A few Tearjerker Mod questions

[JHKcustoms]

I’m working on some finishing touches on my tearjerker wah build and had a few questions about some mods I’d like to implement..

I’m curious about the Q and Mid pots: they are listed as 100k for Q and 2k for Mid, I’d like to have these on the side but I’m not sure what kind of pots to get for each? As in audio linear etc… as it’s not listed on the data sheet.
Thanks ahead of time
-JHK

 

[JHKcustoms]

Honestly I’d love to know which type for each of the trim pots if anyone knows.

 

[mkstewartesq]

Hi – when I built my Tearjerker, I put all the trim pots on the outside as well. The advice I received at the time was that trim pots are generally linear, and so a linear pot would be the usual replacement – but that you could always experiment with a different taper. I just went with linear for all of mine.

Mike

 

[JHKcustoms]

Right on !
Thanks man and what a beautiful looking build ! By the way, Did you manufacture your face plate or use a service ?

 

[mkstewartesq]

Right on !
Thanks man and what a beautiful looking build ! By the way, Did you manufacture your face plate or use a service ?

Thanks! That face plate actually came with the enclosure. The enclosure was originally a Mission expression pedal, which I gutted to use for my wah build.

 

[JHKcustoms]

Oh gotcha, thank you, I’m working with an old slash sig wah enclosure and I’ve pulled off the face plate, so I’m looking for a spot to make a replacement, but maybe I’ll just cut a new plate and decal it.

 

[Big Monk]

I’m working on some finishing touches on my tearjerker wah build and had a few questions about some mods I’d like to implement..

I’m curious about the Q and Mid pots: they are listed as 100k for Q and 2k for Mid, I’d like to have these on the side but I’m not sure what kind of pots to get for each? As in audio linear etc… as it’s not listed on the data sheet.
Thanks ahead of time
-JHK

Not a Wah expert but if I can make a few suggestions based on experience:

1.) I've found that the Q pot works better as a set and forget.

2.) The "Mids" pot works more like a Q pot than the Q pot does, in my personal experience.

3.) I believe when I had both external, I also used Linear taper.

 

[JHKcustoms]

Thank you so much for your insight!! I’m personally a bit mercurial on the Q so I tend to mess with it depending on the tune/gig and make dots with a setting saver pen. As for the mids I agree, but I think I’ll do volume as well since they’re all linear, I wish there was a gain knob though I’m sure it’s not too tricky to add one to the circuit.

 

[mkstewartesq]

Thank you so much for your insight!! I’m personally a bit mercurial on the Q so I tend to mess with it depending on the tune/gig and make dots with a setting saver pen. As for the mids I agree, but I think I’ll do volume as well since they’re all linear, I wish there was a gain knob though I’m sure it’s not too tricky to add one to the circuit.

I'm not so sure it doesn't have a gain control (this is frankly why I find this build so confusing to calibrate - the "names" of the trimpots don't seem to necessarily follow their function). So I snipped the following from a post Robert made a while back and keep it on my phone so I have a ready reference should I need it. (Sorry for not linking to the original post - I can't readily find it, and had the excerpt handy on my phone).

"VOL controls the input impedance of the input stage

LOW adjust the gain of the input stage

MID controls the amount of negative feedback

Q adjusts the resonance of the inductor

The dip switches adjust the center frequency of sweep, they're like a more flexible version of the rotary switch on a 535Q wah.

These were all derived from popular modifications that are done to the original Crybaby circuit.

Here's a little bit of info about each one (except the VOL control) from the ElectroSmash Crybaby analysis.

LOW
8.4. More Bass and Gain Modification. The emitter resistor R4 controls the gain level of the effected signal. Reducing it will result in a slight addition of gain and bass content.

MID
8.5 More Mid Content Modification. This mod subtle sets the midrange content. Increasing the value of the R2 resistor the heel-down position will sound slightly more strong and emphasized. Typical values for this mod are 2KΩ and 2.7KΩ (default R2 resistor is 1.5KΩ).

Q
8.2 Modifying the Wah-Wah Q factor or "Vocal Mod". The Quality Factor is a parameter that characterizes how narrow or spread is the selected frequency band. The 33KΩ resistor R7 adjusts this sharpness of the resonant peak. This modification is also known as “Vocal Mod”, some users replace the 33K for a bigger one like 39KΩ, 68KΩ or even 100KΩ to have more vocal sounding.

DIPSWITCHES
8.3. Modifying the Sweep Range or "Bass Players Mod".
The C2 cap determines the center frequency of the wah sweep. Changing C2 the whole wah sweep range moves up or down. In the images below the shift of the sweep range can be appreciated, using 0.1uF, 0.01uF (default) and 0.001uF."

 

[JHKcustoms]

Oh wow that’s fantastic!
I understand what you mean about the control names, that is confusing.
Thank you so much for sharing that!