frankfalbo
Meter Reader 1st Class
Posts: 74
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Post by frankfalbo on Mar 18, 2017 18:40:05 GMT -5
"Compound that by the comb filtering associated with one lone pole..." A lone pole piece does not produce comb filtering. It causes an attenuation of the higher harmonics in the string motion as determined by the pattern of string magnetization that it excites, and the component of the resulting flux along the coil axis. Who are you to decide which statements that you make are the ones I consider absurd? That is a rhetorical technique as subtle as Trump on twitter. You avoid answering legitimate questions about what you write, and claim that is because you are a working professional. Then what are you doing here if you cannot actually say anything? I did nothing of the sort. I offered some preemptive clarifications to some things I thought you might have meant. It's not a technique. You're projecting something that doesn't exist (or I didn't intend) on my end. So let's isolate what you quoted. I believe you're using the term comb filtering solely as it relates to the string window; the Tillman article. I'm referring to the comb filtering that occurs within a coil as it relates to the return path, and the proximity of the turns to the strings. If you believe the latter doesn't exist, then I'm powerless in that matter. Comb filtering does very little to the overall dB reading, so an amplitude plot that attempts to show how large the string window is, or establish parameters for how to define the string window, it's not that relevant. But as it relates to the sound associated with it, and the descriptive terms associated with the user experience, it's not that cut and dry.
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Post by antigua on Mar 18, 2017 18:52:54 GMT -5
In the interest of fact based findings, here are screen shots I took with my phone, using an FFT audio analyzer app: In my music room I have a drum kit and some guitar amps. I hit the ride cymbal and captured this, showing lots of acoustic content up to and beyond 16kHz: Then I plugged a Tele into an Orange Rockerverb, played clean, with the treble cranked, played some chords and captured this: I'm impressed how, in general, they resemble the response plot of the Celestion Green Back plot:
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Post by antigua on Mar 18, 2017 18:54:25 GMT -5
So let's isolate what you quoted. I believe you're using the term comb filtering solely as it relates to the string window; the Tillman article. I'm referring to the comb filtering that occurs within a coil as it relates to the return path, and the proximity of the turns to the strings. If you believe the latter doesn't exist, then I'm powerless in that matter. What was the moment at time in your life when you concluded that inner-coil comb filtering was a thing? What experiment or piece of information "sealed the deal", for you? That is information that would be useful to me.
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Post by Charlie Honkmeister on Mar 18, 2017 18:57:52 GMT -5
Look, we all know where this is headed. I work for companies and I'm not posting graphs or screen shots, or going down too many rabbit holes with you guys. There are uninformed and downright false claims made in the name of science emanating from these kinds of homebrew experiments, and dismissive unbelief in other areas. You run these flawed experiments and then sprint to the nearest pickup forums to blast your newfound knowledge as if it's canon. It's killing me to watch some of you take this hobby of yours and turn it into a crusade. It's like I'm watching a kid first learn what salt and pepper taste like, and then they proceed to describe everything as "salty" or "peppery" to the entire world...until they learn about garlic. You pick and choose what you will listen to, such as an article by a dealer that says 5k+ doesn't matter in a guitar speaker, but you refuse to consider return path issues because the gauss meter zeros out at some point. Well, zero isn't zero on that meter. That meter is a bull in a china shop for what you're trying to determine. No, it's a bull in a dollhouse. It's Godzilla. If you think 5k is a cutoff, stick a 31-band EQ in the effects loop of your Mesa Triple Rectifier and boost 16kHz and see what freaking happens. Does nothing happen? Is the cabinet deaf to 16k? Map out the Q of the 16k fader and see how low it goes. The FACT is, I work with pickup technology where I can literally touch a button during the R&D process and toggle <1dB at 10kHz and everyone in the room hears the difference, and has an opinion about it. Of course It does different things with different amps, but for example I can pinpoint the exact moment on a Marshall where it goes from ear candy, to crashing the preamp. Yet some of you want to take what I'm saying as a lie, or as "unproven" because you're not on my R&D team and you didn't see it for yourself? I've done the string window studies. There are flaws in what you're going to conclude from this. You can either keep going and ignore what I'm trying to tell you, post up counterpoints to every one of my points, or consider them. Frank, string window and Gauss meter comments aside, do any of the commercial pickups/systems you have worked on, incorporate the stated and/or implied results of your R&D involving either direct audibillity of signals in the 5Khz-15KHz+ range, and/or interaction of those frequency components with tube guitar amplifier preamp, intermediate driver/phase inverter, or power amp/speaker stages? I'm only aware of your design input on the Seymour Duncan Zephyr and Fishman Fluence products. Would it be possible in theory to test one or both of these products in some form factor, and be able to verify what you are saying?
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Post by ms on Mar 18, 2017 19:14:50 GMT -5
"Compound that by the comb filtering associated with one lone pole..." A lone pole piece does not produce comb filtering. It causes an attenuation of the higher harmonics in the string motion as determined by the pattern of string magnetization that it excites, and the component of the resulting flux along the coil axis. Who are you to decide which statements that you make are the ones I consider absurd? That is a rhetorical technique as subtle as Trump on twitter. You avoid answering legitimate questions about what you write, and claim that is because you are a working professional. Then what are you doing here if you cannot actually say anything? I did nothing of the sort. I offered some preemptive clarifications to some things I thought you might have meant. It's not a technique. You're projecting something that doesn't exist (or I didn't intend) on my end. So let's isolate what you quoted. I believe you're using the term comb filtering solely as it relates to the string window; the Tillman article. I'm referring to the comb filtering that occurs within a coil as it relates to the return path, and the proximity of the turns to the strings. If you believe the latter doesn't exist, then I'm powerless in that matter. Comb filtering does very little to the overall dB reading, so an amplitude plot that attempts to show how large the string window is, or establish parameters for how to define the string window, it's not that relevant. But as it relates to the sound associated with it, and the descriptive terms associated with the user experience, it's not that cut and dry. If you think there is a comb filter relating to the return path of the flux, please show some evidence, either theoretical or experimental, or better yet a combination of both. You might start by better defining what you mean by "a comb filter relating to the return path."
