Sustainer Ideas

[psw]

Alright, we have at least one guy replicating my current sustainer!

Transient/emre

I've given Emre some tips. He's go 0.3mm wire. That's fine, maybe better thicker wire=less resistance=more turns. He has also just recently built the little gem and has a junk ceramic single coil to play with so he's well ahead. Hopefully he'll have that fretless singing for us before long so we can see how it's done.

Meanwhile, I drove over to the supplier of magnets and got some more supplies. If all goes well I might even wind and test drivers and sell people simple kits to do your own.

I'm going to build another driver like my prototype with internal magnets, slim enough to fit to the surface of the guitar to avoid having to route and/or remove pickups.

I also got supplies for my Neodymium or Rare Earth magnet pickup concepts. Price wise, alnico is significantly more expensive, not only for the power but even in size. I also got some ceramics that may, due to their shape, be more applicable to my driver design that I have planned.

Anyway, I'll have a bit of a play around and see what comes along. Let me know if anyone else is about to have a go in case there is anything I can suggest or clarify for you guys...

Oh, here's one, bobbins are probably the hardest thing to come by or make but you can successfully make your own out of plastic folders and super glue for instance. If anyone else has suggestions too, please post 'em.

best of luck

psw

[psw]

Okay, so I'm hooked on sustain again...

I made a blade driver and here are the specs...

....3mm wide steel blade 3-4 mm high (bog ordinary hardware stuff hacksawn and gound to a shine and the ends rounded.

....bobbin made of plastic (for the top) and thin cardboard below

....bobbin width 1cm by 6.5mm long (looks like narrow humbucker bobbin)

....potted and cardboard reinforced with superglue

....0.2 mm enamel wire

I've tried a few magnets but the really strong ceramic that I've been using for my last one works best. I'll try some neodymium tomorrow, smaller ceramics didn't work too well.

The intention of this driver is to fit on the bridge side of the neck pickup on my Les Paul. I'm planning on mounting the controls on a brass extension to the scratch plate which is elevated above the arch of the top. There may even be room for the circuit if I decide to get tricky. The wires from the selector and the battery, etc will be able to reach the controls from under the bridge humbucker's mounting ring.

OK, so how does it perform...bloody beautiful,...at least on the test guitar. On the strat even the middle pickup can be used (but not the neck where the driver is).

Now, I have never played a sustainer guitar before but, I'd be surprised if they worked much better. It does what I was aiming for at least which is clean feedback or sustain without distortion and it's a great sound. The sensitivity control helps tailor the response and it seems very sensitive to the players touch which is a good thing. Along with clean sustain, I like the idea of notes, just fading into an octave and it appears to do that ok. A light touch will give you those violin type dynamics without touching the volume control.

So the trick will be to get the driver slim enough to surface mount. The key to this will be the RE magnets. These could be put in the core or below the blade. I made the blade as it's the better design overall and the easiest for you guys and if cutting into your guitar isn't a problem then it's virtually guaranteed to work for you.

So, no excuses you guys, get your stuff together, I need as many DIY sustainers going so that you can help me get the device to the next stage...boy I wish I hadn't taken that turn on page whatever into hex drivers, I would have gotten here a lot sooner. To be fair though, I found two other prototypes that also worked, but these designs I'm using now do have the edge 'cause I'm a lot better at this stuff now.

Anyway, this is good news and I really do hope that you give it a go. There is a whole lot of new music to be made with this device I'm sure, and that's what has really driven this thread I hope, 'cause that's what it's all about...

pete / psw

[GregP]

Exciting!!!

I can't 'give it a go', though, because most of this thread is Greek to me. I just read it in order to stay updated and cheer you on.

Greg

[psw]

It's pretty easy Greg if you ignore everything up to the last few pages. (oh and pull your finger out )

But thanks for cheering I'm excited and once I've got this thing really to my liking I'll run a step by step with pictures, perhaps on a new thread or tutorial so you guys can see how easy it is.

O.2mm wire is nothing like as thin as pickup wire and so winds and solders better for those who'd otherwise tangle up a pickup. The hardest part (except getting the concept to work originally) is to make an attractive bobbin.

Now, before I fall asleep here, I just did some experiments with tiny neodymium magnets and they work OK too. You need a few of them though but they can be placed on the back of the blade to help compensate for the diferent string guages and responses. This is particularly cool as this is what I have been attempting with the Hex drive but now it's done by simply spacing out the magnets more and less till the desired response is achieved.

