Cry Baby Original

[Gus]

Goodrat Why are you using darlingtons?

A wha is a low voltage circuit and the darlington VBE drops will cause issues with operating points.

[Goodrat]

I didn't use darlingtons, Dunlop did. That's what is there.
OK, I put the 2x gain on the output.
Now I can increase the Q1 emitter resistor to 1.4K and that gets rid of the non symmetrical distortion at all frequencies. The wah circuit clips at lower frequencies first, otherwise I could lower the 1.4K a little more. Maybe I could tweak that.
But now I am adjusting the usual wah components to get back to a desired sweep range (need to lower the freq) due to changing the Q1 resistor.
I already had to add a  .01 across the .01 wah cap,
So I am ending up with the same output voltage, but no distortion.
More tweaking. Still not there.
See next post about the darlingtons. Possible oops.

http://www.rickviola.com/images/2xGain.JPG

[Goodrat]

Almost there. I put a trimmer on the 1.5 K (R9 feedback at Q1 base) and lowering  it to 1.2K evened out the lows . Now I can lower R15 to 1.3K. All frequencies clip at the same point.
Gain is the best I can get with no distortion with 500mVrms input to the pedal. C7 wah cap is .02 making my low end wah at 400Hz. I want that back  to 300Hz so I will play with that and hopefully not get it all out of wack.
Get rid of the darlingtons? Hmmm.
Wait, hold the phone...
I only put darlingtons in the drawing because of a trace "William" did that stated MPSA13. I thought I looked that up and verified that the "1R" marking was an MPSA13 which is a darlington.
But now my search seems to result in a 5089, or possibly an MPSA18.
Changing the drawing.

[zombiwoof]

agree, the 2 trans dunlop made vox were good , however they used the same hotpotz1 & 2 as the cb, with its fast ramp taper. what kind of taper does the bbe have?

The BBE pot has a very smooth taper, as I said it reminds me very much in sound and function as my original Vox Clyde McCoy.  Maybe not as close as an RMC Clyde copy, but very good and a lot less money.  And BBE's support is excellent, I've had a couple of issues with used BBE pedals I've bought on Ebay (not the wah), and they fixed both very quickly for no cost, no questions asked.  Joe, you should check one out sometime, and tell me what you think of it!.  And by the way, I checked which transistors were in it once, and noticed they were BC's (I think BC547, although I could be wrong).  I'm betting they are lower gain than those MPSA18's that come in most of the Dunlop Cry Baby's, as they sure get closer to the vintage sound.

I'm thinking of trying one of your new custom pots in my old Thomas Organ (TDK square inductor, Sepulveda CA) Cry Baby, as it has that abrupt taper you talk about.  Might make it more useful to me, it has a good basic sound but that fast sweep bugs me.

Thanks,
Al

[joegagan]

cool al, always appreciate your input on these threads, you have a long history with wah, i appreciate your acumen on it.

while we are on the topic, here are 10+ tips for working on wahs , some might be pretty 2nd nature, but here goes anyway.

1. stuff a rubber coated tool,  eg ;small pliers with rubber grip in between base and treadle down near the axle to hold treadle at full open when installing the pot , doing adjustments etc. helps to have the mechanism locked in the 'open' position.
1a: you can hold the pot body gently with a small pair of chanellocks for that last turn of the nut to get it really nice. just use a light touch, +depends on the pot type of course. for the body hold on older style pots, straddle the phenolic and tabs equally for even pressure.
1b. any pot with open back and a rubber cover ( condom -back) will go scratchy very quickly. i have tested nearly all brands, if there is an exception to this, i have yet to see it. please prove me wrong, i am keeping an open mind.

2. pot should be down in the saddle fairly low.

3. tensioner should put its mild pressure against the gear at the gear/pot axle centerline, not above or below. the common position in factory settings leaves the tensioner above the pot axle centerline ( with wah upside down)  and is a cause for warped rack gears. do whatever you have to to mod the tensioner to get it lower & centered.
3a : if your rack gear is warped, gently heat and straighten or replace.
3b: a small drift ( machinist term) 1-16th" or so is VERY helpful for sliding the rack gear axle pin. no need to fully remove pin to remove gear BTW

4. use as little grease as possible. even zero grease works in many setups.

5. fully  open ie; heel down is best for setting the tensioner. for testing, you can leave the screw just snug on the tensioner and swing it out of the way while you make adjustments


6 thru 10 apply to rev e and newer crybabies with the board mount jacks:

6. to remove the board, tap it lightly toward the pot opening, the wider body helps ease it out this way same applies for reinstall.
6b  : keep an 11mm socket on hand for these nuts.

7. keep your jack nuts with the board, they are sometimes not interchangeable. i have seen at least 4 different bushing depth and threads between 91 and current.

8. the hotpotz2 or hotpotz1 can benefit from a 16 tooth gear ( larger than stock). this spreads the rapid kink out a wee bit, a noticeable improvement. there is still no loss of range since the hotpotz does all of its business in 35 % or so of the pot's rotation. i sell a 'hotpotz2 smooth kit' on ebay, but i don't sell the gears, sorry. if you would like to try it, pm me here, i give a forum member special on the price.

