mrjstudios Posted June 20, 2007 Report Share Posted June 20, 2007 Oh, ok. Oh well. I replaced mine with the correct pot', and it sort of works..... still a distorted sound compared to the youtube tests... The reason I built a new one is because although the youtube one worked perfectly at times, it would only do so if I bumped the wires just right. By the time I had moved it around to install it in the guitar, I could no longer "wiggle" it into working, and had no clue as to where the shorts and disconnections were. So I built the new one to the SAME specs, literally built it side by side, but with much better soldering technique, etc., and it works consistantly -- no weak connections. The only problem is its quieter, and more distorted sound. I also hooked it up the XS002 to the amp today and got a few open string sustains (on the 3 low strings, that's it) even with this bad F/R, connected to my single coil driver. It seems underpowered though, and just squeels when you give it enough power to do anything in harmonic mode. Also, I noticed a radio station coming thru as well at certain times, and my cell phone was making it click like it does when I get a call near a police radio scanner.... So any clues as to what may be wrong with the circut (simple wiring problem most likely) that would cause those very specific problems? Link to comment Share on other sites More sharing options...
mrjstudios Posted June 20, 2007 Report Share Posted June 20, 2007 Hmm, how do you get an "avatar" picture like PSW...??... Link to comment Share on other sites More sharing options...
col Posted June 20, 2007 Report Share Posted June 20, 2007 Hmm, how do you get an "avatar" picture like PSW...??... I have a vague recollection that it has something to do with making a donation ? Link to comment Share on other sites More sharing options...
psw Posted June 20, 2007 Author Report Share Posted June 20, 2007 good morning I've been doing a bit of research into a different opamp preamp for this again and will try a few experiments... the correct pot' that shouldn't be the source of your problem...the A/B just mean linear or audio taper (the A type will make it harder to adjust finely)...I take it is the pot between pins 1 and 8...no resistance here is full power, I now run mine with a 10uF cap between these pins and no pot or resistor...one of the mods to the "champ" circuit. ok...so let's back up a bit... I think the F/R is the best bet at a starter-type introductory circut. That was my first real circut build -- and so I looked long and hard for an easier way out, but the F/R was definitely the best bet. This whole circut thing here is definitely a big part of this project as a whole, so lets get a standardized one done NOW!!! (Not making demands, just excited lol.gif ) Ok, here's my proposition.... Lets take the F/R design as it stands: I really think (and think you all would agree as well) that the L386 is the way to go for that stage of the amp. I know many people have objections and are probably right in criticizing the Fetzer valve stage of the amp, but the the L386 is solid, standard, cheap, and works really well. Plus, it is easy to find all over the world -- be it online order or stores. I have not built the F/R...it was proposed by GalagaMike in the tutorial he started. I don't want to sound mean or disrespectful...and I've held my peace for now...but I do think he jumped the gun a little. He only seemed to get it to the preliminary stage that MRJ has done, hadn't ironed out the problems or fully installed it and never really got full sustain across all the strings as mine did. I added to the tutorial my fully working guitar soon after to show the rest of the work that needs to be done. I would much rather he had presented his progress to us on this thread before posting the tutorial so these things could be discussed... While G'mike's work was ok, he did not follow my formula completely (slightly different wire guage, SS core material, wider core. neo-mags oddly placed, high cap in the output stage) and never adressed the problems he encountered (e.g...no harmonic drive). The F/R turned up completely unexpectedly in this tutorial and to this day I have never built it...so I can not check it either. It is however a valid solution for the project and not the source of the problems he encountered. The F/R is a mix of two circuits from RoG. They are minimalist to say the least. The data sheet for the LM386 for high gain (bridging pins 1 and 8) suggests the extra components that I and the ("champ" designer) included to avoid oscillations and such...LM386 Data sheet look at amplifier with gain of 200 circuit. I tweaked mine further to use a 100uF cap to bring out the highs more to get better high string response on my guitar. The fetzer preamp stage has had a lot of builds, but it is designed for "tone"...that is, it is supposed to overdrive a little...is that what we want here? Not at the cost of complicating things with difficult to find Jfets and trim pot biasing...grrr When proposing circuits in the past, people suggested that op-amp designs were overkill and larger with one more component...blah, blah...I know, but these things are solid and foolproof if designed for properly. Unfortunately, circuit design is not my forte...still...this is DIY... Basically...I have never had a problem with the LM386...that is not to say things haven't gone wrong from time to time...I put one in backwards once, used a socket and the thing was not damaged at all by having the power going backwards through it's inputs!!! And minimalist is fine...my first experiments used a LM386 with an output cap, no preamp at all and worked (really, two components everything else is in the chip)...but that won't work for the real thing (loading and such)... Now...I figure a matching IC based circuit just as easy to build and failsafe is the go...but I have an aversion to discrete transistors for some reason...they may "sound better" but that is not required here, otherwise we'd use tubes! A chip like the TL071 or 072 perhaps...is the obvious choice...widely available at least. But...you want to look a little ahead...if the direction I am moving in is the future for this project...you may want the phase reversal built into the preamp stage...this won't become fully apparent till I do it I guess, but I believe there are significant benefits to dividing the two circuits (as col's effectively does BTW)...particularly with mid position drivers and small cavity guitars. Plus, you can troubleshoot each circuit separately! Also, if I were to invest in making something available in some kind of kit form (as I'd like to do, and solve all of these probems) I'd want to be sure that the solution is right. While the circuits I use work for me, I don't think they are "right" or will suit everyone...nor are they the most compact (though not large) for this particular application. So...that has always been my vision...once something is settled on, if ever it were built in SMD form, even col's more elaborate circuit would be much smaller than the present commercial units and more versitile too... I really think (and think you all would agree as well) that the L386 is the way to go for that stage of the amp. yes...and yet... If you separate the power and preamp stages, you can easily swap them out...say build col's preamp, or a different poweramp. I am actually exploring a different poweramp stage with a little more power and a few other features that make it even easier and smaller and does not ground the driver...sure the chip is harder to get, but if I were to supply it...hmmm A poweramp stage like this takes some of the pressure off the preamp, possibly only requiring buffering to avoid loading. Although I am working in this direction, please don't think that the circuit has some magic mojo to it...we are still looking at simple amplification here...the driver is still the key to getting this to work without circuitry hocus-pocus. Today I will try and get a little more work done on the guitar...still doing a bit on the rewire tweaking...that is coming along well...I will try and mount the driver into the guitar (need to make a base plate and wire it in)...and perhaps make up a few circuits. If all goes well (other things may come up) I may be testing the mid-driver in the next few days. If it works, we could explore the circuitry question more and use this guitar as a test bed for these ideas. It could be, that col's circuit or something similar is the way to go if components and circuit boards were available freely...we'll see! Anyway...better finish breakfast and get on with it... pete Hmm, how do you get an "avatar" picture like PSW...??... oh...go to your member profile (click on your own name) and select one or create or download something small enough (perhaps add it to photobucket or whatever) and add it in there. You can add text in your signiture (as I have added sustainer links) in your signiture that will appear on each post...don't add pictures here though... p Making a donation would be nice... Link to comment Share on other sites More sharing options...
