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Post by Charlie Honkmeister on Feb 16, 2017 16:55:00 GMT -5
It looks like that small exciter coil has a horizontal axis. Should it not be vertical to align with the most sensitive direction of the pickup coils? The relative sensitivity of the pickup to other axes may not be consistent with their main axes. I'd suspect the single pickup is being relatively under reported in this case compared to the Hb. ... The 7dB spread between the Fideli'tron and the SSL-1 is pretty close to thge difference I saw with pickups in the neck position, so even though this method of excitation and measurement is a lot different, at least the difference in output are in the same ball park. The major drawback of the exciter method is that the loudness boost you might get from a ceramic magnet instead of AlNiCo is not represented. I think I will have to go back to the strumming strings method to get values for magnet types. My belief is that the traditional AlNiCos are all very close, but that AlNiCo 8 or ceramic magnets will boost the output. Based on my experience with magnet swapping I think it could easily be a 3dB boost. When you slide a ceramic magnet into a PAF, the boost in output is fairly audible. Since you have just about "normalized" the Fidelitron and the SSL-1 based on roughly equal inductance and DCR, the 7 dB difference looks pretty valid and the sideways "thin" exciter coil idea looks like it works well. You have the benefit of being able to use using the same positioning and orientation for both single coil and humbucker configurations and could extend to other PU types such as mini-hums, P-90's, bass PU's , etc. Nice job!
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Post by ms on Feb 16, 2017 19:15:38 GMT -5
I doubt that you get the direct eddy current affect right unless you use a coil causes a field very much like the field the string makes.
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Post by Charlie Honkmeister on Feb 16, 2017 20:28:32 GMT -5
I doubt that you get the direct eddy current affect right unless you use a coil causes a field very much like the field the string makes. It wouldn't be too hard to get close, or at least, consistent enough to make meaningful measurements. If you could get the right signal power level to the coil and use the right drive waveform, maybe an artificially tweaked one with emphasized high frequency content, I think you could make meaningful eddy measurements. It would be worth experimenting with.
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Post by antigua on Feb 16, 2017 23:00:55 GMT -5
As discussed here before, there are two different vectors of eddy currents, those that come from the moving magnetized string, and those that comes from the coil's own magnetic field. This exciter coil concern would only apply to eddy currents with respect to the guitar string.
The strongest magnetic concentration is in the very center of the coil over the pole pieces, for obvious reasons, but that also applies to string-related eddy currents, the eddy currents are strongest at the center, by that same token. The pole pieces and the portion of cover above the pole pieces are the strongest source of eddy current opposition, as can be seen in particular with Filter'tron style humbuckers and their dramatic eddy losses. We removed the screws of the Filter'tron to find that the eddy currents disappeared almost completely as a result. Since the exciter coil is managing to deliver flux at the poles, I believe that it is reproducing the vast majority of eddy losses that are to be incurred in situ. What it would miss out on is the farther edges of the humbucker, far away from the exciter coils flux path, but I don't thing the eddy current losses are all that great there in situ, since the sides are so far off axis form the string. Also, as I understand it, since the sides are thin and vertical, the flux path runs parallel to those side walls, where as eddy current movement is perpendicular to the flux line.
The eddy current losses are plain to see in the bode plots, so even if by chance we're not recreating all of them by limiting the area of excitation, I think we do observe the predominant trends. For example these statements are all probably very true: brass covers greater eddy losses than nickel silver to the tune of several dB, any cover causes a loss to the tune of several dB, Strat pickups have less losses than PAFs, which have less losses than Filter'trons, etc.