The high e is always going to be more difficult to drive unless you've got really heavy strings I suspect (I use a 10 as it is) or tune down or have a shorter scale to relieve tension, but it does work and can be compensated for in the player's style.

The results of the tests that I've just done makes a complete blade driver 6mm thick in total, just enough to squeeze into position on the Les Paul as planned. There is the possibility of making the same design even slimer with say 12 neodymium poles. If that works the thing will fit on just about any guitar!

anyway, sleep awaits

pete

[Matt]

hey im gonna try this but when i have the money, BUT

what would a RE magnet PU sound like?

Im thinking of putting sone rod like RE magnets in a humbucker (Evolution type) and using the magnetic permiability of the screws to dampen the force so it doesn't rip off my strings

would this work and what might one sound like compared to alnico or ceramic?

cheers

matt

[Kyle Cavanaugh]

OK, I drew up the schematic for the amplifier (N-Junction FET input stage going into a 386 chip) in one of my study halls (being able to look up datasheets on the school library's internet computers helped). It's a pretty simple circuit to assemble.

[psw]

Sorry about this, the run off groove amp that I was thinking of is the improved little gem amp called Ruby...sounds like the sort of thing you've drawn out Kyle...here's a link to what I mean:

Ruby

I use a preamp for more gain but have low powered single coil pickups so it may not need it on a hot humbucker equiped guitar. I'm sure someone will be able to show us how to get some preamp gain from the buffer with a change of a resistor or such. I haven't got round to testing it with the driver but I've made a simple lowpower op-amp preamp with a 10x gain into the LM386 circuit and use a 10k pot on the input after the preamp.

The LM386 is pretty adaptable and fairly indestructable. The Ruby circuit and all it's variations are simply based on the maker's Application Notes.

Your not looking at a lot of expense Matt. Making something that will fit onto your guitar without hacking away at it, now that's a little trickier!

Now Neodymium or Rare Earth Magnets are extremely strong for their size. There is a school of thought, which I subscribe to, that says a magnet is a magnet no matter what it's made of. The only thing to say is that it's not simply about magnetic power, too much and you'll suck the strings right off your guitar, but there is the matter of size/power ratio that most people don't appreciate. Because you can get the same amount of power (or pull) in a much smaller package, it radically changes the shape of the magnetic field. RE magnet's then, of equivilent strength, make a very small focused field. You can use steel and such to redirect it and you'll need to because of the way pickups work.

So here's a little to remind us how they work...You've got a coil of wire and the string within a magnetic field. When the string vibrates it disturbs the magnetic field and induces a current in the coil which can then be amplified. What creates the magnetic field is not so important, Ceramic, Alnico, Neodyminium as the shape of the field created. Now with a ceramic magnet of the same power you typically get a large block stuck to the bottom of some steel (blades or poles) that helps direct it towards the strings. Some will have alnico rods as the pole piece itself like a traditional fender single coil. This will make a different shaped field.

A Rare Earth Magnet of the same strength will be so small and it's field so compact that you'll have a radically different field. But is this desirable. Not particularly for a traditional design because of what I said in the start of the above paragraph: You want the coil and string in the field. You may find that you've got more string and less coil or visa versa and lose power even though you have a more powerfull magnet.

That does not mean they can't be used, I've got some ideas, and it's from these that I came to use them in the sustainer project. You may find you could create a really compact pickups or pickups with a lot of focus. As there has been little work being done on new designs (every one wants the traditional single of humbucker pickup size and sound) there's a lot of scope here for the experimenter.

I'm using them here, for instance, to get the driver compact enough to fit on the guitar. The relative small coil or other drive designs mean that I require a small powerful field. That's probably not what's required in a typical pickup design.

Also remember that in a typical humbucker one side is north and the other south and what looks like magnetic poles are in fact just steel slugs and the magnet, whatever it's made of, lies below and between the two bobbins.

One last thing, I've been using magnets only 2mm thick and they pack a bit of punch. Something this small, powerful as it is, may not be of much use as you may imagine, even with a screw used to extend it into a pole.

If people are interested in playing with magnetics and learning a bit more about it, there is a free computer program called FEMM that will allow you to build in 2d various magnetic structures and display the magnetic field as it reacts to magnetic and non magnetic materials.

Anyway, once the sustainer is out of the way for a while I'll be trying to put some of my Rare Earth powered pickup ideas to work but don't be fooled into thinking that there's some kind of magical mojo in the magnets it's the total design that creates the sonic signature of the device and to this extent, RE mags may allow for a different type of design and therefore different magic to be created.