Aidouri Posted June 21, 2007 Report Share Posted June 21, 2007 (edited) I was reading about the lack of sustain at High E and B string,the remedy is to adjust the driver closer to these strings right? Then I thought that this changes the position of the magnetic field towards the strings,maybe a slight change but what if the shape of the metal core of the driver was something like this: Could that make things easier? Just an idea... Edited June 21, 2007 by Aidouri Link to comment Share on other sites More sharing options...
psw Posted June 21, 2007 Author Report Share Posted June 21, 2007 I don't think that will help a lot...my strat's driver is completely flat...you will want to adjust the coil and blade closer to the high strings, but there is more at work with the high string difficulty. The main one is the mass of these high strings...there is not a lot of metal for the magnet to work with Also...they are under more tension...they are harder to move Plus...they move faster...there is more chance that the driver will lag with the phse of the strings physical vibration There have been some strategies like that in the patents and I have considered adding more metal in the high string side perhaps to increase power. The best I could think of is a bi-lateral driver running in stereo with a more treble bias for the high strings... As it is, you can adjust the circuits treble bias to get the strings moving more by lowering the output cap in the circuit. That schematic for the fetzer ruby suggests 220uF as does the "champ" but I use a 100uF for better high string and harmonic response... good thinking though... pete Link to comment Share on other sites More sharing options...
mrjstudios Posted June 21, 2007 Report Share Posted June 21, 2007 good morning I have not built the F/R...it was proposed by GalagaMike in the tutorial he started. I don't want to sound mean or disrespectful...and I've held my peace for now...but I do think he jumped the gun a little. He only seemed to get it to the preliminary stage that MRJ has done, hadn't ironed out the problems or fully installed it and never really got full sustain across all the strings as mine did. I added to the tutorial my fully working guitar soon after to show the rest of the work that needs to be done. I would much rather he had presented his progress to us on this thread before posting the tutorial so these things could be discussed... Very true. I didn't build off of that tutorial actually.... so don't be worried. I found the F/R being talked about HERE, and after some research, I really just went for ease of building, not performance. If you've got an about equally simple or simpler design that would really increase performance and not have as many problems as the F/R seems to have for everyone, then I'd be all for it. I just think that the L386 seems to be a really good contender for the poweramp stage.....but I'm not all for it if you've got better. While G'mike's work was ok, he did not follow my formula completely (slightly different wire guage, SS core material, wider core. neo-mags oddly placed, high cap in the output stage) and never adressed the problems he encountered (e.g...no harmonic drive). The F/R turned up completely unexpectedly in this tutorial and to this day I have never built it...so I can not check it either. It is however a valid solution for the project and not the source of the problems he encountered. Right. That's why I've tried to stick with the general formula and slowly add my own ideas (none of which have really helped any yet but haven't killed my project yet either.......yet) Also, that is why I really want a good "standard" working amp, so that I can get to the important stuff that I may actually be able to improve, which is the driver. The F/R is a mix of two circuits from RoG. They are minimalist to say the least. Ah yes, that is why I like it.... but not the Fetzer really, it was just a logical first step.... The data sheet for the LM386 for high gain (bridging pins 1 and 8) suggests the extra components that I and the ("champ" designer) included to avoid oscillations and such...LM386 Data sheet look at amplifier with gain of 200 circuit. I tweaked mine further to use a 100uF cap to bring out the highs more to get better high string response on my guitar. The fetzer preamp stage has had a lot of builds, but it is designed for "tone"...that is, it is supposed to overdrive a little...is that what we want here? Not at the cost of complicating things with difficult to find Jfets and trim pot biasing...grrr Ah, that is where the data sheet went.... wait, did you put the 100uf cap between pins 1 and 8 or in the output stage as a replacement for the original 220uf? Also, what should I put in between pins 1 and 8? That migh clean up sound a bit.... Basically...I have never had a problem with the LM386...that is not to say things haven't gone wrong from time to time...I put one in backwards once, used a socket and the thing was not damaged at all by having the power going backwards through it's inputs!!! And minimalist is fine...my first experiments used a LM386 with an output cap, no preamp at all and worked (really, two components everything else is in the chip)...but that won't work for the real thing (loading and such)... Now that's the kind of simplicity I like!! Now...I figure a matching IC based circuit just as easy to build and failsafe is the go...but I have an aversion to discrete transistors for some reason...they may "sound better" but that is not required here, otherwise we'd use tubes! A chip like the TL071 or 072 perhaps...is the obvious choice...widely available at least. Ok -- post a solid diagram and build it first, to make sure it works, and I will be the first to copy it and test it too! But...you want to look a little ahead...if the direction I am moving in is the future for this project...you may want the phase reversal built into the preamp stage...this won't become fully apparent till I do it I guess, but I believe there are significant benefits to dividing the two circuits (as col's effectively does BTW)...particularly with mid position drivers and small cavity guitars. I'd like to see a F/R circut modified visually like this, so I could understand this concept a little better.... then maybe I could try it as an F/R mod, (and by the way, maybe figure out a simple replacement for the Fetzer portion that sounds 'cleaner' and not 'better.' Plus, you can troubleshoot each circuit separately! Also, if I were to invest in making something available in some kind of kit form (as I'd like to do, and solve all of these probems) I'd want to be sure that the solution is right. While the circuits I use work for me, I don't think they are "right" or will suit everyone...nor are they the most compact (though not large) for this particular application. I would buy this.....$$$$$$$$ oh, sorry.... A$A$A$A$A$A$A$A$A$A$A$ yes...and yet... If you separate the power and preamp stages, you can easily swap them out...say build col's preamp, or a different poweramp. That is what I meant.... dump the Fetzer, but maybe keep the L386. -MRJ Link to comment Share on other sites More sharing options...
