zfrittz6 Posted November 9, 2006 Report Share Posted November 9, 2006 This is my new amplifier 1 watio, uses tba820. this is my preamplifier, 3 band equalizer. this is the following thing that I am going to verify if it works well, 1-single amplifier of 1w. 2 - if it does not go with the preamplifier and equalizador well. Link to comment Share on other sites More sharing options...
zfrittz6 Posted November 9, 2006 Report Share Posted November 9, 2006 as soon as my project of the coil in horseshoe form finishes to see as it works, also I put some photos now that I am winding it. Pete, this was what I queria to explain to you with the drawing in post previous. Thus with this form of erradura I try that it has mini EMI to see if it is possible to place the conductor in the average position of the guitar. Saludos desde Fuente Vaqueros- Granada. Link to comment Share on other sites More sharing options...
col Posted November 9, 2006 Report Share Posted November 9, 2006 as soon as my project of the coil in horseshoe form finishes to see as it works, also I put some photos now that I am winding it. Very interested to see how this turns out - I have some sketches of the same 'horseshoe' idea, but I couldn't come up with a practical way to construct it that I thought would work out.... how to setup the magnets was the biggest issue, but there is also the problem of winding and potting evenly on a curved bobbin. good luck, Col Link to comment Share on other sites More sharing options...
psw Posted November 10, 2006 Author Report Share Posted November 10, 2006 OK...zfrittz6, that's a very interesting idea you have there with the horseshoe driver...the circuits look good too but could be a bit big for some and a little concerned about battery consumption... In some ways that driver is a cross between the side and rail drivers...difficult for me to anticipate the effects on EMI and such in my head...will have to see how it runs...very well made BTW curtisA, I re-posted your clip on the sustainer sounds page too so it won't get lost in the thread... Hey guys, long time (and about double the amount of posts there were last time I looked!). Could you possibly do a lowdown on the current state of neck sustainers? It would be handy to see where they stand. Good idea...here is the state of play and where we are heading... There are three major elements to the sustainer project...driver, circuitry, installation The Driver... Several people have made sustainers based on my thin coil principle including myself (on a strat), curtis (on a single coil) and Primal (on one half of a humbucker) and there have been a few more... The thin coil principle is the idea that to get a fast response and low EMI, enough to get a good sustainer response on all strings and fretted notes with simple amplification, a thin coil around a thin core is the approach that I have tested and advocate. The thin coil design was developed by me and consists of a 3mm deep coil around a thin core (3mm wide steel) with a magnet below (or the core is the magnet) wound with about 8 ohms of 0.2mm wire. You could build such a driver on top of a single coil pickup as curtis and I have done or around a bobbin blocked up to 3mm with individual poles (as Primal has done and bancika is in the process of doing)...other's have made the device as a stand alone driver. In more recent times, dual coil drivers have been advocated with col having a working rail style, HB like, driver. The idea is that it will emmit equal and opposite EMI and so cancel it out to some degree and limit the interferance to the pickups. Other styles have been suggested to limit EMI including side coils, bi-lateral coils and now a horseshoe coil....magnetic sheilding and a range of other strategies could also be explored to limit EMI... The driver sits around, replaces or is incorporated into the neck pickup. The reason for this is to create enough distance from the source pickup (the bridge) and will only operate with this pickup. The circuitry... This typically consists of two parts, a power amp (usually using a LM386 amplifier chip of about .25-.5 watts as it is simple cheap and easily available and can run off batteries quite happily) and a preamp. The main purpose of the preamp is to prevent loading and a simple circuit that meets the requirements for our purposes is the Fetzer Ruby combination of simple preamp and 386 poweramp. Loading will rob power and tone and is caused by an impedance mismatch...the pickup is trying to run two amplifiers and is much higher in impedance than the LM386 wants...so the preamp helps condition the signal for the poweramp to drive the coil. In more recent times, col and curtis amoungst others have been seeking ways, by electronic means, to "condition" the signal further to improve response. The feed-forward compressor idea is an attempt to adjust power so as to compensate for the different distances the string vibrates at in relation to the driver by fretting notes along the fretboard. A note fretted on the 20th fret will virtually be touching the driver and respond instantly, where as an open note could be 5mm away and respond slowly. This is related to the "action" of the guitar with a higher action guitar suffering more from these effects. Even though this would make an important improvement, the present basic sustainer with it's simple circuit and thin coil will give a very good performance as witnessed by clips by myself and curtis more recently. Installation... This is trickier than it may seem and varies with each guitar and setup. The main problem is that if there is more than one pickup, any other pickup (neck, middle) will have to be completely disconected and the bridge pickup selected. It is not enough to lift or short out the coils...the guitar's whole circuitry needs to be bypassed. To enable this on curtis's 2 pickup guitar required a 3PDT switch and on my strat a 4PDT...a single pickup guitar would only require a SPDT switch to turn on the sustainer's power. So, this will require a complete rewire of the guitar in most cases and may even require more poles on a standard strat's wiring...more poles, bigger more expensive switching, not too good. The other switch you will want is the harmonic switch. This simply reverses the driver wires running the sustainer in reverse. This suppresses the note causing harmonics to be driven. This requires a standard DPDT switch. More recently we have been seeking ways to have this switch located at the start of the signal chain like a phase switch...curtis has worked out something that may make switching easier for this built into the preamp