Well enough from me, I take it then Kyle's puting together one and Emre so there's a couple of people but I see this thread has just clicked over 11,000 visits so I'm sure there's some others who might like to give it a go!

Check you later

psw / pete

[Matt]

yea i understand what your saying, i have some 5mmx10mm rod RE mags and i can tell you strong is an understament! but what i foound was if they are connected to a screw or something, the magnetism from that screw (polepiece) seems to be alot weaker than that of the mags themselves. Here is what im thinking.

=========== strings

----0---- ----0---- top of boobin

.....0...........0.....

----0---- ----0---- bottom of bobbin

.....0(====)0 cylinder magnets horizontal like a bar magnet

where we are looking at a cross section of a humbucker,

--- are the top and bottoms of the bobbins

0 is the polepieces or screws

(====) is the magnets

.... are there to get everything central

the reason i ask, is because i want to make a sort of 'super evolution' type PU for a Jem. I like the original Evos but i also what an alnico type tone for stuff like satch. im just wondering what RE might sound like?

Any ideas?

Edited April 7, 2005 by Matt

[psw]

Well, Ok you seem to have a handle on the concept so,

If you think one mag that size is strong, imagine 6!!!!!

Anyway, since they are not pointing at the string as I originally thought you should be ok. Adding the metal (screws, whatever) doesn't decrease the power, it doesn't alter it at all in fact. What's happening is that the metal is being magnetised as much as it possibly can. So in your drawing the magnetism will extend past the poles in both directions under the humbucker and extend in a big arc. This is the benifit of a program like FEMM in that it will show the field and strength at any given point in everything from steel to air in glorious color.

I don't know what it would sound like though. It could be less distinct as the magnetic field is larger and sampling a bigger portion of string. It may however be sharper if the permiability (the amount a substance can be magnetised) of your poles are high.

Personally I wouldn't be risking damaging an already fine pickup for an unknown like this. You may find that your ideas make a cheapo pickup a lot better though so perhaps experiment with something like that. But then I'm a little chicken like that...I wont be drilling into my Les Paul to fit my sustainer switches for instance.

just me though

pete

[Kyle Cavanaugh]

Here is what im thinking.

===========    strings

----0---- ----0----  top of boobin

.....0...........0.....               

----0---- ----0----  bottom of bobbin

.....0(====)0      cylinder magnets horizontal like a bar magnet

where we are looking at a cross section of a humbucker, 

--- are the top and bottoms of the bobbins

0 is the polepieces or screws

(====) is the magnets

.... are there to get everything central

←

That is what I was planning on doing with this new pickup design of mine. I think the reason a ferromagnetic material won't be charged up well by a rare earth in the IMMEDIATE vacinity is because since they are so strong, the magnetic field will be huge and since they are circular if not acted upon by an outside force (the iron will distort it), there's only a little bit of the magnetism affecting the material. Maybe if you took say a narrow (1/8" would be plenty probably) rare earth bar magnet and had it in the middle in place of the bar magnet on a normal humbucker. Bill Lawrence does this with a 1/4" ceramic bar on his L500 series.

Regarding my amplfier driving the thing, it's definetely different. The input stage is a Common-Source (based off of Don Tillman's design) on it while that is a Common-Drain. That one amplifies current a great deal and has less than one voltage gain, while mine amplifies current and has about 2 voltage gain and amplifies current as well. I also have a 10uF cap acrossed pins 1 and 8 for a lot more gain on the LM386. The FET I got (as it was the only small signal audio one I could find in any of the junk boards at school) is a 2SK163 which I believe is an N-Junction MOSFET. I got it out of the radio reciever on a fairly new car stereo (don't worry, it was already broke beyond repair). The pickup I'm using for the input is a Bill Lawrence L280 which is an extremely low-noise, very clean single-coil sized humbucker. It was TOO transparent in my guitar which is the reason it didn't stay.

Wait a sec, the max input voltage on the LM386 is only like 400 mV! I suppose if I want to keep a clean signal when volume is turned up (I got a 10K pot after the preamp), I better go with that kind of input stage. I'm pretty sure the impedance is lower on that one too, so I think there might be less noise.

[lovekraft]

Keep in mind that if you're using a 9 volt power supply, you're absolutely constrained to less than +/- 4.5 volts on the 386's output, so if you set the gain to 200X, any input signal over +/- 22mV is going to be clipped at the power amp output (actually less than that, since the 386 won't swing rail to rail). That may or may not be a good thing - it will compress the signal somewhat, but it will also color the string's vibration somewhat, so it may be a tradeoff.

