Shielded cavities vs shielded wire

[uOpt]

Re: Shielded cavities vs shielded wire

There is no way that you build up enough capacitance using braided shield wire inside a guitar to come remotely close to a high quality 6 meter cable to your amp.

Also, braided shield wire usually has less capacitance than more commonly used plastic wire because the distance between inside lead and shield is larger. Not that it matters.

 

[Chistopher]

Re: Shielded cavities vs shielded wire

I'm kind of okay with this noise though. It's audible in a recording and I've used it to take up sonic space in a couple clean guitar-only tracks. It's a very specific use (I've only recorded with it twice) and I'm kind of torn about fixing it, but I think I will. It's gotten kind of annoying.

 

[Darg1911]

Re: Shielded cavities vs shielded wire

There is no way that you build up enough capacitance using braided shield wire inside a guitar to come remotely close to a high quality 6 meter cable to your amp.

Also, braided shield wire usually has less capacitance than more commonly used plastic wire because the distance between inside lead and shield is larger. Not that it matters.

I agree, I personally don't sweat the capacitance of guitar wiring. That said, I have measured the capacitance of the different cables that I use for internal wiring. The vintage style braid is the highest, varying from around 80pf/foot to 100pf/foot. One would think that the fabric insulator/dielectric (probably high cotton content), which should have a very low dielectric constant, should help to lower capacitance, but for whatever reason, the cable type is still high capacitance. I'd blame my meters but seeing how they show results that are right in line with cables that state the specifications, I have to assume that the cable capacitances that I'm measuring are pretty accurate.

 

[freefrog]

Re: Shielded cavities vs shielded wire

I have measured the capacitance of the different cables that I use for internal wiring. The vintage style braid is the highest, varying from around 80pf/foot to 100pf/foot. One would think that the fabric insulator/dielectric (probably high cotton content), which should have a very low dielectric constant, should help to lower capacitance, but for whatever reason, the cable type is still high capacitance. I'd blame my meters but seeing how they show results that are right in line with cables that state the specifications, I have to assume that the cable capacitances that I'm measuring are pretty accurate.

FWIW, I've got exactly the same results than you with two kinds of lab meter. Knowing that a LP contains +/- 120cm of braided shielded cables (including those of the pickups) and that other components are capacitive too, we can expect a LP wiring harness to exhibit more than 360pf. I don't find it negligible when I think that my lowest capacitance guitar cables measure 168 pF to 180pF for 10 ft...

 

[uOpt]

Re: Shielded cavities vs shielded wire

I don't think that can be correct for the cables to the amp. Here are the values for Belden cable materials:

[code'n'paste]

belden low capacitance cable:
- 8410 Single-Conductor 25 AWG 52 Ohm High-Impedance Cable 500ft
  ==> 108 pF/m  80% shield coverage, black.  $840/500ft
  # sells at $35 shipped for 40 feet
- 9396 25 AWG, 246 pF/m,  90% shield coverage, grey
- 9394 20 awg, 180        95%                  black
- 9778 20 awg, 148        100+75%              black
- 9395 18 awg, 180        68%                  black
# this is the thin crap that I have
#- 9264 24 awg,  98      100%                  black (50 ohm cable)
other (TP):
- 8762 20 awg,  49       100%                   56 ohm impedance

That is per meter. I highly doubt that any material beats Belden 8410 by a margin.

 

[uOpt]

Re: Shielded cavities vs shielded wire

Good point about the internal wiring, though. If you have a 6 meter cable to the amp, and 1 m of internal wiring, and the internal material has 3x the capacitance per meter, then using that internal wire would add 50% to the total capacitance.

I think I'm gonna go measure some things later today. I got a new capacitance meter. As mentioned measuring capacitance is tricky, let's see what I get for various things about here.

 

[Darg1911]

Re: Shielded cavities vs shielded wire

My lowest cap guitars cables are made from Lake cable. They are around 30pf/foot. There are certainly lower cap cables available. I just don't have any. Personally, all I care about is how the guitar sounds, not how the internal wiring measures. I imagine that if I had a guitar that I thought was lacking top end and it was wired with vintage braid or other high cap cable, I would certainly entertain the thought of rewiring with a lower cap cable, or even just using wire if I could get away with it. But that hasn't happened. I've had some muddy necks but that wasn't for a lack of treble. I just dealt with one not long ago and it didn't have any coax in it at all. It was mostly solved with a pickup swap.