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Post by antigua on Feb 17, 2017 2:14:48 GMT -5
Here's some data. The exciter coil was driven with 1Vpp, and the dBV is measured at 500Hz. The exciter coil is sideways over the humbuckers, and sideways but only half covering the single coils. Just a reminder, these values would all be further modified by differences in magnetic strength of the pickup, for example I expect that the Super Distortion with it's 1/4 ceramic bar would be even louder than is suggested here. Having said that, the practical testing showed that this difference is not all that great, and that it does require some extreme magnetism, such as a 1/4 ceramic bar to get real amplitude boost. (sorted by dBV) Pickup | R (k ohms) | L (H) | dBV | Type | DiMarzio Super Distortion | 14.61 | 6.57 | 9.5 | HB | Donlis neck humbucker | 7.52 | 4.147 | 8.0 | HB | Fender Fideli'tron | 5.13 | 2.785 | 7.7 | HB | Fender MIM Strat Bridge | 7.17 | 4.361 | 6.0 | single | DiMarzio Humbucker from Hell | 5.92 | 2.31 | 5.6 | HB | Seymour Duncan SSL-4 | 13.62 | 6.864 | 4.7 | single | Seymour Duncan Texas Hot Bridge | 10.11 | 3.491 | 1.9 | single | Seymour Duncan SSL-1 | 6.67 | 2.628 | 1.4 | single |
The added output of the humbucker format is plain to see, especially in the Humbucker from Hell and the Fideli'tron, which have L and C values that are below the SSL-1, and yet they both show much greater dBV output, 4dBV and 6dBV respectively. Here are the bode plots: HumbuckersSingle coilsI see something interesting... the SSL-4 has a higher L and R values than the Fender MIM ceramic/steel pickup, and yet the MIM is about 1 to 1.5dBV higher output, depending on the frequency. A similar oddity is between the Fideli'tron and the Donlis humbuckers; the Donlis has a much higher L and R, but only a small 0.3dBV increase in output. What do the to two higher-than-expected pickups (MIM ceramic single and Fideli'tron) have in common? More substantial volumes of permeable material. The MIM ceramic has steel poles while the SSL-4 has large AlNiCo slugs, and the Fileli'tron has large steel screws, relative to the Donlis. I speculate that the higher permeable cores make the pickups louder by magnifying the magnetic field of the exciter coil. It makes sense that it happens, that's why any inductor has a core, but I would never have guessed that the effect would provide so much assistance to the guitar string's magnetic field as well. This same magnification effect would happen with guitar strings, though. If it's true that steel poles make a pickup louder by way of EMF magnification. This might be a novel observation, that steel poles make a pickup louder, but by how much? The inductance of the MIM steel ceramic is right in between the Texas Hot bridge and the SSL-4, and their amplitudes are 1.9dBV and 4.7dBV, so we should expect that the MIM cermaic steel should have a dBV of about 3.3dBV, but it's in fact 6.0dB, so it looks like the steel poles give it a boost of about 2.7dBV. This makes a good case for laminated steel pickup core, so that you can get this higher output from that higher permeability slug, but without the eddy currents associated with steel slugs. --- Another thing, the Texas Hot bridge is only showing 0.5dBV higher output than the SSL-1, which almost seems like an error, as this is a pickup that is supposed to be louder. It has nearly 1 henry higher inductance than the SSL-1. I'm not even surprised by the small dB boost as much as I am surprised that a pickup that is not really any louder is a "hot bridge". I speculate that these overwound pickups such as the Texas Specials are not really louder at all, and that it's merely the lower resonant peak that both makes them perhaps seem louder, and make the palatable has bridge pickups, or overdrive friendly pickups. Prior to the test I would have thought that there would be balance problems between say, CS 69's, and Texas Specials, but I'm pretty convinced that it makes for a tonal mismatch, and not one of amplitude. This lends credibility to the idea of tone shaping pickups with capacitors, if you want to say, make a '59 sound like a Pearly Gates, or a CS 69 sound like a Fat 50, because the argument before would have been that a cap is not going to push your amp any harder, but if 1 henry of inductance only increases the output by 1dB, I don't see how it could be pushing the amp harder, except at the resonant peak, which is now placed at a lower, more audible frequency.
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Post by Deleted on Feb 17, 2017 8:40:39 GMT -5
great work... keep it coming.
I'd love to see some EMGs , duncans blackouts in the mix along with dimarzio X2N.
Also I'd love to see some study on actual noise (50/60Hz) reduction on various designs.
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Post by antigua on Feb 18, 2017 3:36:42 GMT -5
Here's another data point to consider; a PAF knock off is series, parallel, and split to slug and screw: As you can see, the series mode has an easy 5.0dBV higher output than the parallel or split modes, but interestingly there is an equivalence between parallel and split. So with the parallel mode, obviously the resistance is halved, and the inductance is nearly halved, so the voltage should drop, but wait! you get EMF from both coils instead of just one or the other, so the voltage output is doubled, bringing it back up to what either coil puts out alone. Something that seems obvious when you think about it, but is fun to see happen in a practical demonstration. One thing I don't really understand too well is the distinction between the inductance and resistance in terms of defining the output voltage. Is this more V = I*R, or V = I*Z? So if the output for both parallel and split is, rounded to 1.20Vrms, the resistance for each coil alone is about 3.7k ohms, so the current would therefore be 324uA, and in parallel the resistance is 1.85k, which means the current would be 648uA, twice the current for twice the total area of coil. So in parallel you get twice the current, but half the resistance, or reactance, and so the total output voltage end up being a wash. ~~~*~*~*~~~*~**~*~~~~~ In other news, I received my first guitar with P-90s, and I played if for about fifteen minutes so far, but I can tell you the P-90's obviously have a low resonant peak and an overall dar character, as I expected they might. But it raises a question: why can a P-90 neck pickup get away with a 6 henry / 2kHz P-90 sound good as a neck pickup, but if you use this same recipe for a PAF you get a muddy pickup? Most neck PAF's are closer to 4.5 henry / 2.kHz. Maybe the higher voltage output of the humbucker format, or the wider sampling of harmonic nodes creates a composition of harmonic content that is simply less flattering with you have a lower resonant peak. I'll do a bode plot of those P-90's soon so that we can see exactly how their response curves look.
