Ran into a small issue with short-shaft pots

[vikingred]

Ok, so here is my build thread:  http://unofficialwarmoth.com/index.php?topic=25545.0

Never really thought about it but regular strat short-shaft CTS 250k pots DONT FIT all the way up through the back cavity to the top of the body.  Ugh.  And worse, I don't have any long-shaft Les-Paul type pots on hand.

Here is the body:

I've already thoroughly copper-shielded the back cavity.  Would it be insane to try to drill a countersink, or use an exacto to carefully cut out a hole on the inside of the cavity the size of the entire short shaft pot body so it would fit through to the top?  :binkybaby:  I think I could pull it off but it would certainly be a pain.  I figure I need a little more than an 1/8" to make it work and get that nut on the threads.  Danger is that if I drilled or cut through or even got too close it could be a disaster. 

It's only 2 pots for this build, 1 master tone, 1 master volume.

I've looked around and alternatively I'd suppose I'd have to order a long-shaft Les-Paul type pot, it's like 3/4" but I don't like them, and they're not the dimple-back old-school CTS mojo impedence-matched pots that I have.

I really wanted to finish this build this weekend.  What would Jimmy Page do?  What would Cagey do? 

What say?  :sad:

 

[line6man]

Buy the right pots for the body.

What are "impedance matched pots?" The resistance of a volume and tone control need not match, and if the actual value strays from the rating, due to a poor tolerance, then the effect will only be very subtle, if audible at all.

 

[vikingred]

Buy the right pots for the body.

What are "impedance matched pots?" The resistance of a volume and tone control need not match, and if the actual value strays from the rating, due to a poor tolerance, then the effect will only be very subtle, if audible at all.

Yeah I figured that would be the answer.  Check here on impedance matching: https://en.wikipedia.org/wiki/Impedance_matching

You can get CTS pots that are tighter/matching impedances.  It's one of those things that's probably more a personal preference (subtle as it may be) but why not go for it.  The ones I have are .05% matched genuine CTS 450G Low Torque 250K split shaft audio taper volume and tone control pots.  I like them.

So I guess I get to order some 3/4" Les Paul 250k pots.  Wow.

 

[stratamania]

Jimmy Page, would probably send it out to have the work done.

I suggest getting the correct length pots, or asking Cagey if he has any he could supply. If it's going to him anyway.

 

[line6man]

Buy the right pots for the body.

What are "impedance matched pots?" The resistance of a volume and tone control need not match, and if the actual value strays from the rating, due to a poor tolerance, then the effect will only be very subtle, if audible at all.

Yeah I figured that would be the answer.  Check here on impedance matching: https://en.wikipedia.org/wiki/Impedance_matching

You can get CTS pots that are tighter/matching impedances.  It's one of those things that's probably more a personal preference (subtle as it may be) but why not go for it.  The ones I have are .05% matched genuine CTS 450G Low Torque 250K split shaft audio taper volume and tone control pots.  I like them.

So I guess I get to order some 3/4" Les Paul 250k pots.  Wow.

You are mis-educating yourself. The link you posted is not applicable to this situation. Learn more about how these circuits work before trying to blindly follow academic literature.

Using 250k pots is not impedance matching. There are all sorts of different pickups out there, with vastly different impedances. Everyone uses either 250k or 500k pots with them, however, because the industry (or Leo Fender) decided that was the standard. If you really wanted to impedance match, you would wind up with some oddball value. But what you would gain from doing it would be questionable to begin with. The main thing that happens when you change the resistance of the volume pot is that the resonant frequency of the circuit shifts up and down, and the main thing that happens when you change the resistance of the tone pot is that a little more or less treble is cut. You are arbitrarily deciding what behavior is "right" for the circuit, and you are doing so in a circuit that can tolerate fairly large changes in resistance that won't be discerned by the ear. Try experimenting with changes in resistance, and you will find that the effect on the resonant response of the circuit, as well as the effect on the taper of the sweep, will only change in a very subtle way. Even making fairly large jumps, like going from 250k to 500k, only makes a subtle difference. If you are going to nit pick about pot specs, you should choose the specs that actually matter, such as finding a quality taper, and a good mechanical construction that will last over time.

