A Nordstrand NJ4-SV and Audere ??

I have this exact combo in my bass.

The volume drop you're hearing is because of phase cancellation in the signals of the two pickups. This is NOT the same thing as two pickups influencing each other's electrical loading like happens in passive circuits, the Audere has a buffered preamp that doesn't allow that.

The signal provided by the two pickups has a different mix of frequencies taken from the string because they are sensing the string in two different places. This is the difference we hear between a neck pickup and a bridge pickup, even if the two pickups are identical save for their position.

In addition to that, there's a slight time lag between the moment a particular wave on the string passes over one pickup and the next. This means that the waveforms produced by the two pickups are slightly shifted relative to each other in time.

These two effects (especially the second) mean that when you combine the signal of the two pickups, there's a comb filtering effect. Imagine it like a series of spaced out little frequency cuts.... like having a bunch of little EQ knobs spread across the spectrum and turning each of them down a bit.

The effect is the most noticeable to our ears in the midrange, since our ears are most sensitive there. This is why (in my opinion) blending both pickups on a Jazz bass gives such a great slap tone: the mids are scooped a bit in a pleasing way.

Long story short, this is an effect of blending two slightly time shifted signals. Doesn't matter how you blend those signals (run each pickup separately to its own identical amp.. stand equidistant from the two amps and you'll get the same comb filtering.. mixing in air or in electronics doesn't make a difference here) it'll still happen.

Take care, and enjoy those pickups and preamp. I am!

 

Extension for the REALLY curious:

One might hope you could compensate for the comb filtering effect with a precisely timed delay on one pickup's signal. But, the moment the waves in the string traveling from their origin point (your plucking fingers) reflect off the bridge and the fret/nut, those reflections will then approach the pickups from two different directions.

For the waves traveling from the fret/nut, the neck pickup is closer. For the waves traveling from the bridge, the bridge pickup is closer. So any delay you introduce to one of the pickups will by necessity make the situation worse for one set of the waves that make up the string's motion.

It'd be fun to mess around with to see what it did to the tone!

 

I had the same problem with my Audere/NJ4SV combo. Never really figured out what cause it, I sold the JZ3 and bought the vol-vol model and it was an improvement. First off i never used the mid much, and I liked the bass/treble boosts better.

However, you can minimize the phase cancellation by moving your pickups around. You might want to get out a ruler, set the bridge pickup where it should be, and move the neck pickup up and down until you get the tone you want. I was able to add a considerable amount of growl by moving my pickups around. Worth a try.

 

You still have frequency cancellation when combining pickups. It's a given whenever two sources are used. You've just changed which frequencies it's happening at. And each time you move around from fret to fret you've just changed the relationships yet again. So I'm more a proponent of having two good soloed pickup positions. Then I worry about the blend, setting the neck pickup height to give about the same volume as the bridge through my rig with my settings. And if I get some good interesting blends, great! That's pretty much what a J is like.

 

Your welcome, Marty. Keep on playin'!

BTW, my name isn't Jeff. I just have a link in my signature to what I think is one of the most insightful posts on TB, which happens to have been made by TB'er and noted solo bassist Jeff Schmidt.

Yes indeed!

Sounds like a useful technique. I happen to quite like the sound of the dead-center blend on a J (especially with these pickups and preamp DANG!) so I adjust them to maximize my enjoyment of that sound, but I do try to keep either the bridge or neck being too overwhelmingly louder than the other for when I blend way over to one end.