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Post by ashcatlt on Sept 5, 2009 10:59:33 GMT -5
This is for a co-worker's P-Bass. He's still sanding and finishing the thing, so it'll be a while before he starts wiring. Me, though, I've already got visions dancing around. I think I've convinced him to go with a split pickguard (something like a Jazz bass) so he can remove the controls and experiment/change/fix without near as much hassle.
Anyway, I'm thinking 2 P/P pots. One switches the 2 coils from series (standard) to parallel.
What I want to do with the other is basically move the "top end" of the tone control from where it normal is in "Master Tone" position over to the series connection. This should make it so that turning down the tone control will cause the low strings to darken up while the high strings get brighter.
I haven't put cursor to "paper" on it yet, but these are pretty simple modules as is. My problem is that this tone switch (in its current iteration) does pretty much nothing when the other switch is pulled. That is, in parallel mode it'll be Master Tone either way.
The question:
What kind of interesting things can we do with this switch when the other is in parallel mode? There will be one pole completely free to do with as we please. Is there a way we could convert the tone control to act as a master bass cut? What else might we do?
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Post by ChrisK on Sept 5, 2009 14:42:05 GMT -5
I'm not entirely sure how a P-Bass split pickup in parallel will sound. It should be fine, but usually when two coils are put in series or parallel, both are sensing the same string(s).  One could use the tone control to shunt the bass(er) coil with the tone cap. This would tend to reduce its harmonics while bypassing this coil with the treble(r) coil's signal and reducing its fundamentals. Finding an optimum value of cap would be interesting. I can say that having each tone control on my PadoukCaster (MR wiring) directly across the neck and the bridge respectively, with a 0.022 uF cap, gives a noticeable and pleasing shunting effect when the pickups are in series. I'm not sure that this tone control effect is needed as the switch from parallel to series effects an octave downward shift in the output pass band from the pickup. And in parallel, it's just the tone control. I might suggest the use of a true blend pot to effect a high frequency cut from "5" to "0" and a low frequency cut from "5" to "10". I've alluded to this several times with no "nibbles", if there is interest I would post a design. |
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Post by ashcatlt on Sept 5, 2009 21:23:38 GMT -5
I'm not entirely sure how a P-Bass split pickup in parallel will sound. It should be fine, but usually when two coils are put in series or parallel, both are sensing the same string(s). We're going to find out. I think it'll give a brighter sound overall thanks to the major reduction in total inductance. Yup, when it's in series mode, pulling the switch on the tone knob will do exactly this. When I mentioned it to the owner of the bass, his eyes lit up. However... Which means the switch on the tone control isn't doing anything meaningful in this mode. This is unacceptable to me, which is why I've started this thread. |
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Post by ChrisK on Sept 5, 2009 22:35:43 GMT -5
Well, I thought about it a little bit. The Duncan Duckbucker is a two half-coil (and half the strings) in parallel pickup, so the split P-Bass pickup should be fine. Going from series to parallel will reduce the inductance by a factor of four, thereby increasing the pass band resonant frequency by a factor of two (an octave, it's a function of the square root of [the capacitance times the inductance]). High Cut Low Cut Tone ControlAgain, a clever sort might see a way to select the high cut tone function or the low cut tone function on the DPDT push pull tone select pot. |
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Post by ashcatlt on Sept 10, 2009 0:22:28 GMT -5
Okay, I'm sure I can use a DPDT switch to change a "standard" high cut tone control into a low cut.
However, from what I can tell, this requires both poles of the DPDT. I need at least one pole of this switch to change the "position" of the tone control when in series mode. I'm having trouble getting the S/P switch to also change the function of this switch.
