fookgub

Hey Pete, could I get you to clarify a couple things about your driver? From what I understand, you started with a pickup that had individual magnetic polepieces on a steel baseplate. You scrapped the poles and baseplate, and added and a ceramic bar magnet in place of the baseplate. Then you used a single steel blade-style polepiece. Is this right? What about the neodymium magnets? Did you use those? Did you get the ceramic bar magnet from another pickup? Also, you said you used 2.2mm wire, right? That's closest to 31 AWG.

You're loading the pickup too much. The input to your sustainer amp needs to be higher impedance. That's the purpose of the common collector (drain? is it a JFET... I can't remember) input stage in the Ruby-Fetzer circuit. You uncle is right, but he missed the point. The input stage is for impedance matching, not gain. The LM386 has 40-odd dB of gain available... plenty for our purposes.

Man you're fast with those replies! I'll check that stuff out tomorrow. I've got cheapo single coils coming out my ears, so I ought be able to rig up something like yours with parts on hand. I'm going to take another crack at the Lace Sensor first, though. Anyway, there shouldn't be any grounding or loading issues in my setup. The preamp input stage is just a first order highpass with a .033uF cap and a 1Meg resistor. I grounded the copper tape around the leads to the shield, but the jack is electrically isolated from the rest of the guitar. The negative side of the driver is grounded only to the preamp, which is referenced back to the guitar ground... no loops. I did "pot" my driver with a couple coats of polyurethane varnish after it was wound, but this obvoiusly wasn't enough, and I have a feeling that coil motion is the source of most of my troubles. What is PVA? Same thing as titebond?

Ok, made some progress finally. The fret job went fine, and I have the guitar together now. The sustainer works okay up to the G-sting but requires quite a bit of coercion to get the B or E strings going. The coil is still vibrating audibly, so I'm going to have to rewind it. This time I'm going to stick closer to Pete's recipe with ~100 turns of 32 AWG wire. I'm having second thoughts about vacuum potting. We use 2-part poly for potting at work, and it dries like a rock. If I don't get it right the first time, I'm going to end up with a cool new paperweight. I'll probably just pot while I'm winding with epoxy. It would be a major pain, but I think a suitably motivated person with a razor blade could get that apart if needed. It's probably a moot point, anyway, since I'm going to try a design much closer to Pete's if the second coil on the Lace Sensor bobbin fails. It's a little early to tell if leaving out the bridge pickup selection stuff has cost me anything. I was very careful about the grounding when I wired this thing up. The system is oscillating when I crank up the gain enough to get decent sustain. I think it is mostly because due to direct coupling from the driver to the bridge pickup. I'm running at much higher power to compensate for vibrational losses in the coil and the fact that the 10-Ohm coil requires higher voltage to get the same power. I wrapped the driver leads in 2 layers of grounded copper tape, so I think EMI from the leads should be a minimal problem. Not to clog up this thread with non-sustainer stuff, but the P90 sounds awesome. I've never owned a P90 equipped guitar before (nor can I remember even playing one). It sounds about halfway between a Fender single coil and P.A.F. to me... lots of well-defined bass, nice full midrange, and a chime-y top-end that humbuckers lack. On the other hand, the Air Classic sounds awful in this guitar... very piercing and totally lacking in character, with low output to boot! Guess I shouldn't have cut those leads short after all. When I install sustainer driver v.2 I'm going to swap out the Classic for an Ibanez pickup I have around, but I haven't decided whether to go with an overwound P.A.F. or a hotter metal pickup like the BL X500 for the final install. You can't see much, but here are a couple photos of the current prototype. I snuck in a couple of my bench, too (pretty sweet, eh? ). http://www.ece.utexas.edu/~wrobert/yam2.jpg http://www.ece.utexas.edu/~wrobert/yam3.jpg http://www.ece.utexas.edu/~wrobert/yam4.jpg By the way, that comb filtering stuff is steel (I assume... it's ferrous, at least). I coated the entire thing in polyurethane varnish, though the bobbin was anodized, which is what accounts for the bronze tinge. I scraped a lot of the anodizing off in order to solder to the bobbin. Pete, Could you shoot me a link to a more detailed post about that driver? Did you wind the pickup, too? If not, where did you get that pickup with the blade polepiece? I really like the idea of having the driver on top of a normal single coil pickup. Imagine a guitar with a sustainer, a single coil, a P90, and a humbucker ....

