MadBean Polytrog

[dawson]

You guys, I just finished testing/calibrating this build and I'm seriously impressed by the envelope function.  Obviously anything EHX + MBP is bound to be good, but this circuit is so much more than I was expecting.

It's been described as a phaser sweep controlled by an envelope.  That's exactly what it is and the demos sound great, but until I got in there touching and feeling around myself I couldn't really imagine what the interaction would feel like.  You've just got to get in there.  Don't take anybody's word for it, you've got to get in there yourself and let it swallow you up.  I think that's the only way to know why we're all at a loss for proper explanation.

The LFO sounds pretty good too.

Here's my build- all values stock with the voltage tuned to 6.7V.  I gave some lower values 6.3V-6.5V which were quite whacky and fun but in the end I came back to the original sound.
The faceplate was drawn up in Adobe Photoshop and etched into the panel with ferric chloride.




*I need a bit more practice with those skinny-legged 1/8 watt resistors- I didn't realize my fillets were blobbing out until far far too late.
*I also could've used some smaller electrolytics in there next to the vactrols but I was able to make everything fit.
*Knobs look rad, but will be replaced eventually by a set that I can actually decipher from where I stand.




As stated in Brian's build doc's, a whole lot went into getting this circuit modernized and shrunken down for our DIY pleasures, and I want to join with everyone else who's built this circuit to thank MadBean for the loads of effort, expertise and talent that went into this PCB.  It's truly a work of art.

If you're wondering WTF is wrong with this guy who thinks it's okay to build upside-down pedals with no pants on, this thread may answer a question or two:
https://www.madbeanpedals.com/forum/index.php?topic=32053.0

[blackhatboojum]

All hail the schmorg!  I'm in awe every time you add something to that innovative monster.

[Thewintersoldier]

Dude, while we all know the etch and visual representation is always bangin when we see Dawson, the build quality, cleanliness and execution of the board truly fucks. Really stepped it up here, really strong work. Color me impressed!

[jimilee]

Daaaammmn that's killer. I really need to build mine.


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[dawson]

All hail the schmorg!  I'm in awe every time you add something to that innovative monster.

Thanks, Clinton-
Won't be long until you see some familiar 2399 chips show up!

Dude, while we all know the etch and visual representation is always bangin when we see Dawson, the build quality, cleanliness and execution of the board truly fucks. Really stepped it up here, really strong work. Color me impressed!

Aw, shucks, Chris, thanks-

*Most of the credit goes to EHX and Brian with his super sexy build doc's- I'm just happy to be here assembling!

Daaaammmn that's killer. I really need to build mine.


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You haven't built yours yet??
As our resident phasor phanatic you must correct that ASAP!

[zombie_rock123]

Man that's pretty! Inside and put. Love the etch, so crisp! What do you use as the .. etchant..  blocker?

[dawson]

Man that's pretty! Inside and put. Love the etch, so crisp! What do you use as the .. etchant..  blocker?

Thanks!
To be honest, I feel like my etching results have been on the decline for over a year and I haven't been able to isolate which variable is screwing me..
Based on past work, I'd grade this etch a 'C.'



My etching kit consists of:

Brother monochromatic laser printer HL-L2350DW.

PCB transfer paper:
https://www.amazon.com/gp/product/B07GLGL2CX/ref=ppx_yo_dt_b_search_asin_image?ie=UTF8&psc=1

Those nice blue shop towels.

Hand-me-down clothing iron that was about to be thrown away.

The cheapest nail polish available- I prefer bright colors for contrast.

Tiny little paintbrushes for touching-up the mask with nail polish.
https://www.amazon.com/gp/product/B083QB8YPK/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

Electrical tape for masking sides of enclosures.

Disposable gloves.

Ferric chloride for etching.

Acetone for cleanup.

Baking soda for disposal.
*I actually have all of my used etchant stored, but I think it can be neutralized by baking soda.

Olive oil.
*May not do anything, but I've convinced myself it adds a layer of protection.  First-pressed adds mojo.

[harryklippton]

I for one would love to see a tutorial on how you do the etching, not that you need another thing to do

[Bio77]

Looks awesome!    Some more Schmorg, please!

[dawson]

I for one would love to see a tutorial on how you do the etching, not that you need another thing to do

A long-time goal of mine has been to start making videos.
If I can ever actually get myself started on that, etching would be a cool video to make.

This is the video that got me going a few years ago:

*There IS already a great etching tutorial on this very forum written by a builder much smarter with chemicals than me.  I'll link it here if I can find it.

Looks awesome!    Some more Schmorg, please!

Thanks, John-
I'll try to keep them coming!

[harryklippton]

I'll be sure to check out the video you linked thanks. I'm sort of curious to try etching but only sort of

[Paradox916]

Of the poly variety..... excellent build and super


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[jimilee]

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[jessenator]

This build takes me back to my Eurorack days ...all 365 of them. Very well done inside and out!

THE BURNINATOR

Trogdor's 20 years old now

[jimilee]

This build takes me back to my Eurorack days ...all 365 of them. Very well done inside and out!

THE BURNINATOR

Trogdor's 20 years old now

Feels like 30. Geeeezus I'm old too.


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