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frankfalbo
Meter Reader 1st Class
Posts: 74
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Post by frankfalbo on Mar 18, 2017 20:49:32 GMT -5
Frank, string window and Gauss meter comments aside, do any of the commercial pickups/systems you have worked on, incorporate the stated and/or implied results of your R&D involving either direct audibillity of signals in the 5Khz-15KHz+ range, and/or interaction of those frequency components with tube guitar amplifier preamp, intermediate driver/phase inverter, or power amp/speaker stages? I'm only aware of your design input on the Seymour Duncan Zephyr and Fishman Fluence products. Would it be possible in theory to test one or both of these products in some form factor, and be able to verify what you are saying? I'll do what I always do, which is to share anecdotally but I can't give a 360° tour of a multi-year R&D project funded by companies who have earned the right to do so over decades of discovery and fair commerce. (I'm not suggesting that's what YOU are asking, just that it's a common theme) To answer the question directly, Fluence is the most obvious project, in that one thing I've mentioned publicly in the past (without revealing final iteration data) is that the original Fluence core had a resonant peak of 80kHz. I have the full spectrum at my fingertips during the voicing process. I can literally listen to the difference 1dB at 10kHz makes in realtime. Same is true of 16k, et al. Now, if you run a simple plot of a Fluence vintage Strat voice against a 54 Strat pickup they'll be pretty similar. Whether or not subtle differences are meaningful, or whether someone thinks they're not worth spending money is up to the consumer. But they're not imagined or conjured. As far as Zephyrs were concerned, we felt the subtle differences did manifest themselves north of the resonant peak, and in the time alignment/group delay. They will also not provide any chart or plot that verifies it and I do not work for them anymore.
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Post by ms on Mar 18, 2017 21:00:36 GMT -5
Frank, string window and Gauss meter comments aside, do any of the commercial pickups/systems you have worked on, incorporate the stated and/or implied results of your R&D involving either direct audibillity of signals in the 5Khz-15KHz+ range, and/or interaction of those frequency components with tube guitar amplifier preamp, intermediate driver/phase inverter, or power amp/speaker stages? I'm only aware of your design input on the Seymour Duncan Zephyr and Fishman Fluence products. Would it be possible in theory to test one or both of these products in some form factor, and be able to verify what you are saying? I'll do what I always do, which is to share anecdotally but I can't give a 360° tour of a multi-year R&D project funded by companies who have earned the right to do so over decades of discovery and fair commerce. (I'm not suggesting that's what YOU are asking, just that it's a common theme) To answer the question directly, Fluence is the most obvious project, in that one thing I've mentioned publicly in the past (without revealing final iteration data) is that the original Fluence core had a resonant peak of 80kHz. I have the full spectrum at my fingertips during the voicing process. I can literally listen to the difference 1dB at 10kHz makes in realtime. Same is true of 16k, et al. Now, if you run a simple plot of a Fluence vintage Strat voice against a 54 Strat pickup they'll be pretty similar. Whether or not subtle differences are meaningful, or whether someone thinks they're not worth spending money is up to the consumer. But they're not imagined or conjured. As far as Zephyrs were concerned, we felt the subtle differences did manifest themselves north of the resonant peak, and in the time alignment/group delay. They will also not provide any chart or plot that verifies it and I do not work for them anymore. What do you mean when you say a core has a resonant peak of 80KHz?
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frankfalbo
Meter Reader 1st Class
Posts: 74
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Post by frankfalbo on Mar 18, 2017 21:07:22 GMT -5
What was the moment at time in your life when you concluded that inner-coil comb filtering was a thing? What experiment or piece of information "sealed the deal", for you? That is information that would be useful to me. Well I didn't fall and hit my head and wake up with a flux capacitor drawing. But I can tell you it's post-Duncan, Fluence-era. The Fluence core is extremely revealing in that, by being one full coil per vertical layer, all I can say is that it allows us to see things that are more difficult to see with a wire-wound coil. But it also proved out some theories and demystified some voodoos. With a peak that high for example, there are things we can see in isolation. Like swap Ceramic for Alnico with zero shift in frequency response from coil resonance. Stuff like that. As for what I refer to publicly as phase anomalies within a wire-wound coil, if we remove the effect of the return path from the equation it's loosely tantamount to setting up 3 mics, each behind the other. To a much smaller degree that happens throughout the height of a coil, which I can see layer by layer with a Fluence coil. Bill Lawrence was playing in that field with his microcoils.
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Post by stratotarts on Mar 18, 2017 21:19:37 GMT -5
Frank, I believe that when there are flaws in the reasoning or experimentation that appears here, we are very open to having them pointed out. But it's not fair, or good science, to expect any opinions to change without presenting any concrete arguments or data. In fact, most of us have had a few occasions of being in need of correction. It is healthy. I like this forum a lot because of the gracious exchange of criticism. However, it has become almost an unwritten law here that arguments and theories need objective support. In this matter, there is a fundamental incompatibility between proprietary, private research and the open, public exchange that goes on here. I think it is because of the skeptical scientific background that many of us here have. You may consider our efforts amateurish - it is your right to an opinion. However, it doesn't carry much weight when you are unwilling to clearly demonstrate the basic facts of your own efforts here. To flaunt them and refuse to back them up simultaneously, is a contradictory behaviour that benefits nobody.