psw Posted June 21, 2007 Author Report Share Posted June 21, 2007 (edited) HaHa... Ok...well see what comes of this...I might be running into a little money to invest in something... Now...this stuff isn't really complicated...a circuit like this is pretty foolproof and would suffice to eliminate loading. It is a buffer (so has no gain) but very small and only cost a few bucks to build...dead easy even without a circuit board. This is the kind of thing I would be looking at...maybe a few more features. It might require a more powerful poweramp, maybe not... What I am considering is a little more complicated or refined for our purposes, but no harder to build than this kind of thing...I think this kind of circuit is much easier than the fetzer...but maybe that just me What I am trying to work towards is building the poweramp into the driver (hence power supply required to the driver as well as signal, so can run the LED's at the same time). Imagine a little circuit like this under the driver and this kind of thing (with phase reversal) in the control cavity...comapre that to the commercial sustainer and I think you can see that we are moving towards a vastly easier "product" to implement. A mid driver does not require any complicated bypass wiring and inevitable troubleshooting for each individual instrument. Now a little more progress... Still mucking around with my rewire...I did further developments but didn't like the changes made and tried to put it back but it doesnt quite sound as good as I remembered it...still some good sounds and quite a variety...but I am always seeking more... Actually...the sustainer project is getting me nervous as I really don't know if it will work in the mid position...so anything to put it off a little... Knowing that I put the shoulder to the wheel and got a bit more done...I have made a base plate and glued the driver to it and wired it in...so now I can show you the first fuzzy pics of the install... Here's the base plate details... And here it is fitted to the guitar... It all fits nice and neatly on this guitar...it sits up pretty high (there is plenty of room under for circuitry after testing for instance...and aesthetically it is nice and shiny, especially impressive for a first go. However, although it works as a driver, whether it fulfills the task of operating in this position is yet to be seen. As I am detirmined to make something work, all the work I have put into creating this one will not be wasted...I have developed some building techniques that will make repeating or altering it a lot easier and of course the guitar is now prepared for it. I have to say...this close driver in that position is going to take some getting used to...but it really will need to operate close to the strings. Here is a side view... I was also hoping that the effect of the action in this position will be significantly less for consistancy, but it appears not to be so much, so perhaps col's circuit which addresses this, will be of more benefit...I'll get around to that col! Otherwise...it does look kind of professional...it looks like it belongs on the guitar...a piece of hardware more than a picup perhaps in that design. Even the little LED is pleasing when on...just a mild glow from the sides. As impressive as the driver looks, a more conventional pickup look could be better, this one is a little longer than it need be and it may be possible to build a modified version that squeezes into a SC pickup cover for a more conventional look and professional "look"...I'm getting used to this one though... So far I have made no permanent modifications to the guitar...not even had to drill a hole in it or anything. While planning to fit mini toggles on there and it would suit the guitar...it is kind of tempting to try out some kind of add on control...not so much a "box" as we had envisaged before, but something that sits below the bridge or something to activate it...something like tis would make the whole project reversable and potentially transferable to another similar instument. I'd stll like to see a momentary activation switch for this device...it may well happen if things continue to go well with this. People like Tim (onelastgoodbye) and others who have followed the thread for a long time will be able to spot how much of the early vision is coming into being at this stage. Multiple pickup use, low modification, compact drivers, even the LED thing and perhaps the momentary control...are actually coming into being, kind of heartwarming Let's hope it works and we can get on with refining the device and it's circuitry and installation. I certainly have given it every chance of working...so it had better, cause I'm running out of ideas (never)... Going through some stuff I have found several built and unbuilt kits of the circuit I have been using. I have yet to decide whether to take the signal directly from the humbucker or to take it after the selector so the signal changes with selection. I may well test it with my tried and true circuitry...or, I could do some work on developing something new. I have the components for the poweramp and for a few simple IC circuits and design ideas, but I shouldn't really bog the project down with untried or underdeveloped ideas...too many things and even if it does work, we will not be able to tell why and how much of the design is superfluous (the side fin shielding for instance)... I have already begun some further research into alternative circuitry (again) and will move in this direction even if it does work with the circuitry I have typically used anyway as a "standard" basic circuit is pretty important to replicating the thing...especially since people interested in this have little electronics experience at all. Eventually of course, as we have discussed, we could come up with a design and method...and perhaps even material supply...that is standardised, foolproofish and more approachable for the average peerson with a soldering iron and a multimeter and a knack with arts and craft like aspects of the project. one last pic to leave you with to keep you enthused...comments, suggestions and encouragement welcome... pete PS...I found this layout for the fetzer ruby from bianka (where is he, he was making this project at one stage) from his fantastic and free DIY Layout creator... Edited June 21, 2007 by psw Link to comment Share on other sites More sharing options...