9.  you can add a simple BJT out buffer right on the underside of the board with just a trans, two resistors and a cap, all soldered to existing pads. i will let you figure it out, but trust me it is super easy.

10. you can sneak a trubypass wire into the harness in a way that ends up looking almost original. there is an unused terminal in the stock harness. requires cutting a trace on the board right at the header and running a jumper to your input point on pcb. no need to make your trubypass look messy.  see pic



also a pic of the hotpotz2 smooth kit stuff

[candidate]

"your inductor has the wrong Q!"

this relates to mH value or saturation, or both?

[joegagan]

i wish i knew what ken exactly meant by that.
not sure what all goes into what we call Q, but i can tell you from measuring and using a lot of inductors, you can have two inductors with the same mH and overall resistance, and they can sound different. i am sure magnet type and size, wire size , type of wind/ core etc all factor in. but as far as what we exactly call Q, i am a novice.

[Goodrat]

Has anyone tried a lower value inductor and then adjust the cap?
I have hundreds of these toroids that get 1mH per turn, so I stacked 3 with 80 turns.
This one is about 160-200mH with 28 AWG mag wire so it is very low ohms.
I just tacked it in across the 500 just for grins and fiddled  the gain and feed back resistors for proper levels and put a .1 across the .01 cap and it seems to work fine. It would need more  tweaking.
I wonder why 500mH was the value chosen? I'm sure they experimented the heck out of it. But I wonder if back in the day, there was a cost reason that may not exist today.

http://www.rickviola.com/images/Inductor.jpg

[joegagan]

i have modelled in spice a lot. 500 mH is a nice middle.  
keep in mind that early voxes had  mH as low as 250, and some marshall supa wahs at similar era had up to 1.5H. changing the sweep cap is the most important in keeping the response correct for guitar when the mH goes up or down, but as mentioned before, the other components changes play into it as well. i urge anyone so inclined to download spice and play with it.

i can tell you that when i see a change in spice, then try it in real world circuit, the results are very consistent and predictable. in other words, what spice predicts, is what shows up in real sound, at least for wah in my experience. it has been a very handy tool, especially with customer wahs & trying to meet a specific sweep and response parameter.

kudos to gus, he kept  urging me to try spice and has been an awesome tutor. he has provided me with great pickup sim info along with teaching me the wah taper commands.

[Tony Forestiere]

cool al, always appreciate your input on these threads, you have a long history with wah, i appreciate your acumen on it.

while we are on the topic, here are 10+ tips for working on wahs , some might be pretty 2nd nature, but here goes anyway.

1. stuff a rubber coated tool,  eg ;small pliers with rubber grip in between base and treadle down near the axle to hold treadle at full open when installing the pot , doing adjustments etc. helps to have the mechanism locked in the 'open' position.
1a: you can hold the pot body gently with a small pair of chanellocks for that last turn of the nut to get it really nice. just use a light touch, +depends on the pot type of course. for the body hold on older style pots, straddle the phenolic and tabs equally for even pressure.
1b. any pot with open back and a rubber cover ( condom -back) will go scratchy very quickly. i have tested nearly all brands, if there is an exception to this, i have yet to see it. please prove me wrong, i am keeping an open mind.

2. pot should be down in the saddle fairly low.

3. tensioner should put its mild pressure against the gear at the gear/pot axle centerline, not above or below. the common position in factory settings leaves the tensioner above the pot axle centerline ( with wah upside down)  and is a cause for warped rack gears. do whatever you have to to mod the tensioner to get it lower & centered.
3a : if your rack gear is warped, gently heat and straighten or replace.
3b: a small drift ( machinist term) 1-16th" or so is VERY helpful for sliding the rack gear axle pin. no need to fully remove pin to remove gear BTW

4. use as little grease as possible. even zero grease works in many setups.

5. fully  open ie; heel down is best for setting the tensioner. for testing, you can leave the screw just snug on the tensioner and swing it out of the way while you make adjustments


6 thru 10 apply to rev e and newer crybabies with the board mount jacks:

6. to remove the board, tap it lightly toward the pot opening, the wider body helps ease it out this way same applies for reinstall.
6b  : keep an 11mm socket on hand for these nuts.

7. keep your jack nuts with the board, they are sometimes not interchangeable. i have seen at least 4 different bushing depth and threads between 91 and current.

8. the hotpotz2 or hotpotz1 can benefit from a 16 tooth gear ( larger than stock). this spreads the rapid kink out a wee bit, a noticeable improvement. there is still no loss of range since the hotpotz does all of its business in 35 % or so of the pot's rotation. i sell a 'hotpotz2 smooth kit' on ebay, but i don't sell the gears, sorry. if you would like to try it, pm me here, i give a forum member special on the price.

9.  you can add a simple BJT out buffer right on the underside of the board with just a trans, two resistors and a cap, all soldered to existing pads. i will let you figure it out, but trust me it is super easy.

