Author Topic: Help!! Morley classic Wah  (Read 4431 times)

ace7789

Help!! Morley classic Wah
« on: February 11, 2015, 03:45:10 AM »
I have a Morley Classic Wah (Black CLW). Was given to me as a present for my birthday about 5 years ago. While I like the wah sound it puts out, I'm finding that I really don't have a reason to use the wah effect almost ever.

I would, however, love to have a volume pedal. Doing the research it looks like the only instructionals around are for Crybabys and other more popular wah pedals. I know a few things about electronics, and I've done some basic soldering and things before, and eventually I'd like to be able to make my own pedals, so I figured this would be as good a place as any to start. Is there anyone who's done a mod like this before with the Classic Wah? Or are wah pedals built similarly enough to where the crybaby mods, or even the morley power wah instructionals would still guide me through this mod?

Any help would be hot, thank you!

GGBB

Re: Help!! Morley classic Wah
« Reply #1 on: February 11, 2015, 08:58:31 AM »
Morley makes their schematics publicly available: http://www.morleypedals.com/downloads.html. They also often share PCBs between different models, so it could be that your wah has the same PCB as one of their volume pedals. Open it up and look for a model number on the PCB (usually top-right corner). If there are more than one listed, yours will be checked off (CLW). See if any of the other models are a volume pedal. If one is, you could just replace the necessary components according to the schematic. Otherwise, Morleys are not as simple as conventional volume pedals which are little more than a pot - they are LED/LDR based, so it might be a bit more challenging but still doable. Compare the schematics for your unit and one of their volume pedals to see if it looks like something you could manage by changing components, adding jumpers etc. to fit the volume circuit on the wah PCB.
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Transmogrifox

Re: Help!! Morley classic Wah
« Reply #2 on: February 11, 2015, 10:58:47 AM »
Just looked at the schematic.  This one is easy:
Remove the following from the board:
C1
C5
C6

Put a jumper between LDR3  (use the pad from which you removed C5 or C6) and R1 (use pad from which C1 was removed.

Experiment with different values for R1 to get the kind of sweep you want.  Play with values of R6 to set the final output level.  *EDIT* You mentioned your are new to this, so I thought I would add larger values of R6 will make it louder.  Smaller values of R1 will result in making it louder too, but it will reduce the "depth".  You will probably want to make R1 bigger and then if that makes the final output too quiet, then make R6 bigger.

The first thing I suggest to do with R1 and R6 is change R1 to a 330k and see how it sounds.
« Last Edit: February 11, 2015, 11:01:45 AM by Transmogrifox »
trans·mog·ri·fy
tr.v. trans·mog·ri·fied, trans·mog·ri·fy·ing, trans·mog·ri·fies To change into a different shape or form, especially one that is fantastic or bizarre.

ace7789

Re: Help!! Morley classic Wah
« Reply #3 on: February 12, 2015, 07:04:35 AM »
Just looked at the schematic.  This one is easy:
Remove the following from the board:
C1
C5
C6

Put a jumper between LDR3  (use the pad from which you removed C5 or C6) and R1 (use pad from which C1 was removed.

Experiment with different values for R1 to get the kind of sweep you want.  Play with values of R6 to set the final output level.  *EDIT* You mentioned your are new to this, so I thought I would add larger values of R6 will make it louder.  Smaller values of R1 will result in making it louder too, but it will reduce the "depth".  You will probably want to make R1 bigger and then if that makes the final output too quiet, then make R6 bigger.

The first thing I suggest to do with R1 and R6 is change R1 to a 330k and see how it sounds.


Gotcha.

A couple questions, just for the sake of absolute clarity, and because I'm a n00b.

1.) When you say "remove" C1, C5 and C6, you mean make those capacitors not exist entirely? As in nothing is connected in that position? Do I need to throw something between the mount points to complete the circuit?
2.) You suggested changing R1 to a higher value right off the bat. Does this mean I should ALSO put in a higher value on R6 right away too? Something like 500k?
3.) Foggy on the term "jumper", but I'm fairly certain I can figure it out via context. Just making sure you're talking about simply putting a bit of wire between the connections on those leads.

ace7789

Re: Help!! Morley classic Wah
« Reply #4 on: February 12, 2015, 07:12:55 AM »
Ok, looking at the schematic, I'm putting a couple things together logically. Correct me if I'm wrong. I'm removing C5 and C6 so that the only current that LDR3 is getting is coming from R1. I'm removing C1 so that the only direction current is running from R1 is towards LDR3. Essentially, removing those parts and adding the jump is bypassing like 2/3's of the whole circuit. Is this correct?

GGBB

Re: Help!! Morley classic Wah
« Reply #5 on: February 12, 2015, 09:21:30 AM »
Jumper means connect a wire between the two points. Remove means remove only - do not replace with something else nor jumper.

Ok, looking at the schematic, I'm putting a couple things together logically. Correct me if I'm wrong. I'm removing C5 and C6 so that the only current that LDR3 is getting is coming from R1. I'm removing C1 so that the only direction current is running from R1 is towards LDR3. Essentially, removing those parts and adding the jump is bypassing like 2/3's of the whole circuit. Is this correct?

Not quite. R2 and C2 are still in place so current still passes through the op-amp to the output. R1 and the LDR form a voltage diver / volume control that sits in from of the op-amp.

