Dave Rat - Roadies in the Midst - Vortex/Orgasmatron and Slotfire Sub Setups

Fast, Loud and in Control

nospam@example.com (Dave Rat) — Tue, 29 Sep 2009 21:06:35 -0400

The Scooter

Check this sexy machine out! My favorite tour necessity.

As innocent as it looks, this baby cruises at 17 miles per hour has two 21 cell, 25 volt 5000 mAh NiMh battery packs hidden in the belly, each good for 10 miles on flat ground and the brushless motor offers almost zero rolling resistance, folds up and weighs in a mere 28 pounds! The Xootr EX3. Heck, back before 9/11 I used to ride to the airport from old house and carry it and a backpack on the plane for short trips. Unfortunately I am sad to say these are long discontinued. But if you ever can get your hands on one, you will not regret it.

Like everything though, things break. Especially if they are my things.

The most recent repair was a battery issue where a connection between calls broke. It's a bit of a pain to fix but at $175 bucks a pack, it is well worth the effort. By poking small holes in the shrink wrap I located where the bad connection was. Then cut away the shrink and carefully bend out the cell. The issue is trying to resolder the cell back in without dissembling the whole pack. But, since NiMh cells use the outer can as the negative, there is a workaround. If you solder a thin metal tab to the positive of the cell in the pack then slide the cell you bent out, back place:

You can cut away the shrink wrap and solder the tab to the outside of the can. It is a bit hard to see but if you look carefully, its there.

And back on track! And hey, look what I found!

An honor indeed! Thank you Travis, Mark and Tom for inviting me on this incredible adventure.

My Office!

Ok and on to:

**** Sound Nerd Speak ****

Ok, so one of the wonderful realities of our world as traveling sound humans is that everyday is a new adventure. So now that the Vortex (Orgasmatrons), Slotfire and V-Fire setups are running smooth and predictable, we can now start upping the anti a bit. We learned from Jones Beach shows that the Diagonal Vortex was effective for venues that require a narrower coverage. Remember that Vortex was designed to cover up to 135 degrees off axis but in a field or shed that is too wide. So rotating them 45 degrees does well for narrower coverage patterns.

But as anyone who has toured knows, we have to deal with a wide variety of setup spaces, restrictions and issues. So here are a few more setup variations for y'all to ponder.

Vortex two dimensional control. Offers rejection behind the subs and on stage. Needs space around them. Offers very wide coverage. Steerable. Occupies an 8 by 8 footprint.

Slotfire single dimension control. Coverage is symmetrical in front and behind. Works best when against a wall to block rear energy. Steerable width. Offers rejection center stage and somewhat behind. Controllable front compression alters sub tuning/tonality. Requires 13 by 4 footprint.

V-Fire single dimension control. Coverage is focused forward and reduced behind. Does nor require a rear wall. Steerable width. Offers rejection center stage and somewhat behind. The V is less than optimum and slightly downgrades the tonality. Requires 13 by 4 footprint.

But what to do in this venue in Birmingham? We had a fairly open space. The barrier to the right in the photo is audience side and just a blow through scrim. Unfortunately there was not enough room for a vortex without jamming up monitor world . Plus the vortex would have to be diagonal to be aimed right and there was no way. So here is a Smooshed Vortex setup.

The math works well and coverage should be good with excellent rejection behind and on stage. But wait? Really? Am I going to point a 3 stack of double 18"s at our monitor guy?

Well, it made me nervous enough that we setup one side with the middle speakers pointing toward the audience but the math was not a good.

and the other side as the calculations told me would be superior

And we fired it up and sure enough, we spun the other side and ran with double 18"s pointed right at a happy Steve!

And how about one more setup that may com in handy and is super easy. This is basically the setup we used at coachella and works on the same principle as the Slotfire

Two stacks of 6 subs per side. Space at 8.5 feet center to center. Lay in a 3ms delay to the outside stacks and bingo. Simple clean 180 degree 45 hz-ish center frequency cancellation towards center stage and focal points like 20 or 30 degrees off center. Longer delay widens and shorter will narrow. Though the side effect of other delay times is that your cancellation area moves around.

**** End Sound Nerd Speak ****

Two of these belong to me!

And off to watch Fall Out Boy!

Dave Rat

Just Because I Can

nospam@example.com (Dave Rat) — Tue, 08 Sep 2009 13:42:46 -0400

Each trade has tool set. The fundamental and most basic item around which that craft is formed. A carpenter's hammer, a logger's ax, a fisherman's rod. The older the craft the more archaic the tools tend to be.