section. The other control that is typical is a sensitivity control. This is a pot between the preamp and amp to control the gain...I have not found too much use for it, though I have one, and could be easily incorporated in a set and forget trim pot inside the guitar. I do find that a LED indicator is useful, but again, this is optional. Problems with the DIY sustainer... There are 3 main problems. One is universal to all sustainers, the higher, thinner strings are harder to drive due to their low mass...you will need to use 10 guage strings or higher. Second, while switching on and harmonic mode switching is silent, switching off will cause an audible pop or similar sound at present for most people. Third is a slight "fizz" like distortion on very clean settings. This is effectively masked by any overdrive to the signal and is assumed to be cause by some kind of EMI effect. Summary... So, the basic driver in the neck position will give a good performance but not technically perfect...it is still extremely useful and if you use even a mild overdrive in your sound, don't turn it off and use thicker strings will give a very good account of itself for very little outlay. It will mean extensive modifications to a guitar and you will have to DIY and overcome problems unique to your own application of it. We are still seeking solutions, improvements and alternatives to this basic design and I expect there will be breakthroughs down the track. That should not put people off making this device. A new preamp or improved driver could always be swapped out latter if it is warranted. Other stuff... The summary you quoted is the next stage that I'd like to work on...the mid-driver. This would suit strat type guitars and replace the middle pickup with a driver. If this can be done you would retain pickup choice and simplify installation...you would likely get an improvement in action response effects as well. This would require a much better driver design however. I would also like to incorporate the poweramp into or closer too the driver itself and so making the device more modular. This would aid in keeping the driver leads (another source of EMI) out of the main body of the guitar and make the circuit board (only a preamp) much smaller. This will require still more experimentation to see if this will work and how that could be done. One development that has taken place is a method of making bobbinless, coreless epoxy coils with a very simple jig (thanks to Tim/onelastgoodbye)...this means we can make various coil designs and experiment with different cores, orientations and the like to limit EMI and make better drivers. Spazzy has taken a completely different approach by using a conventional rail style pickup driven by a small outboard mains powered PA amplifier. Others have expressed a desire for ebow like sustainers. All of these things feed off one another and create more development...very slowly. My work on a mid driver, even if it were to fail, would still provide improvements in driver design and circuitry implimentation for the neck pickup. So...that is pretty much where we stand at present as far as the sustainer project goes and a little of what the present discussions are about. I welcome you back and all those who are following the thread so loyally, or just looking in from time to time... pete Link to comment Share on other sites More sharing options...
psw Posted November 10, 2006 Author Report Share Posted November 10, 2006 This is my new amplifier 1 watio, uses tba820. This is an interesting alternative to the lm386...more power, low drain...a little trickier to get but relatively cheap and a small circuit...it would be interesting what others think of it. I notice for instance that the load can be tied to the positive rail instead of the ground, perhaps addressing a few issues there (pop and fizz?)... I quite like the idea of more power...I am thinking more headroom and simpler preamplification in an attempt to run the thing cleanly. I am still looking for alternatives to the LM386 but as this is still a DIY proposition, we should still be seeking for low cost and ease to build the thing...proof of concept aside, there would have to be a good reason to seek anything too exotic. Meanwhile...I have been having some fun playing the guitar today...it really does inspire me in different directions musically. I am hoping that after I move I can have more music in my life and do a bit more composing and recording of some real music, not just clips... It will be interesting to see as more people take this on what musical ideas come of it...it may simply add flavours to your present style or could become the basis of a unique voice in of itself. I can't wait to see where this thread leads us, summing up in my last post I realized how much, yet how slow the progress may seem, but it does take time for ideas to reach their fruition. The thin driver idea came suddenly but not until a lot of time and effort went into following other routes. Col is on the right idea with his action compensation circuitry, curtis has now a working guitar as a basis for improvements, bancika is about to build a discrete driver and innovative ideas are coming from zfrittz6 in driver design too. Spazzy reminds us that there is more than one road to travel and onelastgoodbye has brought into being a wonderful solution to the making of solid coils that are stripped to their essence. And, let's not forget all those who are simply visiting this thread and in so doing encouraging us all...over 200 visits in the last day! Thanks to all. In a few weeks I will be off the net for a short while, while I move. There is and will be much to do but I trust people will still be chipping away at this project for a while yet... pete Link to comment Share on other sites More sharing options...
bancika Posted November 11, 2006 Report Share Posted November 11, 2006 Hi guys, I'm back. Finally got a camera to take a few pics of progress. I finished winding my first driver, coil is potted with transparent glue. Leads are also glued to bobbin. Link 1 And a photo after it's covered with insulating tape Link 2 You can see here that I set pole pieces for lower three strings a bit higher. After I test it I'll re-align them if needed. What do you think about it so far? One idea for dual coil design. What about taking two winding wires together and wind them together. After winding enough (half of turns needed for usual one wire winding) just solder oposite sides of coil together. Maybe someone suggested it before Cheers and thanks for help. Link to comment Share on other sites More sharing options...
