Spoiler bridge pickup problem

[Cornelius]

Hello everybody,

I think my 89 Spoiler has a problem with either a pick up or the pre-amp. When the trimpots are both fully to the right the neck pickup is much louder than the bridge pickup. I can get them at the same level somewhat by trimming the neck pickup way down and leaving the bridge pickup fully open. The bridge pickup is closer to the strings than the neck pickup by the way. Not only is the neck pickup louder (giving more output) than the bridge pickup, to my ears it also sounds better. Full sound, bridge pick up sounds somewhat thin. Obviously the placing of the two is a big difference but thats not what i'm talking about. The biggest difference is the level of output between the two pickups. Now i am a novice as it comes to owning an Alembic so maybe the bridge pickup is supposed to be giving less output than the neck pickup, i don't know! Or is the bridge pickup broken? Pre-amp maybe?

Kind regards,
Cornelius

[JimmyJ]

Hey Cornelius,

I'm not very familiar with the Spoiler electronics package but if you want to do some experimenting, perhaps you could swap the bridge and neck pickup connectors on the preamp board?  If the bridge pickup is suddenly much louder and fuller and the neck pickup gets quiet and thin sounding, that would point to a problem with the preamp.  Are there 2 opamp chips on that board and are they in sockets?  If yes, you might be able to swap those to test...

Jimmy J

[adriaan]

The single volume with the pickup selector means finding the balance is your main objective, but that's why you have the trimpots. You can compensate for volume differences, so if turning both fully open is not working for you, just turn down the one that is too loud. And if you try different pickup heights (which will give you different sounds) again turn down the one that is too loud, or turn up the one that isn't loud enough.


Have fun!

[Cornelius]

Thanks for your replies! I swapped the connectors around and the output of the bridge pickup is still significantly less then the neck pickup. And the pickup selector switch obviously does standby-bridge-both-neck now. I understand trimming the opamps is for compensating the height of the pickups, not for making up a big difference in volume/output. Could it be that the bridge pickup is broken? Needs a rewound? I could measure the resistance but i don't now what ohmage would be correct/normal.

[pauldo]

Have you tried to move the bridge pickup further away from the strings? 
My limited understanding of electricity and magic is that there is a ‘sweet’ spot where the magnetic field from the pickups receive the strongest signal from.   If you are too close (or too far) to the strings you won’t get as much output.

[JimmyJ]

OK, the next thing to try is a bit trickier, if you're willing...  I believe the two pickups are the same so they are interchangeable.  You could take the strings off, remove only the two pickup mounting screws which you can see the complete head (these two hold the pickups down while the two below hold the pickups up), and physically move the bridge pickup to the neck position. 

You'll want to be careful about the wire running to the neck pickup in particular as it travels through a tunnel in the wood - you MAY need to connect a string to that connector before you pull the pickup so that you have a way to pull the other connector back through.

Run the wires back to the preamp cavity, through the ferrite bead (if your bass has one), and connect to the board.  NOW see what you get.

I will also add that the pickup in the neck position will always have slightly more output because it's closer to the middle of the string.  It hears more of the fundamental note which has more energy than the higher overtones that the bridge pickup hears.  Make sense?  But it shouldn't be as huge a difference as you're describing.

It's rare for pickups to fail because they are solidly potted in the epoxy material.  No moving parts except the lead which comes out the bottom and runs to the board.  Rare, but does occasionally happen.  Your troubleshooting will help figure out if something needs repair or replacement on your bass.

Also, we love pictures in here so if you get the chance to post any, please do.  I don't own a Spoiler so not even sure if the advice I'm spewing is correct. 

Jimmy J

[xlrogue6]

Given 2 identical (more or less) pickups, one in the bridge position will always have less output than the neck pickup, as the arc of string rotation when plucked is less than in the neck position because the string over the bridge pickup is much closer to the witness point (the end of the vibrating part of the string), so it generates less output from an electromagnetic pickup.

[gtrguy]

Use the onboard trimpots to set up your volumes. That is what they are for.

[mica]

Yes - adjust the gains with the trimpots for sure. Generally the neck pickup will be farther away from the strings and the bridge pickup closer to the strings. And the bridge pickup is always thinner and less bassy, hence the moniker "treble pickup" I also favor the neck or "bass" pickup when playing straight blues for instance.

The Spoiler RF upgrade also increases the total gain, so if you find that after adjusting your trimpots to balance the volumes of the pickups the overall output is too low for your liking, you can send the electronics in for an upgrade.

[KR]

Cornelius, raise your bridge pickup up close to the strings. Holding down the last fret, and measuring a clearance of 2mm under the strings at the bridge pickup is a good place to start. Having the bridge pickup much closer to the strings to compensate is normal; one of my Series basses requires this.

[Cornelius]

Thanks for all your tips and advice! When the holidays are over i'll start working them out on my Spoiler and come back with the results.

[Cornelius]

Raising the bridge pickup was the solution, it's much closer to the strings now. I was jumping to conclusions way too quickly while the problem was easily fixable. The pickups are even in output/volume now so i can start balancing my sound with the trimpots. Thanks for you help!

[gtrguy]

Pickup height can make a huge change in tone. Pickups have a 'window' where they best sense the string action. With Alembics I have worked on, they were especially sensitive. Too low and the sound gets more bland. Too close and it gets more live, which can be good or bad. Too high can also interfere with slap tone, as the string can bounce off the pickup. I typically set the pickup height for tone and also check the blend tone to see if I like it. Then I adjust the trimmers to even out the volume.