.01 capacitor

[cjj]

Do I have the wiring diagram correct? Looking at that photo it looks like the capacitor (0.01) and the resistor are wiring into the same wire, not two separate wires like I drew out.

Well, I'm not sure, exactly what you are talking about, but your drawing (corrected one) does match what the schematic shows. Looking at the photo, it is pretty hard to tell, but they may have connected the lead from the 0.01uF cap directly to the lead on the resistor and then run that one wire to the switch. That will do the same thing as running them separately to the switch. I think your answer to the question you have on your picture, about soldering both leads to the same switch lug, is yes, hook them to the same lug.

[cassius987]

...but they may have connected the lead from the 0.01uF cap directly to the lead on the resistor and then run that one wire to the switch. That will do the same thing as running them separately to the switch.

That's exactly what I was asking... but I'm really confused about how that wiring would work the same way, if the cap wasn't in contact with one of the pot lugs. Oh well. If I did this wiring I'd probably do it the "traditional" way of my corrected drawing.

Thank you all (again).

[cjj]

...but they may have connected the lead from the 0.01uF cap directly to the lead on the resistor and then run that one wire to the switch. That will do the same thing as running them separately to the switch.

That's exactly what I was asking... but I'm really confused about how that wiring would work the same way, if the cap wasn't in contact with one of the pot lugs. Oh well. If I did this wiring I'd probably do it the "traditional" way of my corrected drawing.

Thank you all (again).

OK, whether the wires from the cap and resistor each run separately to the switch lug, or the cap goes to the resistor and then to the switch doesn't matter. Here's what I'm talking about (just in case I'm not getting what you're saying):

Where the resistor and cap get connected together, whether at the switch lug or somewhere else along the way doesn't matter since a wire is a wire (well, it does start to matter when you get up to several hundred MHz, but not at audio frequencies).

[cassius987]

Well if it's kosher to wire the cap lead to the resistor lead (as you said) I may just do that... seems like it saves wire.

I haven't been able to use that program yet because I haven't had access to a PC. I am on a Mac 99% of the time. Are there any programs like it for OS X?

[cjj]

Yeah, it should be fine to wire it to the resistor lead. At these frequencies, a couple of extra feet of wire really doesn't make any difference, an inch or so won't matter at all.

As for a program that runs on OS X, I don't know of any. It's possible Linear has a version for Mac too, I've never looked. You can probably search the linear.com site for "Mac" or something and if they have it, it should show up. The simulator from them is called LTspice, the old name was SWcad. Those stand for Linear Technology Spice, and Switcher CAD, which was what they called it when it was intended mod for Computer Aided Design (CAD) of Switching Power Supplies.

Other than that, I'm sure there is a "spice" simulator out there somewhere for Mac. Spice is a pretty generic circuit simulator that's been around for a long time (heck, I used it in college back in the 70's). With modern computing platforms, the main new thing is nice GUI's on top of the same old simulator.

[jps]

Peruse this site for OS X possible programs.

[cassius987]

I got MacSpice, and when I have some time I will learn to actually use it! I have done some demos successfully and it's a neat program for sure.

One thing I'm still puzzling over is the hierarchy of the 0.01 uf cap and the 10 M resistor... if the signal hits the resistor before the cap, isn't it a lo-pass filter? Shouldn't it hit the cap and then the resistor (if you were wiring the cap to a lead of the resistor, you'd wire it to the the one closer to the pot and farther from the switch lug).

Thanks again!

[johnallg]

Josh, the 10M resistor and the .01uF cap are forming a variable pass filter, variable because the .01uF will get more resistance in series with it as the pot is turned, which will attenuate the signal the cap passes and also change the frequency of the filter itself.

VERY simply, the 10M "bleeds" some of the raw pickup signal (full frequency) to the switch to go on out of the bass, and the .01uF filters (based on the 10M and amount of the pot in-circuit at the time) out some lows and also passes them on to leave the bass. But they all work together and interact to produce the tone shaping.

[cassius987]

Josh, the 10M resistor and the .01uF cap are forming a variable pass filter, variable because the .01uF will get more resistance in series with it as the pot is turned, which will attenuate the signal the cap passes and also change the frequency of the filter itself.

VERY simply, the 10M "bleeds" some of the raw pickup signal (full frequency) to the switch to go on out of the bass, and the .01uF filters (based on the 10M and amount of the pot in-circuit at the time) out some lows and also passes them on to leave the bass. But they all work together and interact to produce the tone shaping.

So it doesn't matter which lead the signal from the central lug hits first--the cap or the resistor? That's what concerns me.

I may go ahead and try to emulate this circuit in my Jazz Bass, and if I like what it does, I'll try it for my 4003FL.

[johnallg]

Electricity flows at the speed of light, so it really doesn't matter. Always think of parts tied together as being at the same potential and getting the signal at the same time. You only need to worry about propagation delays with very high frequency circuits and on the starship Enterprise.

[cassius987]

I did this for my Jazz Bass and it's pretty groovy! I think I need to run it through a frequency analyzer for each position because my ears aren't that sensitive, but obviously there is a huge difference from the original tone control on the Jazz. The full-on is incredibly clunky and aggressive. I mean, it REALLY sounds like a chainsaw. Full-off is very dark and thumpy. The difference from one end to the other is huge.

However, I don't know if I'll do it for my 4003FL. It sounds so good already... I don't want to mess with perfection. I have been playing some coffeehouse gigs lately and it's sooo perfect for fusion-y jazz sets as well as URB style. Dunno... but I'll let you all know if I decide to proceed.