compressor\limiter question

[woodro]

hi guys, is it possible to use a compressor\limiter such as the Alesis 3630 for lpfm use? I have a friend that has one he's not using and can pick it up nearly free anyone using a studio grade comp\limiter unit on their setups?

thanks in advance

woody

[woodro]

13 views, no answers or comments?

anyone?

[Sir Nigel]

Yes it's possible, in fact I know someone who used to use one. The issue I think is that it's too basic for FM usage because it doesn't take into account the preemphasis. But if you don't care about processing that, it should work. My current setup is MBL4 with a wideband compressor before the software.

[woodro]

thanks for the reply, can you tell me what preemphesis is and if its needed? i see that 75 is usually used in the us.

ty, woody

[Totallysound]

Sir Nigel,

That's the exact setup I use, and it sounds wonderful! I use a Behringer T1952 wideband compressor then into MBL4. I don't like the sound of the new Sonos with the MBL5 plugin, sounds kinda pumpy and it's more memory dependant.

[woodro]

hey guys, i've been looking at studio type compressor\limiters and see that some say they are stereo units some are not. The ones that say they are stereo compress\limiters seem to have a stereo link? what does this mean and would one of these external units need to be a stereo model. I'm not clear on where in the connection chain they fit in. I guess after a mixing board if you were using one. I plan on using a pc as much as possible so i may not even get a mixing board. That being the case would you be going from pc sound card to compress\limiter to stereo encoder to xmitter? do all components need to have the pre-emph selection. I see that the stereo encoders and xmitters do. Sorry for all the questions. guess i need a leson on audio signals

[DrSandi]

hey guys, i've been looking at studio type compressor\limiters and see that some say they are stereo units some are not. The ones that say they are stereo compress\limiters seem to have a stereo link? what does this mean and would one of these external units need to be a stereo model. I'm not clear on where in the connection chain they fit in. I guess after a mixing board if you were using one. I plan on using a pc as much as possible so i may not even get a mixing board. That being the case would you be going from pc sound card to compress\limiter to stereo encoder to xmitter? do all components need to have the pre-emph selection. I see that the stereo encoders and xmitters do. Sorry for all the questions. guess i need a leson on audio signals

Hey Wood Man...

The processors with a stereo link tie the processing together. Because of the way FM stereo is created, the two channels need to be at similar levels. Linking them together means both channels are processing as if they were a mono signal so that neither channel gets too far out of phase. Otherwise, they can sound terrible on a mono radio even though they're fine in stereo. This gear should normally go right ahead of the stereo generator or whatever is feeding the exciter (transmitter).


The pre-emphasis is used to increase the high frequencies during transmission. The receiver then reduces them back to flatness. The theory was that this would reduce the hiss in fringe reception areas. The U.S. and Canada use 75 microseconds. Most of Europe uses 50 microseconds. You can pre-emphasize in the processor or you can let most transmitters do it with a simple DIP switch or jumper setting. Remember that the radios where you are are the determining factor, since they're built with the de-emphasis used in the country they're shipped to.

All of your audio components should be flat. No pre-emphasis in anything except the last device that feeds processed audio into the transmitter. Unless your transmitter has built-in processing, then just leave it to the transmitter which should be set up to handle the pre-emphasis itself.

As for mixing, it depends on what sources you're mixing. I have a nice little Behringer mixer that I only use for mixing microphones because it has much better mike amps than my PC. But I do EVERYTHING else on the PC with Cool Edit Pro 2. It's just easier and cleaner than a console. But if you're doing live microphones and telephones, then you probably want to have a little console around for the best audio. Most sound cards have terrible mike inputs.

Good luck out there!

Dr. Sandi

[Sir Nigel]

can you tell me what preemphesis is and if its needed? i see that 75 is usually used in the us.

DrSandi answered most of it, I was just going to add that if you apply preemphasis at the transmitter, the audio can easily over-modulate. Remember you are increasing certain frequencies by over 10db! So by using something like MBL4, you add the high frequency boost, then compress it for better loudness and then you add deemphasis so if your transmitter adds preemephasis, you won't over-modulate. Does that make sense?

[woodro]

thats great info guys, thanks a million. As mentioned in my previous post i want to use my pc for as much as i can. If i end up needing an actual mixing board then i will get one at some point. Been checking out some software and seeing most everything thats really feature packed is not freeware sampling the demo (only 30 days) of Jazler2 and find it pretty cool. Wish i could get my paws on a full version. I'm affraid to go back to their website and see what it actually costs to buy..lol. Also playing with demo version of raduga v3.8 ...guess most guys dont like using winamp huh?

cheerios and thanks
Woody

[Sir Nigel]

Well, I use Winamp.