For a chef, it is the knife, Here our head caterer Jeremy's love for these handmade Japanese folded steel knives is so deep it literally brings him to tears as explains their quality and craftsmanship

Speaking of crafts and using tools, here you can see the proper usage of an XL4 as an elevation platform while foot mixing.

Missy is our tour manager Adam's assistant and doing a fine job of making that Rat hoodie look awesome.

Ok, you are at a gig, option 1, head to your seat and watch the show, Option 2 hop into kiddie pool fully clothed with some dudes. Hmmm, tough tough decision.

Fortunately though, someone from the radio station that came up with this brilliant idea relieved us of this unsightly obstacle soon after the show ended buy dumping a torrential waterfall down the seats creating a 3" deep lake for the subs to sit in and the crew to saturate their shoes in during load out.

Check out this mirrored drum head!

**** Sound Nerd Speak ****

Ok, link of the day comes from my good friend Jamie Anderson who heads up Rational Acoustics. While I roll with my basakwards low tech and analog ways, Jamie does Smaart training and is all up on the other approach. So when he stumbled upon this gem, he knew where to send it. The ultimate analog delay!

http://www.uaudio.com/webzine/2005/august/text/content4.html

And on to less serious stuff. When I was laying out the initial Vortex designs, I started with what seemed a good place. Take the B sub and place in a conventional manner, then build from there. I really try to break down those barriers and open up to all possibilities but looking back I realize that it had no real logic other than just clinging to something familiar. And that decision made without fully justifying meant that the design was a bit less optimized than it could be.

Below you can see a simplified drawing of what is going on with the summations and cancellations of the Vortex setup. On the left side you see a counterclockwise setup on stage left. On the right side you see a counterclockwise setup stage right. Though the setups are the same, notice how much cleaner the left side is.

Green arrows represent summation, Red represents useful cancellations in the band that we are reproducing and gray is imperfect summation with some cancellation. The arrows are drawn from box center through box center. The arrow lengths are meaningless.

One of the issues we had with the original setup was that I was getting a bit too much sub off to the sides. So I started pondering and realized, hey wait, let's reverse directions of the Vortex and it should move our primary focus to the deep corners of the arena where we want it and paper and sure enough, the real world result matched the pen and paper prediction!

**** End Sound Nerd Speak ****

Ha, meet Juan (lampi), Robert Rat (stage), Josh (carpenter), Jim Rat (foh), Derek (automation - stuff that moves during the show, like Travis), Randy (Famous Stars and Straps promo), Jeremy (food), Me (trouble coordinator), and Justin (automation)

And so ends another terrible day at the office.

Dave Rat

Doing It Wrong

nospam@example.com (Dave Rat) — Sun, 06 Sep 2009 21:24:16 -0400

**** Sound Nerd Speak ****

I have had quite a few people ask me "how did you come up with the sub layouts?" So, I started thinking about the train of thoughts that is passing by here at the moment. My first experimentation into 'subs pointed the wrong way,' was the Sub Cannon stuff I did with Peppers.

Thought actually they were pointed in the right direction, the setup had one set firing into the back of the next time delayed set. While it worked well, and rear rejection was clearly achieved, cumbersome steering that was realized by adding more or less level to them, so power was wasted if I reduced side coverage. But way before that, all the work I was doing with the MicroWedge designs over a decade ago kept pointing at the assets of physical placements and the importance of versatility. Physical placements, distances and the reducing the sheer physical size of the combined sound sources continue to be a significant challenge in all loudspeaker enclosure/array designs.

For this year's Coachella we did something very similar to the Slotfire setup where it relies on two sub sources 1/3 of a wavelength spaced. But once all the subs were stacked up, what we ended up with is a big wall of subs with a small gap in the middle separating the non delayed versus the delayed. Some delayed 18's were right next to non delayed 18's while others were 12 or more feet away.

Yet we are using a time delay of just 3 ms. The theoretical design is based on two point sources but the whole sub wall thing, while functional, has trouble getting out of it's own way. What we need is two nice clean point sources. But how do you do that with six double 18 boxes that are nearly two feet high and four feet wide?

