|
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!
|
|
|
Post by Charlie Honkmeister on Feb 16, 2017 10:30:27 GMT -5
Along these lines, I saw someone tape a length of guitar string to a speaker and then place it over a pickup. Not bad, but the string is not in situ. I wouldn't have thought it mattered until I saw such variation between bridge, middle and neck positions. The way a pickup relates to the strings seems to differ in the bridge versus the neck, it's not a linear thing. For example, a humbucker bridge will be louder than a single coil bridge because the humbucker reaches out towards the neck, but this "handicap" doesn't exist for the neck position, where both types of pickups are more or less on equal ground (save for the neck anti node). Complicating matters even more, if the pickup has a coil that is close to the top of the pickup (Lace Sensor), this bridge/neck disparity appears to be magnified. For my purposes, all I really need are ball park figures, because if two pickups are within, say 3dB, you can close that gap by just adjusting the heights of the pickups a little. What's important are conditions that represent huge differences, such as three more henrys of inductance, or two side by side coils instead of one. For relative levels within 3 db, I think you could just use careful measurements made with your small exciter coil. And having made all these measurements, I think you have the data to show that, or to find out what needs to be done in order to make it work. After thinking about this a little bit, I would side with ms on this, in that the output of a pickup is a "secondary" measurement and is not as important as the other things you want to measure. If you had the task of reverse engineering a pickup without destroying it, IMHO you would have the core information you need just by running your (or ms's, or both) suite of tests, without needing any output measurement referenced to some standard. The only pieces of data that would be immediately useful numbers if you were trying the reverse engineering thing, would be the wind count on the coils, and the AWG of the wire. But since we are playing in a relatively small sandbox (almost always #41 to #44 AWG, known overall geometry, etc.) there's ways to either directly infer the wind count (inductance, DCR proportional to number of winds for a given AWG, using Salvarsan's coil calculator), or nondestructively inspect the coil wire, to get the AWG. So the electrical measurements other than absolute output are really the key and you guys have gotten that covered really well. If we were doing a "fundamental physics" investigation, we would be chasing off after magnetic core materials, temperature effects, and all that stuff. But you guys (Antigua, ms, JohnH) have absolutely nailed the right set of methods and theoretical/practical balance to be the most useful, as things stand now.
|
|
|
Post by Charlie Honkmeister on Feb 14, 2017 23:32:23 GMT -5
Thanks for some great persistent work here, Antigua.
Do you want to pursue any greater consistency on the "strum" or string excitation, or do you think that most folks will need anything more accurate than what you have done?
If you wanted to chase any more consistency, would you think that you would need a mechanical plucker (which would be not that hard to do with group help, with steppers or radio control type servos and some sort of 3D printed armature)? I could really see whipping something up with an Arduino and a stepper.
Or would you be thinking you would go back to refining the driver coil measurement where you might standardize your driver coil (geometry, winds, etc.), drive voltage, power, and input signal (pink noise maybe, or ms's sequences) and standardize the position and height in both single coil and humbucker measuring modes?
Just curious where you might want to go next or whether you even want to at this point.
-Charlie
|
|
|
Post by Charlie Honkmeister on Feb 7, 2017 17:08:39 GMT -5
|
|
|
Post by Charlie Honkmeister on Feb 6, 2017 16:29:14 GMT -5
Here's some reference information on the quick connect plugs and wiring that Gibson uses on their guitars with a circuit board in the control cavity. Thanks to the original contributors for this information. Connectors:
Original Post: music-electronics-forum.com/t39998/ I think the brand is Molex. oops Tyco.. www.mouser.com/ProductDetail/...8IEbI6SHc3Q%3d After taking a second look, those look like PC motherboard connectors. Maybe find an adapter for USB and splice to it. Here they are... www.mouser.com/ProductDetail/...VMHMAK5Q%3d%3d Terminals.. www.mouser.com/ProductDetail/...U0wF54cENGw%3d Those are 4 pin connectors, Gibsons are 5 pins, just change the suffix to 0500 from 0400. Last edited by guitician; 07-25-2015 at 07:28 PM. Wiring Color Code:Original Post: guitaristguild.com/index.php?topic=437.0Hey Gang. I recently found an issue when trying to install a new set of Gibson 490R/498T pickups into a 2013 Gibson Les Paul LPJ. The LPJ has the new quick connect board and connectors. The problem was the new standard pickups did not come with quick connect connectors so I assumed you can just splice them to the existing pigtail and all would be fine. NOT SO. You can connect them in this manner and both pickups work but the middle switch position has "noticeable" power loss. Here's what I found... Gibson changed the color coding on the connector for the Bridge pickup and that caused the pickups to be out