Build Your Own Clone Message Board

Here's my take on a fairly basic two-transistor, inductor-based wah. The only "mod" is that the "Q" point is adjustable via trimmer (or it could be a standard pot as well). I changed a few values from the classic set, but it's basically just a wah.

Yes, there are already a ton of wah layouts out there. My intent with this particular project is a "stuck wah" with a board-mounted Wah pot and a trimmer for the Q adjustment. I see a lot of these types of circuits, but most of them don't have an inductor, which I think is where a lot of the mojo leaks out into your tone. But I will also add some drill hits (read: holes) for those that may want to use this as a drop-in for a Crybaby or Vox treadle.

I plan to release this as an open-source project, so if you guys could give a look at my drawing, that would be great. I think it's right, but I tend to make mistakes in schematics (just as dcountry).

Thanks!

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TightCamera - Gear Reviews

Nice SRV reference to the name

I'd be in for a fixed variety fur shur.

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Yes the schematic looks good to me. Basically a Clyde McCoy style wah, with the different Q set up like you mentioned, an appropriate sized input resistor for true bypass and the IMHO needed addition of power filtering and reverse polarity protection.

Any chance of adding an op-amp based fuzz friendly buffer to the board, like something similar to the Fox Rox one? That would make the project go from amazing to perfect as far as I am concerned.

-Dan

I had a fair mess about with this idea a while back with the Freq Box I posted on here somewhere. That used a twin t filter wah rather than the inductor type but I played with that idea as well. The FB went through a couple of versions but nothing I was ever happy with in the end.

The problem is that with the wah as it is theres a lot of travel through the whole pot rotation, and a lot of that is pretty useless bass frequencies. Most wah treddles have a limited action on the pot and yet its still a pretty small are of that we tend to concentrate on. My next avenue of experimentation along this lines was going to be with EQ filters. If you can narrow the bass area and spread out the treble frequencies it will be better IMHO

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To err is human, blaming someone else shows management potential

I can look into that. Thanks for the suggestion.


The good thing about these manual wahs is that you can just zero in on what frequency you want.

Hmmm. Maybe it would be cool to have a second wah pot with a toggle to swap them out. That would offer a choice of two sweet spots.

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Here's my layout for the above posted schematic:

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Yo, DB. Is this what you are talking about?

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TightCamera - Gear Reviews

I like this idea for sure. I'd be in for a few no doubt.

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Yes exactly! Thanks for getting to that so quickly!!! I have heard really good things about that buffer. Right now I have a simple Jfet buffer in my wah (a perf build from scratch but basically a modded out McCoy) and it does the job but is just meh. Supposedly, the above buffer kills less of the fuzz mojo.


-Dan

Dan. Build. This. Now.


Then see this
viewtopic.php?p=268128#p268128

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Haha yeah I really need to. I've had that layout on the to do list for a while. I am really itching to start building again, it's been nearly a year since my last build. My apartment right now is not very conducive to DIY, but I am out of here in 2 months YAY! I bought some vero but have yet to use it, I need one of those trace cutter thingies. But I would imagine it goes much quicker than perf does.

I just may have to grab my wah and do some modding anyways tho, the last time I played it I was just not feeling it. And now I really have the itch!

-Dan

Are you in law school?

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Yes and no. Typical lawyer answer...lol. I graduated from University of Florida's law school in May of 2011, and passed the bar last summer. But I went to University of Miami this school year to get a masters degree in tax law (called an LL.M. in Taxation). I just graduated from that program this May, and now I just need to find a job! I really want to practice in Trusts & Estates and Probate law, doing estate planning. So it is not all tax stuff all the time, but there are many tax considerations that need to be made clear to the clients. Often you can accomplish exactly or almost exactly what the client wants and avoid a large tax bill at the same time, legally of course.

I am hopeful that I will find a job sooner rather than later and in the practice area that I want. Out of the 38 people in the tax program there were only 4 who graduated with a job, not counting about 3 people who were already attorneys and had been for a long time that are going back to their firms.

-Dan

Tax law, eh? I used to work for the NY State Society of CPAs, and we had some members that were also lawyers.

When you get some time, you can try to explain straddle transaction to me.

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Really love all this, having a Fox Rox style buffer in the wah layout would be killer, that buffer is seriously awesome.

It would also be great that the pcb could accept «mojo sized» components, for the fishies and what not...

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That's killer man. Dry but awesome Good luck as you've put the time in.

Sorry for the derail CJ.

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Thanks guys, I will let yall know when I find a job.