[psw]

Hey LK, I sense some de-ja-vu. Man is this page 46 or page 3!!!!

Seriously though, sending a compressed signal or a squarewave will drive the string. You're not going to ever get a string to actually drive at a square wave.

What I've found that such signals (compressed and squarewave) tend to make the strings respond perhaps a little quicker and jump to the octave harmonic quicker (when not in harmonic mode) but they also dramatically effect the polyphonic response in favor of the strongest responding string (often the lowest but not always).

My preamp goes well into the square wave area...testing is easy, connect a speaker instead of the driver...but will still drive at 1/2 way and below on that gain pot. Above about that level it's really being saturated but it's worthwhile to have that capacity there.

I'd like to bring back something else from earlier in the thread. Most people see the sustainer device as purely a method of creating feedback sustain but I think that there's a lot more potential...if only I could come up with a more convincing name (no let's not for now!) but I envision it as able to add another level of expression.

For instance, with the sensitivity turned down you can get the signal to jump your harmonic while still preserving the natural decay or to extend the decay of notes on a pingy strat or hollowbody. Turned up it gives you (if you've got the technique) to do those holdsworth or satriani legato style with the absolute minimum of picking. I previously liken it to the tremolo arm, you can use as little or as much as you like, it's not all about dive bombs! What I like best is that it can do this with a clean sound which is controllable, This is a sound that even with a really loud amp is hard if not impossible to achieve (of course you can process and distort that sound as much as you want)

OK, so you may find it hard if not impossible to find magnetic bars of Neodynium magnetised on it's sides. The shape really doesn't matter that much and once you get smaller than standard your having to compensate for their lack of size and then the reason for using the Neo is defeated.

Ferromagnetic materials (and I've forgotten the exact terminology so I'll try to avoid it) have two propperties of interest, the ability to take up magnetism and their ability to hold or change those states. I've done a bit with ferrite (not magnets, the basic material) because they take up magnetism very well but don't hold a charge. That's why you see them in radio antenna coils and noise suppression in leads. Powdered iron and laminated cores have an interesting effects in this regard. If you want to learn even more you start getting into the "domains" within materials and the way they align, eddy currents and the like.

As far as magnetics go, I'm self taught from books and playing with FEMM models and actual magnets and coils. The FEMM models give you an intuitive feel and visualisation for what these invisible forces are doing. You can try all types of magnetic material and ferro- and non-magnetic materials and see the extent that the magnetism is taken up and effected by materials.

Here's a page of useful links including links to the FEMM program a tutorial and other stuff.

magnetic links

Steven Kirsting, guitar builder and pickup maker has done some modelling of traditional and his own variations. (I asked nicely and he emailed me the FEMM files so I could play with substituting materials. Magnets are really quite amazing cause it's the invisible magnettic field that your trying to harness and these have weird properties like being able to be bent and deflected or to pass through completely uneffected by seemingly solid materials like aluminium (which as it happens is slightly anti-magnetic not simply non-magnetic...but not enough to be useful, just interesting).

Here's some links to his practical application of the program in pickup design.

SK FEMM Pickup Models

Steven's site is a must read for you in relation to pickup designs and he's president of the pickup maker's forum on MIMF. There is a lot to read about pickups and what's what but there's an equal amount of hype so beware.

anyway, that's enough for now, I hope this is of interest to people and they give some of this stuff a go. There's no charge for learning stuff even if you dont what to do it!

pete / psw

[Kyle Cavanaugh]

You could use a bridge rectifier running into a capacitor (to take out the DC bias) to double the frequency (octave up, 2nd harmonic). I *think* if you ran diodes in series with the signal (to cut off the bottom) and ran an electrolitic cap in parallel (+ to +, - to -), you'd get a decent octave down (2nd sub-harmonic), I could be wrong though. but the fact that around .7 volts is dropped acrossed a diode should be taken into consideration, you'd need an amplifier stage driving it that had somewhere between 2 and 4 voltage gain to keep it from getting too quiet. Of course if you want to get it more sinsoidial you could run it into another common-emmiter\drain stage and tweak the way you swamp it to adjust symmetry and such. A summing amplifier (an op-amp circuit) could be used to mix the wet and dry signals together. You can use logic chips to change frequency pretty easy (if you know what you're doing), but you'll get square waves because of it either being 1 or 0. There are ways to unsquare a square wave, though.

I bet the fact that there is a sharp attack (it looks like an inverse square function) when you run a sine wave through a Schmitt Trigger might have some benefits for the sustainer...