 

[Cagey]

I really wanted to finish this build this weekend.  What would Jimmy Page do?  What would Cagey do? 

Jimmy would send his guitar to Cagey. Cagey would go to his parts inventory and grab the right parts. If there weren't any, he'd cuss up a storm and look around to see what else was short or empty, then get online and order what's needed.

I always use long shaft parts, regardless of whether it's a front/rear route. You can always add a stop nut to mount a long shaft in a shallow hole or on a pickguard (in fact, I prefer it - makes wiring easier), but you can't use a short shaft in a long hole.

Incidentally, what pickups are you putting in that fiddle? It looks like you've got single coil cavities, but be aware that most noiseless pickups are actually humbuckers in a different form factor, usually have a somewhat higher impedance and should probably use 500K rather than 250K pots.

 

[line6man]

Incidentally, what pickups are you putting in that fiddle? It looks like you've got single coil cavities, but be aware that most noiseless pickups are actually humbuckers in a different form factor, usually have a somewhat higher impedance and should probably use 500K rather than 250K pots.

That really comes down to preference. 500k is used to help preserve the treble on warmer humbuckers, whereas 250k is a popular choice for taming out ice-pick single coils. A particularly bright humbucker might be more musical with a 250k pot, but at the end of the day, its nothing to write home about. Personally, I use 500k pots on everything, regardless of the pickups, because there are 50 other ways to warm up a bright guitar, but no way to brighten a warm guitar.

 

[Cagey]

I agree, and do the same thing for the same reason. All 500K, and all long shaft.

 

[vikingred]

Buy the right pots for the body.

What are "impedance matched pots?" The resistance of a volume and tone control need not match, and if the actual value strays from the rating, due to a poor tolerance, then the effect will only be very subtle, if audible at all.

Yeah I figured that would be the answer.  Check here on impedance matching: https://en.wikipedia.org/wiki/Impedance_matching

You can get CTS pots that are tighter/matching impedances.  It's one of those things that's probably more a personal preference (subtle as it may be) but why not go for it.  The ones I have are .05% matched genuine CTS 450G Low Torque 250K split shaft audio taper volume and tone control pots.  I like them.

So I guess I get to order some 3/4" Les Paul 250k pots.  Wow.

You are mis-educating yourself. The link you posted is not applicable to this situation. Learn more about how these circuits work before trying to blindly follow academic literature.

Using 250k pots is not impedance matching. There are all sorts of different pickups out there, with vastly different impedances. Everyone uses either 250k or 500k pots with them, however, because the industry (or Leo Fender) decided that was the standard. If you really wanted to impedance match, you would wind up with some oddball value. But what you would gain from doing it would be questionable to begin with. The main thing that happens when you change the resistance of the volume pot is that the resonant frequency of the circuit shifts up and down, and the main thing that happens when you change the resistance of the tone pot is that a little more or less treble is cut. You are arbitrarily deciding what behavior is "right" for the circuit, and you are doing so in a circuit that can tolerate fairly large changes in resistance that won't be discerned by the ear. Try experimenting with changes in resistance, and you will find that the effect on the resonant response of the circuit, as well as the effect on the taper of the sweep, will only change in a very subtle way. Even making fairly large jumps, like going from 250k to 500k, only makes a subtle difference. If you are going to nit pick about pot specs, you should choose the specs that actually matter, such as finding a quality taper, and a good mechanical construction that will last over time.

Pardon me for getting into a pissing contest with you, however I believe it is you who are misinformed or perhaps you misunderstood my point of impedance matching.  My purpose of using impedance-matched pots has nothing do to with the pickups, or changes in resonance, arbitrary behavior of the circuit, or esoteric nuances of sound.  It has to do with consistency of proportion across pots on a particular guitar. As I'm certain you know, audio taper pots are made within various tolerances ranges: standard is +/- 20%, "Pro" grade is +10%/-10% etc.  Because I prefer consistency of proportion when I'm twisting knobs on my gear, I prefer to use pots and tone controls that are as close as possible in their tolerance ranges, and I have a source for CTS 450G low torque pots that are matched in sets of 3 to .05% -- presumably because the guy buys them in large quantities and doesn't mind sitting there with an ohm meter finding the ones that match the closest.  Unfortunately, that source does not carry long-shaft pots--thus the admittedly ridiculous late-night notion of countersinking upward from within the cavity.  In case you are still perplexed, let me give you another example.  My wife drives a Nissan Pathfinder.  I drive a Mercedes.  When I drive her vehicle I overshoot the gas and end up lurching forward because I am used to the gas pedal in my car.  If they were analogously "impedance matched" I could seamlessly switch back and forth and the variance in pressure applied would be nearly identical.  This, my guitar building friend, is what I prefer.  Volume-Tone-Tone impedance matching to .05%.  I have a sensitive ear and a sensitive hand, and it works for me.  That is all.

