linear vs audio pot

[fixr1984]

Ive seen schematics refer to diferent pots as linear and some as audio. Is there a huge diference or can you put an audio pot where a linear is called for? If so could you swap out a 1k linear to a 100k audio? I hope this isnt a dumb question. I did a search and couldnt find out if anyone else had asked it.

[nelson]

I could explain it to you, however it would be a waste of time and not nearly as eloquent or knowledgable as this


http://www.geofex.com/Article_Folders/potsecrets/potscret.htm

[fixr1984]

That was what I was looking for. Thanks for the info.

[JimRayden]

As soon as I saw the thread topic, this article suddenly popped into my head. But you beat me to it, Nelson. 


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Jimbo

[Mark Hammer]

If it is volume of any kind, it always need log.  If it is important to identify the "middle" in some way (e.g., blend control, cut/boost tone control), then linear is required.  Beyond that, choice of taper will often depend on your tastes and needs.  What taper does is "distribute" the adjustability of the control across the entire rotation in a certain way.  For a given type of control (e.g., distortion amount), some players may be far more interested in fine adjustment of subtle shades of distortion, and others may be far more interested is small differences between extreme degrees of fuzz.  Obviously the same taper will not make both of them equally happy.

Whatever the case, taper will have no bearing on whether the circuit *works* or not.  If the schem says log and you only have linear sitting around, use the linear, see if you like it, and order a log one if the taper seems to stand a reasonable degree of improving things according to your needs.

[R.G.]

Dead rignt, Mark. Get **something** in there and working and get the perfect part when you can.

[Fp-www.Tonepad.com]

If it is volume of any kind, it always need log.

Not always. The example I have experience with is the inverting input of an opamp. Depending on the values of the surrounding resistors, a voltage divider configured volume pot can have a logaritmic response for gain when the pot is linear. Check out the Tube Screamer volume pot for example (look at the volume pot as two resistors) also, check out the Rebote2.5 delay wet volume pot. For the Rebote2.5 the change in the pot was simulated to pick the value of the pot that having linear taper would give logaritmic gain change.

Fp

[fixr1984]

Ive got about 15 pots lying around that my father in law gave me. I have no clue what they are, im guessing they are volume pots but i cant be sure. Is there a way of looking at them or a way that an ohm meter reads them that will tell you?

[Fp-www.Tonepad.com]

Read this:
http://www.geofex.com/Article_Folders/potsecrets/potscret.htm

Fp

[fixr1984]

How about this question? Ive heard that if you replace the 500k volume pot in your guitar with a 1 meg pot you will have more volume. Is that true? If thats the case and you replace a 100k volume in an effect to a 500k, will you get more volume? On that same train of thought...if i took the 1k linear from the fuzz control of my fuzz face clone and changed it to say a 10k, will i get more of the fuzz effect? To me it seems that if you go up in the pot resistance you should lose volume but with most things electronic i seem to be thinking backwards. Sorry if these questions have already been asked.

[Hal]

very different, and much more complicated.

That has to do with impedance and loading and all sorts of other things...And I cant explain it, I dont think I even understand well.

[JimRayden]

How about this question? Ive heard that if you replace the 500k volume pot in your guitar with a 1 meg pot you will have more volume. Is that true? If thats the case and you replace a 100k volume in an effect to a 500k, will you get more volume? On that same train of thought...if i took the 1k linear from the fuzz control of my fuzz face clone and changed it to say a 10k, will i get more of the fuzz effect? To me it seems that if you go up in the pot resistance you should lose volume but with most things electronic i seem to be thinking backwards. Sorry if these questions have already been asked.

Oh well, why don't we all just slap a 10000Meg pots into our guitars and play directly into a loudspeaker? 

As Hal stated, it's far more complicated than that. Too bad I can't point at a certain article for you to read though.

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Jimbo

[Paul Perry (Frostwave)]

What volume pot to use? Think of it this way: the guitar pickup behves as though it is a signal source (voltage) in series with an impedance (let's just call it a resistance here). Now when this goes to the pot, the resitance of the pickup& the resistance of the pot are in series, and act as a divider. So you might think, why not make the pot as big as possible, because then there is minimum loss?
Well, let's make it say 100Meg... now when the pot is set half way, you have 50meg in series with your input signal!! and if the stompbox you are feeding the signal to is only 1Meg (it could be less!) then by the same reasoning there goes 98% of your signal!!
So as a general rule, let's have the pot around what the pickup impedance is, and let's ahve a high input impednce for the effect.

[Fp-www.Tonepad.com]

So as a general rule, let's have the pot around what the pickup impedance is, and let's ahve a high input impednce for the effect.

Pickup DC resistance goes from ~6kohm for a cold single coil to ~20kohm for a hot humbucker, and the 'standard' pot values go from 250k for single coils and 500k for humbuckers. These numbers are from memory and I could be wrong. Am I or are you talking about something else?

Fp

[Mark Hammer]

How about this question? Ive heard that if you replace the 500k volume pot in your guitar with a 1 meg pot you will have more volume. Is that true? If thats the case and you replace a 100k volume in an effect to a 500k, will you get more volume?

Important to distinguish between actual volume and perceived volume.  Reinstating high end that may have been lost through the loading of lower-value volume pots can appear to increase volume, simply because there is more presence to the sound.  Muffled = seems softer.  Bright = seems louder.

Of course, as has been mentioned, all of this pertains to when the volume pot behaves very much like a fixed resistance to ground (i.e., up full or very near).  Once the pot starts to be turned down from max, and all that resistance is added in series with the pickup, the rules change.

[fixr1984]

Baiscaly just stick to the schematic and let the experts tell me what to use..