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Post by ozboomer on Nov 25, 2009 3:42:33 GMT -5
Just a quick posting to update the layout, including the Treble Bleed treatment for the blender: As a reminder, the modifications shown in this layout are: - Mod 1: Main Output Treble Bleed
- Mod 2: Volume & Tone Control (possibly changing with preamp, etc)
- Mod 3: N+B Special Switching via 3-way switch
- Mod 4: Parallel/Series Switching
- Mod 5: Series Blender
- Mod 6: Treble Bleed for Series Blender
Back to the on-going studies/scoping of preamps for possible inclusion in the design... John
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Post by ozboomer on Nov 26, 2009 20:50:10 GMT -5
I've been thinking about this idea of working on a preamp module for this design... but given my situation, I'm not really sure how helpful that would be. No doubt, including the preamp would definitely help with ensuring I have a good signal level into an amp or into a mixer for live playing or recording. However, I'm having reservations about the concept of using the preamp module as something to provide a mild overdrive sound. At home, where I generally play, I am using a solid state amp (Fender Frontman 15R) and otherwise, I'm plugging my guitars into a BOSS BX-600 mixer (old!) and/or directly into a PC for recording using a Behringer UCA202 audio interface. Thus, I'm hardly ever plugging into a tube amp, hence the 'overdriving' feature provided by the preamp will be used very rarely. So, I'm thinking there's not going to be much point to the preamp, as I generally don't have troubles with signal level into the mixer or into the amp. If I did go ahead with including the preamp, I'd also probably have to do something to give me some control over the preamp. I guess that would come from 'tuning' the range/effectiveness of the overdrive function. In its simplest form and given the arrangement I want to use with the pots, etc in the current design, I'd probably have to define some points in the volume control travel where the overdrive would come in. Doing so would re-introduce the problems from the original SPlender design, where controls have more than one function... and I don't want to get back that complexity again. Hmm... It would seem I should be thinking about a stomp box or something similar. I already have a lot of those effects available via my V- Amp 2... so I don't know how helpful the extra stomp box would be. Anyone have any further thoughts? Thanks. John
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Post by ozboomer on Nov 30, 2009 20:32:24 GMT -5
"We have the technology..." I've been continuing my tone control experiments and very quickly I found that working with a couple of resistors and capacitors was probably too hit-or-miss, given my ordinary ears... Therefore, I went the VST route. I already had a stack of filter VSTs in my collection, which were all fine and good but they had too many features; all I was looking for was something that would give me similar behaviour to a "low pass filter" (LPF) attached to a "high pass filter" (HPF), 'coz I thought I could build a simple version of them with a couple of (variable) resistors and capacitors; I have to fit this mechanism in the guitar cavity space, after all.. To that end, I ended-up using GBand for my experiments. This VST allowed me to modify the (cutoff) frequencies for both the LPF and HPF and that was sufficient to give me some useful and interesting tones. Note that although this VST has a Resonance control, I wasn't really interested in using that. I'm still trying to go for some semblance of simplicity... and I don't want to add yet another pot, especially when the sounds it adds are not really what I expect/want to be coming out of my guitar; I already have synthesizers for filter sweep and vocal/nasal -style sounds. Anyway, after all this, I worked out that I like the LPF to track from 80Hz - 700Hz... and the HPF to vary 1000Hz - 15000Hz. Now, I'm not too flash with my electronics theory... but I've hobbled together some sort of starting circuit, viz: I understand the cutoff frequencies for each section of this circuit would come from some application of (1 / 2 * pi * R * C)... but how can I provide and calculate a range of frequency values? The circuit I've drawn is kindof ordinary, I know... Hmm... I guess I'm wondering if I can actually achieve these range of frequencies with a simple passive circuit design... or am I being too ambitious (again)? I'd appreciate any thoughts... John
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Post by sumgai on Dec 1, 2009 3:49:25 GMT -5
boom-boom, What I wanna know is, why'd you hook a capacitor in series with the "high" side of your volume control? And why did you keep the ground side from going directly to ground - you've forced it to remain 5KΩ above ground, which means that the output won't ever be completely damped down to nothing. (IOW, 0 on the knob won't shut 'er all the way down.) Oh, wait..... I see, there's some colored writing on the diagram.... it looks like a mis-label, something about a "High Pass Filter". Nope, that won't do. Ain't gonna be no high-passin' goin' on here, only a major reduction in overall volume, down to about the equivalent of "2" on most other volume knobs. Hint: try this for starters: Nutty Discussion on Tone controlsAt the top of page 2 of that thread, you'll find: JohnH's GuitarFreak Post, complete with a link to his interactive spreadsheet for Tone Controls, and another link for an explanation of what you're seeing. All highly suggested reading. (We've done lots of other things with this idea, but sadly, they are now lost to the Search function provided by ProBoards. I hate to "over-populate" the NutzHouse by repeatedly posting my own stuff, and what I put up way-back-when really was just a simplified version of what John's done more recently, so let's hope that he's got the goods that you want/need! ;D) HTH sumgai
