# Potentiometer values and tone-250 k and 500k



## Doug B (Jun 19, 2017)

I just bought some Zexcoil pickups-a Z-Core5 Modern and 2 x Z Core5 vintage.

Zexcoil recommends to use 500k pots, but I have heard that 250k pots are appropriate for Strat pickups.

Would changing to 500 k pots increase the highs or decrease them?

Thanks.

Doug


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## GTmaker (Apr 24, 2006)

I would match pots to the specs of the pickups NOT the guitar body style.
IF you want to mess around with tone, 
look at different caps values and see which ones fit you best.
G.


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## Doug B (Jun 19, 2017)

GTmaker said:


> I would match pots to the specs of the pickups NOT the guitar body style.
> G.


I wasn't talking about the body style, I meant that 250k pots are usually for single coils, 500 k pots are usually for humbuckers.
Zexcoil recommends 500k pots for the pickups that I purchased (Z Core5 Vintage and ZCore 5 Modern) The pickups are single coil shaped, but use a different technology(see zexcoil.com ) So I find myself wondering what to use.

And no, I am not interested in experimenting, just getting the best sound out of these pickups.


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## keto (May 23, 2006)

500K definitely more highs available.


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## greco (Jul 15, 2007)

Doug B said:


> The pickups are single coil shaped, but use a different technology(see zexcoil.com ) So I find myself wondering what to use.


Very interesting design concept!

The 500K pots should retain the highs. 
A 250K pot will warm it up, if it sounds too bright.
As @GTmaker states, caps values can certainly influence this.


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## StratCat (Dec 30, 2013)

There is a reason the manufacturer is recommending a specific rating on the potentiometers. It is extremely likely they have tested multiple configurations to base this on.

Contact them and ask why they recommend this and what their thoughts are on the use of the industry standard 250k pots (for single coil pickups) with their zex coil pickups.


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## JHarasym (Mar 27, 2007)

I was under the impression that a pot removes high frequencies, and when it is "off" (eg on 10) the full frequency range passes.
Does this not imply that either 250 or 500k pot will sound the same in the "off" position?


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## greco (Jul 15, 2007)

StratCat said:


> Contact them and ask why they recommend this and what their thoughts are on the use of the industry standard 250k pots (for single coil pickups) with their zex coil pickups.


@StratCat 's suggestion is very wise and logical, IMO. 
I should learn to take this approach more often myself.

@Doug B If you do decide to contact Zexcoil, could you please consider posting their response in this thread. Thanks.


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## Granny Gremlin (Jun 3, 2016)

greco said:


> Very interesting design concept!


Yep, not new though; individual coils per string have been done before. Earliest that I know of was the Gibson EB4L bass (4 coils in a kinda split P arrangement). Then most Wal basses had 2 coils per string (humbucker). After that I lost track, but I think there was a guitar with individual outputs per string.


















To the OP; with multiple coils like this, it likely is a humbucker (it makers little sense for it not to be, because, who likes hum); use 500K. Especially since the manufacturer says so. Form factor is meaningless.

If you do email them to ask why, that is the short answer they will give you. The other possible reason is that with more coils you have more wire which equals a higher DCR for the pickup than a reg single coil (or even reg bucker). .... but it is possible to mitigate that.... they don't posty the spec (or I couldn't find it in a quick check of their site), but from what they do say maybe it's not that high.


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## mhammer (Nov 30, 2007)

Higher-resistance pots will load down subsequent stages less, whether amp or pedal. That will, in principle, result in preservation of high end. If the pickup's high end is objectionable for some reason, then using a lower-value volume pot will yield a "productive loading" that shaves off the objectionable high end. Since a Fender single-coil through a Fender amp can produce some serious top end, many players, in addition to the manufacturer, use a 250k volume pot with SC pickups. That top end can be shaved off in many ways. One of the reasons why Jimi Hendrix used a curly cable was to tame the top end from his Strat; curly cables having noticeably greater cable capacitance, causing treble loss.

But here is the thing: _the loading/unloading created by the pot is only in effect with the volume pot turned up full_. Turn it down a bit, and you're back to loading again. And if a 250k pot loads down a pickup more, then turning that pot down yields undesirable loading. This is why many Fenders have a bypass cap on the volume pot, in order to hang onto the treble you want, as you turn down.

And here is another thing: unless you have gobs of money, there are no guitar pots in between 250k and 500k (Gibsom made something that was 300k but I gather those are no longer standard). So, if your particular tastes, pickups, and amp suggest some other load, you're S.O.L.

Which suggest an alternate strategy....

Use a 500k, or even 1M volume pot. This will permit maximum upper treble retention. After all, you can't custom tailor what you never had. From the hot lug of the volume pot, one can connect any of a variety of small-value caps to ground; either on their own or in series with a resistor to custom-tailor the treble-trimming. The range of possible cap values alone will provide plenty of fine-tuning. Adding a series resistance on top of the cap increases that custom-tailoring even more.

Your Tone control is simply a variable resistance from that same hot lug in series with a treble-bleed cap to ground. What I described above is also a treble-bleed, except targetting much higher frequencies than the Tone control does. This is actually a more common strategy than you'd think. The acclaimed Analogman King of Tone? It uses a dual treble bleed approach. What it labels as "Presence" is simply an additional treble bleed control, aimed at the very top end, to filter out the fizzies. The "Tone" control trims stuff below that. What I described for your guitar is an identical approach.

Your volume pot will still produce loading and treble loss even with this mod, regardless of pot value. So, if you are the sort of player who fiddles with their volume a lot, you will likely want a Fender-style bypass cap on the volume. If you only tend to turn down your guitar so you can hear the phone, then no bypass cap is needed.


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## Doug B (Jun 19, 2017)

greco said:


> @Doug B If you do decide to contact Zexcoil, could you please consider posting their response in this thread. Thanks.



Scott at zexcoil got back to me this morning and recommended that I stay with 250k pots that I have now. Thanks everyone.


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