Cap sharing?

[LushTone]

Hi there,
Hoping to consult the wiring Gurus on how to share a single .047uf tone cap (oil-paper) between the tone pots in a similar situation as attached, but with a push/pull split for the bridge humbucker only. The neck pickup will actually be a Fralin Twangmaster (2 conductor, strat sound but humbucking), and a SD Trembucker for the bridge. I appreciate the help!

 

[LushTone]

Here's an cap being shared between tones, but seems to contradict my first diagram as far a pot input/output. :icon_scratch:

 

[stratamania]

The apparent contradiction is due to different types of switches and the wiring approach being employed.

Also one is for an HH set up with a Tele style switch and the other for an SSS with a standard 5 way.

Could you clarify in addition to the two pickups what type of switch and controls you plan to use?

Looks like Vol, tone, tone but the type of switch is not clear or what each position of the switch is planned to do. If it is the same as the first diagram then why not just use an extra cap?

 

[LushTone]

Yeah, it's virtually the same as the first diagram, but a push/pull coil split for the Bridge pickup/tone. The neck 'humbucker' is a 2 conductor Twangmaster instead. I was thinking I'd share the cap if the results would be the same, because the push/pull makes a .047 oil paper cap a tight fit. But it's probably possible to use two caps. If one cap will produce the proper tone range for both pickups, I'd prefer that route. I'm not sure at this point.. :help:

 

[stratamania]

I think off the top of my head if you tried to share the cap between the two tones for the first diagram you would lose the independence between the tone controls.

Options would be to get the correct value caps of a physical size that will fit.  PIO caps may be beneficial in higher voltage circuits but the tone benefits in a guitar may be less so. Others can debate it.

Another option might be to get rid of the push-pull and use a five-way super switch which then would give the possibilities of sharing a cap in a similar manner to the Strat diagram, and the five-way could then be used to achieve the coil split and give you extra possibilities.

On balance, if the first circuit gives you what you want I would look for smaller caps that fit. It's unlikely in a blind test that the PIO will be noticeable. (They do look cool but then you can't see them generally in any case)

 

[Cagey]

All true.

Using something other than a PIO cap would probably make life easier, as they're generally pretty large. PIO (paper in oil) is simply a dielectric material used in some capacitor designs to increase their working voltage. Different dialectric materials are used for that and/or to allow for different physical size/configuration. The capacitance of a given component can (and usually will) also change depending on that material and it's thickness, but is whatever the device is designed to have. That means if a cap is designed to have .022 µF of capacity, it doesn't matter how it's constructed or if its dielectric is air, mylar, polyester, polyamide, polypropylene, tantalum, ceramic, paper in oil, etc. It's still .022 µF.

Caps don't have a "sound" or "tone", no matter what the kids at the local Guitars 'R' Us will tell you. Apparently, the thinking is "higher cost = better performance", but that's simply not true in this application. Some are simply more or less expensive due to the materials and packaging involved, with PIO parts being at the top end of the scale due to the oil-tight packaging requirement. But, oil is a good dielectric, which is why you may have noticed that ducks never get hit by lightning and can sit on power lines without injury. Due to their OIF (Oil In Feather) construction, ducks are non-conductive, except at very high voltages. They also taste good and are high in protein.

Be that as it may, the behavior of a cap in a guitar circuit is 100% dependent on capacitive reactance, end of story. Has nothing to do with working voltage. So, if anyone claims to have heard a difference between two different caps, what they heard was a difference in capacitance. Caps are notoriously sloppy devices, with tolerances that can range as wide as 20%. That means a .022µF part can range from .018µF to .026µF, which is certainly audible in a high-pass filter.

Long story short, use those little ceramic caps in guitar circuits. They're small and inexpensive and work as well in that application as the most expensive PIO part you can buy.

 

[LushTone]

I appreciate the argument that all sorts of tones are usable sounds. That either way it will sound like a guitar. Also, that your real tone comes from your hands. BUT I can definitely tell the difference between these pio caps versus the orange drops I had in before.The black candy ones (allparts) aren't too expensive.  I think the orange drops have a more nasally wah quality. Which is cool, but my alder body guitar already has all the midrange I desire without the option. I feel like the materials used pretty much always affect the nature of things... I am one of those nerdy guys at the guitar store, but it's a brick and mortar store! So there, :laughing7: but I'm not the electronics guru like my coworker  or you guys are. I bother him with questions too much as it is. This form is so helpful!

I'll probably be stuck using an orange drop though. Or I could just use the .022 instead (smaller). The .047 seems to have more bass maintained when rolled off though...it might fit...

 

[stratamania]

The difference could well be due to the differences of values of the caps, rather than the type of cap. You could also take two caps of the same type and apparent value and they may sound different as their values could have a fair bit of difference.

The important thing is to find something that works and sounds good to you whatever the caps are made of.