calling johan

[casey]

johan, please pm me, i have a question about your compressor.

thanks.

[Johan]

..I sent you a pm, but why not ask here?..others might be wondering the same things as you do...
Johan

[casey]

..I sent you a pm, but why not ask here?..others might be wondering the same things as you do...
Johan

you've got mail!

[moosapotamus]

..I sent you a pm, but why not ask here?..others might be wondering the same things as you do...
Johan

I don't know if I'm wondering the same thing as casey, but I am wondering the same thing as johan.

~ Charlie

[casey]

..I sent you a pm, but why not ask here?..others might be wondering the same things as you do...
Johan

I don't know if I'm wondering the same thing as casey, but I am wondering the same thing as johan.

~ Charlie

i am asking him about a design that i think is his...but am not for sure....

ill post my questions here in a second.

[casey]

hey johan,

the reason why i was wanting you to pm me is because i wasnt for sure if the "LA-light" compressor/limiter was your design or not, and didnt want to cause public confusion over my post....

if it is, the questions i have here i will post for everyone to see.

Questions:

1. i am presuming the la light is roughly based on the LA2A compressor.
is this so?

2. what type of power supply do i need to run it...split?

3. i am a recording engineer and was wondering what type of sources this
compressor is good for.

4. any other information you can provide would be great.
thanks!

5. what type of ratio, attack, and release are we talking about with this design.

thanks for your time...

[casey]

hey johan,

the reason why i was wanting you to pm me is because i wasnt for sure if the "LA-light" compressor/limiter was your design or not, and didnt want to cause public confusion over my post....

if it is, the questions i have here i will post for everyone to see.

Questions:

1. i am presuming the la light is roughly based on the LA2A compressor.
is this so?

2. what type of power supply do i need to run it...split?

3. i am a recording engineer and was wondering what type of sources this
compressor is good for.

4. any other information you can provide would be great.
thanks!

5. what type of ratio, attack, and release are we talking about with this design.

thanks for your time...

This is Johan's reply:


yes, it's my design.
it's based on the building blocks of the LA2a but adapted to the budget I had ( still have ) and lower voltage/partcount
after looking at the schematic for the LA2a for a long time, it really seamed like the only "magic" inside it was the input resistor/attennuator network. the sidechain is flat with no adjustments for attack/release and the gainrecovery is heavyli feedbacked woth compensation for frequencyresponce, to keep distortion low and not collor the sound. the transformers are only there for balancing and impedance reasons..so whats the fuzz?...
I run it with two 9volt batteries connected in series. there is a selfsplit in the circuit that lets the ground setle at half voltage even if the batterys have been used and dont hold the exact same voltage.
ratio according to the LA2 manual ( remember, it uses the same attenation network ) is 1:3 and 1:10 and is acctualy both Limiters, eventhou people call the LA2 "compressor
attack and release times are pretty much set by the lag in the LDR

I use it for vocals and bass. I really like how it can push vocals upfront without being "pushy"...
you can use it with a single 9volt battery, but you will have to sacrifice the indicator LED since the voiltageswing is to small to drive both the optocoupler and the indicator
the easiest way to get a good optocoupler for this one is to get a vactrol VTL5C2..but read the thread from mark hammer a coupler of days ago..
if you need ballance ins and outs, you can get transformers but I dont think you need them
the sidechain is a work in progress, but it works...

I think thats all...enjou it..

Johan

[casey]

hey johan,

the reason why i was wanting you to pm me is because i wasnt for sure if the "LA-light" compressor/limiter was your design or not, and didnt want to cause public confusion over my post....

if it is, the questions i have here i will post for everyone to see.

Questions:

1. i am presuming the la light is roughly based on the LA2A compressor.
is this so?

2. what type of power supply do i need to run it...split?

3. i am a recording engineer and was wondering what type of sources this
compressor is good for.

4. any other information you can provide would be great.
thanks!

5. what type of ratio, attack, and release are we talking about with this design.

thanks for your time...