I have no automatic respect for R+D teams and expensive equipment. Of course they're wonderful. But they don't gain you any more academic or actual credibility in of themselves. It's how they are used that is potentially powerful. In fact, when they're convoluted with strong pecuniary interests and strong egos, they frequently steer the ship of truth off course. Think Pons and Fleichmann. Or many drug manufacturer funded product safety studies. Or the lunatic fringe - the free energy folks and so on. What they mainly lack is transparency and a healthy balance of competitiveness and information sharing. Also a healthy respect for the need for rigorous, thoughtful and well designed experimental procedures to support theory.
So, if you have specific criticisms against any of our thinking or procedure, the appropriate response is to respond with scientific data in the common vernacular of engineering, not rhetorical gestures or synthesized jargon that only you possess the full meaning of. Some of your comments in this thread border on insulting. You should consider how that affects your public image if you are in this as a career.
Edit - also you make reference in several places to listening tests. These are notoriously susceptible to psychological biases, and have no credibility unless a tight regime of safeguards are employed. Unless you can assure us that these were randomized, double blind tests with a sufficient sample size to be statistically valid, it would be foolish to pay any attention because of the long history of inattention to these important factors in this field.
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Post by antigua on Mar 18, 2017 21:53:59 GMT -5
More test results: Here is the same test as before, but this time the A string was used instead of the G string: AlNiCo, A string | offset mm | 0 | 3 | 6 | 9 | 12 | 15 | height mm | | | | | | | | 3 | | -24.5 | -27.1 | -38.9 | -47.5 | -46.7 | -46.8 | 6 | | -38.4 | -38.9 | -41.8 | -44.3 | -48.8 | -49.7 | 9 | | -42.4 | -40.6 | -40.7 | -48.1 | -49.5 | -49.8 | 12 | | -44.7 | -44.3 | -45.1 | -45.3 | -45.6 | -45.8 | 15 | | -44.7 | -45 | -45.1 | -45.5 | -45.6 | -49.8 |
Even with the A string, the same pattern emerges, with a sort of flat response across a certain width. The is about a +/- 2dB margin of error, the number bounces around by about that much, and I input the value that I happen to see the moment I look up at it. Sometimes I try to average it if I can, but it's not super easy, so if something doesn't make sense, but a 2dBm error would explain it, that's probably what happened. There's also a general sort of unpredictability around -45dBm, maybe it's a noise issue, I'm not sure. ==========--==---=---------------=---=------------ - - -- --------- - - - - - -- - Next, I went back to the G string, still using the same AlNiCo, but I pressed it out 3.5mm to approximate a tall stagger: Al. G w/ 3.45mm stagger | offset mm | 0 | 3 | 6 | 9 | 12 | 15 | height mm | | | | | | | | 3 | | -28.7 | -28.9 | -33.5 | -39.9 | -46 | -46.2 | 6 | | -35.3 | -35.5 | -38.7 | -42.7 | -46.2 | -47.5 | 9 | | -41.3 | -42 | -42.5 | -45.1 | -47.5 | -48.1 | 12 | | -44 | -44.5 | -45 | -46 | -46 | -46 | 15 | | -45 | -45 | -45 | -46 | -46 | -46 |
The very interesting thing here is that now there appears to be a "wide" window at 3mm, where as with the pole piece flux, the "wide" window didn't emerge until 6mm. This suggests that it's the coil's distance from the string is more operative in establishing that "wide window" than the proximity of the pole piece, because the pole piece is about 3mm from the string, but the coil is a bit over 6mm away. Here's is a pic of the stagger: ==========--==---=---------------=---=------------ - - -- --------- - - - - - -- - Next, here is the test, over the G string again, with a steel pole piece and one neodymium tab on the other side. The Gauss reads 400G at the business end of the pole piece: steel w/ 1 neo | offset mm | 0 | 3 | 6 | 9 | 12 | 15 | height mm | | | | | | | | 3 | | -19.3 | -21.4 | -27.7 | -38.8 | -44 | -46.7 | 6 | | -26 | -27.2 | -31.2 | -41.3 | -44.8 | -46 | 9 | | -34.2 | -35.0 | -37.8 | -41.2 | -44.5 | -45.1 | 12 | | -38.3 | -39.4 | -40.9 | -42.7 | -44.4 | -44.9 | 15 | | -42.3 | -42.7 | -44.1 | -45 | -46 | -46 | 18 | | -44.3 | -44.3 | -45.6 | -45 | -45 | -46 |
Perhaps the window is a little more narrow with distance with the steel pole piece, the "flat" response width doesn't seem as prevalent at 6mm and 9mm heights as it did with AlNiCo, but due to the margin for error, it's tough to conclude that for certain. It can be see that at -19.3dBm at the closes distance, the voltage output is a lot higher than with the AlNiCo poles. Here's a pic: And here we have 5 neodymium tabs. The gauss reads around 800G at the other end: steel w/ 5 neo | offset mm | 0 | 3 | 6 | 9 | 12 | 15 | height mm | | | | | | | | 3 | | -15.5 | -17.1 | -23.4 | -36.6 | -41.7 | -44.1 | 6 | | -23.9 | -24.3 | -27.4 | -36 | -41 | -45.7 | 9 | | -29.6 | -30.1 | -32.2 | -38 | -41.4 | -44 | 12 | | -36.9 | -36.7 | -38.3 | -40.7 | -43.5 | -44.3 | 15 | | -41.7 | -41.5 | -42.4 | -43.2 | -45.5 | -45.4 | 18 | | -44.4 | -44.1 | -45 | -44.2 | -46.5 | -47 |
With -15.5dBm at the closest distance, the 5 tabs definitely bumps up the voltage output even more. Once again, there doesn't appear to be such "flat" windows as there was with the AlNiCo. For example, at 9mm distance, with this steel pole piece, the dBm drops from -29.6 to -30.1 to -32.2, losing 2.6dBm, where as the AlNiCo pole at 9mm distance drops with offset from -41.3 to -42 to -42.5, losing only 1.2dB over the same distance. This is a rather faint effect among very bouncy numbers, so I wouldn't conclude much yet, but say there's something more to look at there. Theory: we know the permeable steel increases the overall output, in accordance with basic transformer core theory, but maybe the steel pole piece disproportionately "rewards" the segment of string that is closest to itself, while the less permeable AlNiCo is relatively "indifferent", or non-interactive, with the segment of string that it is closest to, making for a "wider window". I measured a few of my guitars and found that I generally have my neck pickups about 4 to 5mm from the strings, and the bridge about 3mm from the strings. At those distances, all the testing shows an effective aperture that's as narrow as the pole piece.
