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Post by antigua on Jan 25, 2022 1:30:43 GMT -5
 I ordered a Les Paul themed guitar from AliExpress, and it's always a surprise to see what corners they've cut do be able to sell a guitar for rock bottom prices. If this were a regular name brand guitar, real EMGs alone would have cost more than the whole guitar. I've bought fake EMGs before, not realizing they were fake until I got them, but in that case they were actual active pickups, but here I find passive pickups with EMG covers and EMG style black epoxy inside. I can't get to the coils without destroying the pickup, but I can see with magnetic film that they have bar magnets. I suspect they are ceramic, due to the high Q factor and relatively high Guass of 325, with plastic cover putting some distance between the probe and the magnets. The inductance for all three pickups is 4 henries, which is like three modern PAF neck pickups. Since the resonant peak is higher, similar to a "Seymour Duncan Jazz", and there is no metal cover, they sound pretty good, as clear sounding as you would expect. Ceramic bar magnets and a low inductance is probably the best one could do to make a passive pickup give the impression of an active pickup, but the output is lower than you'd expect if they were active. I'm still going to replace them with active pickups though, because I was wanting active pickups instead of inductance passives, and I think I can hear the subtle difference in the top end of the frequency response, as well as the lower noise of a low impedance circuit. Once I've put in real active pickups, I might break one of them open see what's in there. Passive Chinese pickups made to look like EMGs
Bridge
- DC Resistance: 11.474K ohms
- Q @1khz: 1.781
- Measured L: 4.138H
- Calculated C: 96.07pF
- Gauss: 325G
Middle
- DC Resistance: 11.370K ohms
- Q @1khz: 1.787
- Measured L: 4.103H
- Calculated C: 96.96pF
- Gauss: 325G
Neck
- DC Resistance: 11.540K ohms
- Q @1khz: 1.784
- Measured L: 4.138H
- Calculated C: 95.60pF
- Gauss: 325G
Bridge unloaded: dV: 9.1dB f: 8.08kHz (black)
Bridge loaded (200k & 470pF): dV: 3.1dB f: 3.13kHz (blue)
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Post by gckelloch on Jan 25, 2022 7:39:22 GMT -5
At least they aren't so high inductance that they can't get good 4kHz+ chime with a low C cable, and the DCR indicates thin coil wire (assuming they have Steel cores).
BTW, EMG's are not Lo-Z pickups. I also saw an analysis somewhere showing the higher peak of an EMG 81 only in the 2-2.5kHz range, so there's not any more high-end than other high inductance pickups. Maybe some of their other models have higher cutoff points, but you might consider Lace Alumitones if you want really high highs. Not the prettiest pickups, but you can get pretty flat response to 8kHz with A 2H Wilde L90 using a 150~200pF C cable and 250k pots into a 1M input. The Stainless blades don't significantly roll off the highs. It might even be fine in parallel if you want higher highs, but you'd have to ask if they offer it with four conductors.
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Post by antigua on Jan 25, 2022 10:37:21 GMT -5
At least they aren't so high inductance that they can't get good 4kHz+ chime with a low C cable, and the DCR indicates thin coil wire (assuming they have Steel cores). BTW, EMG's are not Lo-Z pickups. I also saw an analysis somewhere showing the higher peak of an EMG 81 only in the 2-2.5kHz range, so there's not any more high-end than other high inductance pickups. Maybe some of their other models have higher cutoff points, but you might consider Lace Alumitones if you want really high highs. Not the prettiest pickups, but you can get pretty flat response to 8kHz with A 2H Wilde L90 using a 150~200pF C cable and 250k pots into a 1M input. The Stainless blades don't significantly roll off the highs. It might even be fine in parallel if you want higher highs, but you'd have to ask if they offer it with four conductors. The circuit up to the point of the coils themselves are low Z, and the coils are not is series, each coil is connected to the op amp, which also lowers the it further. Some say the DCR is 4k per coil, but I don't know, that's probably about right. Just from experiences using both, I think the EMGs are still quieter than passive humbucking alone. I have Lace Alumitones, guitarnuts2.proboards.com/thread/7821/lace-alumitone-analysis-review , but the roll off is less steep, so they sound clearer that a pickup usually would with such a low resonant peak. The "best" pickup for high-highs, I'd say is probably the Burns TriSonics for Strat guitarnuts2.proboards.com/thread/8438/burns-sonic-strat-analysis-review They're kind of like Filter'trons in terms of their EQ, but single coil, and you'd think their output voltage was non existent, but actually they're very useable. They have high eddy currents and a high resonant peak that gives them a peculiar soft knee in the high end. They make a Strat sound almost acoustic-like. |
