|
Post by JohnH on Jul 20, 2017 15:29:40 GMT -5
Yes of course - definitely. Actually my best split humbucker is at the bridge on my HSS Strat, which measures 4.5H and split it measures 2.2H. I split to the slug coil, which is nearest the neck. Tonally, its sits very well with the two 2.4H Tx Sp singles, and the loudness balances O too, since its set higher than they are. But its interesting that the single tone has more bright edge to it than does the parallel wired HB, for which inductance is about 1.4H as measured.
|
|
|
Post by antigua on Jul 20, 2017 16:25:27 GMT -5
All my testing shows that the intrinsic capacitance in parallel causes the resonant peaks to be nearly equal, parallel versus split. They're not identical, but surprisingly close. Therefore, the difference between split and parallel, aside from humbucking, is mostly defined by that harmonic difference, and so it's interesting that you say you don't observe much difference when splitting from slug to screw, because it seems the combination of the two does amount to a greater difference. It might be the comb filtering that is to blame. The mystery to me is why the attack sounds difference between parallel and split. It's hard to describe, but I think it's easy to hear. The split coil attack is more dry and linear, the parallel (or series) wiring has a scooped, chiming bell like attack, as a result of both coils operating at once, regardless series/parallel. If you have a way to test this, give it a shot and tell me if you agree. I'm interesting in narrowing down the cause of that difference.
|
|
|
Post by JohnH on Jul 20, 2017 17:06:22 GMT -5
Ill try to post some samples over the weekend. Ill do them DI'ed via a buffer, so no amp involved.
i think if there are slug and screw coils then that does cause a difference. Its where there are two slugs or two screws that you can then hear if position makes much difference, and i think it does at the bridge but not much at the neck.
|
|
|
Post by ms on Jul 20, 2017 19:05:21 GMT -5
All my testing shows that the intrinsic capacitance in parallel causes the resonant peaks to be nearly equal, parallel versus split. They're not identical, but surprisingly close. Therefore, the difference between split and parallel, aside from humbucking, is mostly defined by that harmonic difference, and so it's interesting that you say you don't observe much difference when splitting from slug to screw, because it seems the combination of the two does amount to a greater difference. It might be the comb filtering that is to blame. The mystery to me is why the attack sounds difference between parallel and split. It's hard to describe, but I think it's easy to hear. The split coil attack is more dry and linear, the parallel (or series) wiring has a scooped, chiming bell like attack, as a result of both coils operating at once, regardless series/parallel. If you have a way to test this, give it a shot and tell me if you agree. I'm interesting in narrowing down the cause of that difference. Two coils literally are scooped, as the "Tillman" calculation with two coils spaced by .7whatever with an aperture of about .2 shows. What you hear is exactly what you see. guitarnuts2.proboards.com/post/81799
|
|
|
Post by ashcatlt on Jul 21, 2017 12:02:56 GMT -5
I don't think that we can take the audio output of a pickup in a given position and use filters to actually move the pickup. That requires more information than we have (specifically what fret on what string at any given instant), and really needs resynthesis to do well.
It IS though pretty easy to come close to swapping out pickups in the one position. Your method of matching filters works to the level of precision your tools and patience allow. I think convolution would probably be faster and closer, though. This is the way that good mic modeling software works.
The hardest part is generating a good impulse at the pickup. A screwdriver tap might work, but its probably not consistent enough. I had thought maybe some sort of solenoid device, but I think that will make an EM pulse on top of the physical motion, and I think skews the results. Some contaption using rubber bands, maybe???
So once you've got an impulse from your source pickup, and one from your destination pickup, I think you just deconvolve the two and use the resulting IR in whichever convolution plugin you prefer and it just works. I think.
Edit - Forgive me if this has been covered. I didn't actually read the whole thread because it quickly veers off into several different unrelated topics. I meant to post this at the beginning, but...excuses...
|
|
|
Post by wgen on Jul 23, 2017 12:34:03 GMT -5
Tillman's figure 13 for a humbucker with an assumed 2.5 inch aperture shows sows significant loss by 2 KHz on the low E string. Of course, it is not right since the aperture is wrong. The actual response would be obtained by using a pole width aperture on each of two closely spaced coils. Here is what I predict for the hum bucker harmonic response (that is, the part due to coil location and aperture), two coils spaced by 11/16", each with an aperture the width of a pole piece. Of course, this is just one factor. I would expect most of the harmonic roll off to be the result of string stiffness (resistance to bending) View AttachmentMay I ask you if you could elaborate this some more? I've been experimenting a lot with string gauges lately, and I have many difficulties understanding what is really happening to the tone with changes. Could you please explain this subject to me, from a more "visual" point of view, perhaps? Thank you very much in advance!
|
|
|
Post by ms on Jul 23, 2017 13:14:21 GMT -5
Here is what I predict for the hum bucker harmonic response (that is, the part due to coil location and aperture), two coils spaced by 11/16", each with an aperture the width of a pole piece. Of course, this is just one factor. I would expect most of the harmonic roll off to be the result of string stiffness (resistance to bending) May I ask you if you could elaborate this some more? I've been experimenting a lot with string gauges lately, and I have many difficulties understanding what is really happening to the tone with changes. Could you please explain this subject to me, from a more "visual" point of view, perhaps? Thank you very much in advance! I doubt that I can improve on Tillman's very fine explanation. Have you read this carefully:www.till.com/articles/PickupResponse/ ?