Roobin Posted November 11, 2006 Report Share Posted November 11, 2006 Wow, Pete! That's really answered my question! Thanks for rounding up all the info - you've saved me (and hopefully others) a lot of time. I don't think that progress is slow, though. It takes time for people to make things, come up with ideas, etc. I think it's all been stunning. As you've said, you've got all these different driver designs, amplifier designs, now people are changing the position of their driver...try keeping up! BTW Good luck with the move, Pete. Link to comment Share on other sites More sharing options...
psw Posted November 11, 2006 Author Report Share Posted November 11, 2006 What do you think about it so far? Link 2 One idea for dual coil design. What about taking two winding wires together and wind them together. After winding enough (half of turns needed for usual one wire winding) just solder oposite sides of coil together. Maybe someone suggested it before That looks great, very well made, I knew that wire was going to a good home! Some ideas are so good that you wish they would work from will alone ...however... One of the interesting things about this project is that it makes you think about things that we tend to take for granted in our everyday world...like the subtlties of electromagnetism. So...a coil of wire will make an electromagnet when a current passes through it...actually a straight wire will, it is the overlapping wires that build upon one another that factors into the strength of the field. Hence, I found that the thin coil is ideal in that you get a good number of overlapping wires...winding the full bobbin with the same amount of wires will not produce the same effect. Now, in your proposal, you would have wires putting out equal and opposite magnetic radiation, right next to eachother and I suspect the end result would be cancellation of the electromagnetic effect. This would cure electromagnetic interferance (EMI), but also prevent the very electromagnetic radiation (EMR) that makes the thing go. Remember, we want to optimise EMR but prevent EMI...EMI is caused by the EMR getting into the pickups or wiring of the guitar. So, EMR good, EMI bad... An interesting idea may well be to wind a 4 ohm coil, and wrap that in another coil over the top of that wired back to back so that the inner coil is driving the string while the outer coil sheilds the device and focuses that energy. It sounds like a good idea, but may simply suffer from the same effect as your proposal. If these things were possible, we would see such coils in everything from motors to TV's and transformers of all types, afterall. The difference between these ideas and the rail or stacked pickup is that they are wound around a magnet of opposite polarity. They are reverse wound on opposite magnetic poles so their effect is the same on the string while still cancelling out the EMI, at least to a large degree. So, in your idea, you have two coils, at best, working in the same magnetic field in opposite directions, cancelling each other out. To further illustrate this, consider a stacked coil. The north end has one coil, the south another wired opposite. A current passing through these coils will make the north end stronger and the south weaker (and a current in the opposite direction the opposite) and so enhancing the effect. Hope that helps a little in conceptualising ways to address the EMI problem and focusing the EMR effect. The dual coil cancelling ideas are one approach mind you, orientation of the coil(s) is can also have a big effect. The magnetic radiation can couple to another coil causing EMI by the amount of radiation that passes through their cores. If one coil is tipped 90 deg to the other (as in a side coil) the bulk of the radiation will be entering the pickup through it's side and so not be so coupled to each other. There are a lot of different orientations possible in 3D space that could aid us, but one must beware with all of these things that the driver doesn't loose efficiency, require more power and so not just put out more radiation that will eventually stray into other coils anyway... Wow, Pete! That's really answered my question! Thanks for rounding up all the info - you've saved me (and hopefully others) a lot of time. BTW Good luck with the move, Pete. I hope this stuff does help, or at least get people thinking. It is often a good idea to summarise and take account of where we are at and bring it back to the essentials. It may well be that a simple single coil driver is the most effcient, on balance, way of making this device. I would like to think though that more could be done and that, for myself, the driver could be moved successfully. There are still a few ideas that have not been tried to address the two main problems with the present device..the pop and fizz. If these, especially the first, could be adequately addressed I would have no hesitation in promoting this device even more and providing more access to circuit boards or kits. As it stands, it is not quite right. Col's ideas may make a good thing even better, it may well then surpass the commercial units performance in combination with a thin driver or his thin dual rail idea, but even without it, it is a worthwhile thing and pretty simple. The mid driver is ambitious but will stretch things a little further as far as driver design and construction. Different amplifier options may well address the pop and so, even if we must still content ourselves with a neck driver due to EMI or performance issues (how well the string drives, unexpected harmonic effects, and the like)...there will be some improvement gained in the process I am sure.... Still, there will be a long wait...personally I have a lot on my plate and I really will need to get stuff together on the domestic front. That said, there is a lot of time that I have waiting and missing my children when keeping busy and distracted is the best therapy and for that, I thank you guys for that in this thread...sometimes it is better to think of coils and such than the pressures of real life, think of it as meditation pete I heard an interesting quote somewhere... give a man love, if you can't give him that give a man hope, and if not that at least give a man something to do with his hands... Stay busy... p Link to comment Share on other sites More sharing options...