From yet another angle there was the MicroSub project designed to use the coolness of actually being able to physically configure the boxes themselves to achieve desired results.

http://www.eaw.com/info/EAW/Loudspeaker_Product_Info/Current_Loudspeakers/MW_Info/MicroSub_Configs.pdf

Yes subs are very close to omni directional at low low frequencies and since low frequency wave lengths are long, it may seem that these configuration variations would have little or no effect on the output and coverage. But the reality is that there are significant audible differences and once I actually stacked these things up I found the assets of the configurations are even more pronounced than anticipated. The actual direction a sub is pointing does not matter much till you start getting above 60 0r 80 hz. While the 'on axis' focal point and distance between multiple sub sources rapidly gains importance as the frequency is raised.

**** Mini Offshoot Sound Nerd Speak ****

For example. The MicroSubs are 26" wide and 13" high and hold a single 15" speaker. If you stack two directly on top of each other on the floor like 'The Up Up' configuration,

the source dimensions are about 26" high by 15" wide plus ports so about 26"x24".

That would give us a side view pattern of something like:

As you can see we have we have reduced the vertical coverage, which optimizes for musicians a bit farther away and blows through the legs of closer artists when used as a sidefill.

Now slide the top MicroSub back till it drops into the 'Laid Back' configuration

and we now get something more like this

Where there is an up tilt giving us a nearer focus. Here the nearer artist is in the focus while the sound will tend to go over the heads of musicians father away. Plus, this is with just two MicroSubs. The stacked responses are of course achievable with conventional low profile subs but the additional option to utilize the angled configs with the MicroSubs is unique and can be very effective in tackling a wide variety of applications.

**** End Mini Offshoot Sound Nerd Speak ****

Ok, back to Vortex and Slotfire.

So taking what I learned from Sub Cannon's, MicroWedge, MicroSub lets next add in add in the cool enclosure designs like the dV-Sub http://www.l-acoustics.com/fichestech/dvsubgb.pdf where multiple speakers are pointed at each other to result in a powerful output from a small area.

And then it grew on me to combine it all and gain control over steering by creating a smaller and more manageable sound source dimensions and completely disregard the direction the sub speakers actually point. At that point all the ideas started flooding in as with so many restraints of design removed.

Here is the Slotfire, notice the two 18" wide 'slot' sources that offer distinct control.

And though the Vortex occupies an 8 ft by 8 ft by 5.5 ft high space, it offers a relatively small point source-ish output relative to conventional setups.

Oh, and this was the gig where we learned that the Vortex works best in open space and does not like to be near a wall. The Slotfires though, prefer a wall and shoot too much rear energy in open space. The V Fire:

is the no wall or hollow stage version of the Slotfire but does not quite sound as good.

**** End Sound Nerd Speak ****

So as I mentioned, I adore the new adventure feeling of opening the bus door to a brand new world. And some days you just got to grit your teeth and bear it. Dammit, where in the heck is the parking lot? Is that a gig through yonder forest?

The luxuries for a touring roadie crew are endless, but at least we get our own are to hang out in and relax.

I did it, I finally broke down and labeled my console.

So this Branson guy from Virgin decides to toss a party for 30,000 or so of he best friends, for free. Multiple stages, Blink, Weezer, Jet and lots of other cool bands

And what better way to make an entrance than to sky dive out of a helicopter onto the roof of the main stage at Blossom Amphitheater? None better! A bottle of Champagne

And away we rock. Can I say that this guy rules! And speaking of guys that rule, I am so happy to be touring once again with Craig Overbay! So great to hang with so many friends.

Dave Rat

The Melt Down

nospam@example.com (Dave Rat) — Sun, 23 Aug 2009 18:43:53 -0400

Any of y'all who have followed my bloggery adventures for a while and I have not bored away, you may recall my FOH techs Nick the Fly and Happi-Lee. Nick started Peppers with me and I like to have out during the design phase early on. Then Lee joined on with his amazing and precise skill set that really locked the PA into an amazing level of consistency. For this Blink tour, Nick once again got me started up but I could not get Lee. Instead I have the fabulous honor to be working with none other than Jim Lockyer, new tour nickname yet to be determined.

I can not stress enough the importance of having a high quality PA tech. Especially for my spacey forgetful self. I heavily rely on my techs for consistency and attention detail as I want to walk into a setup as close to identical as humanly possible everyday. My goal is to purely focus on any venue to venue issue but the system and everything else must be in its proper place.