mrjstudios Posted June 21, 2007 Report Share Posted June 21, 2007 PSW So that IC buffer would replace the Fetzer? In other words, we could build a RUBY amp and run this IC buffer into it for the same/better effect that the Fetzer has? Cool. That is simple.....I like things that are that simple in the DIY circut field.... I may build a ruby with champ mods, and then create a simple plug-in system between driver, poweramp, and preamp, using plastic computer type plugs so that I can easily switch parts in and out without soldering. I must say I had my doubts about the appearance of a "giant" aluminum bar between your 2 blade cores on your driver, but the finished product looks great! It really fits in with the guitar. Even the LED's look cool..... (wow, I can't believe I think that ) The only thing that would make it look more uniform with your guitar (but not necessarily better) would be to paint the mounting plate black so it looks like the other pickups. I myself would leave it silver, but those of you going for the "hidden driver / uniform look" might want to consider that. Either way, it looks great. I hope you can do an audio or Youtube test later so I can hear it! That F/R is basically the layout I use. Except that jumper between C2 and the ground that runs 'under' R1 looks different. I'll check my circut and see if mine has that.... -MRJ Link to comment Share on other sites More sharing options...
psw Posted June 21, 2007 Author Report Share Posted June 21, 2007 Thanks...yes it does look cool...hope it works! I'll see if I can whip up some kind of tester circuit today perhaps... Meanwhile...that circuit is only a buffer, we may need a little or a lot of gain in the preamp to help it along a little. This circuit is again the bare minimum...I would add a cap (100uF) between the +ve and ground to smooth power and a circuit protection diode (to prevent damaging the circuit should the battery be put in backwards), perhaps a pull down resistor to run an LED from (mine is built into the driver) and maybe a resistor between the input and ground to help prevent switch noise and pop. To turn a buffer like this into a gain preamp requires 2 more resistors, one could be a trim pot for variable gain. A circuit like this...Guitar Handbook Preamp...shows the same kind of thing as a gain stage preamp that really would replace the fetzer (but of course takes up more space)... I really think that the op-amp building block type of design suits the kind of people who want to build this kind of thing over the space saving features of a circuit like the fetzer...but, as I say, that might just be me. For my purposes, I really need to have the phase reverse harmonic function in the preamp stage, not on the power amp leads as we have been doing...there is too much risk of EMI from these wires trailing around the control with the present scheme. This kind of design work is not my forte so if anyone has any ideas...meanwhile, such circuits are not expensive to try out and test, so once we have the device working in the mid position I will move on to this design ideas before fully installing the circuitry and any switches required to run it. pete Link to comment Share on other sites More sharing options...
mrjstudios Posted June 22, 2007 Report Share Posted June 22, 2007 I'll see if I can whip up some kind of tester circuit today perhaps... Sounds good. As long as you can keep me up to speed with the entirety of the circut you are building/designing (in other words, show me a layout or diagram for everything inbetween the battery and the driver itself -- the WHOLE circut) I will continue to build test circuts as well so I can get past the circut problems and try to help improve the mid driver design. I wouldn't be as eager to do this with my poor soldering skills... but with even my 2nd F/R acting up, and my soldering quickly improving, I need something better. -MRJ Link to comment Share on other sites More sharing options...
psw Posted June 22, 2007 Author Report Share Posted June 22, 2007 200 pges... So...didn't get time to test it yesterday, but perhaps today! I will be testing it with my usual circuit and even found an amp and preamp already built, so well on the way there... As for a new circuit design...that is another problem. This has been going on for a long time and I have put in considerable effort without success in the past to do this. People should note that I pretty much taught myself electronics to do this project but there are a lot of deficiencies in my skill set in this area. Still, we are talking some pretty basic stuff, so I will have another go (I don't like to be defeated). Col's circuit is more ambitious than what I could design so people should seriously consider this approach. I have been doing a bit of research and we will see if it comes to anything. I am thinking a dual opamp circuit with two inverting buffers/gain stages...one for normal mode and the other to flip the signal back over for harmonic mode. Such a strategy may have other benefits such as simplifying switching (smaller SPDT switches) and may even allow for the operation of the device with a single on-off-on DPDT switch...we'll see! If my proposed new poweramp (lm386 replacement) works out ok, this preamp may only need to buffer the signal to prevent loading so wont require anything too complicated. The poweramp section has even less components than the LM386 version and is smaller, though a little more expensive and harder to get. If this kind of thing is the best way to go and will serve conventional and mid-drivers and saves on switching (an expensive part of the project) and provides more options...this is probably the way to go...especially if I am considering supplying parts or making a circuit board up for it. First things first though...this project strives to keep the circuitry mojo down and concentrate on driver design, no circuit will compensate for an inefficient driver! I will test it with the present known circuitry before embarking on deign issues, swapping out the poweramp, then the preamp till I get the right mix. There is always the chance of course that this driver fails to function in this position (I have tested it in the usual way with success of course)...then I will have to rethink the design and specifications till I develop something that does work...better get to it... pete BTW...if 200 pages here are not enough, or too much...there are some occasional threads here (guitar nuts forum) and here (DIY stompbox forum) Link to comment Share on other sites More sharing options...
