freestompboxes.org

Just want to say thanks too, I just built it, took a couple hours, and it sounds really great! Thanks for all the work.

uki wrote:Hey thanks for this !!

I just build one and it is really good ! "Is it on?", but miss it when it's off! That is exactly how it is !

Which schematic of the posts did you apply?

man, i've built a bunch of these for friends, decided to build one for me.

used all metal film resistors, poly or tant caps where applicable and made it on a 12x11 piece of vero. it works, and i can see the leds flash a little (or could before i sealed 'em up... again... with the second take on the homebrew vactrol.

it squishes, and it compresses... but i can't get even close to unity gain out of it with the volume pegged. the last one i built would rip your head off!

i've replaced the leds and ldr a couple times... last time pair of water clear yellow 5mm's and the ldr reads 1.3m in darkness.

but the tone is kinda muted a little, and the volume needs to come up.

i just read all 19 pages, and tried a bunch of things, but i'm stumped.

any ideas? it sounds great, but its not loud enough.

beginning to think the oa is bad. brand new 5532. its weird. this thing is normally pretty ferocious!!

thanks my friends

pinkjimiphoton wrote:man, i've built a bunch of these for friends, decided to build one for me.

used all metal film resistors, poly or tant caps where applicable and made it on a 12x11 piece of vero. it works, and i can see the leds flash a little (or could before i sealed 'em up... again... with the second take on the homebrew vactrol.

it squishes, and it compresses... but i can't get even close to unity gain out of it with the volume pegged. the last one i built would rip your head off!

i've replaced the leds and ldr a couple times... last time pair of water clear yellow 5mm's and the ldr reads 1.3m in darkness.

but the tone is kinda muted a little, and the volume needs to come up.

i just read all 19 pages, and tried a bunch of things, but i'm stumped.

any ideas? it sounds great, but its not loud enough.

beginning to think the oa is bad. brand new 5532. its weird. this thing is normally pretty ferocious!!

thanks my friends

Sounds to me like your leds might not be turning off (or turning on too easily) and causing the ldr to stay at a low resistance. Try raising the 1k resistance between the leds and ground to lower the current through them and make the leds turn on at a higher threshold.

nahhh, bro, it was my own stupidity. on the vero i worked up, i had the cathode side of the 10u cap connecting to the input side of the 15n cap instead of ground where it should have been. made for some amusing experiments. you can get some crazy oscillations outta this thing.

so when all was said and done, probably took longer to open the box than to fix it.

i did end up adding a treble peaker on the 220k resistor, to my ear 220p seemed perfect. i may add the series resistance, and the 10n cap bypassing the wiper to ground to de-emphasize the treble, but it doesn't seem necessary.

also went with a 100k output pot, which seems to work fine so too lazy to change it back.

my fav app for this is after fuzzes and a ns2... can really add a nice sheen, and a fuzzface into it can be unfathomably versatile.

i'll bring it to my thursday nite show this week and piss off my rhythm guy with the expensive ass joe meek or whatever compressor... this thing blows it away

it DOES get a little overdrivey sometimes... but i kinda like that. and with the 100k output pot, you can drive your amp into a nice sweet singing sustain without a lotta noise.

said it before, will say it again... hats off to you chris for this really groovy little circuit!! rock on bro... RESPECT

pinkjimiphoton wrote:
it DOES get a little overdrivey sometimes... but i kinda like that. and with the 100k output pot, you can drive your amp into a nice sweet singing sustain without a lotta noise.

Totally AGREE,, that is what makes it so darn brilliant,,IME this is as close to a classic valve amp Triode Rattle with Compression as you can get AND close to noise free.
A lot of compressor circuits add a lot of noise and I've used all of the boss stuff as well as many others and built a few but they all sound dead by comparison.
The Boss CS3 is low noise but still no Triode rattle,, way too clean to sound convincing for guitar.
I don't even bother using a Valve head anymore just using an old Laney keyboard amp.

pinkjimiphoton wrote: said it before, will say it again... hats off to you chris for this really groovy little circuit!! rock on bro... RESPECT

I second that line,, such a simple circuit to build and just brilliant.

it is truly the only compressor that has ever made it to my live board.

its mindless and perfect. near endless sustain, and the ability to play clean the kinda shit you'd normally require at least some overdrive to do.

i bet with the addition of some clipping diodes it would make one hell of a little od

".... with the addition of some clipping diodes it would make one hell of a little od ...."