Now typically I am a calm and easy going individual but when there are issues that involve gross negligence, or complete disregard, I can really ramp up into a frenzy that I highly recommend everyone avoid. So imagine my surprise when I arrived at the sound board to fired up the system and noticed this

I know, it is hard to look at and sorry for putting you through it, but it was too big of an issue to let slide. Yes, the zig zaggy pad edge is missing its outer strip. Frozen in time I felt a full melt down rush over me. JIM, what the fuck kind of ship are you running here? I thought you were pro! You came highly recommended. Sigh, I thought you were my friend :(

Not only was the strip not in its proper position, it was actually sitting on the console for the last few shows. But since I mix in the dark and rarely look there, I had not noticed.

How am I supposed to mix the god damn show if I am limited in my padded roaming room? Can I mix like that? No I can't, no wonder the last two shows sucked ass. This absolutely unacceptable! Aaaargh! I am out of here. I can not work under these conditions but fortunately our head of tour security, Tony the Tiger, captured me as I was running off and convinced me to give Jim another chance.

He assured me it wont happen again and that he will do all posssible to be spot on from now on.. I was relieved to see his dedication renewed and I snapped this photo of Jim tuning the sound system the following day, notice the RTA mic with the orange spiral tape.

Here we can see Jim line checking:

So, far since "The Pad Event" he has held things together very well. Lets just hope that he keeps his wits about and priorities straight. And in case he forgets:

#1) No Lights! No board lights, no rack lights and computer screens must be facing away from me or off during the show.

#2) Carpet and pad setup properly.

#3) Wine glass never empty and make sure I drink plenty of water.

#4) The mixing Stick must be readily accessible at all times.

#5) Make sure most of the PA works and sounds halfway decent most of the time.

For those of you unfamiliar with the mixing stick:

Ok, now that I got that off my chest, enough with the serious stuff.

Hey, can you guess where in the truck the KUDO boxes were after the rainy gig?

I really am enjoying this tour and I really feel loved

And it's is fun! Ha!

**** Sound Nerd Speak ****

Finally, as a side note, Notice the modified Slotfire setup we are calling V Fire?

Basically, same theory as Slotfire, but closing the backs up puts a lot less sound under hollow stages. Slotfire does sound a bit better and offers a smaller point source as the V opening needs to be larger to work properly. But, sealing up the back really help. So wall or solid behind, we use Slot, Hollow or open behind, we use V. We even used a combo wit on slot and one V per side when the inside stacks were in front of the hollow stage and the outsides were against concrete.

**** End Sound Nerd Speak ****

Next up, well dunno yet but it will be some ramblings about something or other.

Dave Rat

Big Tools

nospam@example.com (Dave Rat) — Tue, 11 Aug 2009 22:55:11 -0400

Jones Beach. I remember the first time I ever did a show here was Lollapalooza 1992, the first of two shows went on with out a hitch but for the second show our little friend Hurricane Andrew decided to drop by for a visit and lay a category 5 wind and rainstorm on top of all the wires, speakers, lights and humans. Talk about torrential downpour! I have some old video of it somewhere that have been meaning to post. Pretty intense seeing the lights and PA swinging and mashing into each other. Big chunks of gear blowing over into foot deep puddles flowing in a cascading waterfall off the stage while sideways rain blows away tents and any attempt to protect the not so thirsty gear.

So I have settled into two subwoofer designs and hope to be able to flow one or the other into the rest of the tour gigs. The Vortex or Orgasmatron setup gives me a bit more control over coverage and allows me to disperse low end over a very wide area. Also the Vortex gives me excellent rejection on stage and directly behind the subs. Our other setup which I guess I will call the Slotfire Cannon. It is similar to the Sub Cannons I used to fire to the sides of the arena's on Peppers tour but they take up less depth, are more efficient and offer a bit better control. Being four feet deep and about 14 feet wide, the Slotfire should be able to drop into most sheds fairly easily. The has quite good control over widening coverage but offers very little cancellation behind the arrays. So for venues that have a wall behind the subs, the Slotfire is a good way to go. Conversely the Vortex work best if there is open space behind them.

