Question about "System Setup and Gain Structure"

bgordon

In Appendix A of the DriveRack PA manual, there are instructions for setting up amplifiers for maximum gain structure using the clip indicators of the console and of the amplifiers.

Will the described procedure work if our speakers are not among those available in the DriveRack configuration (we used Custom here)? The amplifiers are available.

Since the speakers were not available for selection, and the DriveRack doesn't know what speakers we are using, would it be better to take the DriveRack out (connect soundboard directly to amplifiers) to adjust the input attenuators of the amplifier, and then put the DriveRack back in and adjust the DriveRack gains with the Xover settings?

Maybe I'm not understanding something (sorry)...

Thanks. -bg

Dra

viewtopic.php?f=61&t=959

Detailed instructions.

DRA

bgordon

Thanks for the link. I did a search on "gain structure", but nothing came up. Dunno why.

So if we follow this procedure and set the gains on the soundboard, the amplifiers, and the DriveRack as suggested, and we find that the sound volume coming out of the PA system is way too loud, where (at what piece of equipment -- in the DriveRack or at the amplifier) do we back it down?

Thanks.

Dra

You've missed the big picture. The purpose of setting the gain structure (achieving "Unity") is to not allow a down-line piece to reach clipping unless a piece up-line has already begun to clip. For example... the mixer output may be clipping, but the amp are still below clipping. Obviously, you are now at max volume. To have less volume, simply reduce the master faders. Not the individual channel gains. Not the driverackx-over gains. Not the amps.

DRA

Gadget

The master faders on the mixing console...Make sure that you get optimum signal on the individual channels... use the PFL and output meters to get a strong channel strip signal. This will insure good signal to noise ratio and a quiet system when at idle.

There are other ways to do the gain structure and you can make it your life's work, but this method has given good results with the least headaches. For digital mixing consoles there is a different path, but there you don't have to worry so much about signal to noise as you do clipping.
Gadget

bgordon

Understood.

Thanks, guys! -bg

dhansen111

When feeding the pink noise signal to the channels, does it need to be line level or can you feed it through an IPOD? Can the pink noise be an MP3 or do you need to keep it a wav file?

Thanks!

Dra

I have heard it said that .wav is best if maintaining the original crest factor is important to you. If not, then the others are fine.

DRA

dhansen111

But, is the headphone out on an iPod going to send too much signal? Or should it be a line level from say the RCA outs on a CD player?

Gadget

You can vary the level of the IPoD AND the input gain so no...
G