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Post by antigua on Mar 19, 2017 0:07:21 GMT -5
You run these flawed experiments and then sprint to the nearest pickup forums to blast your newfound knowledge as if it's canon. ... The FACT is, I work with pickup technology where I can literally touch a button during the R&D process and toggle <1dB at 10kHz and everyone in the room hears the difference It sounds like what you want to have happen, is you want your input regarded, without the same scrutiny that must be applied to any other input, whether it be from some blog, or an at-home test I, or someone else performs. You ask for this exemption on the basis that you are bound by an NDA. Sadly, your NDA effectively mutes your input, because it precludes the same scrutiny that must be applied to all input, in order for it to be regarded. Your NDA probably doesn't prevent you from demonstrating these same concepts with your own at-home tests. I wouldn't be asking you to put forth any effort I haven't put forth myself if I asked you to conducts such tests and share the results. It would make a lot of sense to host your findings on a blog, as Ken Willmott and Scott Lawing have done. The main reason I haven't created a blog myself is that I consider myself an amateur, and I can make good use the feedback these forum posts bring, as well as the informality of it all. Regardless of how I feel about the content of your claims, you certainly qualify to operate a blog on account of your being professionally involved with the industry.
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Post by stratotarts on Mar 19, 2017 15:18:04 GMT -5
I think it makes sense that the sensing area is smaller for steel poles vs. alnico. The fact that the permeability is much greater means that the field will tend to concentrate more towards the center of the pole. More puzzling is the result that that staggered pole resulted in a wider field. That is strange.
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Post by Charlie Honkmeister on Mar 19, 2017 19:13:49 GMT -5
I'll do what I always do, which is to share anecdotally but I can't give a 360° tour of a multi-year R&D project funded by companies who have earned the right to do so over decades of discovery and fair commerce. (I'm not suggesting that's what YOU are asking, just that it's a common theme) To answer the question directly, Fluence is the most obvious project, in that one thing I've mentioned publicly in the past (without revealing final iteration data) is that the original Fluence core had a resonant peak of 80kHz. I have the full spectrum at my fingertips during the voicing process. I can literally listen to the difference 1dB at 10kHz makes in realtime. Same is true of 16k, et al. Now, if you run a simple plot of a Fluence vintage Strat voice against a 54 Strat pickup they'll be pretty similar. Whether or not subtle differences are meaningful, or whether someone thinks they're not worth spending money is up to the consumer. But they're not imagined or conjured. As far as Zephyrs were concerned, we felt the subtle differences did manifest themselves north of the resonant peak, and in the time alignment/group delay. They will also not provide any chart or plot that verifies it and I do not work for them anymore. What do you mean when you say a core has a resonant peak of 80KHz? Mike, I understood what Frank meant. The Fluence is a multi-layered PCB coil with printed conductors, and is a low impedance pickup. Given the 80 KHz self-resonant frequency, the Fluence core pickup coil assembly (regardless of hum cancellation technique used) probably is roughly on the order of 20-25 mH and has a very low stray capacitance of about 60-90 pF. This means an overall system preamp gain of about 32 dB or so is needed for adequate output level. I've wound and experimented with conventional low Z pickups in very close to this range so have a ballpark idea of the numbers involved in the Fluence. Obviously Frank is under NDA , so I'm sure he couldn't comment. But it is certainly true that having a self-resonance like that, well above the audio range, allows a dead flat audio frequency (and well above) response, which can be voiced by EQ on the preamp board any way you please, given a good enough S/N ratio in the preamp. But AFAIK all the Fluence products only have two pre-selected voicings and you can't physically access a point which is just preamped and doesn't have the EQ applied. But during R&D they had the whole thing breadboarded instead of one epoxied unit, and could play with any EQ they wanted. There's actually a reason I asked Frank about the "over 5Khz" response. I'm still on the fence about whether anything over flat response to 8 Khz to 10 Khz is necessary for a magnetic guitar pickup. I'm intrigued by Frank's statements that it does matter and is audible. Currently I'm in the medium Z design space without preamping, and with about a 10-12 KHz self-resonance, at the expense of only about 6 dB of reduced output. It wouldn't be very hard to go lower on inductance, preamp about 12 dB or so, and get flat response to 22 or even 25KHz. So regardless of what Frank can or can't disclose, or what we can actually test in those products, it's still possible for someone to explore this question in detail.
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Post by stratotarts on Mar 19, 2017 20:28:47 GMT -5
There are many simple ways of constructing a higher frequency pickup system. The simplest is to use the parallel configuration of a humbucker. Actually, you could use a high impedance preamp with a suitably chosen resistive load, and get an almost flat response up to the unloaded resonant peak of most existing pickups. That would get you up to 10k without breaking a sweat. A low impedance, low inductance coil can also get you there. But when you look at sonic preferences, most players dislike the tone of high fidelity (high frequency) pickups. For example, everyone raves about the Cavalier Lion. Well the frequency response is one of the lowest of any Tele bridge out there.
