My May-Dec 2015 builds wrap-up

[midwayfair]

Usually my Madbean reports are more comprehensive than the summaries I post elsewhere, but I was a bit more lazy the last few months.

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This started out as an adaption of the Tube Driver for a 1590A, but turned into something more like "in the spirit of" instead of a direct adaption, but I reeeaaaally like how it came out overall, halfway between a booster and an overdrive but still capable of some pretty gainy sounds. The project thread is gone, probably the only major thing I lost in the forum crash -- I didn't make a Google Doc for it, but Thomas retained a pretty good amount of the text in the PCB documentation: http://diy.thcustom.com/jon-pattons-cruz-driver/

And here's a quick demo I recorded as a warmup before going out to play: https://dl.dropboxusercontent.com/u/9878279/Test%20recordings/Cruz%20Drive%20demo.mp3

He didn't have any instructions for the art beyond having labels for the controls, so I named the build after him and put a red roadster on it. vroom vroom!

This was a fun challenge, and it came together pretty quickly once we identified what would work well with his amp at home (a Bruno S100, holy crap) and on a big Fender. At home he just wants a "more" button, so I had to make sure there was a flat dirty boost in here somewhere.

I replaced the op amp buffer + inverting drive stage with a MOSFET booster, and replaced the tube stages with with FETs in the normal manner. Note that the design inverts phase, which the original did, too.

I moved the tone controls to put it before the last gain stage because otherwise it was just insanity on the gain levels. It's already pretty nuts even with all the cuts in front of each stage, but this gives a lot more control over the overall clipping. The tone control and switch are really what make this cool. (Thanks to Cody and Thomas for tossing around some ideas, even if I ultimately went with something different.) Really I'm just repurposing once again the tone control from my Sakura amp, but everything worked out just right for me to get a third mode out of this one and to have a usable bass control.

1) The bass control just shaves off some low frequencies below about 400Hz. It's is a shelf filter, so the bass isn't gone, just deemphasized, and at 5:00 the cutoff is at 18Hz.

2) Treble/Tone control: This is based on a version of the Big Muff tone control, with the resistor to ground for the low-pass removed. A lot can be done to radically alter the behavior of the tone control just by varying C9, so that's what the switch does. R8 is a small resistor (I picked 2.2K) to limit the ultimate range of the tone control so that it doesn't turn into a full low-pass filter, but it can be omitted for some very very dark settings in the scoop mode. I just don't like tone controls that bottom out.

Three modes:

a) Mode 1 flipped to one side: Flat treble at ~3:00 on the knob, at 5:00 a VERY tiny boost in the treble above 700Hz, and CCW cuts the treble at that same frequency, like a see-saw. With both tone controls down, it'll form a mid hump right around the middle of a Fender amp. (If I were to leave off the switch, this is what I would use as the stock mode.)

b) Mode 2 in the center: At ~3:00, the mids are boosted by about 3dB centered ~1KHz (bass and treble are flat). There's again a slight treble boost at full. CCW, the treble gets cut at 2KHz, so it's milder than mode 1, for just shaving off the harsher harmonics created by the distortion. This mode was a freebee on the layout by adding one capacitor, so I saw no reason to omit it. It's not as dramatic as the other modes, but it will usually sound flatter when there's a lot of distortion present.

c) Mode 3 (flipped the other way) has a mid scoop at ~250Hz for added clarity (this is the "mud" frequency for guitars, so it's a good frequency to cut). CCW, the treble is cut very deeply, which allows for bass boost with the bass at full and the tone turned down, or a treble boost with the tone up and the bass down. But with the treble and bass at about 9:00, it's back to a nearly flat response but with the gain cut a lot, for some "mostly clean" boost settings.

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LEDman vs. The Cads -- kgull's Mutron II PCB.



Before I get into what a mess I made of things with this build: Major kudos to Kgull for an amazing layout.

I had one problem after another with this build. I fired it up the first time and my rate indicator blinked but not the one for the effect. Scratch my head, poke everywhere, remove and replace some chips ... woops put a TL in backward and popped an LT1054. Crap. Toss it. Poke around some more, eventually get the bright idea to remove the LED and test it ... oh, it's a dead LED. Toss it.

