Identify Audio Taper Potentiometers

RussellW · 25th May 2010, 08:14 PM

I have some 50k ohm audio slide pots and I don't know which end to ground.
Can someone tell me about audio taper pots? If I put the slider in the center then what should the resistance be from center to ground and the resistance from center to the audio input terminal?
Is there a better way to determine the taper of a pot and identify the terminals?

Thanks,
Russell Williams

richie00boy · 25th May 2010, 08:20 PM

Turn it fully anti-clockwise. The two pins measuring very low resistance are the wiper and ground.

RussellW · 25th May 2010, 08:22 PM

Oops! Slide pots don't have a counter-clockwise.

RussellW

MoodySteve · 25th May 2010, 08:49 PM

If you put the slider exactly in the center, you should measure about 25kΩ between the 'center' (wiper) and ends (legs) if it's linear taper. I think that most slide pots have a linear taper.

If you measure significantly less (probably around 2kΩ) or more (probably around 45kΩ) than 25kΩ, then you probably have an audio taper (log taper) pot. Which one of those you measure depends on which 'leg' you use as reference.

RussellW · 25th May 2010, 09:22 PM

If I put the slider in the center then I measure (very roughly) 10k ohms to one terminal (to the slider) and 40k ohms to the other terminal. Which terminal should be grounded and which should be audio input?

Thank-you all for your help.
Russell W.

Don Hills · 25th May 2010, 09:32 PM

The 40K ohms end should be grounded. Resistance changes more rapidly at the "grounded" end of the pot, because of the log resistance law. (Actually, most "log" pots are just two different linear resistance tapers connected at about 1/3 up from the "ground" end.)

RussellW · 25th May 2010, 09:55 PM

Thank-you very much, Don Hills.
That is very interesting.
I had a slide rule once (log log decitrig) and I noticed that 3 was close to the middle.
Relating the audio curve of the ear's sensitivity to a log scale is mind boggling to me.
Thank-you so much for the help.
Russell Williams

25th May 2010, 08:14 PM	#1
RussellW diyAudio Member Join Date: Apr 2009	Identify Audio Taper Potentiometers I have some 50k ohm audio slide pots and I don't know which end to ground. Can someone tell me about audio taper pots? If I put the slider in the center then what should the resistance be from center to ground and the resistance from center to the audio input terminal? Is there a better way to determine the taper of a pot and identify the terminals? Thanks, Russell Williams

25th May 2010, 08:20 PM	#2
richie00boy Did it Himself diyAudio Member Join Date: Nov 2003 Location: Gloucestershire, England, UK	Turn it fully anti-clockwise. The two pins measuring very low resistance are the wiper and ground. __________________ www.readresearch.co.uk my website for UK diy audio people - designs, PCBs, kits and more

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25th May 2010, 08:22 PM	#3
RussellW diyAudio Member Join Date: Apr 2009	Oops! Slide pots don't have a counter-clockwise. RussellW

25th May 2010, 08:49 PM	#4
MoodySteve diyAudio Member Join Date: Apr 2007	If you put the slider exactly in the center, you should measure about 25kΩ between the 'center' (wiper) and ends (legs) if it's linear taper. I think that most slide pots have a linear taper. If you measure significantly less (probably around 2kΩ) or more (probably around 45kΩ) than 25kΩ, then you probably have an audio taper (log taper) pot. Which one of those you measure depends on which 'leg' you use as reference.

25th May 2010, 09:22 PM	#5
RussellW diyAudio Member Join Date: Apr 2009	If I put the slider in the center then I measure (very roughly) 10k ohms to one terminal (to the slider) and 40k ohms to the other terminal. Which terminal should be grounded and which should be audio input? Thank-you all for your help. Russell W.

25th May 2010, 09:32 PM	#6
Don Hills diyAudio Member Join Date: May 2009 Location: Wellington	The 40K ohms end should be grounded. Resistance changes more rapidly at the "grounded" end of the pot, because of the log resistance law. (Actually, most "log" pots are just two different linear resistance tapers connected at about 1/3 up from the "ground" end.)

25th May 2010, 09:55 PM	#7
RussellW diyAudio Member Join Date: Apr 2009	Thank-you very much, Don Hills. That is very interesting. I had a slide rule once (log log decitrig) and I noticed that 3 was close to the middle. Relating the audio curve of the ear's sensitivity to a log scale is mind boggling to me. Thank-you so much for the help. Russell Williams

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