Mold Spore Wah tip.

[Ronan]

I would have done that already for you, but, I'm not much into ring modulators, and had other plans for this pedal (I bought it for the big shell with dual pots), so I kept the wah part of the pcb and neatly cut the ring mod section off with a bandsaw. (Umm, sorry Dino ). I labeled everything and drew a rough sketch so I could reassemble the wah section at a later date. The pedal was sold to me as working from ebay, but worked for about 30 seconds, very intermittent, then Dino (digi2t) sent me a schem (the one above), and I got the wah part working great, but I never got the ring mod mod working right. The thin pcb in the pedal is not mounted securely, and suffers flexing when plugging leads into it since the jacks are mounted to the pcb, not the chassis. Easy to see how solder joints will weaken and eventually crack.

I think digi2t has one of these pedals intact, he might be able to answer the question of which pot is the ring modulator pot. Both pots have exactly the same part number 70J1H056F104U made in Mexico, with "MOD POT CLAROSTAT" on the rear cover. If they are a log taper, that might cause you some difficulties, because they rotate in opposite directions during the pedal sweep. There are ways around that, but it depends on the circuit tolerance to a lower input impedance from the pots. They might not be log, I can measure one tomorrow if you like, since they are out of circuit.

[slacker]

There's also an error in the wah section of the schem, R6 and R7 are shown in parallel. Actually its not an error, because the pcb has these resistors in parallel too. An error that never got picked up!??

It's a strange one that, I've got a Whine-O+ which is the same Wha circuit and that has the same "error", I had to triple check when I traced it because I was convinced I must have got it wrong, but those resistors are definitely in parallel. Perhaps it started as an error but they liked how it sounded so left it like that.

[digi2t]

OK, some hi-def shots of the guts;







R28 is now replaced by a Bornes 100K vertical inline trimmer. Bend and solder the 2 leg to 1 or 3, and it fits perfectly into the spacing of the resistor.

I think digi2t has one of these pedals intact, he might be able to answer the question of which pot is the ring modulator pot. Both pots have exactly the same part number 70J1H056F104U made in Mexico, with "MOD POT CLAROSTAT" on the rear cover. If they are a log taper, that might cause you some difficulties, because they rotate in opposite directions during the pedal sweep. There are ways around that, but it depends on the circuit tolerance to a lower input impedance from the pots. They might not be log, I can measure one tomorrow if you like, since they are out of circuit.

The wah pot is VR1, the ring mod pot is VR6. Both are marked as "B", so linear. Having the gears separate a must allow for tuning the sweep range of one, without affecting the other. Note that VR6 is only active when you place the pedal in frequency shift at the pedal mode. SW4 is mislabeled on the schematic, and should read "Freak Sweep". This switch transfers ring mod control between the pedal or the side pot. Also, SW5 is the "Hi/Lo" switch, which could also be considered as Tone.

Insofar as the parallel resistors are concerned, could it be that it's to create a custom resistance that otherwise is not available? I ran the numbers through the parallel resistor calculator, and those two values give me 30.8K.

I tested the inductor, and I get 686.4mH on my inductance meter, so within range of the schematic.

I just had an idea about the twin pot scenario; I could use a Dunlop shell, and with a piece of sheet stainless, make a second bracket for the second pot. I could use an Omeg conductive plastic pot, which is smaller, and more compact, mount it opposite the main pot, and run it above the main pot off it's gear. That would maintain the ability to adjust the gears individually. Insofar as the opposite rotation is concerned, it doesn't really matter since you can just switch pot poles.

[joegagan]

the ability to orient the two pots relative to one another is critical no matter how you do it. that is why dualgangs are problematic for many foot operated circuits.

the parallel resistor thing at the 33k/470k has no basis in electrical reality. 30k resistors are available,even 33k is within tolerance on 10% . there simpy is no logical reason, but i agree, it is like this in my moldspore as well. my theory is that it is an oldtimer wah mod where you simply took the 33k that parallels the resistor, lift the end that goes to the inductor and resolder it to the C of Q1 ( note there is also no parallel r to inductor as in normal whas). it is a very good sounding trick. people in my shop like the mold spore wah better than my modded wahs in several instances.

i also believe the settings for the sweepable cap are reversed. the shaft setting should be the deepest, yet it is the birghtest. i found some discrepencies on the caps on my actual unit vs the schematic values. i think the values were all there but in the the wrong positions.

i have had two of these, the one in the 2008 vids is different than the one in the 2011/12 vids. i no longer own the first one. the serial numbers were in the 400 to 700 range if i recall.

