# Choosing the right potentiometer.



## Rick31797 (Apr 20, 2007)

I have a EPI Nighthawk that i believe deserves an upgrade and it plays so nice.. These guitars have 3 pickups.
1 volume pot 
1 tone pot with push pull
5 way select switch.
The pickups , neck- mini humbucker, middle - single coil and bridge humbucker..

I am just changing the bridge pickup, and all pots, 5 way switch and input jack replaced.

The humbucker can be switched to single coil with the push pull tone knob.

Should the volume pot and the push and pull tone knob , both be 500 ohms...


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## greco (Jul 15, 2007)

What did the factory installed pots measure?
If you want the same sound, I would stay with whatever the manufacturer used.
I suspect that both will be 500Kohms

Edit: I tried to search/find it and had no luck.


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## mhammer (Nov 30, 2007)

I've blathered on about it before, but I suppose one more time couldn't hurt....

The "ideal" pots will depend on how you tend to use your volume control. When the volume is turned up full, a 500k pot will load down your pickups less than a 250k one will. This is why users of single coils will tend to go for 250k to shave off a bit of the glassiness, while humbucker-users will tend to go for 500k, to hang onto the limited top end that HBs tend to display.

HOWEVER...as great and appropriate as this is, if you are the sort of player that dickers around with your volume control constantly or regularly, the benefits of higher-value volume pots quickly disappear the moment you turn down a bit.

As long as it is connected, and regardless of its value, your Tone pot is _always_ bleeding highs. If the pot value is high enough and the cap value suitable for the pickups, you won't be bleeding any HF content that poses a serious loss or problem. Some folks like to have a "no-load" Tone pot that completely disconnects the pot when turned up full. The difference between leaving the tone control in circuit or disconnecting it fully can be noticeable, though whatever gets restored via disconnection has to still be useful to you or else there is no advantage.

Depending on the pickup tone and how much you like to have high end on tap, a 250k could be better for you...or not. Again, if you tend to work your Volume pot regularly, the "advantages" of 500k will be barely noticeable. What becomes more important under those circumstances is the feel of the pot and the taper. That is, it feels smooth when you turn it, and the different positions yield audible differences in level, with no zones where you seem to get the same level despite a bit of rotation.


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## Guest (Feb 15, 2017)

I've googled this and have talked with those who know.
But, I'm still somewhat confused about linear vs audio pots and best uses of each.
ie; audio for volume, linear for tone. Depending on how you prefer your roll off.
Mark, or anyone else, can you explain pros/cons of situations for each?
Would be much appreciated.


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## mhammer (Nov 30, 2007)

Volume should nearly always be log/audio.

Tone will depend on how the individual player uses it. Myself, I like to use a 1meg linear, with a different-value cap from each outside lug to ground - the wiper tied to the input lug of the volume pot. 

It does two things:
1) It provides two different rolloffs; one for traditional muted tone, and another for "rounding off" the tone without losing much midrange. Alternatively, a person could use a cap and inductor for a mid-cut in one of the directions.
2) It halves the amount of rotation required to go from no cut to max of either type of cut. If your Tone pot is in the right location, you can use your pinky to make it go "wah".

I suppose ideally one might want a W-taper pot for this (i.e., log or anti-log as one moves away from the midpoint) with a center detente to easily return to full treble. On the other hand, when the distance to be travelled is cut in half, taper matters less since you can easily get to the setting you want anyway. Linear simply gives me the same resistance and taper from each side of the midpoint.

But you asked a theory question about taper....

If you're oneof those players who rarely turns Tone down from max, except to completely mute things and momentarily eliminate audible buzz, then taper doesn't matter becaue you'll be using max, min, and very little in between.

If you're a player that uses single coils, and likes to have a broad variety of tones on tap, taper starts to matter more, since it will provide the optimum amount of diability and precision to nail just the right amount of top end for your tastes. It will also depend on the cap value. If you use a cap value like .022-.05uf, you'll want a taper that lets you ease into maximum cut, because you'll be interested in settings that are a bit less than full cut. That will recommend log taper, since the smaller resistances will be spread over a broader rotation. If you use a smaller cap value, like .01uf, you may find a linear moves you around the zone more easily. Again, "best" taper depends on how you use it and the way you play with varying tones as you play.

Make sense?


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## Granny Gremlin (Jun 3, 2016)

laristotle said:


> I've googled this and have talked with those who know.
> But, I'm still somewhat confused about linear vs audio pots and best uses of each.
> ie; audio for volume, linear for tone. Depending on how you prefer your roll off.
> Mark, or anyone else, can you explain pros/cons of situations for each?
> Would be much appreciated.


Generally, for anything audio-related you want log (audio) taper. For typical passive guitar wiring, if you like very little treble bleed/rolloff from about 1-8.5 on the tone knob and then drop off a cliff from 9-10, then sure maybe try a linear. Some people find they like this 'finer control' on the earlier travel of the tone knob helps them find their sweet spot better; depends where the sweet spot is for you. If you just want to take the edge off (sitting at about 1-3) it's worth a try (you'll end up setting it around 5-7, for example), but if you generally roll off tone a lot, 5 or up, it likely won't work for you as all that travel from 5-10 will be squeezed into 8-10 at best.

