Quick (maybe) question on pots and resistance

CrashHardtop

Joined: Jun 14, 2012
Posts: 152
Meridian, Idaho
United States

Posted on Dec 15 2014 04:46 PM

If you wire a 500K ohm resistor in parallel with a 500K ohm pot will that result in good sounding 250K ohm equivalent pot?

—

More cowbell?? Nah...More Reverb!!

Top

dboomer

Joined: Jan 05, 2009
Posts: 262
Port Hueneme, CA
1 POTD Pin

Posted on Dec 15 2014 06:55 PM

Well it would result in 250kOhms resistance. But "good sounding" depends on your definition. I would think it would be difficult to work with from a mechanical standpoint.

Top

eddiekatcher

Joined: Mar 14, 2006
Posts: 2775
Atlanta, GA
1 News Pin

Posted on Dec 15 2014 07:08 PM

If your plan is to end up with the total load across the pickup of 250K it will do that. It should work fine. You can use a 1/4 watt resister to save space. 1/8 watt will do but is a bit more delicate for we ham fisted guitar hacks.

The nice part is if you end up not liking it, simply snip the resistor out. No need to fiddle with your soldering iron.

I bridge my 1 megs with a 1 meg resistor to get 500k and it works fine. It seems to maintain a reasonable response curve.

ed

—

Traditional........speak softly and play through a big blonde amp. Did I mention that I still like big blonde amps?

Top

JObeast

Joined: Jul 24, 2012
Posts: 2762
Finknabad, Squinkistan
Turkmenistan

Posted on Dec 16 2014 12:24 AM

What is the proper resisitor for a TOne pot of 500 K ohm value? I have this 'chicklet' thing which I think is valued at .437mF... maybe not?

—

Squink Out!

Top

CrashHardtop

Joined: Jun 14, 2012
Posts: 152
Meridian, Idaho
United States

Posted on Dec 16 2014 10:00 AM

JObeast, I'll apply my (extrememly) limited knowledge of electronics here. The chiclet you describe is a capacitor--the "mF" gives it away every time. I will leave it to those more knowledgeable than I to describe its function. If you parallel connect two resistors of equal value the total resistance will be half of the combined values. As Eddie pointed out, running a 1M resistor in parallel with a 1M pot yields 500K of total resitance.

BTW, if you run resistors in series the resistance is cumulative. And if you have two resistors of different values in parallel, the total resistance will be less than the value of the lower-value resistor.

Lastly, thanks to Eddie for your reply. Exactly what I was looking for.

—

More cowbell?? Nah...More Reverb!!

Top

JObeast

Joined: Jul 24, 2012
Posts: 2762
Finknabad, Squinkistan
Turkmenistan

Posted on Dec 16 2014 01:36 PM

D'oh! Thanks Crash, that's what it does, it capacitates, doesn't resist!

—

Squink Out!

Top

eddiekatcher

Joined: Mar 14, 2006
Posts: 2775
Atlanta, GA
1 News Pin

Posted on Dec 16 2014 05:15 PM

Ssssssssssh it actually passes higher frequencies easier than lower frequencies. (high pass filter)

The higher the cap value the more the lows sneak through.

ed

—

Traditional........speak softly and play through a big blonde amp. Did I mention that I still like big blonde amps?

Top

Badger

Joined: Nov 16, 2013
Posts: 4536
Wisconsin
United States

Posted on Dec 16 2014 05:25 PM

eddiekatcher wrote:

Ssssssssssh it actually passes higher frequencies easier than lower frequencies. (high pass filter)

The higher the cap value the more the lows sneak through.

ed

There you go again, talking in plain English.

—

Wes
SoCal ex-pat with a snow shovel

DISCLAIMER: The above is opinion/suggestion only & should not be used for mission planning/navigation, tweaking of instruments, beverage selection, or wardrobe choices.

Top

BJB

Joined: Jul 28, 2008
Posts: 413
United States

Posted on Dec 18 2014 05:06 AM

Hey, I finally figured out what a '.437' uF capacitor is! That's a very non-standard value so I had no idea how that could get into a guitar. But it turns out that caps printed with 473 do exist. That three-digit number is an EIA code for the value. It's sort of like the resistor color code but with numbers instead of colors. The capacitor code is a harder to deal with than the resistor color code because it gives you picofarads and then you have to convert to microfarads. Personally, I don't bother with the conversion and I use a table of values instead:

The table shows a 473 as being a .047 microfarad capacitor. Sorry for the digression but I'm happy that this mystery is solved!

—

If it ain't broke, fix it until it is.

Top

dboomer

Joined: Jan 05, 2009
Posts: 262
Port Hueneme, CA
1 POTD Pin

Posted on Dec 18 2014 12:14 PM

"47" is the value and "3" is the multiplier. Multiply uF times 1,000,000 to get pF.

Top

BJB

Joined: Jul 28, 2008
Posts: 413
United States

Posted on Dec 19 2014 05:49 PM

47 is the value and 3 is the multiplier, but the result is in pF, not uF. So we have 47000 pF, then divide by a million (move the decimal point six places to the left) to get 0.047 uF.

This is too much thinking for me so I have a small table taped to the side of my oscilloscope.

—

If it ain't broke, fix it until it is.

Top

JObeast

Joined: Jul 24, 2012
Posts: 2762
Finknabad, Squinkistan
Turkmenistan

Posted on Dec 19 2014 11:06 PM

Thanks, B, fo rthe chart. I intuited that the value has something to do with guitar parts. So is it the right capacitance for 500k ohm pots and mid-level output p'ups?
BJB wrote:

47 is the value and 3 is the multiplier, but the result is in pF, not uF. So we have 47000 pF, then divide by a million (move the decimal point six places to the left) to get 0.047 uF.

