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Post by JohnH on Nov 30, 2010 3:29:07 GMT -5
Well based on the values above, I’m suggesting 120k and 0.82nF on each of the 250k volume pots. These values are each one step away from the ones I’ve been working out for humbuckers and 500k pots. With a single pickup selected, they seem to give a very good match of tone +/-1 db, from about 1 to 5 on the volume pot, within +/- 1.5 db from 0 to 6.5 and within +/- 2db through the full range 0-10.
With two pickups in parallel or series , the tones seem like they will stay balanced but the frequency of the peak will move a bit more. At full volume, parallel settings have a higher peak frequency and series ones are lower as compared to that of a single pup. As you turn down, these peaks look like they will move towards that of a single coil.
All quite interesting and fairly subtle changes, ie with those values the tones all look like they will probably sound good, ie without obviously unbalanced quantities of dullness or brightness.
So if you try them, I’ll be interested to know if your appraisal of the results matches the theory.
Cheers
John.
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Post by asmith on Nov 30, 2010 4:15:15 GMT -5
He's a Jukebox Hero... EDIT: I wrote that before you posted, but hit the button some time afterwards, evidently. Isn't there a movie about you? Thank you so much. I'll most definitely let you know. How did you conduct the experiments? Through software simulation, or do you have a hive of resistors, caps and pots in a secret room somewhere? Pretty sure there was a movie about that too.
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Post by JohnH on Nov 30, 2010 4:52:39 GMT -5
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Post by asmith on Nov 30, 2010 5:07:15 GMT -5
You're a gent.
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Post by asmith on Mar 22, 2011 18:43:27 GMT -5
The good news is, it works!The bad news is that it doesn't work. The shielding doesn't work as well as expected. There's still considerable hum. This is probably something really obvious like a bad connection from the shield to the circuit. I also taped over the shield with electrical tape to prevent shorts to the shield, as that was a problem when I first started reinstalling the electronics. My reasoning goes that this shouldn't make a difference because the metal shielding is still there, 'outside' the tape relative to the circuitry. Am I wrong? The DPDT switches work wonderfully. I suspected the dual-gang pot might be a bit CH, so when I first put the circuit together, I wired one level of the dual-gang pot on lugs 1 and 2, and the other level on lugs 2 & 3 (2 being the wiper lug). I figured, "Either they're both log taper, in which case one will be wrong and the other correct, and I can identify which one is wired backwards and correct it. Or, one will be anti-log, in which case we'll see what happens." It turned out I'd wired the log one the anti-log way, and the anti-log one the log way. Classic! Stan and Oliver would be proud. The bridge tone control works all the way until the end, at which point it zaps out and cuts the bridge. It sounds very much like this: Worse is the fact that the bridge volume becomes a variable resistor to ground. That's a Tone control which maybe doesn't get quite so dark toward the bottom, but turns the guitar off when cranked all the way down. But after triple-checking the damn thing, it all seems to be in order. Something I'm missing, a loose strand of metal or something. Infuriating. Thus, I've fixed the Neck+Middle Tone by swapping the input wire to the opposite lug. When I identify what the hell is going on with the bridge, I'll fix that too. However, for the moment, I have my baby back, and she screams. I'll pull her apart again in a week.
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Post by asmith on Apr 11, 2011 20:04:43 GMT -5
Almost done. I've swapped the bridge capacitor for a new one, but it hasn't solved the problem of cutting out the bridge when the tone is all the way down. Two dodgy capacitors? Does anyone else have any suggestions? I also modified the circuitry to this. I've simply removed the connection between the 'middle' terminal and the 'bridge' terminal on the right-most half of the five-way switch on the diagram. When the 'bridge in series' switch is not activated, this makes no difference. The guitar behaves as if it was stock wiring. However, in series mode, ripping the five-way switch back to the bridge position yields some interesting results. Before, both the 'Bridge' and 'Bridge and Middle' selections gave the same output. Now, the bridge now responds inversely to the 'neck and middle' volume control, and also inversely to the 'neck and middle' tone control. It's actually a great result. I love the tones I can dial in. It can go from a bright, blistering bridge down to a high-cut mid-punch bridge that's still unmistakeably a single coil. I think this is because that potentiometer becomes a variable resistor in series with the bridge pickup. When the volume control is turned down, and less impedance is put in series, the pickup acts more and more like a standard single coil. But since impedance affects different frequencies by different amounts, with more series resistance, higher frequencies are attenuated. It's not as obviously affecting to the tone as a tone control, but I like the effect. Similarly, I would think this means that the 'neck and middle' tone control now acts like a 'bypass capacitor' to the 'neck and middle volume ' resistance of 250k. As the 'volume' control is turned up, splitting more of the signal towards the cap, and the 'tone' control is turned down, increasing the effective resistance of the 'volume' potentiometer because of the concept of 'resistors in parallel,' and pushing more of the signal through the 'cap side' of the wiring, the scheme acts like a single coil bridge pickup with a capacitor in parallel. Crazy tones. I'd be greatly appreciate if one of the gurus could slap me round the forehead and explain exactly what's going on here if I'm wrong.
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