|
|
Deleted
Deleted Member
Posts: 0
Likes:
|
Post by Deleted on Jul 23, 2017 14:52:24 GMT -5
Hey Antigua, It's a synth designed mostly to produce non-guitar tones, that's why they don't offer COSM, and you bring a fantastic point here. Maybe *that's* the reason why they were unable to provide the ultimate tool for guitarists (persuading synth + COSM modelling with the *stock* pups).
|
|
|
Post by wgen on Jul 23, 2017 16:48:00 GMT -5
May I ask you if you could elaborate this some more? I've been experimenting a lot with string gauges lately, and I have many difficulties understanding what is really happening to the tone with changes. Could you please explain this subject to me, from a more "visual" point of view, perhaps? Thank you very much in advance! I doubt that I can improve on Tillman's very fine explanation. Have you read this carefully:www.till.com/articles/PickupResponse/ ? Thanks for the reply, and sorry for my previous post, I think I didn't wrote it correctly... What I don't really understand is specifically the effect of string changes, what string stiffness do to the tone...I didn't find these strictly related informations in the Tillman article, or maybe I didn't understand everything. In your previous post you talked about different strings having an effect to the tone...you mentioned resistance to bending specifically. So I was asking if you could explain this, if a more "visual" explanation is possible, for example. Thank you again!
|
|
|
Post by antigua on Jul 24, 2017 0:37:50 GMT -5
All my testing shows that the intrinsic capacitance in parallel causes the resonant peaks to be nearly equal, parallel versus split. They're not identical, but surprisingly close. Therefore, the difference between split and parallel, aside from humbucking, is mostly defined by that harmonic difference, and so it's interesting that you say you don't observe much difference when splitting from slug to screw, because it seems the combination of the two does amount to a greater difference. It might be the comb filtering that is to blame. The mystery to me is why the attack sounds difference between parallel and split. It's hard to describe, but I think it's easy to hear. The split coil attack is more dry and linear, the parallel (or series) wiring has a scooped, chiming bell like attack, as a result of both coils operating at once, regardless series/parallel. If you have a way to test this, give it a shot and tell me if you agree. I'm interesting in narrowing down the cause of that difference. Two coils literally are scooped, as the "Tillman" calculation with two coils spaced by .7whatever with an aperture of about .2 shows. What you hear is exactly what you see. guitarnuts2.proboards.com/post/81799It's something different than that. The "scooping" Tillman describes, and the harmonics values I see differ, are all in the higher frequencies, around 2.5kHz and beyond. The type of tonal effect I'm describing sounds more like a sub 1kHz type of scooping. I just did a steady vibration test with split versus parallel. The previous test I did was manual strumming. The steady state vibration actually supplies far less information overall, because strumming excites a deluge of higher harmonics, where as the steady state only produces the first four or five harmonics, which cap out around 500Hz. Long story short, within those first 4 or 5 harmonics, there is essentially no difference. I wedged a needle between adjacent strings that lightly touches the test string (open G) to tease out harmonics, and doing that rendered measurable harmonic content up to 1.5kHz. Even with those added harmonics, there's not much of a difference to be seen. I noticed harmonic variance in the strumming tests above 2.5kHz, so maybe had the needle induced harmonics that high, I might have seen it happen here too. IOW, I think the steady state harmonics are so low in frequency, that the Tillman comb filtering doesn't even apply in this case. Here is a shot without the needle. The only interesting thin here is that you can see the steady vibration only produces harmonics up to about 300Hz. The sample in the middle is series, and the the left and right side are split to screw and slug. You can see that the split mode shows the exciter coil inducing voltage at 98Hz, and that in parallel more, that 98Hz line is gone.. because it's cancelled out by the humbucking. So I captured just the exciter by itself, without any string movement, made a noise profile out of it, and then negated the noise profile of the exciter coil for subsequent testing. Here's what the DAW looks like, this time with the noise reduction removing the 98Hz exciter noise, and with a needle inducing harmonics. The first section is parallel mode, the second section is split to the coil closer to the bridge, and the third part is the exciter coil noise alone. You can see that the needle causing harmonics causes a distinct oscillation, and that the harmonic parts extend up to 1.5kHz, then essentially "go black": I'm partly not surprised by this result, because I felt the difference in sound was only apparent in the attack period, and that the decay periods didn't sound much different. The harmonic spectral analysis of those attacks didn't look obviously different, either though. It's pretty strange, because supposing there is a difference in the tonality of the two, and that I'm not just imagining it, it's a pretty well hidden difference. Even though this doesn't help explain why parallel and split have a different tone, I think it's interesting that the steady state vibration of the open G doesn't produce harmonics much about 500Hz. That's way below the resonant peak of most pickups on the market. Strumming with a pick, on the other hand, induces harmonics that reach up beyond 6kHz, assuming the pickup allows for it. This means that the difference in resonant peak between two pickups might only manifest when strumming, but disappear in the decay. So, someone asks, "what's the difference between a CS 69 and a Texas Special?", and the logical answer is "the CS 69 is brighter", but what if it's only brighter for a fraction of a second? Then it's not so much a "brighter" pickups in general, it's only brighter in and around the transient, and that might justify a different adjective, like "glassy attack" might make more sense than "brighter". Here's a specrtograph of the full strum, with the guitar pickup wired directly to the mic in, so the resonant peak is rather high, apparently around 6.8kHz: You can see that there's a burst of harmonic amplitude right in the beginning, but it's gone in less than a second, and with a couple seconds is below 2.5kHz, which is about the minimum peak frequency for guitar pickups, and a bit lower than than for P-90s and high output humbuckers. Therefore, there comes a point, rather quickly, where all guitar pickups sound the same, unless there is some dramatic comb filtering at play, such as the case when you have two pickups activated at the same time.