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Post by ms on Feb 18, 2017 6:44:31 GMT -5
Here's another data point to consider; a PAF knock off is series, parallel, and split to slug and screw: As you can see, the series mode has an easy 5.0dBV higher output than the parallel or split modes, but interestingly there is an equivalence between parallel and split. So with the parallel mode, obviously the resistance is halved, and the inductance is nearly halved, so the voltage should drop, but wait! you get EMF from both coils instead of just one or the other, so the voltage output is doubled, bringing it back up to what either coil puts out alone. Something that seems obvious when you think about it, but is fun to see happen in a practical demonstration. One thing I don't really understand too well is the distinction between the inductance and resistance in terms of defining the output voltage. Is this more V = I*R, or V = I*Z? So if the output for both parallel and split is, rounded to 1.20Vrms, the resistance for each coil alone is about 3.7k ohms, so the current would therefore be 324uA, and in parallel the resistance is 1.85k, which means the current would be 648uA, twice the current for twice the total area of coil. So in parallel you get twice the current, but half the resistance, or reactance, and so the total output voltage end up being a wash. ~~~*~*~*~~~*~**~*~~~~~ In other news, I received my first guitar with P-90s, and I played if for about fifteen minutes so far, but I can tell you the P-90's obviously have a low resonant peak and an overall dar character, as I expected they might. But it raises a question: why can a P-90 neck pickup get away with a 6 henry / 2kHz P-90 sound good as a neck pickup, but if you use this same recipe for a PAF you get a muddy pickup? Most neck PAF's are closer to 4.5 henry / 2.kHz. Maybe the higher voltage output of the humbucker format, or the wider sampling of harmonic nodes creates a composition of harmonic content that is simply less flattering with you have a lower resonant peak. I'll do a bode plot of those P-90's soon so that we can see exactly how their response curves look. Neither resistance nor inductance directly defines the output voltage. The results from combining the two coils in series or parallel are very much consistent with the individual measurements, but to see this you need a better understanding of the fundamentals of circuit analysis.
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Post by antigua on Feb 18, 2017 14:12:28 GMT -5
Neither resistance nor inductance directly defines the output voltage. The results from combining the two coils in series or parallel are very much consistent with the individual measurements, but to see this you need a better understanding of the fundamentals of circuit analysis. Correct or incorrect, at least the data is there for others who are more educated in these matters to interpret and explain. I'm just looking at Ohm's law and Faraday's law of induction and trying to connect the dots. I don't know that I'm getting it wrong until someone explains how I'm getting these principles mixed up, or I serendipitously come across new information that sets me straight. I don't want to be the one who's trying to figure this stuff out, I'd much rather be reading about why a pickup has equal output voltage parallel or split, but since nobody else is on the case, by bad science is the best I've got.
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Post by antigua on Feb 18, 2017 14:43:29 GMT -5
Here is the amplitude test performed on the tappable SSL-4. This pickup has an overall DC resistance of 13.7k, but splits into not quite equal halves, with a third red wire in between the two halves. Though I can't be sure, it appears that the white wire is the start of the wind, and the black wire is the end of the wind, so taking the red and white wires as lead and ground would give you the inner portion of coil while red and black would give you the outer portion of coil. It appears that tapping the SSL-4 drops the output by 5.3dBV, and though the two way of tapping the the coil result in different coil geometries (wider coil with wider coil, narrow coil with narrow core), they put out the same output voltage. The inductance and resistances of the two halves differ slightly. The lower inductance of the white+red portion of coil (green line) is corroborated by it's slightly higher resonant peak. As mentioned in the SSL-4 review, those tapped resonant peaks are lower than they should be for 1.9H or 1.6H inductance, because the other half of the coil that is out of circuit is still capacitively in the circuit, to the tune of 600pF or more. Not only should those resonant peaks be higher if these were lone coils, but they shouldn't be so close together, either.
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Post by JohnH on Feb 18, 2017 14:44:56 GMT -5
Your tests show that the series/single/parallel relationships are more subtle than I had thought. But, its still worth stating the simplistic mental picture, in order to see how reality diverges from it.
If coils within a humbucker were identical and completely separate non-interacting components, and if the load on them was very small, and if a simple RLC model was accurate, we would then expect series to be 2x single output voltage ie +6db higher. We would expect single and parallel to be the same basic output voltage. This would all apply in the lower to mid frequencies below resonance.
An analogy to this is with two 1.5V dc battery cells. Put them is series for x2 voltage ie 3V, but put them in parallel and you get the same voltage 1.5V.
Then moving up into resonance with this simplistic world view, we expect inductance and resistance to double in series compared to single, and to halve for parallel compared to single. But, at he same time, effective capacitance is changing too and the self capacitance is x2 for parallel and x1/2 for single assuming these hypothetical independent coils. So in theory, self resonant frequencies, with no added caps, would all be the same because x2 on capacitance would be combined with x1/2 inductance so that LC is the same.
But none of that necessarily relates directly to voltage output level, and also, in real cases, the relationships vary significantly. But its very interesting to observe these variations and to try to understand them.