http://projectguitar.ibforums.com/index.ph...c=22223&hl=iron

I think the tonality of the pickup is a factor with high distortion. A pickup will lots of mids will tend to cut better than something bassier. Since overwound pickups tend to have more mids they work well for metal. But it's not the high output that helps, it's the peaky midrange.

Yeah, I thought the same thing about this guitar. I got this thing for free a few years ago from a friend who had decided guitar wasn't for her after all. It's seen a number of mods and electronics changes, but luckily I never did anything awful to it (I had another guitar the got the brunt of the seriously bad mods). Anyway, the previous owner applied a large Radiohead sticker to it, which I left intact as sort of a tribute to her, even though I'm not a Radiohead fan. People always look so disappointed when I explain that one to them... For now I'm leaving out the automatic bridge pickup selection. We'll just have to see if the occasional blast of howling feedback will convince me to do otherwise . Since I'm developing the amp outboard, I just put a DPDT in for a phase switch for now. The 4PDT I had seems to have been swallowed by my parts bin, but it will turn up eventually. Yeah, the circuit will fit in the electronics cavity as long as I keep it to about 1.25" square. Otherwise I'll either put it in the trem cavity, which would be nice for EMI except that I'd still have to run a set of wires back to the phase switch, or rout an area under the pickguard below the middle pickup. I did the latter on a P-bass once and it worked out fine. For the battery, I'm going to install an 18V compartment (one of these) on the back. That way I can run the amp at 18V or at 9V and keep an extra battery in there. I finished wiring up the pickguard tonight. I decided to clip the pickup leads short since I'm too much of a pack-rat to sell them even if they don't work for me. Besides, it's always nice to have a box full of pickups because something that sucks in one guitar might sound fantastic in another.

Ok, so I've haven't really made much for progress, but I thought I'd post a little teaser to prove I'm not just blowing smoke. This is the pickguard that I'm putting into my Yamaha Pacifica soon. The sustainer is in the neck position (I've got a cover for it), middle is a GFS P90, and the bridge is a DiMarzio Air Classic. As you can see, I haven't actually wired it up yet... I can't decide whether I should clip the leads short or leave them long in the interest of resale value. The 1/4" jack in the tone position is temporary, I'm just using it while I develop my sustainer amp. The other hole is going to be for the on/off and phase switch. I was hoping to put this in this weekend, but it doesn't look like it's going to happen. I decided to level the frets on the Pacifica while I had it apart. The leveling went fine, but I discovered I just wasn't man enough to recrown with a triangle file. I ordered a fret crowning file from Stewmac and I'll have to wait until that arrives to finish this project.

Godin LG SP90. I'm not real fond of the paint on this particular one, but the Godin LG's are on my short list of hot guitars.

