Here's Brett Robinson's simple , elegant compressor.
I haven't built it yet, but will in the next few days.
This got great reviews when it was released.
From Brett:
Possible mod: The resistor that parallels the cap at the MOSFET gate controls the "release" time. Some people like to use a pot (linear) to control release time. My personal preference is to keep things very very simple, and use a large resistor to make the release time long and slow.
R3 is right at the edge of the board. You can replace it with a pot if you wish.
Enjoy, Toney :D
(http://i2.photobucket.com/albums/y16/stm88/ozcompressorV1.png)
coming soon......ROG's Double D
I'm going to try this one in place of the squeezer side in my "bi-comprossor". Looks like a simple build for sure. Thanks again Toney. The Double D will also be built.
Yo da man ;)
"Toney" - strikes again !!
Nice, looks 95% like mine.
I never got it to perform as "smoothly" as my "Flatline" though .. !! :-(
MM.
Wow! I think I missed the schem for that one. Can anyone post a link?
Thanks!
Constantin... here you go
(http://i2.photobucket.com/albums/y16/stm88/ozschem.gif)
Haven't had time .....
Any one have a go at this yet ?
If I had a BS170, I would give it a go as soon as my bulk shipment of assorted sh*t gets here. Any suitable replacements for that particular tranny?
Yep, 2n7000
dang, ain't got one of thems either.....
should pin 7 really be connected to V+? Nothing else I've seen using a 386 connects this pin to the supply and it's marked 'reset' on the datasheet.
Rick
Good point.
I read it that way from the above schem...
Anyone chime in on this ?
very nice layout :D
MartyMart
Is this compressor subtle like the OS?
Hi.
Power to pin 6. (unlike single op-amps where it usually goes to 7)
Output from pin 5 (it usually is 6).
Virtually any MOSFET will work in this. MTP3055s are huge, but are commonly available, and only cost about $1. Note pinout.
I did partly develop a JFET version, but it was more complicated and not any better.
cheers
Excellent, thanks Brett.
Will take pin 7 out of the mix!
Quote from: SuperGeo on April 09, 2006, 09:37:38 PM
very nice layout :D
MartyMart
Is this compressor subtle like the OS?
Yeah I was wondering the same question.....
Quote from: SuperGeo on April 09, 2006, 09:37:38 PM
very nice layout :D
MartyMart
Is this compressor subtle like the OS?
No, but then i don't think my OS is subtle at all !!
I liked it, but was just struggling with the "attack/decay" and the pumping.
I have it set up with an extra pot ( see original thread ) and have some control
but was never quite satisfied with it .... sorry !!
"Flatline compressor" or Craig Andertons compressor are great, the Flatline is on
my pedalboard at the moment.
They are a little more "complex" as builds though ... CA comp is a +9/-9 volt circuit !
MM.
^Has the issue with this layout been fixed? I think I'm going to build this if it has.
Yep, fixed same day.
Some love it some do not.
Remember, one variable can be the 386 chip used.
There are several differing types and may/may not yield different results.
Haven't tried, but this occurred to me after the varying reports.
Hi.
I initially used the Aussie for short, fast, loud rock, so I didn't notice any "breathing" or ups and downs. But I can see that it's a problem.
I've been thinking about the long release time. In the Dyna compressor, which I really like for its sound, the resistance paralleling the "holding" 10uF capacitor ranges is about 10kohms (when the pull-down transistors are "on" enough to turn Q5 off and start compressing). So the combined resistand and capacitance and release time is WAY shorter than in the original Aussie compressor.
So maybe a better value for the 1M resistor is around 22k ?? 22k and 4.7uF gives a time constant, RC, of 0.1 seconds. I *guess* that 0.1 seconds would be short enough to give a quick(ish) response to the envelope of a picked note, yet slow enough not to follow even the lowest frequencies (ie it is equal to 10 Hz). Hmmm... probably too fast for even the fastest vibrato.
I'm up to my ears in a McTube at the moment (a really excellent project), so would someone else like to try 22k (and maybe 47k) in place of that whopping great 1M resistor?
cheers
Right.
So basically, when building remove R3 ...it's right on the edge of the board for this purpose....with a 50 or 100k pot for adjustable release time...
If anyone does this , please report how it goes.
Anyone built this yet? Seems like the 386 would sound sort of 'lo-fi' and fuzzy instead of bright and clear?