You should also remove C4 and R5, replace C2 with a bigger cap - something like 0.1uF, and replace R8 with something much bigger like 47k or more. I would also replace R7 with a jumper, and replace R4 with 1M.

The only problem with this setup will be that it may have a slightly low input impedance (will be the total of R1 plus R2) depending on what value you use for R1. This could cause some treble loss depending on what is plugged into the volume pedal. Shouldn't be an issue if there's a buffered pedal before it, but might be with a guitar.
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Transmogrifox

Re: Help!! Morley classic Wah
« Reply #6 on: February 12, 2015, 10:14:10 AM »
Quote

1.) When you say "remove" C1, C5 and C6, you mean make those capacitors not exist entirely? As in nothing is connected in that position? Do I need to throw something between the mount points to complete the circuit?
Exactly.  Snip, cut, desolder -- however you do it and throw them in the garbage can.

Quote
2.) You suggested changing R1 to a higher value right off the bat. Does this mean I should ALSO put in a higher value on R6 right away too? Something like 500k?
Not immediately.  Only change R6 if the max volume output is too low.  The value I recommended for R1 increases input impedance, and sets the max gain to approximately unity.
[/quote]

Quote
3.) Foggy on the term "jumper", but I'm fairly certain I can figure it out via context. Just making sure you're talking about simply putting a bit of wire between the connections on those leads.
Looks like you got it form context.  Just means solder a wire from point A to point B.

GGBB has some good suggestions.  Let me "re-list" to catch all of both of ours:

C1, C4, C5, C6, R5 go in the garbage bin.
LDR3 gets reconnected to the point between R1 and R2 with a "jumper" (wire).  As noted before you can use the pads on the PCB from the removed C5/C5 and C1 as connection points with the wire.
Make C2 into a 0.1 uF
Make R1 into a 330k

Changing R8 and R7 are optional, but these values would be better selected as such:
R8 = 10k or greater
R7 = 470 ohm or less ( substituting a wire is fine too ).

Changing R7 to something between 100 ohm and 470 ohm is good because if your cable is picking up any RF noise (radio stuff) the output of the amplifier can work as a demodulator for AM radio and be part of a "sneak" circuit making the radio noise become audible.
trans·mog·ri·fy
tr.v. trans·mog·ri·fied, trans·mog·ri·fy·ing, trans·mog·ri·fies To change into a different shape or form, especially one that is fantastic or bizarre.

ace7789

Re: Help!! Morley classic Wah
« Reply #7 on: February 14, 2015, 07:00:42 AM »
Cool. What do you think about replacing R4 with a 1M like GGBB suggested?

GGBB

Re: Help!! Morley classic Wah
« Reply #8 on: February 14, 2015, 10:27:10 AM »
Cool. What do you think about replacing R4 with a 1M like GGBB suggested?

It is a minor change that in all likelihood won't make any real-world difference. It provides a bit more headroom for the op-amp to allow a little more gain/boost without clipping, but you probably won't need that much gain anyway. Op-amps are usually biased at 1/2 Vin unless there is a specific design objective in mind for doing it differently. R3 and R4 form a voltage divider to provide a bias voltage for the op-amp. With a 1/1.2 setup and 9V power, the highest possible signal level without clipping you could theoretically get out of the op-amp is 9Vx(1/(1+1.2))x2=8.18V peak-to-peak. Above that and one side will start to clip first. By replacing R4 with 1M, you'll have a 1/1 setup, where the max is 9V p-p. With the gain levels recommended by Transmogrifox, you won't get close to that anyway.
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ace7789

Re: Help!! Morley classic Wah
« Reply #9 on: February 18, 2015, 10:58:16 PM »
Alright, so correct me if I'm wrong, but, while installing this jumper wire, does that mean there's one end of the jumper wire, and one lead on R2 that are soldered on the same pad?

ace7789

Re: Help!! Morley classic Wah
« Reply #10 on: February 18, 2015, 11:55:10 PM »
^^disgregauard that post. Figured it out I think. Attached to the C1 pad like Trans said earlier. I'm gunna be at my rig shortly, I'll let you guys know if it works, or if it bursts into hellfire.

andremanson111

Re: Help!! Morley classic Wah
« Reply #11 on: March 12, 2021, 02:41:04 PM »
Hey, guys

I've been searching for something to do with my Classic Wah (I jsut find it horrible) and came across this forum. So, I decided to do the test.
I tried to do these mods (removing C1, C5 and C6) and placing a jumper. There comes my problem: Where, exactly, do I place the jumper? Do you have any pics? I tried soldering a wire, it did not work. Then tried two wires in the places of C5 and C6 )I don't understand a thing, just tried). After the first wire, it "worked", like, there was sound, but no wah-wah. Then, the second, and... it did not work at all. I mean, when I activated it, it just got no sound. It worked when bypassed. So I guess the problem is the misplaced jumper (correct me I'm wrong). Do you have any pics or could you tell exactly where to place it, please?
Thx!

GGBB

Re: Help!! Morley classic Wah
« Reply #12 on: March 12, 2021, 05:58:06 PM »
Here's a marked up schematic.


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andremanson111

Re: Help!! Morley classic Wah
« Reply #13 on: March 12, 2021, 06:23:11 PM »
I'll try to correct it. Thanks a lot!