When to use an Audio VS Linear pot?

[Rain Dog]

First is just the general question. What is the rule of thumb for deciding which potentiometer to use in a circuit?

Second is specific. I'm building a GGG's Big Muff Pi for my bass. I want to reduce the voltage at the input of the circuit and do it at the pedal. I want to do this without turning down the volume on my bass. There is a short explanation for that but I won't tell you unless you ask.

I have very high output passive pickups on my bass and with the pickups full on it drives the circuit way harder than I want. I assume it would be an Audio/Logarithmic potentiometer. It that correct?

[petemoore]

The  EZ with input gain control.
 I think audio is what you want for that.
 The vol control on the guitar does the same thing.
 Alternately try fixed resistor values [+/-...10k-68kin series with the signal at the input.
 The pot method of input reduction is nice, like a third gain control [the guitar vol. and the BMP gain being the 1rst and 2nd], so you can set the max input level to be lower enough so that you can whip the guitar vol to max. and have that take you to 'max gain' [whatever you set the 'extra pot' as], as you've preset it with the input gain control.
 In general, the schematics will mark A or B log by the pot, A is for Audio B is for linear taper...
 Vol pots are 'usually audio taper.

[Mark Hammer]

Not your fault, but this has to be about the 6th time this year I've had to say this.

1) If it has to do with "loudness", you need log/audio.

2) If having an identifiable "middle" is useful, then linear is needed (prototypic case is a boost/cut tone control, or a blend control).

3) Log and linear will always "work" in circuits, but for any given function and user, one may deliver more degrees of usable rotation and ability to fine tune tune or dial in than the other.  Example, if all the meaningful changes in degree of fuzz are crowded into the last 10 degrees of rotation of a pot, it becomes hard to easily and precisely dial in what you want.  Switching to the other taper might help matters.

[Rain Dog]

Not your fault, but this has to be about the 6th time this year I've had to say this.

1) If it has to do with "loudness", you need log/audio.

2) If having an identifiable "middle" is useful, then linear is needed (prototypic case is a boost/cut tone control, or a blend control).

3) Log and linear will always "work" in circuits, but for any given function and user, one may deliver more degrees of usable rotation and ability to fine tune tune or dial in than the other.  Example, if all the meaningful changes in degree of fuzz are crowded into the last 10 degrees of rotation of a pot, it becomes hard to easily and precisely dial in what you want.  Switching to the other taper might help matters.

Sorry about that. Guess I need to spend more time in the DIY FAQ section. Thanks for the replys.

[Mark Hammer]

Seriously...NOT....YOUR....FAULT.  I'm certain there are plenty of things that beginners simply do not realize ought to exist in the archives or as an FAQ somewhere.  My sigh is not directed at you.  Simply a recognition of how lovely it would be if there was a foolproof way to easily connect beginners with the key information they regularly desire and need.  No need to apologize for needing to know the same stuff as the rest of us.

[Rain Dog]

Seriously...NOT....YOUR....FAULT.  I'm certain there are plenty of things that beginners simply do not realize ought to exist in the archives or as an FAQ somewhere.  My sigh is not directed at you.  Simply a recognition of how lovely it would be if there was a foolproof way to easily connect beginners with the key information they regularly desire and need.  No need to apologize for needing to know the same stuff as the rest of us.

You can lead a techie to a web site but you can't force them to think!  

[R.G.]

I'm reminded of the story about a master sergeant in the US Army who was posted to an army induction center.

As you can imagine, every new batch of recruits got the same things wrong, every time, like clockwork. After one batch of recruits too many, the master sergeant let out a bellow "You #@#% idiots!! You come in here every day and get the same things wrong!! Don't you ever @#$^$#^ listen???"

The one I love is the continual tide of people who are "designing" some or other effect, and want to know a question that's answered by Ohm's law.

[Ben N]

Ohm's Law???

:lol:  :lol:  :lol:

[Mark Hammer]

Yeah, don't you know "Om's Law"?  It's one of the summer replacement series on FOX TV about this former Buddhist monk who goes to work for the LAPD in the anti-gang squad.  Looks pretty good from the promos I've seen, with David Allen Grier as a wisecracking police lieutenant, Pam Grier as the police psychologist who's seen it all before, Rosey Grier as the local streetwise Baptist minister who runs youth outreach programs out of a storefront, and Germaine Greer as the grandmother who raised the lead character when he was orphaned.  The only thing I'm skeptical about is casting George Huff in the lead role.  I mean he has all this recognition-factor thing going for him as a result of American Idol, and he's certainly likeable, and the one-song-per-episode thing provides a nice twist, but I wonder whether he'll be believable in the lead role.  On the other hand, it IS just a summer replacement.

[Hal]

Mark - that sounds AWESOME!  TV needs more quality programming like this.   Any idea when it premiers?   But i think they were talking about Ohm's law, not Om's law....