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Post by antigua on Feb 18, 2017 14:48:27 GMT -5
I just posted some new data a few minutes ago regarding tapped coils that is now one page behind us, just i n case anyone misses it guitarnuts2.proboards.com/post/80442/threadAn analogy to this is with two 1.5V dc battery cells. Put them is series for x2 voltage ie 3V, but put them in parallel and you get the same voltage 1.5V. But isn't the voltage maintained because you have twice the current? If one of those two batteries dies, then the dead battery becomes a parallel resistor, dropping the overall voltage, depending upon the resistance of the dead battery. So the point I'm getting at is it seems that the two sides of the parallel humbucker only behave as two batteries because both coils generate a current, as opposed to a parallel dummy coil, like a stacked humbucker, where the dummy coil is not a substantial contributor to signal current, not behaving like a battery.
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Post by ms on Feb 18, 2017 17:20:29 GMT -5
I just posted some new data a few minutes ago regarding tapped coils that is now one page behind us, just i n case anyone misses it guitarnuts2.proboards.com/post/80442/threadAn analogy to this is with two 1.5V dc battery cells. Put them is series for x2 voltage ie 3V, but put them in parallel and you get the same voltage 1.5V. But isn't the voltage maintained because you have twice the current? If one of those two batteries dies, then the dead battery becomes a parallel resistor, dropping the overall voltage, depending upon the resistance of the dead battery. So the point I'm getting at is it seems that the two sides of the parallel humbucker only behave as two batteries because both coils generate a current, as opposed to a parallel dummy coil, like a stacked humbucker, where the dummy coil is not a substantial contributor to signal current, not behaving like a battery. If you put two ideal batteries in parallel, the total current stays the same. It is a function of the load on the batteries, which is the same in both cases.
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Post by antigua on Feb 18, 2017 17:36:28 GMT -5
Are two parallel pickup coils with a moving string above them the same, or different, than two batteries in that respect, or is that an open question?
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Post by JohnH on Feb 18, 2017 18:08:35 GMT -5
I think the parallel battery analogy is valid for two pickups in parallel, assuming:
Load on the pickup is very small/negligible as in a unloaded test, so current is very small, so it does not load down the battery/pickup hence reducing its voltage. (two batteries, or one bigger battery, all at the same voltage can supply more current than one small one, but this is not significant if load is high, current is small)
The two pickups have no interaction magnetically or inductively
They both see the same string vibration, so no phase or comb effects.
If you had two pickups in parallel, but one was separated from the string so it could not generate signal, this would be a bit analogous to one of two parallel batteries being dead. In the case of the pickups, output voltage would be halved. (but the battery analogy starts to fall apart here, a dead battery may have more internal resistance than a good one)
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Post by antigua on Feb 18, 2017 19:06:20 GMT -5
Here is a true "with/without parallel dummy coil" test, this picture shows the scenario: And it can be seen that there is a -5.7dB drop for placing the dummy coil of 3.7k DC resistance/1.8H inductance in parallel with a pickup coil of the same values. Now, if that "dummy" coil is put back into the pickup body per usual, and that the exciter coil is now feeding flux to both coils equally, the voltage output is now the (more or less) same as one coil by itself with no dummy coil: Notice that when the two coils are "active" and in parallel, we get the same voltage output as the one coil by itself, but you see that it has the parallel mode resonant peak. I'm not saying this proves of disproves anything that been said, but this all conforms to what I understand about Ohms and Faraday's laws, that for a given induced current, if you halve the resistance, you get half the voltage, as seen by adding and removing a parallel dummy coil, but by doubling up on the current by restoring the pickup to two "productive" coils, you retain the voltage on just one coil by itself, despite having halved the resistance across the whole pickup.
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Post by ms on Feb 19, 2017 6:39:00 GMT -5
I'm not saying this proves of disproves anything that been said, but this all conforms to what I understand about Ohms and Faraday's laws, that for a given induced current, if you halve the resistance, you get half the voltage, as seen by adding and removing a parallel dummy coil, but by doubling up on the current by restoring the pickup to two "productive" coils, you retain the voltage on just one coil by itself, despite having halved the resistance across the whole pickup. When you connect the second coil but do not excite it, it acts as a load equal to the source impedance of the excited pickup, and so you get half the voltage of the excited coil by itself with no load. When the excited coil operates by itself with no load, there is (ideally) no current flowing (at low frequencies). The change in resonance frequency probably indicates that you have some capacitance in the measurement setup.
