Vigier Guitars

Hello.
I have a Vigier Excess Bass (4 strings) that distorts when playing the fourth string (E). The sound of the rest of the strings seems to be fine unless you play the string strong, then the distortion also happens.
When the distortion occurs it also decreases the volume of that string, so there is a difference in the volume when playing the other strings.
I have tried using a compressor / limiter and several bass amplifiers but the distortion problem remains in all conditions.
I changed the original battery for a new one and it does not distort as much as before, but the distortion still persists.
Do you know what can be causing this problem and how to solve it?
I think it can be a pickups issue, I was thinking about changing the original pickups and use EMG. Do you know what is the active pickup EMG model/s that can be used in the Vigier Excess?
Thank you.

Can somebody help me, please?

The pickups
are not the reason of your problem.

It sounds
like your battery is dead, but you changed it. Do you use a cable with a brass
jack? Because brass gets oxidized and the connection becomes bad which affect
the power supply.

No, I have tried with 4 new jack cables and the result is the same for each one.
Can be an issue of the jack input connector in the bass? Maybe that input is not transmitting the signal correctly.
What other things can I check?

Are you sure it is the bass and not the amps input? If you lower the volume of the bass, do you have the same problem?

I have tried it with two bass amps and the result is the same.
I have also tried different volumes for the bass and amp but the problem persists.
I have realized that it happens when I play the string harder, if I play it soft it does not distort, but with my other two basses it does not happen no matter how hard I play the string.

Well... I should see your electronic.

Is then a pickups issue? preamp? ... What do you think is the problem?

I have to see the bass to be sure.

Finally it is solved. It seems that the problem was a little screw acting as a booster and the height of the pickups. That booster is inside a small hole between the bass knobs. I have not found any documentation about it in the user's manual. Could you please tell me some information about it?

This is not a booster, it is a noise reducer. It is all explained in the manual. Here for example

I thought it was gone, but not, the problem of distorsion still remained. It has been definitely gone by adjusting the height of the neck pickup. Lowering it has stopped the distortion problem.

I have recently purchased a second hand Vigier Excess Original also with Benedetti pickups. This bass does not have the distortion problem in the E string. It has a lot of treble and high end even when the treble knob is little raised, so I have to raise the bass knob a lot to compensate it.Another thing I have found is that it has less output than the Vigier Excess with the distortion problem. I have to raise the volume knob in my amp to get the same volume.The pickups of this new bass are close to the strings, and I find this more comfortable to play.What could be the explanation of different output levels between these two Vigier Excess basses? The one with the distortion problem has the pickups lowered to minimize that distortion, those pickups are noisier and does not has as much treble as the new one.Is it normal that the new bass has lots of treble and high end?How can I raise the pickups close to the strings and avoid the distortion problem in the old bass? I have to lower them in order to minimize the distortion problem. Both basses have pickguard, so I figure that they were built in 1996.