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Post by Charlie Honkmeister on Mar 19, 2017 21:01:06 GMT -5
There are many simple ways of constructing a higher frequency pickup system. The simplest is to use the parallel configuration of a humbucker. Actually, you could use a high impedance preamp with a suitably chosen resistive load, and get an almost flat response up to the unloaded resonant peak of most existing pickups. That would get you up to 10k without breaking a sweat. A low impedance, low inductance coil can also get you there. But when you look at sonic preferences, most players dislike the tone of high fidelity (high frequency) pickups. For example, everyone raves about the Cavalier Lion. Well the frequency response is one of the lowest of any Tele bridge out there. Yep, absolutely agree with this and that is the approach I'm playing with now. A 4 Henry humbucker in series coil mode becomes a 1 Henry humbucker in parallel coil mode, with a self-resonance over 10K depending on stray and cable capacitance. Four-wire "vintage PAF" sets such as the SD Pearly Gates are right in the strike zone. So are quite a few single-coil sized rail humbuckers. Combine that with onboard variable load capacitance and reasonable resistive loading, into a high impedance buffer, and you get amazing tonal versatility with a twist of a pot.
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Post by antigua on Mar 19, 2017 21:48:36 GMT -5
There are many simple ways of constructing a higher frequency pickup system. The simplest is to use the parallel configuration of a humbucker. Actually, you could use a high impedance preamp with a suitably chosen resistive load, and get an almost flat response up to the unloaded resonant peak of most existing pickups. That would get you up to 10k without breaking a sweat. A low impedance, low inductance coil can also get you there. But when you look at sonic preferences, most players dislike the tone of high fidelity (high frequency) pickups. For example, everyone raves about the Cavalier Lion. Well the frequency response is one of the lowest of any Tele bridge out there. Speaking of love for low resonant peaks; a P-90, 7 henries inductance, 2.0kHz loaded resonant peak. It goes to show that a pickup with a highly attenuated treble can still get good reviews as a clean pickup. There are many simple ways of constructing a higher frequency pickup system. The simplest is to use the parallel configuration of a humbucker. Actually, you could use a high impedance preamp with a suitably chosen resistive load, and get an almost flat response up to the unloaded resonant peak of most existing pickups. That would get you up to 10k without breaking a sweat. A low impedance, low inductance coil can also get you there. But when you look at sonic preferences, most players dislike the tone of high fidelity (high frequency) pickups. For example, everyone raves about the Cavalier Lion. Well the frequency response is one of the lowest of any Tele bridge out there. Yep, absolutely agree with this and that is the approach I'm playing with now. A 4 Henry humbucker in series coil mode becomes a 1 Henry humbucker in parallel coil mode, with a self-resonance over 10K depending on stray and cable capacitance. Four-wire "vintage PAF" sets such as the SD Pearly Gates are right in the strike zone. So are quite a few single-coil sized rail humbuckers. Combine that with onboard variable load capacitance and reasonable resistive loading, into a high impedance buffer, and you get amazing tonal versatility with a twist of a pot. It can be challenging to get a high resonance with parallel PAFs because the capacitance combines in parallel, but a split Filter'tron might do the trick. The modern make Gretsch HiLoTron can reach way up there if you have a low capacitance cable: Here's a point to consider, this plot I posted from Celestion's site showed a drop off at 5kHz, but there is content there above 5kHz, it's merely much less than than below 5kHz. With applied gain, the clipping produces harmonics that exceed 5kHz, and you see activity pick up beyond 5kHz, but it's still attenuated relative to everything below 5kHz. Here is a clean Tele into an Orange amp: Here's the same rig with the gain maxed out: With respect to the subject of this thread, note that these harmonics are a product of clipping, and not linearly transferred from the guitar pickup. So it seems that it's not a matter of all or nothing past 5kHz, it's about getting a pleasing proportion. I know they make special amplifiers for acoustic guitars; isn't the idea there to have a flatter frequency response beyond 5kHz?
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Post by ms on Mar 19, 2017 23:14:12 GMT -5
There are many simple ways of constructing a higher frequency pickup system. The simplest is to use the parallel configuration of a humbucker. Actually, you could use a high impedance preamp with a suitably chosen resistive load, and get an almost flat response up to the unloaded resonant peak of most existing pickups. That would get you up to 10k without breaking a sweat. A low impedance, low inductance coil can also get you there. But when you look at sonic preferences, most players dislike the tone of high fidelity (high frequency) pickups. For example, everyone raves about the Cavalier Lion. Well the frequency response is one of the lowest of any Tele bridge out there. Exactly. And of course more than one pickup is sold by using the "vintage" word, but then you wind more wire on than the original pickup so it sounds better with distortion.
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Post by JohnH on Mar 20, 2017 2:07:53 GMT -5
My view is that response of magnetic pickups is relevant up to around 10khz, and I lose interest after that. The cases where it becomes so are particularly in guitars with active wiring where the effect of cable capacitance becomes negated. I have three guitars like this plus a cable with a preamp in the jack tip for use with others. I do prefer my better guitars without this though, unless i need to feed into a mixer.
Anyway, with normal pickups, actuve buffer and a guitar amp/cab, i can definately hear the slight extra edge when the buffer allows those higher frequencies above 5khz to come through, even with a 12" guitar speaker.