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Post by ozboomer on Dec 1, 2009 4:58:45 GMT -5
My dear Mr Gai... What I wanna know is, why'd you hook a capacitor in series with the "high" side of your volume control? Volume? Wot volume? As I said, my theory is pretty *ick* in some things... and I *thought* I knew a resistor across a grounded cap = LPF... and swap 'em for a HPF... and, thinking mod-u-lar-ly, I just tacked 'em together... rather inappropriately (*P'thooey!*) it would seem... Oh Fanx! I tried to find that, as well as JohnH's calculator before I started all this but Search wasn't on my side at the time; many thanks again for coming to the rescue... ...and ya, I did scramble around a few of the discussions about filters and such in here... but, as usual, all that reading got me more confused than enlightened. Anyway, I'll have another look at the above references... and see if I can't clear the major pea-souper (of a fog) in my current understanding. John
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Post by sumgai on Dec 1, 2009 13:38:05 GMT -5
oz, No problem, it's a common mistake. And again, there're only 3 or 4 people on here that have a true understanding of Electrical (and Electronic) Theory - we're the so-called Engineers. The rest of the NutzHouse is getting along just fine without all the expensive edjumacation, TYVM. ;D To ease the pain a little, I like to quote myself (it tends to add spice to my conversations!): When I was a teacher at a local college (no, I never made tenure, so don't call me Professor, please), I told beginning students right off the bat that I wasn't smart about these things, that I wasn't born knowing all this stuff, that in fact there was only one difference between them and me - I was curious about this stuff sooner than they were. And now it was their turn to be curious, and to have that particular itch scratched. And so it goes in the NutzHouse - I'm merely passing on what I had to learn the hard way, from someone else. Call it payback, or call it 'paying it forward', it doesn't matter, so long as the string gets plucked, eh? </sermon> sumgai
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Post by sumgai on Dec 1, 2009 13:53:24 GMT -5
ozzy, As I said, my theory is pretty *ick* in some things... and I *thought* I knew a resistor across a grounded cap = LPF... and swap 'em for a HPF... and, thinking mod-u-lar-ly, I just tacked 'em together... rather inappropriately (*P'thooey!*) it would seem... Well, actually you were close, at least about the swap part. But look below, and see that if you don't ground one side of the variable resistor, then you're home free! Mull that over, and see if you can make it work in your mind, then go try it on the test bench. None of the parts values are not cast in stone, experiment to find the value that best suits your taste(s). HTH sumgai
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Post by ozboomer on Dec 1, 2009 23:04:48 GMT -5
sumgai, I've had a quick look at your layout today and I'm still not sure I understand it, as it seems to be connected-up a lil' strange (pardon my ignorance). I've re-drawn it in a way that I can understand(!), viz: ...and obviously, it's connected differently to your version... but it fits better with what I know of LPFs/HPFs... and unless there's some issues with interactions of the two 'modules', it seems to fit with one of the references I've been working through: Electronics Tutorial about Passive Low Pass RC Filters (which also has an explanation of High Pass Filters). Then again, I can almost understand your layout if I think in terms of the standard wiring on a Strat, as it's like the tone controls are 'in parallel' with the main signal line, so that's kindof how your layout works... I think. Anyway, I think I'm getting closer to the mark in my understanding... Fanx! John
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Post by sumgai on Dec 2, 2009 1:19:07 GMT -5
boomer,
OK, it's time to put on my Uncle Elmer hat. (Look it up, it's old jargon.)
As we look at the action of a capacitor, it tends to react to a voltage such that it wants to allow electrons to pass through it until it is saturated with them. Another way of saying that is that is that it charges up with electrons until it reaches equilibrium - both sides have the same number of electrons.
Now, in a DC circuit, that means that the capacitor will charge up (accept electrons) until that steady-state is reached, and then it will accept no more. This is an effective way of blocking DC from getting from Point A to Point B - in fact, when we use a cap in this fashion, we call it a blocking capacitor.
But we don't have to worry about DC inside our guitars, and we want tone, which is another way of saying AC. Right. Capacitors don't block AC, that's true, but they do react in some amount of time, or IOW, they don't react instantly, not to any frequency, let alone all frequencies.
