PDF85 wiring questions

[Keyboardmechanic]

Hey Howdy!

Hoping for some help or direction with my PDF85. If somebody can answer here I appreciate it, otherwise if there is another resource I can reference please let me know.

I’m wiring in a set of Fishman Fluence Moderns because the USMs are just too dark to give me the tone range I like to play in. (Plus I was getting some buzzing so the wiring needs to be corrected anyway)

I noticed the mag tone and volume pots run into the pcb, curious about what the board does with this signal because they are still typical pot values.

-If I wire the 25k pots for the fluence into the board would there be any issue? Would I retain my blend with the piezo? And finally would I be able to use the existing 9v power to run my active voicing in this same circuit?

-Alternative is to wire the fluence on their own circuit and throw another 9v in the cavity, just using a switch to go on/off piezo.

My wiring understanding is still rudimentary. [/pickups]

[mmmguitar]

Welcome, @Keyboardmechanic. The short answer is that there won't be any issue with running the Fluence signal outputted from the 25k volume pot into the piezo preamp, and you can run them off a single 9v battery (or li-ion battery pack). The only consequence will be the current draw of two preamps draining the battery faster.

That said, the iteration of preamp in the guitar is going to affect how you achieve this:

Does your guitar use the Fishman Powerchip (chrome saddles)

powerchip.jpeg (41.52 KiB) Viewed 856 times

Or the Graph Tech Acousti-Phonic (black saddles)?

This thread might have extra info you can use.

[Keyboardmechanic]

This is the most helpful reply I’ve seen to a forum post in a long time.

I have the black saddles and the graphtech chip.

[mmmguitar]

I have the black saddles and the graphtech chip.

This diagram from the other thread shows how you can power the Graph Tech and Fluence preamps from a single battery. The short of it is that the Acousti-Phonic preamp has an "aux power" pin that should already be connected to a shortened, free red wire on the 4-pin plug connected to the guitar's existing battery.

I'm happy to help you figure out or troubleshoot the rest of the job - Just be sure to include some photos of the hardware we're working with (including the output jack). And thanks for the compliment - With any luck, I won't manage to totally mislead you.

[Keyboardmechanic]

You are an absolute saint.

[mmmguitar]

You are an absolute saint.

It's easy when you're the one doing all the labor .

Edit: I subsequently saw your post in the FB group; and it looks like your guitar uses Graph Tech's proprietary switching jack.

jack.jpeg (29.95 KiB) Viewed 818 times

It also likely has this part for the battery power:

bat wire.jpeg (17.75 KiB) Viewed 818 times

Here's a battery wire plug assembly Graph Tech sells specifically for incorporating active pickups, in case you don't want to source a single 100uf cap separately, or have to splice wire into you're guitar's existing battery positive aux wire to extend it.

And in the event you wire this all up and decide the Graph Tech preamp is adding excessive noise to your Fluence signal, there's a diagram for a preamp bypass switch in this thread.

[Keyboardmechanic]

Cool.

Yeah I’m going to take a look at what I have tonight. The Fluence kit came with a few caps and an active output jack.

Now that I have a diagram I am going to look at the layout and clip the leads to desolder etc and take inventory. I also need to do a little better wire management because it’s a freaking mess.

Lastly I saw some Parkers had a stereo out so I was going to do a little research on that and see if I’d like to setup as such. I’m already wanting to record out as stereo from my pod go into my scarlett just so I can add a little more depth and shape on tracks, but the idea of stereo output has intrigued me for a while.

[mmmguitar]

The Fluence kit came with a few caps and an active output jack.

Though I'm unsure of which kit you purchased, the included caps should be for the 25k tone pot(s), and the jack will be redundant to the one already in your PDF because the "active" output jack is distinguished by a contact lug which connects a battery-negative wire to ground when a 1/4" plug is inserted into the jack. The Graph Tech jack in your PDF has an extra lug for a separate wire which the preamp uses for its stereo-switching (a T/R/S plug breaks the connection). So to retain the stereo-switching of your Graph Tech preamp, stick with the jack currently in the guitar. You actually won't even need to deal with the jack at all when incorporating the Fluences (unless a connection comes loose and forces you to resolder it).

Now that I have a diagram I am going to look at the layout and clip the leads to desolder etc and take inventory. I also need to do a little better wire management because it’s a freaking mess.

Yeah; for some reason Graph Tech sells you a foot more wire than you need with all of their modular components.

[Keyboardmechanic]

224k250 is the cap. Looks like .22uf.

[Keyboardmechanic]

Alright! Got it wired. Still not pretty in there, especially since the wiring from the fluence is so thick. But that’s a problem for another time.

Right now I am trying to figure out why I have a bit of a whine/hum when going through an amp or using the wireless on my pod go. If I plug directly into the pod there is no noise.

My next step is to go through and just see if adding a ground helps, but is it possible the 9v is backfeeding through the system somehow?

[mmmguitar]

Right now I am trying to figure out why I have a bit of a whine/hum when going through an amp or using the wireless on my pod go. If I plug directly into the pod there is no noise[...]is it possible the 9v is backfeeding through the system somehow?

Just to be clear: Your signal path is

Fluence pickups and 25k pots > Acousti-Phonic preamp > Graph Tech stereo switching jack with the stock red, blue, black, and white wires connected to preamp via multi-pin plug, with the Fluence and Graph Tech preamps powered by one 9v alkaline battery?

What do you have the extra ground wire for the stereo jack wiring harness connected to? Are your 1/4” plugs for the cable and wireless both T/S? How long is the cable? You may also want to email Fishman and GraphTech to see if they have your particular symptom on file - If it ends up being due to an impedance mismatch, they may have a prescribed cap or resistor value to swap in.

If the Pod Go is the only gear which removes the noise (when going wired), does it have an input noise gate or ground lift engaged, so far as you know?