What a difference a cap makes

[misterwhizzy]

So I’ve been working on each of my guitars recently trying to resolve what minor dislikes I have with each one individually. Today was LP neck pickup day. It’s never been bright enough, even with 500k pots and a humbucker wired in parallel.

I thought it had a .047 or .022 cap across the tone pot, but it was actually .010. Desperate times, right? I swapped it for a .001, and it sounds almost like a single coil clean now while still retaining clarity under gain. Most importantly, it does the edge-of-breakup with volume rolled back thing to avoid having to go full clean channel on the amp. I don’t think I have anything left to tweak on this guitar now, and that’s great.

 

[freefrog]

I'm an adept of low value caps for decades. 1nF (0.001µF) is something that I have on center position of TBX pots in various guitars (from Strat to Flying V).

A well known boutique winder also promotes a "high definition" tone pot based on a low value cap.

When the tone pot is full up or moderately lowered, counter intuitively, a 1nF cap makes a difference that a 47nF wouldn't cause compared to a 22nF or 10nF ... The 1nF alters noticeably less the response of the pickup until resonant peak (hence the impression of a brighter response expressed above).
Once the tone control frankly lowered, 1nF acts more like a mid enhancer than it filters the high range: it shifts down the resonant peak in the high mids and gives it a higher Q factor, making it more focused.... just like a long cable would do. But a small cap is less cumbersome than a long cable... ;-)

1nF in parallel with standard Strat pickups gives them the same kind of EQing than Quarter Pound single coils (without the added volume due to QP's: I'm talking only about the resonant frequency here).

A 3,3nF cap (0.0033µF) in parallel with Filter'Tron pickups is a way to make them sound a lot closer to P.A.F. clones. For a similar effect, one can also play them through 80' of cable instead if one likes spaghetti wiring on the floor...

Non limitative list but enough spaghetti rambling: enjoy with your 1nF cap, misterwhizzy!

 

[Clint 55]

1nf is hardcore. Keeps ur neck pup chirpy and only subtracts highs basically. Won't make the sound muddy at all or introduce any bassiness. 2 and 3 are also good values for that. 6.8 and 10 are low but still actually can make it bassy.

 

[Artie]

I'm curious what pup you're using. A .010 uf cap should be pretty bright. But glad you got her dialed in.

 

[misterwhizzy]

The pickup in question is a WLH neck model.

 

[Chistopher]

You replaced the tone cap and now your humbucker sounds like a single coil?

 

[misterwhizzy]

Closer to it, but without the hum. Tone descriptions are always subjective. I’m confident the surgery was performed successfully.

 

[freefrog]

Well, if the pickup was already wired (and remains) in parallel, a low value tone cap might be a last step toward the desired sound... As I said, very low value caps are paradoxical: they have the least effect when the tone control is at 0 but when the pot is full up, these very low value caps are the only ones to make the pot behave as if it had a tiny wee bit more resistance... This effect can be checked experimentally with electrically induced resonant peaks and simulated with 5spice, for the record. And it appears only under 2nF, if any...

 

[Chistopher]

I'm an adept of low value caps for decades. 1nF (0.001µF) is something that I have on center position of TBX pots in various guitars (from Strat to Flying V).

Also what do you mean by center position on a TBX?

 

[freefrog]

Also what do you mean by center position on a TBX?

A Fender TBX has 3 positions:
-full up = the 1M part @ 10/10.
-"detent" position, that I've named "center" because it's there when the knob is set @... 5/10. In this "detent" position, the 1M part of the pot is @ 0/10 and the 250k part of the pot is not yet enabled...
-full down: the 1M part remains @ 0/10 and so does now the 250k part...

I use such TBX pots for fancy wirings like:
-full up = inductive filter enabled in parallel with the pickup(s). Brightest thinnest tone.
-detent ("center") position = low value cap enabled in parallel with the pickup(s). Mid-centric voicing...
-from 4.5/10 to 0/10: 250k part used as a regular tone pot trimming the high range.

 

[Artie]

It would be interesting to see if one could measure the relationship with a certain value cap, and installing a cover. (If possible at all.) For example, you have your tone dialed in perfectly, but cosmetically, you want chrome covers. Could you reduce the cap value to compensate for what you lost with the cover? :scratchch

 

[freefrog]

Guitar geeks often seem to consider that eddy currents due to covers can be compensated by a higher pot resistance rather than by a different tone cap value...

Personally, I'm not sure that eddy currents can even be compensated because what they do to the response of a pickup doesn't seem to be only a question of EQing: according to our tests, eddy currents slower the attack and tame its amplitude. IOW, they introduce a kind of... compression - damn, I've opened a can of worms!

 

[Artie]

I've never been a proponent of Eddy currents impact in guitar pickups because of their infinitesimal magnitude. But I respect your opinion. I'm becoming a believer. I was going try 250k pots on my DD JB/Jazz set, to "soften" them up a bit. I may try covers instead. Especially since the bobbins are getting old and cracked.

 

[freefrog]

I won't sound revolutionary by saying that a problem with eddy currents, cap values, parasitic capacitance or even pot resistance is how they might be perceptible or not according to the context - music played, gear / settings used, volume involved and, of course, the player himself...

So, I don't tend to claim or think that such or such parameter systematically makes a difference: sometimes it's the case, sometimes not. But I still find fun to experiment with all kinds of tone tricks - like putting a pair of diodes in parallel with a pickup, not really to make it distort but to obtain richer harmonics from it.

I certainly see covers as a possible way to soften the sound of humbuckers (in the same way that some famous players pulled off their covers to obtain a brighter sound with a bit more attack). The thing is to use covers just "bad enough" : too thick and with too much brass, they might really alter the tone in a detrimental way (I've kept on the shelf a couple of specimen whose influence on tone was really negative).

Let us know some day if it worked for you, Artie.

 

[Artie]

Let us know some day if it worked for you, Artie.

I will. I was thinking of those "partial" cover surrounds, like someone just showed on their P-Rails. (Orpheo, I think.) I'd use them with some of those pearloid inserts. Should look cool.

 

[Chistopher]

Once the tone control frankly lowered, 1nF acts more like a mid enhancer than it filters the high range: it shifts down the resonant peak in the high mids and gives it a higher Q factor, making it more focused.... just like a long cable would do. But a small cap is less cumbersome than a long cable... ;-)

This is a very underutilized technique to make a thin bright pickup more manageable.

 

[freefrog]

This is a very underutilized technique to make a thin bright pickup more manageable.

As a "technique", it's clearly under the radar and that's why I often evoke it online - although Bill Lawrence (RIP) was talking about that way before I did...

https://www.wildepickups.com/pages/...CA9ZnZYd6NgLzYvFIssMQ2UW8WKq9Se9QhUNJAy6BMwAG

As a tonal ingredient, capacitive load on passive pickups contributes to shape the guitar tone of countless famous tunes... Consciously or not, Hank Marvin, Hendrix or SRV were all using it to their benefit, for instance.

I like to share the following link and to recall that when the guy plays through 75' of cable, it's largely as if he had added a 2.7nF to 3.3nF from hot to ground of his pickups...

https://youtu.be/u2sjeVQpS94?si=q6IJUHx4H47NkM0k&t=402