I don't smoke, but I need this! LOL

[psw]

That's fantastic Kyle, do you have to be put into a trance to come up with a post like that!

Seriously though, I understand it but I just don't know how to implement those ideas. My last driver technology works from the bridge but I've abandoned it for now because there are too many complications. One was that you had to have just the right combinations of phase of both (all) the guitar's pickups which would probably mean digital switching, strategies as you've outlined for harmonic switching and attenuating the guitar's output. The benifit is that it is very small, does not involve coil winding, is a hex design (better polyphonic response), and because it uses the bridge pickup like a transformer with the drivers, uses a lot less power.

The kind of things your suggesting are in line with my thinking with putting "effects" into the drive signal.

Something which is probably of most use is a way to vary the phase of the drive signal to varying degrees (probably between 0-90 degrees) to aid in the driving of high strings where the phase difference is more pronounced. The Floyd rose patent describes an A/D converter to switch in various capacitors to compensate for "phase lead and lag" between the strings physical vibration and the actions of the driving coil/mechanism.

I tried diodes across the output and in the preamp but had little effect (but then I'm an electronics doofuss, as I've confessed before!). I've got a half wave transistor based "effect" that's supposed to make a sound like a steel guitar. My intention was to try that to see what happened with this thing. On my original experiment I connected a flanger to the drive signal and got an interesting physical sweep of the strings harmonics. A problem is that all these things consume more power and it takes a bit to drive a string as it is. Plus, it's hard enough for me to keep things simple.

What I think this thread has shown is that factors effecting drive efficiency can be addressed in the driver design. To that end I'm looking at making a two blade design next. One for each set of three strings with different windind wire and adjustable magnet strength.

But all this will have to wait a bit. I read an interview with Vai where he says that he used the Sustainer quite a bit (and his fretless triple neck sustainer) on his new album. Meanwhile it looks like I'll be away in a few days.

catch you later

pete

[psw]

Before I go away, here are a couple of photo's of the two drivers that I've been talking about:

One is a steel blade and you can see the relative size of the little Neodymium magnets (silver 3mm discs) in relation to the much larger ceramic block, which is about the size of the coil bobbin, on the screw pole piece driver. Both give similar responses but the magnet(s) is much smaller and probably of a similar expense ($) !

You can see how compact a coil you can make with the blade version. The top of this is made of thin plastic with a slot cut for the blade, the bottom is simply some thin card, the ends are bent over. When I get back I'll make one with Neodymium inside the core, like my old prtotypes, and I anticipate a complete driver only a few millimetres thick, magnets and all!

OK, so that's all I've got for now,

pete / psw

[Steve Vai]

I'm back; I've been pretty busy lately. How's everything going?

Edited April 10, 2005 by Steve Vai

[psw]

Welcome back Mr. Vai...you've been gone a while, I wondered what had happened to you.

Firstly, you bumped my pictures of the drivers by your post on page 47. If people missed it there are a couple if pics on the last post of the previous page.

Now, if I remember right, you wanted to put a sustainer on a single bridge pickup guitar. Well I've got good news for you. Not only is that going to be the easiest to set up as far as switching, I'm planning something much the same!

I've now got 2 different easy to make driver designs and I'm giving all the specifications and support I can to help people make them work.

As for my guitar plans. I'm thinking of a left handed strat shape, modified for upper fret access with a left handed strat headstock. I've got the neck and I plan to make the body, back half wood (probably ash) and the top a foam reinforced aluminium hammered into your typical strat like curves and contours. I've cut out the body template already and I kind of like it. Hendrix always looked so cool and it's got a bit of the mosrite look with the extended lower horn.

I've got a gibson humbucker somewhere which will be in the bridge and I've just tested using a single piezo in the neck pocket and it works and sounds pretty good. Will probably need a bit of a preamp and am thinkin of using another for a bit of a boost function and of course, a sustainer in the neck position.

The only new developments I can comment on is that I've added a U shaped metal channel to the blade driver so that the back side of the magnet sits on this and helps focus the drive signal. This helps address some of the problems with the high e string. I think some substitution of the output capacitor from the 220uF to something lower will also help with the high frequency response.

Anyway, Master Vai, I'll probably be away myself for a little bit starting tomorrow, but read back over the last three pages and you'll be right up to date. I hope I can count you amoungst those who are going to give this a go.

check you later...I'm sure I'll be able to sneak out to some internet cafe from time to time to check up on things while i'm away

see you guys then

pete / psw

[Steve Vai]

I'm leaning towards a guitar with a humbucker in the bridge and a single coil in the neck, but it's good to see it'll work either way.

