Pot Taper mystery??

[Govmnt_Lacky]

I found a pot laying around and I cannot find any taper marking on it 

After applying the DMM, I found that it is a 100K pot. Now, I measured resistance between Lugs 1 & 2 while rotating the pot and this is what I get:

0% rotation = 42 ohms
25% rotation = 6.4K ohms
50% rotation = 102K ohms
75% rotation = 102.5K ohms
100% rotation = 103K ohms

Can someone help me out with a taper 

Thanks 

[Thump-Lump]

Antilog?

A rather basic site that explains pots....  http://sound.westhost.com/pots.htm

[Seven64]

turn it to 50%.  if it is the same value at 1 & 2 that it is at 2 & 3 its linear, if not its log

[Govmnt_Lacky]

turn it to 50%.  if it is the same value at 1 & 2 that it is at 2 & 3 its linear, if not its log

When turned to 50%, it is as follows:

CCW to middle = 102K

CW to middle = 2K

CCW to CW = 103K

So I guess it is Log BUT..... is it an A-type log taper OR is it a C-type log taper?

[Seven64]

doesnt matter because you can just switch how you wire 1 & 3

[Govmnt_Lacky]

I am asking because I think this pot is a good candidate for a wah pot. I just want to make sure that it has an acceptable taper. I am not too savvy on wah technology and the articles I have read (Geofx, etc.) do not elude to the pot taper other than to say that ICAR is good or else it gives brands to try (i.e. HotPotz, CTS, etc.)

Does anyone know what the taper curve or pot measurements are for a GOOD wah pot?

[Thump-Lump]

Taper       Old Code     New Code     Alternate

Linear              A                 B              LIN
Log (Audio)     C                 A              LOG
Antilog             F               N/A             N/A

[Seven64]

on pots:

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

and the all inclusive wah article:

http://geofex.com/Article_Folders/wahpedl/wahped.htm

it says something about how most wah pots seem to have a specialty taper

[Govmnt_Lacky]

on pots:

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

and the all inclusive wah article:

http://geofex.com/Article_Folders/wahpedl/wahped.htm

it says something about how most wah pots seem to have a specialty taper

I have read these already. What they do not alude to is the answer to my original questions.

1) What taper is the pot I have in hand? -AND-

2) What is the typical/ideal taper for wah pots?

I think it is Anti-log/Rev Log however, is this indicative of a C-type taper?

[joegagan]

when measured in the actual pedal, icar is a slower  ramp, nearly linear ( in actual use) response. when measured as a pot, it looks similar to log, but not exactly log as defined by most mfgrs.

hotpotz 1 and 2, and thomas CB /vox pots all have more of a 'kink' , even when measured in the pedal as it travels. by kink, i mean there is a part of the ramp that is steep.

the original 25k pots in boomerangs have what looks like a linear movement when measured in the pedal. even more linear than icar. the entire spectrum is full represented, giving the player the ability to explore the finer details at any given point along the sonic rainbow. in comparison, a crybaby with stock pot is like a clutch in a racing ferrari. in. out. i think that is why a lot of people like icar when they try it, better control across the spectrum.

the upside of the quick ramp on the CB is a talky quality with very little foot movement. feels like  'quick response' to some players. horses for courses.

[joegagan]

gov't lacky, after looking at your numbers, i would guess that is a CB 70s or hotpotz 1

[Govmnt_Lacky]

when measured in the actual pedal, icar is a slower  ramp, nearly linear ( in actual use) response. when measured as a pot, it looks similar to log, but not exactly log as defined by most mfgrs.

Thanks Joe,

I am kind of perplexed 

You mention that the pot I have would be close to a HotPotZ 1 or a 70's CB however, the sweep appears to be Anti-Log. Didn't you mention above that the "good" tapers had a Logrithmic quality?

So did they wire these 70's CB and HotPotz 1's backwards to get the Log function out of an Anti-log pot?

[Paul Marossy]

a crybaby with stock pot is like a clutch in a racing ferrari. in. out. i think that is why a lot of people like icar when they try it, better control across the spectrum.

the upside of the quick ramp on the CB is a talky quality with very little foot movement. feels like  'quick response' to some players. horses for courses.

