Delay and ambient temp setting

[Pro Sound Guy]

Im wondering if Andy or Don or somone can give me an idea how in the world delay and polarity can be done with out a test signal and microphone? Maybe I missed something in this manual. Please look at page 9 of the manual and see Dly-Corr./Auto-Align.

Is this some kind of voodoo or legit? Thanks

 

http://www.behringer.com/assets/dcx2496_p0036_m_en.pdf

 

[Craig Vecchione]

That page does mention test tones, and that the process can't be executed if the levels are too low, but nothing seems to exist in writing about how the thing hears them. If you look at the block diagram, Input C seems to mention "@AUTO-ALIGN mode". So maybe they forgot to mention this....

 

 

[trevcda]

They kind of touch on the measurement mic input with phantom power on page 5, number 24, but I've yet to read where they bring it all together with test tones anywhere in the manual. I'm sure the ambient temp correction is just a formula applied to the delay setting. I love how the parameters allow for -4f to +122f. Who runs sound in -4f?

[Pro Sound Guy]

Ok another well written manual.

 

[Pro Sound Guy]

Yea page 5 says C can be used as a mic input with phantom as long as auto align is on.

So its not some kind of majic unexplained voodoo.

[agedhorse]

Generally, for the distances we are dealing with and the physical alignments we have to contend with, the temperature is way too far to the right of the decimal point to worry about for most reasonable temperature swings. You have to remember that temperature is just one variable, a small one at that. Just different measurements positions in the typical seating areas will cause much greater differences which are much more significant but much less marketed at.

 

Think about the end user of this kind of product, it's a bottom end product targeted at mostly bottom end users who like to think they know more about what they are doing than they really do. They are the ideal target for this kind of marketing. I have customers like this who fret the most insignificant details then show up to the gig on the wrong day, without the NECESSARY tools to do the job much more correctly, but by god they have all matching tie wraps on their cables (that they spent hours color coordinating) and spent hours, days or weeks worrying about the color of their cases. Un-freekin' believable.

[dennis a]

Think about the end user of this kind of product, it's a bottom end product targeted at mostly bottom end users who like to think they know more about what they are doing than they really do.

 

I don't disagree with this but keep in mind that the Behringer Ultradrive is a knock off of the BSS Omnidrive with the same feature set. With a price tag of $2000- $2500 I haven't heard too many people refer to the Omnidrive as "bottom end"

[Dogoth]

Temperature and time delay??? :-)

 

Ya sure. OK I admit I didn't look at the manual but if you set it up in the environment you're going to use it in, how are the temperatures going to change all that dramatically? About the only thing temperature is going to effect is the extremely high end (say 8k and above) and even this will be about as much as moving your calibration mic a few cm to the right or left. Ever hear how the high end gets phasey (is that a word or should I use fuzzy? :-) on a windy day? This isn't the air motion blowing the sound around but rather varying temperature gradients between the speaker and your ears that is CAUSED by the wind. What about AC or heating turning on and off? Won't this effect the phase alignment too (I'm being sarcastic and pragmatic here :-)?

 

Maybe I'll design a thermo sensitive constantly variable, automatic phase alignment tool to sell to the audiophile market (it would of course come with a bi-neural calibration mic and a head brace for the listener just to make sure that sweet spot doesn't move :-). It's kinda like women and stiletto heels. It's amazing the torture people will go through to be fashionable ;-).

 

Sorry I just HAD TO :-)

 

Cheers

 

 

[Pro Sound Guy]

Time alignment between the drivers and polarity is pretty important. This unit has nothing but 5 star ratlngs.

I am going to try it over my analog active xover. If it turns out it sucks I will not use it.

This has way more cabability then the DBX driverack. I ordered one and it will be here this week.

It has a decent parametric and can do 48db slopes, and all the rest.

You can also run a complete foh system and run a stereo out for rear delays. Mono subs, center fill you name it.

I understand the bitch people have about B but the X32 is selling like hot cakes.

Thanks for the tips and sorry for missing the mic input info earlier in the manual.

 

 

[agedhorse]

 

I don't disagree with this but keep in mind that the Behringer Ultradrive is a knock off of the BSS Omnidrive with the same feature set. With a price tag of $2000- $2500 I haven't heard too many people refer to the Omnidrive as "bottom end"

 

Yes, but you also don't see (many) folks touring with this product and passing it off as an Omnidrive either.

