New Youtube Videos

So I have been busy with new vids, all three mic chat videos with my daughter Sammy are now up:

In video #1 we discuss why there is such a variety of mics and usages
https://youtu.be/_xlvHB7Ggmo

In video #2 we look at the pulse response of various mics and mic types
https://youtu.be/xNtzSsp9V3w

In Video #3 we listen to the pulse tests and chat about mic types
https://youtu.be/-YTfSX1PxLo

Also on the members side of my YouTube, I just posted a video testing an M-Force bolted to some saw horses, from a SuperSub with low frequency tones from a the YouTube low frequency test video.

https://youtu.be/CPobIlqTN58

and here is a link to a video that analyzes that video

https://youtu.be/cq_nRThQm64

Coming soon, a video using in-ears as mics to listen to the inside of my head.

How low does YouTube Go?

Anyone up rocking some ultra super lows?

I made a video to test the low frequency limits of YouTube.

Starts at 30Hz and goes down to 1Hz

Then 1Hz down to .1Hz

And it thats not enough, it keeps going down to pure DC voltage

Then to negative DC voltage and all the way back up to 30Hz.

How low do ya think youtube can go?

How low does your system go?

And I dont stop there, I then downloaded the video from youtube and did a second video where I compare the before and after signals.  Fun fun fun!

Testing In-Ears!

The first in a series of videos diving deep into testing In-Ears is up in the paid Member side of my YouTube channel. I will be releasing at least one per week. So far the videos in various states of completion are:

#1 In Ear Testing
#2 In Ear Specs and Test Gear
#3 Body Resonance vs In Ear Polarity
#4 Audible differences between different In-Ear and Headphone Wiring types

Other ideas for videos in the series I am working on are:

Smaart response of top brand in-ears
Actually hear the various in-ears over YouTube
Test Max output
Test distortion of in-ears
Tear apart and in-ear and look at the Armature
Pulse Response of armature vs driver based in-ears

Cool cool, here is the link to video #1

Lets test some In Ears!

I am doing a new youtube series where I will be testing and comparing in-ear units from L-Acoustics, JH Audio, Ultimate Ears, Futuresonics, Stealth Sonics and more.

This will be fun doing a deep dive, so far I have recorded 4 videos: over all description video, specs and details about the in ears and the Audx TM-2 measurement unit, polarity of our body vs in ear polarity, and the impacts of differing in ear cables on stereo imaging.

Cool cool, more posts soon.

Hello Hello!

Ok, its been a long while since I have blogged. Recently my focus has been on my YouTube channel where I have been actively posting about one video per week.

What I am thinking to try and do is to use this blog as a place to suppoet the YouTube channel and chat with channel members, post additional info and such.

Lets give a shot! Going to post a link to the blog on my youtube channel, shoot me a comment and let me know what cha think.

Roommates

It feels like I’m trapped with a bunch of roommates in some alternate logic nightmare overhearing an endless argument.

Someone wanted to clean the house before the party, someone wants to clean after the party, and someone wants the party in the garage.

Meanwhile the smell of smoke conitinues to waft through the house, there is a strange truck in the driveway, and we all hear loud noises in the garage, oh and there have been reports everyday of an arsonist rapist burglar that has burned down 7 houses in the neighborhood already.

So, one of goes on to say, if y’all did not argue with me, we’d already be having the party and the burglar would never have come. Another says, oh, I saw that burglar guy out back earlier, I love him, he’s gonna give me a flying cat that shits gold coins so I gave him the keys to the garage. And another says, let’s just move the party into the living room. But what about the burglar? Aww, there will always be burglars, what about the fire? Oh, there will always be fires. And the rapist in the house? Just lock your door and be quick when you midnight snack.

And one says, what about that other guy that hates burglars and has a burglar cage in his garage, we could ask him to get rid of the burglar?

No way, I don’t like his dog and he told us to not play our music so loud and he is boring to hang with.

Look, since the party is not gonna happen, best thing is to make the burglar arsonist our new roommate and try and ask him nicely not to start so many fires and try not to rape us. And another is like, hmmm, yeah maybe that is a good idea, we should all stick to our original plans because that is what we believe and all that matters! And shouts of

IGNORE THE BURGLAR!

IGNORE THE FIRE!

IGNORE RAPIST!

YAY HOORAY HOORAY HOORAY HOORAY HOORAY HOORAY HOORAY

PARTY PARTY PARTY PARTY PARTY!

And observing, as if locked in some insane mind bendy speechless nightmare of a tumbling vomit fest

Everything in my soul screams

CAN WE PLEASE JUST GET THE FUCKING BURGLAR OUT OF THE FUCKING GARAGE!