A piezo in the neck pocket can be used to give the driver the signal? I have one of these (http://www.stewmac.com/shop/Electronics,_pickups/Pickups:_Guitar,_Acoustic/Schatten_Soundboard_Transducer.html) lying around, could I use that?

[Kyle Cavanaugh]

I'm leaning towards a guitar with a humbucker in the bridge and a single coil in the neck, but it's good to see it'll work either way.

A piezo in the neck pocket can be used to give the driver the signal? I have one of these (http://www.stewmac.com/shop/Electronics,_pickups/Pickups:_Guitar,_Acoustic/Schatten_Soundboard_Transducer.html) lying around, could I use that?

←

Edit: Opps, my bad, thought you were saying it was the driver!

I believe it will work, Piezos like that can feedback like crazy!

Edited April 11, 2005 by Kyle Cavanaugh

[psw]

Hi Guys...

Well I've been able to find an internet cafe nearby the hospital so I'll be able to drop in from time to time...

I tested a standard Radio Shack / Dick Smith / Jaycar "piezo transducer", basically a buzzer without the circuitry, I'm sure a lot of you will know the ones. Anyway, took the plastic case off it and connected some wires to it with no preamp and loosened the neck on my strat copy and placed it in there with the wooden shims I'd inserted to raise the neck a little (2mm) to get my drivers in there.

Anyway, yes it does work. A preamp will be needed to mix the signals to prevent loading. The sound is a bit bassy (may be the lack of a preamp and fairly long partially unshielded cable) but the signal was quite strong and the sound far less "quacky" than when mounted on the bridge. Handling noise was very low and none of the handling noise you often experience with bridge mounted systems when dampening strings!

How it would go as the source signal for the driver I don't know. I don't see why not and if one was clever, the driver's preamp could also be adapted for dual use for the piezo and the drive system.

It's certainly something to explore.

As for my guitar idea, I've got some parts about enough to build something and I'm keen to get my driver design into a better functioning guitar.

Meanwhile, I've smuggled an acoustic in with me and hope to get a little playing in to while away the hours.

I'd better get back before they miss me, hope some of you are going to build yourself a driver and share your design ideas.

See you then

pete / psw

[transient]

Hope you're well Pete. I'll start experimenting when i have some free time (i'm pretty busy at the moment), and i of course would share my experiences if i somehow can get it to work.

...

emre

[psw]

I still drop by, (thru the internet cafe) if people have enquiries about making their own sustainer. Still away from home but I went back for a day and my sustainer is still going strong. Even running on the same battery which surprised me!

The last modification I made was to put jaguar pickup like fins or U-channel on the fin driver. Basically some metal from the lower poles of the magnets on the centre fin up the sides of the coil. Theoretically, this type of strategy keeps the feild more compact. I'm not sure if it has made much of a difference to performance.

In part, I was hoping for increased sensitivity for the high e string which responds poorly compared to others. The b string is fine. Perhaps it's not so much the magnetism but the resonances in the circuit and coil that produce this effect. I've tried adding more magnets to the fin to increase response and that has had some effect. The d string is probably the next least responsive. But don't get me wrong, all strings do sustain.

I see that sustainiac and fernandes both have trouble with the high e and b. Sustainiac use "shunts" to add a little more metal to the sides of their design I believe (or so it suggests in their patent). That's why I did the fin thing, in part, but does not really fix the problem.

In general, my approach of having a very thin compact coil, as opposed to typically, pickup sized drivers, has advantages, not just in the potential to mount the thing without too much modification, but to focus the driver right under the string. The big ceramic magnet still works best but at the moment I've got it rigged up with 2mm thick neodyminums. When I get back to it, I'll do one with internal magnets and see if this does anything for the design and performace equation.

Anyway, just thought some of you may have missed having anything new happening on the sustainer project, so, hope this satisfies for now...

'Till later...

psw

[onelastgoodbye]

well i've built the little gem amp and threw a driver together but all I get is screaming high pitched feedback. blah. the driver wasn't properly potted so I guess it's just really microphonic. I'll throw some epoxy on there and see what gives. the gem seems to work fine by itself though.

the driver I built uses 0.3 mm wire,with a piece of metal 15 x 57 x 1(!) mm as a blade. For some reason i think a very narrow blade is the way to go. the coil is about 5mm high and came to about 2 ohms (that seems to be pretty low but it was certainly powerful enough to induce feedback 30 cm away from the strings ).