@CJ ugh the dreaded straddle transaction...my Partnership II professor is retired from law now (owns 3 restaurants in DC) but was a big deal in the corp tax world back in the day. He told us a 1 hour story of a straddle transaction he was involved with, still makes my head hurt thinking about it. Luckily the stuff I want to do is not even in the same neighborhood!

Sorry for the derail as well.

-Dan

Hey CJ do you mind if I post what components you would sub if you wanted to make this layout close to a RMC Wizard Wah clone?

I just modded my perf wah to very close to Wizard wah specs last night and I love it, Teese was really on to something there. Just need to perf up the buffer and I am good to go.

-Dan

Dan, what trannies did you use for your wizard wah?
Ive built bajamans version and it sounds fantastic

I don't see what that wouldn't be okay.

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OK cool!

@KunFuz: I used BC 337 trannys b/c well, I had them in my parts drawer and they were the highest gain of all my BC varieties. Using my DMM to measure Hfe: Q1 was about 416 and Q2 was about 417. Mine isn't an exact Wizard Wah, I have a 4u7 N.P. 'lytic in C2, my R3 value is higher, my R1 value is a little higher, C3 I have a rotary switch with 6 different cap choices, and for Q I have an external 100k pot with a 33k resistor tied to one end with markings on the enclosure for 33K, 47K, 68K, 100k, and 133k. What Q values do you like? I have found that 33K is only good for rhythm playing, that 68K is best for lead playing, and 47K is a very good middle ground when you will be doing both. 100K is useful but requires a more controlled foot on the treadle, more play in the middle and less to the extremes IMO.



Below all components are referenced to CJ's schematic and layout in this thread.


Easy subs to get you to 95% correct Wizard Wah Values:
C1 = 15n
C2 = 6u8
R2 = 1k6 (but this is rock and roll, it's close enough already IMO)
C3 = 15n
R3 = 360r (I used 430r, the lower this value the more gain and bass in the circuit)
R6 + Q Trim = 68k (the trimmer will be set to almost full resistance, measure for 46k between lugs 1&2 before you install the trimmer and mark it with a sharpie)
Q1&2 = BC239B (others will work)



To go really crazy and get even closer you will have to connect some components on the top side of the board where there are no solder pads. This may or may not be worth your effort, as far as contributing to the sound I would think the first mod is the one to do if you do not want to do them all:

10pf caps between base and collector: use sockets for the trannys!
For Q1 take one end of the 10pf cap and wrap it around the pin of the socket for the Collector (the one on the right), solder it to the socket, then solder the socket in place. Take the other end of the 10pf cap and solder it to the end of R2 that is further from the edge of the pcb.
For Q2 take one end of the 10pf cap and wrap it around the pin of the socket for the Collector (the one on the bottom), solder it to the socket, then solder the socket in place. Take the other end of the 10pf cap and solder it to the right side of R8.

Power filtering: connect a 1k5 resistor in series between your +9v on the DC jack and the +9v in on the PCB (I think that is too much of a voltage drop, so something smaller is fine even down to say 47r etc.)

Pull down resistor: 4m7 is used in the Wizard, 1m or higher is fine. Solder one end of the resistor to the leg of R1 on the input side, solder the other leg of the pull down resistor the leg of R3 closest to the edge of the board.


Hope this helps somebody, if anyone has questions just ask and I will try to answer.

-Dan

I ordered a set of protos for the simple wah first posted. It works! But...my Eagle part for the inductor is sized all wrong, so I can't get the inductor on the board without some serious wackiness. Doesn't work with Fasels either. But I have two of these boards left, so if anybody wants one of these sort-of-messed-up PCBs, just kick me $1 to cover postage and you can have one (or both).

I have fixed the inductor part and tested it with a paper printout. Should be good to go.

I also updated the Buff-Wah. The "Input" control on the buffer is a trimmer, and I added an on-board DIP switch to change the value of C3. Apparently, this cap is the "primary determiner of the center frequency of the wah effect. Changing its value moves the whole wah sweep range. Bigger values move it down towards bass, smaller values move it up."

I got the info from here:
http://www.geofex.com/article_folders/w ... m#basicmod

The values on there now for the change to C3 are just suggestions. I don't know if changing from 10n, 20n, 30n is really a big effect. But these values could be anything to afford as wide or narrow of a value change as you might want.

I may order a few boards for this. But before I do, are there any other mods you guys would suggest? I'm trying to keep the board a har smaller than 5cm x 5cm, because that's where the good pricing is on the Chinese PCBs. Its' close to that now, but there is a bit of room for maybe another small mod.

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Function f(x)
TightCamera - Gear Reviews

How much for the 2 effed up protos shipped to your favourite swiking Fez?
Have a pile of ok inductors I can attach
The great inductors go in my REALZ wahs