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Post by wgen on Mar 17, 2017 16:31:32 GMT -5
For my pickup database's RLC plotting feature, I needed some realistic offsets to express the loudness difference between different pickup classes. Pickups have RLC characteristics that are relatively easy to acquire, but the actual amount of output voltage is dependent upon the amount of magnemotive force that traverses the pickup's coil(s). Here's some dB levels I got from five guitars, three Strats, one with A3 and one wih A5 pole pickups, one with SSL-5's that can tap in all three positions, one guitar with Filter'trons and one with PAF clones. For each guitar, the pole pieces were set to be exactly 4.5mm away from the strings (which is rather low). On the Strats with staggered poles, I went by the outer most pole pieces. The guitars were plugged straight into a Boss ME-80 (1 meg input impedance), then into a laptop via the USB connection. I recorded the sample with Adobe Audition and then acquired the average RMS amplitude from exactly the first two seconds of the strum. There are no extra gain stages or EQ, at least none that are user facing. I briskly strummed an open E chord, getting the string about an inch away from the neck pickup of each guitar, one inch in the direction of the bridge, so on a Strat, that's right in between the neck and middle pickup. All of the pickups are in different guitars, but all have the same strings, Elixir .010-.046 coated electric guitar strings. The MIM A5 Strat and SSL-5 tapped pickups bridge positions had the lowest output, so I made that pickup the baseline, it shows zero, and the rest are some dB above that pickup. That value was -42.27, so +42.27 dB has been added to all the values to make them easier to compare. As an aside, I made a sort of discovery in the process; in the past I would pluck a single string, usually the D just to keep things clean, but I got very mixed results between humbuckers and single coils, and it occurred to me that the comb filtering of a wider PAF will selectively make particular harmonics weaker, so even though a PAF might be stronger than a single coil overall, comb filtering might make the "open D" weaker than it would be otherwise. The wider a pickup is, the more comb filtering occurs. Therefore, to compare a single coil to a humbucker, you have to either find a note that doesn't fall into the comb filter, or much easier, strum all six strings so that you get an assortment of harmonics that don't fall into the filtering. The phenomena of comb filtering is covered by J Donald Tillman www.till.com/articles/PickupResponse/ position / dB / inductance L & DC resistance RStrat MIM AlNiCo AlNiCo 5 in Fender Strat B 0 (L: 2.2 R: 5.8k) BM 3.56 M 8.57 (L: 2.2 R: 5.8k) MN 8.54 N 8.44 (L: 2.2 R: 5.8k)
Strat 60th Anniv AlNiCo 3 in Fender Strat B 0.07 (L: 2.5 R: 6.0k) B 2.15 M 4.52 (L: 2.5 R: 6.0k) MN 8.61 N 8.52 (L: 2.5 R: 6.0k)
Strat SSL-5 (AlNiCo 5) high output pickup in a Strat N 2.59 (L: ~6 R: 12.9k ) BM 6.93 M 11.54 (L: ~6 R: 12.9k ) MN 12.69 N 12.46 (L: ~6 R: 12.9k ) Strat SSL-5 (AlNiCo 5) tapped pickup in a Strat N 0.00 (L: ~2 R: 6.6k ) BM 2.73 M 5.98 (L: ~2 R: 6.6k ) MN 7.49 N 6.24 (L: ~2 R: 6.6k )
Filter'tron, Gretch in Fender Cabronita B 5.38 (L: 2.3 R: 5.0K) BN 7.83 N 9.8 (L: 1.7 R: 4.2K)
PAF clone Tonerider AlNiCo IV in Epiphone Les Paul B 7.08 (L: 5.5 R: 8.2k) BN 12 N 12.45 (L: 4.6 R: 7.1k)
Strat Lollar Blondes AlNiCo 2, flat poles N 2.85 (L: 2.7 R: 6.0) BM 5.22 M 6.21 (L: 2.5 R: 5.8) MN 7.30 N 9.50 (L: 2.2 R: 5.6k)
There is a large amount of variability in the data as far as what it represents, since I can't be sure I strummed with the same intensity for each sample, so the best I can do is look for broad trends. I would have liked to sampled more pickups, and using more methods, but this is tedious work and time is limited. Hopefully I can get more data later. I will also have a set of P-90's soon, and I'm looking forward to adding them to the mix. A major complication is that these pickups all have different RLC values, so it can't be clearly see what difference owes to geometry, and those which owe to differences in impedance. In general, Strat pickups rarely come close to PAF RLC values. I have an SSL-5 test subject, but it's inductance actually shoots past the PAFs. The Filter'trons have inudctances that are closer to the Strat pickups and serve as a decent point of comparison. First thing of note is that the Strat AlNiCo 3 and AlNiCo 5 pickups appear to be equally loud. The AlNiCo 5 produces twice as much flux density as AlNiCo 3, but it doesn't matter too much, apparently. The explanation for this is probably that while the absolute flux might be a lot higher, but the flux difference within the string's travel isn't all that great. When you have a stronger magnet, it's not just the maximum flux that is higher, but also the minimum flux. The AlNiCo 3 is wound a little hotter than the AlNiCo 5 pickups (and the AlNiCo 3 increases the inductance by itself), and that might cause a compensation that brings the AlNiCo 3's output closer to the AlNiCo 5 pickup, but they're still very close regardless. In general, the two lower output Strat pickups have a dB spread 0dB to 8dB, bridge to neck, while the PAF clone was 7dB to 12dB, and the Filter'tron was 5dB to 10dB. Note that the while the PAF clone has an inductance of 5.5H and 4.6H, the Filter'tron only has 2.3 AND 1.7H, even less than the average Strat pickups. From that it can be inferred that the voltage output is hugely increased by the side-by-side humbucker layout. Based on this data, you might assume that the humbucking layout adds 5 to 7dB at the bridge position, and 2 to 4dB at the neck. This greater dB difference seen in the bridge makes sense, since the humbucker bridge pickup extends away from the bridge, exposing it to greater