bancika Posted November 11, 2006 Report Share Posted November 11, 2006 That looks great, very well made, I knew that wire was going to a good home! Some ideas are so good that you wish they would work from will alone ...however... One of the interesting things about this project is that it makes you think about things that we tend to take for granted in our everyday world...like the subtlties of electromagnetism. So...a coil of wire will make an electromagnet when a current passes through it...actually a straight wire will, it is the overlapping wires that build upon one another that factors into the strength of the field. Hence, I found that the thin coil is ideal in that you get a good number of overlapping wires...winding the full bobbin with the same amount of wires will not produce the same effect. Hi, did you reffer to my coil? It's not winded all way, just 3-4mm Cheers Link to comment Share on other sites More sharing options...
bancika Posted November 11, 2006 Report Share Posted November 11, 2006 (edited) one more thing about "concentric coil design" what about making inner coil much larger than the outer coil. It would have enough power to drive strings and outer coil would keep EMI down. In my case, for instance, it would be 100 turns inside and 12 outside. Edited November 11, 2006 by bancika Link to comment Share on other sites More sharing options...
psw Posted November 12, 2006 Author Report Share Posted November 12, 2006 did you reffer to my coil? It's not winded all way, just 3-4mm No...you have done it as suggested...but if you had have wound the thing on the whole bobbin it wouldn't have worked one more thing about "concentric coil design" what about making inner coil much larger than the outer coil. Well...without trying it... I would expect that the outer shield would create an "active shield" but it would still be around the same magnetic polarity and lower efficiency. One solution may be to wind a coil, put a thin metal shield around that, then wind another coil around that..perhaps magnetise the inner sheild to the opposite polarity...it all gets a little complicated and difficult to construnct comapred to a stacked or rail design for much the same result I suspect. I think a stacked coil would have some significant improvements...you would need a short magnet I suspect and perhaps two 2mm deep 4 ohm coils. The opposite magnetic energy may actually push the power of the top coil a little more, or at least have a similar effect to the single coil. I still have some reservations about the rail design, a lot of it's energy is passed between the blades themselves, lines of magnetism through the sides of the coil are effectively wasted in sitring driveing energy I suspect... It does work as col has shown, so I may not be right in my thinking. The bilateral driver may have some more promise, certainly I am sure all these kinds of variations were tried by sustainiac and it works for them, dizzy made a successful mid driver with a similar thing. If we were to combine the bilateral with the rail design, the thin coils and cores of my designs, we might have a winner. The hex drivers used every strategy at once, magnetic shielding, multiple magnetic elements, orientation...but perhaps I went too far, I'll be holding out for something simpler... pete Link to comment Share on other sites More sharing options...
bancika Posted November 12, 2006 Report Share Posted November 12, 2006 What about winding directly to magnet. Those magnets salvaged from pickups are approx 60x10x5 mm, can I just use them as a core. I'd like to build one blade prototype and do side-by-side comparison with discrete driver on same amp circuit. Link to comment Share on other sites More sharing options...
psw Posted November 12, 2006 Author Report Share Posted November 12, 2006 That's a good idea... However, one theory that I have is that a thin core will be better. The reasoning is that a wider core will span the nodes of the vibrations especially on the high strings and so driver and dampen the string...hough I have no proof of this..10mm wide does seem quite a bit. On the otherhand, sustainiacs driver uses a wide core, but then the thin coil/core are the main differences in my approach to other proposed sustainers and is the main thing that I have brought to the table I guess as far as this technology goes. Tim/onelastgoodbye made one of my favorite drivers... Cutting a magnet is ill advised however and never try to cut or grind a neodyminium magnet, very dangerous. A better bet would be to search out some craft or other source of small magnets. These are often sold in craft shops and even some electronic shops for fridge magnets and also in things like those magnetic letters kids stick to fridges and stuff. You also find them in magnetic "pins" to stick to white boards. These are small ceramic discs and you could put a row of them together to make a core. Suitable magnets can be a bit tricky to find, especially for some of these more specific designs. There still may be some use for neodyminium magnts, but possibly not in the core of conventional drivers...all the hex designs used neo-mags, but not pointing at the strings! You can use them under a blade, but a normal pickup magnet seems to work better...to get a similar power, you are talking a very much smaller magnet and it's lines of magnetism, although very powerfull, are very much drawn to their own opposite polarity...so small is not always better in this regard...at least with conventional designs. I could see neo-mags being used potentially in rail designs and possibly on deep blades (far from the strings) which would change the shape of the magnetic field... Hold out for a more suitable magnet I suggest. Interestingly, Tim's epoxy jig thingy would work with a core made of multiple magnets as the wires could pass between them and the core need not be removed. I would suggest making a line of mags and filling the gaps with putty to make a core, then wind on that... pete Link to comment Share on other sites More sharing options...