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frankfalbo
Meter Reader 1st Class
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Post by frankfalbo on Mar 20, 2017 4:15:06 GMT -5
Theory: we know the permeable steel increases the overall output, in accordance with basic transformer core theory, but maybe the steel pole piece disproportionately "rewards" the segment of string that is closest to itself, while the less permeable AlNiCo is relatively "indifferent", or non-interactive, with the segment of string that it is closest to, making for a "wider window". But are you starting to see how a neighboring pole piece might have an effect on either or both of these theories? You've already surprised yourself a couple times here. And please don't discount that the extra neos have also altered the shape of your field both above and below the coil (or is it below and above since you're on top of the strings?) No, I'm not looking for validation if that's what you're implying. I'm looking to stop the spread of false and/or misleading information. If I see something out there like, "a difference of 1dB at 8kHz is inaudible" or when you've said "Humans can't reliably detect differences of 1dB or less" it's false within the parameters of what we're dealing with, because 1dB does not equal 1dB out the speaker. If you won't listen to my experiences then I'll just have to try to knock down some of these statements on other forums when I come across them. Of COURSE it does. If I duplicate a home-test to prove out something that is a manifestation of knowledge gained from proprietary R&D conducted while employed I most certainly have transgressed an NDA, possibly a non-compete, but most of all, violate trust that people have in me. It would demonstrate a lack of integrity. I need to make a living at this. I don't have a "day job" like some of you. I have a beautiful wife and 4 kids. I'm not going to threaten their well being just to win some internet argument about phase anomalies.
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frankfalbo
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Post by frankfalbo on Mar 20, 2017 4:29:58 GMT -5
What do you mean when you say a core has a resonant peak of 80KHz? Mike, I understood what Frank meant...80 KHz self-resonant frequency... There's actually a reason I asked Frank about the "over 5Khz" response. I'm still on the fence about whether anything over flat response to 8 Khz to 10 Khz is necessary for a magnetic guitar pickup. I'm intrigued by Frank's statements that it does matter and is audible. Currently I'm in the medium Z design space without preamping, and with about a 10-12 KHz self-resonance, at the expense of only about 6 dB of reduced output. Right. And let's be clear I'm not suggesting "flat out to XXK" is pleasing. What I'm referring to, is for example, if within the response curve of say a PAF or Strat, you alter information past 8 or 10K, those deltas ARE meaningful. Re: Medium Z, my latest batch of guitars are solidbodies with P90's, and since Fishman hasn't released a P90 I'm winding my own for them, with 41AWG Cardas wire, with phenomenal results and passive. In a way, it's still R&D for Fluence in that we might use these as one of the benchmarks when we create a P90 someday. I can not say but no, it does not need to be that high. The Fluence cores are much more efficient than a micro-coil or anything you can wind. They don't translate to a wire gauge's behavior at all. There are some characteristics that would be associated with higher gauges and some with lower gauges, but the audio produced from this type of coil stack outperforms anything wire-wound.
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Post by ms on Mar 20, 2017 6:57:33 GMT -5
Mike, I understood what Frank meant...80 KHz self-resonant frequency... There's actually a reason I asked Frank about the "over 5Khz" response. I'm still on the fence about whether anything over flat response to 8 Khz to 10 Khz is necessary for a magnetic guitar pickup. I'm intrigued by Frank's statements that it does matter and is audible. Currently I'm in the medium Z design space without preamping, and with about a 10-12 KHz self-resonance, at the expense of only about 6 dB of reduced output. Right. And let's be clear I'm not suggesting "flat out to XXK" is pleasing. What I'm referring to, is for example, if within the response curve of say a PAF or Strat, you alter information past 8 or 10K, those deltas ARE meaningful. Re: Medium Z, my latest batch of guitars are solidbodies with P90's, and since Fishman hasn't released a P90 I'm winding my own for them, with 41AWG Cardas wire, with phenomenal results and passive. In a way, it's still R&D for Fluence in that we might use these as one of the benchmarks when we create a P90 someday. I can not say but no, it does not need to be that high. The Fluence cores are much more efficient than a micro-coil or anything you can wind. They don't translate to a wire gauge's behavior at all. There are some characteristics that would be associated with higher gauges and some with lower gauges, but the audio produced from this type of coil stack outperforms anything wire-wound. So how could this much higher efficiency be achieved? Higher copper to insulation ratio in the coil? I do not think so. Magnetic cores that better concentrate and amplify the flux from the vibrating string? Again, I do not think so. Effective permeability is limited in short open cores no matter how high the material permeability is, and materials that give both low loss and high permeability allow higher Q coils, but that does not increase the signal level at the lower audio frequencies where most of the guitar energy is. But this is really a non issue. Any reasonable coil with a well designed preamp gives very good signal to noise ratio, and once you have that potted up into one package, it would be a lot of work for anyone to determine the details of how it was done.