of phase when installed properly (color to color). Here's the details... Standard Gibson pickups with 4 conductor capabilities have 5 conductors (including screen or shield). They are manufactured with this coding... Red - Hot or +ve White - upper coil finish ( connects to green in 2 conductor installs) Green - lower coil finish (connects to white in 2 conductor installs) Black - Ground or -ve Shield - Connect to black or ground I was installing standard Gibson 490R/498T's which do not have quick connect connectors. Now here's where it gets good. The quick connect board and connector have these color codings... Neck - Pin 1 - Shield / Pin 2 - Black / Pin 3 - Red / Pin 4 - Green / Pin 5 - White Bridge - Pin 1 - Shield / Pin 2 - Green / Pin 3 - White / Pin 4 - Black / Pin 5 - Red (I'll to add some pics in this post) So the neck circuit is looking for Red/Black as the positive and negative and the bridge is looking for White/Green. (Note: This is the circuit for both of my 2013 LPJ's and a friends 2013 Studio with the same pups and QC board) So when I hooked up the pickups to the quick connect pigtails and observed proper color coding it actually put the pickups out of phase. To rectify you have to forget about connecting proper colors to proper color and just give the board what it is looking for... Again note... this is only for the Bridge... the Neck is color coded properly. For the bridge pigtail... Connect Red from pickup to White on pigtail Black from pickup to Green White from pickup to Red Green from pickup to Black Shield to shield If you do not connect it like this, it will still work but there will be a noticeable power loss in the mid because of out of phase. This can be verified with clip leads if you are skeptical. (NOTE: If you have a different color coded pickup then just hook it up following your coding to the pigtail inputs above.) Hope this helps someone and saves them time and troubleshooting. Mike@Ferro-Kings
|
|
|
Post by Charlie Honkmeister on Feb 5, 2017 16:48:52 GMT -5
Mike, can you run both impedance and gain tests with, say, JohnH's, stratotarts and antigua's standard load of 200K ohms and 470 pF, and have both tests work computationally? I apologize if I missed any dicussion on this previously.
I'm curious to see if for the frequency range of interest in current passive instruments, basically 6 KHz and below, how the eddy current loss results jibe with JohnH's measurement methodology and parametrization of modeling data. I think they are leading to the same place, based on JohnH's reworking of some of his data into real and imaginary plots.
It is good to have both modeling and measurement, and from there we can not only characterize existing magnetic pickups, but also have a means of guiding new design and evaluating new designs against old.
|
|
|
Post by Charlie Honkmeister on Feb 4, 2017 22:19:30 GMT -5
I'll bet they will, too. There's always been attempts to lower the resonant peaks of Fender type single coils, to make the distortion sound "better" or less "weedy." Bill Lawrence stated some years back that his first hand knowledge was that the "secret" to the "pickup" part of Jimi Hendrix's unique Strat tone (e.g. "Purple Haze") was an extra long, extra crappy (high capacitance) cable which would shift the pickup resonant peaks down closer to 2K or so. Jimi would also reportedly switch to a shorter, "better" cable for cleaner sounds in the studio. That's amazing though, that Fender would put a 4 Henry single coil pickup in a Strat. That's in the territory where you could put in a parallel inductance a la Lawrence Q-Filter, and still have enough output in "clean sound" mode. But why you wouldn't use a humbucking pickup when you are in that inductance range, for noise reasons, is beyond me. All true. The Mexican Fender singles achieve 4H in part due to their steel cores, but the DC resistance of 7k shows that they deliberately applied a lot of wire. Another example of forcing hot pickups on consumers are Epiphone versus Gibson Les Pauls. In the low cost Epiphone Les Paul they used to install "AlNiCo Classics" where you have a hot bridge measuring, it's is said, up to 13k, and 8.5k for the neck, while on an actual Gibson Les Paul they install "57 Classics" which come in around 8k for the neck and bridge alike. Apparently they got the clue that people did not want hot pickups installed stock, and more recent Epiphones comes with "Probuckers", which are lower wound than the "AlNiCo Classics". I'm totally dialed in on lower wind or "vintage" sound pickups for a number of reasons, not the least of which is that a 4-wire humbucker of about 8K to 8.5K DCR and 4 to 5 Henry in series coil mode, can be put into parallel coil mode and with either my variable cap/buffer approach, or just modeling and picking the right passive components, mainly capacitance, can be capable of Fendery sounds with a resonant peak around 3.8 to 4.2 KHz. What I'm seeing is sort of a consensus with a "vintage PAF" neck coming in at about 7.5 K DCR, and a bridge in the set coming in at 8.2K to 8.5K or so. The Seymour Duncan set that most fits that description is the Pearly Gates set, which is supposedly meant to sound like Billy Gibbons' '59 Les Paul. Epiphone has really stepped up their game with the ProBuckers, and rumor has it that the new lower cost Gibson guitars have Gibson label pickups built in the same China factory, probably with darn near or identical construction to the Epis.