 

[vikingred]

I really wanted to finish this build this weekend.  What would Jimmy Page do?  What would Cagey do? 

Jimmy would send his guitar to Cagey. Cagey would go to his parts inventory and grab the right parts. If there weren't any, he'd cuss up a storm and look around to see what else was short or empty, then get online and order what's needed.

I always use long shaft parts, regardless of whether it's a front/rear route. You can always add a stop nut to mount a long shaft in a shallow hole or on a pickguard (in fact, I prefer it - makes wiring easier), but you can't use a short shaft in a long hole.

Incidentally, what pickups are you putting in that fiddle? It looks like you've got single coil cavities, but be aware that most noiseless pickups are actually humbuckers in a different form factor, usually have a somewhat higher impedance and should probably use 500K rather than 250K pots.

Cagey, it was late, and my mind was wandering.  I have a set of hand-wound "Dawgtown" oldschool, probably noisy-ass single coils built by a cool old retired cat that does nothing but pickups.  Check them out:

Here is the E-bay link: http://www.ebay.com/itm/Dawgtown-Aged-Late-64-Pickups-For-Strat-Stratocaster-USA-Hand-Wound-AlNiCo-5-/

So, I've got the back cavity coppered-up pretty solid, and probably will go with the 250k pots (long shaft), but will order some 500k's just to have one hand and check them out.  I'd love to let you do the work, but it's 50% of the fun for me.  The fret work is all you though, man.  I'm almost ready to ship you the first build (korina with EMG's) but I want to get this one done first.

Now I'm off to find a source for 10% tolerance CTS 450G long shaft 250k pots!  Peace.

 

[line6man]

Buy the right pots for the body.

What are "impedance matched pots?" The resistance of a volume and tone control need not match, and if the actual value strays from the rating, due to a poor tolerance, then the effect will only be very subtle, if audible at all.

Yeah I figured that would be the answer.  Check here on impedance matching: https://en.wikipedia.org/wiki/Impedance_matching

You can get CTS pots that are tighter/matching impedances.  It's one of those things that's probably more a personal preference (subtle as it may be) but why not go for it.  The ones I have are .05% matched genuine CTS 450G Low Torque 250K split shaft audio taper volume and tone control pots.  I like them.

So I guess I get to order some 3/4" Les Paul 250k pots.  Wow.

You are mis-educating yourself. The link you posted is not applicable to this situation. Learn more about how these circuits work before trying to blindly follow academic literature.

Using 250k pots is not impedance matching. There are all sorts of different pickups out there, with vastly different impedances. Everyone uses either 250k or 500k pots with them, however, because the industry (or Leo Fender) decided that was the standard. If you really wanted to impedance match, you would wind up with some oddball value. But what you would gain from doing it would be questionable to begin with. The main thing that happens when you change the resistance of the volume pot is that the resonant frequency of the circuit shifts up and down, and the main thing that happens when you change the resistance of the tone pot is that a little more or less treble is cut. You are arbitrarily deciding what behavior is "right" for the circuit, and you are doing so in a circuit that can tolerate fairly large changes in resistance that won't be discerned by the ear. Try experimenting with changes in resistance, and you will find that the effect on the resonant response of the circuit, as well as the effect on the taper of the sweep, will only change in a very subtle way. Even making fairly large jumps, like going from 250k to 500k, only makes a subtle difference. If you are going to nit pick about pot specs, you should choose the specs that actually matter, such as finding a quality taper, and a good mechanical construction that will last over time.

