Interesting Pickup Design from Fishman

[Joe Gwinn]

But I do suspect that all those other articles that you mention have their flaws as well.

Yes, they all will, until someone figures it out.

Actually, it will never end, because human senses are so complex. But the models will get better and better, one breakthrough at a time.

[Rick Turner]

All interesting, and hi, Frank!

An aside...one of the three best musicians I've ever met is clinically deaf. Evelyn Glennie: How to truly listen - YouTube

And...I did a low z one layer pancake coil pickup a long time ago with the idea of getting the coil as close to the strings as possible...it's still a very interesting approach. Funny how the aspect ratio of some classic pickups makes them inherently less efficient as far as voltage goes. But there's tone there in the farther reaches.

I see pickups as having a very dynamic three dimensional quality to them. Any given coil mass/magnetic field shape will result in a certain signature tone. This is what I explored about 25 years ago winding classic bobbins...Tele, Strat, Humbucker, Rickenbacker, P, J, and Starfire bass coil forms with 7 x 44 Litz wire and winding the coils to approximately the original dimensions...not worrying about turns count. In spite of removing the coil resonance from the audible "picture", each now Low-Z pickup (in the 500 to 700 Ohms range) retained a certain signature tone. So coils (L,C,&R) are not the only way to mess with the sound. The physical relationships between magnetic field(s) and the coil(s) and the strings are incredibly important. The one thing that really surprised me about these pickups was how tight/fast/snappy the low end was. Cable designer George Cardas attributed that to the pickups having better group delay...so the issue of phase response rears it's lovely head again. I need to wind some more of those suckers, but tensioning Litz is a real pain in the ass...I guess I'll have to fix my magnetic drag tension wheel.

And yes, the whole idea of the variable low pass filters we used at Alembic was to be able to superimpose HiZ pickup resonance onto pickups that were coil-flat-response out past 20K.

[David King]

Hey Rick,
The Litz wire would be fun to mess with -for bass in particular. I'm dreaming of a PU that you could change the coil aspect ratio of easily. How hard could it be?
Back to Fishman, I doubt there is anything new reported here but I didn't read very closely.
Fishman Uses Technology To Revolutionize Guitar Pickups with Fluence

[charrich56]

Rick,

Thanks for chiming in on this thread. I think your thread on the "1000 turn pickup" http://music-electronics-forum.com/t23153/ got misunderstood and as a result ended up the weeds for the most part, not your fault at all. Your primary points there and in your last post are very valid IMHO and were/are not lost on some of us.

To freely rephrase part of your previous thread if I understand your points correctly, let's just hear the sound of the magnetics interacting with the strings without the traditional pickup resonance getting in the way, and get a clean signal out of the instrument so we can hear what's really going on with the pickup design as designers, and also performance-wise, so that we have the most musical information to send to the downstream electronics. Yes, captain, I concur. 8-)

(Inference from your last post) There's a lot going on for any given basic design, strings/magnet/coil/dimensions, etc. that we simply just don't hear with traditional hi-Z pickup construction/winding.

Just as a related point, I used to think that you really need some high frequency cutoff, and maybe even a resonant peak, in the pickup itself to make distortion/overdrive work right, but after experimenting with a low-Z Strat set in my test dog guitar into Amplitube 3 (I can't afford a boutique amp collection right now), I am starting to think that that isn't as much of a factor as you might think although rolling off some highs is probably a good thing for higher gain/OD playing if the stompbox or amp won't do it on its own.

A low-Z, just neck, or neck+middle Strat sound, for example, through a quality FET or tube preamp into a good amp or amp model, "clean" up to the edge of "crunch" region distorted, has to be heard to be believed. I can't really think that the Fishman Fluence would sound much better although it might be more flexible.

(you do have to turn the treble and bass down if the amp or model has a Fender/Marshall/Vox tone stack, though)

Thanks so much for your contributions to this forum and your other trailblazing efforts over the years, Rick.

I will be playing with an 8/44 Litz humbucker pretty soon. The 7/44 is hard to come by on Ebay. 8-)

-Charlie

[Rick Turner]

Charlie, you understand my points precisely. Many (most?) pickup winders are so focused on the wind count, inductance, and/or the specific magnet formula that they ignore the whole issue of the shape of the field as it changes dynamically with string vibration and how that generates the current in the coil...or even down to the various layers and winds in the coil. There are other important and other subtle things going on. There is even an audible difference between a low Z Tele neck pickup and a low Z Strat pickup, as close as the build geometry and material selection usually is between the two. Why? Well, it ain't the coil LCR measurements!