Mr. Photon, I think you subconsciously crave a Rockman Sustainor.

pinkjimiphoton wrote: I bet with the addition of some clipping diodes it would make one hell of a little od

Hi Jimi. I've experimented with the circuit a lot. I built a version using a quad op-amp (TL074) with the compressor (the first two op-amps) driving into a diode clipping stage (two switchable options - to ground or 'round the op-amp feedback path), then into an active Baxandall tone control. This makes for a very interesting pedal. If you set the compressor section for medium squish, then drive the clipper stage into moderate clipping, you can get endless sustain, and the kind of heavily compressed, distorted sound that the Big Muff Pi does when set to highest gain with humbuckers driving it.... However, it's more controllable. You don't get random bursts of feedback when you stop playing. It allows beautifully liquid solos....

I used 4066 gates for bypass, and allowed the circuit to work as YATS, a clean compressor, or both together. I came up with a neat little PCB, with a 40106 for the push-button bistables, two 4066s for routing (and muting to prevent breakthrough) and a TL074 for the actual business end of the thing. I'll put the PCB up here shortly - when I have some time to convert my scribbles to something coherent!

pinkjimiphoton wrote:it is truly the only compressor that has ever made it to my live board.

its mindless and perfect. near endless sustain, and the ability to play clean the kinda shit you'd normally require at least some overdrive to do.

i bet with the addition of some clipping diodes it would make one hell of a little od

Hi bro Jimi

there are different schematics on the topic,
which of it did you use?

mictester wrote:
...
I used 4066 gates for bypass, and allowed the circuit to work as YATS, a clean compressor, or both together. I came up with a neat little PCB, with a 40106 for the push-button bistables, two 4066s for routing (and muting to prevent breakthrough) and a TL074 for the actual business end of the thing. I'll put the PCB up here shortly - when I have some time to convert my scribbles to something coherent!
...

You're actually much much worse than SR&D.


Edit: with the original simple dual-opamp circuit; the second opamp that drives LEDs could be very easily converted to a band-pass filter (150Hz to 2.5kHz) which could be further used to drive a diode clipper a-la Dist+, Rat etc. for the "smooth" drive.

This way, you could (from the existing schematic) derive two outputs: one "clean sustainer" and the second "smooth dirty" output, selectable with a stomp-switch.

Who's gonna be the first to put up the working prototype? (Me not).

hey chris, i'd love to see what ya did bro!! sounds pretty awesome!
i built a big muff pi with ridiculously low gain q's and it sounds kinda like that. can be really useful!
thanks once agaon brother!!

manfred, i built the totally stock circuit other than using a 5532 for the OA and a 100k linear for the volume. i basically took the vero layout on tagboard and ...hahahah.. "compressed it" just enough to fit in a 1590a.

Hey Doc Photon; when you're in the mood, you can try a simple little mod that will require moving a single resistor around the LEDs and soldering one additional pot to your existing R.C.comp to get the "dirt" output, similar to what's described here:

words: http://www.moosapotamus.net/fatNpretty.html
schem: http://www.moosapotamus.net/images/Fat-n-PrettySCH.gif

Edit: It would be also advisable to add a 330-560pF cap across the 2nd opamp NFB for the "dirt" mod to reduce the pass band down to cca 4.5 or 2.5kHz.

thanks bool!

but no room for another pot, i got this crammed in a 1590a with two 16mm alphas, an led and the obligatory two jacks and 3pdt. there's no where to stash anything else.

on THIS one.

maybe on the next. i've been thinking about using this as the ass end to another circuit for a while. for all intents, thats what bixonic did with the expandora... a rat into a compressor. love it.

samhay wrote:Hi,
I have built one with a LED compression monitor nevertheless. There was some mention of this earlier in the thread, but I don't think anyone posted a schematic. Here is what I used. I am not particularly savvy with MOSFETs, so there may well be better ways to do this.
In keeping with the ethos of this circuit I kept it as minimal as possible - a MOSFET, LED, resistor (tune to taste) and optional zener (to keep the MOSFET safe). It is gated by the threshold voltage of the MOSFET, but works pretty well across most of the sustain pot's range. It is a switch rather than amplifier circuit, so you do not get much of a variation in brightness - the LED is mostly either on or off - but it gives you an idea of what's going on anyway.
If you want to retrofit existing circuits, you could build it on a daughter board by adding a capacitor (e.g. 1uF) before the gate and connecting it to the sustain pot's output.
[ Image ]

I know it was a long time ago, but do you happen to have the layout for an indicator led? Im about to build a new comp, and i have a hole already drilled in the enclosure that begs for an indicator led!

