tone shaping my JB
- Thread starter Supernautilus
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Supernautilus
New member
Yeah, THIS is exactly how I thought it worked. But now I’m confused lol.
freefrog
Well-known member
Clint, you're right: a tone pot cuts highs above the frequency set by the cap + the inductance of the pickup, shifting the resonant peak towards a new and lower pitched resonant frequency.
BUT it does that only when set under 3.5/10 approximatively (albeit it depends on the taper of the pot, of course: i mention this value as simply "typical"). From 10/10 to 3.5/10, the action of the tone pot is mostly RESISTIVE and mostly flattens the resonant peak, exactly like a lower resistance of pots would do.
There are "nuances" due to components: at 6/10, a tone control won't affect the HARMONICS exactly in the same way according to the component paired to it : the sound will be slightly different with a 22nF cap, or a 100nF, or a 47nF, or a Q filter... but the resonant peak itself will NOT be affected by the cap when the pot is @ 6/10: only the RESISTIVE LOAD of the circuit will shape the resonance in such a case.
Here is a link about that, among dozens of topics explaining the same thing than me on the Web:
https://nextgenguitars.ca/pages/whats-new.htmla-different-kind-of-tone-control/
Hope my previous statements are clear now. Thx for reading.
Last edited:
freefrog
Well-known member
Don't be confused, I've clarified my previous statements in post 24.
FWIW: I test guitar electronics with lab gear for decades. Earning my life by teaching in a school for future engineers has been helpful.
I've also worked episodically with and for several pickups winders (not blowing my own horn: it's just to constextualize my statements). Now, believe what you want, do what you want and be happy.
Supernautilus
New member
Don't be confused, I've clarified my previous statements in post 24.
FWIW: I test guitar electronics with lab gear for decades. Earning my life by teaching in a school for future engineers has been helpful.
Now, believe what you want, do what you want and be happy.
Thanks for the additional info. I don't really understand it all though lol. But no worries. I'll just try the no-load 500K and see what happens. I also ordered a 1 meg pot too just to see how it would work for the tone pot. I'll report back after I try a few things.
Supernautilus
New member
Don't be confused, I've clarified my previous statements in post 24.
FWIW: I test guitar electronics with lab gear for decades. Earning my life by teaching in a school for future engineers has been helpful.
Now, believe what you want, do what you want and be happy.
I like the sound of that ""resonant peak amplitude adjuster" tone control mod though. That sounds really useful actually. I might try that in fact. Thanks again for the tip.
freefrog
Well-known member
The link in post 24 has been shared mostly for its comment about how a tone pot works : "Notice for the first few notches down, it is really only affecting the resonant peak of the pickup". The graphs were another reason to refer to this page, since they clearly show how a resonance squashed by the first positions of a tone pot is close to a rounded peak due to lower resistance pots...
But the "alternative" idea of this article (mounting a resistor instead of the usual tone cap) is also based on the fact that a tone pot is mainly resistive during a good part of its curve... The capacitor of a normal tone control can rapidly affect the harmonics in a subtle way but it REALLY enters in the game in the last positions only and dictates its resonance to the pickup even later: the resistance of a tone pot must be reduced to 23k or less than this before to let the cap really doing its own revoicing job.
Reason why, on guitarnutz2, "ms" (Mike Sulzer) has posted a schematic with 10k resistors instead of tone caps:
https://postlmg.cc/PPwgwgyh
But he has also put in this schematic a pair of switchable low value capacitors: 1200pF, 1500pF. These components from hot to ground mimic the parasitic capacitance of 10 to 15 meters of added guitar cable... They don't shift the resonance of pickups in the bass or low mids, like a normal 22nF/47nF/100nF tone cap would do: with their lower value of 1.2nF or 1.5nF, they just relocate the resonance in the high mids.
Conversely and as explained in my first answer above, using a cable with a very low capacitance would shift UP the peak and make the pickup brighter... with more snap and bite. ;-)
More later if needed, including some real life measurements of resonant peaks altered in their amplitude and Q factor by tone pots and/or lower pot resistance... :-D
freefrog
Well-known member
Hey, what about real resonant peaks really measured on a real pickup? ;-)
See below. Average humbucker whose response has been electrically induced, through 10' of average cable in a 1M input. Linear scale. Vertical steps of 1dB to make things obvious.