I'm guessing a tl072 could be subbed pretty easily (not pin for pin though), which may make it a little clearer.
bw
"Lo-fi and fuzzy" is exactly what I got after breadboarding, Brian. I'm going to try a few different 386's as stated above, and a bit more tweaking of component values and see if there are any different results. Back to the drawing board!
George
Quote from: G.Neyrey on April 21, 2006, 09:22:00 AM
"Lo-fi and fuzzy" is exactly what I got after breadboarding, Brian. I'm going to try a few different 386's as stated above, and a bit more tweaking of component values and see if there are any different results. Back to the drawing board!
George
I said this in the original thread...if it is going to work by altering the volume/dynamics going in to the opamp, the way most compressors work. it needs a series resistor between input and the fet/mosfet. As is, it works by loading down the previous stage ( guitar or fx's or whatever) wich will give VERY warying results depending on what you feed it with...I would just install a 20-80k resistor
johan
Which makes sense...given the varying reports.
I haven't got around to building this myself yet.
I will tomorrow , if there's time and I'll try a few of these ideas...
I"d really like to keep the ball in the air with this one... lets keep it going.
All suggestions welcome, lets finish it.
I'm not going to get a chance to build today, but I've added to the layout.
When we get the right pot resistance paralleling C3, the 4.7u, there will probably be a cut off point where the pot does nothing so easiest thing is to add a resistor as a min point.
It's R3 on this new layout...I've left the values out for now.
If someone wants to do the test tweaking, just connect up a 50 lin pot where R3 was on the top of the page layout.
Find the sweet range of travel, high and the low cut off, and then I will add the values to the layout.
Next task is to add a series resister as Johan suggested. A pot would be the quickest way to find the value for this 100kb should do it.
It needs to go between the cap and the drain of the trannie, so you'll need to move C1 for now to achieve this. When we find the most suitable value, I'll rejig the layout.
C'mon...who wants to give it a shot??
(http://i2.photobucket.com/albums/y16/stm88/Copyofozcompressorv5.png)
I will, I'm ordering parts right now :)
My posts have been poned or whatever that stupid expression is...
Anyway, here's a re-do of the layout for tweaking. I've added a trim pot for ear-tweaking the threshold most suitable for the cap to mosfet resistance.
Try a 50k trim- use a pot if that's easier.
My layout's been chop-suey cut up so much .... might re-do the whole thing once we have final values
(http://i2.photobucket.com/albums/y16/stm88/Ozcompressorv8.png)
"As is, it works by loading down the previous stage ( guitar or fx's or whatever) wich will give VERY warying results depending on what you feed it with...I would just install a 20-80k resistor
johan"
Thanks, Johan. I suppose I missed that the first time around! I'll give it a shot the next time I'm on the bench.
George
Quote from: Toney on April 24, 2006, 04:32:03 PM
My posts have been poned or whatever that stupid expression is...
Its "pwned."
Yes, one of the few words without a vowel. Weird eh?
Parts in mail...
So what exactly are your additions of C5, C6, and D2 accomplishing? I haven't seen anywhere in this thread where you explained why they were added. I ordered the parts to build this and am waiting on them, but I haven't ordered those additions, because I ordered based on a different thread.
Thanks,
CJD
Almost forgot - Where do the additions sit on the schematic? I am doing my own layout on perfboard for the experience and don't want to just copy a vero layout.
Look where they are. Look where 9v and ground are...
They are power filtering and reverse polarity protection.
So they connect in parallel from 9V to Ground? Sorry. I was just having trouble tracing that Vero. The other side of it actually, so I didn't bother looking at the right side. I'll work that out too, as it would be valuable.
Thanks
I'm off to the soldering iron, will report shortly :)
Quote from: Toney on April 24, 2006, 04:32:03 PM
My posts have been poned or whatever that stupid expression is...
Anyway, here's a re-do of the layout for tweaking. I've added a trim pot for ear-tweaking the threshold most suitable for the cap to mosfet resistance.
Try a 50k trim- use a pot if that's easier.
My layout's been chop-suey cut up so much .... might re-do the whole thing once we have final values
(http://i2.photobucket.com/albums/y16/stm88/Ozcompressorv7.png)
What's that resistor to the right of the trimpot?
Hi Rockgardenlove,
Sorry about that hasty redraw, I've been meaning to clean it up.
That's R1 - 1M
Ok, cool. Thats what I thought, just wanted to check. I assume the green cap to the right of the 1m resistor is .1 uF...is that right?
Yep, that's it.