|
|
|
Post by ms on Jul 24, 2017 9:12:44 GMT -5
I think you would be surprised how much high frequencies a guitar string makes. I have a discussion of this at music electronics, guitar:amplifiers:theory and design which I will restart here where further development is more appropriate.
|
|
|
Post by ms on Jul 24, 2017 9:29:28 GMT -5
I doubt that I can improve on Tillman's very fine explanation. Have you read this carefully:www.till.com/articles/PickupResponse/ ? Thanks for the reply, and sorry for my previous post, I think I didn't wrote it correctly... What I don't really understand is specifically the effect of string changes, what string stiffness do to the tone...I didn't find these strictly related informations in the Tillman article, or maybe I didn't understand everything. In your previous post you talked about different strings having an effect to the tone...you mentioned resistance to bending specifically. So I was asking if you could explain this, if a more "visual" explanation is possible, for example. Thank you again! Let's make a mental model of a guitar string. It needs springs (assume perfect little springs) because it can be stretched and it returns the energy stored in the stretching process. But since the string needs to change shape, it needs to bend. So let's hook lots of little springs together end on end and connect them with tiny ball joints that allow frictionless bending in any direction. This would behave very much like a real string except that it is lossless and will keep going forever. So introduce some loss into the ball joints. There is a sort of analogy between this and your cars suspension. It has springs that store energy when compressed or stretched and give it back. It also has shock absorbers, which resists motion; they soak up energy and turn it into heat. So let's let these little ball joints be equipped with an energy loss mechanism which makes them resist bending. Now as the string vibrates, energy is absorbed (and turned into tiny amount of heat) and the vibration amplitude decreases with time. So how does the decrease in vibration amplitude depend on the harmonic number? Higher harmonics have more peaks and nulls along the string. So, for the same amplitude of vibration, more bending is required. For example, the ball joints between the nulls and the peak displacements have to bend to greater angles for a high harmonic than for the fundamental with the same peak amplitude of string displacement. Edit: Also the higher the harmonic number, the higher its frequency, and so the bending one way and then the other takes place more frequently. We expect the vibration time to decrease gradually with increasing harmonic number. This analogy is a bit crude, but it is just intended to give an idea of how it works. Doe this help?
|
|
|
Post by antigua on Jul 24, 2017 11:50:01 GMT -5
I think you would be surprised how much high frequencies a guitar string makes. I have a discussion of this at music electronics, guitar:amplifiers:theory and design which I will restart here where further development is more appropriate. I'm not too surprised, as the spectrograph shows, the harmonic content extends right up to the resonant peak of that test humbucker at just under 7kHz. I bet if I tried this with that Chinese single coil that had a peak beyond 11kHz I might see content way up there. The point I'm getting at is that it only produces those harmonics for a short amount out time, as can be seen above, because they are lost to friction so rapidly, as you mentioned, so pickup variances, within a certain range, becomes less about overall frequency response, and more about just the attack and initial decay. For example, a PAF and a Filter'tron have resonant peaks that are rather far apart. 2.5kHz for the PAF and 4.5kHz for the Filter'tron. That's such a big differences that the Filter'tron might sound noticeably brighter than PAF for a couple seconds, long enough to really notice. But if you have a second PAF that is 3.0kHz, 500Hz above the first PAF, or a second 5.0kHz Filter'tron, one that is 500Hz higher than the first, the decay won't sound as different as the attack. 500Hz of extended response during the attack will be more profound than 500Hz extended response in the decay, and so the adjective that best describes the differences might be in relation to the attack. Often times guitarists talk about "touch sensitivity", and we know those adjectives are inaccurate in a pure physics sense, but to the extent they're saying the difference is mostly observed when they first pluck the strings, they're observation is somewhat accurate, too. Something that has been apparent about pickups for a while now; that when you have a subtle 6dB/oct roll off, you merely get a gradual change in the high end, but when the drop is a more aggressive 12dB/oct, the more thorough omission of higher harmonics changes the character of the guitar tone. Guitarists think of pickups as being more complicated and sophisticated than they really are, and assume the winders are responsible for imbuing them with that sophistication, but I think what's really going on is that they underestimate the colorizing influence of the -12dB/oct roll off. I can try taking that strum sample above, and try simulating lower peaks in order to see how it effects the perception of tone.