|
|
|
Post by Charlie Honkmeister on Feb 4, 2017 11:38:42 GMT -5
Mike,
You should think about doing an AES paper on your measurement methodology. I, for one, really appreciate your theoretical insight and persistence.
I do want to point out that it's at least possible that the ESR of the 470 uF electrolytic capacitor might be enough at higher frequencies (say, 10-20 Khz) to slightly change the very low AC impedance to ground of the bottom end of the pickup in your buffer.
Since you went to a lot of trouble to get a completely "neutral" buffer, and you are measuring some pretty subtle eddy effects, it wouldn't be a bad idea to bypass the 470 uF with a .1 to .22 uF polyester film (good) , polypropylene or polystyrene (best) film capacitor, to make sure that you have a darn good "AC ground" for the pickup in your measurements.
Probably no difference, but maybe best to eliminate or minimize any possible sources of inaccuracy for these measurements.
For really critical circuits, I just don't trust imported bulk electrolytic capacitors (they almost all are these days) any more, for leakage and ESR.
-Charlie
|
|
|
Post by Charlie Honkmeister on Feb 2, 2017 23:02:45 GMT -5
Thanks very much for the diagrams! Appreciate the clear drawings of some of the variations that are possible.
|
|
|
Post by Charlie Honkmeister on Feb 2, 2017 15:48:44 GMT -5
OK, thanks, got it. Since we are used to seeing pickup color codes , start/end wires, etc., it was a bit confusing.
|
|
|
Post by Charlie Honkmeister on Feb 2, 2017 10:27:30 GMT -5
Ummmm.... excuse me reTrEaD , but wouldn't your series/parallel switching diagrams be incorrect for a humbucker, since the coils are going to be in phase, and because they are in phase but working with different magnetic polarities, will mostly cancel the string signal, and not cancel the hum? Series link humbucker: two winding starts together for series link, or two winding ends together. Electrically out of phase in series. Magnetically in phase for string signal. Parallel link humbucker: winding start of one coil to winding end of the other coil, x2. Electrically out of phase in parallel. Magnetically in phase for string signal. Check the drawing below to see what's happening with the starts and ends of the coil windings.
|
|
|
Post by Charlie Honkmeister on Jan 23, 2017 23:48:48 GMT -5
I can't say I agree. I think that those ridiculously over-wound pickups such as the SDS-1, Super D, JB and SSL-5 et el were an 80's thing. Now you see people going for Seth Lovers on the PAF side, or Lollar Blackfaces on the boutique side. Kids of the past might have been planning to cover Metallica, but I think guitars are appealing to a different demographic these days. Besides that, amps offer too much gain anymore, you don't have top push no front ends. Yes, people want "sweet highs", but even more, they don't want muddy chords. The boutique market owes Fender and Gibson a debt of gratitude for putting trashy pickups in their import lines. The verbiage they use, note separation, articulation, clarity, chime, jangle, are all qualities that track with a lower wound pickup, they've used this sales pitch to sell $300 pickup sets to teenagers for years, decades even. All I say for sure is that these hot stock pickups, the Fender Mexico and and Epiphone, have had a bad reputation in the community, while the Probucker's on Gibson's side, and the Tonerider AlNiCo OEMs in the Fender Vintage Vibe have received praise. Certainly there is an increased reverence for the past, but then you have to get rid of the high frequencies in order to get the sound you need. There is a reason why the boutique winders introduced the hot pickups way back when when Fender and Gibson still thought that people wanted good high frequencies for playing clean. (Look at some of those old Fender ads with short haired clean cut guys in tuxes smiling happily as they play their strats.) I still sometimes read of how that guy on the Eastern shore of Maryland who makes those really good expensive guitars cannot make a decent pickup. No, he just knows what his clientele needs. For versatility in a single instrument, you really want "all of the above." Both ways of looking at hot pickups are valid depending on which musical style you're going after. I've always thought and heard from others, that there are three fuzzy classes that you can roughly put guitar tones - clean, crunch (light to moderate distortion) , and heavy distortion. You can even see this kind of partitioning on amp channels, stompboxes, etc. The highs you need and the EQ you need in the electric signal chain are different for each class of sounds to get the best range of tonality within a class. So you guys (ms and Antigua) are talking about two different classes of guitar sounds. You're both right. Any given passive pickup instrument without "help" (onboard or offboard) in general, is going to be compromised for the best tones in at least one of the three tone classes. One prime motivation for doing what I'm doing now is to see if it's possible to have a single instrument that is capable of versatile enough tonality to not only be OK, but really good at all three classes. I'm pursuing the "clean" alternative even to the degree that I'm testing my buffered instruments with a "flat" acoustic amp, and making sure that the highs at 6-8Khz sound good, even though I know that lots of those highs will be "wasted" on a typical guitar amp which starts rolling off at 5 KHz. For crunch to heavy distortion, you need the resonant peak lower in frequency and roll off high harmonics sooner. But I have to get the clean sound right first.