string displacement. The SSL-5 has the highest inductance of all the pickups tested, around 6 henries, and so it's interesting to see how that high inductance Strat pickup fits with the observation of the previous paragraph, and in full 6 henry mode, the bridge to neck spread is 3dB to 12dB. So in the bridge position, it's only 3dB louder than the "average Strat pickup" and still 3 to 5dB quieter than the two humbuckers in the bridge position. But the SSL-5 in the neck is another story, at 12dB it's just as loud as the PAF clone neck with 4.6H inductance, and louder than the Filter'tron neck with 1.7H inductance. This goes to show that a high wind count can on a Strat pickup will allow it to achieve the voltage output of a typical PAF in the neck position, but perhaps not in the bridge. Another data point is the SSL-5 full versus tapped. Tapped the SSL-5 is a little weaker than the "average Strat pickups", but it also likely has a lower inductance, as that's only 6.6k DC resistance of 43 AWG wire. The tapped inductance is likely right around 2 henries, based on measurements of the very similar tapped SSL-4. The tapped SSL-5 shows output levels that are only slightly lower than the "average Strat pickups". An interesting fact about tapped coils is that they have a crazy high capacitance do to the presence of the unused portion of coil, so despite the low inductance, their have a resonant peak similar to a higher inductance Strat pickup, and that likely contributes poor opinions about tapped pickup tone. I also have middle pickup and in between dB levels in the table, but I've chosen not to analyse those for now. There's way more to be said about this, but my first post conclusion is that it's safe to say a humbucker gives you a boost in the ballpark of 3dB in the bridge, and the 6dB in the neck, all other things being equal. There's also clearly a scale difference between the bridge and neck. The extreme spread of the SSL-5 goes to show that doubling the nearly tripping the inductance of a Strat pickup gets you an additional 6dB in the neck, but only an additional 2 to 3dB boost in the bridge. I'm re opening this thread to ask if eventually someone ever considered the measuring of a pickup output in millivolts peak to peak. I think I can imagine why it shouldn't be done; first of all, playing which string? ie an open D string would lead to different results than an open low E string I guess. Then, which distance from the string we are talking about...Antigua in another thread measured, with an Ebow, around 6 dB of difference in output for every 3 mm the pole piece distance from the string changes, and I read on the Sengpielaudio web page that, for example, 6 dB more for a given signal should equal double the voltage, so this would represent a great difference in millivolts in first place, and so on... Also, I don't know, but I could imagine that a thicker string gauge, with more tension for a given note, would provide more signal output than a lighter gauge string, and also, a light touch would be different from a heavy plucked note of course. I'm asking this just because it's some time now that I'm trying to figure out how the signal is manipulated at a Tube Screamer's output. Here, at some point, Bogac Topaktas claims that a non inverting opamp circuit, like the one at the heart of this pedal, is basically mixing the dry, uneffected signal with the clipped signal: www.bteaudio.com/articles/TSS/TSS.htmlBecause of a typical TS-9 (not sure for the TS-808 because I read that it used different diodes with a different forward voltage drop) diodes are clipping the signal at around 600 millivolts, this means that, no matter what setting of the Drive potentiometer, the effected part of this pedal doesn't allow a signal greater than 600 millivolts out of the pedal's output. The diodes are basically clamping the signal while clipping the waveform. Please excuse my English but I hope you get the idea. But then, we have to keep an eye to the uneffected part of the signal, which should be mixed with the "600 mV max" one. I was really, really interested in how much strenght I can expect from the dry, uneffected signal from the pickups...and, how much the signal is close to the 600 mV mark, in first instance. I'm referring to the peak to peak signal in particular, the transients, not the normalized signal which sometimes I read about on this subject. Thank you very much!
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Post by antigua on Mar 17, 2017 17:31:20 GMT -5
The next time I'm measuring the the output of a pickup, I'll record some Vpp values, too. Hopefully I can get back at it tonight.
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Post by wgen on Mar 18, 2017 4:19:11 GMT -5
The next time I'm measuring the the output of a pickup, I'll record some Vpp values, too. Hopefully I can get back at it tonight. Thank you again, much appreciated!!
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Post by antigua on Mar 18, 2017 16:02:45 GMT -5
The next time I'm measuring the the output of a pickup, I'll record some Vpp values, too. Hopefully I can get back at it tonight. Thank you again, much appreciated!! It was hard to see a consistent Vpp, but with a steel pole piece single coil, with a hard pluck, it seemed to get up to 300 - 400mV Vpp, but usually it was closer to 200 - 300mV at the initial pluck, then dropped to ~150mV and continued down from there as the string decayed. The sample rate of the oscilliscope gives snapshots that bounce around, so it's hard to get a clear picture, but I can tell you that 600mV seems fairly out of reach, as far as I can tell. Maybe a humbucker would reach 600mV, though. I don't know a lot about Tube Screamer circuits, so I can comment much, but maybe they're talking about 600mV at a gain stage, and not the input signal itself.