Another worthy experiment would be to wind some classic single coils, but squeeze the bobbins together at the top so you've got about an 1/8" gap in which to wind...real pancake coils. Wind another one with the bobbins squeezed together at the bottom. Test output at a constant distance from the strings. How much more output is there from the
coil at the top pickup versus the coil at the bottom version? That'll tell you something you might want to know.

How effective can pole pieces be in bringing flux variations closer to farther away coil turns? I can tell you that my Rick horseshoe pickup coils...yes, done my way with Alnico magnets instead of bit off nails, using the horseshoes as pole pieces...the full assembly has significantly more output than the pickup just used as a large Fender-style single coil. Why? I think because the horseshoes are bringing some flux fluence action down to the lower coil windings.

Hey, I got to use that word with a small "f"! Though "flux fluence" sounds kind of like flatulence...

[bbsailor]

Charlie, you understand my points precisely. Many (most?) pickup winders are so focused on the wind count, inductance, and/or the specific magnet formula that they ignore the whole issue of the shape of the field as it changes dynamically with string vibration and how that generates the current in the coil...or even down to the various layers and winds in the coil. There are other important and other subtle things going on. There is even an audible difference between a low Z Tele neck pickup and a low Z Strat pickup, as close as the build geometry and material selection usually is between the two. Why? Well, it ain't the coil LCR measurements!

Another worthy experiment would be to wind some classic single coils, but squeeze the bobbins together at the top so you've got about an 1/8" gap in which to wind...real pancake coils. Wind another one with the bobbins squeezed together at the bottom. Test output at a constant distance from the strings. How much more output is there from the
coil at the top pickup versus the coil at the bottom version? That'll tell you something you might want to know.

How effective can pole pieces be in bringing flux variations closer to farther away coil turns? I can tell you that my Rick horseshoe pickup coils...yes, done my way with Alnico magnets instead of bit off nails, using the horseshoes as pole pieces...the full assembly has significantly more output than the pickup just used as a large Fender-style single coil. Why? I think because the horseshoes are bringing some flux fluence action down to the lower coil windings.

Hey, I got to use that word with a small "f"! Though "flux fluence" sounds kind of like flatulence...

Rick,

The Rick horseshoe pickups place the string in the center of a magnetic field both above and below the string. This should produce a more symmetrical output than traditional pickups with a magnetic field only below the string where the output is higher when the string approaches the magnet and is lesser when in an upward position away from the magnet. Placing another pickup inverted on top of a body mounted pickup with the string going between
the two coils and magnet sets will also produce a more symmetrical output.

Let me take a stab at why the Tele neck and the Start neck Low Z pickups sound different.
1. Magnet size and type and related bobbin shape
2. Wire gauge difference
3. Metal cover on the Tele neck pickup

Thanks for your observations.

Joseph Rogowski

[frankfalbo]

Great to see you here Rick, I miss talking shop with you and I know you'd get a huge kick out of seeing how this project came together.

...Another worthy experiment would be to wind some classic single coils, but squeeze the bobbins together at the top so you've got about an 1/8" gap in which to wind...real pancake coils. Wind another one with the bobbins squeezed together at the bottom. Test output at a constant distance from the strings. How much more output is there from the coil at the top pickup versus the coil at the bottom version? That'll tell you something you might want to know.

With the layer by layer build of these coils we've got the data down to the layer. They can tell you the dB gain of each layer, which teaches the distance relationship. In the stacked single design the bottom coil is nearly deaf. But unlike a wire-wound stack in which the phase anomalies are resented, these anomalies and associated combing are welcomed, because the top coil is so dense and rich. The bottom coil's minuscule add to the sound is all positive, considering we like the way good Strats sound.

But you are also right as to the magnetic circuit's role in the harmonic content and comb filtering, in that for every low E string sound (Strat for example) the A and D pole are contributing off-axis audio as well. A blade doesn't do nearly as much damage to the content. (Damage being a good thing for a Strat embodiment) And their stray flux is immense. It's like a sneeze. It's everywhere.

How effective can pole pieces be in bringing flux variations closer to farther away coil turns? I can tell you that my Rick horseshoe pickup coils...yes, done my way with Alnico magnets instead of bit off nails, using the horseshoes as pole pieces...the full assembly has significantly more output than the pickup just used as a large Fender-style single coil. Why? I think because the horseshoes are bringing some flux fluence action down to the lower coil windings.