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Post by gckelloch on Jan 25, 2022 14:13:48 GMT -5
At least they aren't so high inductance that they can't get good 4kHz+ chime with a low C cable, and the DCR indicates thin coil wire (assuming they have Steel cores). BTW, EMG's are not Lo-Z pickups. I also saw an analysis somewhere showing the higher peak of an EMG 81 only in the 2-2.5kHz range, so there's not any more high-end than other high inductance pickups. Maybe some of their other models have higher cutoff points, but you might consider Lace Alumitones if you want really high highs. Not the prettiest pickups, but you can get pretty flat response to 8kHz with A 2H Wilde L90 using a 150~200pF C cable and 250k pots into a 1M input. The Stainless blades don't significantly roll off the highs. It might even be fine in parallel if you want higher highs, but you'd have to ask if they offer it with four conductors. The circuit up to the point of the coils themselves are low Z, and the coils are not is series, each coil is connected to the op amp, which also lowers the it further. Some say the DCR is 4k per coil, but I don't know, that's probably about right. Just from experiences using both, I think the EMGs are still quieter than passive humbucking alone. I have Lace Alumitones, guitarnuts2.proboards.com/thread/7821/lace-alumitone-analysis-review , but the roll off is less steep, so they sound clearer that a pickup usually would with such a low resonant peak. The "best" pickup for high-highs, I'd say is probably the Burns TriSonics for Strat guitarnuts2.proboards.com/thread/8438/burns-sonic-strat-analysis-review They're kind of like Filter'trons in terms of their EQ, but single coil, and you'd think their output voltage was non existent, but actually they're very useable. They have high eddy currents and a high resonant peak that gives them a peculiar soft knee in the high end. They make a Strat sound almost acoustic-like. Yeah, I meant the EMG coils aren't Lo-Z. They may have better hum-canceling than PAF types because PAF types have imbalanced cores, but Wilde L90's are balanced. Even EMG's could potentially have some hum depending on the proximity and angle to the EMI source. Either way, adding another preamp can only add noise. I didn't know the Alumitones were such low Q, but it makes sense. They offer some much lower inductance models that should have better high-end extension, but I actually don't see the advantage for the cost over some of the Wilde pickup options. Your L reading for those Burns TriSonics seems too low. I read they were 1.9H, and the unloaded peak coincides -- assuming a typical internal C. If you want low inductance SC-size HB's, the balanced Wilde L45S is 2H. They have strong lower harmonics like the Micro-Coils, but with a softer/fatter attack character. You could emulate the TriSonic response with a Q-Filter and master tone knob, and get a peak up to ~14kHz with or without a bass reduction. I have that setup on my Parker NiteFly, but with Wilde L280's and an L298SL. I also have a 15nF on the treble bleed so I can get the opposite of the Q-filter sound with one switch and a volume knob turn. It's a great setup. I agree the Q-filter is overpriced, but you know about the alternatives... |
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Post by antigua on Jan 25, 2022 14:39:38 GMT -5
You have to consider that there are two noise types. Hi Z and low Z is arbitrary binaries, where as with impedance and noise, you're talking about a balance of resistance versus capacitive coupling with noise source, and it's really a ratio. The lower the resistance in the circuit, the less capacitive noise you get from elsewhere, so 4k per coil is simply a lot lower than most any passive pickup, and will have lower capacitive noise for that reason alone. I don't know the specs of the L90 but I'm sure they higher than 4k ohms in series, to say nothing of the overall impedance at resonance. Balanced coils are not related to the issue of impedance, as that has to do with magnetic wave interference, the other kind of noise, and humbucking the magnetic wave.
The Strat sized Burns TriSonics are not the same as the full sized ones. I don't think they were intended to have a low inductance, they just ended up being that way. Calling then TriSonics is misleading, so I make sure to mention that they're the Strat sized ones.