There are some guitars that use linear pots stock - see the Jazzmaster as a notable example. I suspect that the reason for this may have something to do with the trouble getting quality 1Meg Log pots back in the day (goes double for the thumbwheel rhythm circuit pots). It's good to remember that the top mod to Jazzmasters is to redo the circuit... and that the lin pots were the vol (the full size tone pot is log/audio; thumbwheels are both lin, as I mentioned, probably due to availability, and then it just stuck).

edit: mhammer explained it from a more technical point of view as I typed that; I assumed standard 0.022-0.047 tone pot for simplicity.


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## Rick31797 (Apr 20, 2007)

So i got all the parts needed to change the volume, tone and 5 way switch ..and i am already at a loss on what to do..
The 5 way switch is different which means i just cannot copy what is in front of me..The old one has wires solder to a ground...but i see nothing on the new one..

My first upgrade for a guitar and it would have to have a complicated wiring..this has 3 pickups so between the 5 way and push/pull you end up with 10 different tones..

Is there a place i can go to see how they are wiring this switch and grounding...


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## greco (Jul 15, 2007)

Look through here for the switch wiring comparisons. Hopefully,that will get you started.

5 way guitar switch wiring - Google Search

Do you have a (stock/factory) wiring diagram for an Epi Nighthawk?


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## Rick31797 (Apr 20, 2007)

I will look for the stock wiring diagram...this new 5 way switch has 8 pieces to attach wires but not one of them tell me a ground wire should attach here..


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## Rick31797 (Apr 20, 2007)

This diagram is as close as i can find...it shows no ground wire going to the 5 way blade switch...


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## Rick31797 (Apr 20, 2007)

What has got me is the yellow wire from a pickup..one wire solders to a pole on the 5 way switch, the other wire attach to a pole sticking out of the body..acting as a ground..

my new 5 way has nothing to solder the ground too.


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## greco (Jul 15, 2007)

If you want to attach a ground to the switch, you can simply solder it to the baseplate of the switch. I don't think it is needed ...but I'm not familiar with this guitar.


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## greco (Jul 15, 2007)

Rick31797 said:


> the other wire attach to a pole sticking out of the body...


Are you talking about the "body" of the switch? ...or the "body" of the guitar?
I'm assuming switch.


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## greco (Jul 15, 2007)

I think I get what is happening here...

Is the black wire soldered to the same ground point and going from the switch to the back of the volume pot? If so, that is just one way of approaching the need to ground the shield of the pickup wire (inside the yellow wire) to the entire grounding "system" of the guitar. Am I making any sense to you?



















BTW...Don't get too frustrated. Guitar wiring can be confusing and a pain to sort out. Especially since this is your first time trying it...Correct?


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## greco (Jul 15, 2007)

Rick31797 said:


> This diagram is as close as i can find...it shows no ground wire going to the 5 way blade switch...


I tried to save and enlarge this diagram ...no luck.


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## Rick31797 (Apr 20, 2007)

You are correct...that black wire goes back to the volume pot...

I think the safe thing to do is cut the pickup wires, take the wiring harness out of the guitar and then set up my new parts and copy the wiring, and see how it works, without messing up the old wiring harness, i cannot find the wiring diagram for this guitar..


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## greco (Jul 15, 2007)

Rick31797 said:


> You are correct...that black wire goes back to the volume pot...
> 
> I think the safe thing to do is cut the pickup wires, take the wiring harness out of the guitar and then set up my new parts and copy the wiring, and see how it works, without messing up the old wiring harness, i cannot find the wiring diagram for this guitar..


Sounds like an excellent plan!

You do not need to solder the shield/braid of the pickup wire to the switch. However, *you do need to solder it to ground somwhere*...hence the black wire going to the back of the volume pot.

Keep us updated on how everything progresses. Good Luck!!

I'm very pleased that you weren't asking about push-pull pots. I don't do well with those. I was helping forum member @laristotle wire a guitar for his friend and it involved push-pull pots. Almost did me in! @laristotle solved the problem and "saved the day".


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## High/Deaf (Aug 19, 2009)

Soldering the braid to a pot can be tricky. You need a lot of heat to get the large surface of the pot hot enough to flow solder - and that often means over-heating the braid and melting the insulation between it and the center conductor. One trick is to wrap a wire (insulated solid or stranded) around the braid without unbraiding it and solder that first - that doesn't take nearly as much heat and is less like to melt the insulation. Then solder the other end of that wire to the back of the pot. If the wire is a few inches long, less heat will make it up the conductor to the braid. 

