La light compressor without fets

[Prive]

I've lost the schem, can anybody point me some link or send me an email for the La-light without minibooster stage please?

Thanks in advance, saludos, Marcelo.

[moosapotamus]

I have Johan's original scheme posted on this page...
http://www.moosapotamus.com/Fat-n-Pretty/fatNpretty.htm

If you've done a search, you've realized that the link I posted to his more recent version is broken. I lost a bunch of stuff when my host provider went belly-up. I think I might have it on another computer, tho. I'll take a look.

Meantime, if Johan sees this, he might be able to send it to me, again, faster than I can find it.

~ Charlie

[Johan]

I see it..  

Ive updatetd it again
I now use three parts of a quad opamp, leavivg the forth for a input bufferstage if anyone wants one. I use one stage for stable biasing without a big cap ( similar to R.G's biastrick ) alowing it to take any voltage that the opamp can handle, 9volt or up to 40volts with some opamps.."Mmm headroom..".. You can off course do it the regular way with just two resistors and a cap, and get away with any dual opamp.
but the most important change is using a rectifier bridg in the led drive. the reason for this was that I had trouble with some LDR/LED combos and did get a little bit of distortion. with the rect.bridge I can pretty much use whatever I get my hands on...

if you still have your old emailsddres, its on its way...

Johan

[moosapotamus]

Here it is...
http://www.moosapotamus.com/LA-Light.GIF

Thanks (again :wink: ), Johan.

~ Charlie

[Prive]

Thanks a lot!!!!!

I find some little LDR's with 2M light / 2K dark, so i want to build it and give it a try with my ham-radio station obviously to process the mic  :wink:

I'll post some results.

Thanks Charlie and Johan for sharing

Saludos, Marcelo.

[seanm]

I see it..  

Ive updatetd it again
I now use three parts of a quad opamp, leavivg the forth for a input bufferstage if anyone wants one. I use one stage for stable biasing without a big cap ( similar to R.G's biastrick ) alowing it to take any voltage that the opamp can handle, 9volt or up to 40volts with some opamps.."Mmm headroom..".. You can off course do it the regular way with just two resistors and a cap, and get away with any dual opamp.
but the most important change is using a rectifier bridg in the led drive. the reason for this was that I had trouble with some LDR/LED combos and did get a little bit of distortion. with the rect.bridge I can pretty much use whatever I get my hands on...

A couple of questions... Any recommended diodes in the rectifier? Si? Ge?

Why two leds? If I use a CLM6000, should I add a second led or diode?

[Johan]

hello Sean

the reason for the second LED is only to have a visual aid, to see when you pass the thresshold and when the unit is starting to work. if you dont want or need it, you can just remove it. the diods can be any diods you might have in your parts bin.
you will need to use it with two 9volt batteries or else there will not be enough voltageswing availible to drive both LEDs. you might get away with a single battery if you use schottky or Ge diods, but I havnt tried that yet..
the sidechain is an ever evolving work in process and i make little changes everytime i builld one ( those who get to try mine usualy insist on me making one for them too..) and the last one had a simple, sweep-able lowpass to compensate for different voises or instruments.
I still dont have any where to put it on the net, but I could mail it to those who are interested, just send a pm..

Johan

[puretube]

...

I find some little LDR's with 2M light / 2K dark...

I`d love to find those kind!  :wink:

[radio]

Em

Wouldn't be easier to build it around a

THATS4301?

At least as far I understood the datasheet?

Greetings Jimini

[Johan]

Em

Wouldn't be easier to build it around a

THATS4301?

At least as far I understood the datasheet?

Greetings Jimini

..well...just building a compressor, with flat responce, good specs.  that "does the jobb" isnt very hard..there are many chips out there that does it all with a minimum of supporting parts, but thats not the point..the whole idea behind the LA-light was that I wanted a "Sound" for my vocals that I just couldnt get with any of the compressors I had availible..and there was many, DBX's, Symetrix's, Drawmer's and so on..so i focused on the one "compressor" I know was used on many of my favorite vocal recordings..the teletronix LA2A, and tried to make a simplified "workalike"..the result is the LA-light...I am obviously biased about the result, but from what those who tried it reports, it appears to do a good jobb...

Johan

[radio]

Johan

I didn't want to offend anybody I just had a feeling

your design could suit guitarrist needs better

than chips that achieve a 20to20kHz response!:oops:

So my question should have been:

" What does a guitar compressor need to have versus

any  compressor  to  suite  that  specific  job?"

Greetings JMErnzer

[Johan]

dont worry Radio..
..I acctually buillt it for siting in the insertjack of my mixer when recording vocals, so its not really intended as a stompbox, wich is why I never pushed very hard for it here.
I think for stompbox use, higher gain in the sidechain would be a good idea and also an inputbuffer, becouse the input impedance is not only very low, it is also dynamic, going as low as 30k. if you use a quad op-amp such as tl074, you will allready have a spare section you can use.
all the "classic" compressors like the SSL, LA2, 1176 all have a certain "sound" ( wich is why they are classics..)most "modern" and sheap compressors in comparison, just sound flat and often boring ( I.M.O ). my guess is that if you look at the "boring" compressors, they will display a flat frequency response, at all setings, no matter what you do. and the "classics" will behave different at different gain reductions ( G.R). so the most interesting thing to do would be something like looking at frequencyresponce at different points like 10db G.R or 20db G.R and so on. at the moment,  I'm trying to track down equipment to have a closer look at the electroluminecens-panels that are used in the LA2, so I can see how the brightness is affected by the frequency. will it be as bright at 100Hz as it will at 2kHz given the same RMS voltage? ..if not, what would the curve look like?..and in the end..how can I emulate that curve in the simplest way, to use for my own projects..

Johan

[radio]

Thanks Johan

The only guitar project close to a compressor I build

was a sustain unit based on  error-amp with Fet

giving you a "fixed sustain" that had an adjustable

attack/decay. Here is the schematic:

http://webplaza.pt.lu/jmernzer/iceland/sichipauproj81b.gif

Greetimgs
JMErnzer

[sean k]

Hey Johan,I ain't too clever at this stuff,still learning,but I'm thinking its going to be brighter at lower frequencies simply because bass pushes current so an additional side chain that created a current envelope,as opposed to a voltage envelope,and this was run alongside the proprietary voltage envelope and somewhere along the line a bit of resonance was thrown in...but its always easier to be theoretical when you haven't got the knowledge to put it into action.
But I definitely like the fat'n'pretty and will be going there sooon as!Good one Moosapotamus!