|
|
|
Post by Charlie Honkmeister on Jan 23, 2017 14:21:08 GMT -5
All true. The Mexican Fender singles achieve 4H in part due to their steel cores, but the DC resistance of 7k shows that they deliberately applied a lot of wire. Another example of forcing hot pickups on consumers are Epiphone versus Gibson Les Pauls. In the low cost Epiphone Les Paul they used to install "AlNiCo Classics" where you have a hot bridge measuring, it's is said, up to 13k, and 8.5k for the neck, while on an actual Gibson Les Paul they install "57 Classics" which come in around 8k for the neck and bridge alike. Apparently they got the clue that people did not want hot pickups installed stock, and more recent Epiphones comes with "Probuckers", which are lower wound than the "AlNiCo Classics". I think people mostly do want hot pickups (that is, high level with increased overdrive capability, reduced high frequencies, and lower levels of resulting high order intermod distortion) because distortion is mostly what rock guitar playing is about, but it cannot be too harsh. Let's see, is this the exact 50th anniversary of the recording of Purple Haze? Not quite, but close. Where did those high frequencies from the strat go? How about a low impedance input fuzz face using a low beta germanium transistor? (In that case the cable would make little difference.) But wherever they went they were really gone and replaced by harmonics and intermods from the first few guitar harmonics. What happens when you give a couple of power blue strats to some guys used to playing with much less lively guitars? You get Nowhere Man. Yep, some good points, Mike. The "hot" pickup isn't just for higher signal level pushing an amp, but also rolling off higher harmonics that would intermod and clash when the signal is distorted. That reminds me also of why only octaves and fifth chords (power chords) using only a couple or three strings sound OK under heavy distortion - it's the same reason. There are supposedly some pickups that can sound good both clean and distorted. I wonder, if those beasts exist, could we apply the modeling and analysis tools and find out why?
|
|
|
Post by Charlie Honkmeister on Jan 23, 2017 13:53:27 GMT -5
All true. The Mexican Fender singles achieve 4H in part due to their steel cores, but the DC resistance of 7k shows that they deliberately applied a lot of wire. Another example of forcing hot pickups on consumers are Epiphone versus Gibson Les Pauls. In the low cost Epiphone Les Paul they used to install "AlNiCo Classics" where you have a hot bridge measuring, it's is said, up to 13k, and 8.5k for the neck, while on an actual Gibson Les Paul they install "57 Classics" which come in around 8k for the neck and bridge alike. Apparently they got the clue that people did not want hot pickups installed stock, and more recent Epiphones comes with "Probuckers", which are lower wound than the "AlNiCo Classics". Yes, I actually had a bit of trouble trying to find inexpensive test bridge humbuckers that were about 8K DCR and about 4 to 5 H. So many of them are 12K to 16K DCR. That's why I went to rails for the first two instruments - so that I could get a "neck" wind of about 8K, use the same PU for the bridge, and not have to worry about 50mm versus 52mm polepiece spacing. I have absolutely no use for a "hot" bridge pickup because I'm trying to get Fendery sounds out of the pickup , and I need from 1 to about 1.5 Henry in parallel coil mode for that. Standard "vintage" wind PAF clones are right in the ball park as long as they're 4 wire. From there you can go down in resonant frequency with capacitance and get traditional Gibson HB flavors, bright to dark. Keeping the Q down with resistive loading so that the resonant peaks are anywhere from 6 to 7.5 dB over the tuneable range, gives very good tonality at both ends - it looks like you don't have to dynamically vary the Q to go from Gibson-y to Fender-y.