[armdnrdy]

digi2t,

Thanks for the great shots and the info.

I've spent some time last night and this morning figuring out the switch/pot wiring and names. I found the user manual and various gut shots on the net which were helpful in determining what the various switches and pots do.

I did notice the mislabeling of SW4 and SW5. The manual's description of their function didn't make sense the way that they were wired.

Checking out your pics, I see that they changed the optocoupler from the gut shots I have and the schematic. I've come across this type before when I was looking for a cheaper alternative to the Excelitas vactrol after their prices hit the roof. This variety looks like it's housed in an electrolytic capacitor can, complete with the polyvinyl chloride (pvc) sleeve.

http://www.components-electronic.com/product/analog_linear_optical_coupling-11213887534552707600/showimage.html

Also, good idea about running a second pot gear to gear.

Hell...if we wanted to, we could mount a sprocket and use a miniature bicycle chain! Build a better mouse trap.

[joegagan]

oh, sorry, one more bit of sprinkleshine on your parade , digi2t. the 'gear driving a 2nd gear' thing does not work. ( opinion based on trying it). it adds a lot of drag. the additional torque required to move the treadle feels clunky and unnatural. it was pretty bad.

[armdnrdy]

oh, sorry, one more bit of sprinkleshine on your parade , digi2t. the 'gear driving a 2nd gear' thing does not work. ( opinion based on trying it). it adds a lot of drag. the additional torque required to move the treadle feels clunky and unnatural. it was pretty bad.

I was looking at my 535Q last night and I had the thought of putting the ring modulator switch in the heel down position. It looks like there is the same clearance as the toe down position. Just add a felt pad as was used for the effect in/out switch.

The Mold Spore's "foot" pedal allows for this switch in front of the small toes which seems a bit awkward. I think it would be more user friendly in the heel position. Any thoughts?

[joegagan]

it is the question of all time. where to put switches on wah type pedals. i agree, the placement of the ring mod switch is a little, awkward, especially when you consider how high the gas pedal sits. a switch at the backside would have to be low profile if in a crybaby case.

luckily, both of my mold spores worked ok. the first one was refurbd by k segal himself after i bought it. the second one has LED issues, but otherwise works fine. kenny told me to tell you guys that the first thing to check when the ring mod goes out is the max1044, these were sporadic.

[armdnrdy]

Thanks for the info Joe.

I was thinking about reworking the charge pump section with a LT1054. They seem to be much more reliable. I don't see the voltage of IC3's (charge pump) output (B+) listed anywhere. Do you know off hand?

[armdnrdy]

I don't see the voltage of IC3's (charge pump) output (B+) listed anywhere. Do you know off hand?

Nevermind. The schematics are a bit grainy. Upon closer inspection I see that the charge pump is producing a bipolar supply.

[slacker]

B+ is the input voltage from the battery or DC input. If you look at top right of the schematic you can see B+ marked there.
Edit: posted this the same time as your last post.

[digi2t]

oh, sorry, one more bit of sprinkleshine on your parade , digi2t. the 'gear driving a 2nd gear' thing does not work. ( opinion based on trying it). it adds a lot of drag. the additional torque required to move the treadle feels clunky and unnatural. it was pretty bad.

I'll see your sprinkleshine, and I'll raise you with some ingenuity.

Make a second bracket as mentioned before, but use splined shaft pots. Run the two pots, shaft to shaft, and use a splined gear. Share the gear between the two pots. The spline should allow for a decent adjustment differential between the two pots. Not quite "set screw freedom", but close. Besides, drilling and tapping a set screw into these little plastic gears? The structural stength of the threads would be just a touch better than drilling and tapping the same threads into fresh dogshit.