Replace the LED. Something not working now. What the heck? Oh crap, I mixed up the leads on the power and ground when I plugged them back into the breadboard. Popped another 1054. Replaced ... oh crap, I had popped the Zener a minute ago, didn't I? Replaced it.

Everything's finally working in the LFO. Plug in all the audio chips ...... only dry sound, no phasing. Well that's weird. Do some audio probing, figure out that one of the chips must be dead. Unfortunately, I'm out of TL072s, and I only have a couple TL062s. Replace the chips one by one until I get audio at the phaser section ...

Put one in backwards. Smoke from the 1054.

ARG. Replaced.

Go to box the thing up, and here's where it gets really stupid:

(a) I wanted to use up this box, but I had already drilled it. It's got an extra hole. Hey, I'll just add a dry lift for a vibrato mode. More on that in a minute. Annnnd my rate LED won't reach.

So I desolder the rate LED, add legs ... resolder and ...

What the? Now the rate LED isn't blinking. I pull it and test it ... still works. Look all over the board. Eventually (not even lying -- like a half hour to find this) I find the lifted trace, after scraping away a bunch of solder mask and being completely unable to find the trace to pin 2. Resolder ... still not working. Huh. Somehow managed to blow the LED WHILE TESTING IT. Replaced. Finally everything's working again.

(b) The Lumin board is the only optical bypass that will fit. And it's masked on both sides ... so of COURSE I put it on the switch upside down. And I don't figure this out until after I had wired everything backwards. But I get everything soldered up, test the bypass, everything works.

Oh, I forgot ... I wanted polarity protection. Desolder the power wire and install a 5817 between the jack and the switch PCB. You might guess where this is going ...

Plug in ... nothing. Not even the bypass LED. How is that possible. 0v on all the power pins. What the hell?

Eventually -- again, not even joking, at least a half hour -- I figure out that I'm getting 9V at the input on the board because my probe is hitting the lead of the diode itself, and I see that I lifted the pad for the power trace on the Lumin. Desolder the diode, use a new one and go to the other side of the switch (thanks for putting two pads, Rej & Jason!).

Finally ready to go.

With that much troubleshooting defeated, I felt a bit like a superhero, so I went with a comic book theme (Baltimore Comicon is next weekend, too, though I'm not going).

If you don't get the pun in the name of the pedal, most photocells use Cadmium Sulfide, abbreviated as "CdS." So, the enemies are the cads, crowding around LEDman.

As for how it sounds, it's different enough from the other phasers I've made that I think it's worth a build. (I prefer the Stage Fright overall for intense phase, I think.)

I used Smallbear's 9203 photocells. These have a high dark resistance; I found that to get the most out of this pedal, having the LED go darker gave a more pleasing sweep on the treble side of things. I actually used a 2K trim for the LED limit, and it's dialed almost all the way up; I also have the 10K balancing trim past noon. The sweep sounds a little lopsided no matter what, but this gives a really wide sweep and seems to get the most out of the circuit.

My one mod was the dry path lift, to create a pitch vibrato effect. I don't think this was worth it. It's a subtle difference with the Regen fully CCW and sounds kind of interesting -- but it's basically unnoticable at higher regen settings except that a very small amount of extra bass comes back in when in phaser mode. It's possible that there was a better way to implement the mod and maybe lifting the Regen as well would have helped make the Vibe setting more noticeable, but I couldn't do that with only a SPDT, and I couldn't fit a two pole switch.

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Verified the new Cardinal V2 PCB.

It's been a long road, but it's finally here! I probably spent more time overall on this design than anything else, and the new project has been improved in pretty much every way from V1. Josh's new layout is pretty killer, too. The new PCB is slightly smaller than V1, so now it will fit with the Optotron for those who want to use optical bypass (which I highly recommend with FET-input effects). The pots and switch are all board-mounted now as well.



Important Note: there was a rendering error due to an incompatible part between my Eagle library and Josh's on the prototype PCBs. The final version of the PCB has the Vactrols rendered properly and they will be installed with the writing up. (If you were wondering about the solder burns on one of my caps and one of the vactrols, that's the explanation ...)