 

I am specifically referring to the Behringer product and even more specifically to those customers specifically marketed to. For example, I am seeing some significant caution being used against the X-32 board, not for the board itself or the performance but for the folks who buy an entry level PRICED board thinking they know the business then falling flat on their face again and again leaving the act (or the promoter) in some serious trouble as the sound contractor fails to deliver what's expected of them.

 

It's a very awkward position for a touring act to have to deal with. It used to be that it a company invested in say a PM-3K or 4k and necessary outboard gear, the chances were pretty good that the company was reasonably committed to the industry and their reputation. Just recently, a local provider folded up after a string of relative failures and to him it was no big deal (other than a little of daddy's money) and in fact this guy insulted the act by laughing about their troubles with his gear (or lack of it). Cost of entry helps keep the riff raff out.

[Dookietwo]

I can see Temperature and Humidity effecting Delay line stacks in large outdoor setups where things have changed between system setup and concert performance time. This may be more of what this is designed for. Thousands of people will effect the temp and humidity for sure. But having temperature effect alignment between a mid and sub which would effect both equally at the crossover point. I don't see the temperature change being different at a sub and a midrange location. Both would be effected equally.

I'd be more worried how the delay time is found. Is it Impulse Time or does it look for a Phase Alignment at and around the crossover point?

[Craig Vecchione]

Yea page 5 says C can be used as a mic input with phantom as long as auto align is on.

So its not some kind of majic unexplained voodoo.

 

Thanks for spotting that. I'll have to disagree about it not being unexplained as a mention isn't an explanation, and if we consider the likely users as Andy has been discussing, they need to have things explained.

[agedhorse]

I agree with Dookie here, I suspect that the difference MAY become significant over long distances with great temperature differences. Again, probably not something that would be encountered by the average user of this product.

[Pro Sound Guy]

I got curious and wanted to know why. Speed of sound changes with temp. So I wanted to see if other

processors offered the temp setting and why.

I found this on a high end processor. It seems temp is used as a factor in calculating delay times.

I still dont know why they need this for calculation.

 

The EAW UX3600 Digital Signal Processor is a 1RU 19" rackmountable DSP processor designed for PA speaker management in touring, installed, and live sound applications. The unit features three analog inputs and six analog outputs over balanced XLR connectors and provides custom designed algorithms for setting EQ filters, delays, gain levels, polarity and crossovers. The signal processing design provides extensive user control and takes into account factors such as room temperature when calculating delay times and humidity when equalizing for air loss to accommodate for the way that the speed of sound changes under different environmental conditions.

 

Temperature Compensated Delay

Accounts for the change in the speed of sound at different temperatures when delay aligning multiple speakers

 

 

[Dookietwo]

This is just example numbers but it may help you see.

You have a delay line 100 feet out from the main stack. It takes 89ms to delay your delay line stack to the main PA when its 60 degrees at 9 am that morning. You enter 60 degrees in your processor. Now at 2 in the afternoon its now 90. The sound travels faster in the warm air. So now the sound from the Main PA reaches you delay stack Before 89 ms. Standing by your delay stack you hear sound from the main pa first then sound out of the delay line a little later. Sounds weird.

So you go to your processor and put in 90 degrees. The processor has a rough idea of the speed change between 60 degrees and 90 degrees and corrects it by taking the right amount of delay off the delay line.

 

That night its a cold one. Temps drop to 45 degrees. Now standing by your delay line sound from the main pa arrives late so you hear the delay line sound first then the mains. Yuck , so you enter 45 degrees into the processor and it adds more delay to the delay stack so the mains and delay line blend together.

 

By having this you don't have to setup microphones and pay the expense of having a sound tech realign the system. This just gets you "close" but better than no adjustments at all.

I have heard of processors that also account for humidity which changes things as well.

 

Dookietwo

 

https://www.nde-ed.org/EducationResources/HighSchool/Sound/tempandspeed.htm

[Dookietwo]

This is just example numbers but it may help you see.

You have a delay line 100 feet out from the main stack. It takes 89ms to delay your delay line stack to the main PA when its 60 degrees at 9 am that morning. You enter 60 degrees in your processor. Now at 2 in the afternoon its now 90. The sound travels faster in the warm air. So now the sound from the Main PA reaches you delay stack Before 89 ms. Standing by your delay stack you hear sound from the main pa first then sound out of the delay line a little later. Sounds weird.