|
|
|
Post by wgen on Jul 24, 2017 13:00:00 GMT -5
Thanks for the reply, and sorry for my previous post, I think I didn't wrote it correctly... What I don't really understand is specifically the effect of string changes, what string stiffness do to the tone...I didn't find these strictly related informations in the Tillman article, or maybe I didn't understand everything. In your previous post you talked about different strings having an effect to the tone...you mentioned resistance to bending specifically. So I was asking if you could explain this, if a more "visual" explanation is possible, for example. Thank you again! Let's make a mental model of a guitar string. It needs springs (assume perfect little springs) because it can be stretched and it returns the energy stored in the stretching process. But since the string needs to change shape, it needs to bend. So let's hook lots of little springs together end on end and connect them with tiny ball joints that allow frictionless bending in any direction. This would behave very much like a real string except that it is lossless and will keep going forever. So introduce some loss into the ball joints. There is a sort of analogy between this and your cars suspension. It has springs that store energy when compressed or stretched and give it back. It also has shock absorbers, which resists motion; they soak up energy and turn it into heat. So let's let these little ball joints be equipped with an energy loss mechanism which makes them resist bending. Now as the string vibrates, energy is absorbed (and turned into tiny amount of heat) and the vibration amplitude decreases with time. So how does the decrease in vibration amplitude depend on the harmonic number? Higher harmonics have more peaks and nulls along the string. So, for the same amplitude of vibration, more bending is required. For example, the ball joints between the nulls and the peak displacements have to bend to greater angles for a high harmonic than for the fundamental with the same peak amplitude of string displacement. Edit: Also the higher the harmonic number, the higher its frequency, and so the bending one way and then the other takes place more frequently. We expect the vibration time to decrease gradually with increasing harmonic number. This analogy is a bit crude, but it is just intended to give an idea of how it works. Doe this help? Yes, many thanks. I read this many times, I also re-viewed some drawings of harmonics and fundamentals across the strings, now I think that the bending of the string and the harmonics are closely related just like you said..so that I understand that the stiffness, and the resistance to bending, makes for less higher harmonics than when you have a light gauge, flexible string. Also it should be noted that just like Antigua said, the higher harmonics, those which are closer to the resonant peak of the pickups, have their focus just for a fraction of a second and then the sustain is mostly mids and lower mids. I seem to remember from some music theory that lower frequencies are slower while higher frequencies are faster, and this analysis of the harmonics sampling seems to show just that: an initial focus of treble, then the well known bigger energy required from the lower frequencies "sucks some life out" of the highest harmonics soon after that. Thank you again, you guys are great.
|
|
|
Post by antigua on Jul 24, 2017 13:35:48 GMT -5
Here's a fun fact: flat wound guitar strings sound darker, because the tightly locked, flat surface induces higher friction losses than the relatively slinky shape of much more common round wound strings. And there's an easy way to visualize this; which bracelet will bend more eaily: these round beads, or these flat ones?
|
|
|
Post by wgen on Jul 24, 2017 14:02:03 GMT -5
Here's a fun fact: flat wound guitar strings sound darker, because the tightly locked, flat surface induces higher friction losses than the relatively slinky shape of much more common round wound strings. And there's an easy way to visualize this; which bracelet will bend more eaily: these round beads, or these flat ones? I'd bet the bracelet with the round beads..! Also, I have to add that I love flatwound strings... especially to balance bright sounding instrument pickups
|
|
|
Post by JohnH on Jul 24, 2017 17:15:17 GMT -5
Here's a few related things that I keep in mind:
A perfect string has mass and tension. Those two values together with its length, are all that is needed to derive its fundamental frequency to a very close accuracy.
Balanced sets of guitar strings are designed to have a mass so that roughly the same tension is required to tune them all to their standard pitches. Not exact, but usually within 20% or so. For working the maths, I assume all are equal.
When considering amplitudes, it depends how hard we pluck. What is a standard pluck? is it a consistent deflection of the string before release? or a standard sideways force before release? I assume the latter, as if it is determined by a certain flexing of a pick before the string slips off the tip.
With a given plucking force, a higher-fretted string of a given tension will deflect sideways a proportionally lesser distance before release. This directly relates to the resulting amplitude of vibration in mm.
piezo vs magnetic:
Piezos are sensitive to changes in pressure through the crystal and produce voltage in direct proportion. Plucking the string with a consistent force sideways creates a proportional slight increase and variation in string tension, hence pressure under the bridge and so linear voltage output.
With the mag pickup, it is sensitive to string mass and string velocity which is proportional to amplitude x frequency. But this is balanced by higher harmonics and higher fretted notes having lower amplitudes in inverse proportion to frequency.
So I think that both piezos and magnetic pickups will nominally (before considering electical and pickup dimensio and location effects), give linear and equivalent outputs. Piezo's, consistent variations in string force lead to pressure variations in the piezo lead to signal voltage. Magnetic, frequency dependent increase in velocity is compensated by frequency dependent decrease in vibration amplitude.
