Gain Structure: Does this sound correct?

go2ldook

Followed the gain structure instructions. Since it is a little different for the DriveRackPX, can you please confirm I am good:
1) Played the pink noise generator that was suggested. The volume of the player (on my computer, connected to my mixer via a Motu Ultralite interface) was at 100%. The instructions did not indicate the level of the source really mattered though.
2) Enabled the PFL on the channel and turned up the gain as instructed. On my Allen & Heath MixWizard 3 16:2, I turned it up to just below clipping (+9)...clipping red light is +16.
3) I deactivated the PFL. As far as I can tell, my mixer has no AFL switch. With the master fader at 0, the meter was at +6. I turned up to just barely getting a clip, master fader was at about +5.
4) Looked at the DriveRackPX. Here is where the instructions on this site are confusing:

"if the meters on the mixer are at just clipping and your using +4 and the meters on the Driverack are anywhere above the 0vu but below the clip light your fine... there is no input mixer to adjust... If the signal is low try the -10 setting and see if that gets you to a more appropriate setting."

OK, my mixer meter was just clipping. But on the DriverackPX, 0 IS clipping. The input meter says "Headroom dB" and runs O=red/clip, 6=yellow, 12-36=green. There is no "above the 0vu but below the clip light". Is "Headroom dB" something different than 0vu?

Anyway, with my DriverackPX set at +4dB(pro level), and the mixer just clipping, I had the DriveRackPX input meter just clipping. Backing off my master fader to 0, that put my mixer meter bouncing into the 2nd yellow (+6), and the DriveRackPX bouncing nicely into the only yellow on the input meter, also +6.

I assume that is all good?

Dra

go2ldook wrote:

Followed the gain structure instructions. Since it is a little different for the DriveRackPX, can you please confirm I am good:
1) Played the pink noise generator that was suggested. The volume of the player (on my computer, connected to my mixer via a Motu Ultralite interface) was at 100%. I don't like anything at 100%, though for this it probably doesn't matter.The instructions did not indicate the level of the source really mattered though.
2) Enabled the PFL on the channel and turned up the gain as instructed. On my Allen & Heath MixWizard 3 16:2, I turned it up to just below clipping (+9)...clipping red light is +16.You have now set the gain for that one input channel (for that input source). Just remember that gain setting is really divided into 2 sections...within the mixer (inputs to outputs)and after the mixer (outputs - driverack - amp). Til now you have only dealt with the onboard and really does not affect the "system gain structure". GHowever, you really need to set the channel gain to -0- PFL for this so you have a reference for -unity- on the channel fader.
3) I deactivated the PFL. As far as I can tell, my mixer has no AFL switch.With all channel PFLs off you can monitor the output busses, but the meters will be L&R outputs only. With the master fader at 0, the meter was at +6. I turned up to just barely getting a clip, master fader was at about +5. Now with the channel fader at -0- and the master at -0-, the meters should read -0-. This verifies -unity- through the mixer. Now, raise the output faders until you see the clip indication on the PX input. ***Maybe Gadget can verify this... Whether the "clip" indicator on the PX is actually clipping or just below clipping, say 3db below.*** Either way, if you have to run your system at -3db clipping, you need more system. Whatever the situation you need to burn that mixer output LED into your brain and NEVER go past it (actually don't to, and better yet, don't get close.
4) Looked at the DriveRackPX. Here is where the instructions on this site are confusing:

"if the meters on the mixer are at just clipping and your using +4 and the meters on the Driverack are anywhere above the 0vu but below the clip light your fine... there is no input mixer to adjust... If the signal is low try the -10 setting and see if that gets you to a more appropriate setting."

OK, my mixer meter was just clipping. But on the DriverackPX, 0 IS clipping. The input meter says "Headroom dB" and runs O=red/clip, 6=yellow, 12-36=green. There is no "above the 0vu but below the clip light". Is "Headroom dB" something different than 0vu?

Anyway, with my DriverackPX set at +4dB(pro level), and the mixer just clipping, I had the DriveRackPX input meter just clipping. Backing off my master fader to 0, that put my mixer meter bouncing into the 2nd yellow (+6), and the DriveRackPX bouncing nicely into the only yellow on the input meter, also +6. 6db headroom is satisfactory, but 9db is better. See if you can get by with peaking at +6db (occasional illumination), or less.

I assume that is all good?

DRA

go2ldook

Dra wrote:

You have now set the gain for that one input channel (for that input source). Just remember that gain setting is really divided into 2 sections...within the mixer (inputs to outputs)and after the mixer (outputs - driverack - amp). Til now you have only dealt with the onboard and really does not affect the "system gain structure". GHowever, you really need to set the channel gain to -0- PFL for this so you have a reference for -unity- on the channel fader.[/color]

Yes, but there is really no point to setting the gain for every input channel using the pink noise, because again...the gain level of the pink noise source may vary from, for example, the gain level of a microphone. You will still have to do a per channel gain level when you set up at the venue for each channel. Or you can do it ahead of time at home...but my point is, each channel will vary depending on the source. It would seem to me the pink noise exercise is mainly to get to unity between the mixer/DriveRackPX and the DriveRackPX/Speakers. Correct?