psw Posted June 22, 2007 Author Report Share Posted June 22, 2007 (edited) EEEEK...preliminary tests are not going well...severe EMI and "motorboating"...will have to test the amp circuit and tidy up connection to the guitar to reduce cable length. It could be that the driver wires running right alongside the pickup wires (even though in shielded cable (which wont protect them from EMI really...more for RF protection) is making the problem worse...hence my desire to have the power amplification with the driver... More likely the driver design is just not good enough for this application and we will have to do some further development...arghhh!!!! A bit early yet to be sure, but it probably was a bit much to expect the first try to succeed no matter how well built it is...will update when I have some more conclusive results... Any thoughts or encouragement appreciated...the benefits of an eventual working mid-driver are too great to let go at this point...it could be a few weeks before I could redo another driver...my window of opportunity to play with this, this much is closing... pete Oh...and yesterday I spent most of the day going through boxes and sorting through stuff post the move...all this electronics stuff was just thrown quickly into boxes (literally) and what I am supposed to be doing is sorting through and throwing out stuff (not building more!)...but I found lots of interesting stuff. A roll of 0.125 wire (too thin?) and plenty of magnets and tools...a huge collection of failed drivers (mostly from the hex era of the thread)...and a lot of components and stuff. I even found an opamp preamp kit (if only I can find the instructions) that could fit the bill instead of the fetzer) and a TDA7052 based BTL amp that could fit the bill to replace the LM386. A little research shows this amp is available in stereo...perhaps we could independantly run two 8 ohm coils rather than 16's in parallel, or power a bi-lateral driver with separate signals. Speaking of which...none of us have ried the bi-lateral approach yet, even though this is the design that Sustainaic uses and dizzy successfully used in his mid-driver strat (see the sustainer sounds diablo mp3, very convincing)... Still...haven't completely given up on this one yet...it is showing symptoms distressingly similar to the problems I encountered with some of the Hex drivers...just too close to those pickups...grrrr Edited June 23, 2007 by psw Link to comment Share on other sites More sharing options...
psw Posted June 23, 2007 Author Report Share Posted June 23, 2007 EEEEK...preliminary tests are not going well... well...that's a bit disappointing...but lets move on for now... Since I have the bits and it is on my mind...and it might help...I did a layout and built my new proposed amp to fit under or into the driver... These photos are bigger than actual size...see the pick for reference...very tiny, very few components and a very simple board...(the down side is the chip is a little expensive and hard to locate...but I think I got a handle on that for the future if it proves successful ) The chip is supposed to put out a whole watt of power (more than the LM386) and uses the BTL principle so the driver is not connected to the ground (which may also help). If it does put out sufficient power, it may be that the preamp need only be a buffer making that easier to design and with less components (cheaper and smaller). I hope that seeing this will give you some idea of the kind of direction I am working in and how the circuit could perhaps be simplified and made very small. Lets hope the EMI from the driver doesn't interfere with this amp module under it... I even included a volume trimmer but that may not be necessary and impossible to adjust where I want to stick it anyway...omitting it would have made it even smaller...(as would leaving out the chip holder...used for recycling purposes). I have not included details of this circuit as yet because we really don't know it's value to the project...even a LM386 version would not be so large and fulfill the same role. As long as you can keep me up to speed with the entirety of the circut you are building/designing (in other words, show me a layout or diagram for everything inbetween the battery and the driver itself -- the WHOLE circut) yes...so don't run out and buy this chip as yet or try to replicate the circuit...there still needs to be more done and it will need a matching preamp to get the thing running as a system... Now...I say it might help as putting this part of the circuit nearest to the driver eliminates high current leads running through the guitar that can cause trouble. I already have the driver wired for power (remember the LED's) and although it should have a smoothing power conditioning 100uF cap in it...I will locate that with the preamp since that will need it too. If it should be that this driver does fail in it's mission to work in the mid position...if I have the circuit built in, I can snap off the exisiting driver (it is super glued on) and try different designs on the same base plate...I haven't given up on it yet though...both avalon and juan seem to suggest that their similar drivers would work in the mid position, so it may not be my driver so much at fault. wish me luck... pete Link to comment Share on other sites More sharing options...
psw Posted June 23, 2007 Author Report Share Posted June 23, 2007 Hey...well that was so much fun, I built a matching buffer using the Orman schematic posted earlier and a few mods... Hope your soldering is as neat as mine.... Anyway...very cute! This buffer has no gain but will prevent loading of the pickups and provide the power conditioning and protection for the little amp. While it probably wont serve as a preamp for the sustainer ultimately (no phase reversal, etc) it will aid in testing and by itself will make a guitar effectively "active"...so I'm sure I will find a use for it somewhere. It is a great starting point...ultra-simple and compact...plus I had the parts...so no cost... Anyway...might not get a chance to do much more in the way of testing today (and possibly a few days from now) but will try to connect this duo to a speaker and get an idea of the sound and output...then well have another go at this mid driver! Already I am schemeing new designs but I am a little confounded as to why this one hasn't been more promising...perhaps there is something wrong in the circuitry or EMI within the guitar...hmmm pete Link to comment Share on other sites More sharing options...