You'll also notice that, klutz that I am, I drilled the blinking LED on the wrong side of the enclosure. Derp. Don't be like me, kids!

Otherwise, it came together very quickly (despite the need to match a couple components, it's way easier to dial in the effect to be perfect now). It's my standard art, which everyone is probably sick of at this point, though I did have some fun with graphic labels on the knobs instead of werds.

There are some extra spots on the PCB for optional components, including a +6dB boost for the first stage and optional miller caps for the second stage, which I leave off on my builds.

Here's the demo:

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A Hamlet delay with an oscillation switch and the tone trim external -- part of a trade with the next pedal for a pearl drum kit that needed some work. He insisted on a battery even though I explained that the pedal would easily drain one in a few hours. The last of the black PCBs. I'll miss them!



A plain-Jane Orphan Fuzz. He wanted mostly unadorned enclosures, but I did sneak in some silver strings on the "O" to make it look a little like a harp ...


Another Hamlet, for local guitarist Quinton "Q" Randall. That's him inside the Q.




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Built for a (repeat!) customer. I took the fuzz and bias controls from the Rust Bunny, changed the tone control to affect the bass only (from the Vox's original massive bass cut at 1KHz down to 144Hz with the bass all the way up), and built it up on perfboard with a pair of germanium transistors (a Russian MP38A hfe ~75 in Q1 and a US 2N388 [I think that was the part number] ~52 in Q2) with gain buckets similar to reported values from some vintage units. The relatively high capacitance of the Russian transistor (which is part of what makes them sound so good) helps smooth things out for most of the distortion to keep it from getting way too harsh, and the relatively low capacitance of the 2N388 kept it sounding very edgy. Although the circuit looks like a Fuzz Face, it sounds different and doesn't clean up as fast with the guitar volume, which is pretty typical of having the gain buckets "backward" -- if I were to swap the positions of the transistor pair it would react just like a Fuzz Face, but multiple posts I found about the Vox TB confirmed that the second transistor was lower gain than Q1. It also isn't quite as dirty as a fuzz face overall.

I made it on perfboard because I would have been jumpering half the component slots on the Bunny's PCB, so this just seemed tidier.

I really like how it turned out and I kinda want to make myself one.

Another customer build:



Tetragrammaton. A Snow Day and Cappuccino (percollator clone with extras) 2-in-1 for a customer in North Carolina. He named it and provided some usual bits of artwork he wanted in there.

I was particularly happy with the way the sky came out -- I did layers and then used thinner to get the swirl effect. Diodes for the Cappuccino are 1n695 (odd) and OA126 again, but there's also a diode lift. The Snow Day was build on the Madbean board with some compromises between my original and Brian's improvements to the circuit.

I accidentally cut the wires a little short on the Snow Day's power, and I couldn't get the wire back through the soldered hole, so it looks a little messy in the corner, and I had to flip the bypass PCB upside down to get the LED in the middle, but otherwise a straighforward build. The Snow Day board was a leetle bigger than I expected, so I had to do "portrait" instead of the "landscape" orientation I usually use for 1590BB 2-in-1s.

This is a pretty killer combination. He plays garage rock type stuff so I think he's going to really like the OA126 setting on the Perc stacked into the no comp setting on the Snow Day.

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Fallstaff with a beard for a customer. Very slight tweaks to the original frequency cutoffs (I updated the build document), and a black glass CV7003 that I've been holding onto for a while.

[Leevibe]

Still taken with the Cardinal V2. Can't wait to do one of those. Lots of music in that little box. And that Snow Day. That's my favorite of your hand painted pedals. It's just cool.

[Tremster]

That Orphan battery protector!!!!!!

[selfdestroyer]

Vero + hand painted = DIY at its finest.

Keep them coming Jon, I love seeing your builds.

Cody

[kgull]

That Bunny Bender is freaking adorable. Completely missed it first time around.

[juansolo]

Bunny's too tight to mention, as a ginger singer once said

[nzCdog]

Bunny's too tight to mention, as a ginger singer once said