And as I mentioned a number of times before, the best way to solder to a large surface like a pot is using a much larger spade tip. That is more important than how hot it is. It is a large mass and contains a lot of thermal energy that will heat the pot up quickly (like 1 -2 seconds). Most irons have replaceable tips so you have to wait for it to cool down between solder jobs. You don't want to use the big spade tip for small work, like the pot lugs or switch connections, you want a small pointy tip.

I usually heat up two irons so I don't have to wait for cool-down.


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## mhammer (Nov 30, 2007)

I don't know how much soldering you expect to do for the rest of your life, but a little bottle of liquid flux can be an absolute lifesaver. Smearing a bit on the part of the braid you want to solder will speed things up immensely. The bottle will probably set you back ten bucks or so, but unless you spill it (DON'T, it is an absolute nightmare to clean up), it will probably last you until the grave if you're a hobbyist rather than a repair bench or manufacturer.

Pots vary in the material used for the back cover. In some instances the metal used is not receptive to solder at all. In such instances, it may even be better and easier to solder the braid to a washer, slip the washer over the threaded collar of the pot and let the contact between the washer and all the other outside parts of the pot do the connecting for you.

If the pot cover IS amenable to solder, scrape off some of the surface with an X-acto blade or utility knife. Smear a bit of liquid solder flux on the area, and apply a decent blob of solder to the area first. Then, when you take the tinned piece of braid, and attempt to solder it to the pot, the heat will be more localized to that blob of solder and it will liquefy quickly.


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## greco (Jul 15, 2007)

mhammer said:


> If the pot cover IS amenable to solder, scrape off some of the surface with an X-acto blade or utility knife. Smear a bit of liquid solder flux on the area, and apply a decent blob of solder to the area first. Then, when you take the tinned piece of braid, and attempt to solder it to the pot, the heat will be more localized to that blob of solder and it will liquefy quickly.


This is the method I have always used and it works fine for me...even with a wetted, pointed tip instead of a chisel tip.

I bought a flux pen that looks something like this..









As @mhammer wrote, it has lasted me for years. As he also wrote, it is amazingly sticky stuff if you get any on you, your clothes, etc. I have used 100% alcohol to clean it. You can also use the same alcohol and a Q-tip to clean the brown flux residue on the solder joint after it cools.

This is how I prefer to prepare any sheathed wire for soldering the ground.
Just remove it to one side and twist it..then tin it, trim it to length and solder to whatever. Admittedly, there are many equally excellent alternate approaches. 









Cheers

Dave


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## Rick31797 (Apr 20, 2007)

Thanks everyone for all your help, i think i can do this now..


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## High/Deaf (Aug 19, 2009)

Yes, I would also always tin the pot first, and use flux. I still use a tip with a large thermal mass so I'm only heating for a second or less as I attach the braid or wire. This is the step where you want to minimize the time so the heat doesn't melt anything unintentionally. I've never had a pot that didn't tin and I don't recall ever having to scrape one to get solder to stick - perhaps it's the pots I have experience with or perhaps it's the large tip that just won't take 'no' for an answer. And clean with isopropyl afterwards to remove excess flux, because it's sticky and will pick up dirt, etc. 

As said, the flux is (or at least used to be) made from tree sap, or so I heard. It certainly has the properties of sap. Nasty stuff if you spill it.


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## mhammer (Nov 30, 2007)

Though the bent-wire tip solder "guns" are not recommended for use on a great many things (circuit boards especially), the speed with which they heat up and the surface which they can apply heat over, is a great help when soldering anything big enough to dissipate heat faster than a soldering iron/pen can apply it. Great for working on tube amps, and great for soldering braid to the back of a pot.


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## greco (Jul 15, 2007)

Rick31797 said:


> Thanks everyone for all your help, i think i can do this now..


Please bear with us..we are on a roll here.


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## knight_yyz (Mar 14, 2015)

Sorry this is so big. These are life savers if you can't solder to the pot. Solder the ground to these. And plus one on the liquid flux. Get a bottle with a needle. I've used paste and liquid, and I prefer the liquid


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## mhammer (Nov 30, 2007)

Good call, on all counts.


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## greco (Jul 15, 2007)

knight_yyz said:


> Sorry this is so big. These are life savers if you can't solder to the pot. Solder the ground to these. And plus one on the liquid flux. Get a bottle with a needle. I've used paste and liquid, and I prefer the liquid


Great find! 

What are the approximate dimensions of these AND where do you get them from?

Thanks


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## Guest (Mar 6, 2017)

pop cans? lol.


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## greco (Jul 15, 2007)

laristotle said:


> pop cans? lol.


You, my friend, are brilliant!!!

I'm going to try and solder a wire to one of these...just for fun.
Edit: It wouldn't solder for me.


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## knight_yyz (Mar 14, 2015)

If you google solder lugs these will pop up. But there are multiple sizes. We need 3/8 for a typical North American pot. You can google pot solder lugs and the right size should come up. I ordered 10 from ebay. As you can see the Bourn pots do not allow you to solder to the actual pot in this style so I have 2 solder lugs for the grounds which are very hard to see in the pic.


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