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Volume Control Impedance Rating

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Posted on August 12, 2014 at 07:47:40
j_barry
Audiophile

Posts: 4
Location: Kansas
Joined: January 25, 2013
 I am building a preamp that calls for a 100k volume control. I have a ladder type 50k resister based that I would like to use. Is there a way to modify it to up the rating to 100k? The ground wire is attached to a 50k resister, so I assume this is the resister that defines the input resistance. Can I just change this to a 100k resistor or does that somehow mess up the operating characteristics of the control?

 

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Here is an easier solution, posted on August 12, 2014 at 08:12:27
Chip647
Audiophile

Posts: 2649
Location: The South
Joined: December 24, 2012
 There is almost never a situation where a 50k attenuator could not replace a 100k attenuator without problems.

You can lower resistance of a pot by strapping a resistor between input and ground, increasing the resistance will have you putting a resistor in series with the pot either on the input or ground lugs of the pot. If you put the resistor in series before the input lug, you will lower the wide open signal by 3db. If you put the resistor between the ground lug and ground you will not be able to fully mute.

 

RE: Here is an easier solution, posted on August 12, 2014 at 10:55:35
Caucasian Blackplate
Industry Professional

Posts: 8313
Location: Seattle
Joined: June 18, 2004
 If there is a balance control wired in conjunction with the volume pot, then the impedance can be an issue.

 

RE: Here is an easier solution, posted on August 12, 2014 at 11:51:51
dave slagle
Manufacturer

Posts: 5430
Location: NYC
Joined: April 27, 2001
 If you put a 50K resistor on top of a 50K pot you will get attenuation from -6dB to off. If you put it in the ground leg you will only get attenuation from 0dB to -6dB

dave

 

RE: Here is an easier solution, posted on August 13, 2014 at 05:00:47
Chip647
Audiophile

Posts: 2649
Location: The South
Joined: December 24, 2012
 Even with a balance control, moving from 50K to 25K input impedance would not be noticeable in terms of losing high frequency in a typical home setup. Most passives have a 10K input impedance.

 

Use the 50K ..., posted on August 13, 2014 at 05:39:11
Naz
Audiophile

Posts: 2184
Location: Sydney
Joined: September 2, 2005
 like the guys intimated, it will most likely be slightly better than 100K. If you tell us what is driving the attenuator and what it's driving in turn we can remove any doubt.

Naz

 

RE: Volume Control Impedance Rating, posted on August 13, 2014 at 07:39:40
j_barry
Audiophile

Posts: 4
Location: Kansas
Joined: January 25, 2013
 I actually have two mono units so the balance control issue is not there. I think I will try it as is and see if it matters. If it does, then I'll modify.

Thanks for your responses.

 

RE: Here is an easier solution, posted on August 13, 2014 at 17:34:44
Caucasian Blackplate
Industry Professional

Posts: 8313
Location: Seattle
Joined: June 18, 2004
 There are some implementations (I just ran into this), where changing the impedance of the volume control can effect the overall function of the balance control in conjunction with the volume pot.

 

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