Replicate Fly piezo electronics

[JimmyFly]

I'd like to replicate my Fly Classic's electronics for a guitar I'm building. Fishman has a Powerbridge with piezo saddles that can be paired with their fishman powerchip volume control to blend the piezo and magnetic pickups. However there is no tone control for the piezo, unlike my fly classic which has a dual volume/tone knob. Any suggestions for adding a volume/tone control for a fishman piezo pickup or using a different piezo solution?

[mmmguitar]

Any suggestions for adding a volume/tone control for a fishman piezo pickup or using a different piezo solution?

I believe I can help with both, depending on your needs:

If you’re specifically wanting a stacked piezo vol/tone pot, I’d suggest going Graphtech or RMC, rather than Fishman. This is because the modern Powerchip preamp is hard-soldered to a "B20K"-spec'd PCB mount audio taper pot for “ease of installation” (though essentially limiting you to a piezo volume pot with trim pots on the underside of it). You can desolder the PCB mount pot from the Fishman preamp - But it’s only necessary if you’re dead set on sticking with Fishman. As I recall, a few years back there was a Parker owner with a previous iteration Powerchip (preamp with larger circuit board footprint and separate volume pot) who was told by Fishman that the all-in-one version is the only one currently produced or available as a replacement part.

Alternatively, Graphtech’s Acoustiphonic kit has a modular plug system in which it’s much more straightforward to desolder the wires running to the included generic 250k mini volume pot, then transfer them over to a stacked 250k vol/tone pot.

This is assuming you’re wanting to replicate a facsimile of your Ken-era Classic’s control scheme exactly (i.e., two humbuckers, master volume, mag volume, mag selector switch, mag tone, mag/mix/piezo selector switch, stacked piezo vol/tone). If you’re entertaining other options/switching, just let me know - If you’re open to the idea of separate piezo volume and tone pots, you need only solder a pot in parallel with the preamp input.

[JimmyFly]

3M, thanks for your suggestions! Lots to chew on here. I've seen some disappointing reviews about the powerchip and you provide some nice alternatives.

[Patzag]

I will add that the Graphtech preamp is "noisy". Meaning that if you go through the preamp for your guitar tones, it's unusable for higher gain sounds. it sounds wonderful on clean and piezo tones though.

[mmmguitar]

I will add that the Graphtech preamp is "noisy".

I often forget that people have this issue; due to my only using their Hexpander board [Update: I subsequently tried the GraphTech preamp...and found it noisy ]. @JimmyFly, Pat has previously shared a diagram in which a 4PDT toggle switch allows you to retain mag/mix/piezo switching in a capacity where the magnetic-only position bypasses the preamp (for less signal noise and the option to still use the magnetic pickups in the event of a dead battery) in both Fishman and Graphtech use. More food for thought.

[JimmyFly]

3M and Pat, thanks so much! Ideally I'd like the same set up as a the Fly. I will apologize up front as I am way out of my wheelhouse so if I ask dumb or redundant questions, pls forgive. For background I mostly play jazz standards through a solidstate henriksen jazz amp so I love the neck pickup and sometimes mix the piezo in. On occasion I use the bridge PU for the few rock tunes I know. I'm pretty sure I want the Fishman powerbridge from on-line reviews and i agree about using something other than their powerchip. I'd like to use concentric stacked pots for everything but I'm not sure how to choose the correct pot and cap combo as well as adding the mono/stereo switch. My question is, any other observations/recommendations and what would the parts list look like? Any suggestions on humbuckers for this setup? I love the Dimarzio sound on the fly but they are smaller than what's on the market today. B/R, Jim

[mmmguitar]

@JimmyFly, modern piezo preamps will switch between mono and stereo automatically, depending on whether you plug in a T/S or T/R/S cable - So the early '90s red mono/stereo button won't carry over to the new guitar (though, if you insist, adding one would be a matter to discuss with the preamp manufacturer).

Cap values are a matter of preference - Though typically .022µF or .047µF cap values for the piezo tone (assuming a concentric 250k piezo vol/tone in conjunction with an onboard preamp, potentially in conjunction with a resistor for whatever impedance the piezo needs to "see") should be a fair place to start.

The mag vol/tone pot value used for Flys was 250k, in an effort to tame the highs some people found excessive in Fly guitars. Whichever piezo preamp you end up going with will likely specify a volume pot value in the area of either 250k (Graph Tech) or 10-20k (Fishman). I don't know what kind of guitar you're building, but I'll be surprised if it ends up sounding like your Fly - You may find yourself going with a 500k or even 1M mag volume pot in the end to bridge the difference between the two guitars.