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Post by gckelloch on Jan 25, 2022 15:55:37 GMT -5
You have to consider that there are two noise types. Hi Z and low Z is arbitrary binaries, where as with impedance and noise, you're talking about a balance of resistance versus capacitive coupling with noise source, and it's really a ratio. The lower the resistance in the circuit, the less capacitive noise you get from elsewhere, so 4k per coil is simply a lot lower than most any passive pickup, and will have lower capacitive noise for that reason alone. I don't know the specs of the L90 but I'm sure they higher than 4k ohms in series, to say nothing of the overall impedance at resonance. Balanced coils are not related to the issue of impedance, as that has to do with magnetic wave interference, the other kind of noise, and humbucking the magnetic wave. The Strat sized Burns TriSonics are not the same as the full sized ones. I don't think they were intended to have a low inductance, they just ended up being that way. Calling then TriSonics is misleading, so I make sure to mention that they're the Strat sized ones. The 2H L90 or L45S should be under 4k per coil, but they have relatively thin 44~45AWG wire. Is it the DCR or impedance that matters for capacitive noise? The Stainless blades would likely raise coil impedance substantially. What would be a potential source of capacitive noise, and is it really a concern? I suppose you could connect each coil to an onboard preamp and adjust the output of each to minimize noise. |
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Post by antigua on Jan 25, 2022 17:05:31 GMT -5
You have to consider that there are two noise types. Hi Z and low Z is arbitrary binaries, where as with impedance and noise, you're talking about a balance of resistance versus capacitive coupling with noise source, and it's really a ratio. The lower the resistance in the circuit, the less capacitive noise you get from elsewhere, so 4k per coil is simply a lot lower than most any passive pickup, and will have lower capacitive noise for that reason alone. I don't know the specs of the L90 but I'm sure they higher than 4k ohms in series, to say nothing of the overall impedance at resonance. Balanced coils are not related to the issue of impedance, as that has to do with magnetic wave interference, the other kind of noise, and humbucking the magnetic wave. The Strat sized Burns TriSonics are not the same as the full sized ones. I don't think they were intended to have a low inductance, they just ended up being that way. Calling then TriSonics is misleading, so I make sure to mention that they're the Strat sized ones. The 2H L90 or L45S should be under 4k per coil, but they have relatively thin 44~45AWG wire. Is it the DCR or impedance that matters for capacitive noise? The Stainless blades would likely raise coil impedance substantially. What would be a potential source of capacitive noise, and is it really a concern? I suppose you could connect each coil to an onboard preamp and adjust the output of each to minimize noise. The overall impedance matters for noise, because it's AC and so both resistance and reactance are in play. It's still better for that high impedance portion of the circuit to be as short and small as possible, you will get less noise if a higher impedance coil is connected directly into an op amp, and not having to connect with a guitar cable and other lengths of wire. The source of capacitive noise is any electronic device in the area that has oscillating electric charge and is unshielded, because the cycling electric charge will interact with the electrons in the guitar's wiring and create a charge there as well, which manifests and voltage and noise when the electron interaction is on the hot side of the circuit. The idea behind shielding is that the noise source's electric charges will appear on the ground side of your guitar's circuit instead of the hot side. In theory, a perfectly shielded passive guitar should be just as quiet as an active pickup, but I don't think that ever happens in the real world. Actives always just seem quieter to me. The steel blade will increase the inductance, that inductance in turn would just change the frequency at which the impedance maxes out, but that's not too related to the issue of increasing or decreasing noise overall. If the lower peak gives the pickups more mids or more highs, the noise will conform to that same curve. I've often though P-90s were too noisy, but I think it's mostly the lower resonant peak that makes them seem more noisy that a Fender single coil. |
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Post by gckelloch on Jan 25, 2022 18:16:56 GMT -5
Ah, you can see in the SPL graphs of the ~7H GFS P90 I took with and without an 0.08" thick Aluminum pie tin over it that although the noise is reduced by as much as ~12dB in the midrange, it's not reduced at the 3.3kHz resonance peak-- right in the most sensitive human hearing range: drive.google.com/drive/folders/0Bx0CnqsQz_uYblRTLTQwam5FS2s?resourcekey=0-HmA9RFQMWz4AYmvFTPpD2Q&usp=sharingAlthough, the pot resistance and cable capacitance would bring the resonance peak noise down a good bit. Such Alumium shielding would more effectively reduce upper-mid AC noise of lower inductance pickups with peaks above the critical hearing range. Not sure how thick it would have to be to make a significant difference, but you could do a test with a pickup in a guitar. Try taping pieces of 5-10 layers of 0.003" thick Al tape behind the pickup directly across from an AC noise source until you find the number of layers that work for you, and tape them inside the pickup cavities. It may not even need to be grounded if it isn't too close to the pickup coils. Still cheaper and easier than making and installing a preamp. Cu tape would work too, but Al tape is more effective when it's at least ~0.015" thick. |