Pete's right... For initial testing, any old amp will do. When I first wired up my coil, I just plugged it into the external speaker out on my little 15W Fender amp. I'd like to toss in a word of caution, though: don't do your initial listening tests with a high-wattage amp! If you run into oscillations, you can really blow your ears out. I should know better by now, but I did this just a couple weeks ago when I was experimenting with alternatives to piezos. I had a small dynamic speaker clamped to the body of my bass and I was playing it fairly loudly. I decided to see what a different speaker sounds like, so I flipped the mute switch on my amp, hooked up the new speaker, hit the mute switch, and EEEK... feedback. Trust me, you do NOT want to find out how loud a ~2kHz tone can get through a 400W bass rig. My ears rang for the rest of the day. Anyway, back to the sustainer. I made a little progress on my sustainer today. I tested out the "potted" coil, and it's better but still not great. It will oscillate if I get it too close to the other pickups, and I can still hear some sound directly through the coil. I'm still testing out of the body for now. The rest of the stuff I need for the installation (pickup, mounting rings, and a 3-way switch) is coming on monday, so I'll be able to actually install the driver and do some real testing. I think the polyurethane I used on the driver is going to interfere with my ability to vacuum pot the driver, so I'll probably have to rewind it. I'm still having trouble sustaining the high strings, so if I do rewind the driver I'll probably try Pete's recipe with about 100 turns of 32 AWG wire. Again, I'll have a little better idea of what to do with the coil when I get it mounted and do some better testing. Last time I wound the driver I spent about an hour machining a bracket to mount it on our transformer winder, but now that I have that done I can wind a driver in about 5 minutes. Potting may take longer (I need to get someone at work to show me how to use the potting machine), but I could be in the position to try out a whole bunch of different coil configurations with relative ease. As far as electronic switching goes, there are some IC's out these days that are pretty easy to use. Much better than the old Anderton electronic switch from EPFM. An electronic switching system would need to be done on a PC board to make it convenient, and it wouldn't save much on wiring mess (you'd still have to connect everything that'd you connect to a mechanical switch), but it really buys you a lot of options for switch types. You could use an SPST momentary or latching, and these are available in almost every type imaginable. We'd be able to design out the pop that you've been having problems with, too (btw, Pete, you've got pm).

Where can I find the schemtics for this? I'm assuming you have a phase reverse switch and an on/off, right? What does the on/off do? Does it just enable/disable the input to the sustainer amp, or do you have power switching and automatic bridge pickup selection, too? Excellent point... I hadn't even thought about that. You keep saying you don't know much about electronics, but you've obviously considered every aspect of the design. I think you should give yourself more credit. Yeah, I don't like the way they lock you into the whole pickup system, either. I noticed on your install that you've got a single coil bridge pickup. Is it a true single coil or a stacked humbucker? I remember the Sustainiac literature saying that they require a humbucking bridge pickup to avoid crosstalk between the pickup and driver. Agreed. My installation is going to be a bit different, but I dislike the idea of trying to use the same coil as a driver and a pickup, too. I'm planning something like this: driver in standard neck pickup position, P90 right next to the driver, humbucker bridge. I like to keep my controls as simple as possible, so I'll be using 3 way pickup switching, and I plan to set the driver amp gain internally so the only external sustainer control will be a combined on/off and phase reversal switch (I managed to snag a couple 4PDT mini-toggle switches from work for this purpose ). As you can see, I'm one for really custom installs... the commercial systems simply aren't flexible enough for me. Of course this is a two way street... the more flexibility, the harder it generally is to install. Neat. It's basically opposite of where I'm headed with ultra simple controls, but it does showcase some of the cool possibilities of the system. I've found that I usually have my hands more than full on stage, so I've been trying to move as much stuff out of my guitar as possible. My piezo-equipped Ibanez has all the controls necessary to blend and switch pickup modes in mono, but I always run it in stereo and blend to mono outboard with a blend pedal or ABY box. That link points to the Manson guitar, too. Anyway, I soaked my coil in polyurethane last night, and I'll give it another hit when I get home from work today. Hopefully that will be enough to let me do a temporary install and start getting some development done on the amp. I'm going out of town this weekend, so I doubt I'll get very far, and I really need to get some of the other projects off my prototyping board first. For now I've been using a little IC amp that I pulled out of a cheapo set of computer speakers. It's actually fairly well-suited to the task, but is far too large. I'm shooting for about 1 1/4" square on my first (perfboard) prototype. The actually PCBs will probably have to be larger to make room for pin headers and traces.

wow, the fernandes system is big! I wonder what all that stuff does... 4 trimpots, two switches, and did you catch that big transformer? I've pulled smaller transformers out of wall warts! I'm guessing their coil is not as efficient if they need a transformer to (assumingly) step up the output voltage. They used pin headers for everything else, so why waste board space on those big switches? Anyway, I'd be interested to see a schematic. Judging purely on appearance, it looks a bit 'antiquated'... you know, like it belongs on one of these.