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Post by JohnH on Mar 18, 2017 16:30:26 GMT -5
I did some rough tests on maximum output voltage a few years ago. My intent was to find the greatest peak signal I could, for the purpose of determining max headroom needed for clean buffer stages. So I was really hitting it hard. I have an Ibanez Strat with very loud ceramic pickups, and my wiring had an all-in-series option! With that and a hard strum, I got up to +/- 3V swing on the initial transients. More typically, my PAF humbuckers do about 1 to 1.5V for that, then much lower as soon as the first transients have passed.
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Post by wgen on Mar 19, 2017 7:32:32 GMT -5
Thank you very much for the tests!! I was mainly interested in this because a typical Tube screamer has a frequency response with a huge bass roll off; if you are leaving the tone knob at max (which is the only way to maintain the treble with this pedal, which would then be cut otherwise, too), you have something like 15 dB cut at 100 Hz with this circuit. But, as you noticed, this is just for the effected part of the signal, the one that is amplified from the gain stage and clipped at 600 mV max by the diodes. The other part of the signal at the mixing opamp isn't touched by any of those elements, so basically your dry signal as you strum is passed from the + input of the opamp directly to the output of that same opamp without any amplification, nor by the clipping of the waveform, and, most of all, it isn't high passed by the RC filter. So, I was interested in understanding how much that -15dB at 100 Hz shouldn't be considered as something to be divided with a flat signal, instead. The point is, if you have a signal, at the Tube Screamer's output, which is the 1:1 ratio of a -15dB @100hz signal as one half, while the other half is basically flat, so let's say 0 dB @100hz, so, you haven't as the final result a -15dB @100hz bass cut signal, but you would have a -7.5dB @100hz, because you are dividing that bass cut in two halves. So, when you are considering the frequency response out of this pedal, maybe it wouldn't be that poor in bass response...yes, of course it still has a low end cut, but not that much as the Electrosmash analysis is claiming, for example. But, this would apply if you had two halves of the same amplitude...this is why I was interested in understanding if the dry, uneffected half of the signal approaches 600 mV or not..! Anyway, we should consider that, even if this part of the signal is weaker, the subsequent elements in the signal chain could be play a role here, because, if you have some compression and sag from your tube amp, or you have other subsequent overdrives which are furthermore compressing the signal, then you still could approach that 1:1 ratio of the two halves of the signal which come out from the Tube Screamer. I hope all of this was clear enough....I guess that even a 200-300 mV dry signal could approach the other, stronger part of the signal, if we consider all of the subsequent elements in a typical signal chain, so that, when the signal comes out from the speakers, in the end, we would still have that 1:1 ratio of the signal, which was initially split in two halves by that Tube Screamer's opamp.
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Post by wgen on Mar 23, 2017 5:29:29 GMT -5
Thank you again, much appreciated!! It was hard to see a consistent Vpp, but with a steel pole piece single coil, with a hard pluck, it seemed to get up to 300 - 400mV Vpp, but usually it was closer to 200 - 300mV at the initial pluck, then dropped to ~150mV and continued down from there as the string decayed. The sample rate of the oscilliscope gives snapshots that bounce around, so it's hard to get a clear picture, but I can tell you that 600mV seems fairly out of reach, as far as I can tell. Maybe a humbucker would reach 600mV, though. Sorry for the double post, I was re-reading your reply and I'd like to ask you if you were strumming hard all the strings or you were playing single notes...in this last case, which note/string were you settled on..? Also, I think that you were playing with a steel pole piece over magnet bar from your post, have I understood right? In this case, the signal would be even stronger than a vintage style, Alnico rod pieces, isn't it? Thank you very much again!