This is too much thinking for me so I have a small table taped to the side of my oscilloscope.

—

Squink Out!

Top

CrashHardtop Joined: Jun 14, 2012 Posts: 152 Meridian, Idaho	Posted on Dec 15 2014 04:46 PM If you wire a 500K ohm resistor in parallel with a 500K ohm pot will that result in good sounding 250K ohm equivalent pot? — More cowbell?? Nah...More Reverb!! Top
dboomer Joined: Jan 05, 2009 Posts: 262 Port Hueneme, CA	Posted on Dec 15 2014 06:55 PM Well it would result in 250kOhms resistance. But "good sounding" depends on your definition. I would think it would be difficult to work with from a mechanical standpoint. Top
eddiekatcher Joined: Mar 14, 2006 Posts: 2775 Atlanta, GA	Posted on Dec 15 2014 07:08 PM If your plan is to end up with the total load across the pickup of 250K it will do that. It should work fine. You can use a 1/4 watt resister to save space. 1/8 watt will do but is a bit more delicate for we ham fisted guitar hacks. The nice part is if you end up not liking it, simply snip the resistor out. No need to fiddle with your soldering iron. I bridge my 1 megs with a 1 meg resistor to get 500k and it works fine. It seems to maintain a reasonable response curve. ed — Traditional........speak softly and play through a big blonde amp. Did I mention that I still like big blonde amps? Top
JObeast Joined: Jul 24, 2012 Posts: 2762 Finknabad, Squinkistan	Posted on Dec 16 2014 12:24 AM What is the proper resisitor for a TOne pot of 500 K ohm value? I have this 'chicklet' thing which I think is valued at .437mF... maybe not? — Squink Out! Top
CrashHardtop Joined: Jun 14, 2012 Posts: 152 Meridian, Idaho	Posted on Dec 16 2014 10:00 AM JObeast, I'll apply my (extrememly) limited knowledge of electronics here. The chiclet you describe is a capacitor--the "mF" gives it away every time. I will leave it to those more knowledgeable than I to describe its function. If you parallel connect two resistors of equal value the total resistance will be half of the combined values. As Eddie pointed out, running a 1M resistor in parallel with a 1M pot yields 500K of total resitance. BTW, if you run resistors in series the resistance is cumulative. And if you have two resistors of different values in parallel, the total resistance will be less than the value of the lower-value resistor. Lastly, thanks to Eddie for your reply. Exactly what I was looking for. — More cowbell?? Nah...More Reverb!! Top
JObeast Joined: Jul 24, 2012 Posts: 2762 Finknabad, Squinkistan	Posted on Dec 16 2014 01:36 PM D'oh! Thanks Crash, that's what it does, it capacitates, doesn't resist! — Squink Out! Top
eddiekatcher Joined: Mar 14, 2006 Posts: 2775 Atlanta, GA	Posted on Dec 16 2014 05:15 PM Ssssssssssh it actually passes higher frequencies easier than lower frequencies. (high pass filter) The higher the cap value the more the lows sneak through. ed — Traditional........speak softly and play through a big blonde amp. Did I mention that I still like big blonde amps? Top
Badger Joined: Nov 16, 2013 Posts: 4536 Wisconsin	Posted on Dec 16 2014 05:25 PM eddiekatcher wrote: Ssssssssssh it actually passes higher frequencies easier than lower frequencies. (high pass filter) The higher the cap value the more the lows sneak through. ed There you go again, talking in plain English. — Wes SoCal ex-pat with a snow shovel DISCLAIMER: The above is opinion/suggestion only & should not be used for mission planning/navigation, tweaking of instruments, beverage selection, or wardrobe choices. Top
BJB Joined: Jul 28, 2008 Posts: 413	Posted on Dec 18 2014 05:06 AM Hey, I finally figured out what a '.437' uF capacitor is! That's a very non-standard value so I had no idea how that could get into a guitar. But it turns out that caps printed with 473 do exist. That three-digit number is an EIA code for the value. It's sort of like the resistor color code but with numbers instead of colors. The capacitor code is a harder to deal with than the resistor color code because it gives you picofarads and then you have to convert to microfarads. Personally, I don't bother with the conversion and I use a table of values instead: The table shows a 473 as being a .047 microfarad capacitor. Sorry for the digression but I'm happy that this mystery is solved! — If it ain't broke, fix it until it is. Top
dboomer Joined: Jan 05, 2009 Posts: 262 Port Hueneme, CA	Posted on Dec 18 2014 12:14 PM "47" is the value and "3" is the multiplier. Multiply uF times 1,000,000 to get pF. Top
BJB Joined: Jul 28, 2008 Posts: 413	Posted on Dec 19 2014 05:49 PM 47 is the value and 3 is the multiplier, but the result is in pF, not uF. So we have 47000 pF, then divide by a million (move the decimal point six places to the left) to get 0.047 uF. This is too much thinking for me so I have a small table taped to the side of my oscilloscope. — If it ain't broke, fix it until it is. Top
JObeast Joined: Jul 24, 2012 Posts: 2762 Finknabad, Squinkistan	Posted on Dec 19 2014 11:06 PM Thanks, B, fo rthe chart. I intuited that the value has something to do with guitar parts. So is it the right capacitance for 500k ohm pots and mid-level output p'ups? BJB wrote: 47 is the value and 3 is the multiplier, but the result is in pF, not uF. So we have 47000 pF, then divide by a million (move the decimal point six places to the left) to get 0.047 uF. This is too much thinking for me so I have a small table taped to the side of my oscilloscope. — Squink Out! Top

SurfGuitar101 Forums » Gear »

Quick (maybe) question on pots and resistance