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[Issack Andrew]

Hey guys,

The hall I am dealing has really poor acoustics and the client has no budget currently to invest in acoustic treatment. The client just invested in a new mixer (Allen Heath QU32) and called me in to assist with some tuning.

The band generally plays very loud and with the FOH turned off the SPL meter was easily reading 90db from point B, hence why the client wanted the first few rows to be in front of the mains A as things were getting too loud.

I tuned all the 4 monitor mixes on the stage using RTA and pink noise and maybe some EQ adjustments to taste based on the mixes that the band required. No problem with the stage monitor mixes.

Now for the mains, they have a dual 18" sub below the stage that can not be moved because of props / stage design.


The diagram is not to scale



Some measurements:


"A1" to the first set of main speakers "B" is 14 metres.

"A2" (front of stage where sub is located) to mains "B" is 9 metres.

The distance from the second set of mains (fills) "C" to the "B" is 6 metres.

I've been using this calculator to calculate the delays.
http://www.brightonsoundsystem.co.uk/calculator/audio-delay.php

Currently this is what I have set up

I have delayed "B" mains to the front wedges / sub (A2) by 26.24 ms

I have delayed "C" fill mains to the stage (A2) by 43.7ms

None of the wedges or the sub have delays on them but all of that is possible since every output on the QU-32 mixer has a delay option.


Questions:

1. What would you more experienced guys do regarding delays? Can I improve in any ways?

2. I have pink noise / RTA tuned the mains as well. I have placed the mains as high up on the speaker stands as they can go. Coverage is decent (after all the effort put in to delays / tuning) but the lows sound really bad in this hall. 80-100hz range is really sensitive and the kick just doesn't have the punch that you would expect it to have.

3. They have no budget for now so all that I can work with is speaker placement, delays and EQ. Any other suggestions?

Thanks,

Issack 

[Peter Morris]

Hey guys,

The hall I am dealing has really poor acoustics and the client has no budget currently to invest in acoustic treatment. The client just invested in a new mixer (Allen Heath QU32) and called me in to assist with some tuning.

The band generally plays very loud and with the FOH turned off the SPL meter was easily reading 90db from point B, hence why the client wanted the first few rows to be in front of the mains A as things were getting too loud.

I tuned all the 4 monitor mixes on the stage using RTA and pink noise and maybe some EQ adjustments to taste based on the mixes that the band required. No problem with the stage monitor mixes.

Now for the mains, they have a dual 18" sub below the stage that can not be moved because of props / stage design.


The diagram is not to scale



Some measurements:


"A1" to the first set of main speakers "B" is 14 metres.

"A2" (front of stage where sub is located) to mains "B" is 9 metres.

The distance from the second set of mains (fills) "C" to the "B" is 6 metres.

I've been using this calculator to calculate the delays.
http://www.brightonsoundsystem.co.uk/calculator/audio-delay.php

Currently this is what I have set up

I have delayed "B" mains to the front wedges / sub (A2) by 26.24 ms

I have delayed "C" fill mains to the stage (A2) by 43.7ms

None of the wedges or the sub have delays on them but all of that is possible since every output on the QU-32 mixer has a delay option.


Questions:

1. What would you more experienced guys do regarding delays? Can I improve in any ways?

2. I have pink noise / RTA tuned the mains as well. I have placed the mains as high up on the speaker stands as they can go. Coverage is decent (after all the effort put in to delays / tuning) but the lows sound really bad in this hall. 80-100hz range is really sensitive and the kick just doesn't have the punch that you would expect it to have.

3. They have no budget for now so all that I can work with is speaker placement, delays and EQ. Any other suggestions?

Thanks,

Issack 

Firstly the delay varies as you move around the listening field. There is no exact answer just a good compromise.  If for example you are standing exactly at point B you are closer to the sub than the mid-hi speaker ...so you should delay the sub for that listener .... stand somewhere else its different.

Sooo ... you should delay B to the sub at A2 so the mids are time aligned to the subs to minimise cancellation at the crossover frequency (for most of the audience).    Best guess - you should calculate the distances with respect to the centre of the listening area on one side, the centre of the area you are expecting that speaker to cover. (I hope that makes sense  )

As another guess, delay B by about  28 - 30 ms, and also delay C to the sub, i.e. another 17.5ms or about 45 to 48 ms in total. This is more or less what you have done.