Hey, I got to use that word with a small "f"! Though "flux fluence" sounds kind of like flatulence...

You would love talking to the magnetics expert who designed the coils. Its true and we did a lot of experimenting to consider how you can "tickle" the turns that are otherwise out of usable range. Traditional pickup designs are far from saturated. But that's not to say more saturation is always better, it generally densifies the tone but sometimes it's those "tree branches with no leaves" that are responsible for creating that harmonic structure we've come to love.

[Rick Turner]

Joe,

One out of three!

1. Yep...Magnet type (hmm...maybe), size, and bobbins are slightly different. Yes, and that's what I learned and that's my point.

2. Nope...used the same 7x44 Litz, and the winding count puts audible resonance in the bat range

3. Nope...in this case I left the metal cover off, though it would be interesting to see and hear if the losses in the cover would be audible if the coil is so low Z

And "yes" on the more symmetrical field thing. I've made some little dual blade single string pickups with the coils oriented at right angles to the strings with pole pieces that come up on either side of the string. Pretty interesting...symmetrical field for the string, kind of push/pull operation, great response to attack since 95% of the time, the strings are first excited parallel to the face of a guitar or bass.

Frank...yeah, I was figuring that with these layers of precise "coils" you could really have some fun with the distance thing. And I like that term "tickling" the turns...That whole thing is of greater interest to me than winding resonant coils...though that is also interesting. But the tickle factor is a far greater mystery than measuring LCR factors which are extremely well understood...at least here. I also fully "get" that it may be desirable to wind (or stack) turns farther away from the strings for tonal reasons even if they don't contribute much to the voltage output. Those turns are going to be the spices in the magnetic tonal stew. The meat is up at the top. I guess the veggies are in the middle...

And quick disclaimer...for a while, Frank and I were pretty much on the same team...Frank working at Seymour Duncan and me being a partner (now ex-partner) in Duncan Turner Acoustic Research. I also have a set of three of the Zephyr humbuckers that Frank was instrumental in helping to develop; the pickups are going to go on a repro of an SG/LP necked guitar that I put together in 1967 and later sold to Jerry Garcia. I got a wrecked body (intact neck!) '61 or '62 LP(SG) custom, made a body for it, and used it as my main guitar playing in a band in New York. Garcia used the guitar in '71 and it's on Live Dead. I think the Zephyr pickups are going to sound just wonderful on the repro...Thanks, Frank!

And a quick aside...Alexander "Howard" Dumble suggested that I try winding some pickups with silver wire in about 1985. Never did. The cost of the wire was staggering...

[charrich56]

You would love talking to the magnetics expert who designed the coils. Its true and we did a lot of experimenting to consider how you can "tickle" the turns that are otherwise out of usable range. Traditional pickup designs are far from saturated. But that's not to say more saturation is always better, it generally densifies the tone but sometimes it's those "tree branches with no leaves" that are responsible for creating that harmonic structure we've come to love.

Frank, that's an interesting point about the bottom coil actually being useful to deliberately "tone down" or weed out some of the signal harmonic density, if I can call it that, from the top coil, and not just cancel hum. I believe that the Kinman and DiMarzio stacked single coil sized 'buckers may use that strategy as well, also reached by lots of experimentation most likely.

Designing for magnetically "tickling" the bottom coil versus partially shielding it via fancy combed magnetic shields (aka flux conductors), looks like two approaches to the same basic goal you're talking about. It's still a very cool and interesting area to work in. If we had truly audio frequency-selective magnetically permeable materials, this stuff might be a lot simpler.

But even if you make the best stacked coaxial humbucker possible, there are still other approaches that wouldn't necessarily require that amount of engineering to get good to great results. Rick's horseshoe, side by side and sidewinder humbucker designs, Scott Lawing's Zexcoil, etc. As long as you go low to medium impedance. (sorry, my soapbox again.)

I'm only saying this because I think there is a huge area of development and experimentation still left in the pickup design space, and I suspect that maybe some of the visitors to this thread might be feeling similar to how a skilled slide rule craftsman might have felt in 1972 when he/she got a good look at the Hewlett-Packard HP-35 scientific calculator.

If the Fluence shakes up a few pickup makers and gets them thinking in new directions instead of lockstep, cork-sniffing homage to the past, then that's a good thing IMHO. There's still going to be a market for vintage type pickups for quite a while though, unlike slide rules.

As you said Frank, it really must have been a gas (no follow-on humor intended, Rick) to be associated with and work with the Fluence project.