psw Posted June 23, 2007 Author Report Share Posted June 23, 2007 (edited) Hmmm...well some good news... The mid-position driver is working...with some provisions... I re-tested the lm386 based circuit and (connected with crocodile clips at both ends and all kinds of noise inducing connections) split between the output of the actual guitar (not a direct feed from the pickups before the controls)...and I am getting infinite sustain on the lower strings. Unfortunately there is a fair amont of fizz and distortion...not good. However, turning it down and playing with the gain between pins 1+8 and out of the preamp, I have been able to get some reasonable sounds out of it. Raising the bridge pickup and adjusting the driver also helped quite a bit. On a very low power the low e gives mild infinite sustain without distortion...it's all a matter of balance I think...a clean signal would also help I'd assume (it wasn't too pretty through the speaker!) Now...this guitar still has very light strings on it so getiing the high b and e going was going to be a bit of an ask (though the b sustained quite well in testing over the neck (edit...ooops, that was with the other guitar and it's internal circuitry)). Adjustment of the appropriate amount of power seems to be pretty crucial then...perhaps col's more controlled circuitry would be of benefit. I also just checked and the amp has the original 220uF output cap...not the 100uF that I used to get better high string response, so that will be a factor too! Perhaps the preamp has not been modified, or the modifications that add enormous amounts of preamplification is way too much and causing excessive distortion. Up sides of this is that I have got some positive response, so we know that the driver can work in this position...it just cant have too much distorted power going to it...a question of efficiency. It also indicates that putting power through my driver wiring may not be too detrimental, so testing can continue without the "powered driver" scenario. Testing with a direct hard wired circuit will probably improve things a bit...modifying the amp or building another, may help some more also. As for my baby amps...they still need some debugging I think...the circuits seem fine but not getting a response from the speaker as expected. I am also getting an 8 ohm reading across the battery terminals connected to the preamp...that doesn't seem right! The TL071 is fragile and if connected wrong will fry (hence my desire for voltage protection to be added to the circuit. I don't think I fried it with this as it was checked several times before adding power but I did salvage the part from a circuit I had worked on a few years back and maybe it was fryed then...will take a little more experimentation on both these things...fun to make though, only took a few minutes. So...probably not a lot more I can do on this for a while...back to work and then the kids are over all week...and then back to work...then school holidays are coming...so there may be quite a bit of delay before I can actually do much with this, but at least we have some positives out of it and the driver still has a lot of potential afterall. Plenty of time to discuss things so feel free to make suggestions or comments... pete edit...found the problem with the mini buffer/amp...one jumper left out, it was supposed to be hidden under one of the caps on there...easy to do when things are so small. So...the two things work and work with eachother (the preamp powers the poweramp)...however the response is a little disapointing...seems to go into a tremolo and the chip gets quite hot...perhaps it is not as loud as advertised and has auto shut off so maybe it is trying to protect itself...hmmm. Heat isn't a problem as I could glue the chip to the aluminium driver base plate to keep it cool (always thinking) but I think the LM386 give out as much power. The LM386 "champ" circuit can be made pretty small...as gain adjustment may be critical, I will try and arrange a compact layout so as the trimmer could be adjusted through a hole in the triagular part of the base plate...ok for this guitar, but not really ideal for a universal device...any thoughts? p Edited June 23, 2007 by psw Link to comment Share on other sites More sharing options...
mrjstudios Posted June 25, 2007 Report Share Posted June 25, 2007 Ok, just got on and read all of your updates PSW.... last few days this website said it had exceded bandwidth and was shut down.... I really like how those circuts are looking. Very, very simple (most important) but very small too. Hearing about the response problems, and the lack of a power advantage with the new chip, again I am leaning towards the LM386 because it seems to do much better with high-end response when fitted with the right caps (like your mods and the champ circut) and it doesn't run hot. Even running my 9v (which was really like 10v) straight thru one of my first simple circuts and into the LM386 for over half an hour, it did not overheat, or even get warm enough to worry me. Just something to consider..... Another thing is that whenever we do get a better circut here, I may put the power amp section up near the driver, but I will still stick the first stage back in the guitar cavity that I made for the sustainer, (with the battery), and put the controls near the output jack and other guitar controls like they are currently. I may get a little more EMI than you guys, but I'm not using a full mid-driver either.... Anyway, the one thing that I like of your circut as-is already is the buffer that would essentially replace the Fetzer. That is perfectly simple, and it looks like it is a solid design, with only necessary parts. One question: Is it possible to build the poweramp stage that you built with a LM386 substituted in? That other chip is the same form factor, and the circut opperates in about the same ranges (i would think), so could the design be either unchanged, and a 386 swapped in, or slightly modified to put in the 386? Remember also, the Ruby was built for "many shades of sparkly clean all the way up to a great, natural overdrive." And I think I have been getting into that 'great, natuaral overdrive' which is bad for a sustainer. With your circut that replaces the Ruby, no J201's are used, which makes the circut much simpler, and cleaner sounding. I think the J201 type chips are basically meant for distortion, because I am building a DIY stompbox that simulates a Marshall 100w Lead Stack, and the SOLE chip in it is 4 J201s! Finding that out really made me take a closer look at my sustainer circut, and want to get rid of the J201 (like you did) so that I could get a cleaner sound. -MRJ Link to comment Share on other sites More sharing options...
psw Posted June 25, 2007 Author Report Share Posted June 25, 2007 Yes...well we were down for a little while, but back now... Hearing about the response problems, and the lack of a power advantage with the new chip, again I am leaning towards the LM386...Just something to consider..... Oh...I haven't ruled it out! The LM386 is pretty indestructable and easy to find and use, but it is also pretty old. I planning a compact stripboard layout of my "champ" circuit which too will easily fit where I am planning and serve the same function (quite how I will adjust it's gain I'm not sure)... Another thing is that whenever we do get a better circut here, I may put the power amp section up near the driver, but I will still stick the first stage back in the guitar cavity that I made for the sustainer, (with the battery), and put the controls near the output jack and other guitar controls like they are currently. There is no problem with that, but I do think building the two parts separately may make things a little easier and flexible no matter how it is to be arranged. My sustainer strat has a cavity directly behind the output jack with the battery and all circuitry in there...the driver wires run through the trem cavity to cut back on potential EMI problems. Most if not all of my present difficulties are from the mid-driver application, I am sure it would as well or better in the neck slot as my SC design. Anyway, the one thing that I like of your circut as-is already is the buffer that would essentially replace the