Interesting Pickup Design from Fishman

[J M Fahey]

I love the geeky state of the art tecknoloky, kudos for it,plus the *new* idea.
Congratulations.

That said, I don't think it's better or different than a conventional round wire wound pickup, same amount of turns, same physical dimensions.
As in, being, say, 90% copper and 10% insulation, round copper is far more space efficient than PCB tracks, which are at most 50% space efficient (4 mil tracks on 4 mil spacing, 8 mil tracks on 8 mil spacing, etc.) .... and that *if* individual layer thickness is comparable, say 4 mil copper to copper layer separation and so on.

Meaning that a wirewound pickup will always easily match a PCB one, the opposite is not true.
Ok, maybe some day, but not in the close future.

All other factors remaining the same, of course, meaning magnets, preamp, mounting, active EQ, whatever.

Not dissing the design, quite the opposite, love it, simply that geometry tells me what I posted above.

FWIW: the main quoted advantage of absolute layer symmetry, important from the humbucking point of view, can easily be achieved in a wirewound pickup, just split the bobbin form in 2 , wind both at the same time which guarantees the same amount of turns, and connect one out of phase with the other.

[David Schwab]

Are you ridiculing me here?

Your comment was kind of dismissive, was it not? As if there's something inferior about active pickups. We can certainly say "just another single coil" about 90% of the Fender style pickups on the market, since there's absolutely nothing different about them.

I actually thought this was very clever, as are most active systems in one way or another. But regardless of this being active, the use of circuit boards intrigued me. I thought of trying this back in the 70s after looking at microwave guides that were etched into PC boards when I was at ITT.

[Joe Gwinn]

That said, I don't think it's better or different than a conventional round wire wound pickup, same amount of turns, same physical dimensions.
As in, being, say, 90% copper and 10% insulation, round copper is far more space efficient than PCB tracks, which are at most 50% space efficient (4 mil tracks on 4 mil spacing, 8 mil tracks on 8 mil spacing, etc.) .... and that *if* individual layer thickness is comparable, say 4 mil copper to copper layer separation and so on.

Meaning that a wirewound pickup will always easily match a PCB one, the opposite is not true.
Ok, maybe some day, but not in the close future.

All other factors remaining the same, of course, meaning magnets, preamp, mounting, active EQ, whatever.

The self capacitance will be far lower because the dielectric between copper is far thicker. This translates into a far higher self resonant frequency, 80 KHz if memory serves. This is high enough that transients are fully reproduced. The electronics can then pass them on or muffle them, as desired.

[John_H]

Your comment was kind of dismissive, was it not? As if there's something inferior about active pickups.

Yes, I'm sorry. I can't say it was made without prejudice. I haven't tried these so I don't have much right to judge them. I do see their merits, but I'm not a big fan of active systems. The technology of these is amazing. I question though the durability, reliability, and lifespan. Will they be affected by sweat, or just the degradation of the printed coils? How will they sound down the road? I know this doesn't mean much to many people in this disposable society that we live in, but it bothers me.

[Mark Hammer]

Excessive sweat has had its way with many a traditional pickup that has laid itselfopen to seepage, so these are not necessarily more susceptible. I haven't heard them in action (and join a very long lineup, there), so I may well end up saying "Interesting, but not my taste" in the final analysis. However, you raise an interesting point: how would one repair something like these? Or is part of the design concept a sort of "disposable coil"?

[Mike Sulzer]

Beautiful coils they are, but I think this capacitance issue is a red herring. Wind a coil with the same number of turns that these appear to have, and you get a resonant frequency well above 20KHz, as I think John_h pointed out. Furthermore, these are electric guitar pickups, unlike Fishman's other fine products. Electric guitar pickups do not have much in the way of high frequencies, because they resonate, rarely above 5 or 6KHz, usually below these days, and, anyway, the response of the speakers falls off a cliff at about 5KHz, as does the guitarist's hearing. Futhermore, for most rock, the high frequencies that present are quite intentionally from distortion, often after cutting highs from the pickup, and as for jazz, even though clean, the response hardly gets beyond the midrange. I thnk the claim we have heard here is that this coil design has low capacitance and therefore makes the pickup sound faster, even if you throw out the highs later with an active resonant filter to make it sound like an electric guitar. This is almost certainly an illusion, and I do not see why anyone would give it much credence without extensive double blind tests.