I think I'd might have to tame down the little gem too. There's way too much overdrive too my liking with the emg's. You can actually hear the distortion of the little gem rattling the coil, through the strings into my main amp. I'm probably experiencing too much of the lack of headroom on the lm 386 (Lovekraft alluded to that couple of posts ago).

Hope all is going well psw,

Tim

[psw]

Well, I'm glad someone's giving it a go! Good work Tim.

Feedback is to be expected you know! I'm guessing your testing it by holding it over the strings. Try to hold it way up the neck away from any pickups. It may be that your generating a really wide electromagnetic field and your pickups (being preamped already) are super sensitive. We can discount any microphonics from the the EMG's as they'ed be well potted so lets concentrate on the coil.

Drop the amount of input. A 10k pot on the input or a 1k trim pot across pins 1 and 8 of the LM386 can control the amps gain. Being preamped already, you could even get away with no buffers as your EMG's are buffered to low impedance by their internal preamps. The cascade of buffers may be causing the distortion. Too much gain / distortion may be a part of the squeel problem.

If your coil is at all loose, you may even feel the coil vibrate. You definitely dont want that. However, if it is that loose you should be able to pot it fairly easily with something like PVA. This will take a long time to set but because of that it will be able to seep in and fill those spaces. Being a little flexable you don't risk the coil becoming too hard and the vibrations stripping off the wire's enamal coating and causing a short. I used PVA on both my test drivers. You can even put a little on the bobbin and wind over it. The excess PVA is squeezed out by the layering ensuring absolute coverage and no voids. PVA is low tech. Nail varnish (your choice of colors) will dry really quick but you'll need to add it as you wind from time to time.

A 2 ohm coil is a little low. You might want to try adding a 2-6 ohm resistor to give the amp something to work against with the coil, just to tame it down a little. It's really after a 4-8 ohm load for best efficiency and this might make it a little happier. This is the problem with the choice of wire. Even though I used 0.2mm wire that extra thickness makes for a much larger coil and effects resonant frequencies of the coil and circuitry and hence the efficiency it will drive certain frequencies.

Now, just checking a few things. You're trying to drive the strings up by the neck and taking a direct feed from the bridge pickup and have the bridge pickup selected (only) for the output, yes? The driver and it's source pickup have to be far enough apart to avoid the squeel and the nearest pickup needs to be disconected (ie not selected) also. Hold the driver really close to the strings also.

Another thing...you didn't mention the magnet you were using. A strong magnet really helps keep the electromagnetic pulses from the coil from straying all over the place (also my external channel fin idea has a similar effect in theory) and interfering with pickups. No magnet on the other hand will provide little to no drive but a huge electromagnetic field that will interfere with everything.

As for the thin blade....hmmm. Something tells me thicker would be better. Mine's 3mm thick. If you have thin stuff layering it with some insulation (even superglue or whatever) will create a more efficient core. My best cores from the past were made of pure iron powder epoxied and let to set in a magnetic field...don't get silly and expensive like I've done, it doesn't matter that much! If you look at a sustainiac driver the "blade(s)" are probably at least 5mm wide (thick). My reasoning for a wider (thicker) blade or poles is to avoid poor response on some notes and harmonics by vitue of the driver sitting directly under a nodal point (zero vibration). This is unavoidable, but with a wider blade you will be able to lessen the effect because, like pulling the harmonic from the 12 fret, it's a precice location and a wider blade will be able to extend it's influence beyond those precise points...if you get my drift. Another reason is that it makes the insided of the bobbin, from where you wind, bigger and thus each wind longer and take less winds to reach a given ressistance as a result. It may not seem like much but if you wind a coil, it can take quite a while to get to say 4 ohms and then hardly any more to get it up to 8, mainly due to the effect of the winds getting ever increasingly longer with each layer of winds. Also, your blade may not have the permiability to take the amount of magnetism your applying, being completely saturated.

Anyway, these are all things to consider, simply potting it may help and get the thing working. My first one picktured in the previous page had a 5mm thick coil but you can see from the side view that the blade version is about 3mm and I think it works a little better...maybe it just looks better, who knows. They both work better with the giant ceramic magnet dispite the enormous condensed power in those little silver neo's you can see there on the side view of the smaller driver.

Well, I'm still not well and I'm still in hospital and I have to sneak out to access you guys but I'll be dropping by so I hope this helps a little. Let me know how you go.