Little Waves

Hmmm, in pro audio we use wireless mics and belt packs for in-ears. Hand held and strapped these things to ourselves and our performers. Not long ago 600mhz band was sold off to the cell companies, kind of a huge bummer, and we had to buy and use new wireless gear in a different range. Pretty much 500mhz to 900mhz are frequencies that we audio humans use all the time, all good, no big deal.We also know that wireless mics and in-ears have drop outs if ya don’t get the antennas all set right and such.So answer me thisHow is it possible, even comprehendable that I am seeing pro sound people that strap or have strapped 500-900 MHz transmitters to their bodies and deploy wireless mics in the 500-900 MHz range, that see and are familiar with wireless gear, are getting mind bent about that same 600 MHz on a tower?WHAAAAT THE FUUUUCK?Come on sound humans, let’s leave that voodoo stuff to the people that want to freak out over 600mhz while holding a 850/900/1850/1900 MHz cell phone in their hand, right now as they read this before they hold the phone to their head for the phone call.So either take the angle of:OMG, there is a helical antenna on stage, we are all gonna die!OrYeah 5G? 600mhz? I know it and know it well, great frequency band till the damn cell companies hijacked it from us. We in pro audio deal with those same frequencies as 5G all the time, unwieldy and wow, I’d be quite the undertaking with lots of antennas to cover a city block, it’s tough just covering a stage without dropouts.The audio community even formed a coalition to try and keep the 5G frequencies, because we love them so much, but to no avail. Sad.And for all you non audio humans, here is a chart.

The Sound of Pause is Silence

Unlike pausing a video where the image lingers, or turning off the lights where all remains unseen but still touchable, pausing sound leaves us with silence. Unlike physical entities that can be examined and measured and then documented, drawn and shared with other physical entities, the measurements and of non visible, non feel-able, energies like sound proves defyingly challenging to represent using physical objects like paper and spec sheets.

Pondering this concept led me to decipher some test methods for hearing sound loss in speaker cables. I’ve recently started up doing some YouTube videos again and several that focus on these test methods.

Basically it is using a loudspeaker to directly listen to the losses in speaker cables and a second test unit that allows us to hear losses in mic and line level cables. The wiring is simple and easily something you can do at home with some bits of sound gear and a basic knowledge of wiring.

Here is a simplified schematic of the speaker cable test method

An amp drives signal down the input, through a speaker cable and there is a load on the other end. A loudspeaker, I use a home HiFi speaker, is connected such that one terminal is attached to the same wire cable we are testing at the amp end and load end. In effect, the cable we are testing is shorting directly across the speaker we are listening to. Any losses in the cable will manifest as audible sound from the speaker.

This test works surprisingly well and unlike a null test that requires one to tune the null, this outputs the speaker cable loss without any specialized gear or delicate tuning.

For more info and to hear results from various cables, check out my YouTube channel.

speaker cable test part 1

Cool cool and curious if anyone is still out there connected to this blog.

Dave

Perfecting Sound in the Wrong Environment

Ideas are magnetic and once a concept takes hold, minds and innovations seem to congregate, refine and push the limits, often to the point of absurdity. Or at least way past the point of diminishing returns. Meanwhile there are seemingly gaping holes between the popular concepts and those in dire need of resolution.

Take a moment and picture the scenario of setting up a table layout for a grand formal dinner with perfectly folded napkins, crystal champagne flutes, fine china and pristine cutlery placement. Confident with the presentation as guests begin to arrive you realize that mysteriously the table, upon which the masterpiece is set, begins to morph into something similar to a slightly undulating water bed. The exquisite meal now sits precariously balanced upon a liquid filled membrane as the stream of  guests obliviously lean against and push waves into rolling motion. Glasses toppling,  food sloshing and culinary chaos ensues. With a flurry of panic,  the staff reaches in all directions to regain control, sop up spills and replenish the losses. Just when it seems the entire meal will be hopelessly lost to calamity, the intensity begins to ebb, all that will spill or break, has already The messes become familiar, you’ve the replaced champagne flutes with more stable coffee cups on saucers. All excess frivolity has been carted away. A balance has been reached, tensions relax with a new and different result than the original intent but the wonderful food and smiles ramp up into a meal to remember with a rough start. The following day we begin our task again, we set this table carefully attending to each detail and once again the arriving guests are subjected to a chaotic start to an evening meal mess perched atop a rippling unstable surface. Over and over again each night the mystery repeats with us scrambling to resolve the issues as they arise. Until one day it dawns upon us and we realize the table has always been made of melting ice turning to various levels of slushy water each night sometime between preparation and meal time.

In this equation, we as sound engineers and system techs are the waiters setting the table, the band is the chef in the kitchen and the show audience is the dinner guests. Not unlike the sloshy water table party, we too as sound engineers, face the challenges of a changing and interactive environment. The venues we setup in may well be the same physical dimensions throughout the night but come showtime, the world we mix in often has significantly differing acoustic properties. My questions are: With so much precise analysis and prediction, why do we still enter showtime with so many loose ends unresolved? and Why do we not have an advanced set of tools to solve it?