Thanks! True, but increasing the number of turns will also increase the force on the wire for a given current, or buy you the same amount of force for less current (and longer battery life). Part of the reason I used 31 ga. wire was so the I could get more turns at approximately the same DC resistance. Of course, more turns also means more inductance, so there are some trade-offs here. My understanding of electromagnetics is not what is should be, but I feel like there should be an optimal operating point that balances wire gauge, number of turns, and coil impedance. I think it will be in the neighborhood of 30-32 gauge wire and about 100 to 200 turns, but I'd like to work out the math at some point. Potting the coil while winding seems to be the best procedure. You've got some insightful comments about superglue, and I think you're right that it's not the best choice. Since I'm still in the development phase with my coil, I'd like to stay away from epoxy (though this is probably the best choice for potting while winding). For now I'd like to stick with something that is more reversible, so I think I'll give the poly a try. We've got a vacuum potting system here at work that I'll probably use when I'm ready to commit to a coil design. By delta function, I mean spikes or pulses. I'd like to see how this changes when I pot the coil. I have a feeling there is a lot of energy going into coil motion. This is especially true with more distorted waveforms, where I can here the signal from the coil as if it was a speaker. A little fuzz is probably good for this design. As you say, the compression probably help the string-to-string balance. The extra harmonic content probably helps 'kick start' the sustain process, too. I'd like to see if the harmonics the sustainer operates at for specific notes can be repeatably controlled by playing technique. This could have some very interesting uses. Is this the circuit you're referring to? It seems ok for a start, but I agree that some filtering would help. The first time I did the sustainer thing, I believe I had a sharp low-pass at around 2k and overall rising gain from ~100Hz to the 2k cutoff. If I look around hard enough, I may even be able to find the circuit somewhere (unless I've already raided it for parts). The schematic was drawn on a napkin and is long gone (it took me a few years to figure out I should keep this type of stuff in a notebook). Anyway, filtering is something that everyone is going to need to adjust to suit their coil and setup, but I think there are some possibilities for improving the string-to-string balance here. The danger is that improving the high string response with more high frequency gain may affect the lower strings' ability to sustain at their fundamentals. It would be interesting to be able to extract the fundamental (maybe with a zero-crossing detection scheme), and try using that as opposed to complex filtering. I haven't looked at it for a while, but I believe the Craig Anderton 'rocktave' circuit does something to this effect before dividing the signal down. Might be worth a look... Efficiency is king here. I'll be routing for a battery box anyway, so I'd rather use 18V, more for battery life than the extra headroom. I can see where people that won't be modifying their axes will want something that runs on a single 9V. Because this is a power circuit, battery life is always going to be at a premium. Hence the draw of class-d operation, which should be able to operate up to about 90% efficiency. The LM386 is probably more in the neighborhood of 50%. That sort of efficiency increase would be a big plus. As I recall, the Sustainiac patent specifies a class d amp, but I have no idea if they actually implemented it. A class d amp will also swing rail-to-rail, making better use of the available voltage. Most of the choices for integrated class d are going to be surface mount, but that need not scare people away. MIMF has a piezo/magnetic preamp using SMT parts that many people with no electronics background have sucessfully built. Obviously high pin count and smaller SMT form factors are out, but there may be a suitable chip out there somewhere. We would need to find something that works with a minimal amount of outboard components and uses a readily available IC. The LM4673 looks to have a lot going for it, though the available packages are not hobbiest friendly. Also of interest are some of the newer microcontrollers with built-in a/d. One of these could be used to drive an outboard h-bridge, creating a simple open-loop class d amp. It would be a neat project, but probably not practical in the end. Anyway, at this point I'm more interested in the coil than the amplifier. As you say, the driver is the key to this project. Once I have the driver settled out, and as time allows, I'd like to work on the amplifier and see what I can come up with.

