Really Cheap Compressor

Mbas974 · Post by **Mbas974** » 16 Feb 2014, 21:01

Hi, is there a way to put into this circuit attack and sustain control ?
I suspect 10K prior Pin6 and 1K post the leds but just guessing....

hornilla · Post by **hornilla** » 20 Feb 2014, 00:28

I'm thinking about building the version for bass. As my bass uses active pickups: Any idea if the compressor is going to work fine with these?
Thank you!

zedsnotdead · Post by **zedsnotdead** » 01 Mar 2014, 01:25

Hi guys,

just built it, so I took a couple of shots, here it goes:

Picture 1: see how i try to stop any external light source from hitting the ldr? just made a small box using some cardboard, and glue it to the pcb.

Picture 2: this is how far I got the LDR from the leds. I guess this is about the right space, the compressor really kicks!

Picture 3: overall gutshot

Picture 4: I did it on a 1590G enclosure. here's a pic comparing sizes with the 1590B (ep booster).

Now, I read in this topic some doubts about the leds didn't light up when testing the circuit. So I recorded this small video and show you how it should lit.
I am on my living room, only the TV is on. Also, the bright blue led is on. With the compress knob fully CW (100%), when I hit the tip of the cable with my finger, feeding the circuit with a signal (noise), this is what you should expect:

Hope this video helps.

smackoj · Post by **smackoj** » 06 May 2014, 10:28

ola amigos; I just finished my first RCC aka really cheap comp., and I have one sorta problem. It's working (passing signal) but it's padding the signal something like -10 or more db! I put a clean booster in front of it and it sounds great that way. Anyone have a guess on what I might need to do or undo to get a full volume signal through it? I followed the schemo closely other than a few values on caps which were ones I didn't have the exact value.

gracias hombres. smacko jack

Willybomb · Post by **Willybomb** » 01 Jun 2014, 08:35

Just a followup - I've built the vero layout on page 8 with the bass values, and finally put it in a multi. There's an interesting side effect, and I was wondering if anyone could tell me why...

The bass is plugged in, and with all the effects off, there's a bit of noise - it's not as quiet as I (anyone) would like. But that's just the amp. Anyway, when I kick on the compressor, still not playing yet, probably 90% of that noise is gone, it's actually REALLY quiet. Play bass, noise stays gone, just the compressor doing it's thing. What's in the circuit that would do that?

RasIbo · Post by **RasIbo** » 24 Jun 2014, 20:00

To introduce myself;
Hailing from Amsterdam, the Netherlands, i'm a Reggae producer \ musician
born in 1965, now working mostly in and on my studio at home.

I took a swing at building the RCC.
Here's my design!

: Was cheap, except for the pot's and housing

Works fine, i use it as an insert on my horn tracks, wicked!

Greetings,
Ibo Jacob
http://www.ibojacob.com

Neur0 · Post by **Neur0** » 17 Aug 2014, 15:48

Hello everybody,
I too, am new here in tems of posting. Been nosing around for a while though

I'm Dutch guy, 44th winter coming up soon.

My question is about the LDR for the RCC.
I ordered two of them and they are supposedly 10k L - 1M Dark. When I put my DMM on them they both read less than 2k light and 40M+ dark.
Does this mean I've been sent the wrong ones? They don't have any printing on them so I can't really tell which ones they actually are since they are the first ones I've ever seen IRL.

Thank you for this amazing community by the way.
It's great fun to read through all this knowledge written by kind people to feed my new found addiction

Neur0 · Post by **Neur0** » 19 Aug 2014, 09:35

Awesome little device you made there mictester, thank you so much! This is my 4th build, but the first one to work correctly straight away. Probably has to do with me getting the hang of soldering techniques and avoiding it's pitfalls.
Well, it seems to work pretty well with the 3mm green LED's and the LDR I mentioned above.
I made one for myself to test (guitar) but the initial idea was to make one for my wife, who plays the bass guitar.
There is an issue I am struggling with.
The compressor seems to kick in pretty quickly as I "reduce" sustain (Yeah I'm working with the reversed functioning potentiometer since I find it hard to translate the fixed version to vero).
What would be the best way to make the led response kick in more gradual? I mean, for myself I find anything past 12 o'clock on the sustain knob obsolete, so is there any way to spread that out over the entire sweep?