So, what kind of time are we talking about? And the answer to that is, time is the inverse of frequency. (Perhaps you've heard that one before.) A cap reacts more slowly as the frequency decreases. This is easy to remember, if you recall that part about blocking DC - the lower the frequency, the closer it gets to zero Hertz, and thus the closer it gets to reaching equilibrium. Since our cap is reacting more and more slowly as the frequency goes down, it reaches a point where it just "stops"..... it doesn't react quickly enough for a frequency to pass through it. In essence, it reaches something like equilibrium, so far as our ears can tell. For all practical purposes, and all that.
Which is to say, we can now choose values that will let us use a cap in at least two ways (well, technically, one cap for each way) - we can bypass some of the frequencies to ground, effectively removing them from our hearing (that's a low-pass filter), or we can pass only those frequencies through that are high enough to "make the cap continue working all the time", or IOW, it always reacts. This is our classic high-pass filter.
But in that last case, how can we control it? Nothing could be more simple - we bypass it! Yes, we make the signal go around the cap, in this case through a variable resistor (the potentiometer), and that's how more (or less) signal is affected by the capacitor.
To summarize, when all the signal is going through the cap, we have a "filtered" signal. Only those frequencies and above that prevent the cap from reaching equilibrium will be passed. But when we want to alter that action, we can partially bypass the cap, allowing some of the remaining frequencies (the lower ones, obviously) to make it around the cap by going through the pot. Since the pot is blending, or mixing, the two amounts, we get (or should get) a fairly smooth response, hopefully pleasing to our ears.
And that's how the big boys do it! ;D
HTH
sumgai
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Post by ozboomer on Dec 3, 2009 6:12:54 GMT -5
[...sumgai's discussion about 'equilibrium', amongst other things...] HmHmm... I sorta understand that... and the light is starting to dawn somewhat... but even so... From your notes and some other things I've been reading, I think we have something like the following for a low-pass filter... - We have a cutoff frequency, Fc, that is a function of the values of the resistor and the capacitor (forget the complex arithmetic, calculus and all that - I surely have!)
- (AC) signals into the filter at a frequency below Fc 'change direction (polarity)' such that the capacitor can't react quickly enough and the circuit through the cap is effectively 'open circuit', so the signal won't go through the cap. and it gets to the output unaffected.
- (AC) signals into the filter at a frequency above Fc 'change direction (polarity)' such that the capacitor DOES react quickly enough and the circuit through the cap is effectively 'short circuited', so the signal prefers to go through the cap. to ground, therefore preventing signals at those frequencies from getting to the output.
- There will be some relationship involving the time constant (R*C) that governs how quickly the capacitor reacts above Fc, thereby giving us the classic 'ramp' frequency response of the circuit.
Even if that thinking is correct, it still doesn't really help me determine component values that will let me select a cutoff frequency between 80Hz and 700Hz(!) *Thinks*... I can use Fc = 1 / (2 * Pi * R * C) (transformed) to get a combination of R & C for ONE frequency (R = 240k and C = 910pF gives ~730Hz)... and then change the resistance value to get the other frequency (R = 2M, C = 910pF gives ~87Hz)... but how do I configure the resistor (or pot) to give that variation in resistance? This is why I included that extra resistor in the original layout I posted, so the resistance would range between two non-zero values, thereby causing the cutoff frequencies to also range between two non-zero values... or so I thought! Still exploring and studying...
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Post by ashcatlt on Dec 3, 2009 12:59:19 GMT -5
First question: Are you seriously wanting to make a notch/band-reject filter out of this thing? You specified: Anyway, after all this, I worked out that I like the LPF to track from 80Hz - 700Hz... and the HPF to vary 1000Hz - 15000Hz. Between the two, especially at the extremes, you'll be notching out about all of the usable frequencies in the guitar signal, leaving just mud and harsh. You'll also end up severely attenuating the entire signal, requiring a whole bunch of make up gain thereafter. I think you've got your H's and L's confused.
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Post by ashcatlt on Dec 3, 2009 14:28:34 GMT -5
Couple other things: Your idea to use a fixed resistor in series with the variable one to set max and min points is right on. This is exactly the right way to do it. In case you find it difficult to find a good value for the variable resistor, you can sometimes calculate a value of fixed resistor to put in parallel to change its overall value. This will change the taper a bit, though. Now, when trying to calculate the values for your filters, the big problem I always run into is: "Which R, and which C?" I can tell you that no single component in the circuit stands by itself. The Volume control, for example, will have an effect on the tone - the reason you've added the "treble-bleed" thing. I know (thanks to JohnH and ChrisK, mostly) that when talking about the normal Tone control in a passive guitar, the C that matters most for the majority of the travel of the variable resistor (it's not being used as a potentiometer in this instance) is that of the cable, which is in parallel with the signal - between "hot" and "ground". The variable resistor serves two purposes, as I understand it: 1) it isolates the actual Tone cap from having much effect on the signal until the resistance gets pretty small, and B) Being in parallel with both the pickups and the amp input, turning it down reduces the total resistance of the circuit... ...uh, oh. I really thought I could explain this stuff, but now I'm all confused. Seems to me like if the R decreases, the denominator of our little formula also decreases, causing the cutoff frequency to get bigger, for the same reason that while 2 < 16, 1/2 > 1/16. But, if this is an LPF, then this should allow more treble through, and we know it doesn't. Likewise we know that plugging into a bigger load (lower input-Z) will cause treble loss, but that doesn't really make sense for the same reason. So, at the risk of adding my confusion to your own, I'm going to call out for some help on clarification on this. Please? Thanks. Anyway, if you stick those filters between a couple active stages, it'll be a lot less complicated trying to figure your cutoff points. If you really are notching the thing, rather than band-passing, you're going to want a booster stage anyway...
