Double Bass Shadow SH 965-NFX Nanoflex Pickup Problems

[Matthijs]

That would be really nice!
I tried once to measure the values and to understand the circuit of the original power supply box, but I completely failed. I´d like to have a one channel only box with the original tone control and an additional adjustable 1.grade high pass filter. I tried to make a high pass filter out of the original volume pot, but that did not work the way I thought it should. No electronic expert policemen around here, are they?

I’ll give it a try, but I’ll need some time to figure it out. What you want is a bit more complicated though. An adjustable hpf is a lot more complicated and I doubt a passive circuit will be very usefull for that. The original tone pot did not get any use by me, so I did not try to figure it out. I always assumed it would be a standard passive tone control as in an electric bass, but with slightly adjusted cap values.

By the way: I owe a lot to the electronics police on Talkbass. They saved me lots of times when I got myself into trouble. (And I’m not only saying that because they might be watching)

the basic circuit I used was something like this ( without the values ):

The battery indicator circuit I used was this one: Invalid Link Removed

Sorry: two transistors, not one, but still pretty simple.

 

[DoubleMIDI]

You could have omitted the two resistors to ground. But that would have more influence on a passive pickup (impedance). Not so much with the NFX, since the JFET is in the pickup.
You might get a bit more battery life without them.

 

[Matthijs]

Thanks Double Midi. I had mu doubts about those. I based this on some examples of mixing preamps for piezo’s online. I believe the thought was this way the filter would be a little more independent from input impedance of the amp?

A question I also considered is wether the the whole thing could be radically simpeler by just combining the two pickup outputs. Like this:

I didn’t do this because the original box doesn’t work that way and I also was planning to maybe make the blend between the two adjustable.

 

[DoubleMIDI]

Not that radically.
The individual outputs need resistors before they get connected. And since the supply voltage needs to go to every pickup you need a resistor from supply voltage to JFET (since you don’t want to short through the JFET). The single capacitor is OK if all inputs get the same supply voltage, if not you need individual ones before the outputs are connected together.

 

[Ric Vice]

I guess that for me, it’s the way most Piezo pickups decay and release each note, that just isn’t authentic to my ears, you can hear a distinct “buzz” as the note decays. They all do that to a greater or lesser extent. The Ehrlund EAP, doesn’t do that, or if it does it’s so negligible that it doesn’t change the timbre of the note. All the other pickups I’ve used from Underwood, Realist, Upton, KNA, Planet Wing, and especially, Fishman BP 100 have that artifact. Listening to the Shadow 965 NFX, Fishman Full Circle, and even the venerable Yamihiko, I still hear it. So, at heart, I’m a microphone lover through and through, with the EAP coming in a close second through the Grace. Just my take of course, I have a Realist Life Line as a backup.

 

[Carfax]

you might want to make a loose knot to shorten the cables. I´d avoid to cross the cables.

Thank you Matthias!
I knew that crossing cables might cause interferences, but never attributed the weird noises I sometimes got on my amp to them. Your comment reminded me of the crossing problem and now I seem to have solved that issue. (I used a twist tie.)

 

[Matthias Hacker]

I had in mind that if you cross the cables, that might cause buzz when the cables are touching each other.
But ok, if you had problem with interferences and now that´s solved, fine!

 

[Ric Vice]

The early Ehrlund EAP's has a similar problem, if the cable lead from the pickup fo the 1/4 inch connector touched the top of the bass, or tailpiece directly you would hear it through the amp.