Perhaps you noticed we spun the Vortex (Orgasmatrons) 45 degrees? Ahh for this gig it gave us better sighlines, so therfore better placement downstage and a bit more control. So here is the basics of the Slotfire setup as done morning of the show;

The theory on the Slotfire is to space two acoustic centers at 1/3 of a wavelength of the desired center frequency. For this I chose 45hz due to the sub design and program material I am sending, so about 8.5 feet or so. Then if I delay the outside acoustic source by 3.6 to 7.2, I gain a tremendous amount of control to steer the low end to the outside. Zero time delay gives me a figure 8 pattern, which I do not need as I want to steer outward and reduce power alley. Here are some simple predictions for one side

A 3.6 ms delay is 1/6 wavelength at 45 hz so if you apply that to the outside subs and add that to the 1/3 wavelength physical spacing, we get that 1/2 wavelength virtual spacing that gives nice cancellation towards the stage and steers low frequencies outward

And as we increase delay further it steers more outward.

So super simply I can control how wide the coverage is while reducing power alley, just by adding delay.

The trick though to get this all to work efficiently is to create two nice LF point sources with the subs. Ahhh, and that is where the super cool part comes. Because to get an 8.5 spacing of acoustic centers with 4 foot wide boxes means the stacks would only be 6" apart. Basically one big wall with some time delay mushing it up, which is lame and boooring! So what I did was to point the subs at each other with 12" spacing. Now I have two very clean 12" wide acoustic centers to work with. And wow! This setup kicks butt!

The sound of this setup is really solid and powerful, more so than the Vortex. But, keep in mind, the Vortex offers more control. If I setup the Slotfire in an arena, poor Steve and everyone else behind the subs would be completely obliterated. Never forget that the key is using the right tool for the right job.

Haa! I got to be the guinea pig for the flying drum riser test drive!

I think this was Montreal

May as well start introducing the awesome Rat crew out here putting up with my antics. Meet Jim, also known as Ice, not sure why but hey, nicknames rule. He is my FOH tech and the one who directly gets my world dialed in. I do put a lot responsibility on my tech, and really appreciate him keeping it together. Oh, Nick the Fly was out here but he went back to home world and was the front end guy that helped me get my wacky designs all dialed in.

This is Robert, he rocks the stage wire world

Scott Sugden (top left) came out for a few days to hang with us and Roz (working with Scott) is our laser room measuring K1 system design guru now that Nick is gone.

Manny is out here too promoting corn chips mainly but I think he does some PA setting up as well.

Re ran the orgasmatrons at Jones Beach. Good news is Mark Hoppus went inside during the show. Bad news is he tripped over the strap that holds them together and fell inside with his bass on mid show. Fortunately he did the party roll and landed on his back and seemed ok.

Hello Me

Jessica is our wonderful production assist and awesome to work with.

May as well toss some show shots in the mix

After the gig, we Blink fans all hang out waiting for the band.

Not really related but some say Pigeons are like flying rats, so I figured I would toss some props out to our flighty friend here.

Okey dokey artichokey. See ya soon for more brain twisting adventures soon.

Dave Rat

Nothing is Perfect

nospam@example.com (Dave Rat) — Thu, 06 Aug 2009 19:36:38 -0400

Comcast Center, formally Tweeter Center, formally Great Woods in Boston but actually is 25 miles away from Boston in Mansfield Mass.

The thin crust of an eggshell that had formed around my nearly two years at home has been sufficiently shattered for me to begin to see tour world clearly. You would think that well over two decades since my first tour, I would have a nice warm familiar groove to settle into. Hey, isn't touring like riding a bike? Once you do it, you know forever. Perhaps, but with so many complexities and patterns I have carved into over the years, which one will I be? As I re-enter tour life, which of my past tour patterns will envelop me and which pattern do I strive to embrace? Regardless of my intentions though, the unique dynamics of each band, travel rhythm, fellow crew friends and my life stability levels all whirl-spin together and at some point I find out where I land. It at that point which I can truly decide which direction to head.

And here I am starting with two extremes and working my way to the middle. Deep dives into technical ponderings in between reckless indulgence in the freedom from the mundane responsible of the everyday land locked life I lived just few weeks ago, all magnified by the gaping holes left where the things I miss reside.

