Rotten Pineapple Komp

[mrclean77]

-Never really been a fan of compressors, but I am digging this one. If I built myself one, I would likely leave off the bloom, but I'm admittedly a fan of simplicity (or maybe just a simpleton, lol).

-Third etch using Cody's tutorial. I was so scared to try etching. Not so much scared of the chemicals, just that I would really flub it up. I feel am getting better. It's hard to tell how intricate of a pattern/design you can get without goobering up the mask. Also, being patient/easy on the pressure when removing the paper is an art. I will forever use my iPhone charging cube as a sanding block....seriously.

-When coming up with an art theme, we were both kinda stumped as to what to do for a compressor. I strongly pushed for lewd n crude. He said he liked pineapples, so....I like the colors a lot more than I thought I would. Also, the smallish, anodized knobs from Mammoth are pretty nice.

-Feel free to suggest a free photo hosting site that doesn't have eleventy pop-up ads a second, like Photobucket does currently, rendering it all but neutered when trying to grab a few pics.....Grrrr.

[midwayfair]

That really looks outstanding.

[jimilee]

That looks really nice


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[Bret608]

I like this a lot too! I've got one of these boards waiting to be populated, and this makes me want to go ahead and get it built.

[Boba7]

Nice work! Really like it! I've never tried that comp, I'm curious about it

[selfdestroyer]

That etch came out fantastic. I have yet to do any multicolored stuff with the fear of messing things up. You pulled it off perfectly.

Yet another has embraced the iSandBlock by Apple. lol

Cody

[Philthy]

awesome work

[mrclean77]

The iSand block works perfectly! I think my main issue w comps in the last was getting em set up, then being bummed when I turned it off. This one seemed like it could handle smoother stuff or chop off the ends for jazzy control.

[bluescage]

Nice!!

[bcalla]

Great etch!

[m-Kresol]

sweet build. the etch turned out really good.

[Aleph Null]

The etch looks great!

So....what does the "bloom" knob do exactly?

[nzCdog]

cool.  just cool.  great etch and theme.... makes me think of stomping on rotten pineapples tho haha. 

[mrclean77]

Thanks again for the comments, folks - this was a super fun build and has helped me decide on etching in the 'etch vs label' decision when it comes to some upcoming stuff I'm making for myself.

The etch looks great!

So....what does the "bloom" knob do exactly?

Check out the Rotten Komp build doc for the schematic/explanation. It affects the low end and headroom - to my ears, it adds s good bit of volume. Not sure if I'll take the time to get this guy on the breadboard, but again, if I built one for myself, I'd leave it off. Also will mention again, though, I'm a compressor dummy, kinda.

[midwayfair]

So....what does the "bloom" knob do exactly?

It's the attack control.

The attack time constant of an envelope generator is calculated similarly to the decay.

The decay is related to frequencies, actually. The calculation for a corner frequency in an RC network is

2Pi*r*c.

R is resistance (in Ohms), c is capacitance (in F), and I hope we all know what Pi is. (If you're curious why Pi is involved, it's because we're dealing with sin waves.)

In the envelope from the Rotten Comp, the C is C10 -- a capacitor that stores DC after the signal is peak-to-peak rectified by D2/D3. The R is the resistor in parallel with the capacitor, which drains off charge at a specific rate.

Hmmm, a specific rate ... well, it shouldn't be any surprise that our decay will end up being a length of time (that's what we wanted) ... and that note frequencies are also measured in a length of time. When you run the calculation, you'll get a number of seconds it takes for the capacitor to discharge. In this case we end up with 100mS.

The attack is related to frequencies, too. Whereas the decay is a high pass filter, the attack is a low-pass filter. It looks just like your basic treble cut. If you squint at R9, you'll recognize that it's forming such a filter with C10.

You can calculate the attack from the same basic equation, but the resistance in parallel with the capacitor is in parallel with the attack resistance, so 2Pi*(R1||R2)*C. R9 is only 22R, so that doesn't matter much. But if you make it much bigger, you will filter out more and more high frequencies, and the only frequencies that will trigger the attack will be lower frequencies. Now here's the important bit: Lower frequencies take longer to complete a cycle and cycle less often, so it will take longer for C10 to charge. In fact, if you make the attack long enough, it could very well be that C10 discharges before a wave can cycle to charge it up again.

This is why very high resistances from the bloom control result in a big increase in volume and even distortion -- you can eventually stop compressing at all, and you're left with a buttload of gain in the dry path that's not being attenuated at all and is running through a pair of soft-clipping LEDs.