If you're set on going with a Fishman PowerBridge and use a different brand of preamp, you're likely going to have to solder the individual element leads directly to the connector pins on the other preamp. No matter which brand of preamp you go with, using concentric vol/tone pots with it will require some extra soldering - So something to consider is that you might just as well stick with the Fishman PowerChip and then replace the pot soldered to the preamp with a dual concentric pot (though the single gang pot on the Powerchip in my parts box is spec'd "B20K", Fishman officially recommends a B100-250k pot for a tone control); being as you'll likely have to desolder/solder the stacked pot in, regardless of preamp used.

Feel free to just let us know which parts you're settling on one component at a time; and we can help piece together the final details as the whole circuit becomes clearer. I don't mind making up some crude MS Paint-quality diagrams to help - but it won't be until most (if not all) of the components have been settled on. Were you set on including the pre-refined Fly master volume, as well? Because incorporating one is tricky in the sense that any resistor between the buffered piezo preamp-out and the output jack will interfere with the preamp's ability to auto-detect mono/stereo plugs.

As far as pickups go, it again comes down to your preferences. In my meager opinion, I don't feel the Dimarzio Tone Zone and Air Norton sound the same as their Fly counterparts (nor would I expect them to). Is your build going to have 24 frets?

My day job has had me away from my guitars and related projects for going on three weeks, now (I generally make these posts on the clock during downtime). So again I claim that one of these years, I will finally get around to posting some pickup demos which I hope would help inform such projects. I find the Bluesbucker and PAF Master neck to be two neck position humbuckers from Dimarzio that help my bad Joe Pass impression sound a little better (I currently have them in two of my Flys).

[JimmyFly]

3m, Sorry it's taken this long to thank you for your detailed response. This is great info and still reviewing the details.

[mmmguitar]

3m, Sorry it's taken this long to thank you for your detailed response. This is great info and still reviewing the details.

No worries, at all. I'm quite informal in such matters, and you can trust that any question which results in a wall of text from me has helped me stave off tedium elsewhere.

[mmmguitar]

I'm placing this here until I find a more appropriate thread:

After fabricating one for a repair, a store named Flippin' Guitars has modified some Switchcraft barrel jacks to make a batch of replacement 90's Fly jacks; and are selling them on Reverb.

Being as I don't use any of the original electronics hardware in my Flys, I'm curious to see what the Fly Clone community thinks of these.

[enoughtobedangerous]

Just ordered one and thanks for the info! Just got my first Fly and the output jack is so loose I can't play it. Thought I'd just bend the barbs in a bit until I opened up the back.

[Patzag]

Just ordered one and thanks for the info! Just got my first Fly and the output jack is so loose I can't play it. Thought I'd just bend the barbs in a bit until I opened up the back.

Now the "loose plug" syndrome is often due to the jack not sticking out enough. You have to open the back plate and adjust the sleeve on the jack so that the plug goes in all the way. If the retaining bolt is too far outward, the sleeve won't go in all the way and the plug won't click fully.

Check it out. Much easier than replacing the entire jack.

[JimmyFly]

In Dec '22 my intent was to build a guitar replicating my '96Fly Classic. That changed with the recent purchase of a Strandberg Boden Standard 6. I love the guitar design, neck, etc but underwhelmed by the electronics so I've gutted it to add the original Fly Dimarzio pickups, Fishman Powerchip and rechargable 9v battery pack. The tiny piezo elements came from a deconstructed DoPro Tune-o-matic bridge. (I bought a Fishman power bridge but it was too expensive to destroy for the piezo elements) I drilled a shallow 4.5mm hole under each of the Strandberg's individual mounting plates directly below each saddle to pick up the most vibration and ran the 30awg wires into the bridge pickup cavity.

To have the same piezo vol/tone knob config as the Fly I removed the volume pot from the Power-Bridge intending to replace it with a concentric vol/tone pot. Here's where it gets interesting, I bought a 250k concentric pot based on the forum's feedback but the Powerchip's vol pot (I discovered last night) was only 10k! Ouch! Unbelievably I found a concentric A10k / A10k concentric pot in Berlin Germany. It was fairly cheap so I bought it. Any thoughts on this? Do I go with the 10k or 250k pots? I suppose I could try both but that's a lot of tiny soldering.

I'm on the fence abt adding a master volume since i already have to drill 2 new holes for the piezo pot and toggle switch. BTW, I'm using all mini components to fit in a very small cavity. Still waiting for some components to arrive to complete the build. Will post my findings as I'm sure you are as curious as I am as to what this will sound like.

