compressor - stripped down

[vdm]

i need to make a compressor for a cd input. The pupose is to compress the whole song, much like is done on the radio or in cassette tape recordings, where the soft sections are amplified to match the loud sections.

i was looking at the led/ldr comp in the japanese effect book, and i was trying to think how can i make it as simple as possible. the frequency response isnt too much of a worry. it's for a uni assignment that begins tomorrow.

its a beginners electronics course, mainly just about learning how opamps and the such work. so if anyone has any other suggestions (they must be very simple - the compressor is almost too complex) they are most welcome.

thanks for any input

trent

[petemoore]

I think the Orange Squeezer Compressor meets you're needs.
 It is a comparitively very simple compressor, uses an Op Amp,  Does the Soft, mild Compression job very well.
 The schematic and related items are at TonePad.
 The Ross is 'squashier', [harder compression], and more complicated, info at Tonepad.

[Mark Hammer]

A compressor is not a compressor is not a compressor.

What makes for a "good" compressor for one type of instrument is not necessarily a good one for another, largely because  the way the unit "rides the waves" determines how well it captures and preserves the character of that instrument.  Naturally, you would expect different sorts of requirements for a unit intended to keep a snare under control to be different than those for a vocally-oriented unit; partly because of voice vs drum envelope characteristics, partly because of dynamic range, partly because of bandwidth/pitch factors, and partly because of the variations in inter-impulse gaps (the space between each "demand" on the unit to rein in level).

Of course, if you think there are differences between what makes a useful compressor for voice and drum, there are most assuredly differences between what makes a useful compressor for guitar and what works for an entire multi-source track, where the peaks produced by one source have to be controlled without having an impact on whatever the other sources are doing at the moment.  Remember, there is no guarantee that when the bass player pops a note with their thumb, that it will occur the precise instant the drummer hits the snare.

The Orange Squeezer and Ross/Dynacomp compressors are very nice units and quite suitable for guitar.  I have my serious doubts as to whether they are suitable for "massaging" the sources you wish.  First, neither are intended to deal with line levels.  Second, both have sidechains (the envelope follower portion) that are intended to respond well to the sorts of attack and decay characteristic of guitar.  Third, I think they are designed in anticiâtion of a different output impedance feeding them.

You CAN make each of these "behave a little better", but the stock unts will not likely do what you want.  It won't involve a total redesign, but you'll have to be tolerant of changes.

[moosapotamus]

Hey trent... I don't have the japanese effect book schemes handy right now, but another very simple compressor that may be much better suited to overall mix compression from a CD might be the LA-Light.

Check out Johan's latest revision in this previous thread...
http://www.diystompboxes.com/sboxforum/viewtopic.php?t=20426&highlight=lalight

... and do a search if you're interested in more info.

~ Charlie

[StephenGiles]

If it pleases the court, might I suggest the What Compressor here:
http://dt.prohosting.com/hacks/what.html
absolutely brilliant, forget the 33178, I used TLO72. A very transparent compressor and easy to build.

[moosapotamus]

Stephen - you've built a What Comp? What layout did you use? This one...
http://1176neve.tripod.com/1176/id5.html

Thanks
~ Charlie

[StephenGiles]

Stripboard as usual!

[moosapotamus]

:shock: Wow! I'd prolly go crosseyed!

~ Charlie