Fetzer. That is perfectly simple, and it looks like it is a solid design, with only necessary parts. Well, the buffer is a first step for me to get a better feel for what is required. I will test this with a modified LM386 circuit and see if that works...I suspect though that the preamplifier stage needs some gain, so my next circuit will be a simple gain stage along the same lines that really could replace the fetzer. That, at least will give us a basic easy circuit to work from as an alternative to the F/R and designed specifically for this application in mind... Is it possible to build the poweramp stage that you built with a LM386 substituted in? That other chip is the same form factor, and the circut opperates in about the same ranges (i would think), so could the design be either unchanged, and a 386 swapped in, or slightly modified to put in the 386? No...the TDA7052 is quite a different animal. It works on a BTL principle and has no output caps and very little extra components...it can't be swaped over even though it is the same 8 pin dip format. The champ circuit needs at least 3 (possibly 4) electrolytic caps that take up the bulk of the space. Still...it is a pretty small and certainly easy and well tested circuit. The next layout will be an LM386 based design. Even though, running flat out the LM386 is certainly not clean...for that you will need a lot more headroom and power than we could supply. Remember also, the Ruby was built for "many shades of sparkly clean all the way up to a great, natural overdrive." And I think I have been getting into that 'great, natuaral overdrive' which is bad for a sustainer. True...so there is no point designing distortion into the circuit and messing with these tricky J201's that people seem to have trouble finding anyway (I can't get them for instance!)... With your circut that replaces the Ruby, no J201's are used, which makes the circut much simpler, and cleaner sounding. Well...the buffer doesn't strictly replace the fetzer quite yet...maybe a little gain is required. In my previous preamp, there is a lot of gain, far more than the fetzer. It is inevitable that as you raise the gain, you will distort the input of the LM386...and if you run the LM386 at 200x amplification, it will circtainly be "distorted"...the point is that you shouldn't hear this distortion, it shouldn't get into the signal chain....that is where the EMI control comes in, and driver efficiency! This buffer circuit is a good place to start for me though...it is only a matter of adding a few more resistors to adjust an opamp for unlimited gain! It may benefit from some filtering of very high frequencies to reduce noise as well and prevent internal oscillation. It is a matter of taking it step by step for me on this...I do get ambitious and then find that the things fail...having made this one, I can swap out that chip into another layout using chip sockets and save on parts too, so there really isn't any loss (except in hair!)... Finding that out really made me take a closer look at my sustainer circut, and want to get rid of the J201 (like you did) so that I could get a cleaner sound. Well...it should be a little cleaner and there are lots of opamps with the same pin outs that could be substituted with different "sounds" or qualities (cleaner, lower power, etc)... The main attraction is the availability of parts and the lego like simplicity of putting together a circuit with IC components over discrete parts like the J201 (plus the biasing etc required) that makes things difficult for beginners to be assured of success, at least with the circuit. This project is demanding enough without having to worry whether even the circuit is working as it should! Anyway...one thing at a time...this mid-driver is going to take more than a fancy circuit to make it work as it should... pete Link to comment Share on other sites More sharing options...
Avalon Posted June 25, 2007 Report Share Posted June 25, 2007 Hiya everyone, sorry i've not been about, not getting anything done atm, its one of those months, but i've been reading everything thats going on and great to see it still progressing nicely, great stuff When i get a minute im going to skip straight to Cols circuit and test it on my installed driver to see how that works, i'll let you know how that go's as and when it happens. Also Happy 200 pages, its testiment to an excellent thread, project and developers, everyone who's taken part give yourself a good pat on the back, some amazing work has been done here Link to comment Share on other sites More sharing options...
mrjstudios Posted June 26, 2007 Report Share Posted June 26, 2007 The next layout will be an LM386 based design. Good. I got 2 here, so I can help build your test circut whenever you post the layout very fast, and without having to order a lot of parts. I'm glad we are addressing the circut now -- because I can't even begin to test and re-design my dual coil driver without a good circut! I am basically stalled..... So any developments on a new (especially a LM386 based) circut is appreciated! -MRJ Hey, wait a sec.... could a dual Ruby or dual champ amp be used as a preamp/poweramp setup?...... Link to comment Share on other sites More sharing options...
mrjstudios Posted June 26, 2007 Report Share Posted June 26, 2007 Another thought..... This is a 4 watt 8ohm practice amp that runs on 2 x 9volts or a 9v adapter (it should run on just 1 x 9volt). Although it is 4 watts, couldn't this run a sustainer if turned down very quiet, or if some sort of resistor is added in before the output? It is a little big (10cm x 7cm), but could be put in a guitar, or run in a "driver box" like you had before PSW. Since it is a guitar amp, it should be premade for the right frequency ranges, and it already has all of the necessary inputs and outputs that a sustainer related amp needs (+ an added bonus of a 9v adapter plug built right in it!) I want to use this to test my new drivers until we get a good solid custom circut devised here, so I don't fall too far behind with the dual coil project.... Tell me what you all think.... -MRJ Link to comment Share on other sites More sharing options...
psw Posted June 26, 2007 Author Report Share Posted June 26, 2007 I want to use this to test my new drivers until we get a good solid custom circut devised here, so I don't fall too far behind with the dual coil project.... There wont be any harm in using this to test the driver at low volumes...however it would be impractical in a guitar. BTW, it probably needs the two batteries to achieve it's +/- powersupply so don't try modifying it for one! Hey, wait a sec.... could a dual Ruby or dual champ amp be used as a preamp/poweramp setup?...... Funny...I had the same thought yesterday that I could use a dual lm386 to increase the power and headroom to get a cleaner signal...hmmm It won't work to replace the fetzer however...the preamp stage is necessary to avoid loading the pickups and to provide the initial boost to condition the signal for the LM386 chip. Nevertheless, opamp preamps really are 101 in electronics and it is only because I have not got a formal education in the field (I just pick up what I need to know for this stuff) and I haven't been playing with this stuff for a while, that I just don't whip one up like I did that little preamp the other day...still working on it! I may get time to do a bit of a tinker today...I won't post things that I haven't built (been burnt before) and even then it is tricky with this mid-driver because the problems are more with the location of the device, not the circuitry as such. I could be that it would benefit from more power so that it could run cleaner...but every time I think of col and his desire for less power consumption...much more and it would not be ptactical to run this from a battery at all!!! SO...I think I have a stripboard layout and parts for the LM386 circuit that I have running in my suatainer strat and I do have preamp designs to play with (though I may need to get some more parts)... However, the children are over this week and there are plenty of things that I should be doing...today is wednesday so is normal people's sunday...wash day! pete Link to comment Share on other sites More sharing options...