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Post by JohnH on Dec 3, 2009 14:59:05 GMT -5
If this is to be part of pssive wiring in the guitar, then I think Sumgais diagram is the best way to get treble cut and bass cut controls. You'd have to play with values - I reckon the volume control might be best at 500k and the 5nf be more effective at about 1.8nF. The reason this diagam is good is because with all controls at max, it is the same as just a conventional arrangement where the pickup signal does not need to fight its way through any R's and C's to get to the output, so there is no unusuay losses. At maximum, the bass control is just a direct link. There is a high chance that if you try this out, you might not might not find the bass cut option to be a compellingly great sound that you want to have, but there's no harm in trying. Other interesting pasive circuits include putting an inductor in the tone circuit, and GuitarFreak2.2 will let you play with that (see link in a sumgai post above), or bypassing one of your pups with a cap when in series. Most tone circuits however, cause some inherent losses of signal and so are only useful with some gain stages around them. If you go that route, then the world of weird tone controls is wide open. Duncans Tone Stack Calculator is a great tool for trying a bunch of them. Out of those, my favorite is the Bigg Muff, which you can tweak by adusting all the resistors, to give mid boost or cut, or treble or bass emphasis - provided you then add about 10db of gain. I used it in my piezo circuit to equalise the transducer signal. John
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Post by ozboomer on Dec 3, 2009 19:41:15 GMT -5
Are you seriously wanting to make a notch/band-reject filter out of this thing? Well, I know it sounds weird.. but I think that's what I want to do, at least according to how the VSTs behaved. I don't care about anything <80Hz or >15kHz (can't hear them), so those values should be the ends of the runs for each of the tone controls. Let's have a look at a picture... and let me just write this out a minute: - Bass (LPF): When knob is on '0' (Fc=700 Hz), we pass the frequencies from 700+ Hz (up along the 'ramp') down to 80 Hz (our limit) and below (inaudible), which sounds relatively 'bright'. When knob is on '10' (Fc=80 Hz), we pass the frequencies around 80+ Hz (up along the 'ramp') and below (inaudible), which sounds relatively 'dark'.
- Treble (HPF): When knob is on '0' (Fc=1 kHz), we pass the frequencies from slightly less than 1 kHz (up along the 'ramp') up to 15 kHz (our limit) and above (inaudible), which sounds relatively 'dark'. When knob is on '10' (Fc=15 kHz), we pass the frequencies from slightly less than 15 kHz (up along the 'ramp') and above (inaudible), which is relatively 'bright'.
Note that this arrangement would require the pots to be wired differently for each of the 'Bass' and 'Treble' controls (clockwise = increasing resistance for 'Bass' and decreasing resistance for 'Treble'). To be 'conventional', I should probably fiddle with the VTS again and try to set things up as a band pass filter (rather than a band reject filter)... but I'm not sure that will give me the slightly 'nasal' sound I want at times. ...and certainly, I'd agree there might be some justification for a gain stage (hence the investigations into the preamp in this thread)... but if I install a chunky volume pot, I think I'll be Ok (according to Mr Torres, anyway!) On the other hand, maybe I'm better off sticking to the breadboarding of the various tone control options as detailed in the Tone Stack Calculator that JohnH mentions. It's just that I didn't seem to get much variation from the standard passive tone control when I tried those layouts and that's why I started looking at the LPF/HPF combination (and via VSTs). Heck. This is all going waaay beyond 'simple'... For now, I might try breadboarding sumgai's layout and hopefully, I'll hear something I like... and if the sound doesn't inspire me, I'll go through the various passive designs again (for now)... maybe even look at this option at TDPRI... and then hit the preamp again. Thanks again, folks. Time to bury myself in wires for a while rather than in books... John
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Post by ashcatlt on Dec 3, 2009 19:49:03 GMT -5
What are you running through this VST? BTW - those "G" plugs are all really cool for free. No nonsense, not particularly exciting, but they just plain work.
