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How Much Was Left? Mixers (Analog)
Old 6th April 2019
  #1
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JayTee4303's Avatar
How Much Was Left?

Street party last night, I had a Zed-10, 2 UPA's and 2 900 subs.

DJ was feeding me clean stereo. (As far as I can tell, some current music includes noises I'm just not sure about.)

I PFLed his feed, one at a time, zeroed the channel fader, and brought the meters up to zero w input trim. During the show, I had the master fader at zero, and held the meters anywhere from zero to plus 6dB, with a very occasional +9 blip. The meter LEDs at plus 12 are red.

Was that it? All the system could safely deliver? I know Meyer tops are considered to have a lot of headroom, but the limiting factor here seemed to be the mixer.

Second question, subs on an aux, how to meter?

My supervisor told me before the show that he typically runs the 900s at minus 9-12, compared to the tops, as the UPAs don't quite equal the 900's output.

I had each channel aux at "minus 3", one mark below unity. Aux master ran minus 3 to minus 6, depending on program material and the desk's main meters.

Any way to meter subs on an aux?

No red lights all show, desk or speakers. No distorted audio, no magic smoke.

I will need to discuss the show intelligently come Monday, and my gut feel is that the rig was a bit underpowered for an outdoor, downtown gig.

Not complaining, I know the promoter's budget determines what we send out.

Phone apps measured about 105, and 102 dB SPL at 10 feet from stacks, while a rock band I work with generally runs 106-108 in clubs.

What can you tell me?
Old 6th April 2019
  #2
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Quote:
Originally Posted by JayTee4303 View Post
No red lights all show, desk or speakers. No distorted audio, no magic smoke.
Well then, you could have certainly pushed it harder. Exactly how much harder, for how long, and with what spectral content is unknown . . . but . . .
Quote:
Originally Posted by JayTee4303 View Post
I will need to discuss the show intelligently come Monday, and my gut feel is that the rig was a bit underpowered for an outdoor, downtown gig.
If the gig "felt" this way, it was almost certainly because you didn't have the coverage you needed, not the raw SPL. Coverage is determined by the loudspeaker's directivity characteristics, and while the UPAs are fantastic products, Meyer still faced the same challenges based on the frontal area of their horn, and the crossover frequency, as everybody else who designs a 12" 2-way top.

By your assessment, I think what you needed was a pair of UPQs.
Old 6th April 2019
  #3
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Wyllys's Avatar
 

Your description on the setup is fairly vague, but going on the stated SPL of 105dB @ 10 feet, you should have plenty left. At full output those speakers should be capable of hitting transient peaks of 123dB at 10 feet. Even if you discount it for "usable" SPL (long term) you should measure at least 113dB @ 10 feet. My old EV T-series rig with the same specs as the UP's would hit peaks of 103dBa measured at 60 feet.

Something's amiss, either with your settings or your measurements. The ZED is capable of +16dBu clean output like most mixers, so you're not really limited there. My guess is the UP input sensitivity wasn't set correctly.

Last edited by Wyllys; 7th April 2019 at 12:12 AM..
Old 7th April 2019
  #4
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Pro Sound Guy's Avatar
 

Your little knob settings mean nothing unless you take the time to set your gain structure in your system.
There is plenty out there on the net on how to set a sound system gain structure for your reading pleasure.
SydAudCon is one of them.
Old 7th April 2019
  #5
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Not familiar w any input sensitivity settings on either box. Stock input modules on both, no RMS setup.

The Zed was as close to max as it would go without clipping, per the meters.

I did notice, not till today, that the main meter legends read 0, green, +3, yellow, +6, yellow, +9, yellow, and +16, red..

I assumed red would be +12, and held the board to occasional peaks, one step below clip, at +9. With the DJ and guest DJs scratching, and adding fx, staying out of the red seemed a safe bet.

Nice to know... now... better late than never, that there's a full 6 dB between the two top tiers of the meter. Not that I'd take a chance blowing up my bosses Meyers, operating "in the dark" between meter segments.