Finishing up the design phase of adapting the sound system to sheds and finding a stable tour pattern. Must drink less because if I continue at this lushy pace I will start losing everything thing, like cameras, friends or my own humanly self. Oh, and also I need to work on finding this tour's hobby or adventure. Speaking of tour hobby, this is the exact venue that donated the seat to the electric go-cart I made on the 2003 Peppers tour!

http://www.ratsound.com/cblog/archives/177-Day-221-Dec-30-Home.html

And so, nothing truly is perfect but some things are way better than others and now that we have the sub Vortex system all dialed in, at least we are done doing arenas so I get to start all over. Would not want to get bored and running with 'typical' is soooo booooring.. Lets take a dive into the pleasure of coming up with a brand new shed design. Fortunately, the design of the various amphitheaters (sheds) varies so drastically, that nailing down a repeatable setup is going to be a challenge indeed. My strategy is to come up with three setups to select from and pick the optimum for each venue. The Vortex is choice #1 and surprisingly we were able to run with it in Milwaukee

How well do the Vortex actually work? On the down side, when you light up an entire arena with low end and really cover the sides well, the sound of the subs is naturally going to be a more 'roomy' over all sound. But that is a price I have to pay for getting a more consistent sub sound in the room.

Also, we are doing really well at getting a smooth sub level in front of the stage, but at the diagonals where the sub Vortex stacks are focused toward the deep part of the arena, there is substantial output, especially during the drum solo. So the sub output is hotter than I would like in those areas. That said, it is much more consist ant than any other ground stacked sub setups I have used. Oh, plus they look cool and I can alter the coverage a bit with delay times and levels.

One of the goals with the sub setup was to be able 'fill and not kill.' As in fill the arena and not kill Steve, Doug, Robert and Chris, the backline techs. Steve Walsh drives at the other end of the audio snake during the show and literally five feet away from the back of the subs. Chris is even closer. I will rock some pics of all the tour humans at some point but first I have to remember all the names.

Anyway, take a peak at the alternate shed setup

And the design notes:

And no matter how large you roll, someone somewhere just has to one up ya!

Dave Rat

Going Deeper

nospam@example.com (Dave Rat) — Thu, 30 Jul 2009 04:25:47 -0400

Sitting at out first real show with full production after doing the listen wanders. All American Rejects were on stage and I had my first chance to get a solid idea of how the Sub Vortex system is working. Yes, Scott, Vortex is winning like 30 to zero so far. Whatever. Anyway, we are pretty happy with the setup. The diagonal fire focus is really effective but a bit too wide of an angle. Rear and stage side cancellation is substantial. I am going to do one change next show and run them the opposite directions as I am calculating much better aim and focusing deeper to the rear of the venue. The time alignment comes up much cleaner with B and C being identical in delay and D at about double.

Plus the cancellation s are better aimed to the side and rear and it eliminates the D to B cancellation aimed into the audience center. I realize that for you tech head types, my drawings are probably shockingly over simplified and lack all the fancy colors and such, but hey, this is how I figure the stuff out, so I am sharing the raw methods.

Here are the actual shortest distances from acoustic center to acoustic center. Though in reality some of the path lengths are altered by the cabinets being in the way.

Grabbing the two approximate primary distances of 3.6 feet and 6 feet and taking a look at the effect on cancellations we should see behing and stage side of the array

We can see excellent rejection in the 50 to 70 range for our B to A and C to A combos (50 is mid way between green and yellow but not shown). For our 6 foot DC and DA combos we see the polars below which offer more control to a lower frequency. The DB polars at 4 feet read somewhere in between these.

All in all we are seeing a good amount of cancellation and due to the various combos, it should be a well spread attenuation rather than concentrated in a narrow frequency range.

The Listening System

Moving on, check this out! We have four pairs of wireless transmitters/receivers with high quality omni lavaliere mics attached. These Sennheiser units are the same systems that video cameras use for wireless audio on transmission/reception and the receivers are the same units that are used for in ear systems. And while I am at it, and for some shameless self promotion, if you need any Sennheiser or any audio gear for that matter, give Daniella a shout at the Rat office and she will hook you up with great deal. Ha, tell her you are a friend of Dave Rat!

And Nick the Fly with the mics and transmitters.

We can place these at various locations in the venue. Though the mics are not perfectly flat in response, they are close. Since the data I am looking for is simple frequency response, we have the four mics and a hardwired RTA mic all run into console channels. We have calibrated by placing them next to each other and set gains so they all read the same sensitivity. So now I can PFL any of the mics and see the response of that mic on the RTA. I do not really care if the read out is flat, what matters is that the mics give me an RTA reading that looks like RTA reading from the reference mic at FOH mix position.

So now, very simply I can see on the RTA and hear in my headphones various locations during setup and sound check and we don't have to run a bunch of stupid mic cables all over the place. So far we have not built housings for the transmitter so that they can live in the audience during the show, but we are pondering a method.

