Hot Potz II Taper and Wah Tapers in General

[YouAre]

Hey Guys,

This thread is pointless...well this post is at least because I'm sitting here promising to do a few things.

Firstly: Plot the taper/resistance curve of the Dunlop Hot Potz II in a fashion that is similar to this

Sorry for the giant filesize. And if reposting that picture aint Kosher, let me know please!

I have looked for something like that, but I haven't seen it before. So I plan on doing this in a really simple and probably inefficient way. I'm going to turn the potentiometer in excruciatingly fine intervals, and measuring the resistance between both sets of lugs, and graphing it in Excel. Is there any demand for this? If you guys want to know what's going on inside that magical little pot, but don't have the time to do it yourselves...I'll do it for you....in 2 weeks (finals at college....)


Also, at what resistance range/taper do you guys like for a nice easily controllable wah? From the "wakka wakka" to the weeping wails, where does the magic happen? I'd like to investigate this myself, but that will be a bit more difficult. I'm still going to check it out personally (somehow...), but what do you guys like?

[ayayay!]

Honestly, I used to say Hot Potz II's were fine, but anymore I keep running into ones that have a really bad "gnarly" spot that kinda hangs about 2/3 of the way through.  Maybe it was a bad batch?

I've now been more happy with the ICAR tapers like SmallBear's 100k offering. 

I'll be watching your results. 

[YouAre]

Ideally, I want to find the region where that abruptness occurs, and to see how we can use and adapt a standard cheap pot to get the job done. Once we figure that out, I want to find what range of the wah pot is useful. Cause I know on many wah pedals, most of the taper is bass heavy, then gets to treble really quickly. So to have a "full range" treadle/expression pedal would be pretty useless, because you're only going to need the upper half of the rotation anyway. So basically my goal is to utilize a standard crybaby/vox shell, or any other readily available wah shell, and have it go from lowest useful bass frequency at the heel to maximum treble at the toe. Now since I figure some people like to have a little bit of the expression pedal travel be some of that "redundant" bass before it starts transitioning to treble, so I'll try to portion that in as well.

So here's the game plan:
-Map resistance of Hot Potz II
-Shameless beg you guys to donate your wah pots to be measured and tested in circuits  (I really want to try a hot potz i, hehe).
-Replace wah pot with linear 100k pot and measure the resistances where all the smooth transitions go down.
-See what degree of rotation that is on the potentiometer
-Measure the degree of rotation on a standard crybaby (it'll be a range, cause people mess with the bumpers on the pedal)
-Test out the wah with a 100kA and 100kC style knobs in the same manner I did with the 100kB
-Map out THOSE degrees of rotation

Hopefully the end result will be a totally "efficient" wah pot. No useless excess of bass travel, and not having to use the whole pot to get the job done. The reason that I would like to avoid using the whole pot because I know everyone here adjusts the rack and gear on their crybabies to get the maximum amount of treble (maybe not everyone). So when you push forward to hit the bypass switch, you might be pushing the pot past it's limit or forcing it to rotate further. That has got to reduce the life of that pot, and is a potential for failure that I can't accept.

Please someone look into the question below. That is where I am going to need your guys' help!!!

Part of all this has to do with my understanding of the design of wah pedals themselves as well. Like, what is the higher limit of frequency a wah pot can achieve in a wah circuit. I understand resistance has little to do with that frequency because the pot is just a voltage divider, and it's more about getting to that maximum rotation of the pot (whatever the value) to achieve that frequency. But is there a way to reach that frequency on the potentiometer WITHOUT getting to that maximum part of rotation on the potentiometer? Cause that would be just awesome. 





Well, all this is moot until....I FINISH MY OTHER WORK! I hate that I get this motivation to do work for the effects communities right when I have deadlines of my own. Seriously guys, keep this discussion going on for another week at least so that I stay motivated to really designing something useful. Once I tackle this project, It's on to switchless wah's!


Thanks guys, let's keep this thread alive!

[zombiwoof]

Ideally, I want to find the region where that abruptness occurs, and to see how we can use and adapt a standard cheap pot to get the job done. Once we figure that out, I want to find what range of the wah pot is useful. Cause I know on many wah pedals, most of the taper is bass heavy, then gets to treble really quickly. So to have a "full range" treadle/expression pedal would be pretty useless, because you're only going to need the upper half of the rotation anyway. So basically my goal is to utilize a standard crybaby/vox shell, or any other readily available wah shell, and have it go from lowest useful bass frequency at the heel to maximum treble at the toe. Now since I figure some people like to have a little bit of the expression pedal travel be some of that "redundant" bass before it starts transitioning to treble, so I'll try to portion that in as well.