That must by one reason I don't like the CryBaby. It's like on/off and I don't like that. And the Boomerang shell design seems to give you much better control.

[joegagan]

i never went back and analyzed what the tapers were with scrutiny. but, the CB pot orientation is simply the way the common organ thomas and vox pedals were in the 60s. there was no attempt to accommodate a specific taper as far as i know. i have a 67 vox volume pedal with a 500k or 470k icar in it, i should check the taper of that one.

[joegagan]

the classic thomas/hotpotz formula looks to me, like a more radical reverse log. the kink is more radical than any of the log graphs i've seen. those hotpotz will amaze you, you can sometimes see 90% of the value change occur over 15 to 20% of the rotation. kinky!

[zombiwoof]

I read somewhere that the original "Icar" pot had an "S" taper, but I don't know if that is true or not.  Maybe someone more knowledgeable than me can explain that (I assume when plotted on a graph, it has an "S" shape).  That's supposedly why the later pots that had more of a linear taper didn't have the same feel to them.

Al

[Govmnt_Lacky]

I read somewhere that the original "Icar" pot had an "S" taper, but I don't know if that is true or not. 

I read that somewhere as well. I do not understand it though. Let me TRY TO explain:

If the illustrious ICAR taper pots were in fact S-taper... meaning that their taper curve looked like an S on the graph, then how would it work on the treadle? I ask because allegedly the Hot Potz 1 & 2 and some of the other pots I have heard mentioned were graphed REVERSE of this notion.

With the S-taper, as you turned the pot from CCW to CW, the resistance would rise SLOWLY at the first 20-25% of the rotation, then it would rise quickly through 25-75%, then level off on the last 25% of rotation.

With the Hot Potz series, on the first 20% of rotation from CCW to CW, there is a LARGE increase in resistance. You would have about 90% of the total resistance by the time you got to 50% of the pot's rotation.

It just does not make sense to me. Does anyone else have an light to shed on the subject??

[Paul Marossy]

I read somewhere that the original "Icar" pot had an "S" taper, but I don't know if that is true or not.  Maybe someone more knowledgeable than me can explain that (I assume when plotted on a graph, it has an "S" shape).  That's supposedly why the later pots that had more of a linear taper didn't have the same feel to them.

Al

I thought that I read that at GEO. Or maybe RG said it in some threads here. But IIRC it was something authored by RG.

[joegagan]

quote govtlacky
With the S-taper, as you turned the pot from CCW to CW, the resistance would rise SLOWLY at the first 20-25% of the rotation, then it would rise quickly through 25-75%, then level off on the last 25% of rotation.

With the Hot Potz series, on the first 20% of rotation from CCW to CW, there is a LARGE increase in resistance. You would have about 90% of the total resistance by the time you got to 50% of the pot's rotation.

i don't know enough about S taper to comment, however when measured, the rise of every icar repro ( 4 distinct brands tested) is more gradual over the entire rotation than hotpotzers. when installed in a crybaby or vox, it translates to a roughly approximate linear line on the graph. btw, all icar repros tested were within about 5% of each other. they all did their homework, (or borrowed?)

your descrip of the hotpotz taper is exactly right. you are describing the kink i refer to. when measure from clockwise backward, it does near nothing til  somewhere near 50% , then BAM>

[n8b]

I can't help with the taper, but I have a pair of pots out of a Thomas Organ Stereo Fuzz Wah that measure similarly, if not the same. One of them was scratchy, so I pulled them out and tried to resurrect the scratchy pot. The pedal didn't seem to work right with the pots installed, so I replaced them with a 100k dual linear pot and now the wah sounds great and pans.

I found a pot laying around and I cannot find any taper marking on it 

After applying the DMM, I found that it is a 100K pot. Now, I measured resistance between Lugs 1 & 2 while rotating the pot and this is what I get:

0% rotation = 42 ohms
25% rotation = 6.4K ohms
50% rotation = 102K ohms
75% rotation = 102.5K ohms
100% rotation = 103K ohms

Can someone help me out with a taper 

Thanks