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Post by antigua on Jan 25, 2022 21:36:51 GMT -5
Ah, you can see in the SPL graphs of the ~7H GFS P90 I took with and without an 0.08" thick Aluminum pie tin over it that although the noise is reduced by as much as ~12dB in the midrange, it's not reduced at the 3.3kHz resonance peak-- right in the most sensitive human hearing range: drive.google.com/drive/folders/0Bx0CnqsQz_uYblRTLTQwam5FS2s?resourcekey=0-HmA9RFQMWz4AYmvFTPpD2Q&usp=sharingAlthough, the pot resistance and cable capacitance would bring the resonance peak noise down a good bit. Such Alumium shielding would more effectively reduce upper-mid AC noise of lower inductance pickups with peaks above the critical hearing range. Not sure how thick it would have to be to make a significant difference, but you could do a test with a pickup in a guitar. Try taping pieces of 5-10 layers of 0.003" thick Al tape behind the pickup directly across from an AC noise source until you find the number of layers that work for you, and tape them inside the pickup cavities. It may not even need to be grounded if it isn't too close to the pickup coils. Still cheaper and easier than making and installing a preamp. Cu tape would work too, but Al tape is more effective when it's at least ~0.015" thick. For capacitive noise, which shielding and low impedance address, the shielding layer could be very thin, just thick enough to have negligible resistance. For magnetic noise, it would have to be a few inches thick, because the magnetic wave would be repelled by Lenz's law, basically eddy currents, but just a little bit, per thickness and frequency. The guitar string is also a magnetic wave, so that sort of shielding also blocks out the guitar string. I've done lots of eddy current testing, as has Ken Wilmott. The best kind of pickup shielding is the kind that has cuts in it that disrupt eddy currents, like the H pattern in a Filter'trons cover. Thicker isn't better in that case, it just causes more loss of treble. When it comes to eddy currents, depth matters, and the higher the frequency, the more shallow the depth, so if a pickup cover were very thick, it would not only cost treble, but also mids, and then eventually lows. The way a magnetic shield would work is that it would have to be so thick that eddy currents would wipe out waves of frequencies below the frequency of the noise. It's not practical to do that, it's just a thought experiment. |
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Post by roadtonever on Feb 5, 2022 13:00:21 GMT -5
What would you rank as the top few mods to make it perform like the real deal? My guess is according to this analysis the coils are connected in parallel but the reistance and inductance effectively matching that of a coil split. In other words it's as if both coils were buffered independently. That should be a pretty simple circuit to build. Active blending preamps are in fact fairly popular for bass guitars(only with more functions and parts). |
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Post by antigua on Feb 5, 2022 14:18:08 GMT -5
What would you rank as the top few mods to make it perform like the real deal? My guess is according to this analysis the coils are connected in parallel but the reistance and inductance effectively matching that of a coil split. In other words it's as if both coils were buffered independently. That should be a pretty simple circuit to build. Active blending preamps are in fact fairly popular for bass guitars(only with more functions and parts). Mod the pickups or the whole guitar? For the pickups, there's no way to wire them parallel, they're hardwired in series and gooped in epoxy. It's an interesting question what the effective difference is between an EMG and a passive pickup wired into an onboard pre-amp, maybe wired in parallel in order match the EMG's impedance more closely, and then EQ'd to have more mid-range. Not a whole lot of difference, in theory. Sometimes more physical distance in a circuit increases noise potential, but in other cases it causes it to decrease. As for these guitars, the frets are the main issue. It appears to me that they don't actually file and polish the frets, they just have them pre-cut, and then they press them into the neck with some sort of jig that makes it flat, but it doesn't work out perfectly and some of the frets are popping up off the fret board, meaning the action has to be somewhat high in order to clear the bad frets. I've pulled those frets out and fixed them one by one, and it has made the guitars play better. In some cases there is slight neck warpage, some speculate because they don't let the wood age and settle before making neck out of it, so it continues to shrink or expand unevenly after being created. In that case, the guitar may never play "well", but other times a fret job can allow even frets to compensate for an uneven fret board. They're definitely project guitars, they all need attention of one sort or another. |
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