So here's the game plan:
-Map resistance of Hot Potz II
-Shameless beg you guys to donate your wah pots to be measured and tested in circuits  (I really want to try a hot potz i, hehe).
-Replace wah pot with linear 100k pot and measure the resistances where all the smooth transitions go down.
-See what degree of rotation that is on the potentiometer
-Measure the degree of rotation on a standard crybaby (it'll be a range, cause people mess with the bumpers on the pedal)
-Test out the wah with a 100kA and 100kC style knobs in the same manner I did with the 100kB
-Map out THOSE degrees of rotation

Hopefully the end result will be a totally "efficient" wah pot. No useless excess of bass travel, and not having to use the whole pot to get the job done. The reason that I would like to avoid using the whole pot because I know everyone here adjusts the rack and gear on their crybabies to get the maximum amount of treble (maybe not everyone). So when you push forward to hit the bypass switch, you might be pushing the pot past it's limit or forcing it to rotate further. That has got to reduce the life of that pot, and is a potential for failure that I can't accept.

Please someone look into the question below. That is where I am going to need your guys' help!!!

Part of all this has to do with my understanding of the design of wah pedals themselves as well. Like, what is the higher limit of frequency a wah pot can achieve in a wah circuit. I understand resistance has little to do with that frequency because the pot is just a voltage divider, and it's more about getting to that maximum rotation of the pot (whatever the value) to achieve that frequency. But is there a way to reach that frequency on the potentiometer WITHOUT getting to that maximum part of rotation on the potentiometer? Cause that would be just awesome. 





Well, all this is moot until....I FINISH MY OTHER WORK! I hate that I get this motivation to do work for the effects communities right when I have deadlines of my own. Seriously guys, keep this discussion going on for another week at least so that I stay motivated to really designing something useful. Once I tackle this project, It's on to switchless wah's!


Thanks guys, let's keep this thread alive!

I'm wondering why you want to copy the taper of the HotPotz II, why not copy the ICAR taper that the original wahs used?.  This is the taper that the clone pots are emulating (the Blacktop pot, the Fulltone, etc.).  I think the HP II is basically a linear pot, from what some have reported after plotting the taper.  IMO the ICAR taper is much better than whatever the HotPotz II has.  I've never had any problem with any wah pot running out of room when adjusting the gear, there is extra travel built in to them.

Maybe I'm missing something here.

Al

[YouAre]

I'm wondering why you want to copy the taper of the HotPotz II, why not copy the ICAR taper that the original wahs used?.  This is the taper that the clone pots are emulating (the Blacktop pot, the Fulltone, etc.).  I think the HP II is basically a linear pot, from what some have reported after plotting the taper.  IMO the ICAR taper is much better than whatever the HotPotz II has.  I've never had any problem with any wah pot running out of room when adjusting the gear, there is extra travel built in to them.

Maybe I'm missing something here.

Al

Simply cause.....I have the Hot Potz II 

Also in my experiences, I like the Hot Potz II better for my playing/music style than the ICAR (Mainly a hard rock guy myself. I like Slash's wah style moreso than someone who uses a vox). ALSO, there's a mod by Geoffrey Teese that can make a Hot Potz II mimic the ICAR taper. There is no reverse, so it's in my interest to study the Hot Potz, since we can retrofit an "ICAR Taper Mod."

[Joe Hart]

I would be very interested in learning about the different tapers and how to "adjust" them. The biggest issue I've had with wahs is the abrupt (and unpleasant -- at least to me) change in tone a lot of them have.
-Joe Hart

[Paul Marossy]

According to Geoferry Teese, changing the 0.22uF caps to 0.33uF caps approximates the ICAR taper. I haven't tried this for myself, but I think I am going to try it just for kicks.

[zombiwoof]

I'm wondering why you want to copy the taper of the HotPotz II, why not copy the ICAR taper that the original wahs used?.  This is the taper that the clone pots are emulating (the Blacktop pot, the Fulltone, etc.).  I think the HP II is basically a linear pot, from what some have reported after plotting the taper.  IMO the ICAR taper is much better than whatever the HotPotz II has.  I've never had any problem with any wah pot running out of room when adjusting the gear, there is extra travel built in to them.

Maybe I'm missing something here.

Al

Simply cause.....I have the Hot Potz II 

Also in my experiences, I like the Hot Potz II better for my playing/music style than the ICAR (Mainly a hard rock guy myself. I like Slash's wah style moreso than someone who uses a vox). ALSO, there's a mod by Geoffrey Teese that can make a Hot Potz II mimic the ICAR taper. There is no reverse, so it's in my interest to study the Hot Potz, since we can retrofit an "ICAR Taper Mod."

