Wilhelm Scream Drive (PPCB Discrete Overdrive)

MichaelW

Well-known member
Build Rating
5.00 star(s)
So a while back @Robert released a couple of "discrete" overdrive projects. The "Fingers" and the "Wilhelm Scream".

This was pretty early in my building and I thought "discrete" meant that the pedal knew how to keep a secret......... :p

I read @jeffwhitfield 's build report of building both of the above pedals and I was inspired so I decided to build the "Fingers" overdrive first.

I had some self inflicted noobie dumbassery involved with that build and it took me two boards to get it working. It was also my first experience with SMD JFets but I don't think I can punt that as an excuse. It was part of the learning process but I wound up with a working "Fingers" and loved it! Very cool drive and I loved it for a low gain sound.

But I never did get around to building the "Wilhelm Scream" for some reason. Until I recently grabbed the board during one of the sales.

Both the Fingers and Wilhelm are discrete in that there are no opamps and the circuit is powered but the constituent parts of what makes up the opamp circuitry. So lots of transistors and such.

Pretty interesting project doing it this way.

If you take a closer look at the schematic for both of these, you can quickly see that the Wilhelm Scream is essentially a straight up Tube Screamer, just without using an opamp. The Fingers on the other hand, looks more like a Timmy derivative to me.

They have some overlap in how they sound but there's also some differences as well. As I mentioned, the Fingers is one of my favorite low to medium gain overdrives. It sounds thicker than a Timmy does to me and it has some really delightful harmonics in the gain structure.

The Wilhelm Scream sounds pretty much like a YATS. There's some "slight" differences when compared to my stock LGSM/TS808 but I find it interesting that so much is made about the opamps in a YATS and here was a pedal with no opamp sounding pretty much the same.....:ROFLMAO:

Both of these pedals are recommended builds if for nothing else than the novelty of a discrete circuit. But they both also sound great!

I recorded a demo comparing the Wilhelm to the Fingers to my LGSM.

And there's an old demo I did of the Fingers in the context of a song (Warning Steely Dan content, click the link at your own risk...:))

I used another of the cool matte pink enclosures from SBP. I wish I had known about these when I built my Strawberry overdrive (Snozzberry), it would have been the perfect color scheme for that pedal!

IMG_5876.JPG

IMG_5875.JPG

 
That's a great looking build and sounds great too. I'm curious why you used the SMDs and was there a place to solder them in or did you rig something up? Also, do you do your 3PDT wiring in the enclosure or out? That wiring and soldering looks perfect.
 
That's a great looking build and sounds great too. I'm curious why you used the SMDs and was there a place to solder them in or did you rig something up? Also, do you do your 3PDT wiring in the enclosure or out? That wiring and soldering looks perfect.
On most of @Robert 's boards there are both pads for SMD's and thru hole for some of the harder to find TO-92 transistors. (E.g., 2N5457, J201, etc).

I use Buss wire. I solder them into the board first. Then I lower the 3PDT breakout board on to the wires, solder and trim. Nice and neat.
 
That's a great looking build and sounds great too. I'm curious why you used the SMDs and was there a place to solder them in or did you rig something up? Also, do you do your 3PDT wiring in the enclosure or out? That wiring and soldering looks perfect.
I love getting on my soapbox about SMD transistors, so I will do it now :) If you can, do. The variances are better (less), and you can get them from verified supply lines a lot easier.
 
I love getting on my soapbox about SMD transistors, so I will do it now :) If you can, do. The variances are better (less), and you can get them from verified supply lines a lot easier.
Got any tips for soldering these? I did the ones on my Protoboard but it was a big slot and still hard to do. I did such a terrible job I was actually surprised it worked but it did :)
 
Got any tips for soldering these? I did the ones on my Protoboard but it was a big slot and still hard to do. I did such a terrible job I was actually surprised it worked but it did :)
What works well for me is tinning the solder pad on the PCB, then I hold the transistor with some tweezers and solder the single leg side. I just press the leg into the tinned pad with the iron and wait until it takes hold. Then the component is held in place and I can do the other side.

If you have pads for through-hole as well (like the Wilhelm), then you can test with a component tester that you've soldered it correctly using the through-hole pads. I still do this.. (though it's usually because I have a mis-trust of my own component footprints).
 
Got any tips for soldering these? I did the ones on my Protoboard but it was a big slot and still hard to do. I did such a terrible job I was actually surprised it worked but it did :)
The method @szukalski mentioned is how I do it as well. I personally use a fine tip conical soldering tip for all my soldering (except for the back of guitar pots, where I'll use a chisel). But with the fine tip, heat up one of the pads and put a very small drop of solder on it.
Then "carefully" with a set of micro tweezers place the component in place and touch the solder tip to the blob of solder you just put down. The leg will "sink" into the blob. Once thats cooled off you can solder the other legs.

Couple of tricks. Keep your tip VERY clean for these. I'll wipe it clean on a brass scrungee for each leg. Don't use too much solder, a micro drop is all that's needed.

Learn not to squeeze too hard with the tweezers when picking up the transistor. They tend to want to jump out of the tweezers and they go flying across the garage, you'll never find it again on the garage floor.....heh....ask me how I know.....

And finally, like @szukalski I always test for continuity with the thru-hole pads with a DMM just to double check my soldering work. It's an easy step to get out of the way.
 
Another thing to help SMD work is to use finer solder-wire, .5 instead of .8 or 1.
I've seen it offered as thin as .3 , but I think the .5 I have is thin enough for me.




RE DEMO:
P-90 L❤️‍🔥VE !




I've been watching the Clone Wars and the Wilhelm Scream was in several episodes in a row — I'm only on season 3, so I'm not going to go back and see if it's in every episode, but I'll be listening for it in every future episode I watch.
 
Back
Top