I find tuning sound systems to be a real world example of what I wrote in the first paragraph regarding people clustering efforts in one direction while turning a blind eye to other critically important issues that dramatically effect the quality of the outcome. For example; it is not uncommon to spend surprising amount of time fine adjusting every single detail of time alignment, phase alignment and loudspeaker positioning resulting with complex EQ curves and extremely precisely calculated alignments. Then, after all of that time and energy spent on tuning, it is naturally tempting to have a  a vested interest in the correctness of those settings and to embrace an “I have this perfectly dialed in, don’t touch anything” mentality.

Meanwhile, many if not most situations wherein a sound system is setup, tested and tuned for sound check we find that the tonal balance and coverage of the sound system has significantly changed by show time. Perhaps we knowingly already made some predictive adjustments, perhaps we kept our settings from the previous night, to fall back on or maybe we just avoid soundcheck tuning altogether and use a previous gig file with some modifications for system configurations changes. Regardless, there is the clear and persistent disconnect between what we measure in an empty room and what we experience at show time.

Why? Why does the status quo of system tuning seem so relentlessly shortsighted? Is it ok to be repeating the same plan over and over again when nearly every time the results are flawed? Is the change in sound just some odd mystery that no one truly understands or is it just so unsolvable that we just ignore it and do a blind approximation after spending hours avoiding approximations?

Ah yes, its been repeated so many times it has actually become humorous. “Yeah yeah, it will sound better once the room is full” mocks the band back at me when I used to offer that as an explanation. Somehow as if we have the sound now and then we will have a different sound later and since we have no way of knowing what the other sound will be except different and most likely better but usually worse at first before we fix it.

Is it possible to bridge the gap? Is it possible to predict and compensate the difference between an empty and full room? Cold and warm room? Sunshine versus nightfall? I realize it may be a complex endeavor to predict the way an audience and environmental factors will alter the sound of a venue, but how complex? More complex that predicting the weather week in advance or designing a digital processor? We know where the people will be. It can not be that complex to calculate the approximate sound absorption of typical clothing and the sonic diffusive nature of a cluster of  human bodies. We know the average skin temperature and it would not be a stretch to calculate a thermal range for the amount of heat generated by dancing versus sitting. In most indoor venues we can have control over the room temperature and for outdoor venues, it is pretty easy to find out approximately what the air temperature will be. Is it truly out of our realm to continue the meticulous system tuning and carry it forward into the probable influences of the known factors?

One common issue I encounter involves flown clusters at outdoor festivals. Here are three scenarios:

  • The coverage area that the predictions software indicates based on the temperature used in the calculations
  • The actual coverage that occurs during the warm day wherein that heat from the ground refracts the sound upward and extends the coverage area, sometime hundreds of feet.
  • The coverage where the ground is colder than the air and shortens the coverage until the audience brings in their warm bodies creating a warm layer and extending the coverage.
As the coverage area is increased or decreased, there are also noticeable tonal changes that occur. The refractive changes caused by temperature are more prominent in high frequencies which means that as the coverage area is reduced, the sound in the coverage area gets brighter.
Ok so out of all of this, here are a few things:
  • The sound of a venue over time is dynamic and constantly changing due to numerous factors, I covered mainly thermal but wind, diffusion and absorption by humans as well as attenuation of frequencies over longer distances due to temperature/humidity.
  • Prediction software will not give you correct results if the real world environment is vastly different than the prediction environment. If the prediction is for 70F and the venue has 85F degree humans packed tight on a 60F degree night, the actual coverage will be way off.
  • It is important to properly tune and align a system, it is also important to be prepared for the inevitable changes that will occur when the people arrive and environment changes. Take note of the changes that occur and build a strategy for dealing with them into your system tuning plan.
Here are a few things that I do:

First of all, knowing that the venue sound is constantly changing I follow a “what EQ’s what” strategy. I use the channel EQ’s to make the mic/instrument combo sound correct.  I use the system processor  to fix any issues with the sound of the loudspeaker system design and array configuration issues. And I use a house EQ as a hands on control to deal with the constantly changing room sound.

For over a decade now I have been carrying an infrared thermometer which I use to measure room temperatures and work with the production manager and venue to try and create a consistent thermal environment.

I started using a Fluke Thermal Imaging Camera so I will be able to take more accurate readings.

I wrote an article called Thermodynamics of a Rock Show for Live Sound Magazine a while back which was nice to see recently re-released.

I posted  youtube video showing how a heatgun can demonstrate the refraction of sound away from the heat.

In the Youtube video I used a highly directional Parametric Speaker by SoundLazer which functioned well for the demonstration but I I felt the demo would be even more credible if I used a conventional sound source. So I did a short instagram video showing the heat from a stove burner altering the sound from a Jambox speaker.

Here is an article called Thermodynamics of a Rock Show for Live Sound Magazine a while back which was nice to see recently re-released.

Here a great article by Dennis A. Bohn from Rane Corporation:

Cool cool, as you can tell I am dwelling further into the heat aspects of sound for awhile.  Hopefully to find some ways to make things a bit more predictable.