better compressor pedal??

[Fuzz Aldryn]

Hi,

there's definitely a need for a schematic: In case I wanna use a electrolytic cap for c4 and c5 which orientation should they have? Without a schem its nearly impossible to say that without too much effort!
Thx!

Helge

[merlinb]

In case I wanna use a electrolytic cap for c4 and c5 which orientation should they have? Without a schem its nearly impossible to say that without too much effort!

It's not impossible- in fact its very easy! You can see that those capacitors connect to ground (just follow the back lines...) so that end of the caps must be negative.

[merlinb]

Here is a quick sound clip. The first half is clean signal that I recorded in. The second half is the same track played back through the compressor.
http://dl.dropbox.com/u/57831278/engineersthumb.mp3

A lot of the hiss you hear is from the original recording, being amplified by the compressor, rather than coming from the compressor itself. Some of the transients did also clip my sound card, but it's not too bad.
Here's a picture of the original and compressed tracks:

[liquids]

Merlin - obviously this is a good compressor!

However, it's also nice to hear DIYers who have a bit of chops to play some music with the guitar and effects/circuit chops, too.     Nicely done.

[mr_deadmaxxx]

      

[Le québécois]

Wow, very nice sound. Now I want to build it!
I've realized that I have all the part rigth here except the 13700. Will it work with 13600?

congratulation

[merlinb]

Will it work with 13600

I haven't tried, but AFAIK it should work- they're the same OTA inside, only the darlington pair is different, but that's not used in my circuit. You could always build it with 13600 and then buy a 13700 later on.

[merlinb]

New thread started!
http://www.diystompboxes.com/smfforum/index.php?topic=97123.0

[GFR]

I designed this with a friend of mine round 1990:


ps. there's an error in the drawing, U9A + and - pins are swapped

Precision FWR from input, controlling a variable resistor in the feedback loop of an opamp (got the idea from an eti magazine project).
But, unlike the ETI project, we didn't use an OTA.

Q2 and comparator U3A are a sawtooth oscillator (around 400kHz IIRC). This sawtooth is compared to the FWR output and so we have a PWM signal proportional to the input envelope. We use this to control some cmos switches that vary the amount of signal that is fed back around the opamp.

With a good, clean power supply, there's no strange noises. I think with a good layout (we only tested on protoboard) it can be less pricky about the power supply.

If you have a large transient, during the attack time the output of a limiter is larger than the set threshold, so even in the feedback loop an OTA input can be overdriven during a short time. Also if the ratio is not infinite you can overdrive the OTA. We designed this switched limiter to try to eliminate this distortion.

The circuit can be simplified, for example the FWR is overkill - it is way too fast.

[roseblood11]

Two other interesting compressors are mictester's "Really Cheap Compressor" and "Compression Sustainer", both posted at the other forum.
This one looks very interesting as well: http://www.hexeguitar.com/diy-tadek_e
I think Fuzz Aldryn has built it, maybe he can report.

[liquids]

Two other interesting compressors are mictester's "Really Cheap Compressor" and "Compression Sustainer", both posted at the other forum.
This one looks very interesting as well: http://www.hexeguitar.com/diy-tadek_e
I think Fuzz Aldryn has built it, maybe he can report.

Yeah, I do like the look of that design.  In fact I like most of what I've seen from Hexe, schematics and pedals alike. 

I mean, that chip is more or less a 8-pin single VCA that can function as a power amp, or a 1W power amp that can be used as a VCA or simple voltage controlled volume....pretty useful, though maybe I'm easily amused   

Would love to compare noise under high squash settings.  Right now I'm using a THAT 2159/2180 type in a circuit, but I kinda wish I ordered one of those chips with my last order....gotta put it on the parts list for next time.

[merlinb]

Would love to compare noise under high squash settings.  Right now I'm using a THAT 2159/2180 type in a circuit, but I kinda wish I ordered one of those chips with my last order....gotta put it on the parts list for next time.

The TDA7052A is a noisy device, just check the data sheet! At max gain it reaches an alarming 650uV output noise... no better than an OTA, ala dynacomp.

[liquids]

Thanks for the heads up!  Obviously, I had not read the datasheet too thoroughly...  

[JohnForeman]

Two other interesting compressors are mictester's "Really Cheap Compressor" and "Compression Sustainer", both posted at the other forum.
This one looks very interesting as well: http://www.hexeguitar.com/diy-tadek_e
I think Fuzz Aldryn has built it, maybe he can report.

I'm new here so I'll ask, what is the "other forum"

[pedalgrinder]

the other forum is freeestompboxes oops take out one e you can judge the politics for yourself. On the other forum there is the  Rothwell Love Squeeze sensational unit. Sabrotone has a vero of it on his site if you want to have a look. One of the best and easiest compressors to get going you only have to read the reviews on it that say it all. Thats what i reckon anyhow.

[Xavier]

I've had / built quite a few compressors and have been a faithful CS3 user for 20 years..............and then I built the Diamond compressor as per Sabro's layout.

Compared to a "standard" Dynacomp:

- It's way less noisier
- It has WAY more output
- The compression range is (imho) far more usable, with less artifacts. It can be really subtle or squishy as hell
- It is WAY cleaner . very low background noise
- The switchable eq knob goes from pretty warm to quite bright

I guess i can say that (to me) is waaaay ahead of any other compressor I have tried (dynacomp, keeley, squeezer and the Rothwell, which I found rather disappointing and lacking any character).  I think it does both the "so-transparent-you-don't-know-it's-on" thing as good as the chicken' pickin'............I highly recommend trying it

FWIW, here's a song I made using a clon of a Demeter Compulator, which is also an optocoupler based compressor, but it's way too subtle for me (and the Diamond does it with the comp knob at 1/3 of its range !!!)

[pedalgrinder]

yeah i agree the diamond compressor is a nice one. What has been annoying me is the guitar one is there but the bass diamond compressor no one knows what has changed in it. I want the bass one not the guitar one. If i start looking at that one i will start modding it to try and get it to work better with bass wishing i had the exact recipe of the bass diamond compressor. I think thats what has put me off building one.