These reference mics give us the power to quickly figure out if the sub Vortex system is working as desired, are totally wireless and easily transmit the distances we are dealing with.

Oh, and just for the heck of it, here is a link to the SB28 owners manual.

http://www.l-acoustics.com/manuels/SB28_UM_ML_1.0.pdf

**** End Sound Nerd Speak ****

Hmmm, did I mention that the drum riser flies? And spins, and tilts and Travis rocks the house in a huge way. Really cool to see and I get to push those subs right on up to vision blur mode! Check out this sexy setup!

And to further soften the landing from all the heady sound nerd world, this is my shorty Sammy

This here would be my other shorty, Maddie and the cookie we made. Why make a bunch of little ones when you can make one huge one. Go big!

And hey, there Taco!

Nick the fly, me and hey, my dad, say hello papa Rat!

My friend for over 35 years, say hey to Brian Rat who started the company with me. We did a bit of surfing at San Onofre before I left.

Don't mess with Taco! He is my guard blog.

Next up, lasers and perhaps a new name suggestion has been put forward for the Vortex. This one may be a hard one to beat!

Dave Rat

A Sunny Day Off in Vancouver

nospam@example.com (Dave Rat) — Mon, 27 Jul 2009 23:41:11 -0400

It is quite a drive from Vegas to Vancouver so I stayed an extra day in Vegas got a bit of work done and a bit of fun done before jumping onto the bus adventure. All good, 3 hour flight lands 30 minutes early, we taxi up to the gate, well, not quite the gate. We can see the gate but pilot informs us that there is a bit of a lightening storm. While the storm poses no threat to us plane people, the airport has decided that the humans that normally cruise around in those squished looking airport vehicles should stay indoors till the storm passes. I woke up two hours later pulling into the gate. A quick dash down to customs and oh my. They have unloaded the entire airport backed up constipation of humans all at once onto a meager smattering of customs agents working overtime. I felt quite at home as it looked like the floor of a small but packed arena with the only exception being that my backstage pass is useless here. Zig zag lines that would give Disneyland a run for its money on a weekend. So funny to keep passing the same people, back and forth we go till at last, with a few too many questions and a stamp in my passport I am on my way.

Ooooh. Yikes, look at that taxi line. Double yikes as the 1/2 block long clusterfucks is aimed straight at a 2 little Prius Taxi's and every few minutes another zips in. "Is that really the taxi line?" "Nope, that is the the taxi line" Pointing to another 1/2 block line twice as thick that wraps around the other side of the road. "This is the front half."

Five motionless minutes spent at the tail end convinced me to seek a better path. Free hotel shuttles looked hopeful only for me to discover that they drag you to Airport hotels and I'm headed downtown.

Aaargh and then I see it. A small sign. "Public Transportation." A bit of a hike, a bit of a wait and on I hop. "I am sorry sir" eyeing my $20 canadian bill, "We only take change on the bus." But before I had a chance to ponder my next move, he goes on to hand me a bus pass, wave me on board and gesture to the next person in line to get on."

Welcome to Canada and I smile as not fighting the things beyond my control brought me in for a smooth landing. A very very slow, but smooth landing.

I must remember to have one of the hotel housekeepers teach me how to make a bed. How do they do it? It would take me half the day to get a bed to look like this! There must be some secret tricks or something.

Ok, back to **** sound nerd speak **** lest I get distracted, not that that ever happens.

Subs. So after all the various configuration were sifted, I narrowed to three with a distinct focus on one design that seemed most promising.

First though a bit about distance and subs. There is a magic distance when spacing subs for maximum forward summation and maximum rear rejection of 1/4 wavelength of the frequency that you want the most rejection to occur. The reason is that if you space them one behind the other 1/4 wavelength in distance and then time delay the front 1/4 wavelength, then in front they add together with minimal loss while behind they are effectively distanced at 1/2 wavelength. Since 1/2 wavelength is 180 degree out of phase, you get maximum cancellation at that frequency.

Which frequency you design for depends on your subs and other factors but typically 40 to 60 hz is pretty good. 1/4 wavelength of 50 hz is about 5.5 feet and a good place to start. That means that a five foot spacing from center of sub to center of sub, with the subs being around 4 feet wide, is about a 9.5 foot width with not much gap between them. The good news is that it is close to the size I am seeking for this design to fit under an 8 x 8 deck.

