Question How does 500K pot change sound of Axis/ASS?

[Wahoonc]

I've never changed tone/volume pots on any of my guitars, but after switching to the Fractal AX8 a year ago I've learned a lot about using the volume/tone knob to control tone. I suspect that switching to a 500K volume pot will cover more ground between a cleaner sound on the low end to more breakup on the top end. Is this correct?

And I'm not sure how a 500K tone pot would affect the tone--has anyone done this on the Axis/ASS?

 

[beej]

What matters to your pickups is the total load they see. This includes the cable (which has capacitance), the input impedance of your amp, and your pots. Changing any of those things makes an audible difference.

With a passive guitar (i.e. no buffer on board), the biggest bang for the buck change is usually your cable. Using a low capacitance cable will allow more high end to reach the amp, so you get more highs. (If you're going for a sparkly Strat thing, that's what you want.) Likewise, using a cable with more capacitance will roll-off the top end a lot more and shift things toward the midrange. (More ideal for gainy sounds.)

For pots, you have to calculate the resistance of two pots together (1/total = 1/R1 + 1/R2). If you have two 500k pots, the pickups see 250k. Two 250k pots, the pickups see 125k. More total resistance affects the resonant peak of the circuit, giving you a larger peak in the higher end. To our ears, that seems brighter.

The Super Sport already has a 500k volume and a 500k tone pot, so 250k total. The Axis only has the one 500k pot. Bridge differences aside, the Axis will seem brighter than the Super Sport.

So- you want to brighten up the Super Sport? Try unsoldering one lug from the tone pot (effectively removing it). You want to darken the Axis? Rather than add a tone pot, you can wire a 500k resister between the outside lugs of the volume pot (it'll do the same thing). If you want to experiment for fun, run some alligator clips to the outside lugs of the volume pot and try a few different resistors.

This assumes the tone pot is all the way up (maximum resistance), where the capacitor has no effect. As you turn down the pot, the main effect is to reduce the resistance of the pot, affecting the overall resistance and darkening the signal. As you get towards halfway down, the capacitor starts to come into play.

There's obviously more to it, notably the effect of pickup inductance which determine the window of frequencies they pass. Another thing you can do is wire an inductor in parallel (Bill Lawrence sells a neat one), that you can wire up to effectively reduce the inductance of the pickups, and take out the mids.

Hope that helps.

 

[Wahoonc]

Whoa. JK. The impedance discussion makes sense. I might play around with swapping cables to see what happens. I have used the same cable for years, but have a few in the closet, including a coiled EBMM that I'm sure has more capacitance than the one I use. Will test mix and matching with the guitars.

So, one more question. Given the GC ability to actively read the load (to normalize the difference between say a 10 ft cable and a 30 ft cable), what is actually happening there. I know it's a different animal, but now I'm curious.

Thanks, Beej.

 

[beej]

Given the GC ability to actively read the load (to normalize the difference between say a 10 ft cable and a 30 ft cable), what is actually happening there. I know it's a different animal, but now I'm curious.

I've never played GC, so correct me if I'm wrong, but I thought it was active switching, passive output? So it's just like any other guitar, unless you have the piezo and use the mono (blended) output, which has a buffer.

With a buffer (and this applies to any guitar with an on-board buffer), the output impedance is low, which negates any effect from cable capacitance. Basically the guitar's electronics are isolated from what happens downstream. In that sense, it won't matter what length of cable you use.

Hope that helps.

 

[Wahoonc]

You can set the pickups to "active" distinct from the active switching. See screenshot below. It changes the output impedance to better maintain the signal for long runs.

 

[beej]

Ah- thanks for that (I've never seen it!). Very interesting. So you can set the active/passive with individual presets. That is cool.

So in active mode, you just have a low impedance output, same as with the other buffered MM instruments. Negates the effect of cable capacitance.

I've really got to pick one of these up at some point.

 

[Wahoonc]

It's great guitar. For the price you can find one for these days, one of the best bargains out there.