Dunlop - JH-1 Jimi Hendrix Wah  [schematic]

All about modern commercial stompbox circuits from Electro Harmonix over MXR, Boss and Ibanez into the nineties.
Post Reply
User avatar
sevinisthenumber
Cap Cooler
Information
Posts: 453
Joined: 26 Dec 2008, 01:42
Been thanked: 29 times

Post by sevinisthenumber »

Got this all alone with no housing or anything? What is it? Any MOJO?
Attachments
100_0563.JPG
100_0560.JPG
"The man who says he knows everything will never know the truth"
C.S. Lewis

User avatar
playon
Resistor Ronker
Information
Posts: 252
Joined: 01 Jan 2008, 02:09
Been thanked: 1 time

Post by playon »

Looks like zero juju to me. It looks a little bit like the one I ripped out of a Dunlop "Jimi" wah (which sounded like ass) to replace it with the Wilson drop-in wah kit.

User avatar
theehman
Diode Debunker
Information
Posts: 710
Joined: 16 Aug 2007, 16:52
Location: Clear Creek, IN
Has thanked: 98 times
Been thanked: 105 times
Contact:

Post by theehman »

Definitely a Dunlop board> Here's the revision history from their site:

We have had many internal revisions of the GCB-95 circuit board but the general differences are as follows:
Rev. C and earlier did not have an AC adaptor jack ('89 and earlier);
Rev. D incorporated an AC adaptor jack ('89 - '90);
Rev. E was the first to have pc-mounted jacks ('90 - '91);
Rev. F incorporated buffered circuitry for improved performance ('91 - '92);
Rev. G switched to a coaxial (barrel-style) AC adaptor jack ('92 - present).

You can determine the revision number of your Crybaby pedal by looking at the bottom of the PC-board (you will have to remove it from the housing) and look at the ECB-25 (letter), this represents the revision number of the pc-board. If there is not an ECB-25#, then you have a Crybaby manufactured earlier than 1990.
Ron Neely II
Electro-Harmonix info: http://electroharmonix.vintageusaguitars.com
Home of RonSound effects: http://www.ronsound.com
fx schematics and repairs

User avatar
dubelectro
Information
Posts: 1
Joined: 07 Nov 2007, 06:27
Has thanked: 2 times

Post by dubelectro »

Hi,

It is certainly "Jimi Hendrix" wah Model JH-1.
I have a same board.
I got it in early 90's.
Attachments
DVC00223.JPG
DVC00223.JPG (31.49 KiB) Viewed 4806 times

User avatar
puppiesonacid
Cap Cooler
Information
Posts: 672
Joined: 02 Apr 2008, 14:41
Has thanked: 9 times
Been thanked: 12 times

Post by puppiesonacid »

its definetly an early 80's dunlop wah board, although there seems to be other opinions. from what research I've done, b/c of the dc jack its 80's, maybe not early.

User avatar
playon
Resistor Ronker
Information
Posts: 252
Joined: 01 Jan 2008, 02:09
Been thanked: 1 time

Post by playon »

I highly recommend these:

http://www.wilsoneffects.com/Wahkits.html

After owning numerous wahs including vintage Jen, Thomas, DeArmond, etc this wah is the best and most versatile I've had, it kicked the Teese RMC III off my board.

User avatar
puppiesonacid
Cap Cooler
Information
Posts: 672
Joined: 02 Apr 2008, 14:41
Has thanked: 9 times
Been thanked: 12 times

Post by puppiesonacid »

playon wrote:I highly recommend these:

http://www.wilsoneffects.com/Wahkits.html

After owning numerous wahs including vintage Jen, Thomas, DeArmond, etc this wah is the best and most versatile I've had, it kicked the Teese RMC III off my board.
looks like the stuff from fuzzcentral.com

BTW seven, no MOJO. Just a wah, its all in the foot and tuning the pot.

User avatar
lolbou
Old Solderhand
Information
Posts: 2617
Joined: 18 Nov 2008, 21:38
Has thanked: 308 times
Been thanked: 225 times

Post by lolbou »

Hi everyone,

Finally dig this one out.

I bought it some two years ago for dirt cheap. It did took me a long time to look at it closely and to exactly compare its guts with all other wahs.

I guess it's dated from 1990 the pot it had (Hot Potz-1 - date code 9033). And it would somehow match the presence of the 3.5" DC jack plug.

Seems like they were recycling the fully populated Cry-Baby Rev C. boards to make these early JH-1... :hmmm:
Early JH-1 schematic.gif
Here are the two extra caps that were in it:
capas.jpg
The glass package one (looks like a SMD cap inside it) clearly shows the 103 code (10nF) and "MEXICO" :wink: . The other looks like a resistor but again, the code shows orange-orange-brown for 330p. Both measures what expected (sorry for the bad color, I used my scanner).