mrjstudios Posted June 26, 2007 Report Share Posted June 26, 2007 (edited) Well, I'll just use that mini amp for my tests then.... at least for now. Go #2 at the 2 x 16ohm parallel driver is underway. I just stripped the coils off of my first one and re-wound them...they are drying now and this time one is 15.9ohms and the other is 16.4ohms!!!!!!!! The other one just wasn't gonna work so I deceided to scrap its coils. This one will look better too -- more like PSW's, but with a white finish instead.... I have a putty made by Testors that is kind of like epoxy putty -- I think, so I may use it instead of so much hot glue. As for the magnet/core spacing, do the cores need to directly touch the magnet, or can the magnet be spaced in between the cores with hot glue or other non-magnetic substances about 3mm away from either core and still be effective? -MRJ ***EDIT/UPDATE*** Progress report: The 2 cores are now re-wound and potted. I used a similar technique as PSW this time, as an add-on to my temporary bobbin construction, by squeezing the coil in towards the center along its length right after winding it and checking its ohmage. I did this by clamping scrap pieces of plastic inbetween the bobbins (cut to 3mm like the height of the coil itself) using slight pressure from C clamps. This method very effectively and evenly squeezes the coils inward without risking wire cutting or mishaping of the coil. (I will post pictures later -- it is too late and dark now.) I'm letting it dry over night for "coil shape retension" safety and then will take off the temp bobbins in the morning and further squeeze the coils in when I slide the cores onto the permanent bobbins (like I did with the first one). These slight changes in my design will make the coil spacing more similar to PSW's, but not quite as compact. For some reason I think there is some sort of advantage in keeping it a little further apart, but I could be wrong. I will then use the above (pictured) amp to test the new driver when it is done. (I would say in 1-2 days...) And most importantly -- YOUTUBE video(s) will be posted so that everyone can see a realistic demonstration of our current progress. (If it is possible for you PSW, please post at least some sound samples!!! I would love to hear your sustainer and your playing!) Also, once we get the circut figured out, and regardless of the dual coil project's progress as a whole, I think me, PSW, Avalon, Col, and any other of the "big experimenters" should make some sort of "finalized" tutorial and perhaps a website devoted to the circut, the single coil driver, the dual coil driver, and tapping into your guitars wiring to modify it for the sustainer. That way, we could still use this forum to discuss progress, but beginners like me (a short time ago..) could find solid designs and a much more approachable source of info. -MRJ Edited June 27, 2007 by mrjstudios Link to comment Share on other sites More sharing options...
psw Posted June 27, 2007 Author Report Share Posted June 27, 2007 (edited) As for the magnet/core spacing, do the cores need to directly touch the magnet Yes they do...near enough is not near enough I am afraid. One of the reasons I had to squeeze my coils (similar to your method BTW and that of Tim's jigamethingy) was so that the magnets would make contact with the cores...you could fill the space with metal pieces perhaps...better to touch though! Also, once we get the circut figured out, and regardless of the dual coil project's progress as a whole, I think me, PSW, Avalon, Col, and any other of the "big experimenters" should make some sort of "finalized" tutorial and perhaps a website devoted to the circut, the single coil driver, the dual coil driver, and tapping into your guitars wiring to modify it for the sustainer. That way, we could still use this forum to discuss progress, but beginners like me (a short time ago..) could find solid designs and a much more approachable source of info. Yes...we have discussed such things but we really need to have the project solididly beded down I feel... I have done a little research and tinkering today (between washing, etc)... I have found a buffer circuit with polarity reverse function...but there are other options too...this is intended to provide the harmonic function and so allow more flexability with the location of the driver and switching of this thing. I have also found some ideas for using two LM386's in bridge tied load (BLT) mode...this uses two lm386 chips, one amp each for positive and negatice cycles of the signal. I have no idea how much poser this would consume but I am hoping that perhaps if pin's 1 and 8 are left open the combined output will be less than the single LM386 but considerably cleaner...we will see. I also worked out a really cute layout and miniture circuit for it and built it up. It has no output cap/s so actually is simpler and less parts than the "champ" type amp I have been using, but I have carried over some of those design features as well. If this kind of approach works out, perhaps a simple buffer will be all that is required. I have played with the mid-driver a little more...on very low amplification you do get infinite sustain on the low e and a strings without much if any distortion...to get more response though you end up with a lot of EMI "fizz" and distortion. I don't get the squeel like feedback even at high gain but there are background oscillation noises that are unacceptable. This mid-driver design does work then, but it may need a very clean signal to really be effective I suspect. There are plenty of things yet to play with in the circuitry, but I don't know if that will really be enough. I intend to go as far as I can in this direction then, if necessary...try a different driver design (perhaps a bi-lateral approach), or the same design with different specs. I'd be interested to know what col thought of these directions and if his preamp design would be applicable to my mid-driver endeavours... pete UPDATE: I got the dual BTL lm386 hooked up with the buffer and a speaker and it does work...still fairly distorted (crappy little computer speaker)...I could bridge picns 1+8 for a 400x boost, but that would be way too much and kill the battery anyway...hmmm Perahps a little preamp gain is in order, will try that if I get a chance but may be a little while before I can do anymore work on this for a bit! p Edited June 27, 2007 by psw Link to comment Share on other sites More sharing options...
mrjstudios Posted June 27, 2007 Report Share Posted June 27, 2007 (edited) Well, another test on the driver says that it will be approx. 7.3ohms when finished.... Should be ok.... It is drying right now on the permanent bobbins. I really was able to squeeze it together, so that there will only be a 1mm gap on either side of the magnet between the cores. That can easily be spaced with steel as opposed to the 3+mm gap on the 1st try..... I think I will use that Testors "Contour Putty" to fill and solidify this driver. Hot glue will only be used to tack the magnet onto the bottom of the bobbin. Also.... I found this a ways back in the thread. It seems to explain in detail the circut and other "trade secrets"......just scroll down. http://www.freepatentsonline.com/5932827.html -MRJ Edited June 27, 2007 by mrjstudios Link to comment Share on other sites More sharing options...
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