The differences in pickup tone is mainly about the RLC resonances and filtering in the mag system plus some'sensing window' effects vs basicly none in a piezo feeding a simple buffer. Also the mag pickup output is affected by its location along the string whereas the piezo is getting all harmonics arriving at the bridge.
Across different strings in a 'perfect' set, the piezo system sees consistent changes in string force with consistent plucks. The magnetic system sees lower frequencies, hence lower string velocity, compensated by greater moving string mass creating flux changes. so both types give a fair balance across strings.
damping and decay
The decay in vibration in most physical systems can be represented by a damping factor, which is high for a car suspension, low for a building structure (re my day job) and very low for a vibrating musical string. One of the ways to express this is in terms of the % of amplitude reduction in each cycle. If such a number is indeed reasonably consistent then it explains why after a given time, the high harmonics which have done many cycles have largely died away, while low harmonics and eventually just the fundamental, ring on. Once there is only the fundamental, all pickups sound the same.
String type and weight
Theres definately a tonal difference with heavier strings being more resistant to being flexed, hence suppressing higher harmonics in favour of lower ones. Its why we need wound strings or else a very thick plain string with enough mass to achieve a low note would resist bending into high harmonics and sound more like a piano. Also, with heavier acoustic strings, a wound G is often used. Wound strings add tbe requured mass without adding bending stiffness.
|
|
|
Post by wgen on Jul 25, 2017 2:35:32 GMT -5
Here's a few related things that I keep in mind: A perfect string has mass and tension. Those two values together with its length, are all that is needed to derive its fundamental frequency to a very close accuracy. Balanced sets of guitar strings are designed to have a mass so that roughly the same tension is required to tune them all to their standard pitches. Not exact, but usually within 20% or so. For working the maths, I assume all are equal. When considering amplitudes, it depends how hard we pluck. What is a standard pluck? is it a consistent deflection of the string before release? or a standard sideways force before release? I assume the latter, as if it is determined by a certain flexing of a pick before the string slips off the tip. With a given plucking force, a higher-fretted string of a given tension will deflect sideways a proportionally lesser distance before release. This directly relates to the resulting amplitude of vibration in mm. piezo vs magnetic: Piezos are sensitive to changes in pressure through the crystal and produce voltage in direct proportion. Plucking the string with a consistent force sideways creates a proportional slight increase and variation in string tension, hence pressure under the bridge and so linear voltage output. With the mag pickup, it is sensitive to string mass and string velocity which is proportional to amplitude x frequency. But this is balanced by higher harmonics and higher fretted notes having lower amplitudes in inverse proportion to frequency. So I think that both piezos and magnetic pickups will nominally (before considering electical and pickup dimensio and location effects), give linear and equivalent outputs. Piezo's, consistent variations in string force lead to pressure variations in the piezo lead to signal voltage. Magnetic, frequency dependent increase in velocity is compensated by frequency dependent decrease in vibration amplitude. The differences in pickup tone is mainly about the RLC resonances and filtering in the mag system plus some'sensing window' effects vs basicly none in a piezo feeding a simple buffer. Also the mag pickup output is affected by its location along the string whereas the piezo is getting all harmonics arriving at the bridge. Across different strings in a 'perfect' set, the piezo system sees consistent changes in string force with consistent plucks. The magnetic system sees lower frequencies, hence lower string velocity, compensated by greater moving string mass creating flux changes. so both types give a fair balance across strings. damping and decay The decay in vibration in most physical systems can be represented by a damping factor, which is high for a car suspension, low for a building structure (re my day job) and very low for a vibrating musical string. One of the ways to express this is in terms of the % of amplitude reduction in each cycle. If such a number is indeed reasonably consistent then it explains why after a given time, the high harmonics which have done many cycles have largely died away, while low harmonics and eventually just the fundamental, ring on. Once there is only the fundamental, all pickups sound the same. String type and weight Theres definately a tonal difference with heavier strings being more resistant to being flexed, hence suppressing higher harmonics in favour of lower ones. Its why we need wound strings or else a very thick plain string with enough mass to achieve a low note would resist bending into high harmonics and sound more like a piano. Also, with heavier acoustic strings, a wound G is often used. Wound strings add tbe requured mass without adding bending stiffness. Thanks a lot for the explanation! There's one thing I cannot make clear to myself... about the difference between piezos and magnetic passive pickups. Now, what I get is that the passive magnetic pickups sample a frequency dependent signal, and the higher harmonics you have with the strumming, the less they can read that. But the RLC resonances electrical properties make for an overall "flat" response, because they compensate all of that low end thanks to their huge Q of the resonant peak, which is quite high in frequency...leave alone for a second the position of the pickups and the strumming in regards to the stiffness of the strings, the damping etc. Is this correct (please forgive my language...)? The piezos instead. Really they can read a full frequencies, full harmonics signal of the strumming, so that the only thing that changes is the voltage? If it is more or less like this, it would seem, indeed, that both have an overall flat response as the final result. Have I understood right what you meant about the final effect of the two systems? Thank you again!
