Mod GCB-95 to JH-1 Specs

[vanhansen]

Has anyone modified a stock GCB-95 Crybaby to JH-1 specs?  I've been comparing the schematics from Fuzz Central to see what the differences are.

The only differences I see are the additional .01uF cap in parallel with the inductor (opposite the 33K resistor), a .022uF cap coming off the .22uF cap and a different value pot (470K vs. 100K).

The rev of my board is Rev. E.  I do have the holes on the opposite side of the inductor to add the .01uF cap, just not sure about where exactly on mine the .022uF cap would be added.  I'll be checking that out some time this weekend.

If you want to see what the Rev. E board looks like (trace side), go to my site (link in my signature) and go to the GCB-95 page.

[al3151]

I have a Jimi Hendrix Wah Special(JH-1s) and it has 470K pot but only has a .022uF cap in parallel with the inductor.Aside from those two components the wah board is the same as the GCB-95.The board has 2 vacant spots,one is parallel to the inductor the other if I remember correctly is between the wiper of the pot and ground.

BTW I hated the way it sounded.I believe the .022uF cap is way too large.I tried .018uF,.015uF and .012uF and find .015 to be the winner IMHO.

[vanhansen]

Yours has a .022uF cap in parallel with the inductor?  According to the schematics I saw (JH-1 though), it's a .01uF.  Is that the difference between the JH-1 and JH-1s?

Does anyone have the schematic for the JH-1s?  I can't find it anywhere.  I tried google and nothing came up for "JH-1s Schematic".

[vanhansen]

Posted too soon.  I found this from the Jim Dunlop FAQ:

JH-1S Jimi Hendrix Wah Wah Special

This pedal selects the same frequency range as the JH-1, but has a different potentiometer in it. This potentiometer has a straight-lined signal change for easier control of the sweep range and for a completely different sound.

So, it looks like the schematics are the same both both JH models.

[STOMPmole]

FWIW, I owned a JH-1 for all of 2 hours before I packaged it up and returned it to the store.  In my opinion it sucks.   You can find much better wahs to build or buy and/or something more 'authentic' if you're after that Hendrix sound.

[vanhansen]

FWIW, I owned a JH-1 for all of 2 hours before I packaged it up and returned it to the store.  In my opinion it sucks.   You can find much better wahs to build or buy and/or something more 'authentic' if you're after that Hendrix sound.

I'm not looking for exactly the Hendrix sound, more like the Zakk Wylde wah sound.  He uses the JH-1 in his rig.  My GCB-95 is too trebly and I'm just trying to pull some of that out.  I'm going to start by adding the two additional caps in and see what that does.  At some point I will be changing the inductor, it's still the stock black one.  Just not sure if I should go red or yellow.

[al3151]

Yours has a .022uF cap in parallel with the inductor?  According to the schematics I saw (JH-1 though), it's a .01uF.  Is that the difference between the JH-1 and JH-1s?

I should clarrify,my JH-1s came with just one cap in parrallel to the inductor,a .022uF instead of the JH-1 standard two (one .01uF plus another .01uF cap).Thats probably just to cut cost,one component instead of two.The JH-1s was a very smooth taper wah but the frequency was way too low.In the heel down position it sounded like a low frequency oscillation,so I changed the original sweep cap(.022uF) to .015uF for starters.

[vanhansen]

I'm still confused.  The standard JH-1 looks like it only has one .01uF cap in parallel with the inductor, not two.  Unless you're talking about the .01uF that is between the 33k and 10k resistor.  I'm looking at the schematic for the JH-1 now and don't see two in parallel.  Please clarify which one this is.  The schematic I'm looking at is from Fuzz Central.

[al3151]

Sorry vanhansen, I'm kinda working from memory here(gotta stop trusting this thing).I modified the Fuzz Central schematic for the purpose of education (but I know I'm gonna get in trouble for this).This will show you how my JH-1s came stock.Notice the differences.

[vanhansen]

Ah, ha.  I see it.  The .01uF cap in parallel with the inductor isn't there but moved as a .022uF cap that looks to be in series with the inductor and the .022uF cap off the pot wiper to ground isn't there.

I wonder how much of an affect this has on the sound as apposed to the standard JH-1 with the .01uF in parallel and the .022uF off the pot wiper to ground.

Thanks for the layout.  Learning something new everyday.    I'm sure Phillip won't mind.  In fact:

"The preceding schematic was brought to you by Fuzz Central with slight changes done by al5131."  

[vanhansen]

For anyone interested, the Rev. E board doesn't have the empty location for the additional 0.022uF cap.  It does have the holes to add a cap in parallel with the inductor (next to the Output jack).  I added a 0.01uF cap there and noticed that it took out quite a bit of harshness from the circuit.  Before it had too much high end to it even after I adjusted the pot, voice mod, mid boost, etc..  Adding this cap mellowed it out some.  I updated my GCB-95 mods page with this info.  I'll be adding a pic of the modified board soon (component side).

[vanhansen]

I know this is an old thread but wanted to keep the info somewhat contained in one thread.  I have updated my GCB95 Wah page.  In addition to the usual mods, I have a JH-1 mod section added at the bottom.  I finally got the additional .022uF cap added in but settled on .015uF instead.  This info is specific to the Rev. E board but should help others with later revisions.

http://www.erikhansen.net/diy/gcb95.htm