Pardon me for getting into a pissing contest with you, however I believe it is you who are misinformed or perhaps you misunderstood my point of impedance matching.  My purpose of using impedance-matched pots has nothing do to with the pickups, or changes in resonance, arbitrary behavior of the circuit, or esoteric nuances of sound.  It has to do with consistency of proportion across pots on a particular guitar. As I'm certain you know, audio taper pots are made within various tolerances ranges: standard is +/- 20%, "Pro" grade is +10%/-10% etc.  Because I prefer consistency of proportion when I'm twisting knobs on my gear, I prefer to use pots and tone controls that are as close as possible in their tolerance ranges, and I have a source for CTS 450G low torque pots that are matched in sets of 3 to .05% -- presumably because the guy buys them in large quantities and doesn't mind sitting there with an ohm meter finding the ones that match the closest.  Unfortunately, that source does not carry long-shaft pots--thus the admittedly ridiculous late-night notion of countersinking upward from within the cavity.  In case you are still perplexed, let me give you another example.  My wife drives a Nissan Pathfinder.  I drive a Mercedes.  When I drive her vehicle I overshoot the gas and end up lurching forward because I am used to the gas pedal in my car.  If they were analogously "impedance matched" I could seamlessly switch back and forth and the variance in pressure applied would be nearly identical.  This, my guitar building friend, is what I prefer.  Volume-Tone-Tone impedance matching to .05%.  I have a sensitive ear and a sensitive hand, and it works for me.  That is all.

So what you are saying is that you want consistency across all of your gear, so that the perceived tapers will match, when switching instruments? If this is the case, then you definitely don't want to be using the same resistance for everything. You are not accounting for the fact that the behavior of the pots is influenced by the impedance of the signal. If you want consistency, then you use different value pots, depending on the nature of the impedance of each circuit.

 

[vikingred]

Buy the right pots for the body.

What are "impedance matched pots?" The resistance of a volume and tone control need not match, and if the actual value strays from the rating, due to a poor tolerance, then the effect will only be very subtle, if audible at all.

Yeah I figured that would be the answer.  Check here on impedance matching: https://en.wikipedia.org/wiki/Impedance_matching

You can get CTS pots that are tighter/matching impedances.  It's one of those things that's probably more a personal preference (subtle as it may be) but why not go for it.  The ones I have are .05% matched genuine CTS 450G Low Torque 250K split shaft audio taper volume and tone control pots.  I like them.

So I guess I get to order some 3/4" Les Paul 250k pots.  Wow.

You are mis-educating yourself. The link you posted is not applicable to this situation. Learn more about how these circuits work before trying to blindly follow academic literature.

Using 250k pots is not impedance matching. There are all sorts of different pickups out there, with vastly different impedances. Everyone uses either 250k or 500k pots with them, however, because the industry (or Leo Fender) decided that was the standard. If you really wanted to impedance match, you would wind up with some oddball value. But what you would gain from doing it would be questionable to begin with. The main thing that happens when you change the resistance of the volume pot is that the resonant frequency of the circuit shifts up and down, and the main thing that happens when you change the resistance of the tone pot is that a little more or less treble is cut. You are arbitrarily deciding what behavior is "right" for the circuit, and you are doing so in a circuit that can tolerate fairly large changes in resistance that won't be discerned by the ear. Try experimenting with changes in resistance, and you will find that the effect on the resonant response of the circuit, as well as the effect on the taper of the sweep, will only change in a very subtle way. Even making fairly large jumps, like going from 250k to 500k, only makes a subtle difference. If you are going to nit pick about pot specs, you should choose the specs that actually matter, such as finding a quality taper, and a good mechanical construction that will last over time.