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Post by antigua on Mar 20, 2017 9:45:06 GMT -5
But are you starting to see how a neighboring pole piece might have an effect on either or both of these theories? You've already surprised yourself a couple times here. And please don't discount that the extra neos have also altered the shape of your field both above and below the coil (or is it below and above since you're on top of the strings?) This idea "I'm right because I didn't change my mind, and you're wrong because you did" is very sad. This is the kind of lazy, quick judgement that causes a lot of problems in the world we live in. Whether I "see" how the neo "might have an effect" is irrelevant, all that matters is what can be demonstrated. So if you're NDA prevents you from helping demonstrate anything, then we've reached an impasse. No, I'm not looking for validation if that's what you're implying. I'm looking to stop the spread of false and/or misleading information. If I see something out there like, "a difference of 1dB at 8kHz is inaudible" or when you've said "Humans can't reliably detect differences of 1dB or less" it's false within the parameters of what we're dealing with, because 1dB does not equal 1dB out the speaker. If you won't listen to my experiences then I'll just have to try to knock down some of these statements on other forums when I come across them. What matters at the end of the day is what anyone can prove. Hearsay and strong assurances ultimately amount to nothing in fields of science. When future researches come looking for data, they're going to see what I've done and say "his tests were partial and could have been more complete, but he was doing this all for free, documented his process, and it's better than nothing", and they'll say "this Frank guy made lots of claims, but he provided no evidence one way or the other, so it's about as good as nothing". This is exactly what happens when I come across information Bill Lawrence had tendered. It's all very interesting, but there's almost never proof or sourcing, so I just have to leave it there. Most of I what I have leaned concretely has come from studying inductors and transformers in general. I have to leave the field of guitar pickups entirely in order to find good, backed data. Of COURSE it does. If I duplicate a home-test to prove out something that is a manifestation of knowledge gained from proprietary R&D conducted while employed I most certainly have transgressed an NDA, possibly a non-compete, but most of all, violate trust that people have in me. It would demonstrate a lack of integrity. I need to make a living at this. I don't have a "day job" like some of you. I have a beautiful wife and 4 kids. I'm not going to threaten their well being just to win some internet argument about phase anomalies. I'd argue that you're doing your career no favors with this discourse. A future prospective employer might ask if you're working with the larger guitar technology community, or being combative with it. It's usually not a good idea to be perceived as polarizing, that's probably why you don't see a lot of your peers engaging in a similar fashion.
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frankfalbo
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Post by frankfalbo on Mar 20, 2017 10:13:14 GMT -5
MS: I honestly can't tell if you're asking a question or making a declarative statement. Are you asking why it's a more efficient coil? Or declaring that it isn't; that I'm wrong? I was asked how I seem to have some deeper information about what's happening within the coil and I replied that part of it is from Fluence R&D, partly through stack R&D...
You can learn some of this with an old stack design, where the top and bottom coils are equal and the magnet penetrates the coil. Track the coils sepeately, look at them in isolation, overlay them, check time alignment if you have that level of precision available...but if some of the theories presented here were correct, you should be able to increase the amplitude of the bottom coil until the two signals cancel 100%. But they never will. So at the point of the highest cancellation, what is left behind tells part of the story of comb filtering within the coil.
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Post by ms on Mar 20, 2017 11:36:42 GMT -5
MS: I honestly can't tell if you're asking a question or making a declarative statement. Are you asking why it's a more efficient coil? Or declaring that it isn't; that I'm wrong? I was asked how I seem to have some deeper information about what's happening within the coil and I replied that part of it is from Fluence R&D, partly through stack R&D... You can learn some of this with an old stack design, where the top and bottom coils are equal and the magnet penetrates the coil. Track the coils sepeately, look at them in isolation, overlay them, check time alignment if you have that level of precision available...but if some of the theories presented here were correct, you should be able to increase the amplitude of the bottom coil until the two signals cancel 100%. But they never will. So at the point of the highest cancellation, what is left behind tells part of the story of comb filtering within the coil. There is no delay significant on an audio scale in the changes in flux from the vibrating string reaching the lower coil. Of course the amplitude of the changes in flux is lower in the bottom coil. The field can only be partly confined by any pole piece that is part of such a wide open magnetic circuit. Yes, I think you are wrong about the "efficiency" of the fluence coil and various of the other things you have written in this discussion.
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Post by antigua on Mar 20, 2017 11:37:19 GMT -5
We can see an apparent aperture change with distance. This means that, if you think of a pickup as many little pickups stacked together in series, the pickup at the bottom of the stack has a wider aperture than the pickup at the top of the stack: AlNiCo, A string | offset mm | 0 | 3 | 6 | 9 | 12 | 15 | height mm | | | | | | | | 3 | | -24.5 | -27.1 | -38.9 | -47.5 | -46.7 | -46.8 | 6 | | -38.4 | -38.9 | -41.8 | -44.3 | -48.8 | -49.7 | 9 | | -42.4 | -40.6 | -40.7 | -48.1 | -49.5 | -49.8 | 12 | | -44.7 | -44.3 | -45.1 | -45.3 | -45.6 | -45.8 | 15 | | -44.7 | -45 | -45.1 | -45.5 | -45.6 | -49.8 |
A Strat coil is about 12mm tall. At the top of the stack, the aperture is sharp like a pencil, but at the bottom, it's nearly flat like the eraser end. The peak dBm was -24.5 at the top, and -44.7 at the bottom, a 20dB drop to the bottom of the coil, with more than 50% of this loss occurring between 3mm and 6mm. Therefore, any signal generated at the lower end of the stack that is in conflict with the top half of the stack will have an imbalance in power that heavily favors the top of the stack. If there were an agent of cancellation, you still won't get perfect cancellation of any sort, and that's fortuitous, because it's the basis on which stacked humbuckers operate. As for comb filtering, this is a specific type of cancellation that requires two conditions 1) that you have two like signals that are equal, or nearly equal, in amplitude, or else one is not strong enough to cause significant cancellation of the other, and 2) they need to be out of phase to some degree. The greater the degree, the more filtering that occurs. With guitar strings, the comb filtering comes from the fact that the same harmonic displacement occurs in multiple locations along the string, each is 180 degrees out of phase with its neighbor. With multiple microphones, the speed of sound is the causes a delay that causes two near identical signals to be out of phase. To entertain the notion of some kind of inner-coil comb filtering, there needs to be some mechanism that causes a delay, or the presentation of two identical, but out of phase, signals. It's not apparent to me what would give rise to this, and why it wouldn't present a problem with any electrical transformer, in any application.
