Fishman Acoustic Matrix Volume control sought

[Jerry Ryan]

I have a Fishman Acoustic Matrix Natural 1 Active pickup to install. It did not come with a volume control. The install data sheet showed that a volume control can be added to the circuit board, I contacted Fishman and they didn't have one or where to refer me.

It would be easiest to install now, not later. Anyone know where to get a volume control for a pizeo pickup??

Thanks!

Jerry

[Ron Frazier]

Any volume control can be installed on any pickup.
A piezo pickup without a battery is not very powerful .

Ron

[Jerry Ryan]

Thanks Ron;

This is an active amplified pickup. Same answer?

[FRANK]

RADIO SHACK ITS THERE

[Jerry Ryan]

Thanks Paul, I'll go to Radio shack!

Jerry

[Mike Kolb]

Try a 1-meg ohm 1/4-watt audio taper pot.... that should be about right. But, if memory serves, doesn't Fishman also have a separate accompanying preamp assembly that can be added to the Acoustic Matrix series?

[Len Biglin]

Hi Jerry , I think what you need to do is seperate the output of the preamp from the jack socket, run a wire from that output to the hot side of the pot ( any pot will do on the output side ) then run a wire from the middle lug of the pot to the jack , and a ground wire to the zero side of the pot and the case of the pot (the body of the jack is always ground). As piezo pickups are very high impedance (Z) you need a pot of at least 1Mohm , 2 is better , if you want to put the pot between the pickup and the preamp , otherwise the sound quality will suffer.So I'd go as above and prefer 25K ohm but it should be ok with a higher one. Len

[Rob Mercure]

I agree with the suggestions concerning adding a potentiometer with the following suggestions: First the piezo is an extermely high impedance device and without a buffering preamp will lose highs, bass, dynamics and generally sound like poop if fed into too low an impedance. So if you can't find a really high impedance pot put another resistor in series with the pot to ground to increase the impedance the P/U "sees." Fer example if you use a 1 M ohm pot then put at least a 3 Meg resistor in series. But this will prevent you from totally killing the P/U output so you might want to get a pot with a switch on the back and wire it across the P/U to be able to kill the P/U is you are on stage. Secondly use an audio taper potentiometer to more closely match the dynamic response curve of the human ear - we are extremely unlinear "pickups" ourselves. Don't use a linear taper pot - if you do you'll find that very little of the "sweep" (part of the circle of rotation of the pot shaft) will be useable and the useable part with come up/down too rapidly.

Rob

[Russell Vance]

Hi Jerry,
Firstly, the Matrix 1 is not a piezio - it's a co-polymer sort of guy and much better than the nasty old piezios.

Fishman had tech sheets for installing a volume and tone control to the tailpin pre-amp which involved soldering some leads onto the additional pads on the pre amp board and removing a micro resistor on the same board. I have done this IAW their tech sheets and the result was unsatisfactory (very little dynamic control) - Fishman acknowledged that this circuit was unsat and that was that. They subsequently came out with an add-on volume and tone control circuit with appropriate buffering etc. Lately they have released the new Matrix with a dedicated volume and tone control attached - this is the way to go if you wish to do what you wish to do. Fiddling around with well intentioned but unsat add-ons will affect the performance of this otherwized excellent transducer system. Thats what I know, I would call Fishman again and talk to their tech area which is (was) very helpful. Rusty.

[Jerry Ryan]

Thanks Rusty,

I'll leave it alone. Your explanation makes sense. I'll contact tech, but the best plan may be to use the tone/volume control on the stage amp!


Jerry

[Rob Mercure]

Hey Rusty,

There are lots of materials that exhibit piezo effect and some are plastics. Rochelle salts was the original, quartz is probably the most famous, but now most are a barium ceramic material. So from what materials I can find on the web this P/U is some sort of piezo P/U which by nature is a very high impedance devices.

But if this P/U has a preamp then the output impedance is buffered down and is probably only around 10K or so. While soldering a pot onto the board pads doesn't work well - as you report - it is always possible to just simple solder a pot across the output of any signal producing device to produce a variable output. And, to repeat myself, all one need allow for is that you can feed a low impedance P/U into a high- impedance input without signal degredation but if feed a high impedance P/U into a low impedance input you'll lose signal strength and highs and probably gain some noise (for maximum voltage transfer an input should be 10 time the source impedance) and also that you use an audio taper pot. Since this has a buffered output I'd try a 10-25 K A pot and see how it sounds,. If there is noticable signal/tonal loss the try pots 10X, etc.,

For a while I made "volume" boxes for friends using various little steel containers that I soldered a 1/4" male to which contained a suitable pot with a 1/4" female output. The idea was to plug them directly into the strapjack output so that the user would have a volume control right there at the guitar and since they were fed from the 1/4" male they could be moved from one guitar/pickup to the next (as long as the pot's impedance was high enough). A simple little construct that I painted black about the size of 1/2 of an Altoids box - easy enough for anyone who solders easily to construct.

Rob

[Russell Vance]

Yep Rob, what you say is sound advice, and if you wish to see the circuits that Fishman use for this rudimentary fix they have them published on their tech section - but, as I said , some are relatively ineffective and Fishman don't recommend some as buffered and matched tone/volume modules are available and now come standard on the new Matrix Infinity system - works sweet.

However, as Rob correctly points out, it's only electricity and all the laws of physics apply - it ultimately just becomes a matter of how much you wish to spend and what ultimate tone quality you wish - sometimes a cheap simple circuit is best (and it costs little to try and gives one valuable experience and confidence is electrical matters) other time we cut to the chase and spend. Thanks Rob.