Thanks.
Remy

induction · Post by **induction** » 19 Aug 2014, 14:30

Neur0 wrote: The compressor seems to kick in pretty quickly as I "reduce" sustain (Yeah I'm working with the reversed functioning potentiometer since I find it hard to translate the fixed version to vero).
What would be the best way to make the led response kick in more gradual? I mean, for myself I find anything past 12 o'clock on the sustain knob obsolete, so is there any way to spread that out over the entire sweep?

Yes, there is. Don't reverse the sustain pot.

The circuit calls for a log sustain pot, which is designed to change very gradually at the low end of the pot and bunch up the variation at the high end of the pot. By reversing it, you've reversed the sweep, so it changes very quickly at the 'low' end and almost not at all at the 'high' end. I would swap the wiper connection so that sustain increases clockwise and the sweep is correct. If you prefer a reversed sustain pot, you will have to find a reverse-log pot to use instead. You could try a linear pot, which will give the same sweep in either direction. The sweep will be improved, but it will steel feel a bit bunched up at the low end of the pot.

Neur0 · Post by **Neur0** » 19 Aug 2014, 14:40

That makes sense. It's so simple but my lack of experience made me overlook that aspect of behaviour of the pot.
Thank you, induction.

Silver Blues · Post by **Silver Blues** » 19 Aug 2014, 21:38

Last few posts prompted me to fix mine, I've had the pot backwards since I built it but never cared to fix it until now. As it turns out, if you want more compression as you turn clockwise, you need to connect the pot as 1 and 2&3, not 1&2 and 3.

Awaking · Post by **Awaking** » 01 Sep 2014, 06:10

jimmybjj wrote:UNverified layout. Eagle doesn't show any errors. If anyone see's one let me know.

Layout here

I built it too.

Awaking · Post by **Awaking** » 01 Sep 2014, 09:37

Now I have a problem with clipping of input signal.
I've replaced 220K resistor with 390K, but it not helped.
Here is the sample with 390K resistor
First part is clean signal.

Groovenut · Post by **Groovenut** » 11 Sep 2014, 19:45

mictester wrote:I posted a simple approach to introducing passive pre- and de-emphasis (earlier on in this thread) - this can very slightly reduce hiss at high gain, but I've generally found it not to be necessary.

The approach Mictester is referencing in this quote is actually in another thread

https://www.freestompboxes.org/viewtopic ... se#p188345

cozybuilder · Post by **cozybuilder** » 15 Oct 2014, 22:11

I'm finished, it sounds good. Thank you Mictester for another fun project.

rocklander · Post by **rocklander** » 15 Oct 2014, 23:06

that is a superb piece of engineering!

Greenmachine · Post by **Greenmachine** » 16 Oct 2014, 03:38

Hats off buddy. Quite a build you got there.

phatt · Post by **phatt** » 03 Apr 2015, 11:24

OK old post but I have built this Compressor and it works well except for hard rectification on full tilt.

I've just re-read all 15 pages and noted a few have mentioned this issue which seems to be related to LDR's with very high dark resistance.

Ok so with another breadboard setup and many hours of highly qualified guesstamation (poking parts into holes)

,I've found a solution which maybe helpful.

(See schematic)

Seems anything from 1nF~ 10nF will do the trick.

My Circuit notes.
Build as per MT's original circuit with one extra Red led for panel indicator and a couple of minor tweaks. i.e. 500R to ground from Leds. (was 1k)
I'm using LM833. > fully reg 9VDC supply. > 5mm Green Leds for LDR in black shrink tube, my LDR measures ~20Meg Dark.

Hope it helps, Phil.

marcao_cfh · Post by **marcao_cfh** » 26 Oct 2015, 21:06

Here's mine:

Gobi · Post by **Gobi** » 11 Mar 2016, 23:53

First let me say thanks for this realy nice build!
I'm brand new to the electronic stuff and realy struggeling.... avter a few mistakes i finaly get it running.
I'm trying to understand and learn something, so I started to modyfi - direction was to get more sutain. This is what I finaly get till now:

I started with more amplfication in OPAmp1 , and tryed to set the regulation on the LED side... I could get even more sustain, but then I was not able to reduce it anymore... so i got this compromise....
After hours of trying and listening, im unshure- could somenone tell me, am i going in the right direction, or is it a fail anyway.

Sorry for my bad english, I'm from germany

Really Cheap Compressor [documentation]