If anyone's willing to help...

Nevermind, I found a schematics for a Flatline/Madbean Afterlife indicator Led, that works perfectly well with the Really Cheap Compressor!

http://www.madbeanpedals.com/forum/inde ... 4856;image

Putting a led in parallel with the green leds isn't a good idea, it affects the sound a lot (distortion) and the dynamic too. This little circuit will give you perfect indication of when the compression works!

Boba7 wrote:Nevermind, I found a schematics for a Flatline/Madbean Afterlife indicator Led, that works perfectly well with the Really Cheap Compressor!

http://www.madbeanpedals.com/forum/inde ... 4856;image

Putting a led in parallel with the green leds isn't a good idea, it affects the sound a lot (distortion) and the dynamic too. This little circuit will give you perfect indication of when the compression works!

Where did you tie the circuit into for the Really Cheap Compressor?

karter2000 wrote:

Boba7 wrote:Nevermind, I found a schematics for a Flatline/Madbean Afterlife indicator Led, that works perfectly well with the Really Cheap Compressor!

http://www.madbeanpedals.com/forum/inde ... 4856;image

Putting a led in parallel with the green leds isn't a good idea, it affects the sound a lot (distortion) and the dynamic too. This little circuit will give you perfect indication of when the compression works!

Where did you tie the circuit into for the Really Cheap Compressor?

Same place as in the schematics: pin 7 of the opamp (or pin 2&3 of the sustain pot, same thing)

guys,
if you, like i , had a problem with distortion on the compressed signal and rolled your own vactrol like i did... i actually put both leds on one side and the ldr right against 'em and shrink wrapped it... originally. there was always an edge of distortion to it i couldn't get rid of.
last nite i remembered in my fuzzy out hippy brain having a similar problem with the wobbletron/magnavibe
so i cut open the shrink wrap and dragged one of the led's out of the vactrol i'd made. bit of an improvement.
as i started dragging out the other one i noticed the distortion was going away as i backed the led from the ldr... i'd used golden/orange leds on this build for some reason, clear 5mm ones. at about 1/4 of an inch or so separation, i lost the distortion and gained all the compression i'd never realized was on tap, as well as several db more headroom. i used to have to dime the volume just about to get unity gain, now unity is about 9:00-ish.
getting some great squish and got the whole thing stuffed in a 1590a. works great.
so if you're getting distortion, try increasing the distance between led and ldr. you don't need to wrap them once its in the box... but make sure leakage from any indicator lamps is blocked off, cuz that WILL affect it.

I have a small hobby PCB router so I've decided to create a PCB so that no wiring is requried for this compressor and that it can fit inside 1590B case. To do this I needed first to create schematics abd board layout in Eagle. Here is the attached screenshots from Eagle with schematics and board layout. I will attach original Eagle files if people would like to use it themselves.



Once I have done this I exported gerber and excellon files from Eagle and imported them into Flatcam to create gcode for my PCB router. Here is a screenshot from Flatcam. I used FlatCam to create gcode to cut PCB.


I used bCNC app to run my hobby PCB router that is using arduino GRBL implementation to control motors and spindle. Here is the PCB after milling.


Now I need to Tin it and solder components. Will post the final result.

Finally the question. I need to understand how to properly assemble LDR and Leds. Many of you are putting them together and shrink wrapped them to protect from external light. Some of you are stating that if they are too close to each other can introduce distortion. Therefore I have decided to design enclosure for LDR and leds which can be easily 3d printed and will ensure repeatable successful assemble of them. I would like to use 3mm green leds because they are small so that enclosure is small as well. So the question is - is it possible to use 3mm green leds and if yes how far from LDR I should put them. Thanks !