The promoter loved it. The DJs loved it. They set me up in the center of the street, facing crossways, 10-20 story buildings both sides.

I had to pull the highs maybe -4 or -5, and had a 3 dB cut at about 1.5 to quell some harsh. Tops splayed maybe 25 degrees off axis. I used the inboard sides of the horn soread, off the building facing me, as 'center fills", and got decent coverage to about 180 off the outboard edges of the horns.

I'm guessing the harsh was a product of DJ EQ, and some selective reflections off glass and concrete building fronts.

Come Monday, I'll simply ask what policy is regarding how hard to push.
Old 7th April 2019
  #6
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Quote:
Originally Posted by Pro Sound Guy View Post
Your little knob settings mean nothing unless you take the time to set your gain structure in your system.
There is plenty out there on the net on how to set a sound system gain structure for your reading pleasure.
SydAudCon is one of them.
"Knob settings mean nothing."

"Learn gain staging."

Classic.

My intro to FOH desk setup was via Marty McCann around 1985... when you were... how old?

Sonny?

Recent review session w Robert Scovill makes it clear them little lectronz and photonz foller the same rules now as 30 years ago.

YouTube



Tell you what. Steada taking your own words literally, I'll give you the benefit of the doubt, assume you skimmed the post, missing the meaning IN those settings, cuz it's that time of year for you, and they're workin you half to death, too..

This time.

I DO watch S/N ratios carefully, one is all you get.

Capisce?
Old 7th April 2019
  #7
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Wyllys's Avatar
 

Which input module is installed on those UPA's? If they sent you out without the attenuating module, it's their fault. If it did have the attenuating module, I'm afraid it's on you.
Old 8th April 2019
  #8
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Quote:
Originally Posted by JayTee4303 View Post
"Knob settings mean nothing."
Without a scientific reference your knob settings do not actually mean anything in the grand scheme of things. I'm sure Robert Scovill said as much in his seminars, the meter readings would be a more meaningful reference, but apparently you have all the answers so I'll leave it right here...
Old 8th April 2019
  #9
Gear Addict
Quote:
Originally Posted by JayTee4303 View Post
My intro to FOH desk setup was via Marty McCann around 1985... when you were... how old?
It's a mistake to assume you're the biggest fish in the pond.


With regards to how much headroom you had left, we can do a little detective work and figure that out.

For the record, you were using a pair of 12" 2-way boxes, and a pair of 18" subs. All active.


The Meyer UPA specs show that 0dBV continuous average is typically the onset of clipping for music and pink noise.

It took a little reading around, but I've concluded that pink noise has a 12dB crest factor. That means that the UPA can accept instantaneous peaks of +12dBV before clipping.

You can use the tools here: dB dBu dBFS dBV to volts audio conversion digital - calculator volt to dBu and dBV dB mW SPL dB decibels 0 dBFS - convert dB volt normal decibels relatioship relation explanation analog audio absolute level true rms convertor converter decibel to dbfs
to convert to dBU or anything else you want to check.

You'll then know how close you were to hitting the limiters.


With regards to how much headroom you have for the subwoofers, the specs need a little more work:

The "Nominal input sensitivity" suggests that +6.0dBV continuous average will be sufficient, but then the "Input Level" spec requires +20dBV. Perhaps they used a test signal with a 14dB crest factor.
Intuitively, though, it looks like you can push more signal into the subs than the mains before they limit.


However, the key to figuring out how much headroom the subwoofers had is this: program material.

It should be quite clear that an acoustic duo will have the main speakers into limit before the subs even get warm, and a dubstep artist will have burnt the subs out well before the main speakers get close to limit.

Since you haven't really specified the program material, it's impossible to say how much headroom the subs had left.


I hope this is enough information to be getting on with.


Chris
Old 8th April 2019
  #10
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not enough detailed info regarding measurement, possibly a level mismatch in the analog domain (meyer expects a far higher input than a&h can deliver) and/or not enough rig for the gig...

get an external level meter (needs also to be matched...)
Old 8th April 2019
  #11
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Quote:
Originally Posted by chris661 View Post
It's a mistake to assume you're the biggest fish in the pond.