[mmmguitar]

I bought a 250k concentric pot based on the forum's feedback but the Powerchip's vol pot (I discovered last night) was only 10k! Ouch!

I dug a Fishman Powerchip board out of my parts box, and found the volume pot to be linear taper ("B"), 20k-rated. Your A10k pot should still work for the project.

I think there may be a bit of a "telephone game" situation going on with the listed pot specs (I just referenced the Powerchip manual and some factory diagrams; and see 250k pot values for the mag circuit listed - But no value listed for the Powerchip). I think one of us may have initially referenced a sheet or diagram somewhere spec-ing 250k pots (such as in the Graph Tech preamp sheet), then conflated the two. For what it's worth, I'll go through and edit any posts to do with the Powerchip pot spec to reflect this updated info. I am indeed looking forward to your findings!

[JimmyFly]

As mentioned earlier, I was able to purchase an audio 10k concentric pot to replace the 10k volume pot attached to the Fishman power chip board.

My question is, what size cap do I use on the tone pot for the piezo?

[mmmguitar]

My question is, what size cap do I use on the tone pot for the piezo?

My apologies for the delay in replying to this - I emailed Fishman; and am waiting to hear back concerning their prescribed component values.

Because I have no firsthand experience with adding a tone control to a Powerchip (in which the 20k pot value appears to be due to the volume control being placed closer to the input stage of the preamp; due to any changes to impedance in the output stage interfering with the mono/stereo-sensing aspect of the design), I've been researching other firsthand accounts of people adding tone controls to piezo preamps lacking one.

The below is a placeholder post from an old Google Groups discussion; and I'll be adding and/or replacing with Fishman's answer [Update: Fishman's response was included in my subsequent post]. The short of it is that some experimentation with resistor values in the connection between the input lug of the volume pot and input lug of the tone pot to establish the Hz range of the cap's treble rolloff will be necessary:

Tone caps work against whatever impedance is 'upstream.' [...]
The problem can be solved by simply inserting a resistor in between
the output pin and your added controls. Call it R.

You want R to be higher in value than your approximated output
impedance, but maybe 1/4 value of your volume and tone pots. I think
your output impedance may be around 5k, so try a 10k series resistor R
for a start. Yeah that's not 1/4 the value of your tone pot, but if
you don't have another 50k, it will have to do.

Now you can calculate a more predictable rolloff value with a very
simple formula. There are three unknowns in play: R, Capacitance C,
and the rolloff frequency F. If you have two of those you can find
the third.

What that means in this case: You know R = 10k. You choose a rolloff
frequency, maybe 1KHz. Then just plug those two values into this
formula to find the right value of capacitor:

C = 160,000 / (R * F)

In this case, that's 160,000 / (10,000 * 1000)

So your cap will be 0.016 microfarads for 1khz corner frequency.

If you want more rolloff, then of course you'd use a higher value cap,
but that should serve as a start. I like more mids, so I try not to
let high end rolloff extend down too far.

Also, using the series resistor, you should be able to get by with a
much smaller cap than 1uf. (BTW, you had a 1uf cap in stock? That's
not an electrolytic, is it? Try to use mylar caps for anything in the
signal path.)

[JimmyFly]

Wow great reply. I contacted Fishman last week and learned my measurement was off. The Powerchip volume pot is actually 20k linear as someone had pointed out in the forum earlier (so much info in here). I had asked the same question about a capacitor recommendation and no one has responded yet.

[mmmguitar]

Wow great reply. I contacted Fishman last week and learned my measurement was off. The Powerchip volume pot is actually 20k linear as someone had pointed out in the forum earlier (so much info in here). I had asked the same question about a capacitor recommendation and no one has responded yet.

Derek at Fishman replied with the following diagram they had on file - Though, unfortunately, it's not exactly what you're needing. There's a bit of irony in their prescribing a B250k pot in parallel with the preamp input; given I went through and "corrected" the posts in which I previously recommended that value!

Powerchip - Passive Tone.PDF

(106.19 KiB) Downloaded 486 times

The good news is that there are ways we can implement Fishman's approach: If you still have that 250k concentric pot you bought originally, you can bridge the outside pot lugs of whichever gang you want to function as volume with a 22k resistor; so that the piezo signal sees a 20K load. Note that this will affect the taper of the volume pot, somewhat - Alternatively, you can swap a carbon resistor track ranging between 100-250k from a donor pot into the concentric 10k pot you have. Bear in mind that the bottom gang of the pot will be controlled by the top knob; so it will come down to which orientation you're more comfortable with.

