Uproar potentiometers

[Megadeth]

Hi so im currently building the uproar and i have a question regarding the potentiometers used.

The bill of material states that a 10k C potentiometer is being used, and that kinda throws me off the goat since that is the old way of marking them right?

In the bill of materials there is B, C and A specified and that kinda mixes up the "old" and the "new" way of marking them or should i consider the A potentiometer in this case as an Antilog?.

Please help me im so confused.

The pots used is GAIN 100kB, TONE 10kC, VOL 10kA


/Mega

[jimilee]

Hi so im currently building the uproar and i have a question regarding the potentiometers used.

The bill of material states that a 10k C potentiometer is being used, and that kinda throws me off the goat since that is the old way of marking them right?

In the bill of materials there is B, C and A specified and that kinda mixes up the "old" and the "new" way of marking them or should i consider the A potentiometer in this case as an Antilog?.

Please help me im so confused.

The pots used is GAIN 100kB, TONE 10kC, VOL 10kA


/Mega

Yeah so you're looking at 100kb=linear 10kC=reverse audio 10kA=audio....Different places mark them differently,for example mammoth marks them anti log, log and linear...everyone else seems to follow suit with adio, linear and reverse audio.

[Megadeth]

Thanks alot!

Im not the greatest when it comes to pots, but cant i simply reverse a 10k A pot to work as a 10k C?

//Mega

[jimilee]

yep

[Megadeth]

Thanks alot bud!

[alexradium]

Thanks alot!

Im not the greatest when it comes to pots, but cant i simply reverse a 10k A pot to work as a 10k C?

//Mega

i don't think so

[PimpMyTone]

Thanks alot!

Im not the greatest when it comes to pots, but cant i simply reverse a 10k A pot to work as a 10k C?

//Mega

i don't think so

+ 1 

[jimilee]

Thanks alot!

Im not the greatest when it comes to pots, but cant i simply reverse a 10k A pot to work as a 10k C?

//Mega

i don't think so

yep you can,the curves are exactly the same the only difference is one goes up and one goes down.

[DutchMF]

I'm sorry Jimi, but I have to disagree with you on this. Reverse-wiring a pot doesn't change the taper, it only gives you a pot that works in reverse, ie you start with the largest resistance and when you turn the knob, it slowly decreases. The actual curve stays the same! A log type pot has a curve that rises slowly in the beginning and the gets gradually steeper, whereas a revlog one rises fast at first and then flattens out. Check out http://www.geofex.com/article_folders/potsecrets/potscret.htm, a very informative read!! (RG Keen rocks!!!!)

Paul

[jkokura]

Actually Paul, it does work. It just means the pot is backwards compared to the average pot. But yes, reverse wiring an A pot gives you C response.

Jacob

[DutchMF]

Thanks Jacob, I appreciate the reply, but I'm still not convinced.... Wish I had a scope to visualise this! But in the end, if it works, it works, right?

Paul

[jkokura]

You dont need a scope. Math is your friend here, as is the chart posted above

With the chart above, imagine the bottom left to be lug one, and the top right is lug 3, and focus on the log line. To flip them, rotate the whole chart to the left twice. Now lug 3 is down and 1 is up. But what happens is the taper has now flipped over the linear line to be antilog.

Make sense? Try it out with a real pot.

Jacob

[RobA]

It does work, you just have to pay attention to which pins go together (C: 1&2 with resistance across 2 to 3 versus A: 3&2 with resistance across 2 to 1). You can check it just using an ohmmeter too. All you need to do is look at the values at 0%, 15%, and 100% of each pot.

But, since you are using it as variable resistor in this circuit you would probably be better off doing the trick to convert a linear law pot into a reverse log law anyway. You'll get a better reverse log taper that way. R.G. Keen covers this in his Secret Life of Pots.

[Edit for clarity, that should read 50% of rotation which should give you 15% of value.]

[Megadeth]

I think i will just order one

But thanks for the concerns!


//Mega