[armdnrdy]

I was looking at my wah to figure out the two pot, one pinion gear scenario, when I came up with a similar idea.

The pinion gear is wide enough to work on two shafts. My wah pot has a flattened shaft. There are also knurled shafts available. The pinion gears come in either style knurled or flattened.

My thought is to cut down the shaft of either style just enough to fit within the confines of the custom bracket and wah enclosure. Done!

This sounds easy enough...just like everything until you have the parts in hand and realize something's not going to work!

[joegagan]

i am sure i shortened the shafts on the ones i did that shared a gear.  i used D hole gears but drilled to round on the half that went into the added pot. also note in my photos each one has a setscrew once the orientation is dialed in. the setscrew is a small woodscrew, threads into the nylon and holds just fine ( pre-drill with a sufficiently undersized hole). i cut the little screwheads off with a dremel saw once they are screwed in.

also, grind a little flat spot on your shaft for the setscrew to hold to. this requires you to have previously dialed it all in ( obvious ).

as mentioned, these two pedals were done in '04-'05  and have been used a lot, nothing has come loose.

[armdnrdy]

After doing some tests, I finally replaced R28 with a 100K trimmer. Increasing the gain of the op amp did the trick. Now I have it dialed in so as the volume between the two modes is equal. It also allows just a bit more of the straight signal to bleed through into the ring mod allowing for more dissonance.

Dino, Joe, and everyone else,

I'm working on two redrawn schematics for this thing. The first one will be a more legible copy of the original. The second one will include a few adjustments. Replace the charge pump with a LT1054, address volume drop Dino is referring to above, correct discrepancies between factory schematics and later units.

If anyone wants to pop in with any information, it would be very welcome.

Dino, I know this sounds like a pain...but is there any way you can check the resistance you ended up with for the trimmer you added in place of R28?

[digi2t]

Dino, I know this sounds like a pain...but is there any way you can check the resistance you ended up with for the trimmer you added in place of R28?

I could, but honestly, I believe a trimmer is the best option here. The "ideal" resistance can vary between 37K and 50K. Why the spread? Because it depends somewhat on how hard you mix in the ring modulator. If you're always heavy on the ring mod, then the volume boost of the ring mod will make up the difference. If you're light on it (like me), and wish the straight signal to cut through more, then you can increase the resistance.

It really is one of those "adjust to taste" things. If a builder wants to use a resistor, then they should test with a 100K pot, and then chose the resistor accordingly. Or, use a trimmer, as I have done. 

[Govmnt_Lacky]

Replace the charge pump with a LT1054...

NO dog in this fight but I thought I would throw a monkey into the wrench...

Correct me if I am wrong BUT, I believe the LT1054 DOES NOT have the same "frequency boosting" capabilities as the MAX1044.  

Does this circuit have Pins 1 & 8 connected on the charge pump?

Food for thought  

EDIT: Looks like the pins ARE connected in the pics from Dino above. 

[joegagan]

i haven't modded or messed with any of mine, it is unlikely i will have time to do so.

but for what it is worth, i have found that for myself and the majority of people who try it, most of us like the ring mod in low doses(mixed low in the signal). a little goes a long way.

[armdnrdy]

Replace the charge pump with a LT1054...

NO dog in this fight but I thought I would throw a monkey into the wrench...

Correct me if I am wrong BUT, I believe the LT1054 DOES NOT have the same "frequency boosting" capabilities as the MAX1044.  

Does this circuit have Pins 1 & 8 connected on the charge pump?

Food for thought  



EDIT: Looks like the pins ARE connected in the pics from Dino above. 

Thanks for bringing this possible issue up. The LT1054 does have "frequency boosting" capabilities. You place a small value cap (5-20pf) between pin 7 (oscillator) and pin 2 (cap+) and the frequency is raised.

I've had great results using the LT1054 to create bipolar supplies. I've never heard of problems associated with them unlike the MAX1044.

[armdnrdy]

i found some discrepencies on the caps on my actual unit vs the schematic values. i think the values were all there but in the the wrong positions.

Do you recollect any of the areas where there were discrepancies?