|
|
|
Post by antigua on Jul 25, 2017 14:18:58 GMT -5
Thanks a lot for the explanation! There's one thing I cannot make clear to myself... about the difference between piezos and magnetic passive pickups. Now, what I get is that the passive magnetic pickups sample a frequency dependent signal, and the higher harmonics you have with the strumming, the less they can read that. But the RLC resonances electrical properties make for an overall "flat" response, because they compensate all of that low end thanks to their huge Q of the resonant peak, which is quite high in frequency...leave alone for a second the position of the pickups and the strumming in regards to the stiffness of the strings, the damping etc. Is this correct (please forgive my language...)? The piezos instead. Really they can read a full frequencies, full harmonics signal of the strumming, so that the only thing that changes is the voltage? If it is more or less like this, it would seem, indeed, that both have an overall flat response as the final result. Have I understood right what you meant about the final effect of the two systems? Thank you again! It's not the RLC filtering that does it, it's due specifically to Faraday's law, which applies to regular pickups, but not piezo pickups. Faraday's law of induction says that the quicker the magnetic field changes, the more voltage you get. Higher frequency equates to quicker magnetic change. Therefore, the higher harmonics, though physically smaller, produce proportionately more voltage because they're moving more quickly (are of a higher frequency) than the lower harmonics. You can even see this at play in the spectrographs I've posted, you should see nothing from about the 4th line from the bottom (the glowing, horizontal yellow red lines), but thanks to Faraday's law, you see many harmonic lines, several dozen at least, reaching up to several kHz. So the magnetic circuit is producing this strong voltage with those high frequency harmonics, but then comes the next block, the RLC filtering of the pickup. Even though the magnetic field is trying to produce voltage at frequencies as high as 10kHz, the RLC filter dictates that no frequencies above, say, 4kHz, or whatever the resonant peak it, will actually make it to the guitar amp. Where the RLC filtering limitation comes in is mostly due to the capacitance "C". The inductance "L" continues to increase the impedance as frequency rises, which is good, but then it hits the resonant peak, where the inductance and capacitance of the coil are equal and opposite, and above that point, the capacitance has a greater effect than the inductance, and instead works like a capacitor, and the impedance, and therefore the voltage, now drops. That's why, if a coil has less capacitance, it's resonant peak is higher, the frequency can rise to a higher point before the capacitance takes over. That's why low capacitance cables or "scatter wound" pickups are more sought after.
|
|
|
Post by wgen on Jul 25, 2017 17:36:08 GMT -5
Thanks a lot for the explanation! There's one thing I cannot make clear to myself... about the difference between piezos and magnetic passive pickups. Now, what I get is that the passive magnetic pickups sample a frequency dependent signal, and the higher harmonics you have with the strumming, the less they can read that. But the RLC resonances electrical properties make for an overall "flat" response, because they compensate all of that low end thanks to their huge Q of the resonant peak, which is quite high in frequency...leave alone for a second the position of the pickups and the strumming in regards to the stiffness of the strings, the damping etc. Is this correct (please forgive my language...)? The piezos instead. Really they can read a full frequencies, full harmonics signal of the strumming, so that the only thing that changes is the voltage? If it is more or less like this, it would seem, indeed, that both have an overall flat response as the final result. Have I understood right what you meant about the final effect of the two systems? Thank you again! It's not the RLC filtering that does it, it's due specifically to Faraday's law, which applies to regular pickups, but not piezo pickups. Faraday's law of induction says that the quicker the magnetic field changes, the more voltage you get. Higher frequency equates to quicker magnetic change. Therefore, the higher harmonics, though physically smaller, produce proportionately more voltage because they're moving more quickly (are of a higher frequency) than the lower harmonics. You can even see this at play in the spectrographs I've posted, you should see nothing from about the 4th line from the bottom (the glowing, horizontal yellow red lines), but thanks to Faraday's law, you see many harmonic lines, several dozen at least, reaching up to several kHz. So the magnetic circuit is producing this strong voltage with those high frequency harmonics, but then comes the next block, the RLC filtering of the pickup. Even though the magnetic field is trying to produce voltage at frequencies as high as 10kHz, the RLC filter dictates that no frequencies above, say, 4kHz, or whatever the resonant peak it, will actually make it to the guitar amp. Where the RLC filtering limitation comes in is mostly due to the capacitance "C". The inductance "L" continues to increase the impedance as frequency rises, which is good, but then it hits the resonant peak, where the inductance and capacitance of the coil are equal and opposite, and above that point, the capacitance has a greater effect than the inductance, and instead works like a capacitor, and the impedance, and therefore the voltage, now drops. That's why, if a coil has less capacitance, it's resonant peak is higher, the frequency can rise to a higher point before the capacitance takes over. That's why low capacitance cables or "scatter wound" pickups are more sought after. Thank you, much appreciated! I was just thinking about your spectrographs. If I understood correctly, those are showing: Faraday's law, plus the electrical properties of the pickups, all at the same time, aren't they? As "electrical properties" I'm referring to those "mountains", the actual tonal response of a passive pickup we talked about earlier. What I don't get is why the tonal response is that "flat", or "balanced", in a system like this, instead... don't know how to put this, but...from Guitarfreak, but I think that the glowing lines of your spectrographs are showing the same, it seems to me that the fundamentals have the same, or maybe even a stronger, amplitude in respect to the higher harmonics, ie those around several kHz. But, if I look at those "mountain", plus considering the Faraday's law, I would expect to have some major treble or high mids response as the final result. What I don't get is why the fundamentals are that strong in the spectrographs and in Guitafreak, if the higher harmonics are producing more voltage. I'm re-reading your post and maybe the answer is where you say, about the higher harmonics: "though physically smaller". So, my question could, maybe, simply be: are guitar fundamentals really that strong to balance out the overall, final result of this system, "everything included"? I hope this is understandable. Don't the piezos read these strong fundamentals, instead? If Faraday's law doesn't apply with these, nor their own response has that "mountain" peak because they have a flat eq by themselves, shouldn't the overall final result of this system be quite bassy and with higher harmonics way too attenuated? Maybe they read an equal amplitude for all the harmonics of a strum? ie fundamentals has the same amplitude of 2nd, 3rd, 4th harmonics, and so on If it was like this it would explain why they have a "flat", "balanced" response, too Thank you very much anyway!