You guys seem to be well on your way to a finished product, but I thought I'd share my experiment anyway. The first time I tried the sustainer thing was about 5 years ago. I rewound a vintage-style single coil with 100 or so turns of 32 gauge magnet wire. I wound the entire bobbin, not just the top portion. I didn't work very well at first, so I added some neodium magnets. This worked for the lower strings, but I still couldn't get the B and E strings to sustain. At this point other projects took priority and I basically shelved the sustainer until now. I never did any real testing on it because I didn't own any test equipment at the time. A couple weeks ago, I bought a busted Lace Sensor from a fellow PG'er. I figured I could probably repair it, plus I was curious to see what it looked like inside. It turned out the coil was broken in several places and I decided to rewind it, but as I was looking at the pickup it hit me that this would be a great place to start for a second sustainer attempt. The Lace Sensor has a very short, narrow coil that is right at the top of the pickup. Its bobbin is steel and it helps to conduct and shape the magnetic field, which also appears (although I haven't bothered to model it) to be highly focused. So I wound the coil with around 180 turns of 31 gauge magnet wire (about 10 ohms). This time I used a transformer winder, so the coil is nice and tight. I didn't get it exactly square on the bobbin (one side is thicker at the top while the other is thicker at the bottom), but I'm thinking this might actually help my string-to-string balance. When I tried it out, I was able to sustain all the strings, though the E and B still take a bit more 'motivation' to get going. Here are a few observations that I found interesting: - My coil needs to be potted -- badly. I don't think potting is optional with these devices, as the coil vibrates enough for me to actually hear the notes through it sometimes. This can't be helping my efficiency. I've thought about wax potting, but I don't know if the wax will be able to wick into the coil well enough to stop it from moving. I think CA (super glue) would be quite effective for this, but it would be very permanent. I saw a mention of lacquer earlier, and that seems like a good compromise. I have some polyurethane around, so I think I'll try that first. - The wave going to the driver in my setup is not even close to a sine. It looks more like periodic series of a delta functions with alternating polarity. This is not what I expected to see. I figured the sustainer would settle into a frequency it liked then sustain at basically one pure tone. I have a feeling this has something to do with the potting, as the coil has a resonant frequency that is a combination of both the electrical and mechanical parameters, and it will try to settle into that if I let it sustain for too long. - I needed about 10V peak to peak to get the strings sustaining nicely. I hope that potting the driver will gain me a little in the way of efficiency, but it looks like I'm going to need all the voltage I can get from a 9V. I've seen some mention of the LM386 as a driver amp. It's a nice chip because it's cheap, simple, and fairly capable. It does not swing rail-to-rail, though. The typical peak-to-peak output at an 8V supply into an 8 Ohm load is around 5.5V. I plan to look at some circuits that can get closer to the supply voltage. A discrete implementation is probably all that is necessary, but I'd like to take a look at some of the newer MOSFET output opamps and line drivers that are around. Anyway, I hope these observations are welcome. It may be a while as I have about 10 times more projects than free time, but I think I can improve on current amplifier and possibly even provide some PCB layouts.

There are several ways to make a delay circuit. To my knowledge, none of them are remotely simple. Of the circuits I've seen, I wouldn't attempt to build any without an etched or printed circuit board.

That's GOTM material right there. Very good work, I like it lot.

Yeah, those are real wood, as are SX basses and Agile guitars, both of which seem to have a pretty loyal following. Most people consider them 'fixer-uppers'. If you want something the plays really well, be prepared to do some fretwork. You might end up swapping the tuners and bridge, too, but I'd wait until you got the guitar to see. As far as tone and pickups, I don't think you'll go wrong. Remember, DiMarzio has an exchange policy. If you try the X2N and hate it, you can exchange it for something else. Honestly, I'm in the 'tonewood skeptics' camp for solidbodies. I think the density and weight of the body has something to do with the tone and sustain, but I don't get hung up on species. Also, no one has mentioned the neck's contribution to the sound. Which do you think vibrates more freely, the body or the neck? Fill in the front pickup rout if you must, but then you're committed to refinishing the guitar. You won't notice any change in tone from filling it, so I'd leave it as is... a little variety never hurt anyone. If you want to do it for aesthetic reasons, I understand... making something look cool is a powerful urge, so if you have to do it then good luck. As for chopping off the body, don't do it... it's just too much effort. You might as well buy a Carvin neck-through and start from there. It would be about the same amount of work.

