Guitar Cap Mythbuster

[randalp3000]

So last week I put some recycled Bumble Bees in a friends 59 Les Paul copy with original pots and Trobak old stock wire PAF's(he also has a real 56 and 57 to compare). He's seriously obsessive and a great player who has or had every top shelf vintage amp/guitar so he knows his stuff.

Well this got my OCD kicking in this mourning when I was trying to sleep and came up with this idea. I'm going to build this thing with terminal strips on the outside of the box so it's easy to swap out caps. So now I can see for myself if I can hear the difference between brands of the same value or cap direction. This can also come in handy for picking the best value for your guitar. I also put a bypass in so you can hear how much it colors your sound with the tone turned all the way up. Now I just have to wait for the terminal strips.

I think the next step is to build a Champ or something simple and switch between all the coupling caps.

[Cantplay]

Couldn't you tie all the caps together at one end, and just use a selector at the other?

Might want to break the caps in on a burn in rig first.

John

[Leo_Gnardo]

Our friends over at MEF have been kicking the subject around all week, some kicking harder than others. Have a look, maybe some mythbusting has already been done for you. But you can try it on if you want, knock yourself out.

http://music-electronics-forum.com/t32846/

[Blackburn]

You should've mentioned this earlier. I coulda packed a couple with the tranny and you'd be set for tomorrow. I don't use them too much, but always good to have around for that special occasion.

[randalp3000]

John, I could tie them all together but I don't want anything for someone to cry about so I am going to isolate them. Also one of the things I would like to debug is breaking in a cap. If you happen to have 2 that measure the same and one is broken in I'd be happy to purchase them.

Leo, great thread, thanks. It got a bit long winded with the bumble bee debate but it confirmed my thoughts on caps so far. The argument that with a tone control on ten(500k pot) the cap wont affect the sound I feel is BS. There is a significant difference on an Esquire between having the tone control in or out of the circuit.

Personally I feel that if the caps measure the same they should sound the same in a guitar. I am curious to see if polarity will make any difference. Also it should be fun to have some of my friends do a blind test.

Here's another can o worms. My pedal board all true bypassed not only rolls off highs it also boosts mid-range. And Lava ELC cable compared to George L with the same capacitance for a specific length still sounds different. Tests were done using a bypass-able loop box.

[jjman]

This is a tone cap that grounds out some frequencies. I would want to see frequency response graphs. Any verbal statements of tone or mojo would not influence me considering one hears none of the signal that goes thru the cap (to ground.)

[martin manning]

This is a tone cap that grounds out some frequencies. I would want to see frequency response graphs. Any verbal statements of tone or mojo would not influence me considering one hears none of the signal that goes thru the cap (to ground.)

But you do hear what's left, right? So, if different caps sound different when the signal is passed through them, I would expect them to sound different in this application too.

[Leo_Gnardo]

Leo, great thread, thanks. It got a bit long winded with the bumble bee debate but it confirmed my thoughts on caps so far. The argument that with a tone control on ten(500k pot) the cap wont affect the sound I feel is BS. There is a significant difference on an Esquire between having the tone control in or out of the circuit.

Yes, long-winded, & a couple of side topics of more or less interest. About halfway through the OP comes to the conclusion it would be more instructive to experiment with different value caps rather than try same-value caps of different manufacture & vintage.

At one time I thought the tone cap would make no difference with the control full up but careful listening showed me that's not so. (Currently there are "special" pots available that do go open-circuit when dialed full up, so there's an option that does take the cap out of circuit.) With a guitar that has bright sounding pickups, and an amp that brings them through, a small but audible high end rolloff can be heard. Got to listen in a quiet room with no distractions, also have enough hearing acuity at those high frequencies too. Your results may differ, but if you hear a difference, it's there.

Personally I feel that if the caps measure the same they should sound the same in a guitar. I am curious to see if polarity will make any difference. Also it should be fun to have some of my friends do a blind test.

Possibly a tiny bit less hum if the outer foil is connected to ground in a tone circuit. Shouldn't be much else. And make sure the blindfold is over the eyes, and not also over the ears. Done that too - kinda muffles things.

[Here's another can o worms. My pedal board all true bypassed not only rolls off highs it also boosts mid-range. And Lava ELC cable compared to George L with the same capacitance for a specific length still sounds different. Tests were done using a bypass-able loop box.[/quote]

Interesting! unless there's a LOT of cable I wouldn't expect much of a difference. Wouldn't expect a boost either unless there is some device that claims to be true bp but isn't. Got a wah pedal in there? The old fashioned style Thomas/Vox/Dunlop wahs are famous for eating high frequencies whether in or out of circuit. I put DPDT push buttons in them for true bypass. Overall you could try the usual band-aid, put a MXR Micro-Amp or similar buffer first in the pedal chain, at least try one & see if it helps send full range signal thru.

[Cliff Schecht]

This has me curious enough to try to get my 8903B running to try to take some frequency plots. It's got an incredibly accurate signal source and is fully GPIB programmable. Also this would give me something relatively productive to do in all of the free time I currently have .

[Cantplay]

What cap value do you need?

I can contribute caps for research if I have.

I'm already guessing that capacitance alone isn't the sole factor in tone, ESR probably also plays some part. Caps are also microphonic to different degrees.

You might see something different with waterfall freq plots vs standard.

John

[Leo_Gnardo]

Caps are also microphonic to different degrees.

You might see something different with waterfall freq plots vs standard.

John

Microphonic definitely - old disc caps for sure & OD's sound "clacky" to me. When tested with a steady-state signal, all caps R the same. Try testing with a pulse & waterfall graph, may reveal something about what we really hear. And caps especially in combo amp are being shaken around. Microphonic ones will lend something to the tone for better or mostly worse.

[vibratoking]

The mids can be boosted in certain configurations. The RLC circuit comprised of your pickup, pots, cables, and amp input can result in resonant frequencies.

I've done some sims, but I don't have access to the results from work. Also, Terry Downs had a white paper with sim results on the net somewhere. Although, I think he may have removed them. Not surprising at all that you could get a mid range boost.

[pdf64]

My view is that for something to be significant, the drummer would have to make an unsolicited comment on the change.
Or even better, an audience member.
Pete

[vibratoking]

Funny, I don't hold general audience member's or drummer's opinions in high regard. My drummer always has earplugs in so I know he can't hear anything useful. I will only seriously entertain feedback from people that I have a past history of listening and critiquing sound with. Anything else is just talk IMO. "Oh it sounds sooooo good!" Then she bats her eyes. "I really feel tuned into the music that you are playing." Big smiles. "My friends left me and I need a ride home tonight." Followed by awkward silence...

[Leo_Gnardo]

"Oh it sounds sooooo good!" Then she bats her eyes. "I really feel tuned into the music that you are playing." Big smiles. "My friends left me and I need a ride home tonight." Followed by awkward silence...

sounds like a positive review to me! If she buys your CD's besides, extra points!