So you go to your processor and put in 90 degrees. The processor has a rough idea of the speed change between 60 degrees and 90 degrees and corrects it by taking the right amount of delay off the delay line.

 

That night its a cold one. Temps drop to 45 degrees. Now standing by your delay line sound from the main pa arrives late so you hear the delay line sound first then the mains. Yuck , so you enter 45 degrees into the processor and it adds more delay to the delay stack so the mains and delay line blend together.

 

By having this you don't have to setup microphones and pay the expense of having a sound tech realign the system. This just gets you "close" but better than no adjustments at all.

I have heard of processors that also account for humidity which changes things as well.

 

Dookietwo

 

https://www.nde-ed.org/EducationReso...mpandspeed.htm

[Pro Sound Guy]

Ok great now I get it! So I have to ask why cant you "plug" in a temp/humidity sensor to the unit and have it

monitor the temp and humidity for you and "auto" adjust! I suspect that would work better then having a unit in a rack back stage. You could have a temp/humidity sensors plugged in by the mix out in the crowd and have it feed

the processor.

It will come one day? Thanks for your input Dookie

 

 

[wesg]

The new breed of speakers with built-in networking could actually monitor this and auto-compensate in the field.

 

Are you listening, Line 6?

 

Wes

[dboomer]

Easy to do, but hard to sell

 

There is a cost involved so you have to be able to charge for it. When you solve problems tat customers don't even know they have they are reluctant to pay for them. Our StageScape/StageSource mixer and speakers solve a great number of invisible problems without customer intervention but the average customer standing in front of a stack of things that "look the same" doesn't understand the difference and only sees the higher price.

[Craig Vecchione]

I don't see this being anywhere near needed. The average user can't set a limiter and has no clue what a HPF does. Setting delay based on temp/hum is way to the other side of the decimal point, as Andy stated a page ago...

[Dogoth]

With all of the trade offs involved in SR, I'd think a temperature sensor is more of a gimmick than a useful device (not saying the unit is over all bad - just that particular whistle). In reality it should be a barometric pressure sensor since when the temperature changes, so does the density of the air (just like elevation). What if a hi pressure front moves in between SC and showtime but the temperature remains the same (not likely but........)? I just don't quite buy it as being important (or even noticeable). Can the engineer mix? Is the band good? How are the acoustics of the room? IMHO these are what will predict good audio far more reliably than temperature sensitive time alignment.

 

Just call me pragmatic.

 

Cheers

[Pro Sound Guy]

When a delay tower can change 10ms in time at a big venue from temp change outside then it is a big deal. Inside not a big deal.

 

 

 

 

[agedhorse]

It's even less of a big deal on a delay tower because the time coherency of the typical listener position is WAY lower than the 10mSec impact might have. By a factor of 2 or 3.

 

 

 

When evaluating these things, you have to determine the range of impact of each variable. If the listening environment is +/- 30mSec and you make a change of 10mSec, some listeners may see an improvement while others see worse conditions. Without knowing the distribution within the range, the change may make things worse for more people than it gets better for.

[Pro Sound Guy]

I thought of that a while after I put the post up (audience location) to tower and thought ...ya know Aged is gonna spank me for that post

My question is if the temp setting on a processor is not real important then why do some processors have this as a setting and some even humidity settings to boot.

So basically delay loudspeakers are a happy medium setting? Set it and forget it?

Sorry to drag this all out but I am curious.

 

 

 

 

[agedhorse]

I didn't bust you, in fact it's a valuable part of the discussion IMO.

 

Yes, the setting of delay times for a delay tower application is based on an indeterminate equation... there is no single answer and there can never be. There is a range or a set of answers based on the location of the listeners impacted by the delay tower. Once you accept that there is no single right answer, things get a hell of a lot easier going forward (except for the OCD folks).

 

What's important is to recognize the range that is valid by understanding the spatialness of the equation (meaning that you would solve the delay equations by picking points around the boundery of the target coverage area.) and recognizing this range of solutions and then picking a point within the range that represents most of the people most of the time. you may choose to cheat the number one way or another based on the expectations of changes in the listening environment (ie. sitting is shade that moves over time, or the expected change in temperature). Overall, I think there are generally more productive ways to spend your time and energy... locating the nearest bathroom, insuring that you have water, shade, food, adequate labor, etc.