Now you can delay the loud back line instruments such as the drums on each channel so the stage spill is in line/time with the PA ... i.e if they are 3M back ... about 9ms on the individual channels.

You can also flip the polarity of the kick and or bass to see which way (polarity) sounds the best.

[David Allred]

A recording of a snare hit on a 2 sec interval will allow you to walk the space of C.  You can chart a hand full of locations as -, =, +, or whatever, then choose a best average as a differential from B.

I have learn here that a little extra delay helps draw the eyes and ears to the stage instead of the delay speakers.

[Roland Clarke]

This is a really difficult situation and as Peter stated, whatever delay you use is going to introduce a significant compromise.  Whatever you do, even if you get it to sound reasonable, the amount of comb filtering from the two speaker positions will likely render desk eq pretty ineffectual.  You don’t give details of other dimensions such as width (I’m guessing that is in the order of 10m judging by the number of seats you placed), or more importantly height.

I would have the mains at the foh stage position close to the sub line, but I would look to get them high.  At present your suggestion although quieter for the first few rows, would not allow them to hear vocals, Keys/acoustic guitars (unless they are using an amp), so you would at least require some centre fill.  I also think that the second speaker placement isn’t far enough back to make it meaningful as a suplimentary system,  I would be looking for it to be at least 12m assuming you have more than 4m of height.  A lot of assumptions, perhaps post some pictures?

[Mike Caldwell]

Careful delaying the input channels, depending where your picking off the monitor mix sends you could be also delaying the input to the stage monitors.

Personally I would not delay the input channels but try delaying the sub back to about the middle of the stage, then delaying the row B speakers back to the sub and finally row C speakers back to row B speakers.

As mentioned the delay times will all be just an average, there's no way to exactly delay for every seat in the house all at the same time.

Tell the band to turn down, that includes amps and stage monitors, drumming technique if acoustic drums.

Also as mentioned a touch of extra delay on speaker row C can help draw the audio perception to the front and the possible need for a couple front fills with at least a vocal mix in them.

[Chris Grimshaw]

I get that it's loud at the front, but if you're putting vocals through the PA, there will be sections of the audience that won't hear the vocals properly at all.
If the main PA speakers are already installed, I'd consider a 10" or 12" centre-fill to cover the first few rows with vocals and anything else that isn't loud on-stage.

Chris

[Dave Garoutte]

Try hard to get them to turn down on stage.

Basic acoustic panels are pretty cheap actually.
panels
Mount them an inch or two off of the reflective wall for best effect.
Cover them with fire retardant cloth.
cloth
I'm working on a DIY kit for this.  Maybe supply finished product eventually.

[Peter Morris]

Careful delaying the input channels, depending where your picking off the monitor mix sends you could be also delaying the input to the stage monitors.

Personally I would not delay the input channels but try delaying the sub back to about the middle of the stage, then delaying the row B speakers back to the sub and finally row C speakers back to row B speakers.

As mentioned the delay times will all be just an average, there's no way to exactly delay for every seat in the house all at the same time.

Tell the band to turn down, that includes amps and stage monitors, drumming technique if acoustic drums.

Also as mentioned a touch of extra delay on speaker row C can help draw the audio perception to the front and the possible need for a couple front fills with at least a vocal mix in them.

With the Qu he is using there is generally not an issue with delay in the monitors. Normally I tap my foldback sends at pre EQ.

[Mike Caldwell]

With the Qu he is using there is generally not an issue with delay in the monitors. Normally I tap my foldback sends at pre EQ.

Yep I have a Qu and normally set up monitor mixes that way as well, just letting him know to set the mix up should he use input delay.


And speaking of mixes how are you running the subs and your delay fills Issack?

[Issack Andrew]

Yep I have a Qu and normally set up monitor mixes that way as well, just letting him know to mix set up should he use input delay.


And speaking of mixes how are you running the subs and your delay fills Issack?

Running B and C main / fills using the matrix sends and running subs using a mix bus (so I can send only kick, bass and some keyboard parts)

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