bancika Posted November 12, 2006 Report Share Posted November 12, 2006 No, it's 10mm high and 5mm wide. I'm not sure wat are you reffering to with "width" It's thinner than tim's core, but taller. I have one core that's about 5x5x60mm (from one of pickups I got), which is very close to tim's just a bit smaller. Maybe it's a better choice. Cheers Link to comment Share on other sites More sharing options...
psw Posted November 13, 2006 Author Report Share Posted November 13, 2006 Ok...most single coil mags are that dimension, like the ones I use...perhaps yours is from a humbucker. It is all to do with where the poles are... | - N - | | - S - | or | N - S | which could also be | N | | S | By width I mean the part of the core that faces the string and around which the coil is wound. The 5x5mm would make an excellent stacked pickup I would think...if you were thinking along those lines...perhaps 2x 2mm 4ohm coils around it...that is a rare find Just so everyone is on track, my idea about the thin core is that as the string vibrates, one part goes up and the other down and passes through a "node" or zero point. It does this for the fundumental and other modes of vibration that make up the harmonics. The characteristic "tone" of a guitar is the way in which the wood and construction effect the mix of these harmonics and on the ability of the pickups to sense and amplify these vibrations. Higher notes move faster and have a shorter wave length and so these zero crossing points between the up and down swings of the string are closer together The sustainer circuit takes takes a reading of these vibrations from the bridge pickup and amplifies it and sends it to the driver. The driver's coil will then alter the strength of the driver's permanent magnet pulling stronger or letting go causing the string to vibrate. As both the pickup and the driver are fixed, it is possible that the driver could sit under one of these zero points, or a wide core to straddle both the up and down swing of the string dampening the vibrations. If completely reversed, as in the harmonic mode, it does completely dampen the vibrations causing the background higher harmonics (which have different nodes) to be sounded...just like using a light finger at the twelth fret to sound natural octave harmonics on an open string, you ar dampening the fundumental note. Often the note is not the octave as this to may be dampened so the next harmonic, a natural fifth or even higher will emerge and be sustained. So...my conjecture is that a thin core is less likely to exist at the zero point and certainly less likely to straddle both the up and down swings of the string. This is particularly likely on the notoriously high strings which are already hampered by lower mass (they are thinner and so have less steel in them), higher tension and faster vibrating speed. A wider core may move the lower strings more effectively, but it would seem that a less efficient drive is warranted on the lower strings which are far easier to excite, to achieve some balance. You can make the core too thin though as the coil does need something to work on and to transmit the magnetic field through the core. I use a 3mm steel core that is easy to obtain, but this is not specified. It is possible that an internal magnet may work better and withstand some more width...typical blades in a rail pickup (perhaps 1.5mm) may be a little too thin, I don't know, yet! Part of my reservations about the rail design is that the two blades combine to make an effectively wider coil, but then col's works! All these are just ideas, perhaps theories, hardly conclusive...sustainiac's core is wide, so my thinking may well be faulty. There are plenty of options and I am sure other ways than my thin driver design that will work. For now, I'd get this design that has proven to be effective to work, get the circuit happening then make whatever designs you choose with whatever you can get your hands on. The single coil driver looks fantastic I cant see any reason for it not working as well, possibly better than mine or curtis's recently finished one. For instance...my very early hex designs were effectively six small 1.2 ohm coils under each string. Everntually I sought to make them tailored to each string's response by altering the number of winds. Making such coils is fiddly and six times the work of course, but for a dedicated driver, you could reverse the polarity of each magnet and coil to help limit EMI. Eventually I discovered another way of creating the electromagnetic effect without having to wind the coils and developed ideas using multiple magnets, orientation of the forces, magnetic shielding...most of which has been eluded to throughout the thread. I would not necessarily encourage this however, there are problems that can arise as to the alignment of the strings, so that in the least, string bending can course problems. Also, the components were not esy to obtain and had some degree of failure...I have 100 of them somewhere as I had to buy them in bulk just to experiment...so not really DIY freindly at all. But, some of these strategies may well work with a conventional coil driver... Here is the rail driver from a kramer guitar that spazzy has mentioned previously... Notice the metal "shield" on the pickup side of the device...experimenting with such things may well be rewarding enough... All of my ideas are up for debate, I know I am a little on shaky ground with them. All I can say for certain is that it will work with the thin coil, core and 0.2mm wire if well potted. Just about anything will move the low strings, but the high strings are the difficult part. The wire is important and I did try various different thicker and thinner types with less success...this has been bourne out by others. I have made some a little deeper (5mm) that worked ok and with individual poles (the blade is not essential) I am not sure if even thinner (col's coils are 2mm) is better or worse, I am not sure if the rail, bi-lateral, side or stacked drivers are going to be a significant improvement...but there is certainly scope to combine ideas and strategies and in doing so, I hope the mid-driver will be achievable without getting too fancy with the construction. As for the circuit...a lot of interesting stuff has come up. Col's work on the compressor, but most of all pointing out the problem of action (not high strings or even high notes) as being an issue, is very instructive. There are certainly a few amp options and preamp ideas to try out yet as well. Fixing the fizz and the pop are essential even whatever the driver, so these too will have to be addressed ASAP!... pete Link to comment Share on other sites More sharing options...