10. you can sneak a trubypass wire into the harness in a way that ends up looking almost original. there is an unused terminal in the stock harness. requires cutting a trace on the board right at the header and running a jumper to your input point on pcb. no need to make your trubypass look messy.  see pic



also a pic of the hotpotz2 smooth kit stuff

I believe there is a candidate for  a "Sticky".

[Goodrat]

I played with Spice briefly a long time ago. It seemed unfriendly. It wasn't obvious how to get going. I should try again. I downloaded Tina. I think a lot of schools are using Tina now. I don't know if that is any good.

[joegagan]

i played with tina's sister briefly, also back in school days.

[armdnrdy]

I hope you were nice to Tina's sister.....you don't want Tina mad at you!

[joegagan]

^^^ good one! who luvs ya baby(where's my lollipop?)

[Goodrat]

Ha
Right now Tina is warning me most of my parts are not connected.
Spice and I do not get along.
It just says, "I don't like you"

[Valentinych]

I have hundreds of these toroids that get 1mH per turn...

I think there's no 1 mH, but only 1 uH. Sorry...

[zombiwoof]

cool al, always appreciate your input on these threads, you have a long history with wah, i appreciate your acumen on it.

while we are on the topic, here are 10+ tips for working on wahs , some might be pretty 2nd nature, but here goes anyway.

1. stuff a rubber coated tool,  eg ;small pliers with rubber grip in between base and treadle down near the axle to hold treadle at full open when installing the pot , doing adjustments etc. helps to have the mechanism locked in the 'open' position.
1a: you can hold the pot body gently with a small pair of chanellocks for that last turn of the nut to get it really nice. just use a light touch, +depends on the pot type of course. for the body hold on older style pots, straddle the phenolic and tabs equally for even pressure.
1b. any pot with open back and a rubber cover ( condom -back) will go scratchy very quickly. i have tested nearly all brands, if there is an exception to this, i have yet to see it. please prove me wrong, i am keeping an open mind.

2. pot should be down in the saddle fairly low.

3. tensioner should put its mild pressure against the gear at the gear/pot axle centerline, not above or below. the common position in factory settings leaves the tensioner above the pot axle centerline ( with wah upside down)  and is a cause for warped rack gears. do whatever you have to to mod the tensioner to get it lower & centered.
3a : if your rack gear is warped, gently heat and straighten or replace.
3b: a small drift ( machinist term) 1-16th" or so is VERY helpful for sliding the rack gear axle pin. no need to fully remove pin to remove gear BTW

4. use as little grease as possible. even zero grease works in many setups.

5. fully  open ie; heel down is best for setting the tensioner. for testing, you can leave the screw just snug on the tensioner and swing it out of the way while you make adjustments


6 thru 10 apply to rev e and newer crybabies with the board mount jacks:

6. to remove the board, tap it lightly toward the pot opening, the wider body helps ease it out this way same applies for reinstall.
6b  : keep an 11mm socket on hand for these nuts.

7. keep your jack nuts with the board, they are sometimes not interchangeable. i have seen at least 4 different bushing depth and threads between 91 and current.

8. the hotpotz2 or hotpotz1 can benefit from a 16 tooth gear ( larger than stock). this spreads the rapid kink out a wee bit, a noticeable improvement. there is still no loss of range since the hotpotz does all of its business in 35 % or so of the pot's rotation. i sell a 'hotpotz2 smooth kit' on ebay, but i don't sell the gears, sorry. if you would like to try it, pm me here, i give a forum member special on the price.

9.  you can add a simple BJT out buffer right on the underside of the board with just a trans, two resistors and a cap, all soldered to existing pads. i will let you figure it out, but trust me it is super easy.

10. you can sneak a trubypass wire into the harness in a way that ends up looking almost original. there is an unused terminal in the stock harness. requires cutting a trace on the board right at the header and running a jumper to your input point on pcb. no need to make your trubypass look messy.  see pic



also a pic of the hotpotz2 smooth kit stuff

Great tips, Joe!.  I would add that Geoffrey Teese posted that by changing one resistor value in a wah (sorry, I'd have to look it up to remember which one), you can more closely mimic the taper of the old "Icar" pots with a plain old HotPotzII.  Maybe you know which one I'm talking about, can't recall at the moment.  I haven't tried it myself, as I like the sealed pots or some of the Icar clones.

Thanks,
Al

[joegagan]

if i recall, teese said that changing the .2 on the wiper to .3 would get 'certain' wahs with 'certain' pots to sound more icar-ish. he then warned that results may vary. he said this a very long time ago.
i have found both in real wahs and in spice that the taper does not  change significantly until you make one 400% larger than the other, at which point other things begin to suffer.

thanks for the kudos!

while we are on the sweep/ taper topic, one overlooked mod direction is going smaller than the 1.5k from q1 B to ind. most mod sites recommend, 1.8k on up to 2.2k etc, but in some sims i have had to lower it to under 1k at times to bring everything else back into focus.. keep an open mind, do your own experiments, don't just blindly follow mods site recommendations!

[Goodrat]

Can I get a sim file for a wah that I could import?

[joegagan]

rick, i sent you some emails last night to your account listed in your profile. will send you some files, if they will work for you.