Keep in mind that the HPF is attenuating even those freq's which are passed by the the LPF, and vice versa. That means that everything is attenuated, and most of the freq's which are actually generated by the guitar are attenuated even more. So it'll take a bunch of gain just to get back to the original level.
Nobody's got any info on my little connundrum above? Let me check that link SG posted above...
Edit - Wanted to mention, too... There was a thread a while back where somebody (wanna say it was fobits) found that we could affect a more dramatic bass-cut by using the pot as a pot rather than a variable resistor. Basically, you'd wire it like a volume control with treble bypass. Of course, you'd probably want a "stop resistor" so the output doesn't cut out completely.
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Post by sumgai on Dec 3, 2009 21:33:23 GMT -5
I'm beginning to see the reason for all this confusion. ozzy, what you really asking for is a state-variable filter, in fact you apparently want one each for low and high passbands. What the rest of us have been working with are static filters - they have one, and only one, cutoff frequency. At this point, all you can control with these passive circuits is how strongly you cut those frequencies above (or below) the cutoff point(s). What you charted shows that you want various cutoff frequencies, and that's not gonna happen in our simple circuits. Why not? Because as you noted earlier, the RC time constant is what needs to be changed, and that isn't what's happening in the designs we've shown you so far. Putting aside for a moment the arguments about passive versus active, you need to modify the RC time constant with both components, not just one. As noted throught time immemorial, changing the resistance alone merely reduces (or augments) the level of the affected frequencies - but the "knee" of the curve doesn't move (appreciably, at audio frequencies). Accordingly, you need to bring in at least one additional capacitor.... which, if you've been paying attention, is exactly what the Gibson VariTone circuit did, way back when. Others here have concocted enhancements to this basic circuit, over the life of this Forum, but when it's all said and done, you're looking at selecting a different value of capacitor in order to move the cutoff point in the graph. You can do one of several things, at this point. Me personally, I'd give a good thinking towards using a parametric equalizer. Those are the state-variable puppies I mentioned early on. You set the cutoff point and the "Q" (how steep the curve is), and off you go. In fact, somewhere around the old homestead, I have a 4 passband parametric eq box that I built for a stereo system, circa 1972. (That was 2 controls per side, but they were not ganged, nor were they restricted in their specs. I could just as easily hook up all four sections to one signal, which I did for my guitar.) They aren't small, unless you can hire some of those famous elves that live in Der Black Forest to come and assemble them for you, but they can be built pretty cheaply. And they don't require a big amount of boost to get back to normal volume levels, unless you go Nutz.... er, wait... nevermind. Order a battery box and a couple of JFET's while you're at it. Next, you could just clone a VariTone setup, that's been done often, and is pretty much a proven fact. (i.e. It Just Works.) You could go digital. (!) Switched capacitor designs are simple, low parts count, very low current drain on the battery, and also tend to Just Work. But if you're a Tone Nazi (sorry, Mike), then you'd have to admit that "this ain't the way (insert favorite guitar hero here) did it, so I can't do that either", and thus you don't have to investigate this particular bit of tasty engineering. Consider this option a state-variable circuit on steroids. There are other ways to do the job, but right about now, I think it's time to kick back and re-assess your goals. If you're really out to get a variable frequency response curve, then everything we've discussed previously in this thread is now null and void. If you now think that you've been over-reaching, or just maybe, perphaps, you could have been confusing some terminology, then that's cool, let's all sit down and square up our terms, and then see what percolates to the top. HTH PUNT! Your turn! ;D sumgai
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Post by sumgai on Dec 3, 2009 21:35:52 GMT -5
ash, Sorry, I'm about outta time, and gotta run for the evening. I want to answer your questions, and if no one else does by this time tomorrow, then I'll see what I can do to help you out. Remind me, if it looks like I'm suffering from another bout of CRS. sumgai
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Post by ozboomer on Dec 3, 2009 21:57:12 GMT -5
A Year 11 teacher always asked me, 'Why must you make everything unnecessarily complicated?' I guess he was right. ...and worse, I tend to do it when I'm trying to make things simple.
Dang.
I had also been looking at active filters, FDNRs, op amp-based filters, etc, etc... and was thinking about the parametric EQ... but this is all MAJOR overkill for inclusion in a guitar, methinks...
So, as I say, I'll go and bend some wires for a while after work today.. and see if I can't find something that IS actually SIMPLE and yet gives a bit of something different in terms of tone.
Still keen to see what thoughts we come up with.. (I'm determined to get some modules developed after all this!)
Fanx!, all...
John
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Post by ozboomer on Dec 5, 2009 0:35:00 GMT -5
As the experiments continue along... Has anyone tried the so-called Gibson '50s Wiring in a Strat? As I've been trying a few things today, I thought I'd try placing the tone control portion after the volume, akin to what's shown in that link... and things certainly sounded a bit clearer and brighter... although, in some further experiments, I've found the 'treble bleed' would still need to be installed across the volume pot -- everything still 'dulls off' when the volume is down, even 'post tone control'. Still, I'd like to know if anyone else has tried it out... and to get your thoughts on it. I tried looking for something about it on our site here but couldn't find anything related to it... probably my searching is not very creative (today) Ta, heaps. John
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Post by sumgai on Dec 5, 2009 13:41:18 GMT -5
ozzy, We've discussed the Vintage Gibson wiring topic, there's even a sticky posting for it, as started by our own venerable JohnH. Try this: Modern and 50's WiringHTH sumgai
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Post by JohnH on Dec 5, 2009 13:46:35 GMT -5
When I first bought and old strat copy off ebay, it was in fact wired that way, probably by mistake, but the tone control was very bad - didnt like it at all. The effects described in this post would still apply: Modern and 50's wiringThere is no difference at full volume however. So why don't you give it a go? John .
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Post by ozboomer on Dec 28, 2009 5:08:22 GMT -5
I've been spending this last many weeks experimenting with some passive tone control designs and in short, I've had precious little joy with the things... Without going through the gory details, I'd decided on exploring the sumgai design in a bit of detail, viz: ...and my explorations finished today. Certainly the 500k pot/0.022uF cap component works well... but the 'Bass' element seems to do nothing sonically. I tried various cap. values (the 5nF, the 1.8nF JohnH suggested, as well as most other 'broad range' values) and I couldn't hear it doing anything. Fair enough, that a few extra frequencies around 50 Hz were NOT cut (according to a software/VST spectrum analyzer - my CRO is too old and I've forgotten how to work it) but I sure as heck couldn't hear anything different when I used the 'Bass' pot. 30/12/09 [edit] I've tried breadboarding 5 or 6 extra passive designs in the last couple of days, that all have a similar section where the signal goes through the capacitor, to supposedly modify the 'bass' response and none of them seem to do anything. Here's an example from diystompboxes.com that I built-up and even using the suggested values for the 'bass' side, I hear no changes at all, nor see anything really significant on the software spectrum analyzer. I've tried different pots and things, in case I have dud components but none of the 'bass cut' -type things seem to work... grrr.... [end edit]If I tried placing a classical HPF ahead of the LPF section alone (removing the 'Bass' part of the circuit shown here entirely), all the signal was blocked and I needed to crank the volume too much, so that simple arrangement won't work. In short, the 'treble' part of the sumgai design seems like all I'll end-up using; the other 10 or so designs I tried all seem to do nothing, in various ways, so there doesn't really seem to be much point... unless someone can suggest a passive section/layout that can somehow strip the low frequencies out effectively... Now, if I was using an active design, I think things would probably be different... but I don't know if there's any point in pursuing that, given that I'll probably do something with amps/mixers/recording software(VSTs) anyway. *shrug* Anyway, just thought I'd drop through an update. I'm at the stage of ordering parts and starting some basic surgery on a couple of strats in the coming weeks, which will incorprate the mods detailed in this thread.. so I'll keep a'postin' the details... John
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Post by ozboomer on Jan 12, 2010 5:48:58 GMT -5
I've reached the 'completed' stage, now, of an early (and modified) version of this mod, so I thought I'd put it up here... and leave it to others to decide whether it warrants being placed in the 'General Guitar Schematics' board as a complete design; I'm hoping the follow-up design will be - I'm looking to get onto it in the upcoming months. The Constructed DesignSome explanatory notes on this design: - It's been derived from my on-going series of 'modules' currently being developed. A lot of them are not Earth- shattering but they don't appear in the 'Design Modules' sub- board (yet!), so I'll end-up posting them at some stage.
- It uses my original idea of a simple 1- or 2-wire addition with a toggle switch, so that the Neck & Bridge pickups are always on. After much discussion in this thread, I've found there's a bit more useful/less 'redundant' way of achieving the same result but I'll incorporate something like that in one of the subsequent designs, I think.
- I was thinking about trying a phase-change switch in this design, viz:
...but as the middle pickup in this arrangement is RW/RP, simply swapping the hot/cold leads on the pickups wouldn't have made any changes in the sound (I think), so there was no point in including the phase switch here.
- At the last minute, to cut-down on the wiring I needed to do, I decided to leave the volume and tone pots alone. This means the following tone control module was NOT included (I opted for the simpler 'single pot' tone control instead):
NOTE: After trying perhaps 10 different passive tone control designs, I found that, in general, none of them really did anything significantly better than a single pot/cap combination.
- I used a cheap (A$50) pre-loaded pickguard that I bought on eBay for the project. It included ceramic pickups, pickguard, back cover, pots, switch and wiring. I never installed it 'as- supplied' so I don't know how it worked when it first arrived (I admit I don't particularly enjoy going through the string change thing, even if a set of cheap strings is only $5, it still takes me 40+ mins to change the strings...!)
There were a few things I learnt as I was developing/trying-out this design: - Theory is all well and good but unless you have some 'serious' lab equipment, it seems the best way to evaluate a design element is to build it, vary the component values and use your ears. I tried MANY arrangements of tone controls and basically found most of them did nothing special. In a way, it's a waste of time... but hopefully, these sorts of notes and discoveries will be included when we post entries in the 'Design Modules' sub-board.
- Do plenty of research regarding the actual gear you're modifying and about the parts you're planning to use. MUCH of the hardware made for a Standard Stratocaster will not fit a Chinese (Bullet/Affinity) Stratocaster... and realize many of the (supposedly well-reputed) on-line retailers are NOT interested in researching the info on their own stock for you.
- The old maxim 'you get what you pay for' surely holds true, I think (see below). I would probably have been better-off getting separate components and building something up from scratch... but I have to get the $$$ thinking out of my head, I guess. How sensible(?) IS it to spend $200 on pickups and a replacement pickguard for a guitar that cost $160?!
ImpressionsOverall, the project went pretty well... but I'm kind-of disappointed with the result. The sound is pretty uneven; when I strike a single string, it sounds like a metal rubber band(!)... and it booms a bit at times. There's also a somewhat grating 'twang' in the sound that sounds like a bad harmonic or something (this is not a 'good' twang, like we'd want to hear when playing Instro Surf, for example). The ceramic pickups I had installed were the originals that came with the Bullet and they sounded much cleaner and 'smoother', I'd say... There are also some problems with the installed 250k pots, I think. It could be my soldering but the joints looked Ok and tested out Ok when I first installed the modified pickguard (with only one string installed). Most of the time, the tone control doesn't work. Nothing happens as I turn the tone knob... but if I *bump* the control, it will 'come good' and the high-end roll-off happens Ok... for a little while. I tried the electrical lubricant and that didn't do much. So, at some stage, I'll pull the thing apart again and try installing the 'real' components instead of the ones that came on the loaded pickguard, just to see that everything works properly... Then again, I might not worry about it now... and I'll get on with the next development in this lineage(!) Anyway, for your consideration, folks... John
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Post by newey on Jan 12, 2010 6:47:09 GMT -5
ozzie- I don't know if you caught my post from last week on the Schaller tone circuit, which uses a switch instead of a pot for HPF and LPF, or both at once: guitarnuts2.proboards.com/index.cgi?board=wiring&action=display&thread=4665Somewhat similar to what you were attempting here, albeit not variable. Anyway, you might look at the circuit, since by all accounts, both filters do have a real effect in that design. And: We're had this discussion many times. Swapping the leads on a RWRP pickup will indeed put it OOP with the other pup(s). You will lose the hum-cancelling, however. At the risk of having Sumgai trot out his "beating the dead horse" smilie, I'll reiterate the thinking on this. There are 3 factors affecting the AC phase of a pickup's signal: 1) The direction of the vibrating string; 2) The magnetic polarity of the pickup's magnets (South pole vs. North pole); 3) The winding direction of the pickup (which is reversed by swapping the hot and cold) Changing either one, or all three, of those things results in an OOP signal. Changing any two results in the pup being back in phase. (Think of changing any one factor as doing a 180° rotation; changing 2 things brings you back to 360°) #1 above, the vibration of the string, can't be changed (since we have to be able to play the guitar), which leaves altering #2 or #3 as our only real options. A RWRP pup is in phase with a non-RWRP pup because both #2 and #3 have been changed. I won't get into how it cancels hum, just know that both factors have to be opposite the other coil(s) for it to be hum-cancelling. If you then swap the leads (thereby changing #3 back to match the other pups), then one factor, the magnetic polarity, is still different, and an OOP situation results.
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Post by ozboomer on Jan 12, 2010 7:40:22 GMT -5
I don't know if you caught my post from last week on the Schaller tone circuit, which uses a switch instead of a pot for HPF and LPF, or both at once: Nope.. but it looks interesting for the fact there are no resistors at all... (my weak electronics asks:) Will that improve the loading on the pickups == less losses from the HPF section? I'll certainly put it in my box of tone tricks... Fanx! Oh... and BTW... What are the "R" and "M" about in that circuit? Something like a 'bright' switch, I'm guessing... [...about the RW/RP...] Hmm... I think that when I was researched that option, I only saw "no hum cancelling" and that knocked it on the head, given the "thin-ness" of the OOP sound. Anyhoo, I'll make a note, thanks (and neither do I wish to incur the Wrath of SumGai)... John
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Post by newey on Jan 12, 2010 11:27:28 GMT -5
It's not wrath, SG loves using his smilies . . . And I don't know what the "R" and "M" switch does, either, but your guess looks like a good one. There were 3 versions of this circuit, and the others did not feature that switch.