Gotcha.  Please report what you find out about the taper on the HP II, as someone else once said it was just linear.  I also wonder what the taper was on the HotPotz I, which you can still find around.  I liked the HP I better than the II, I have heard that the HP I might have been an "S" taper, but I've not heard that it was verified.

Al

[YouAre]

I would be very interested in learning about the different tapers and how to "adjust" them. The biggest issue I've had with wahs is the abrupt (and unpleasant -- at least to me) change in tone a lot of them have.
-Joe Hart

Joe,

Awesome! Do me a favor. Please please please keep reminding me to do this in a weeks time. School will let up by then, and hopefully by that time, I'll be able to do all this work in the lab, and have things be a lot easier. Seriously, I have an issue where I come up with great ambitious ideas to do during finals period. But usually once finals are done, my brain is so fried, I forget what I wanted to do to begin with. It'd be doing me a huge favor 

According to Geoferry Teese, changing the 0.22uF caps to 0.33uF caps approximates the ICAR taper. I haven't tried this for myself, but I think I am going to try it just for kicks.

Bingo! Sorry if I made it sound like I had some secret mojo info. Didn't mean for it to come off that way. But actually, I think Teese said to change the .22uf Cap that feeds the wiper. I don't think he said both. Am I right?

Gotcha.  Please report what you find out about the taper on the HP II, as someone else once said it was just linear.  I also wonder what the taper was on the HotPotz I, which you can still find around.  I liked the HP I better than the II, I have heard that the HP I might have been an "S" taper, but I've not heard that it was verified.

Al

Will do! Like I said before, in two weeks you can respond in this thread, PM me, email me (yield96 at hotmail), throw rocks at my window, or do whatever you can to make sure I do this. This forum has given me a LOT over the years, this is the least I can do.

Regards,
Murad

[imbuedblue]

But actually, I think Teese said to change the .22uf Cap that feeds the wiper. I don't think he said both. Am I right?

You are correct, sir.

[YouAre]

You are correct, sir.

Thank you! So yeah, swapping the .22uF cap that leads to the middle lug of the pot could lead to a "ICAR Switch. How cool would that be?!?!

[Paul Marossy]

You are correct, sir.

Thank you! So yeah, swapping the .22uF cap that leads to the middle lug of the pot could lead to a "ICAR Switch. How cool would that be?!?!

Oh, it's just the cap on the wiper? I could have sworn it was both caps, but I guess my memory failed me this time. I guess it makes more sense for it to be the cap on the wiper when I think about it a little bit.

[imbuedblue]

With all the fuss about taper in wahs, has anyone ever tried throwing an exponential converter into a wah?

[Joe Hart]

Joe,

Awesome! Do me a favor. Please please please keep reminding me to do this in a weeks time. School will let up by then, and hopefully by that time, I'll be able to do all this work in the lab, and have things be a lot easier. Seriously, I have an issue where I come up with great ambitious ideas to do during finals period. But usually once finals are done, my brain is so fried, I forget what I wanted to do to begin with. It'd be doing me a huge favor 

Okay, I will!
-Joe Hart

[Joe Hart]

I think you're out of school now?  Did you start this?  Just a reminder!!
-Joe Hart

[YouAre]

I think you're out of school now?  Did you start this?  Just a reminder!!
-Joe Hart

Working on it

Having some issues mounting the pot to a scale so I can take the measurements in even increments. Truth be told, it doesn't matter if the increments are exact, because as long as I take X amount of points between 0 and 300 degrees, I should be fine. Working on that, and I'll have it done by the end of the week!

[YouAre]

Welly ladies and germs,

I did what I promised I would do, and I even measured the taper of a Vox stock v847 pot. I'm heading out to work now, but I figured I would let you guys know. Also, if any of you can host the Excel file/picture of the chart so I don't have to email it to everyone, that would be greatly appreciated. Thanks!

[richon]

you could upload it to some free pages that will let you share it with all of us.


PS: did you test increasing the cap to 0.33uF?

[YouAre]

I did not check it with the .33uF cap because I literally just mapped the resistance as I rotated the pot in mostly even increments. It might give an idea of what the wah taper should look like.

Anyone know of a website I can upload this to? It'd be easy if I could email it to someone because it's literally an Excel image.

Finally, after reading the technology of wah pots, I still don't understand how the wah pot is acting as a voltage divider. Doesn't that mean the output should be in the middle lug? Can someone explain the voltage divider aspect and how it relates to the output of the wah? Are we just messing with the voltage that's feeding to Q2's emitter from Q1's collector? Any insight?

[zombiwoof]

I'm not an expert at this stuff, but couldn't you scan the image and upload it to a photo hosting site, like Photobucket, like you do with pictures?.

Al