|
|
|
Post by Charlie Honkmeister on Jan 23, 2017 9:27:23 GMT -5
It's pretty subjective for the most part, so I don't blame them with going for the "average" pickup with a known name brand on the face. What bothers me more is that I've seen a lot of "hot" pickups come stock, as if we're all heavy metal shredders. All of the Zemaitii I've bought to date have come with fiery hot humbuckers and single coils. I know Ronnie Wood played a Zemaitis once, but we're not all trying to be Ronnie Wood. Then I just measured the pickups out of a Fender Mexico Strat made this year, over 4H inductance and 7.0k DC resistance per pickup. I imagine the loaded resonant peaks are going to land in humbucker territory. I'll bet they will, too. There's always been attempts to lower the resonant peaks of Fender type single coils, to make the distortion sound "better" or less "weedy." Bill Lawrence stated some years back that his first hand knowledge was that the "secret" to the "pickup" part of Jimi Hendrix's unique Strat tone (e.g. "Purple Haze") was an extra long, extra crappy (high capacitance) cable which would shift the pickup resonant peaks down closer to 2K or so. Jimi would also reportedly switch to a shorter, "better" cable for cleaner sounds in the studio. That's amazing though, that Fender would put a 4 Henry single coil pickup in a Strat. That's in the territory where you could put in a parallel inductance a la Lawrence Q-Filter, and still have enough output in "clean sound" mode. But why you wouldn't use a humbucking pickup when you are in that inductance range, for noise reasons, is beyond me.
|
|
|
Post by Charlie Honkmeister on Jan 22, 2017 23:28:36 GMT -5
LOL Antigua, I have called some of the vintage and custom guitar folks "cork-sniffers" for a while now. And Winter NAMM is just winding up which has a lot of folks/companies catering to that market.
It always gets me how custom builders will create wondrous works of art and skill , hundreds of hours of work into a wonderful, playable physical instrument, and then just slap a set of Duncans, Lollars, etc. with a completely standard type set of tone and volume controls (albeit maybe expensive pots and caps), and call it a day for the electric tone of the instrument, it seems. They won't even check tolerance on the pots and caps and hand-pick to get better values and avoid the results of tolerance stack-up.
Yes it will probably sound OK to good, but if a small bit of time were put into engineering and voicing the electric tone instead of blindly repeating a 60 year old set of formulas, I can't help but think that the results would be better and more satisfying for the buyer/end user. Otherwise it's chasing magic rabbits from hat to hat and/or trying to convince the buyer that the rabbit is in the hat that you are selling.
|
|
|
Post by Charlie Honkmeister on Jan 21, 2017 20:38:48 GMT -5
Yeah there are at least two potential uses for the modelling, 1) to see how a pickup or wiring scheme will work out before you implement it, or 2) the demonstrate correlation between the real and the theoretical, and you still have a value proposition with capacity #1 even if you were to completely neglect #2. There's a third use that might be interesting - that is, emulating a given known pickup response (to a "good enough for rock 'n' roll" level or better) by changing external component values (mainly, load C and R) of another measured pickup with a higher native self-resonant frequency and Q. That's really the "thang" I'm pursuing right now to increase the tonal versatility of the instrument. So, it's "tone engineering" where you can craft the pickup response the way you wish for a particular instrument or music style. I suppose though, that that's a more targeted restatement of Antigua's use case #1 above. With this thread, I'm being struck with the point that thanks to you guys, all the pieces are in place for a full "engineering loop." Modeling/simulation, real world measurement, understanding the effect of the various components, and getting repeatable, predictable results. Antigua, JohnH, ms, stratotarts and a couple of others --- you guys with your work and postings have just about written the definitive book on "Guitar Tone Engineering 101" as well as provided or assembled the tools and methodology. This is crazy good stuff and I'm sure I'm not the only one who vastly appreciates it. -Charlie
|
|
|
Post by Charlie Honkmeister on Jan 18, 2017 1:36:57 GMT -5
China Girl and Redbird First instruments with pre-production variable res tone system using my from-scratch design. (circuit design, PCB layout, SMT PCB, assembly) I've just finished up with these two guitars. Generally for my first demo instruments I am taking inexpensive guitars or factory seconds and fixing/repairing them, then completely gutting the electronics and installing my variable res tone system. I will be working soon with a couple of local builders to try to move up the guitar food chain. China Girl (in memoriam David Bowie) is a Drive Wildfire X3: Gibson scale length, set neck, maple over mahogany, Guitar Madness (believe Artec) rail humbuckers (about $14.00 each.) Strung with Dunlop 10's. Redbird is a Parker PDF70 (Indonesian): Fender scale length, ebony board, Parker tremolo, SOS compensated nut, CALIG H62 rail humbuckers (about $22.00 each.) Strung with D'Addario 9.5-44 which are my favorite on a Fender