Pardon me for getting into a pissing contest with you, however I believe it is you who are misinformed or perhaps you misunderstood my point of impedance matching.  My purpose of using impedance-matched pots has nothing do to with the pickups, or changes in resonance, arbitrary behavior of the circuit, or esoteric nuances of sound.  It has to do with consistency of proportion across pots on a particular guitar. As I'm certain you know, audio taper pots are made within various tolerances ranges: standard is +/- 20%, "Pro" grade is +10%/-10% etc.  Because I prefer consistency of proportion when I'm twisting knobs on my gear, I prefer to use pots and tone controls that are as close as possible in their tolerance ranges, and I have a source for CTS 450G low torque pots that are matched in sets of 3 to .05% -- presumably because the guy buys them in large quantities and doesn't mind sitting there with an ohm meter finding the ones that match the closest.  Unfortunately, that source does not carry long-shaft pots--thus the admittedly ridiculous late-night notion of countersinking upward from within the cavity.  In case you are still perplexed, let me give you another example.  My wife drives a Nissan Pathfinder.  I drive a Mercedes.  When I drive her vehicle I overshoot the gas and end up lurching forward because I am used to the gas pedal in my car.  If they were analogously "impedance matched" I could seamlessly switch back and forth and the variance in pressure applied would be nearly identical.  This, my guitar building friend, is what I prefer.  Volume-Tone-Tone impedance matching to .05%.  I have a sensitive ear and a sensitive hand, and it works for me.  That is all.

So what you are saying is that you want consistency across all of your gear, so that the perceived tapers will match, when switching instruments? If this is the case, then you definitely don't want to be using the same resistance for everything. You are not accounting for the fact that the behavior of the pots is influenced by the impedance of the signal. If you want consistency, then you use different value pots, depending on the nature of the impedance of each circuit.

Nope, you're still not getting it, maybe my car analogy wasn't a good example.  Pretend each of the three pots on a strat was a gas pedal.  I want my pots in each guitar to be as close to identical in impedance as possible. What I prefer is consistency (impedance matching) across the pots in each particular guitar (usually three in a classic strat, in the case of this build, two).  That's why I buy them in matched sets of three (per guitar).  And though I didn't want to get into technical debate, tighter tolerances do prevent tone loss from load mismatches and low pot values.  I am new to building guitars but not new to upgrading strat electronics.

 

[line6man]

Buy the right pots for the body.

What are "impedance matched pots?" The resistance of a volume and tone control need not match, and if the actual value strays from the rating, due to a poor tolerance, then the effect will only be very subtle, if audible at all.

Yeah I figured that would be the answer.  Check here on impedance matching: https://en.wikipedia.org/wiki/Impedance_matching

You can get CTS pots that are tighter/matching impedances.  It's one of those things that's probably more a personal preference (subtle as it may be) but why not go for it.  The ones I have are .05% matched genuine CTS 450G Low Torque 250K split shaft audio taper volume and tone control pots.  I like them.

So I guess I get to order some 3/4" Les Paul 250k pots.  Wow.

You are mis-educating yourself. The link you posted is not applicable to this situation. Learn more about how these circuits work before trying to blindly follow academic literature.

Using 250k pots is not impedance matching. There are all sorts of different pickups out there, with vastly different impedances. Everyone uses either 250k or 500k pots with them, however, because the industry (or Leo Fender) decided that was the standard. If you really wanted to impedance match, you would wind up with some oddball value. But what you would gain from doing it would be questionable to begin with. The main thing that happens when you change the resistance of the volume pot is that the resonant frequency of the circuit shifts up and down, and the main thing that happens when you change the resistance of the tone pot is that a little more or less treble is cut. You are arbitrarily deciding what behavior is "right" for the circuit, and you are doing so in a circuit that can tolerate fairly large changes in resistance that won't be discerned by the ear. Try experimenting with changes in resistance, and you will find that the effect on the resonant response of the circuit, as well as the effect on the taper of the sweep, will only change in a very subtle way. Even making fairly large jumps, like going from 250k to 500k, only makes a subtle difference. If you are going to nit pick about pot specs, you should choose the specs that actually matter, such as finding a quality taper, and a good mechanical construction that will last over time.