-Charlie

[Rick Turner]

Hey, I still have my 1973 HP-35 in the back of a drawer somewhere! I wonder if it still works... That sucker was $425.00 back then...holy mackerel...Dollar Times says that's $2,409.87 in 2014 bucks. I'll have to see if it's a collectible yet. It is post CBS, though...

[bbsailor]

Joe,

And "yes" on the more symmetrical field thing. I've made some little dual blade single string pickups with the coils oriented at right angles to the strings with pole pieces that come up on either side of the string. Pretty interesting...symmetrical field for the string, kind of push/pull operation, great response to attack since 95% of the time, the strings are first excited parallel to the face of a guitar or bass.

Rick,

One quick way to hear the difference between the initial string attack being either parallel with the pickup top or perpendicular to it is to do the following.

Pinch the string right above the pickup pole piece and lift it between .125" to .25" and release it. Then, pinch the string and pull sideways so the initial attack is now parallel to the pickup top. Listen and observe the initial attack on an oscilloscope. There is a very definate difference.

Here is another interesting thing to try. Tape small .187" diameter magnets next to the two e-strings on the outside of the pickup cover to provide a broader magnetic field to the end strings. If you locate small neo ring magnets, with a center hole near the size of the pickup mouning screw, you can place the modification on the Strat pickup mounting screws to make a more permanent and neater installation.

My latest experiment with litz wire is to use a Prem Magnetics SPCT251 current transformer with a .160" square opeening for the user to install the primary turn. I have used AWG 6 square copper wire (about 30 micro ohms per inch from Surplus Sales of Nebraska) to make the primary string loop. Then I will use the litz wire concept to place as many AWG 16 wires individually joined as separate loops that will fit in the same .160" primary opening space.

The output of a current transformer is very sensitive to the current being generated in the primary string loop. Even a little skin effect at the higher frequencies seems to limit the upper harmonics output.

Joseph Rogowski

[Rick Turner]

Joe, when Lane Poor worked for us at Alembic...circa 1975 or so, we played around a bit with what Lane was calling "quadrature" coil arrays. Basically, it was two coils per string set up so the coils were in a "V" formation @ 90 degrees to one another set 45 degrees to the plane of the guitar or bass top.

I got into the mini sidewinders with the N/S blades for potential synth pickup use; they're "fast" since the string attack is usually parallel to the top. Then I got into individual string piezos which have some significant advantages all around. Just got my first 3D printed parts for piezo bass saddles, and this is a good thing! Whales to bats frequency response...

[charrich56]

I was going to get an HP-35 for a HS graduation present in 1973, but decided that I wanted a guitar instead. My dad bought me an Electra Super Rock LP copy at Swicegood Music in Beaumont, Texas. My, was it sure purty. I still have the neck to that guitar.

Knowing what I know now, I would have held Dad up for a real Gibson. The dentist's kid in my town got a Les Paul Recording at about the same time, that he probably still has. Curiosity about what the hell that guitar was actually started me looking at low impedance a long time ago. I always could play better than he could, though, even though he had a cooler (to me) guitar. 8-)

-Charlie

[Rick Turner]

I'd just like to point out that with regard to stuff happening above 20 K Hz, if it's not there due to limitations in transducers or the amplification chain, then you can't have a 30 K wave interacting with a 25 K wave and producing a totally audible 5 K wave form as a sub-harmonic from wave interference...cancellation and reinforcement. And you can hear that stuff...

In about 1980 or so, I went to the "High End Hi-Fi Show" in Santa Monica with my friend and audio/electronics genius Bob Wolstein who was doing some design work with me at Gibson Labs. Bob and I went on to found Highlander Musical Audio...'nuff said. We went from room to room listening to an amazing selection of the best of the best of the audiophile world at that time. Vinyl, CD's, analog tape, $75,000.00 to $150,000.00 systems with cables that cost more than my Volvo... And I came away with an understanding/feeling about that current state of the art of 44.1 K CD sound. To me, it sounded as though there was but one high-hat in the entire world, and it was Fed-Exed from a session in London to Kingston to LA to New York to Paris or wherever the fuck. All the detail of highhats and cymbals had been reduced to one basic sound. How? Why? Well, Bob and I theorized that we were hearing a kind of quantizing...the digital clock was taking over and superimposing it's time base onto what was happening in the natural world. WTF? Hey, you can't hear 44.1 K! Yeah, but maybe you can hear it's effect on stuff well within the audio band...