scale length. I had to do a little bit of spot leveling fretwork on both, and on Redbird, had to clean up the fret ends. Both got a fingerboard reconditioning, fret polish to 8000 grit, and complete setup. China Girl has a push-pull which switches the guitar into "studio mode" when pulled. That just converts the tone to a simple variable lowpass and also allows the guitar to be set "flat" if wanted , for going into a board or computer running a DAW with plugins. Redbird has a push-pull which when pulled switches the bridge pickup into series coil mode. This gives a volume boost and moves the tone control range down to allow the player to get a quick lead boost for a crunch or distorted solo. Both instruments can cover tones from dark Gibson humbucker jazz tones (think vintage ES175, but more clarity on the high end) to bright, spanky Fender cleans a la Tele but without icepickiness, and everything in between. It's a bit of a minor mindblower to hear Fender-type tones coming from a two-humbucker guitar. These went through about three rounds each of listening and tweaking to dial in the right component values. Since the key resistors and capacitors are on an 8 pin DIP component header plugged into a DIP socket on the board, tweaking values just involves opening the control cavity, popping out the header, soldering new parts to the header, and plugging the header back in. It takes about 5 minutes for any component changes needed to tweak the voicing. I'm also compensating pickup load resistance based on one pickup or two in parallel, but that's done at the pickup selector switch and/or the series/parallel push-pull. This can provide a near-acoustic sound quality when the selector switch is in the middle position. Both of these instruments sound amazing now that the resonant frequency ranges and Q values have been dialed in. -Charlie
|
|
|
Post by Charlie Honkmeister on Jan 14, 2017 13:25:16 GMT -5
A simple "Thank you" doesn't seem to be nearly enough. Finally, good measurements made with a consistent known methodology. Great HTML job in being able to not only display, but sort and search as well.
Are you interested in having the group members send you more pickups to test over time?
|
|
|
Post by Charlie Honkmeister on Jan 14, 2017 2:44:02 GMT -5
BTW all of the wiring mods/switching arrangements we have all tried over the years should still be valid with this approach but I prefer to use volume controls after the buffer and, I have no (or vary little) use for passive tone controls as a pot, any more after doing this and hearing the results. -Charlie In all of my homemade guitars instead of a regular tone control I implemented what I call 'fatness' control, which is all passive. My passive circuit uses a large-value inductor of 1H (that is not a typo) in conjunction with a capacitor and forms a tank circuit to scoop out the mids to a variable extent depending on the rotation of the knob. I simulated it using old-fashioned SPICE many years ago. It allows the guitar tone to be 'thinned' but still preserve the clarity of the attack, and as a result it totally changes the character of the pickup (makes the bridge pick become more 'gentle' than the neck pickup when set to the lowest 'fatness' level). I have never yet used it on the bridge pickup - since those large-value inductors were expensive components - but I might try swapping the bridge and neck tone controls sometime to see how it sounds. Mixing pickups with this control in place adds another dimension to the variety of tone settings it can achieve, and I am still discovering new ways to set it that I never tried before. I was never comfortable with using batteries in my guitars, so my goal was to arrive at a passive tone control solution that would have a stronger effect than conventional controls do. IMHO my design achieved that. Ever since I bought the Torres passive midrange control a number of years (>10) ago, and discovered that it used (as well as RC networks and a pot) an inexpensive miniature transformer to provide about a 1 H (I think) inductor, I've been fascinated with using passives to modify tone as well. Not everyone understands how nicely a passive midrange, or a Bill Lawrence Q-Filter, can help you re-voice the instrument and allow you to get beautiful clean, almost acoustic at times, sound. What worked best for me pickup-wise, was to get a hot (say, 10-15K ohms DCR) but not too hot (>15K DCR ) pickup to work with the passive midrange/LCR/Q-filter. I'm definitely digging my current active approach but most of the great recorded guitar sounds were made with passive instruments. I'm sure I and a lot of other players will always have one or more in the corral. Just agreeing from experience with what Antigua has been saying here in the thread, If you have a good LCR meter (Extech or DE-5000 or better), and an EDA tool like LTSpice or Circuitlab, you can very easily (albeit a bit draggy at times,) nail down component values with simulation to make a passive solution work well. You can save umpteen times the hours over the strategy of just messing with things until they sound good. Again, many, many thanks to Antigua for taking the time to actually do an illustrated LTSpice tutorial. (I'm so proud of myself. I steered back on topic. )
|
|
|
Post by Charlie Honkmeister on Jan 11, 2017 21:52:02 GMT -5
Apologies for diverting the thread, guys.