bancika Posted November 13, 2006 Report Share Posted November 13, 2006 Yes, those large ones come from two coils of humbucker (the cheap one) and smaller ones are also from other humbucker, just magnet on one coil was missing. I'll ask a friend who gave me pickups if he still has it, if he has you can have it I'll have to make a bobbin (have nice sheet of 1mm plastic that I got by mistake for pickguards, it cuts really well)..and I'll probably try stacked design. It can be only better, right? Link to comment Share on other sites More sharing options...
psw Posted November 13, 2006 Author Report Share Posted November 13, 2006 A stacked coil was the pickup that Micheal Brook used on the original "infinite Giutar"...I never quite understood why this was not continued into development with sustainiac and fernandes's various models...certainly it looks like a very promising approach...not applicable to the pickup/driver idea, but as a stand alone driver, it could still be made pretty small and at least as easily as a rail or other humbeucker design.... Let's get the driver you have made working...get the whole thing working outside the guitar first and takle the installation later... good luck... pete Now it's time for sleep... 4am start tomorrow... BTW, the weather here is odd. Melbourne is notorious for changing weather...yesterday was hot and humid, today cold and windy...and a little rain, but we are in the worst drought for 1,000 years (7+ years so far) and we never get enough... I prefer the cold for work, when it is hot, it get's very hot! Link to comment Share on other sites More sharing options...
bancika Posted November 13, 2006 Report Share Posted November 13, 2006 I just got back from the store getting all remaining parts for amp circuit. Hopefully I'll have some kind of result tonight Cheers Link to comment Share on other sites More sharing options...
bancika Posted November 14, 2006 Report Share Posted November 14, 2006 RESULT I finally finished soldering amp. First I tested it with speakers to make sure it's working OK and I've got little confused. When I set bias for JFET to anything above 3.5V it hums like hell and guitar sounds like it has some kind of ring modulator/octaver effect. At ~3.5V there isn't hum but still a bit of octaver thingy. Reducing drain voltage to ~2.2V solves it. I tried another JFEt and it was the same. Anyone with the same expirience? Then I hooked up driver and tried holding it in hand above strings at about 24th fret (that's where it will be on squier) on my main axe (non-suspecting squier isn't around). Little messing with trimmers (gain and volume) I got some kind of result! Because I used guitar cable to connect to fetzer/ruby I couldn't plug it to amp and hear what it sounds like there but "dry" test went pretty well. Both modes work fine. Even high E string vibrates infinitely. How do you guys set gain and volume? I set mine to 50% gain and 100% volume. It's just a test, when I install it probably it will be somewhat different. One more weird thing: when I press my ear to driver I can hear it humming. When neck pickup is active it also wistles in high pitch. Maybe it's because it's near neck humbucker? Cheers and thanks for great project Link to comment Share on other sites More sharing options...
