Pot Shootout: 250K vs. 500k, audio vs. linear

[Muaguana]

While the scientific explanations of how different tapers and different resistances of potentiometers affect instrument sound are interesting and informative, I feel there’s a need for a more visceral demonstration of these differences. So during my first serious mod project – changing the pots on my Squier VM fretless jazz – I decided to catalog the tonal effects of different pots via sound recordings.*

For technical details, see footnotes.

EDIT: I moved all the audio files to Soundcloud, so now you can listen on a flash player instead of downloading the files.
>>>>>>>> http://soundcloud.com/muaguana/sets/potentiometer-comparison <<<<<<<<

1-4. Tapers: Audio vs. Linear*
This will demonstrate how audio and linear tapers function in reducing signal, in both tone and volume pots. The bridge pickup is soloed for this.

5-8. Timbre: 250k vs. 500k
This will demonstrate the differences in timbre between potentiometers with 250k&#8486; and 500k&#8486; resistances. For volume, the bridge pickup is used, and is thus soloed.

9-10. Timbre: 250k vs. 500k
These last two feature both pickups at full, and all three pots bearing the same resistance rating.

So there ya go. It's not perfect, and I'm certainly not saying every bass and wiring configuration will change the same way. But I hope it'll help give less experienced technicians (like myself) an idea of how pot parameters manifest themselves in an instrument's sound. Or do they at all? I'll let your ears be the judge.

__________________________________________________
*For these recordings, I used the aforementioned Squier VM fretless with the stock Duncan Designed J pickups, strung with the (now-boiled) light gauge roundwounds GC had put on it, which were given a once-over with GHS FastFret prior to each recording. I used the .047µf capacitor that came with the guitar on all tone pots. I recorded through an Mbox2 Pro via DI (no preamp or pedals) into Pro Tools LE 8 at a sample rate of 48kHz, at the same gain setting throughout. No compression or EQ was used.
Edit: When I re-did the volume pot tapers, I had my bass equipped with D-Addario medium-gauge chromes, a Tesla VR-B4 pickup in the bridge position, and an SD Bassline SJB-2 in the neck.

*Since I don&#8217;t know how to measure the amount a potentiometer is turned (that is, don&#8217;t know the unit of measurement), here&#8217;s how I originally did it: I set a click track to 108bpm, hit an open note on a beat, and started turning down the knob on the third beat, turning it to 0 over the next 6 beats, then I brought it back up to 100% in 4 beats. Three measures of 4/4. Recently I uploaded new files for the volume pot tapers (my tone pot is acting up, so I'll have to do that later.) See my post below for details.

 

[Stephen]

Great work !!!

 

[walterw]

also, the 500k linear volume example starts out quieter than the 500k audio volume example.

still, i totally hear the audio volume dropping off fast while the linear volume smoothly reduces (assuming you turned both knobs down at the same rate).

if you have the energy to try it again, record the volume taper tests by turning down the knob while continuously plucking the string, so the string's own decay doesn't mask the taper.

 

[Muaguana]

also, the 500k linear volume example starts out quieter than the 500k audio volume example.

still, i totally hear the audio volume dropping off fast while the linear volume smoothly reduces (assuming you turned both knobs down at the same rate).

if you have the energy to try it again, record the volume taper tests by turning down the knob while continuously plucking the string, so the string's own decay doesn't mask the taper.

Yeah, I figured I'd need to re-do the taper portion. I think my dynamics were different when plucking the note, also like you said the decay was masking the taper affect. Thanks for the suggestion; I'll definitely try that next time.

I may have to get (or build) some mechanical device to turn the knob automatically at a set rate. That would be far more accurate for the purposes of this discussion. Anyone got ideas for that?

Great work !!! However, really hard to download from that site. I gave up after finally getting a few to download.

I know, sorry about that. On that subject, does anyone know a good site to share files like that with? Or host them so I can just post a link to a flash player?

 

[Stephen]

I tried to download again later and it worked more smoothly.

I have had success with Link Removed

Again, thanks for your work.

 

[FunkMetalBass]

Soundcloud

Also, I suspect an eBow would be the most efficient way of keeping the note consistent. Turning the knob up and down, however, was probably best achieved in the way you did it.

 

[walterw]

I may have to get (or build) some mechanical device to turn the knob automatically at a set rate. That would be far more accurate for the purposes of this discussion. Anyone got ideas for that?

fergit all that mess! just record several seconds of constantly plucking a string while turning each volume up and then down a few times as evenly as you can.

or, slap a knob on there with numbers, then just pluck a string at 10, then 8, then 6, etc. (the more i think about it, this will be the most useful demo.)

either way, by having multiple volume twists in one take, we can sort of "average out" the slight differences and get a good feel for how it behaves.

 

[line6man]

But which pot is best for metal?

 

[Muaguana]

I tried to download again later and it worked more smoothly.

I have had success with Link Removed
Again, thanks for your work.

Thank you for the encouragement and suggestion.

Also, I suspect an eBow would be the most efficient way of keeping the note consistent.

Huh, I didn't even know those things existed. Pretty nifty; I'd like to get one just to screw around with (if I had the money.)

either way, by having multiple volume twists in one take, we can sort of "average out" the slight differences and get a good feel for how it behaves.