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Post by ChrisK on Sept 11, 2009 23:34:07 GMT -5
Yep. Likely. Not in this GeDankengang. This appears to infer that when in series high-cut mode, the high-cut tone function is a'shunting a half. This also seems to infer that when in series low-cut mode, the entire pickup is passing through the low-cut filter. Parallel high-cut - there is a high-cut RC tone control across the output bus. Parallel low-cut - there is a low-cut RC tone control in series with the output bus. Series high-cut - there is a high-cut RC tone control across one half of the split pickup. Series low-cut - there is a low-cut RC tone control in series with the output bus. This is four states. There are two binary switches.  Keep in mind that series/parallel actually requires only 3/4ths of a DPDT switch.  This isn't pertinent to this issue, I just thought that I'd mention it. (Oh, all right.  It requires a SPDT section for one pickup and a SPST section for the other.) This leaves a switching action available in the series mode. This means, with simple terminal redistribution, that something additional can be switched to signal ground, pickup hot output, or the center tap when in series. "Denken Sie es durch." In this GeDankengang, since there is the questionable desire to capacitively shunt one half of a split P-Bass pickup when in series, and to avoid such outrage when in parallel, the mere act of connecting the high-cut tone control across the shuntee will effect said shunting of one pickup half when in series, and both pickup halves when they're in parallel'ski. This requires 0 poles of a DPDT switch.  ;D Keep in mind that the act of using a normal right-hand taper high cut RC series tone control to shunt said pickup will have the effect occurring at the CCW end of rotation. |
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Post by ashcatlt on Sept 12, 2009 7:52:55 GMT -5
Parallel high-cut - there is a high-cut RC tone control across the output bus. Parallel low-cut - there is a low-cut RC tone control in series with the output bus. Series high-cut - there is a high-cut RC tone control across one half of the split pickup. Series low-cut - there is a low-cut RC tone control in series with the output bus. This is four states. There are two binary switches. While this does give us 4 novel - if questionable - options, it leaves out one fairly important one: Series high-cut - there is a high-cut RC tone control across the output bus. Or, IOW, Normal P-Bass Functionality. It's not my bass, but I'm pretty sure this will be an unacceptable omission. |
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Post by sumgai on Sept 12, 2009 14:35:56 GMT -5
ash,
So make one of the two switches a 3-throw, with the center throw disabling the 4 binary states, and not coincidentally thereby restoring the putative normal functionality.
Hmmm, you've tentatively specified push-pull pots for the switching...... Is this meant for stealth reasons, or perhaps for aesthetics? Me, I'd go back and consider a "one switch does it all" approach, just for the sake being the most simple to operate while on stage. That suggests either a rotary, or more to freak out the purists, a Strat-style 5-way blade switch.
sumgai
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Post by ashcatlt on Sept 12, 2009 18:13:23 GMT -5
I'm not sure (right now) how that "3-throw" option would work, but it won't if we're just using P/Ps. That does raise the issue you mentioned: Why P/Ps. I guess I was just trying to have it look like a standard P-Bass.
He's completely re-finishing the thing, and I don't think he's got a pickguard for it. Pretty sure I've convinced him to seperate the control section from the rest of the guard. I guess there's no good reason he couldn't just add a switch in there while he's at it. A 4P5T or similar would make this whole thing a lot easier!
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Post by ChrisK on Sept 12, 2009 19:25:19 GMT -5
Red Rhodes (Peavey) Tone_Coil Split PotCCW is the normal high-cut function across the entire pickup. CW (above aboot "7") is the high-cut shunting function (use two caps). You know, like switching the shunting cap to the center tap when in intra-pickup series. The tone pot has two functions when in intra-pickup series, and one when in intra-pickup parallel. These, along with the high-cut/low-cut switching gives 5ive functions. 2 ^2.3219280948873623478703194294894 = 5iveHoly fractalized dimensions Batman! Julia sets rule!
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Post by ashcatlt on Sept 12, 2009 21:03:06 GMT -5
ChrisK - I guess that's the part I'm missing. I'll think about it after my blood-alcohol level drops, but if you get a chance to make it blatantly obvious for me in the meantime...
Did you know that it is impossible to measure a coastline? Turns out (thanks to fractalization) that they are all infinitely long. Or at least very close to it.
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Post by ChrisK on Sept 12, 2009 21:52:31 GMT -5
Nah, that'd be like cheating or something. "Denken Sie es durch." No, it's possible, it just depends on how resolute one is. There's a new drug being tested by the FDA; it portends to extend human life into hundreds of years, but will take forever to test. Fractals are a mathematical means of generating and representing such objects. If an island had an infinite length perimeter, one might presume that it also had infinite area. There are fractal generators that generate 3D objects with infinite surface area but zero volume. There are other generators that generate objects with zero surface area but infinite volume (oh wait, that's a black hole). These will demagnetize your pickups. Just don't get too close. Schwarzschild radius Karl Schwarzschild |
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Post by ChrisK on Sept 12, 2009 22:35:58 GMT -5
tedfixxOh all right. Here's the cap shunting and series/parallel wobbulator. You get to figure out the tone control high-cut/low-cut switching. You could just rework this. 
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Post by ashcatlt on Sept 13, 2009 0:06:50 GMT -5
It's certainly possible to have an infitely long (linearly speaking) circumference with a finite area. Becomes quite difficult to calculate, though. I personally would rather sit on the beach and smoke a...  But what happens when wave action moves the coast? Now we have to start counting all over again! Thanks for the pics. It's way too easy. |
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It requires a SPDT section for one pickup and a SPST section for the other.) This leaves a switching action available in the series mode. This means, with simple terminal redistribution, that something additional can be switched to signal ground, pickup hot output, or the center tap when in series.
;D 