col Posted November 14, 2006 Report Share Posted November 14, 2006 RESULT I finally finished soldering amp. First I tested it with speakers to make sure it's working OK and I've got little confused. When I set bias for JFET to anything above 3.5V it hums like hell and guitar sounds like it has some kind of ring modulator/octaver effect. At ~3.5V there isn't hum but still a bit of octaver thingy. Reducing drain voltage to ~2.2V solves it. I tried another JFEt and it was the same. Anyone with the same expirience? Yep, I remember setting up the fetzer/ruby and not being able to get the bias anywhere near the 4.5v I was trying for. I was assuming that 4.5 was the target because thats the usual figure in fet stomp boxes... it ended up at about 2.2v as you say.... Then I hooked up driver and tried holding it in hand above strings at about 24th fret (that's where it will be on squier) on my main axe (non-suspecting squier isn't around). Little messing with trimmers (gain and volume) I got some kind of result! Because I used guitar cable to connect to fetzer/ruby I couldn't plug it to amp and hear what it sounds like there but "dry" test went pretty well. Both modes work fine. Even high E string vibrates infinitely. congrats Now the real 'fun' starts How do you guys set gain and volume? I set mine to 50% gain and 100% volume. It's just a test, when I install it probably it will be somewhat different. One more weird thing: when I press my ear to driver I can hear it humming. When neck pickup is active it also wistles in high pitch. Maybe it's because it's near neck humbucker? set the vol and gain as low as you can while still getting acceptable results. As far as the 'singing' driver, I got that at first - others have noticed the same thing, I think its just a sign that the vol/gain are too high. The whistling is parasitic feedback caused by the pickup sensing the driver directly instead of via the string - something to avoid.... you have to keep the driver as far away as possible from any in-use pickups. In Other news... I finally got around to breadboarding my version of the Fet attenuator - results are very good. Fizz is almost completely gone, and I have a hunch as to why. The circuit I'm using is based on a combination of the Fast Peak Limiter circuit and the Improve FET Gain Control circuit. I used the Fet circuit from the Fast Limiter because there is very little distortion and it can be set up so that the response stays linear right through the guitars frequency band. Hunch #1 I have set this up so that the agc causes very little distortion above 82 hz. I noticed that when I set it for a faster attack response which causes distortion at lower frequencies, I get fizz at lower frequencies... hmm Also, I checked my LM13700 based circuit, and right enough, It has loads of asymetric distortion particularly (but not exclusively) at lower frequencies... (not hard clipping, more of a soft fuzzface type and funnily enough a fuzzface style fizz). There seems to be some slight fizz noticable during transitions... after you hit a chord hard and it starts to fade, there is a little fizz as the sustainer kicks in - furtunately when the circuit reaches an equilibrium, it cleans up again... This may just be my amp sim though - my pickup is too hot for it :-|... I really need to test with some other kit that can produce a predictable clean tone with plenty of headroom... So it _may_ be that if the driver signal is in phase and has little or no distortion, any bleedthrough/crosstalk is unnoticable because it is nearly identical to the guitar signal. Hunch #2 it just pure luck Anyway, I got my positive vibe back again The current drain is back up to about the same as my first agc circuit ranging roughly from 35 to 60 mA... 13mA at rest. It's back up a bit because I boosted the volume so that the effect isn't so subtle. I incorporated a phase reversing stage (uses a SPST) for harmonic mode - this causes some squeal when you damp the strings, but that should be fixable by getting everything set up just right... gain, sensitivity etc. There is no through buffer so if the battery goes dudd, you don't lose sound. The circuit uses 6 op-amps and an LM386. so either 3 dual op Amps or 1 dual and a quad. It might be possible to replace a couple of the op-amps with transistors, but it probably wouldn't make the board smaller, and would almost certainly make the thing work less well. Just for the record, I'm using my dual rail driver with no shield. it is connected via about 50cm of home-brew 'inter-8 weave' cable This new circuit does a superb job of fundamental mode sustain - chords are great and single notes and/or harmonics sustain very well accross most of the neck... The maximum output volume is controllable via the threshold knob, although I may just keep that as a trimmer. there are still one or two frets on the high E string that go to harmonics because the just don't want to play ball... I still need to work out a simple and good 'mixed mode' to get a good harmonic bloom without going into full harmonic mode. I guess this will just be some switchable filter caps in the right places, just not got around to that yet. When thats done, I'll post the schem. @pete I tried to get a power off 'thump' by just pulling the power supply lead from the plugboard. No thump, just a crackly click... probably the click would be gone if i used a proper switch - will try that soon cheers Col Link to comment Share on other sites More sharing options...
psw Posted November 14, 2006 Author Report Share Posted November 14, 2006 Col... Anyway, I got my positive vibe back again That's good, I thought you were getting a little disheatened... I think head room is a potential issue, I'd like to get a little more into an alternative amp perhaps to address the problem too. There may well be more to the phase issue, we have not discussed the relative phase of the signal being picked up by the bridge pickup in relation to the position along the driver of the string.... Sounds like a good result...at the very least it seems to be addressing some of the issues you have identified. bancika... Then I hooked up driver and tried holding it in hand above strings at about 24th fret (that's where it will be on squier) on my main axe (non-suspecting squier isn't around). Little messing with trimmers (gain and volume) I got some kind of result! Because I used guitar cable to connect to fetzer/ruby I couldn't plug it to amp and hear what it sounds like there but "dry" test went pretty well. Both modes work fine. Even high E string vibrates infinitely. congratulations...you appear to be well on track...if not a total success! The driver should only physically hum if there is any give in the windings...it can take a while for the glue to really set in and the windings to settle down...it may improve...the winding looks pretty good by the photos. When neck pickup is active it also whistles in high pitch. Maybe it's because it's near neck humbucker? Yes... There is no way to have the driver anywhere near an active pickup and both me and curtis have found that it is not enough to simply deselect the pickup in installation (if there is a neck pickup or driver pickup) but to lift both ends of the coil)...you have coupled the neck pickup and the driver magnetically and effectively made a transformer...any loose windings in either device will try to vibrate.... You will also get massive gain and distortion from this transformer effect which is at the heart of these problems. Now you can see the difficulty in the mid driver concept, how close can you go without these effects overwhelming the system! You will find the actual guitar a lot better...you may have to do something tricky to bypass the middle pickup. It could be worth removing both the mid and neck pickups and trying the driver in both positions to at least see if it is possible Nevertheless, like curtis, you will find that an actual installation will improve things. I would test it with an amp though to look for loading effects and keep tweaking the amp...perhaps you don't need quite as much power as you are putting out and could trim back on that...saving the battery life in the process. Sounds like another successful sustainer is well on the way, looking forward to pics and clips and future developments from you and curtis. Once it is finally installed though, you may have too much fun playing the thing to want to change it further, even in it's basic form, for all the fizz and pop, it is an impressive device. Hope your progess will inspire others to give this a go... pete Link to comment Share on other sites More sharing options...