Very true; that crossed my mind at one point but for some reason decided not to do it. Makes perfect sense, though.

But which pot is best for metal?

TO THE BC RICH MOBILE!

 

[FunkMetalBass]

But which pot is best for metal?

The answer is: no pot. No pot = max volume = totally metuhl!!!

 

[Muaguana]

So, after four or so hours of trial-and-error (as well as filing a paperclip into a needle to unclog a super glue tube,) I finally devised a way to more accurately measure tapers (or at least conceptualize their differences in a relativistic sense.) Behold!

... long story. Anyway, I just replaced the volume taper files on Soundcloud with recordings that are longer, more in-depth, and more accurate. Instead of trying to evenly roll off the knob, which is impossible anyway considering I'm a human with hand tremors, I hijaked one of the knobs from my sister's old strat (don't worry, it's a Squier) and super-glued it to a Radio Shack knob, since it wouldn't fit on the pots. I marked on my pickguard where the pot stops at full, and used it as a sort of meter to help better quantify the change in potentiometer position.

In the audio files, I drone quarter notes at 108bpm while manipulating the volume; there are three takes of each pattern so you can sort of average out the human errors. First pattern decreases then increases the volume knob by one number every two beats. Second decreases/increases the volume knob by one number every beat. Third decreases/increases it by 2 numbers every 2 beats (10, 8, 6, 4, 2, 1/0, 2, etc.). Fourth decreases/increases the volume by 2 numbers every beat.

Hopefully this will give people a better idea of how these tapers affect volume. I know the examples I originally posted were crap, so hopefully this makes up for it. Also, I didn't do the tone pot because a) mine is having disagreements with life, and b) the choice of taper isn't nearly as contested as volume pots. I've never heard anyone argue over which taper to use in a tone pot; everyone says audio. I may update it later if I have spare time, though, just for kicks.

 

[pumatheman]

I really like the harmonic rich tone of the 500k pot vols and 250k pot tone...I think I'll go for this plus 0,1 cap orange drop in order to get a wider freq range on my sound
GREAT JOB!

 

[Muaguana]

I really like the harmonic rich tone of the 500k pot vols and 250k pot tone...I think I'll go for this plus 0,1 cap orange drop in order to get a wider freq range on my sound
GREAT JOB!

Thanks, I'm glad it was helpful.

 

[Gort]

I really like the harmonic rich tone of the 500k pot vols and 250k pot tone...

That's my favorite too.

 

[cassius987]

In Denver we have a pot critic who has done many a pot shootout.

 

[pumatheman]

I've a PJ passive fretless (aria igb-40, ceramic PUs) it has 2 vol pots of 500k and tone pot of 250k (w/green drop cap no stamp it could be on 0,047). With this bass there is a more efficent gradual attenuation, the tone blends darker in a more proportional way than of my jazz bass (fender mim with custom shop 60 PUs)with 2 vol pots and one tone pot all of 250k (w/orange drop cap of 0.1) where the tone pot is more like an interructor.

@Muaguana, do you have noticed a more efficent tone gradual attenuation with configuration: vol post of 500k, tone pot of 250k?

 

[Muaguana]

I've a PJ passive fretless (aria igb-40, ceramic PUs) it has 2 vol pots of 500k and tone pot of 250k (w/green drop cap no stamp it could be on 0,047). With this bass there is a more efficent gradual attenuation, the tone blends darker in a more proportional way than of my jazz bass (fender mim with custom shop 60 PUs)with 2 vol pots and one tone pot all of 250k (w/orange drop cap of 0.1) where the tone pot is more like an interructor.

@Muaguana, do you have noticed a more efficent tone gradual attenuation with configuration: vol post of 500k, tone pot of 250k?

I have that configuration installed right now, actually. I haven't done an objective comparison yet, but I'm happy with it. I didn't notice any deficiency in taper when the bass was 250k across the board, but that was a while ago and I have a terrible memory. The discrepancy between your basses might be due more to cap value than pot value, as a change in volume pots shouldn't drastically change how the tone control functions.

Edit: There's been posts in other threads about the loading effects of using higher-valued pots in passive basses - i.e., tone is lost when rolling volume knobs down. If this is an issue to you, put in a treble bleed circuit on each pot; below is the diagram I followed, though I used .001 caps because that's what Radio Shack had in stock.

 

[Muaguana]

In Denver we have a pot critic who has done many a pot shootout.

Finally someone makes a narcotic joke. I was waiting for that one for four months.

 

[bassix]

I just found your thread. Sorry I'm a bit late to the game.

I'm confused by the 5-8 Timbre thread in that, while they're all labeled as bridge pickup only, #6 sounds completely different from that other 3 - and sounds very much like the last two samples - where both pickups are full on. Is it possible #6 is both pickups on? I can't imagine simply changing the volume pot from a 250k to a 500k - all else remaining the same - would result in THAT big of a difference. Additionally, 5, 7, & 8 all have that soloed bridge midrange quality, while #6 doesn't.

Thanks!

 

[SouthportJim]

Thanks so much...this really helped my 'pre-upgrade' research!
;-)