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frankfalbo
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Post by frankfalbo on Mar 20, 2017 11:54:44 GMT -5
Jeeeez I try to give you some encouragement and your response is personal attack? You're looking for a fight that doesn't exist. As for being polarizing or combative, I'm pretty sure your online history in aggregate fits that description. I get along with pretty much everybody, except some people who have the reputation of being polarizing. What I mean is, when you stack the neos you change the shape of the field. It's not just the strength increasing. And what you're discovering with the pole further from the coil also changes with neighboring poles being higher, level, or below. And with all due respect, what matters at the end of the day, is putting an instrument in someone's hands that brings them joy, or catharsis, or whatever else the arts provide society. I realize that doesn't fit the format of this sub-group, sorry.
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Post by antigua on Mar 20, 2017 12:08:13 GMT -5
Jeeeez I try to give you some encouragement and your response is personal attack? You're looking for a fight that doesn't exist. As for being polarizing or combative, I'm pretty sure your online history in aggregate fits that description. I get along with pretty much everybody, except some people who have the reputation of being polarizing. What I mean is, when you stack the neos you change the shape of the field. It's not just the strength increasing. And what you're discovering with the pole further from the coil also changes with neighboring poles being higher, level, or below. And with all due respect, what matters at the end of the day, is putting an instrument in someone's hands that brings them joy, or catharsis, or whatever else the arts provide society. I realize that doesn't fit the format of this sub-group, sorry. That was not a personal attack; it was not a statement about you as a person, it was a statement about something you had said, the general nature thereof. What you said in turn is much closer to a personal attack, as it was a broad statement about my character. You didn't provide enough information regarding the field shape and the neodymium for me to think I should doubt my test setup, or somehow change my test setup to improve it's accuracy somehow. Not enough to go on. An utterance doesn't amount to constructive critique. Magnetization drops off inverse cube of the distance, and the steel pole piece placed more than 18mm separation between the neo itself and the string. Furthermore, the neo button has no permeability by itself, which is a bonus.
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frankfalbo
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Post by frankfalbo on Mar 20, 2017 12:09:31 GMT -5
We can see an apparent aperture change with distance. This means that, if you think of a pickup as many little pickups stacked together in series, the pickup at the bottom of the stack has a wider aperture than the pickup at the top of the stack: A Strat coil is about 12mm tall. At the top of the stack, the aperture is sharp like a pencil, but at the bottom, it's nearly flat like the eraser end. The peak dBm was -24.5 at the top, and -44.7 at the bottom, a 20dB drop to the bottom of the coil, with more than 50% of this loss occurring between 3mm and 6mm. No...Please can everyone else help me out with this one? Your aperture readings...your display of the string window widening with distance from the top of the pole do not translate into a widening of the string window as seen by the bottom of the coil. The magnet has a return path. The string window is not infinitely widening in aperture further down the pole. Not really. I mean you're right that the degree of amplitude and phase imbalance correlates to the degree of impact, but in your words, no it does not have to be "equal or nearly equal in amplitude" to be strong enough to have an effect. I realize this is a flawed analogy, but if you have those two mics in different positions, all it takes is a tiny bleed of volume for the combing to be audible, not near equal loudness.
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Post by antigua on Mar 20, 2017 12:21:59 GMT -5
No...Please can everyone else help me out with this one? Your aperture readings...your display of the string window widening with distance from the top of the pole do not translate into a widening of the string window as seen by the bottom of the coil. The magnet has a return path. The string window is not infinitely widening in aperture further down the pole. That's an OK point, when the pickup is far from the string, there is no pole piece guiding the flux down to the imagined "lower end of the coil" / actual top of coil. We know that steel poles guide flux much more effectively than AlNiCo poles, so this inaccuracy mostly only applies to steel pole pickups, and then only Stratocaster types, since PAF and P-90 coils are much more shallow. The effect of the steel pole piece would be to carry more flux to the lower portion of the coil, also narrow the aperture at the bottom, making the aperture through the coil more homogeneous overall. That's corroborated by the test a page back, that showed a more narrow aperture with the steel pole, as well as a test in another thread that showed increased output with steel pole pieces in place of AlNiCo. In summary, I don't see that there is anything of great consequence here. The situation seems to be understood and under control. Not really. I mean you're right that the degree of amplitude and phase imbalance correlates to the degree of impact, but in your words, no it does not have to be "equal or nearly equal in amplitude" to be strong enough to have an effect. I realize this is a flawed analogy, but if you have those two mics in different positions, all it takes is a tiny bleed of volume for the combing to be audible, not near equal loudness. Again, regardless of amplitude, what is the agent of phase variance, what would cause it? I'll try using my imagination here, let's suppose we're using a Strat pickup with AlNiCo poles, so we have reason to believe there's an 18mm overall aperture at the lowest depth of the coil, and that some comb filtering occurs with this wider aperture that doesn't occur near the top. Again, the amount of string-based comb filtering with 18mm width is in the high frequency range, and would minimal in amplitude due to the great distance between that depth of the coil and the guitar string. That's the best I can come up with, and it seems very unlikely to impose an audible effect.
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frankfalbo
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Post by frankfalbo on Mar 20, 2017 13:07:11 GMT -5
If you want to get into the HiFi voodoo jargon that you probably won't like, one phenomenon is referred to as group delay. Highs/mids/lows out of time alignment with one another, in a smear. Proprietary testing methods notwithstanding, it's easier for me to show the effects manifested than it is to show it on screen. This is where on other forums you've heard me talk about all the notes in a complex chord to be able to survive heavy gain; that it is not as much frequency dependent as it is time alignment.
But really it's quite simple to see a part of it on a macro level by recording both coils from an equally wound stack, and playing around with the amplitude, looking for time alignment anomalies...And it's not necessary for you to concede to any time-based causality in a wire-wound coil, traversing closer to, and further from the string, even though I'm saying there is something there. You can just attribute it to out of phase flux disturbance of you like. The result is the same.
You can even start cutting it up into different frequency bands with band pass filters and looking at sections against one another.
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