This is Johan's reply:


yes, it's my design.
it's based on the building blocks of the LA2a but adapted to the budget I had ( still have ) and lower voltage/partcount
after looking at the schematic for the LA2a for a long time, it really seamed like the only "magic" inside it was the input resistor/attennuator network. the sidechain is flat with no adjustments for attack/release and the gainrecovery is heavyli feedbacked woth compensation for frequencyresponce, to keep distortion low and not collor the sound. the transformers are only there for balancing and impedance reasons..so whats the fuzz?...
I run it with two 9volt batteries connected in series. there is a selfsplit in the circuit that lets the ground setle at half voltage even if the batterys have been used and dont hold the exact same voltage.
ratio according to the LA2 manual ( remember, it uses the same attenation network ) is 1:3 and 1:10 and is acctualy both Limiters, eventhou people call the LA2 "compressor
attack and release times are pretty much set by the lag in the LDR

I use it for vocals and bass. I really like how it can push vocals upfront without being "pushy"...
you can use it with a single 9volt battery, but you will have to sacrifice the indicator LED since the voiltageswing is to small to drive both the optocoupler and the indicator
the easiest way to get a good optocoupler for this one is to get a vactrol VTL5C2..but read the thread from mark hammer a coupler of days ago..
if you need ballance ins and outs, you can get transformers but I dont think you need them
the sidechain is a work in progress, but it works...

I think thats all...enjou it..

Johan

and then, this was my reply back to him:


1. could you point me to a newer schematic of it. i have an old one, and dont think that my copy of it has a sidechain.

2. i want to use it for studio work. so im pretty pumped up to build it and see what comes of it. it looks to be a fun project. i am needing a decent vocal and bass limiter, so im looking forward to hearing how it will sound.

3. might even use it live

when i build it, ill email you some pictures of the completed work.

thanks for your time...

[moosapotamus]

I got it, Johan (have you figured out how to post images, yet? ).
Unless you've made some recent changes, here's the version you sent me last time this topic came up (thanks!)...
http://www.moosapotamus.com/LA-Light.GIF
If you've got any new changes you want me to post, send 'em on over.

I have a question about the terms 'compressor' and 'limiter.' Please correct me if I'm mistaken...
How is the LA-Light really a limiter? I always thought that limiting was the same as compression with an infinite ratio. Maybe once you go past something like 1:20 it starts to sound like limiting. But, it's not technically limiting until you approach 1:infinity.

Thanks
~ Charlie

[Johan]

as I've been tought,( or at least understand it..) the difference between a compressor and a limitera is this.
a compressor varies its gain around a rotationapoint, so that it will work to bring up weak signals and also decreas its gain to bring strong signals down and idealy signals just at the set treshold ( the rotationpoint ) will remain unity gain. a limiter doesnt care about weak signals, only thoose who would otherwise hit the roof, so to speak, will be affected.
look at the difference between john hollis "flatline" and the "LA-light"  they are both simple circuits with about the same parts and partcount, but the flatline varies its GAIN after the inputsignalstrength, LA-light is a set gain and the threshold sets the  "roof", but it does nothing to signals below the rotationpoint.

the last one I built was just like the one in Charlie's link only I swaped places between VR2 and the 100k in the input network to make it EXACTLY like the resistornetwork in a LA2A, the 1k/0,2uF before the rectifier is replaced with a bigger cap no and resistor and there is a cap in series with the 1k to ground to act the same way as the highpass filter in the "whatcompressor"..I havnt deside on what cap value yet so you can try different values for different applications 0,2uF=800Hz 0,47uF=340Hz 0,68uF=235Hz...and so on..

..well...I think that's it...

Johan

[Johan]

..important note that I've forgot..

set up like this with two LEDs, one in the optocopler and one "indicator", you will need to run it with two batterys or there will not be enought voltageswing to drive both LEDs. if you only want one battery you will have to sacrifice the indicatorLED. you might get away with two LEDs still if you use schotcy or Germanium diods but I havnt tested that..yet..
if you use two batteries, connect them in seriea betweenV+ and V- but not to ground, the unit will find its own ground at the exact half voltage even if the batteries hold different voltages..

Johan