Black line= resonant peak with a 500k volume (full up) and a no-load tone pot.
Pink line = same thing but the no-load pot is now a 250k tone control (full up).
Red line= 250k volume and 250k tone control, both full up.
Green line = 500k volume and 500k tone control LOWERED (not full up).
I had to "offset" a bit the settings to avoid the red and green lines to stack exactly in a single brown line... the pic wouldn't make sense if it was the case.
Conclusion (that I hope to be useful): when it comes to resonant peaks, two 250k pots full up give the same amplitude and Q factor than a 500k volume full up + a 500k tone control lowered (to 166k approximatively)...
FWIW: shared for the pleasure to share, if not to help.
See below. Average humbucker whose response has been electrically induced, through 10' of average cable in a 1M input. Linear scale. Vertical steps of 1dB to make things obvious.
Black line= resonant peak with a 500k volume (full up) and a no-load tone pot.
Pink line = same thing but the no-load pot is now a 250k tone control (full up).
Red line= 250k volume and 250k tone control, both full up.
Green line = 500k volume and 500k tone control LOWERED (not full up).
I had to "offset" a bit the settings to avoid the red and green lines to stack exactly in a single brown line... the pic wouldn't make sense if it was the case.
Conclusion (that I hope to be useful): when it comes to resonant peaks, two 250k pots full up give the same amplitude and Q factor than a 500k volume full up + a 500k tone control lowered (to 166k approximatively)...
FWIW: shared for the pleasure to share, if not to help.
Clint 55
OH THE DOUBLE THICK GLAZE!
freefrog you are out-of-control.
1 meg doesn't work well for tone pots because you have to turn them down to 2 for them to take effect. I always recommend 250k no load pots as tones because the whole sweep is usable - max bright on 10, start to hear darkening as soon as you cock it back to 9. Some guys like the coloring of the upper sweep of 500k tones but I don't really find use for that. A 500k tone still has to be turned down a lot to get darkening, and you'll absolutely want to use audio taper if you do. If you want a longer sweep of a tone, then use a 300k pot.
Artie
Peaveyologist
Another cool link from freefrog. Thanks.
Supernautilus
New member
I see, makes sense.
Thing is though, I don’t really use pots to be honest. I always run everything on 10. Except when using split or paralleled coil switching. Then I turn down the tone pot a little to combat the extra brightness.
But other than that I don’t really touch them. So for me, pots are really just fixed resistors. Which I why I like to get the values customized to sound best on 10.
Supernautilus
New member
Artie
Peaveyologist
This is another thing you can do that's only a little bit of work. (Worth it, IMHO, to get your tone right.) Just wire a 1 Meg pot as I show here, in place of the volume. Start with it all the way up. Then just play with the setting 'til you get just the tonal character that you like. Then, being careful not to move the knob, cut the "hot wire" from the pot, and measure the resistance to ground. That will be your ideal volume pot. (You'll have to settle for close, using standard pot values.
Then, if you want, do the same with the tone pot, but install the cap between that left-hand lug and ground. Rinse & repeat. It's something I do, occasionally.
Then, if you want, do the same with the tone pot, but install the cap between that left-hand lug and ground. Rinse & repeat. It's something I do, occasionally.
freefrog
Well-known member
Clint, "that's incorrect".
LOL. ;-)
Supernautilus : +1 on this last super idea from Artie!
I was about to post something in the same vein albeit less refined: resistors from hot to ground are an easy way to adjust the overall resistive load... Bill Lawrence was using this trick with always the same kind of 500k pots in order to save money so it doesn't appear to be a bad advice. And even if advisors are not the payers, resistors are not expensive.
If you want to "fine-tune" your pots, here is also a potentially useful link involving unexpensive resistors:
http://www.geofex.com/article_folders/potsecrets/potscret.htm
Stratocaster70
New member
I d stick to the 250K, the best I ve ever found with JB, and work the amp/pedal tone shaping/distortion
Stratocaster70
New member
I d stick to the 250K, the best I ve ever found with JB, and work the amp/pedal tone shaping/distortion
