need a pot value for a small project

xistenz

xistenz

New member
i'm going to be building a small monitor switchbox/passive volume controller for my DAW this weekend. i have everything else sketched out, but i'm not really sure what value pot i should use for the volume knob. my gut tells me 10k will work, but i'm not sure. this is for line levels out of my soundcard into powered monitors that have input impedence of 20k.
 
Harvey Gerst said:
200K to 1 megohm pot should work nicely.
Click to expand...

I thought any size of pot would work? It's just a potential divider, you can half a voltage with 2x 47R resistors & 2x 1M resistors will do the same?
 
orson198305 said:
I thought any size of pot would work? It's just a potential divider, you can half a voltage with 2x 47R resistors & 2x 1M resistors will do the same?
Click to expand...
Maybe I misread it. I thought he wanted a volume control. If the pot resistance is too low, he could load down the source pretty easy. I think this is what he needs:
 
Last edited:
Harvey Gerst said:
Maybe I misread it. I thought he wanted a volume control. If the pot resistance is too low, he could load down the source pretty easy. I think this is what he needs:
Click to expand...

No, no your right, i was asking a Q :)
 
orson198305 said:
No, no your right, i was asking a Q :)
Click to expand...
Since I haven't a clue as to how either circuit (sound card or speaker input) is designed, and what they really wanna see as far as loads, this would be the simplest solution without loading either one. The sound card wouldn't see any load (with a hi-z pot), and the speaker could pull off any voltage it needed. In full off position, the speaker input is shorted to prevent stray hum and noise.

Not exactly pretty, but it should work fine.
 
i ended up using a cheapo 50k because that's all the store had. two problems; it doesn't track evenly, and the resistance isn't sufficient. even tracking is desirable because at lower volumes one side is audibly higher than the other. higher resistance is needed to make the knob less sensitive at lower volumes; i.e. the slightest movement causes big jumps in volume at low volumes. a higher value pot will even that out.

i'm looking into an alps blue velvet 200k dual, just trying to find a place that sells them. ebay might be a good source. just have to be patient.

but otherwise the knob works! no more screwing around with the little software mixer app every time i need to adjust the volume on my monitors :D
 
I think you will want a 1 meg dual (stereo) audio taper pot...anytime you use two seperate pots the tracking will be off and a linear taper is a little wierd for volume control in an audio setup...Ratshack won't have it..try mouser.com or digikey.com..audio (or log) taper...reverse log taper if you can find it (good luck on that one :)...

60 beans an oz? I think I am moving to your town!!!! ;)

Ray
 
yep, i know, i grabbed the cheapo because it's all they had at the time and i figured i could get the whole thing put together while i found a good one in the 200k to 1M range.

the alps blue velvet series are dual log taper conductive plastic pots. they are what a lot of hifi diy folks like to use, aside from stepped attenuators which are another option. all the mouser pots that are worth buying (alps, bourne) have obscene minimum quantities. the only ones they sell individually are taiwaan crap jobs. digikey has nothing worth buying.
 
I was just thinking...$60 an ounce has never been seen by me...when I was a teen and knew such things it was like $60 a quarter... :cool:

War
 
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