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Regular Contributor
Posts: 201
Registered: ‎07-11-2007

Sharp dropoff on tone cap?

Just redid my strat with GFS TX pups, 250k alpha pots, and sprague orange drop cap(got everything from GFS). I followed this seymour duncan wiring diagram: 3 single coils, one vol, 1 tone, 5-way Also lined the inner cavity with copper tape, underside of pickguard is aluminum foiled. While everything came out really well for some reason the tone knob is not very smooth. It sounds like it usn't turned down at all until right at the end of the knob and then it finally rolls off the treble all at once. The volume kknob is very smooth and even. What could be the issue with the tone knob? Does anyone know why what should be good components are acting this way? Thanks, any help appreciated!
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Super Contributor
amp_surgeon
Posts: 1,834
Registered: ‎11-13-2007

Re: Sharp dropoff on tone cap?

Sounds like you might have used an audio taper pot for the tone control. Look on the face of the pot, next to the shaft. Does it say B250K or A250K?
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Super Contributor
Posts: 1,599
Registered: ‎11-12-2008

Re: Sharp dropoff on tone cap?

Sounds like you might have used an audio taper pot for the tone control. Look on the face of the pot, next to the shaft. Does it say B250K or A250K?

+1

Sounds like you need a linear taper pot for the tone to me as well.
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Super Contributor
katillac
Posts: 6,352
Registered: ‎04-06-2008

Re: Sharp dropoff on tone cap?

In the past year, I started using linear pots for both volume and tone. I don't like that quick transition that comes with logarthymic (audio) pots.
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Regular Contributor
Posts: 201
Registered: ‎07-11-2007

Re: Sharp dropoff on tone cap?

Thanks guys, you are right I ordered two of the same pots (audio). Do you think that if I just went to radio shack their 250k linear pots would be decent enough to use?
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Occasional Contributor
RXVL
Posts: 10
Registered: ‎02-28-2009

Re: Sharp dropoff on tone cap?

Radio Shack wouldn't have threaded 250K linear pots. Check the website.
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Super Contributor
amp_surgeon
Posts: 1,834
Registered: ‎11-13-2007

Re: Sharp dropoff on tone cap?

RXVL is correct. Radio Shack doesn't carry anything between 100K and 1M in their 24mm linear panel mounting pots.
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Regular Contributor
Posts: 201
Registered: ‎07-11-2007

Re: Sharp dropoff on tone cap?

Hey can you guys recommend a site with good quality linear and audio taper pots, 250 & 500k? They places I usually go only seem to carry audio taper.

Thanks!
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Super Contributor
amp_surgeon
Posts: 1,834
Registered: ‎11-13-2007

Re: Sharp dropoff on tone cap?

Mouser Electronics (mouser.com). Stock number 31VA503-F. It's an Alpha brand, just like the ones you originally used, but linear taper.
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Super Contributor
katillac
Posts: 6,352
Registered: ‎04-06-2008

Re: Sharp dropoff on tone cap?

I second Mouser. At first, searching there can be a little intimidating, but with a little practice, it gets easier. Really good service and fast shipping, too. My other choice is bgmicro.com. They're a small business, so I like to support them when I can, and their service is top notch. The chick who usually answers the phone (Tammy) has been there for a long time and really knows her stuff in case you need to ask a question. :thu:
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Regular Contributor
Posts: 201
Registered: ‎07-11-2007

Re: Sharp dropoff on tone cap?

You guys are the best, thanks for all the help! I was able to get the pots I need off of mouser (mostly due to your recommendations since the site is so dificult to navigate).

Thanks again!
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Super Contributor
amp_surgeon
Posts: 1,834
Registered: ‎11-13-2007

Re: Sharp dropoff on tone cap?

Here's some helpful advice for using Mouser:

Don't "shop" on the website. They carry tens of thousands of items, and the site is not exactly set up for browsing. What it's really good for is when you already KNOW the stock numbers, and you're ready to place an order.

On the other hand, the Mouser catalog is great for browsing. It's categorized, and there's pictures of each type of component. For example, browse to the "passive components" chapter and you'll see a section for potentiometers. Open that section, and you'll see a section for Alpha components. Open that section, and you'll see a list of pages. Start at the first page in the list until you find the section for 24mm pots. Look for the picture of the pot you want, and then find it in the list with the value and taper you need. The part number is a web link to the corresponding page on the web site.

The catalog file is huge - 240MB and growing - but it's worth a download every couple of months if you're going to be ordering parts on a regular basis.
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Regular Contributor
Posts: 201
Registered: ‎07-11-2007

Re: Sharp dropoff on tone cap?

Bad ass, thanks amp! I saw "catalog page #677" and I thought that must be one HELL of a catalog!
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Super Contributor
mrbrown49
Posts: 17,661
Registered: ‎07-20-2006

Re: Sharp dropoff on tone cap?

Here's some helpful advice for using Mouser:

Don't "shop" on the website. They carry tens of thousands of items, and the site is not exactly set up for browsing. What it's really good for is when you already KNOW the stock numbers, and you're ready to place an order.

On the other hand, the Mouser catalog is great for browsing. It's categorized, and there's pictures of each type of component. For example, browse to the "passive components" chapter and you'll see a section for potentiometers. Open that section, and you'll see a section for Alpha components. Open that section, and you'll see a list of pages. Start at the first page in the list until you find the section for 24mm pots. Look for the picture of the pot you want, and then find it in the list with the value and taper you need. The part number is a web link to the corresponding page on the web site.

The catalog file is huge - 240MB and growing - but it's worth a download every couple of months if you're going to be ordering parts on a regular basis.


Thanks! That is very helpful.
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New Member
westmountroyal@gmail.com
Posts: 1
Registered: ‎01-24-2013

Re: Sharp dropoff on tone cap?

Aside from making sure you have the correct pot specifications, don't overlook possibility of capacitor related wire grounding out on shielding. It happened to after installing new electronics in a Les Paul. It played but sounded like shit and no power. Then after the finding and fixing the capacitor short to ground it woke up the gorrilla.

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Super Contributor
Posts: 13,279
Registered: ‎08-21-2006

Re: Sharp dropoff on tone cap?

It may be the pot type, pot value, or cap value.

If you have the amount of of trebble removal you want when you turn the pot completely down,  then you have the proper pot value. If its too muffeled, then use a lesser value or add a resistor in series with the cap.

If its a matter of going from completely off to completely muffeled quickly when you turn the pot down then you have a pot taper issue. pots have different tapers depending on their application. The overall resistance may be fine..  250K, 300K, 500K amd 1Meg are the most common used in guitars with passive pickups.

If you look at the value stamped on the pot can it should have an A, B, C, or G

In USA

  • A - Audio or Log taper
  • B - Linear taper
  • C - Reverse Log taper
  • G - Graphic taper

In Europe

  • A - Linear taper
  • B - Audio or Log taper
  • C - Reverse Log taper
  • G - Graphic taper

You can read up on audio taper types here.

http://www.geofex.com/Article_Folders/potsecrets/potscret.htm

 

Chances are what you have in the tone circuit is a linear pot which sounds abrupt when you turn it down. What is used in most guitar circuits are the logarithmic/audio tapered pots. These sound more gradual to the ear as you turn them down. The pot value for the pickup type is important too. 250K are usually used for fender single coil circuits, 300K for P90 single coils, and 500K for most Humbuckers. You can of course use different pots with different pickups but the tape may not match whats considered the normal tonal changes that occur whan the pots are turned.

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Contributor
Trinath
Posts: 39
Registered: ‎01-19-2013

Re: Sharp dropoff on tone cap?

is it still there.?
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