|
|
|
Post by Charlie Honkmeister on Jan 6, 2017 13:44:37 GMT -5
So, in general, would it be fair to say that you need enough of inductance increase in the bridge in order make the fundamental 6dB to 8dB greater? It might be useful to some pickup winders out there (who appreciate this sort of thing) to have a calculator or a table that answers the question: if my neck pickup, and perhaps middle pickup, are inductance X, then what inductance is needed to make the bridge pickup roughly as loud at the fundamentals, to the nearest extent it can be approximated? Only problem with that is, that if you want to maintain the "same" tonality and increase the inductance to get more output for the bridge, you also have to decrease the capacitive part of the RC load, on a per-pickup basis. This is surely doable, but is starting to argue for onboard buffering the instrument, and then doing anything we want for RC loading, including custom loading per pickup, before the high-Z buffer, and getting rid of dependency on cable capacitance.
|
|
|
Post by Charlie Honkmeister on Jan 6, 2017 13:29:46 GMT -5
And it quacks like a duck on crystal meth.
|
|
|
Post by Charlie Honkmeister on Jan 6, 2017 12:42:39 GMT -5
(deleted) If I understood correctly, if, for example, I had a Strat and I were in the classical situation where I wanted that growly PAF tone at the bridge, but without going for a HSS pickguard, this thread should suggest that I definitely wouldn't find that exact tone if I only chose a single coil bridge pickup with the same resonant peak of that humbucker. It wouldn't be the same thing as installing a real PAF there, I mean, because of the different harmonics sensing. Now, I don't know how that angled bridge single coil translates as far as harmonics sensing, but I guess that's still different from a full size humbucker, because of the lack of comb filtering and narrow geometry of the single coil, isn't it? It is, but if you are talking about a full sized humbucker type loaded resonant frequency, a lot of the harmonic content differences are irrelevant because they are buried in the weeds above 3 KHz or so, because of the steep rolloff above resonance. Single coil sized bridge humbuckers can be very successful in a Strat. I remember the first one I put into a Strat -- a Seymour Duncan JB Junior. It had a really great lead voice under crunch and distortion - humbucker growl with just a little bit of squawk. Not identical to a Gibson Les Paul bridge HB crunch (your point) but hot, fluid, and expressive. The only problem (common) is that you could never get it to sound really "Strat single coil-like" either split or parallel coil, and as a result, in the notch position 2, the "quack" didn't sound right for cleaner playing in either HB or single coil mode, although it was fairly close with some height adjustments. Some folks on Harmony Central back in about 2002 or so were saying that the DiMarzio Fast Track 1 had a good single coil voice when split and good distortion tone when in HB series mode. Not to overly toot my own horn, but the variable resonant frequency tone control I have been working on was put in a Strat for the first demo. The bridge PU resonant frequency can be dialed from about 1.5 Khz to about 5 KHz - good HB midrange sound at one end of the pot, to super bright Strat/Tele sound at the other end of the control. I've written a post where you can duplicate this with just off the shelf parts including a commercial buffer module, and cheap Ebay Chinese single coil sized humbucker rail pickups that go for about $8.50 each.
|
|
|
Post by Charlie Honkmeister on Jan 5, 2017 0:40:43 GMT -5
BTW the 750K was just a finger in the wind estimate. You may be able to experiment with the value from 500K to 2 Megs, and find something that works. A metal film resistor assortment is pretty cheap on Ebay.
I completely agree with you about not changing the pickups for now.
If the resistor doesn't do the trick, you might be able to move the resonant peak (assuming that's the issue) down in frequency with a capacitor, but this might create a tradeoff with the split coil sound. But it might be worth pursuing and this forum is a good place to get help pursuing it.