Anyway, that's it for now. By the way, if your interested in a completely unrelated (well almost) psw thread, check out the stepped fret discussion in the solidbody and bass section of the forum...some interesting opinion and stuff happening there. I'm not sure it will end up being the marathon that this thread has been, but you may enjoy the banter!

time to get back before they send out a search party (again)!

psw / pete

ps...Tim, I just re-read your core specs...1mm thick but 15mm high with a 5mm coil. I'd get that blade to the height of the coil or round abouts. The blade is three times as high as the coil. That may be a large part of the problem. Also how does the magnet attach to a core that shape?

[psw]

I'm back home, still a little unwell, it may take a while to recover.

But, at least I've got more access to a computer and my little experiments which I think I'll be finding theraputic anyway (a little like basket weaving with wires and solder )

Now Tim, and others. I've just realized that there are a few "little Gem" versions. I don't know how or why they came up with the "LITTLE GEM" circuit. I'm sure it works but it has things a little the wrong way around and this was corrected in their "RUBY" version....here are the links to both:

LITTLE GEM

RUBY

The circuit I 've been using is pretty similar to the Ruby from the volume control to the right (that is I don't have the pre-amp buffer transistor section). As the EMG's are already buffered by their own preamps it's probably not nececarry either. I do have the 100uF cap between the power supply and ground (just after the 9v+ on the Ruby circuit) and usually a diode for power protection (in case the battery is put in the wrong way and especially if I were to do that with a mains powerpack) wired with it (+ to gnd) and an LED and suitable resistor to tell when it's on. I've also done away with adjustments on the LM386 gain (set by a resistor between pins 1 and 8...ie the top two pins) Wiring the two directly (no resistor) preferably through a 10uf cap to (to help avoid high frequency oscillation) gives a 200x gain (ie maxed out), the sensitivity or gain is controled by the pot on the input (10k) after the preamp (or straight from your EMG's Tim)

Anyone whose been following this in recent months will know I've been having trouble with getting a suitable preamp together of my own design....grrrrr...but in the meantime have had a lot of success with a simple kit bought, 2 transistor, preamp. The main purpose of the preamp is to avoid loading down my pickups and destroying tone and output when the sustainer is switched on, but the pre-amp also to give a hotter signal than my tinny little single coils will provide. EMG's and people with active boosters and the like need not have to worry about the preamp I suspect.

So before leaving, here is a link to the makers Application notes and Data on the LM386:

NATIONAL SEMICONDUCTOR LM386 DATA AND APPLICATION NOTES

You can check out the PDF file from there and you'll find the 20x 50x and 200x amp (as I've described) on about page five. With any luck this link will take you directly to the complete data and circuit diagrams. You'll also find the effects of various loads (eg 4,8,16 ohm speakers/drivers) on the power and distortion levels if you want to get right into it and other stuff besides. Anyway, for less than $A5 in parts your looking at a pretty cheap and simple little experimental/test amp. With this, you'll be able to test and re-test any number of drivers...as I have done.

So don't get freaked out with the electronics and perhaps even scour about the electronics shops for something with the LM386 at the heart of it. I found something in Australia and a preamp kit that works for me. As I recall I found something from a place called Hobbytron, I'll just see if I can get some links for this...

pre-amp / LM380 Hobbytron Kit

More than enough power from this baby but I don't know what power consumption is going to be like. I'd give it a go but this Canadian Company won't export except to the USA!!!!!!!!!!

A-ha...this is more what I was looking for (perhaps someone with better eyesight can confirm if that is in fact a LM386 chip on there).

CANAKITS PRE-AMP/AMP KIT

This has got some kind of buffer/pre-amp and a power amp stage. If they've limited the gain with a resistor, replace it with a wire link or 10uF cap (if it's not already there) for max gain and all your electronics is there. If one of you kind fellows over there can work out a way to get me one (I'll pay...htere's some other stuff they have including a delay that looks interesting) I'd be really interested in hearing from you. If it's suitable it may help get the DIY sustainer down to a fine little gadget without having to fret about all that electronics crap. At $US10.50 you're getting the whole thing with the printed circuit board. Possibly there may be some simple substitution of a resistor here and there to get a better performance for our purposes, a better pot than the little trimmer that they've got and you don't need the socket if you hard wire it but I dare say it looks like just the ticket (why they won't sell it to me down here in Oz and I imagine elsewhere also, I've got no idea!?).

So, there's some food for thought and a bit of detective work for you, and, as I say, if there's a way to get around this export business, I'd be happy to by the thing (apparently my money's not good enough) test it and modify it if necessary so that at least there is a proven option for people who want to get themselves a sustainer or even go further and try and improve on it, if only a little!

Good to be back

psw