Dra wrote:

3) I deactivated the PFL. As far as I can tell, my mixer has no AFL switch.With all channel PFLs off you can monitor the output busses, but the meters will be L&R outputs only.

Understood. But those are all that matter for the purpose of the DriveRackPX. The only other outputs are the monitors, and since they do not go through the DRPX, I would just make sure that the Aux Send is at unity with my 231 GEQ and that it, in turn, is not driving the powered monitor speakers to clipping.

Dra wrote:

Anyway, with my DriverackPX set at +4dB(pro level), and the mixer just clipping, I had the DriveRackPX input meter just clipping. Backing off my master fader to 0, that put my mixer meter bouncing into the 2nd yellow (+6), and the DriveRackPX bouncing nicely into the only yellow on the input meter, also +6. 6db headroom is satisfactory, but 9db is better. See if you can get by with peaking at +6db (occasional illumination), or less.

DRA

Yep. I am good on that. With channel and master faders at 0, the DRPX input Headroom is at 12dB.

go2ldook

So on the monitors, I run them through a dbx 231GEQ. For setting the gain between the mixer and the GEQ, would you adjust with the pink noise so the Aux send knob for the monitor lights up the output level meter on the GEQ at 0dB when the knob is about 3/4 of the way up (the unity mark)? This EQ unit has an input gain knob, and I basically adjusted it, with the Aux send knob at its unity mark, so that the +10 on the output level just started to blink, then backed down until it stopped so I was right at 0dB. Next I will add speakers and have them set to below clip.

Dra

go2ldook wrote:

Dra wrote:

You have now set the gain for that one input channel (for that input source). Just remember that gain setting is really divided into 2 sections...within the mixer (inputs to outputs)and after the mixer (outputs - driverack - amp). Til now you have only dealt with the onboard and really does not affect the "system gain structure". GHowever, you really need to set the channel gain to -0- PFL for this so you have a reference for -unity- on the channel fader.[/color]

Yes, but there is really no point to setting the gain for every input channel using the pink noiseEvery input channel? Where did you get that idea?, because again...the gain level of the pink noise source may vary from, for example, the gain level of a microphone. You will still have to do a per channel gain level when you set up at the venue for each channel. Or you can do it ahead of time at home...but my point is, each channel will vary depending on the source. It would seem to me the pink noise exercise is mainly to get to unity between the mixer/DriveRackPX and the DriveRackPX/Speakers. Correct?Correct.

Dra wrote:

3) I deactivated the PFL. As far as I can tell, my mixer has no AFL switch.With all channel PFLs off you can monitor the output busses, but the meters will be L&R outputs only.

Understood. But those are all that matter for the purpose of the DriveRackPX. The only other outputs are the monitors, and since they do not go through the DRPX, I would just make sure that the Aux Send is at unity with my 231 GEQ and that it, in turn, is not driving the powered monitor speakers to clipping. Understood. Just stating that you can monitor (phones) those other output

Dra wrote:

Anyway, with my DriverackPX set at +4dB(pro level), and the mixer just clipping, I had the DriveRackPX input meter just clipping. Backing off my master fader to 0, that put my mixer meter bouncing into the 2nd yellow (+6), and the DriveRackPX bouncing nicely into the only yellow on the input meter, also +6. 6db headroom is satisfactory, but 9db is better. See if you can get by with peaking at +6db (occasional illumination), or less.

DRA

Yep. I am good on that. With channel and master faders at 0, the DRPX input Headroom is at 12dB.

Sounds like you have it under control.

Dra

go2ldook wrote:

So on the monitors, I run them through a dbx 231GEQ. For setting the gain between the mixer and the GEQ, would you adjust with the pink noise so the Aux send knob for the monitor lights up the output level meter on the GEQ at 0dB when the knob is about 3/4 of the way up (the unity mark)? This EQ unit has an input gain knob, and I basically adjusted it, with the Aux send knob at its unity mark, so that the +10 on the output level just started to blink, then backed down until it stopped so I was right at 0dB. Next I will add speakers and have them set to below clip.

On the same channel you set up at -unity-, set the aux and aux master output knobs to -0- and connect that output to the EQ. Adjust the input of the EQ to -0- on the EQ's meter. Ring the monitor out and re-adjust the EQ's input to -0- to compensate for the cuts.

Powered speakers will typically -unity- out about 12 oclock. Keep in mind most powered speakers do no clip, they limit. Semantics, I guess, but still best to avoid either.

DRA

go2ldook

My powered speakers have "Line" level at 9 oclock and +4dB level at 12 oclock. After going through the gain structure for the system, I have now hooked it to my speakers. Just beyond the 11 oclock mark the limiter light begins flickering. I know you said above that unity gain is generally at the 12 oclock setting on powered speakers. Should I be setting output gain in the DRPX somehow so the speaker limit light is not flickering at 12 oclock, or is it fine just to set the speaker level at about 10 oclock and go with it?

Dra

You left out a key word. "About" 12 o'clock.

What I do (situation may well be different that you), is I will play a CD (but paused) and adjust the speaker's input to an acceptable hiss for the situation. For me that is 10-11 o'clock. You will have to make the final call on whether you what the speakers to limits before, at the same time, or after you reach the "max output" you want from the board.

DRA