Pardon me for getting into a pissing contest with you, however I believe it is you who are misinformed or perhaps you misunderstood my point of impedance matching.  My purpose of using impedance-matched pots has nothing do to with the pickups, or changes in resonance, arbitrary behavior of the circuit, or esoteric nuances of sound.  It has to do with consistency of proportion across pots on a particular guitar. As I'm certain you know, audio taper pots are made within various tolerances ranges: standard is +/- 20%, "Pro" grade is +10%/-10% etc.  Because I prefer consistency of proportion when I'm twisting knobs on my gear, I prefer to use pots and tone controls that are as close as possible in their tolerance ranges, and I have a source for CTS 450G low torque pots that are matched in sets of 3 to .05% -- presumably because the guy buys them in large quantities and doesn't mind sitting there with an ohm meter finding the ones that match the closest.  Unfortunately, that source does not carry long-shaft pots--thus the admittedly ridiculous late-night notion of countersinking upward from within the cavity.  In case you are still perplexed, let me give you another example.  My wife drives a Nissan Pathfinder.  I drive a Mercedes.  When I drive her vehicle I overshoot the gas and end up lurching forward because I am used to the gas pedal in my car.  If they were analogously "impedance matched" I could seamlessly switch back and forth and the variance in pressure applied would be nearly identical.  This, my guitar building friend, is what I prefer.  Volume-Tone-Tone impedance matching to .05%.  I have a sensitive ear and a sensitive hand, and it works for me.  That is all.

So what you are saying is that you want consistency across all of your gear, so that the perceived tapers will match, when switching instruments? If this is the case, then you definitely don't want to be using the same resistance for everything. You are not accounting for the fact that the behavior of the pots is influenced by the impedance of the signal. If you want consistency, then you use different value pots, depending on the nature of the impedance of each circuit.

Nope, you're still not getting it, maybe my car analogy wasn't a good example.  Pretend each of the three pots on a strat was a gas pedal.  I want my pots in each guitar to be as close to identical in impedance as possible. What I prefer is consistency (impedance matching) across the pots in each particular guitar (usually three in a classic strat, in the case of this build, two).  That's why I buy them in matched sets of three (per guitar).  And though I didn't want to get into technical debate, tighter tolerances do prevent tone loss from load mismatches and low pot values.  I am new to building guitars but not new to upgrading strat electronics.

But each pot is doing something different. Volume controls are wired very differently than tone controls, and if you had multiple volumes or tones, then the impedance of each signal would be different. So there is no consistency at all unless you tailor each pot to the task it is wired to do.

In any case, I'm not going to waste time arguing. Your best bet is to buy long shaft pots. You can find them in whatever resistance, taper, and tolerance you want, if you look around.

 

[mayfly]

The electrical engineer in me is watching all this with a bemused expression.

Hey Line6man - try not to get dragged into every crazy assed thing out there buddy  ccasion14:

Hey Vikingred - Nice guitar.  Do what makes you happy.  And, (I know I'm gonna regret this) here's pot that should work in your application:
http://www.ebay.com/itm/ALPS-RK50-rotary-Potentiometer-10K-50K-100K-250K-logarithmic-pot-Japan-RK50112-/351409765007?hash=item51d1a77a8f

 

[vikingred]

The electrical engineer in me is watching all this with a bemused expression.

Hey Line6man - try not to get dragged into every crazy assed thing out there buddy  ccasion14:

Hey Vikingred - Nice guitar.  Do what makes you happy.  And, (I know I'm gonna regret this) here's pot that should work in your application:
http://www.ebay.com/itm/ALPS-RK50-rotary-Potentiometer-10K-50K-100K-250K-logarithmic-pot-Japan-RK50112-/351409765007?hash=item51d1a77a8f

Nice!  I can laugh at myself.  This thread did get a bit nuts.  And I'm certainly nuts.  But, we're having fun aren't we?  :toothy12:

 

[stratamania]

Another practical possibility.


Send it to Cagey, to do the fretwork.
Order pots of preference.

Guitar returns from Cagey, drop in pots that by now could have been to a large degree pre wired and the jobs done.

 

[vikingred]

Another practical possibility.


Send it to Cagey, to do the fretwork.
Order pots of preference.

Guitar returns from Cagey, drop in pots that by now could have been to a large degree pre wired and the jobs done.

Gotta send my first build into Cagey first.  Then this one.  Like I said, I'm a nut.  Incidentally, did you see this:

http://unofficialwarmoth.com/index.php?topic=25571.0

Now that, my friend, is gonna be SPECIAL.

 

[Cagey]

I am standing here beside myself!​

 

[stratamania]

@vikingred, yes I saw her and a nice set of parts and woods. Interested to see what you do with them.  :icon_thumright:

@Cagey, Johnny Five is alive