The self capacitance will be far lower because the dielectric between copper is far thicker. This translates into a far higher self resonant frequency, 80 KHz if memory serves. This is high enough that transients are fully reproduced. The electronics can then pass them on or muffle them, as desired.

[salvarsan]

Since I only glossed the Fishman article, I got the numbers wrong.
48 layers of 4 mil traces in .5oz copper gives ~1250 winds of something like 44 AWG at ~1400 ohms.
Some vendors list 3 mil/.5oz capabilities and unofficially brag of 2 mil/.5oz with a higher defect rate.
The 3 mil traces allow ~1500 winds, etc., etc.

[Mark Hammer]

Maybe so, Mike, but consider the possibilities of a pickup that could be mounted to an archtop, plugged into the board and sound more acoustic than you average pickup near the neck, and then do double duty as a mag-sounding pickup going to an amp with your average guitar-amp speakers (like the image of speakers "falling off a cliff at 5khz - one of the regularly forgotten realities!). That such potentially extended range is not usually used, does not mean it can't be used.

[charrich56]

+1 Mark, but Mike's point is valid as well. I'm really split between your posts.

If you have been able to listen to a truly high-fidelity magnetic representation of a set of vibrating steel guitar strings, you probably are aware that there can be definitely some things up in the audio stratosphere (10-20Khz) that you don't want - rinky, squinky, nasty things. Steel strings can go inharmonic way up there. Realistically we don't want much over 8-10 KHz for anything we know and love as an electrified acoustic tone, and a lot less bandwidth than that when pushing electronic distortion (tube, pedal, DSP) to avoid the dreaded "weediness".

However, that being said, some guy or gal in 5-10 years is going to want that ultra high-frequency crap out of a git-fiddle, and ring-modulate it with recorded whale calls to get "their" signature sound, or something like that. So if "we" don't go in that direction, someone else will, sooner or later. If it's audible or can be made audible, it can and most likely will be used in a musical context.

At the minimum, we do really want the medium high frequencies that normally get chopped off above the high-Z pickup's resonant peak. (back to your point.) At least get them out of the instrument and we can choose to make them part of the sound, or not. Once they're 25+ dB down with conventional mag pickups, they're effectively gone and you can't pay the price for EQ and gain to get them back because of noise and phase smearing.

All the "acoustic-ness", and probably the "openness," "speed," subjective qualities people try to hang whatever tag on, live up in the medium-high band, IMHO. People aren't used to hearing "acoustic-ness" from a "normal" magnetic guitar pickup signal at all because it mostly isn't there and what is there is highly filtered by the pickup resonance.

I do like the concept of the hybrid "acoustic"/magnetic guitar as in Parker Fly, Epiphone Ultra III, T-5, etc. but it's just such a royal PITA to deal with two completely different signal chains, amps, too many steenking knobs, etc.

So maybe we should be pointing in the direction of a baseline of what we <<can>> get out of the strings on the instrument, and out of the instrument, warts and all. I have no doubt that the new Fishman system system is going to be a step in that direction; how big a step remains to be seen.

Imagining myself with a million dollars and a clean sheet of paper, I would ask myself: "Can I get a clean, magnetically transduced, low-noise, flat-to-20K -response quality signal out of the instrument, through the cable, and all the way to the input of the outboard electronics, whatever they are?" The answer with current conventional hi-Z pickups is no. Even though those are the basis for the tones and sounds we grew up with and love.

We can't do it in the general case from a transducer design that is self-resonant in the exact frequency band we are trying to transduce. So any mag pickup (again IMHO) that can "do it all" is going to be low or medium impedance, regardless of coil construction.

If you can get that basic hi-fi representation of the strings out of the instrument, you can do anything else you want with electronics and DSP. And the size, weight, cost, and battery barriers to doing more of that in the instrument are going down all the time.

