Distorsion From Active Bass

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Jns223

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Hi
I have an issue with distorted signal in active mode. It is a thumb nt4 -90 with bartolini soapbar and j-mic, mec two-way electronics and preamp. Could this possible be generated by to high position of the microphones, they have been adjusted lately or could it be the preamp? Any known issues? Optimal mic hight on bartolinis? And yes i have checked the battery. Any suggestions on this matter?
 
Jns223 said:
Hi
I have an issue with distorted signal in active mode. It is a thumb nt4 -90 with bartolini soapbar and j-mic, mec two-way electronics and preamp. Could this possible be generated by to high position of the microphones, they have been adjusted lately or could it be the preamp? Any known issues? Optimal mic hight on bartolinis? And yes i have checked the battery. Any suggestions on this matter?
Click to expand...
By microphones do you mean Pick Up's? If so lower them and see what happens.
 
Is the noise there all the time? Or just when you play notes, they sound distorted?
Not that I can tell much with your answer though. It may well be a semi-fried preamp.
 
When i play it sounds distorted, no hum or anything when not played.
 
Jns223 said:
When i play it sounds distorted, no hum or anything when not played.
Click to expand...

The preamp could still be damaged. Did you mention you changed the pickup heights lately? If you
raised them, you can try lowering them. Also what is the "j-mic"? Am I missing something here?
 
The old two band pre-amp has a white trim pot on top of it.
This regulates the input signal for the pre-amp coming from the pickups

If you raised the pickups they probably now have a higher output, which can cause distortion in the pre-amp.
Lowering the signal going into the pre-amp by turning the trim pot counter clockwise will most probably solve your problem.
Best practice is setting the trim pot so that in active and passive modes your output level is about the same, the trim pot only changes your active volume.
 
Yay! Super reply! I Will try that. The bass has always had pretty huge difference in volymen between active and passive mode so this info. may sort that problem to!
 
I was sure Dr. DiMarco had the cure.
 
I had that same problem once, it was on a brand new Glockenklang preamp. It was born dead.
'hope it's not your case.
 
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