bancika Posted November 14, 2006 Report Share Posted November 14, 2006 tnx guys. I hope pics and clips will be ready soon next up is new driver with that magnet I have with stacked coil. I'd like to compare them before installing. One question.If I wind both coils in the same direction I should connect both starting leads (or both ending) together to get humbucking mode? should I just solder then together on bobbin without making wire taps? Cheers Link to comment Share on other sites More sharing options...
col Posted November 14, 2006 Report Share Posted November 14, 2006 I think head room is a potential issue, I'd like to get a little more into an alternative amp perhaps to address the problem too. There may well be more to the phase issue, we have not discussed the relative phase of the signal being picked up by the bridge pickup in relation to the position along the driver of the string.... Headroom in the driver circuit seems fine - I've actually taken advantage of the limited headroom provided by the 9v/opAmp situation, I've set it up so that any input signal above around 300mV will be clipped in the input stage (well above the top threshold), this is to put a cap on the maximum through signal. maximum attenuation of th FET is limited, and without this clipping, louder signals > 400mV were being amplified close to the level of the desired 'correct' signal. The Headroom issue I am having is not sustainer related. When I plug my guitar directly into my RunOffGroove Condor amp sim, it doesn't have enough headroom and louder playing causes clipping. This means that I can't be sure that the fuzz is being caused by the driver circuit or the amp sim. In my earlier circuit, it was definately the sustainer, because it happened more in some quieter passages. The phase issue you're talking about won't have an impact on the crosstalk noise 'masking' I mentioned. What it does seem to do though is lengthen the attack part of the sustainer action. Some notes fight more than others before relenting and allowing themselves to be sustained. Sometimes theres a little dip in output as the sustainer takes over from the natural string vibration - I think this is caused by the phase difference between the driver position and the pickup. If the signal at the driver gets close to 180º out of phase with the pickup, we get the harmonic mode effect, I find this is most noticable on the high E string - maybe because it is such a wimpy weakling and can't put up enough of a fight The only way to improve this is to have the driver closer to the pickup. The issue will still exist, but it will probably not have so much impact because it will effect higher frequencies. It may be that with a good enough 'crosstalk masking' circuit combined with a dual rail (or bilateral) driver and possibly some shielding, we could get close to the holy grail of a mid position driver - if so, this would go a long way towards reducing any problems caused by phase difference between driver and pickups. I remember in my handheld driver tests with the dual rail, as I moved closer to the bridge, the fizz increased, but there was no squealing feedback until just after the mid position... however, handheld above the strings is not the same as fixed beneath, it just gives a rough idea, and the crosstalk noise was MUCH worse nearer the mid position. I still think that a driver in mid position is going to intorduce more problems than it solves - oh, and I don't have a mid position on my guitar My take is that in an ideal world, we could use the neck and/or bridge pickup with the sustainer in order to get a better range of tones. In reality, I would rather have one very clean pure tone than a range of noisy fizzy ones (col attempts to convince himself not to buy a router and attack his guitar... and to be happy with what he's got) cheers Col Link to comment Share on other sites More sharing options...
col Posted November 14, 2006 Report Share Posted November 14, 2006 I uploaded another demo clip to my soundclick page this time its a crappy rock style jam with computer drums... using my runoffgroove distortion box and cab sim, sustainer is in harmonic mode throughout. the clip is called 'rawk sustainer demo'. cheers Col Link to comment Share on other sites More sharing options...
bancika Posted November 14, 2006 Report Share Posted November 14, 2006 Hi, few questions: how should I wire sustainer at all? I tried to make a sound clip of hand test but have a problem. When I wired it in parallel with guitar output on my last test signal didn't even come to sustainer circuit. Only when I unplug guitar cable I get signal coming to sustainer. Weird?! Second, I noticed that when I hit high E string (jn sustain mode) it doesn't sustain but instead G string vibrates in that pitch. I didn't notice that last night. It will maybe be different when I install driver but it's weird anyway. What about phantom powering sustainer circuit using stereo guitar cable. One "stompbox" would be connected to 9V power supply as all other pedals and send those 9V through second "channel" of stereo cord. That would eliminate battery nside guitar. Cheers Link to comment Share on other sites More sharing options...
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