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Post by antigua on Mar 23, 2017 19:38:12 GMT -5
It was hard to see a consistent Vpp, but with a steel pole piece single coil, with a hard pluck, it seemed to get up to 300 - 400mV Vpp, but usually it was closer to 200 - 300mV at the initial pluck, then dropped to ~150mV and continued down from there as the string decayed. The sample rate of the oscilliscope gives snapshots that bounce around, so it's hard to get a clear picture, but I can tell you that 600mV seems fairly out of reach, as far as I can tell. Maybe a humbucker would reach 600mV, though. Sorry for the double post, I was re-reading your reply and I'd like to ask you if you were strumming hard all the strings or you were playing single notes...in this last case, which note/string were you settled on..? Also, I think that you were playing with a steel pole piece over magnet bar from your post, have I understood right? In this case, the signal would be even stronger than a vintage style, Alnico rod pieces, isn't it? Thank you very much again! I'm doing a test again fresh with P-Rails neck pickup / neck position in series with about 10.8 henries inductance, because they're probably the hottest set I have in a guitar, using the PCSGU250 www.amazon.com/Velleman-PCSGU250-Usb-Pc-Scope-Generator/dp/B006DXCO3EHere is an open E chord strummed vigorously for about 30 seconds, with persistence on, so that the waveforms would stack up: The divisions are 1V, so it looks like it maxed potential topped out at 4.19 volts. Interestingly, I see a consistently higher voltage if I play a B chord in the form of open E at the 7th fret: You can see it's a non trivial difference. Here it looks like the peak top peak potential reached 7.38 volts. Per Faraday's law, higher frequency = more voltage, so it's not a surprise that the voltage is higher, but then again it is a bit of surprise because the string displaces less distance the shorter the scale becomes. Here is E chord in open E form at the 12th fret: Note that it is now 3 volts per square, so it's scaled 1/3: Not the peak potential reached up to 8.81 volts. An E chord at the 12th fret doesn't sound that much louder to me than an open E, but the Fletcher Munson curve probably has something to do with that. The P-Rails in series is about 10.8 henries inductance. A bridge PAF is typically close to 5 henry, so this is like a flame thrower of a pickup. The same test with a Strat would yield lower voltages.
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Post by antigua on Mar 23, 2017 19:58:47 GMT -5
Here's the same test performed with a Strat neck pickup , loaded with Donlis DS51, weighing in at 1.9 henries, the polar opposite of the P-Reails in series. Open E; notes that the divisions are only 0.3 volts, so this is zoomed in relative to the above. The best potential voltage appears to be 1.8 volts with vigorous strumming. Here is the B chord played "E" at the 7th fret: There's a potential of 2.3 volts, but I only got that by really pulling on the string. You can see that anything that high is a real oddity, and that it averages around 0.6 volts with vigorous strumming. Finally, E chord at the 12th fret: This time the max potential was 2.0 volts, but you can see that the average ticked up a bit from the 7th fret B chord, still in the area of 0.6 volts.
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Post by wgen on Mar 24, 2017 4:19:14 GMT -5
Here's the same test performed with a Strat neck pickup , loaded with Donlis DS51, weighing in at 1.9 henries, the polar opposite of the P-Reails in series. Open E; notes that the divisions are only 0.3 volts, so this is zoomed in relative to the above. The best potential voltage appears to be 1.8 volts with vigorous strumming. Here is the B chord played "E" at the 7th fret: There's a potential of 2.3 volts, but I only got that by really pulling on the string. You can see that anything that high is a real oddity, and that it averages around 0.6 volts with vigorous strumming. Finally, E chord at the 12th fret: This time the max potential was 2.0 volts, but you can see that the average ticked up a bit from the 7th fret B chord, still in the area of 0.6 volts. Thank you very much for this in depth test! Now this is much interesting....also the comparison between those two different types of pickup. Great!
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Post by JohnH on Mar 24, 2017 4:41:59 GMT -5
Your results whereby the general output level rises at higher frets matches where I got to following through the maths in GuitarFreak. I took as a starting point, that the force with which each string is plucked is constant. That would correspond with using a flexible pick, strumming tbrough the strings so each is released once the pick has flexed a certain amount. One of the main factors leading to the output rise is that at higher frets, each pickup is nearer to the centre of the fundamental mode of vibration of the string, which provides most of the amplitude.
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Post by antigua on Mar 24, 2017 14:16:37 GMT -5
Your results whereby the general output level rises at higher frets matches where I got to following through the maths in GuitarFreak. I took as a starting point, that the force with which each string is plucked is constant. That would correspond with using a flexible pick, strumming tbrough the strings so each is released once the pick has flexed a certain amount. One of the main factors leading to the output rise is that at higher frets, each pickup is nearer to the centre of the fundamental mode of vibration of the string, which provides most of the amplitude. That's a great point, but still non-intuitive, because the shorter scale string displaces less at the center point, than a longer scale string, for a given tension. In other words; which covers more distance: the 2nd harmonic of an open E, or the fundamental of an E played at the 12th fret? The way I see it, this experiment suggests either the fretted E at the 12th fret moves a greater distance, or alternatively, the higher frequency induces fore voltage. It would take some serious math to figure out which is the case.
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Post by gitpiddler on Mar 31, 2017 7:49:42 GMT -5
A good friend has a habit of starting a sentence with "You might think I'm lying but...". My #1 has gotten a neck shave recently. The pickup is an '84 Duncan JB, no cover, hand-potted , direct mounted brick of a pickup. I read some years ago that Neal Schon had trimmed the protruding ends of the pickup baseplate, giving better treble response. Seemed to work on this one though at the time I had no amp to compare before and after. After shaving the neck a little between the 2nd and 5th frets, this guitar on the same pencil-mark amp settings is now as loud on 3 as it was before the shave on 6. The last change I did to this guitar was a QTB treatment, which is easy on a Tele with the jack on the control plate. In short, testing inside the guitar is essential.
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