[Joe Gwinn]

Beautiful coils they are, but I think this capacitance issue is a red herring. Wind a coil with the same number of turns that these appear to have, and you get a resonant frequency well above 20KHz, as I think John_h pointed out.

True enough, but see later.

Furthermore, these are electric guitar pickups, unlike Fishman's other fine products. Electric guitar pickups do not have much in the way of high frequencies, because they resonate, rarely above 5 or 6KHz, usually below these days, and, anyway, the response of the speakers falls off a cliff at about 5KHz, as does the guitarist's hearing. Furthermore, for most rock, the high frequencies that present are quite intentionally from distortion, often after cutting highs from the pickup, and as for jazz, even though clean, the response hardly gets beyond the midrange. I think the claim we have heard here is that this coil design has low capacitance and therefore makes the pickup sound faster, even if you throw out the highs later with an active resonant filter to make it sound like an electric guitar. This is almost certainly an illusion, and I do not see why anyone would give it much credence without extensive double blind tests.

The issue of transient response is a fraught one.

One school of thought holds that one needs response to about 100 KHz to ensure that the attack transients are fully reproduced, and that this is important for achieving "transparency" (meaning that you could not tell a recording from a live performance in a double blind test).

The other school holds that this is all nonsense because the ear cannot hear above 20 KHz or so. But there is contrary evidence, but the effect isn't large. But the difference between very good and perfect isn't large either. And so on.

The issue is most important in the design of high fidelity recording equipment. In electric guitars, the issue is how well the attack transients need to be reproduced. I havent read any studies of this, but perhaps they do exist.

Based on the preferences for singlecoils for their clarity of tone, my opinion is that transient response does matter, but I cannot tell you how much is enough.

[Mark Hammer]

+1 as well. I constantly remind people that producing harmonics of harmonics of harmonics between pickup and amplifier power stage is decidedly not what anyone considers to be good tone. restraint the top end is normally a good thing...just not too much of it.

My qualifier would be that if one is using a system with an active electronic interface between pickup and whatever comes after the guitar, then it is a relatively simple and straightforward matter to jumper a few parts, flick a dipswitch, or whatever, and tailor the upper bandwidth to whatever one deems suitable. You can always trim back on what you don't want, but you can't fabricate what you never had to begin with.

[Mike Sulzer]

True enough, but see later.



The issue of transient response is a fraught one.
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Based on the preferences for singlecoils for their clarity of tone, my opinion is that transient response does matter, but I cannot tell you how much is enough.

My experience is that string harmonics (in the form of picking transients) of length of order of the spacing between the coils of a humbucker are clearly audible, on the #6 (low) E string, but not important on the #1 (high) E string. The latter are outside the bandpass of the system, and that would seem to be the obvious and complete explanation. (This is no criticism of the sound of humbuckers; different sounds are useful for different things.)

Who knows about this very wide band stuff. These very high harmonics primarily manifest as very fast rise and fall times. It would be very hard to demonstrate that the electronics responds perfectly linearly; if not the sound within the audible (as normally defined, 20KHz) bandwidth is affected.

[charrich56]

Hey, guys, I am going to go ahead and start a new thread on low (and medium)-Z pickups and onboard electronics.

[David Schwab]

That such potentially extended range is not usually used, does not mean it can't be used.

It would be great for bass! I posted a clip in the "Low and Medium Z Pickups..." thread with a sound clip of my old medium Z pickups I used to make. They had a very acoustic like quality to them because of the lack of the upper mid resonant peak.

Alembic guitar pickups have an extended high frequency response, and then they have variable low pass filters with adjustable Q to simulate the tones you associate with high Z pickups, etc.

[Joe Gwinn]

Who knows about this very wide band stuff? These very high harmonics primarily manifest as very fast rise and fall times. It would be very hard to demonstrate that the electronics responds perfectly linearly; if not the sound within the audible (as normally defined, 20KHz) bandwidth is affected.

It's not hard to demonstrate linearity in the electronics, even in the high harmonics. We demonstrate linearity in radar receivers working in the tens of GHz every day.

The real issue is how much the eay cares about these high harmonics and attach transients. Said another way, how much blurring of the transients is detectable, and how much is acceptable?