Well, Gibson's been making this thing called a 'Les Paul' for a little while. It's got a mahogany neck, but doesn't really seem to be taking off. Seriously, though, mahogany is a fine neck wood.

This does not make sense. I don't understand why manufacturers do this type of thing... it's like they deliberately want to confuse people. Anyway, I don't have much love for Behringer. This could be a fine cab (I don't know... I've never heard it), but it looks cheaply made, and Behringer doesn't have much of a reputation either. For a bit more cash you could get into a lot of better stuff. Give a thought to Carvin and Avatar. Also, look for used stuff. I saw a Marshall 1960 stereo cab go for $300 a little while ago.

I agree with the comments about a temperature controlled station. Spend the money once for something decent, and you'll save yourself a lot of headaches. I always liked Wellers, but I use Xytronic 168-3C. It's a fantastic little station for about $100. Tips can be a bit tough to find, but I know All Electronics has them (that's where I got the station, too). It's got a 45 second warm up time, so I usually turn it on, go wet the sponge, and it's ready when I come back. I use a Metcal MX-500 at work, which is just awesome, but it's definitely overkill for most hobbiests.

I can't help, but I will say the M800's are cool and I've been looking for one, too. I've had an ongoing search up on eBay for about the last three months, and only 2 or 3 have come up. They don't appear often. Good luck.

I wouldn't trust a booster/preamp pedal to have the kind of input impedance you're going to want unless it's specifically designed for piezos. Honestly, the Tillman preamp I referred to before is a very clean solution, and it's one of the easiest circuits around to build. If you don't want to have a preamp in the guitar, then you'll want to hook it up as follows. If your guitar has a mono jack, you'll need to switch it out for a stereo jack. Leave the stuff for the magnetic pickups intact. Everything having to do with the magnetic pickups should come out on the tip terminal of the output jack. Bring the piezo output directly to the ring terminal of the output jack. You can keep the on/off switch if you want, but you'll need to remove any volume/tone pots on the piezo side. These controls need to come *after* a preamp. Now you'll need to connect your guitar with a stereo cable whenever you want to use the piezos. The piezo side of the output needs to go directly to a preamp, then to an A/B box, mixer, or whatever else you plan to use to switch between magnetic and piezo output. The magnetic pickups can go directly to your mixer, A/B box, pan pedal, or whatever. This is only one of many ways to get set up, but it's probably the simplest. You could also use a dedicated acoustic amp. After the piezo preamp, you can put a volume control, effects, or whatever else you want. The key here is that a preamp must be the FIRST thing the piezo pickups see, and the piezo and magnetic signal paths need to stay completely separate until after that.

Sure. I believe Craig Anderton describes something to that effect in DIY Projects for Guitarists. It might be tricky to get everything back into the pedal housing, and you'll want to be careful with your leads (especially around gain circuits), but it can be done for sure. It's probably a better idea to use resistors rather than trimpots once you've found the settings you like. That way they won't change if the pedal gets knocked around.

Thanks for the advice. I'll stay away from oil & wax. I think you're probably right that it isn't an oil finish. They would definitely say something about taking care of it if it was. Guild recommends a specific cleaning spray that I'll look into. I don't actually want to polish it... just clean it, so I'll stay away from polishes, too. I'm starting to get pretty curious about the finish on the guitar, though. The neck, especially, has a very raw feel that I usually associate with oil finishes. I guess it must be some sort of thin poly with no grain filler. The neck has turned a pleasing tobacco brown in my favorite playing positions, and it seems to have picked up some oil from my hands, which makes it feel very fast and 'broken in'. When I finally start building my own axes, on of my first projects will be a mahogany-necked solidbody, and I'm hoping to be able to re-create the feel of this neck.