pots, and caps............

[strings]

hey all you electronically literate brothers, is there any simple explanantion as to why one would use different pots, and caps. are some just better made, last longer, create a different sound. do you pick some that work better with certian humbuckers, than others? i do get the p.u. thing, just not this. if i'm looking for a simple answer, where there is none, you can let me know that too! any help would be appreciated. thank you...........

[koula901]

Glad u asked the question, I'd like to know myself. Brent can chime in here.

[kbp810]

For Pot's there are three basic types:

Wirewound - low noise, but lacks a smooth taper

Carbon Comp - most common, potential for more noise, but still acceptable (especially when used for guitar pots)

Plastic Conductive - high end, very low noise and very smooth taper, usually used in high end hi-fi type stuff

 

Nearly all marketed Guitar Pots will be Carbon Comp... from there, what matters most is mechanical feel, and the taper. You want a smooth and accurate taper, which will give you better control when trying to dial in the right setting. Signs of poor taper would be barely changing volume at all 1-7, then suddenly getting really loud at 8... or getting louder, then quieter, then suddenly louder again as you turn it up.

 

For Caps... there is a lot of debate on the topic of using Paper in Oil, and I even find myself debating with myself!

The caps in a guitar are not in the signal path... they are bleeding off undesirable high frequencies to ground. The biggest change you should notice with these caps will come from the value you choose... the common three here are as follows: .047 will roll off more highs and can leave with a warmer tone; .022 (which is my favorite value) seems to be middle of the road; .015 will let higher highs through, and can leave with a brighter tone (can get brittle-too bright I think). Along those same lines, another important factor in my book is tolerance; I shoot for something in the realm of a 5% tolerance, and/or I check the cap with a meter first to see what it's true value might be. I've had .022 caps actually read closer to .015 before... so in essence that cap didn't end up sounding good (too bright), but it was more likely due to it's true value being lower then expected, and not the composition.

 

All that being said above though... I do like Paper in Oil caps, there does just seem to be some sort of hidden magical mojo hiding in them - even if though that statement is contrary to everything I just tried to explain about tone caps above

[bobmeyrick]

It's also worth mentioning that pots can be "linear" or "logarithmic". If a linear pot was used as a volume control and the full output was 1 volt, for example, turning the pot down half way would reduce the output by half to 0.5V, turning it down a quarter of the way would reduce the voltage by a quarter to 0.75V. In other words the output voltage would be proportional to the position of the control. However, our ears don't operate in that way, so turning the pot half way down wouldn't sound half as loud.

 

The ear's response is logarithmic, and if you want to open the can of mathematical worms to do with decibels, try this - http://en.wikipedia.org/wiki/Decibel. Suffice it to say that turning the logarithmic pot down half way would make the output sound half as loud. Log pots are also known as "audio" pots because of their application in volume controls in amplifiers etc. If you use a linear pot as a volume control, I think the perceived loudness falls away rapidly as you turn the control down. Hope that makes sense, and someone correct me if I've got it wrong! I'm not sure which type of pot is better for use in tone controls, and it may be a matter of individual preference.

[eljay]

All that being said above though... I do like Paper in Oil caps, there does just seem to be some sort of hidden magical mojo hiding in them - even if though that statement is contrary to everything I just tried to explain about tone caps above

 

isn't this the same phenom as tube amps "sounding better" than solid-state jobbies, even though on paper the specs are the same?

[Guest HRB853370]

Between KBP's and BobMeyrick's explanation, I think I really understand this now! (Not like I need to). Thanks guys!

[kbp810]

isn't this the same phenom as tube amps "sounding better" than solid-state jobbies, even though on paper the specs are the same?

Considering some of the great SS amps out there now... yeah sort of

 

Though they usually don't really look the same on paper though - the great tube sound comes from being artfully low-fi... that magical sounding roundness, clipping, distortion, actually comes from the tube sort of failing in a very good way. It's tough for the average SS design to artifically re-produce that behavior.

 

But then again, I'm one of those cork sniffing tube snob types, so my input on the matter may be slightly biased

[strings]

hey, thanks, very well explained, now atleast i some understanding.............. thanks

[NoNameBand]

The other thing to consider with Pots is resistance. All electronics add resistance and take away the natural sound of the pickups. Much of this resistance is at the top end of the frequency. This is why it is important to choose the right k ohm resistance in the pots. Example; a 250k ohm pot will cut off more high frequency than a 300k or 500k ohm pot. However, the difficulty comes in with the rating. Most are + or - 20%. The boutiques like RS Guitarworks and so many others, specialize in pots (or Super Pots) that have been measured and tested for their respective value. So a pot from RS Guitarworks actually has the resistance written on the back so they know exactly what they are dealing with and they will install more resistance like a 525-550k ohm on the bridge pickup and a 500-515k ohm on the neck pickup assuming Humbucking pups are being used. For single coils (Fender style), most use a pot of 250k ohm and some use 300k ohms for P-90s. Sometimes, 300k pots are used for volume controls with humbucking pups. This will Cut high end, a great trick if your pups are a little too bright.

 

I have had very good experience using CTS +or- 1% pots tested by MOJO Music in North Carolina. In a solid body mahogany guitar, I have tried a 300k ohm pot for the volume and a 500k ohm Linear taper pot for the tone along with Luxe Bumblebee tone capacitors. I find this to be a very warm and smooth set up. Great vintage sound.

I hope this helps.

[bobmeyrick]

Many years ago I bought a useful little book - "Customising Your Electric Guitar" by Adrian Legg (http://www.amazon.com/Customizing-Your-Electric-Guitar-Reference/dp/082562262X) - which has lots of ideas for different wiring options, as well as tips on general setting up of the guitar. When I was searching to see if it was still available, I came across this little gem...

[Hfan]

For Pot's there are three basic types:

Wirewound - low noise, but lacks a smooth taper

Carbon Comp - most common, potential for more noise, but still acceptable (especially when used for guitar pots)

Plastic Conductive - high end, very low noise and very smooth taper, usually used in high end hi-fi type stuff

 

Nearly all marketed Guitar Pots will be Carbon Comp... from there, what matters most is mechanical feel, and the taper. You want a smooth and accurate taper, which will give you better control when trying to dial in the right setting. Signs of poor taper would be barely changing volume at all 1-7, then suddenly getting really loud at 8... or getting louder, then quieter, then suddenly louder again as you turn it up.

 

For Caps... there is a lot of debate on the topic of using Paper in Oil, and I even find myself debating with myself!

The caps in a guitar are not in the signal path... they are bleeding off undesirable high frequencies to ground. The biggest change you should notice with these caps will come from the value you choose... the common three here are as follows: .047 will roll off more highs and can leave with a warmer tone; .022 (which is my favorite value) seems to be middle of the road; .015 will let higher highs through, and can leave with a brighter tone (can get brittle-too bright I think). Along those same lines, another important factor in my book is tolerance; I shoot for something in the realm of a 5% tolerance, and/or I check the cap with a meter first to see what it's true value might be. I've had .022 caps actually read closer to .015 before... so in essence that cap didn't end up sounding good (too bright), but it was more likely due to it's true value being lower then expected, and not the composition.

 

All that being said above though... I do like Paper in Oil caps, there does just seem to be some sort of hidden magical mojo hiding in them - even if though that statement is contrary to everything I just tried to explain about tone caps above

KPB, refresh my memory, you have to remove the caps from the circuit to test their capacitance, correct? I've got an old amp and an old guitar with some original caps. Do I really have to yank them to test them on my Fluke?

Thanks

[FredZepp]

Hey, that Adrian Legg video was pretty cool....