|
|
|
Post by antigua on Jul 25, 2017 21:17:46 GMT -5
Thank you, much appreciated! I was just thinking about your spectrographs. If I understood correctly, those are showing: Faraday's law, plus the electrical properties of the pickups, all at the same time, aren't they? As "electrical properties" I'm referring to those "mountains", the actual tonal response of a passive pickup we talked about earlier. What I don't get is why the tonal response is that "flat", or "balanced", in a system like this, instead... don't know how to put this, but...from Guitarfreak, but I think that the glowing lines of your spectrographs are showing the same, it seems to me that the fundamentals have the same, or maybe even a stronger, amplitude in respect to the higher harmonics, ie those around several kHz. But, if I look at those "mountain", plus considering the Faraday's law, I would expect to have some major treble or high mids response as the final result. What I don't get is why the fundamentals are that strong in the spectrographs and in Guitafreak, if the higher harmonics are producing more voltage. I'm re-reading your post and maybe the answer is where you say, about the higher harmonics: "though physically smaller". So, my question could, maybe, simply be: are guitar fundamentals really that strong to balance out the overall, final result of this system, "everything included"? I hope this is understandable. Don't the piezos read these strong fundamentals, instead? If Faraday's law doesn't apply with these, nor their own response has that "mountain" peak because they have a flat eq by themselves, shouldn't the overall final result of this system be quite bassy and with higher harmonics way too attenuated? Maybe they read an equal amplitude for all the harmonics of a strum? ie fundamentals has the same amplitude of 2nd, 3rd, 4th harmonics, and so on If it was like this it would explain why they have a "flat", "balanced" response, too Thank you very much anyway! The mountain is what you get when you only consider the pickup and Faraday's law in isolation. The fact that the lower strings are thicker and the higher strings are thinner transposes a downwardish slope upon the mountain that results in a flat-ish response. It's not perfectly flat, as you can see, the fundemental and lower harmonics are of a higher amplitude. Some guitar amps and speakers then attenuate the low frequencies to make for a "tighter" sounding bass tone. In some of the spectrograms you see the harmonics suddenly stop around 3 or 4kHz, that's the resonant peak of the pickup eliminating harmonics above 4kHz. But then in the most recent testing I wired the guitar pickup directly without any guitar cable, and so the cut off was much higher, almost 7kHz, so you see the harmonics lines extend that high.
|
|
|
Post by antigua on Jul 25, 2017 21:33:18 GMT -5
** Participation requested **Here is a new sound file I'd like people to listen to a report back on www.echoesofmars.com/misc/hb_wiring_sound_test.wav in order to determine if you canb discern a difference. This sound file contains three strums in a randomized order: 1) A PAF style humbucker in parallel 2) The same PAF split to the coil closer to the bridge 3) The same PAF split to the coil closer to the bridge, but modified to harmonically resemble the humbucker in parallel The strums are not presented in this order, though. Can you guess which is which in the sound file? This is for science. We're assuming that Tillman described comb filtering is what sets split and parallel timbres apart. The question at hand is, can DAW manipulation of harmonics approximate those differences? This is similar to the test I did on page 1, but the difference here is that I've used the same pickup in the same guitar, instead of using sounds from an HH and an SSS.
|
|
|
Post by reTrEaD on Jul 25, 2017 23:06:48 GMT -5
Can you guess which is which in the sound file? Sorry to say, I'm of no help to you on this one. I consider myself to be a discerning listener. The speakers connected to my desktop aren't extremely high quality but they aren't bad. Unfortunately, I can't tell any difference at all between the three. And I listened to them five times in a row. EDIT: I just listened to it about twenty more times. Maybe I hear a slight preference on the B, then the D above it, then the G above that. Maybe. Or perhaps it's just a psychological thing and my mind is searching for a difference. idk. But I'm definitely not recognizing a difference in timbre / harmonic content.