And so I tend to believe that while we may not directly hear stuff at or above 20K, we may miss it when it's gone because of its effects down below.

And I've also come to believe that if you fuck with the slew rate, you can hear that in the low end. Bass becomes less defined. The impact is lessened. I think that's what I hear in the difference between "normal" and the Litz wire pickups, and it's what George Cardas identified as being the audible group delay issues.

I still think there's stuff we...or at least really sensitive listeners...can hear for which we've not yet developed adequate "scientific measurements". Yes, I believe that some folks can hear what science hasn't yet adequately quantified. That was certainly true in my career 40 years ago when engineers truly thought that THD was indicative of the subjective audio quality of an amplifier. Turned out to be at least one misleading spec. Now it seems that slew rate is more important...

And so, too, this pin-point focus on coil resonance. It's just one part of the picture, albeit one that anyone can easily measure now. But are we interested in what is basically an EQ curve superimposed upon a simplified model or do we want to know what the string is doing with and to a dynamic 3D magnetic field? I'd say we want to know both in order to be able to tweak the results. But you have to at least intellectually separate the effects that are going on. And, yes, it's complex...but you're never going to get "there" winding and listening only to high Z pickups.

I think that if you can understand what you hear with LowZ pickups, you'll be much better at then EQ'ing/filtering them in the High-Z realm. In other words, if you can't hear the 3D magnetic dynamics as a separate issue from what I now see as the dumb-ass simple LCR coil resonance factors that anyone can measure, then you can't take magnetic pickup design into the next level. Or...for that matter...even completely understand the past 80 years of mag pickup design.

BTW, our craft/art/science goes back into the 1920's. Henry Kurmeyer brought out the first commercially sold magnetic pickup equipped electric guitar in...yep...1928. He was the K of Kay and also had Stromberg-Voisinet. Lloyd Loar debuted mag pickup bridge sensitive instruments in 1933 with the ViViTone line...I have what may be the 3rd of those guitars, and I restored the electronics on his personal electric viola...circa '31-33. The Kay and ViviTone pickups tried to sense the top or the bridge, and it didn't work too well. Rickenbacher, of course, came out with the first successful "string sensitive" pickup and that's pretty much how it's been ever since...with some really interesting variations.

Still, if you're limiting your understanding of the sound of magnetic pickups to the resonant filter of the coil, you're doing yourself a serious dis-favor. It may be the easiest factor to understand, but it's not the only "game in town".

And be wary...but not totally disbelieving...of golden ears. Yes, there's a lot of utter bullshit in the high-end of hi-fi. And then there are those who do truly hear what hasn't been adequately measured or quantified...yet. One of "Our Jobs" is to take care of those omissions and add to the scientific rigor. And I'll be the first to say "I don't know"..."but I'd like to."

[frankfalbo]

And so I tend to believe that while we may not directly hear stuff at or above 20K, we may miss it when it's gone because of its effects down below.

...and it's what George Cardas identified as being the audible group delay issues.

...Now it seems that slew rate is more important...

And so, too, this pin-point focus on coil resonance. It's just one part of the picture, albeit one that anyone can easily measure now. But are we interested in what is basically an EQ curve superimposed upon a simplified model or do we want to know what the string is doing with and to a dynamic 3D magnetic field? I'd say we want to know both in order to be able to tweak the results. But you have to at least intellectually separate the effects that are going on. And, yes, it's complex...but you're never going to get "there" winding and listening only to high Z pickups.

I think that if you can understand what you hear with LowZ pickups, you'll be much better at then EQ'ing/filtering them in the High-Z realm. In other words, if you can't hear the 3D magnetic dynamics as a separate issue from what I now see as the dumb-ass simple LCR coil resonance factors that anyone can measure, then you can't take magnetic pickup design into the next level.

I've highlighted all of the "high five" moments. Please place hand on screen after each segment.

My favorite part is helping on the magnetic circuit side. The prominent wins of course were sitting around the room with all the respective ears when developing the response curves, watching everyone's elation when a/b'ing against known superlative examples of everything we love. But you can do that, and still have a misfire on the dynamics, and the listener won't know it. Only the player (or someone who really knows how to watch a player while interpreting what they hear) will sense it. Its when everyone was talking about how amazing they feel when I knew we accomplished something big.

The Zephyrs are the same way. When you load them in, and hear the speed, the alignment, all of those things that are vague to the listener but unmistakable to the player; what a payoff. The Fluence core is the highest "def" picture I've ever heard taken of the string.