I drew up another Windows '98 Paint diagram for my idea with the resistor mod:

The Powerchip PCB-mount B250k volume pot is seated against a board component with double-sided adhesive - So be sure to use a thin blade or screwdriver to gently pry it off before desoldering the lugs from the underside of the PCB one at a time.

For anyone wondering why the tone pot schematic Fishman supplied doesn't have a capacitor: Piezo element signals are high impedance; meaning they're very weak and more dramatically affected by the resistance and capacitance values of the components the signal is being passed through. This is why most active piezo circuits have the preamp input as the first component in the path: An EQ'd, amplified, and buffered signal can be tailored to cooperate with more "typical" component values later in the signal path.

If you were to run a raw piezo signal through, for example, a 250k volume pot, that amount of resistance would act as a high pass filter and cut bass frequencies. If you were to run it through a tone pot with typical resistor or capacitor values, it would decrease volume, rather than roll off high frequencies. As described in the previous post, you can use an additional resistor in series with the tone pot input to tailor the rolloff frequency affected by the capacitor as the pot is turned down (Graph Tech's Acousti-Phonic preamp, for example, is designed to work with a standard .022µF tone cap, provided the piezo signal is seeing a 20k load via either 20k pot or a 250k pot with a 22k resistor added). In the case of the above Fishman diagram, the impedance of the 250k pot which causes bass frequency loss when the signal passes through it in series is being converted to a low-pass filter by way of having the pot-affected signal outputted in parallel along the preamp input path (hence the "ground" lug being combined with the output lug, rather than actually being sent to ground as in a volume pot configuration).

The one issue I have with Fishman's diagram is that I have have a hard time imagining whether the rolloff frequency is going to be ideal - I fear that firsthand experimentation and component value tailoring are going to prove necessary.

[JimmyFly]

Today was mod day for the PDF70. I exchanged the DuncanUSM's for the original Fly Dimarzios, replaced the stock saddles with Ghost Parker Piezo saddles and attached the unaltered Fishman powerchip. They work! To replace the Fishman 20k vol pot with a 250k concentric pot I revisited the forum only to find your new posting. This is great but I need some help with your concentric pot drawing. I'm guessing the top 3 lugs are the volume pot with the 22k resistor bridging the outside lugs. Where it says 'solder wires to old PCB connection' do I solder all 3 vol pot lugs to the old connections or just lugs 1 & 2? Assuming the bottom 3 lugs are the tone pot, how is the tone pot connected to the volume pot and is a tone cap used for this pot? As a test, before I remove the Fishman pot, could make the solder connections to the existing pot lugs in place and turn the volume off? Would that bypass the old vol pot? Thanks for all your help.

[mmmguitar]

I'm guessing the top 3 lugs are the volume pot with the 22k resistor bridging the outside lugs.

Yes.

Where it says 'solder wires to old PCB connection' do I solder all 3 vol pot lugs to the old connections or just lugs 1 & 2

All three. You're swapping a new volume pot 1:1 to the old pot's board connections, but with jumper wires bridging the space because the new concentric pot doesn't have PCB-mount lugs. You can have the resistor and Powerchip volume pot connections on the lower gang of the pot if it's easier for you to work with - But the piezo volume will be controlled by the top knob of the concentric pot.

Assuming the bottom 3 lugs are the tone pot, how is the tone pot connected to the volume pot and is a tone cap used for this pot?

I attempted to explain it in the previous post: Fishman is claiming that a 250k value pot is enough of a load on the raw piezo signal that it will act as a low-pass filter without a cap; provided you're using the left and center pot lugs summed together as the pot's output.

Even though the volume and tone pot are in the same housing, they're plugged in at two different spots in the Powerchip signal path:

Summed Piezos wire > Tone pot input [right] lug > bridged left and center/output lugs going to piezo-in solder pad on Powerchip > Volume pot connections on preamp.

You're inserting a tone pot in series between the piezos and the Powerchip, which then has the volume pot in series prior to its output stage.

As a test, before I remove the Fishman pot, could make the solder connections to the existing pot lugs in place and turn the volume off? Would that bypass the old vol pot?

I don't believe that would work. The volume pot wouldn't act as a bypass switch - When turned "down", it becomes a a shunt to ground for any signal in parallel with it (in this case, the new pot). And when it's "on", the resistive load of the two pots would be summed. Because I don't know if the Powerchip expects to see a particular resistive load from the pot in order to rout signal to the next output stage, I would desolder and remove the old volume pot completely as the first step. You can audition new components once you solder the three jumper wires to the pot connections on the preamp board.