|
|
|
Post by antigua on Jul 25, 2017 23:45:29 GMT -5
Can you guess which is which in the sound file? Sorry to say, I'm of no help to you on this one. I consider myself to be a discerning listener. The speakers connected to my desktop aren't extremely high quality but they aren't bad. Unfortunately, I can't tell any difference at all between the three. And I listened to them five times in a row. EDIT: I just listened to it about twenty more times. Maybe I hear a slight preference on the B, then the D above it, then the G above that. Maybe. Or perhaps it's just a psychological thing and my mind is searching for a difference. idk. But I'm definitely not recognizing a difference in timbre / harmonic content. I have a theory as to why you didn't hear a difference wit PC speakers, but I'll reserve comment, so as to not direct anyone's attention to any particular aspect of the tone. It might be necessary to use headphones.
|
|
|
Post by JohnH on Jul 26, 2017 2:32:02 GMT -5
l tried using 'phones through my phone. But I think this cant do .wav files, I just got noise. Ill try via a pc later.
|
|
|
Post by lunaalta on Jul 26, 2017 7:08:05 GMT -5
I decided to try this test, myself, since I have a pretty good sound system and was sure I would be able to hear any differences, if there were some. With the file loaded into Audacity and later Sonar, playing through a Komplete Audio 6 interface, into Soundcraft close field monitors and also AKG K702 pro monitor headphones, with a suitable quality amplifier. Before listening, I took a sneaky look at the wave forms, and noticed that the audio appeared to have been seriously over recorded, that is, the levels were way too high within the sound file. Off the meters, which max out at +6dB! Nothing can be done about that, since it's very much like having an out of focus negative, no way you can focus it after the event. The expected result was distortion. As a rule, digital recordings should never pass 0dB. Generally, a 'recording' level of no higher than -6dB is acceptable. At 'mastering', i.e. end result sound file, -3dB is considered high, but will be free of distortion. We are talking peak levels, here, not average. Passing 0dB is definitely a no-no, since digital distortion is not a pleasant sound! So, in my opinion, this recording should be considered null and void. As expected, all three sounds were muffled through the monitors and severely distorted through the headphones (damn, those ear muffs are good!). An unpleasant experience...... Fortunately, I had lowered the levels, having seen the wave files. Very fortunately!By the sound of it, the input was way overloaded from the start, or at least mismatched. Sorry, I don't think you can call this a very effective test procedure. I would suggest, (a)using a decent audio interface, or, if you did, (b)reducing the input levels considerably, or, if you did, (c)matching the input characteristics to PU output, or, if you did, (d)not increasing the levels so much during processing of the file. My ears are mostly recovered, now. No serious damage done to my audio equipment, though it sounded like it, initially.....
|
|
|
Post by antigua on Jul 26, 2017 11:46:42 GMT -5
I decided to try this test, myself, since I have a pretty good sound system and was sure I would be able to hear any differences, if there were some. With the file loaded into Audacity and later Sonar, playing through a Komplete Audio 6 interface, into Soundcraft close field monitors and also AKG K702 pro monitor headphones, with a suitable quality amplifier. Before listening, I took a sneaky look at the wave forms, and noticed that the audio appeared to have been seriously over recorded, that is, the levels were way too high within the sound file. Off the meters, which max out at +6dB! ... I'm not sure what you mean. I normalized the strums to the Adobe Audition default "98.8%" , which puts the highest peak just below 0dB. That's how it looks in the wave form also. Here is the amplitude representation of the first strum: I'm also able to discern the differences myself, though I know what I'm listening for. I don't hear any clipping or distortion in through my Sony MDR-7506 headphones. If you want me to do something different, I'd need to know more specifically how this audio falls short. Just using a better sound card, or using lower levels, would be taking a shot in the dark if I don't specifically know what deficiency I'm attempting to correct. As far as I can tell, there is no clipping or data destruction, so if you just want a wav with reduced levels, I can make one fairly easily.
|
|
|
Post by stratotarts on Jul 26, 2017 12:54:51 GMT -5
I looked at your sound file in Audacity. One channel is a square wave. The other channel looks compressed - it is almost at max volume.
|
|
|
Post by antigua on Jul 26, 2017 13:02:54 GMT -5
I looked at your sound file in Audacity. One channel is a square wave. The other channel looks compressed - it is almost at max volume. I'm just not seeing what you're seeing. I've zoomed in on a portion, the wave forms are not squaring off when I look at the file.
|
|
|
Post by lunaalta on Jul 26, 2017 13:05:48 GMT -5
It falls short because it has a lot of distortion within the sound sample. Quite simple, really. All I can say, is, I hear a lot of high frequency distortion from your sound samples when listening with my (professional quality) headphones. It sounds very much like input mismatching, but I can't be sure, of course....
Perhaps describing your input path would help. What input are you using to your computer recording system? The audio interface I use is set up to accept instrument inputs (why I mentioned it)(in fact, my set up is for recording and mastering music), which the average computer is not.
What kind of normalising are you doing in Adobe Audition? And from what original peak signal level?
Both of the above could cause distortion in your signal.
May I suggest using Audacity (also free) as your recording DAW for this experiment? I can assure you, it comes very highly recommended.
Perhaps not normalising would be better.
Please don't take my comments as a sleight, they are not intended to be.
Believe me, I would not have commented if I had not heard serious distortion.....
|
|