Crystal Muff

[rullywowr]

This is a repost of my entry for the Spring contest, however I figured I would post it in the build reports.  This pedal actually came in really handy at a trade show last weekend where I was exhibiting...it's really handy to demonstrate to someone how a pedal's guts look without having to take the cover off.  Even better when it makes sounds and lights up and they can actually play it!

Crystal Muff - perhaps the most 'transparent' muff of all time 
Circuit: Op Amp Muff (using "Muff Opportunity" PCB from www.rullywow.com)

This is a classic "in your face" muff circuit based on the EH Op-Amp muffs circa 1978.  The enclosure is transparent but the sound is thick and aggressive.  Really nails Smashing Pumpkins, Bush, and a lot of other 90's bands' hard-hitting fuzz tones.  Built with no mods, although I have been swapping out the opamps for different flavors because that's how I get down.

For the enclosure, I had an idea to do something original and different, and that was to roll my own enclosure using 1/8" acrylic.  Why?  Why not?

I used the dimensions of a 1590B from the spec sheet and put those numbers as well as the acrylic specs into this awesome Box Generator site (http://boxmaker.rahulbotics.com/).  If you have access to a laser engraver or CNC, you gotta try this out!  I took the PDF generated from the site and used CorelDRAW to draw the artwork and prep for vector cutting/raster engraving.  Holes are aligned perfectly since I didn't have to drill any.  The artwork was engraved from the inside of the box because it "pops" just like on acrylic awards/trophies.   A 30w Epilog laser cutter was used to cut each panel and all the holes/artwork to exacting dimensions.  Had a couple of revisions due to the whole 3mm vs actual 1/8" acrylic debate but it came together great.  The box fits together so tightly that glue is not needed, and the enclosure can easily be assembled by hand like Lego or a jigsaw puzzle.  You can see the interlocking "fingers" on the sides.  A flat-top UV-purple LED completes the enclosure  It is very sturdy, no worries about stomping on it, however it is prone to scratching etc because it is just acrylic after all.













Here is the gut shot...hope you don't mind that I left the bottom cover on


Video:
Signal chain = my lab's 'beater' Kramer Pacer -> Crystal Muff -> POS Princeton SS 10w practice amp

[Leevibe]

Incredible in so many ways!!!

[marmaliser]

WOW ...Just Wow

[jubal81]

Far-freakin' out. Genius idea for a demo pedal and you did a really great job with it.

[marmaliser]

Watch the iron on those big cheap tayda caps

[bcalla]

That is so cool!

[sonarchotic]

Very cool! Very clean looking and original.

[pickdropper]

That looks nice, Ben.  Great execution.

On a related note, I've been using finger joint acrylic boxes for a while for test rigs.  I highly recommend it.  If you wire a detachable header to the switch, you can swap top plates out with various pot/switch mounting schemes.  It works really well.  I even added a top plate with a 4-way spring speaker terminal for when I want to quick check a build. 

I do wish I had found out about the box generating site earlier.  One of my co-workers showed it to me a while back, after I had painstakingly laid out all of the box dimensions and mating finger joints in Illustrator.  Bummer.

[wgc]

This is really cool!!  Totally going to check out the link, and love the test rig idea with headers

[rullywowr]

Thanks for all the kind words everyone.   

It was more of a coincidence that this worked out well for explaining to "non-pedal" people what a pedal does but it does work nicely for that.  Even people who don't know what an effect pedal is/does thought it was cool.  Reminds me of those princess phones back in the 80's where you can see all the inner components and they lit up neon pink/blue.

PD- I also dig the "testing" rig idea with spots for knobs.  Great idea actually.  In a similar vein, I found that some of the first "scrap" pieces I did of the top plate were perfect for wiring up the board and 3PDT outside the box...made it pretty easy actually.  And yes...I was deathly afraid of dripping hot solder on the inside of the enclosure and/or getting fingerprints inside but it turned out OK (phew).  Maybe a tiny nick with the iron on one of those big Tayda caps but who's counting   This probably won't be the last time I do something with a custom acrylic enclosure...have some more ideas.

[pickdropper]

Yeah, there is a lot you can do with acrylic .

Since you have obviously have access to some good tools, check out if you can get a UV curing light.  UV based adhesives are nice with acrylic as they are clearer than cyanoacrylates (no blooming) and setup much much faster than epoxy.  Fast cure epoxy works but usually has a yellowish tint that doesn't look very good.  The optically clear epoxies look better for acrylic but have a long setup time.

[rullywowr]

Yeah, there is a lot you can do with acrylic .

Since you have obviously have access to some good tools, check out if you can get a UV curing light.  UV based adhesives are nice with acrylic as they are clearer than cyanoacrylates (no blooming) and setup much much faster than epoxy.  Fast cure epoxy works but usually has a yellowish tint that doesn't look very good.  The optically clear epoxies look better for acrylic but have a long setup time.

I have this stuff here (Weld On Fast Set #4 Clear, Water Thin, Solvent Cement) which works OK.  I apply with a syringe but always seem to manage to get too much on - which runs down the clean and ruins my project.  That UV stuff you mentioned sounds pretty trick.



Do you happen to have any pictures of your Acrylic PCB testing rig?  I can picture it in my mind but just wondering if you would be willing to share a pic of your setup.

[pickdropper]

Yeah, I actually have multiple acrylic test boxes.  I can take some updated pics later.

I've posted a couple of them in the past.  One is called "the breadbox" and the other is "the puzzle box."

Both of those have colored acrylic.  I'll take photos of the clear one later tonight or tomorrow.

[Leevibe]

Colored, curved acrylic would look cool. How hard would it be to do a curved top? Then you could put a Ludwig badge on it and have a Vistalite pedal. That would be rad.

[rullywowr]

Colored, curved acrylic would look cool. How hard would it be to do a curved top? Then you could put a Ludwig badge on it and have a Vistalite pedal. That would be rad.

Something like this?


I found this tutorial on the subject:
http://makezine.com/2013/02/06/workshop-wednesday-heat-bending-acrylic-enclosures/