With regards to how much headroom you had left, we can do a little detective work and figure that out.

For the record, you were using a pair of 12" 2-way boxes, and a pair of 18" subs. All active.


The Meyer UPA specs show that 0dBV continuous average is typically the onset of clipping for music and pink noise.

It took a little reading around, but I've concluded that pink noise has a 12dB crest factor. That means that the UPA can accept instantaneous peaks of +12dBV before clipping.

You can use the tools here: dB dBu dBFS dBV to volts audio conversion digital - calculator volt to dBu and dBV dB mW SPL dB decibels 0 dBFS - convert dB volt normal decibels relatioship relation explanation analog audio absolute level true rms convertor converter decibel to dbfs
to convert to dBU or anything else you want to check.

You'll then know how close you were to hitting the limiters.


With regards to how much headroom you have for the subwoofers, the specs need a little more work:

The "Nominal input sensitivity" suggests that +6.0dBV continuous average will be sufficient, but then the "Input Level" spec requires +20dBV. Perhaps they used a test signal with a 14dB crest factor.
Intuitively, though, it looks like you can push more signal into the subs than the mains before they limit.


However, the key to figuring out how much headroom the subwoofers had is this: program material.

It should be quite clear that an acoustic duo will have the main speakers into limit before the subs even get warm, and a dubstep artist will have burnt the subs out well before the main speakers get close to limit.

Since you haven't really specified the program material, it's impossible to say how much headroom the subs had left.


I hope this is enough information to be getting on with.


Chris
That's a lot to work with, thanks.
Old 8th April 2019
  #12
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If the company provides the system based solely on budget...nobody complained, you didn't blow up the system and it performed well, except for you thinking it was a little weak, what is the purpose of this exercise? If this is just about you learning about whats going on under the hood of the system, you will have to understand the concepts touched on by chris661 and you will have to measure (in the absence of accurate metering) as suggested by deedeeyeah.
Old 8th April 2019
  #13
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Here's a pic for reference showing the UPA rear panel options, standard and attenuating modules. Which did they give you? In the text pic note the info regarding limiting...
Attached Thumbnails
How Much Was Left?-image.png   How Much Was Left?-image.png  

Last edited by Wyllys; 8th April 2019 at 02:18 PM.. Reason: Add pic.
Old 8th April 2019
  #14
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Quote:
Originally Posted by Wyllys View Post
Here's a pic for reference showing the UPA rear panel options, standard and attenuating modules. Which did they give you? In the text pic note the info regarding limiting...
No attenuation. Thanks for the re-read on limiting. First time I scanned it, I came away thinking two seconds of limiting would put it in thermal shutdown.

Ooops!

:-)
Old 9th April 2019
  #15
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Quote:
Originally Posted by JayTee4303 View Post
No attenuation. Thanks for the re-read on limiting. First time I scanned it, I came away thinking two seconds of limiting would put it in thermal shutdown.

Ooops!

:-)
So you're saying the installed module was not the one pictured underneath the panel, and no pot numbered -12 to 0 going clockwise.

I think this next pic from the spec sheet explains things. It is still uncertain exactly how much output voltage you were sending from the ZED, but this explains how much voltage the speakers are set to handle for max output. The ZED is capable of a max output of +21dBu which would match up with Meyers stated voltage required to engage the UPA limiters...a theoretical match for mixer max output and speaker max input.

P.S.

I also wonder about the accuracy of the SPL app you were using.
Attached Thumbnails
How Much Was Left?-image.png  

Last edited by Wyllys; 9th April 2019 at 02:23 AM..
Old 9th April 2019
  #16
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Quote:
Originally Posted by Wyllys View Post
I also wonder about the accuracy of the SPL app you were using.
Me too. If you clip the phone mic to square waves, it might still only read 105dB.


FWIW, I had a quick look at the specs for the desk. 4ms rise time on the meters means the actual peak levels could've been anything.

Chris
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