The 22n sweep cap can be shown on the pic below:
board.jpg
From what I've read (including here), 22n is quite common as a sweep cap in a JH-1 wah. This cap has been added after the removal of another one (the Crybaby's 10nF for sure) as solder has been clearly remelted. Still I can't be sure that this has been done in the factory considering I bought the unit second hand (but looking stock). You can also see the flux traces around the 33k resistor lugs.

It's not the over-hyped unit I know, but the only schematics available on the internet for this wah are the latest versions. I guess it worth the record.

Might be a sorta collectible one if it's that rare? Forget it, I tear it down to pieces... :slap: :slap: :slap:

Nevermind, I would have kept it anyway if valuable... :wink:

ps: there are posts on this forum where I mention the glass cap as being a diode :roll: :lol: ... I'd like to thank you all for the education I got here since then... :hug:
- Are you a mod or a rocker?
- Uh, no, I'm a mocker.

User avatar
sinner
Old Solderhand
Information
Posts: 4709
Joined: 06 Nov 2008, 17:16
Location: ...no more
Has thanked: 1031 times
Been thanked: 909 times

Post by sinner »

Cap across inductor? What effect does it make?

Thanks for schemo :thumbsup

User avatar
lolbou
Old Solderhand
Information
Posts: 2617
Joined: 18 Nov 2008, 21:38
Has thanked: 308 times
Been thanked: 225 times

Post by lolbou »

sinner wrote:Cap across inductor? What effect does it make?
From what can be found about later JH-1 wah models, the mods I found in this unit were kept for future production, with values sometimes altered. The input buffer has been added later on too...

I don't really know what it can do, but I guess it creates a R,L,C parallel filter (and not only R,L), coupled with the sweep cap to produce the bandpass filtering. This might change Q or resonance frequency? Boy, my filter theory is way too deep in my brain's attic...

I'll amend my PSpice model to check for changes and provide some results if these simulations can be considered valuable...
- Are you a mod or a rocker?
- Uh, no, I'm a mocker.

User avatar
lolbou
Old Solderhand
Information
Posts: 2617
Joined: 18 Nov 2008, 21:38
Has thanked: 308 times
Been thanked: 225 times

Post by lolbou »

Ok, here's what I end up with the simulation. The two units compared are a standard Rev C wah (original values) and the early JH-1 (with the mods specified in the schem). I did not place the power supply section but left a single battery instead. The AC magnitude for the signal source is set up to 100mV.

Toes up (lower end):
Standard Rev. C - toes up.
Standard Rev. C - toes up.
Early JH-1 - toes up.
Early JH-1 - toes up.
Toes down (higher end):
Standard Rev. C - toes down.
Standard Rev. C - toes down.
Early JH-1 - toes down.
Early JH-1 - toes down.
So, it appears that the sweep range drifts to lower frequencies. The variation seems more dramatic in the higher end (from A5 to C5) than in the lower end (from A3 to D#3). And the peak is narrower in the high frequencies for the JH-1.

It seems to match Dunlop's explanation here, though I can't get the "more open sound" thing to match a tighter and lower bandpass :scratch: :
Dunlop website wrote:JH1D Jimi Hendrix Wah Wah (Formerly JH-1 and JH-1B)
The JH-1 is an altered GCB95. Legend has it that before Jimi used his Crybaby pedal, he would have his tech alter it so that the frequency range selected would be at a slightly lower-pitch. This pedal has a fatter, more open sound than the GCB95.
- Are you a mod or a rocker?
- Uh, no, I'm a mocker.

User avatar
Effectsiation
Information
Posts: 42
Joined: 09 May 2008, 18:18
Has thanked: 7 times

Post by Effectsiation »

Hi folks, I was wondering if anyone knew what the difference is between the:

Dunlop JH-1
Dunlop JH-1S (marked as Jimi Hendrix "Special")


I don't mean the new ones (marked JH-1B, and JH-1D respectively), the JH-1S is just as old as the original JH-1 I think.

Anyway, if someone could school me on differences that would be swell, thanks!

User avatar
Effectsiation
Information
Posts: 42
Joined: 09 May 2008, 18:18
Has thanked: 7 times

Post by Effectsiation »

Nevermind, found my answer here: https://www.diystompboxes.com/smfforum/ ... ic=27050.0
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.
Thanks!

User avatar
Victor Nery
Information
Posts: 49
Joined: 18 Nov 2011, 03:29
Has thanked: 31 times
Been thanked: 6 times

Post by Victor Nery »

Greetings,

How does the 330pF capacitor modify the response (the taper?) of the potentiometer? Is there a math to calculate its influence and to determine the changes in frequency according to the pot rotation?

Thanks in advance

Post Reply