Wed Nov 14, 2012 12:13 pm
Posts: 2
Thanks, Dave... This actually explains a lot.

When I bought this guitar last week (in a pawn shop - had an acoustic gig coming up, went by the place, saw it in the window and bought it), the strings were literally GREEN. So of course, first order of business was to change the strings.

While i was doing this, the bridge saddle came out of the bridge. I put it back in the "guesstimated" way it came out. Perhaps that's the problem. I'll take the strings off and see it the saddle is situated the proper way. If not, time for the luthier i suspect.

Thanks again, Dave. this is my first experience with ABGs. Perhaps you can answer another question... I find these things to be RIDICULOUSLY bright :? , and was wondering if tapewound strings can dampen some of that enthusiastic high end. Any thoughts would be welcome/ appreciated.


Top
Profile
Post subject: Re: Trim pots on Fender GB41SCE Acoustic/Electric Bass?
Posted: Sat Nov 17, 2012 1:25 am
Offline
Rock Star
Rock Star
User avatar

Joined: Thu Aug 07, 2008 3:12 pm
Posts: 6355
Location: Albemarle, NC
I am no expert on Acoustic Electric Bass strings. I do know enough to watch the tension as acoustic bass strings have fairly low tension compared to most electric bass strings. If you can find nylons to match that tension they would be safe to try. I'd stick to strings designed for an acoustic otherwise and set the EQ to tame as much brightness as possible and make up the rest on amp EQ. The nylons I've tried were more medium tension. Ridiculously bright is good for some things. lol.


Top
Profile
Post subject: Re: Trim pots on Fender GB41SCE Acoustic/Electric Bass?
Posted: Sat Nov 17, 2012 1:37 am
Offline
Rock Star
Rock Star
User avatar

Joined: Thu Aug 07, 2008 3:12 pm
Posts: 6355
Location: Albemarle, NC
I just realized that the brightness complaint might also be addressed by an ill-fitting bridge saddle. I think that is also where your tonal complaint lies. You are not getting a good transfer of vibration to the pickup.


Top
Profile
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 5 posts ] 

All times are UTC - 7 hours

Fender Play Winter Sale 2020

Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to: