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Post by lookbunnyrabbit on Nov 10, 2015 15:05:41 GMT -5
I found this while looking around for a tone circuit with both bass and treble to add to my telecaster. www.aaroncake.net/circuits/tone.aspIt looks to be a very compact circuit that will run on 9-15v dc and easily fit most guitars. |
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Post by sumgai on Nov 11, 2015 13:00:22 GMT -5
rabbit, Several things... 1) You do realize that this thing, and particularly your diagram, is made for stereo use, yes? That's an immediate flag that says "cost overrun". Unless you can repurpose one of those two channels, then I'd suggest that you consider a less expensive solution. 2) This is not a simple, low-parts-count circuit, trust me on that one. Even accounting for only one channel, there are still more parts than absolutely necessary for your stated goal. 3) The chip-in-question, a TDA1524A, is almost 30 years old. That's not necessarily a bad thing in and of itself, but I'd like to think that we have come a long ways since then in producing much better products, both in terms of sound quality and in pricing. 4) Here's where we get technical. Since you're on a tear to learn "all" about electronics, go get a beer and a sammich, and kick back - you're about to get an eyeful.  An amplifier does what we expect, it amplifies a weak signal into a stronger signal. A circuit that controls the frequency response (a tone control) does the opposite, it reduces the output to some degree. How much, and more importantly, how noticibly, that's up for debate. Even so, we can compensate for that reduction by... wait for it... inserting an amplifier into the same signal chain as the tone control(s). That's it, in a very tiny nutshell. All tone controls are passive, but we can compensate for their effect on volume levels by providing amplification, either before or after the actual controlling circuit. In some cases, we see amplifier stages both before and after, and that's OK, nothing wrong there. In fact, we usually need several stages of amplification anyways, so where the tone controls go doesn't matter in that regard. However... Lemme address the thing about 'active' tone controls. What you're really seeing is a "black box" approach, even if all the individual components are laid out on the diagram. In essence, a short analysis will reveal that active components are simply amplifying a tailored portion of the frequency band, and that there will be a passive control (for the user to play with) somewhere in there. Because a transistor or tube is used to amplify only a portion of frequencies, instead of the whole 20-20,000 Hz thing, people (not Engineers) call that 'active'. Well, who am I to pee in their Cheerios... they can call it whatever they want, but the Engineers who design these things from the ground up, we know what's what. So, the final breakdown for you is this: a) Check out the rest of the forum wherein you've posted this thread. Many threads detail exactly what you're looking for, and with a much simpler approach. (Not to mention, less costly, and easier to troubleshoot, should the need arise.) b) Full frequency audio amplification and control (meant for reproducing music, as opposed to producing music) is not always the best thing for guitar circuits. But that's a lesson that's hard-won for most non-Engineer types, so don't beat yourself up over it. Trust me, I'm not gonna be casting aspersions on you for falling into that particular trap. c) Numerous other things flit across my mind here, but I think the best closing point I can make is this: We may be Nutz here, but we do believe in the K.I.S.S. principle. Even I have stopped inhaling all that FelderGarb about "more's better"!  HTH sumgai |
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Post by ashcatlt on Nov 11, 2015 15:36:34 GMT -5
I don't agree with the assertion that every "active" filter is about passive attenuation of unwanted frequencies followed (and/or preceded) by amplification. There are any number of circuits where the filter action is intrinsic to the active amplification stage and just plain won't work at all without it. They may use some of the same components and principles as typical passive filters, but often with drastically different results.
I do agree that there are better, easier, cheaper, and lower parts count solutions that don't involve trying to source a monolithic "tone control" chip. For separate Bass and Treble controls that are actually tuned for guitar, I would start by hacking a Vox tone stack in between an opamp buffer and a simple opamp recovery amplifier (this would be what sg is talking about with attenuating via passive filter and amplifying back up). Use a TL072 and it's still a single IC, with several less parts, and will be about half the physical size.
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Post by lookbunnyrabbit on Nov 11, 2015 23:41:35 GMT -5
Yes, the project in question is a tele that I am trying to build stereo (just for learning purposes)
a) Check out the rest of the forum wherein you've posted this thread. Many threads detail exactly what you're looking for, and with a much simpler approach. (Not to mention, less costly, and easier to troubleshoot, should the need arise.) Thank you, I have been reading quite a lot the last few days.
b) Full frequency audio amplification and control (meant for reproducing music, as opposed to producing music) is not always the best thing for guitar circuits. But that's a lesson that's hard-won for most non-Engineer types, so don't beat yourself up over it. Trust me, I'm not gonna be casting aspersions on you for falling into that particular trap. I had no idea on that. Is that because its too detailed thus adding or picking up unwanted traits?c) Numerous other things flit across my mind here, but I think the best closing point I can make is this: We may be Nutz here, but we do believe in the K.I.S.S. principle. Even I have stopped inhaling all that FelderGarb about "more's better"! They do say better is the enemy of good
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Post by sumgai on Nov 12, 2015 1:13:36 GMT -5
rabbit, Yes, the project in question is a tele that I am trying to build stereo (just for learning purposes) Well, I don't recall reading anything about a stereo geetar in the preceding postings.... Never mind, my bad. No, not particularly. The main reason is, right at the heart of the matter, cost versus bang-for-the-buck. In hi-fi work, stereo or otherwise, we need to spend more in order to get good quality audio over the entire audio range, and with the lowest possible distortion rates. In guitar work (and other "live" instrumentation), we don't need nearly so much frequency range, and we often desire some degree of distortion, which in turn means that we don't have to spend as much (on a per-circuit basis) to get what we're looking for. I'm not saying that anything and everything that uses more than two parts is 'too complicated', I'm merely saying that each and everything has a place and a time where it will be the right thing to do/use/have/whatever. In our line of work, we most often find ourselves quite capable of assuming the role of 'music maker', but rarely able to assume the role of 'electronics wizard'. That's the sole reason I tend to espouse the K.I.S.S. principle - troubleshooting is always easier when the parts count is no higher than the minimum to get the job done. That's it in a nutshell, hope it was a satisfactory explanation. sumgai |
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Post by newey on Nov 12, 2015 6:32:26 GMT -5
bun-
I, too, am building a stereo Tele, although actual work on the project has been stalled for a few years now, as competing demands on my time have overwhelmed most guitar projects. But my version doesn't have any active amplification going on.
I question your original statement that this will "easily fit" in any guitar. It has 4 pots; even if you were to use concentric pots, it's a tough fit in a Tele cavity.
On my (passive) stereo Tele build, I have the equivalent of 4 pots (4 knobs, anyway) - it has a master (dual-gang) tone, individual volume pots for each channel, and a rotary switch for pickup selection, plus dual output jacks for the two channels. I've had a devilishly tough time getting all that stuffed into a Tele cavity. If it were just the components themselves, no problem, but of course there is a veritable bird's nest of wiring running to each of the components. I've spent many hours carefully routing each wire and with each test-fit into the cavity I seem to stress one or another of the connections.
So, adding active electronics? I'm not seeing that, unless this particular Tele is in line for some radical surgery in the cavity. On a Strat, you can at least stash the 9V battery in the trem cavity, but there's nowhere else to go on a Tele.
So, before you embark on this, my advice is to measure for fitment carefully in advance. It won't do you any good to build this thing only to find that it won't fit the guitar.
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Post by ashcatlt on Nov 12, 2015 13:32:50 GMT -5
Well, if it's stereo we need a TL074, which isn't I think any smaller than your chip, but is still easier to find and cheaper.
What are those pots? Individual high and low for each side? I'd think that in a hi-fi they'd be dual gang pots - one high and one low on the panel. Can you get away with that or do you actually need them separate?
More importantly, why are you sticking batteries in your guitar? An "active" EQ is almost better in its own separate box on the floor or on top if the amp where you can plug any guitar into it.
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Post by sumgai on Nov 12, 2015 14:48:50 GMT -5
ash, Actually, in a stereo build, the TDA1524 might be a better deal. Reason being, it takes only one control to dial in the Treble or Bass for both channels at the same time. The user sees only a single knob (for T or B), but inside that glob of black plastic, the single control is changing a voltage that, in turn, controls the response curve for both Left and Right channels. In the name of external simplicity, this might not be so dumb an idea. However, some deep experimentation is gonna be needed to make this all work in an acceptable manner, or else the guitar's tonal characteristics are gonna be utterly destroyed. OTOH, if the user wishes to be able to control each pickup's Treble and Bass separately, then all bets are off. Not only will some serious real estate be needed on the axe, both above and below the cover(s), but the parts count is gonna be ridiculous, IMO. Might as well use a low-noise chip like you suggested, or to my way of thinking, a couple of John's JFET amplifiers would probably be a better fit for this project. 'rabbit, are you listening here?  sumgai |
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Post by lookbunnyrabbit on Nov 12, 2015 22:09:16 GMT -5
Well, if it's stereo we need a TL074, which isn't I think any smaller than your chip, but is still easier to find and cheaper. Ill look into the TL074. I am still just a tinkerer in electronics. Ive only built a midi in-out to 15 pin d-sub box, (about 20 parts) a DC voltage converter from 24 to 12 and numerous guitar schematics. What are those pots? Individual high and low for each side? I'd think that in a hi-fi they'd be dual gang pots - one high and one low on the panel. Can you get away with that or do you actually need them separate? Thats exactly it. I wanted to use stacked pots. (bass lower, treble upper)
More importantly, why are you sticking batteries in your guitar? An "active" EQ is almost better in its own separate box on the floor or on top if the amp where you can plug any guitar into it. Crap, the only reason I was thinking about this is that I thought that with it being inline (minus cables and connections) that it would be cleaner in the chain. If its really no advantage, I guess I would be better building this into a stomp box or see if "they" make a stereo EQ pedal. I have two jc120s and that is what inspired the idea of making a well refined stereo telecaster. ash, Actually, in a stereo build, the TDA1524 might be a better deal. Reason being, it takes only one control to dial in the Treble or Bass for both channels at the same time. The user sees only a single knob (for T or B), but inside that glob of black plastic, the single control is changing a voltage that, in turn, controls the response curve for both Left and Right channels. In the name of external simplicity, this might not be so dumb an idea. However, some deep experimentation is gonna be needed to make this all work in an acceptable manner, or else the guitar's tonal characteristics are gonna be utterly destroyed. OTOH, if the user wishes to be able to control each pickup's Treble and Bass separately, then all bets are off. Not only will some serious real estate be needed on the axe, both above and below the cover(s), but the parts count is gonna be ridiculous, IMO. Might as well use a low-noise chip like you suggested, or to my way of thinking, a couple of John's JFET amplifiers would probably be a better fit for this project. 'rabbit, are you listening here? Im still in it. Was in my hole looking up the TDA1524 as well. I think over all I would like the controls separate though. I tried to look up johns JFETs but the search function is not working for me. I looked around as well, no luck.sumgai |
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Post by sumgai on Nov 13, 2015 2:21:16 GMT -5
I tried to look up johns JFETs but the search function is not working for me. I looked around as well, no luck. Here ya go: guitarnuts2.proboards.com/thread/3150/jfet-buffer-cableIt's a long thread, been going on for years, so make some time for it. A lot of details, with newly registered members asking questions that sometimes cause John to make updates... so don't skip over anything. HTH sumgai |
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Post by ashcatlt on Nov 13, 2015 13:08:20 GMT -5
I suppose one advantage to having it in the guitar is that the knobs are right there and you can turn them without bending over or moving your hand too far from the strings. If you plan to change settings a lot in the middle of playing, it's something to consider. But are we still talking about four pots? Like, two concentric pairs? I'm thinking that's going to be tough to twiddle with one hand in the heat of battle.
Would you be up for something like a Tilt Control - one pot that gives high cut when turned one way and low cut turned the other way and (relatively) flat in the middle - for each pickup? This was very common in old hi-fi, and is pretty much the same idea as the Big Muff tone control that pedal nerds like to stick in everything.
Whatever you end up doing, I think we could actually have most of the components hanging off of pots and may not really even need a "circuit board" at all.
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