So, there is this HH guitar, with a toggle switch and only two pots: volume and tone. New humbucker pickups will go in, ~7.5kΩ in the neck, ~8.5k
Ω in the bridge. I don't know caps and pots inside, but they might go anyway. I have two questions, if someone can answer (no names mentioned... @ICBM)
1. Values for pots and cap
Humbuckers are usually recommended to have 500kΩ pots for both volume and tone, and 0.022µF caps for tone. In the case of only 1 volume and 1 tone with one toggle switch, the same capacitor value will apply irrespective if there is one humbucker connected, or both humbuckers in parallel. The same applies to the pots values. In the case of both pickups active, the output impedance of the pickups together will be half that of a single pickup. Therefore, would not it be more appropriate to concoct somehow a circuit that switches to 250k
Ω pots when the switch is in the middle position, and the cap switched to 0.047µF? Has anyone tried that? Have you found this to be an issue? Any blue-sky experiences or ideas?
2. Pot taper
I did some calculations and it seems that a logarithmic taper is the best choice for both volume and tone pots. I also remember finding a while ago that the so-called audio taper is in fact close to a logarithmic taper, but with a more acute angle, more like two regions of linearity. The taper graphs that I found for a few pots manufacturers were all slightly different, but the same general shape. Do you know which taper is the most appropriate in perception—i.e. linearly perceived volume and cut-off frequency—in the real world? The taper of which pot companies you prefer, and for which types of pickups?
Comments
This is because I use the volume control as a gain control for a timmy that's always on and somewhat cranked so I can switch from polite and twangy to driven using the volume.
I like the 50s wiring because I like the options it provides more than the individual effect on tone.
I also use an EQ pedal a lot
Personally I can't see the point and I would just use standard 500Ks and a .022uF cap, or possibly a 250K volume since those pickups are not overly hot anyway so all the positions will be fairly bright - and especially if it's a Fender-type guitar rather than a Gibson-type one. Almost all factory-made guitars with two humbuckers and VT wiring (eg PRS) simply use 500Ks and .022uF.
I prefer linear or audio taper for volume - linear is better as a true volume control for clean sounds or only-just-breaking up overdrive, audio is better for cleaning up a more heavily overdriven sound. (Audio is mostly 30% taper nowadays.) Tone controls should be audio or if possible a true (10%) Log - unless you want all the range right at the bottom of the turn, for hand-wah effects and don't use the tone control normally.
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
Or maybe it is worth bothering? Is the difference so subtle as to not be noticed unless listened for?
This is the golden information I was after, and @ICBM delivered. Excellent and many thanks!
Alpha Pots:
Bourns Pots:
CTS Pots:
For the Tone pot I will go for a logarithmic pot, as I want to be able to control the corner frequency better, and it confirms my calculations as the best option for that. I happen to have a Bourns pot with the taper A2 above, which seems to fit the bill.
For the Volume, @ICBM, which of the tapers above would provide a better middle ground for achieving both good control of cleans and of overdriven? Or just go linear?
Bourns seems out of the question, as the only other option from the two audio tapers is a pure linear.
Of the CTS and Alpha, it is interesting that the tapers are quite different, in that on the Alpha there seems to be linearity in the last third of the turn, whereas the CTS pots seems to have the linearity in the first half of the turn. Any thoughts? Even if it is purely theoretical, as the actual real tapers may differ from one pot to the next, just as the resistance values.
In terms of using the three pots, I found that the Bourns pots have the best perceived quality, smooth and precise, while not stiff, then the CTSs, that were moving a bit more loosely, and then the Alphas, that felt very cheap. Would that be the general consensus as well?
Pay close attention to the pickup manufacturers' installation recommendations.
DiMarzio Tech Talk recommendations may come as a surprise. Several of their replacement pickups for Stratocaster and Telecaster are intended to be run through 500k pots.
Conversely, I have found that running some Duncan rails and/or li'l 'bucker pickups through any pots other than 250k ruins their tone.
https://www.axecaster.co.uk/index.php?main_page=product_info&cPath=11&products_id=593
Model number is EP-5586, but I couldn't find anywhere the taper of it, i.e. 10%, 20%, 30%? I couldn't find on CTS's website any information about such part numbers.
https://www.ctscorp.com/wp-content/uploads/Series-18VRG-Data-Sheet-Rev-A.pdf
If I check the the part number decoder there against the pot available at the link in the previous message, based on the description there, and it is not clear as to which taper is that pot actually.
https://www.thefretboard.co.uk/discussion/214765/new-pots#latest
http://www.thefretboard.co.uk/discussion/89942/caspercaster#latest
I love the feel of Bourns pots, but they do not do audio taper apart from 10% and 15%—and the latter do not seem to be available on the sites above. CTS and Alpha do do more tapers, as per the plots earlier in this thread, but, as you said, the names tend to say very little about their taper.