Setting the Gain Structure

cadillacfella

I'm attempting to set up my system's gain structure. I have two JBL PRX 612m, and two JBL PRX 718s along with a dbx DriveRack PA+. I have been following a combination of set up instructions from the DriveRack manual as well as the advice from the Get Started forum. I was able to adjust the 612's without any issue, but when it comes to the subs and with all other equipment pinked just below clipping, I can turn the gain on the subs all the way up with no clipping. Do I have something set wrong? Are they not getting full signal? I didn't think they would do that. Any thoughts?

Gadget

Not sure, that's a new product... but it clearly states on the site that:
"Overload: Red LED indicates input overload condition"
So it looks like a "input" overload and the DSP takes car of the internal clipping...
G

Dennis

cadillacfella wrote:

I can turn the gain on the subs all the way up with no clipping.

Are you increasing the gain on the sub itself or in the crossover section of the DRPA+?

Dennis

cadillacfella

Increasing gain on the subs only. All crossover gain settings are 0db.

Gadget

It's not unusual to have to increase the gain of the xover of the subs since they are typically the least efficient, and most power hungry.
G

cadillacfella

Ok. I think I'm all set up correctly. I may run through the procedure again since I made some sub synth changes, but otherwise I think I did it right. I turned the crossover gain on the low end up 4db and was able to reduce the sub gain. Now, I pose this. When I set everything up using using pink noise, I was barely able to get my mixer (Denon DN-X900) to clip so I chose just above 0db level as my clip points (just into the yellow LED). I set everything else up according to the "start here" instructions. When I was finished and played a CD, the channel level was reading much higher than pink noise (+5db as opposed to +1db with pink noise at the same gain setting). Then I noticed that the volume gets really loud really quick as I increase the channel fader. I couldn't push it anywhere near as far up as I could with pink noise. I also noticed that the master fader LED's don't even twitch even when the channel fader is pushed up half way. So, my question is, if I adjust the channel gain on the fly so that the input level remains where I had set it with pink noise, will the rest of my gain structure remain true no matter what I play?

I hope that all made sense

Dra

Made perfect sense. Either the pink track was recorded low, or the music track high, or both. Personally I'd pick a song that is recorded hot and use that to set the max input gain. Pink noise is for setting the output gain of the mixer and all downline gear.

DRA

cadillacfella

Ok, just so I'm certain, please define what you mean by "recorded hot". The pink noise that I was using was the free download from the "start here" forum. And it seemed that any music CD I played was reading higher.

Gadget

Music tracks are heavily compressed and dynamically stagnant...that pink noise have a crest factor of 12dB I believe...The music may have a crest factor of 1-2dB..
So, the gain structure simply has the equipment all talking the same language, I wouldn't worry about the difference in the performance of the two entities...
G

cadillacfella

So, is it a safe assumption that as long as my master level is not clipping, the rest of the system shouln't be either? Provided that I set them up correctly, of course.

Dra

Radical clipping at the source input can cause major problems, but generally, if you are not clipping at the mixer's output, you are fine. As you said, assuming......

DRA