 

[freefrog]

Re: Shielded cavities vs shielded wire

I don't think that can be correct for the cables to the amp. Here are the values for Belden cable materials:

[code'n'paste]

belden low capacitance cable:
- 8410 Single-Conductor 25 AWG 52 Ohm High-Impedance Cable 500ft
  ==> 108 pF/m  80% shield coverage, black.  $840/500ft
  # sells at $35 shipped for 40 feet
- 9396 25 AWG, 246 pF/m,  90% shield coverage, grey
- 9394 20 awg, 180        95%                  black
- 9778 20 awg, 148        100+75%              black
- 9395 18 awg, 180        68%                  black
# this is the thin crap that I have
#- 9264 24 awg,  98      100%                  black (50 ohm cable)
other (TP):
- 8762 20 awg,  49       100%                   56 ohm impedance

That is per meter. I highly doubt that any material beats Belden 8410 by a margin.

Look there: http://www.shootoutguitarcables.com/components/sommer-spirit-llx-guitar-cable.html

The values mentioned in this page are spot on those that I've measured on my own LLX cables with our lab DMM's.

Sommer Spirit LLX and Sommer "Black Zilk" are excellent cables, that I highly recommend.

 

[Chistopher]

Re: Shielded cavities vs shielded wire

So I've recieved all these measurements for capacitance in shielded wires, does anyone have examples of the capacitance of different varieties of unshielded wires?

 

[uOpt]

Re: Shielded cavities vs shielded wire

So I've recieved all these measurements for capacitance in shielded wires, does anyone have examples of the capacitance of different varieties of unshielded wires?

That should actually not matter(tm).

(famous last words, but really, there isn't much to form a capacitor)

If you are really concerned you can put the two wires through different channels in the body

FWIW, you can easily figure out what additional capacitance does to your guitar by using a very short cable (low capacitance) and then put a variety of capacitors as load capacitors (crocodile clips or whatever, fancy people use 12-way rotary switches).

 

[Darg1911]

Re: Shielded cavities vs shielded wire

So I've recieved all these measurements for capacitance in shielded wires, does anyone have examples of the capacitance of different varieties of unshielded wires?

If you are really wanting to wire a guitar with shielded cable of the lowest capacitance, just use RG174. It's about 30pf/ft. You probably aren't going to find anything that's much lower C and still be small enough in diameter. Otherwise, just use wire and don't worry about it.

 

[Chistopher]

Re: Shielded cavities vs shielded wire

I'm sorry if I'm looking too far into this, but it's just that I've never tried it and wanted to see others opinions on the subject. I'm going to try it myself now and report back in a couple of days with my results.

 

[thanaton]

Re: Shielded cavities vs shielded wire

So I've recieved all these measurements for capacitance in shielded wires, does anyone have examples of the capacitance of different varieties of unshielded wires?

That's no possible, because if you understand that it's the shielding itself that defines the capacitance per foot, then having a cable with no shielding means that no capacitance is defined.

Having said that, unshielded wire will certainly capacitively couple with other conductive metal in the circuit, but it will do this by no certain amount, since it doesn't really have anything to do with the wire specifically. Thicker wire means more conductive surface, which means more capacitive coupling. To reduce it you would want to use the thinnest wire you can get away with. On the other hand, thin wire breaks more easily, so there is give and get.

 

[Clint 55]

Re: Shielded cavities vs shielded wire

Things that I've tried that seem to help lower noise are getting a ground wire soldered to the bridge. Also solder a ground wire to a screw mounted in the body. Having a ground wire connected to the shield tape also helps, but the down side to that is it will kill your signal if your pickguard isn't super tidy and a hot wire makes contact with the shielding. It helps to have each electronic part grounded by a wire as well which people don't do for some reason. Run ground wires to the blade and mini toggles.

 

[uOpt]

Re: Shielded cavities vs shielded wire

Using unshielded wire between pickups and cavity will usually get you unacceptable amounts of noise.

An exception might be a guitar with a pickguard that has a shield on the underside of the pickguard (which is then grounded via your body), such as a Stratocaster. You can also twist the wires to cut down a bit on the noise. Personally I wrap aluminium foil around the wires in a Strat, between the pickups.

In a LP or Explorer unshielded wires should generally not be practical. Especially when the pickup selector switch requires going back and forth through the entire guitar such as in a LP.

 

[uOpt]

Re: Shielded cavities vs shielded wire

Things that I've tried that seem to help lower noise are getting a ground wire soldered to the bridge. Also solder a ground wire to a screw mounted in the body. Having a ground wire connected to the shield tape also helps, but the down side to that is it will kill your signal if your pickguard isn't super tidy and a hot wire makes contact with the shielding. It helps to have each electronic part grounded by a wire as well which people don't do for some reason. Run ground wires to the blade and mini toggles.

What is happening there is simply that your belly is used as a shield by grounding your body. It is a cheap shield, and it is low capacitance, overall however it is a mis-invention. Potentially dangerous, too.

 

[thanaton]

Re: Shielded cavities vs shielded wire

What is happening there is simply that your belly is used as a shield by grounding your body. It is a cheap shield, and it is low capacitance, overall however it is a mis-invention. Potentially dangerous, too.

It's interesting that the noise drops when you touch the strings, even if your body is not directly in between the source of noise and the guitar.