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Post by sumgai on Jan 12, 2010 15:47:35 GMT -5
Guys,
"R" and "M" probably meant "Rhythm" and "Meister" (or lead, as in 'master'). But what do I know....
HTH
sumgai
* Note that no smilies were harmed in the making of this post!
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Post by ozboomer on Jan 14, 2010 4:04:43 GMT -5
I've had some more thoughts here, as I've been fiddling about with this modified guitar... I was playing the guitar without any amplification and was listening carefully to the sound... and I noticed the 'nasty twang' I was hearing when I first plugged it in is still there. So, perhaps the problem isn't in the pickups but might be the strings themselves; I certainly don't recall hearing this sort of 'grating' sound with the strings that were on previously (although, they were the same brand). I fully admit my ignorance, here... Perhaps the sound of similar string sets CAN be totally different, can they? ...particularly with cheap quality strings; I expect consistency of sound quality is one of the things you pay the extra $$ for, eh? So, maybe I'll re-think things again... and have a go at replacing the strings (maybe I'll just have to lash out on the A$13 strings!) before I start worrying about new pickups... and, while I'm at it, I may as well fix the dickey pot, etc Heh... It's one of the things I'm constantly fascinated by, with all these mods we fiddle with: how many ways a project can be revisited and tackled in different ways... Whee. John
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Post by sumgai on Jan 14, 2010 17:26:26 GMT -5
boom-boom, Does this guitar by chance have a vibrato bridge? If so, then it's possible that you're hearing the springs resonate with certain frequencies as you pluck the strings. Quite audible when played 'unplugged', and sometimes it can be heard when you're plugged in. If you're running "hard tail", you might check to see that all of the bridge saddles are sitting solidly and squarely on the bridge plate itself. Sometimes one of the two screws will be 'just resting' on the plate, making it 'look good', when in fact the contact is nebulous at best. (Applies to vibrato bridges too, of course.) Other than that, I'd have to second the suggestion that you try a different brand of string, or at least a different gauge. Just a few thoughts that somehow crossed my mind...... HTH sumgai
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Post by ozboomer on Jan 17, 2010 18:22:55 GMT -5
...I noticed the 'nasty twang' I was hearing when I first plugged it in is still there. So, perhaps the problem isn't in the pickups but might be the strings themselves; Mr SumGai: I had a look to see if the tremolo springs were resonating and they didn't seem to be moving; I couldn't see nor feel any vibration through them. This Squier Bullet has a vintage-style (6-screw) bridge and die-cast flat saddles... and the bridge is 'almost' floating but it's not really hard against the surface of the guitar; probably more like 'lightly touching'... At any rate, I spent some many hours this past weekend fiddling about with this guitar... and I'll spare everyone the blow-by-blow description. Suffice to say that I ended-up replacing the 12mm tone pot with a 25mm, 250k log version, as the little one seemed to have some sort of short at the end of its run. The tone control works pretty well (although there is some sort of anomaly - see below)... and I changed the strings to another set and the guitar sounds Ok now. Not exactly the same as before (I think) but I can control how it sounds pretty well. An interesting observation, though, that perhaps could be explained by our resident experts... Something I first noticed on my Squier Affinity Strat and seems to be stronger on this Bullet with the new capacitor value (0.0047uF) being used through only one pot. When the pot is turned fully clockwise (on '10'), we get close to a 'straight through' sound with maximum treble. As the pot is turned anti-clockwise (towards '1'), we start stripping out the higher frequencies... and 'normally', I expect that would just make the sound become increasingly 'duller'. However, with the combination of the 250k pot/0.0047uF cap, my *ears* tell me this 'dullening' happens until we reach about '5' or '4'... and then the sound goes quite 'nasal' as we approach '1', which I'm guessing is some sort of 'notch' thing happening. Now, I don't mind this, as this is one of the sounds I was looking for (to use in a funk/rhythmic situation)... but it sort-of throws out the simple RC theory that I've been trying to understand in recent months... and I'm wondering why it happens...? Anyway, this finishes-up this SimpleMod for now... and, as it's basically little more than adding a simple 'B+N on' switch, I think I'll relegate the 'project' to the module postings I plan to do. I've been re-thinking the series blending project again, and I'm making more compromises, etc so I'll start-up another thread on that at some stage. Fanx! again for everyone's help and comments. John
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