|
|
|
Post by Charlie Honkmeister on Jan 5, 2017 0:34:21 GMT -5
Hey All, First up a bit of history on the guitar, it a PRS SE Standard 24, purchased new from Sweetwater in November of 2015 (birthday present to myself, and just what I wanted too!). Lovely Tobacco Sunburst finish and a really nice player to boot, at least I like it. My only complaint is that is can be a bit shrill, or maybe a bit to bright really more than shrill. So, I was talking to a guy at the local Guitar Center and he mentioned he had changed the string saddles to the Graphtech string savers. Then another guy there said the pickups in those are crap and to change them (by the way, I'm not really buying this one one, because when split to single coil mode they just sound way to sweet). OK, so in checking the Graphtech stuff out I was reading on their website about this 2K spike that can be inherent to cast metal string saddles. This makes me wonder if this will indeed sweeten up the tone of this instrument. So, here's my two part question for all you gear heads; Have any of you out there made this change to this or a similar guitar? And, would you recommend changing out the nut as well? (I'm considering a Ghaphtech Tusq nut as well) Just looking to pick the brains of a few that may know better/more on the subject. teking66, I have a PRS SE Standard 24 in red, and it's a great instrument; congrats on your good taste I have String Saver saddles on one (formerly two) other axe, but it is/was a Tuneomatic, not the individual saddles. You have to take the Graph Tech info about the 2K spike with a grain of salt; it's possible that they measured that on a Tuneomatic and not on individual saddles such as Strat and PRS. That being said, the String Savers are really good, but they do sound a tiny bit different. It might not be the "different" you need for your situation. If you want to darken the tone a little bit and can solder, you might want to try soldering a 750K ohms, 1/8 watt resistor to the outside 2 lugs of your volume pot. Assuming 500K pots, which is usually safe assumption for humbuckers, this should bring the resonant peak of the pickups down and very slightly darken the tone. Coil split mode won't be affected as much as normal humbucker mode. If this doesn't help you you could consider the Graph Tech parts depending on your willingness to spend some money, but the resistor is cheap and worth a try. -Charlie
|
|
|
Post by Charlie Honkmeister on Jan 4, 2017 23:51:19 GMT -5
It's such a pleasure to have detailed data to compare, to see a point somebody's making. Yes, your plots absolutely confirm the effects of eddies that I first read about in Lemme's article. Also hats off to Ken (stratotarts) for his very interesting and well-researched data and experiments on eddies in pickup covers. About all I can say at this point is that I'm going to go forward with the Mojotone rails build and given that it doesn't have a metal baseplate or a cover, it should be at least "pretty good" on eddy effects. I'm going to shoot for hi-fi clarity to start with, and see where that goes sound-wise. I have a Syscomp CGM-101, driver coil, DE-5000 LCR meter, etc. so at least in theory I can do the same sorts of measurements if need be. I will ask stratotarts about an integrator; was thinking about doing it in software but the integrator will allow better dynamic range methinks. Thanks so much for your responses, guys. Will update this thread as things progress. -Charlie
|
|
|
Post by Charlie Honkmeister on Jan 4, 2017 19:19:56 GMT -5
The rule of thumb target inductance for doing the whiz-bang variable resonant frequency things, is about 1 Henry give or take about .2 H. The idea on using less metal is to reduce eddy current loss to a minimum, so the pickup by itself is more "neutral". Output isn't necessarily the biggest thing to optimize. What we're trying to go for is a "baseline" good large humbucker design with decent output which we can voice any way we want to. What I have so far which is working well with the buffer design is approximately: 1 to 1.2 Henry inductance 1.9 to 2.2 K DCR 110-220 pF capacitance (measured with LCR meter, end of the cable, windings to ground. Not calculated from resonance so is probably off) In parallel coil mode, these inexpensive ($8.50 or so) Strat-sized humbucker pickups hit these numbers and are self-resonant at about 10 KHz : Just trying to get a full-sized humbucker solution in the same range. Antigua, I am not completely sold on rails, but since without doing a lot of rwinding, I have to use neck humbuckers with 50 mm pole spacing. I will try to get some of the bridge PU's I have rewound for lower inductance, and will absolutely have a low-wind conventional looking set which I can point to and say that it works with the variable voicing. Very good point about conventional looks. But rail PU's do look great IMHO on a Strat or Tele.
|
|
|
Post by Charlie Honkmeister on Jan 4, 2017 19:01:17 GMT -5
For a target inductance, you can have more winds and less metal core, or less winds and more metal core. That's what I was trying to get across, sorry if that wasn't phrased in a good way.
|
|
|
Post by Charlie Honkmeister on Jan 4, 2017 17:16:59 GMT -5
Rather than a rail, you could just use a bar magnet as the rail. Seymour Duncan does this with some of their humbuckers: You might have to grind it down to size, though. You have to make sure the poles of the magnets exit along the sides, and not out of the faces. Yes, that's a valid approach and I think the Firebird PU is made this way. Here's the Mojotone parts for the rail PU I was mentioning. This one can use either two or four ceramic magnets which are next to the rails. In the Barden, the 2 ceramic magnets are on the outside as shown here, and there is a plastic spacer that fills the middle of the PU under the bobbins. Please excuse the extra dirt; I had to dig these out of a supposedly sealed box on the garage workbench.
|
|