So far I do all my designs on paper with computer assistance only for drawings, based primarily on logic and experience and I do the math by mostly by hand. But hey, I mix on an analog console as well. But that does not mean I can not use computers to check my work, so I sent it off to Sugden to run some projections and see if I am on base and have taken all the variables into account.

The Spiral or as Scott Sugden came up with, The Vortex are the names I am considering. Have you noticed yet that I like to name things? A bit of fun and makes it easy. How about a vote? Spiral or Vortex?

Anyway, here is how it is supposed to work. There are four stacks of three SB 28's with two stacks facing forward (toward mix) and two stacks facing to the side (off stage).

Sub "A" stack is the primary drive on each side with stack "B" time delayed to increase level forward and cancel level behind. Stack "C" is time delayed "A" as well to increase level to the side and cause cancellation on stage. Stack "D" is time delayed to increase level at 45 degrees while canceling at 235 degrees.

All in all the primary array focus is 45 degrees and by increasing or reducing the level of stack C and some altering of delay times, the coverage can be narrower or wider. The interaction between "D" and "B" also adds somewhat at 200 degrees and cancels at towards stage. The "D" to "C" interaction is forward beneficial as well as "D" has the longest delay time.

The end result I want is a well diffused power alley, significant power to the deep diagonal throws of the arena, controllable side coverage, excellent rejection on stage and minimal overpowering of the people in front of the stage.

I know from experience that having two point sources for subs will cause some issues and I will get cancellations just to the sides of where power alley usually is. But, this should setup should be much better behaved due to the effective focus 45 degrees off axis. The combined response looks a bit like a butterfly.

To deal with gaining more control over power alley and help diffuse the cancellations off to the left and right of center, we are carrying 4 stacks of two Rat Super subs evenly placed across the front of stage. The time delay on these will be focused on FOH and the level can be varied to optimize.

To make these things easy to setup, Nick the Fly designed some inserts that our tour set carpenter made for us:

Fitted inside the wood aligners allow us to easily repeat the setup. Another wonderful aspect about this sub setup is the creation of a special little hang out spot for the sound techs in case they want to just get away from it all for a bit of relaxation, as Manny is demonstrating.

Having these ideas and projects is all good and fun but actually making them work properly is and testing how well they work is another challenge. So now it all about brainstorms and unraveling the fact from fiction with Nick the Fly. Nick and I have toured quite a bit together in the past and has been extremely involved and familiar with the progress of these concepts into reality over the years. Did you know Nick actually was the cabinet builder for many Rat designed boxes. I would send actual napkin sketches and he would build stunning enclosures.

As I mentioned, I personally am not so much a pretty picture kind of guy that keeps messing with software to try and find a coverage that looks good. Rather, I try and solve from a logical approach, try to confirm with the software and then do actual testing. Then, if logic, testing and software all agree, I gain confidence.

So to address the measurement side I have finally put together something Nick the Fly and I have been discussing doing for years now. How cool would it be to have a simple system where we could drop reference mics in various locations around the venue to monitor the sound without running a mile of mic cord everyday. A system that does not rely on trusting whether you are getting a correct reading from some super high tech measurement software. But rather a quick look and listen in real time.

Well, I will describe that some other day.

**** End Sound Nerd Speak ****

So if that was not enough thinking for you, I have a bit more. Jim, Nick the Fly and I were out for a wander and happened upon my very first Canadian yard sale. Hey look, speakers! I love speakers and upon closer inspection I began to poder a question and have a little test for you.

Ok, so there are these speakers in your car and you think to yourself, "hmmm, I want to take these speakers out and put in new ones." Now for the big question. Which tool do you grab out of the tool box?

A) The screwdriver with a square drive and loosen the screws

B) The 3/8" socket wrench and loosen the nuts on the back and remove the nuts

C) The oxyacetylene cutting torch and shoot flames into the inside of your gas powered vehicle

If you guessed "C" you are absolutely correct! For the rest of you, come on, think first before you do things.

Dave Rat

More Homework

nospam@example.com (Dave Rat) — Sun, 26 Jul 2009 14:39:43 -0400

More Homework

So just as I did for the Coachella sub setup, I set a few goals and restrictions to see where that would take me with the design. And just as I did with Coachella, I have the honor of being able to run the designs by Scott Sugden from L'Acoustics who has the skills, experience and software to sort through the options. I really do feel fortunate to be able to not only try and figure out cool solutions but also to have the support people and sharp humans that can help me implement these things on a fairly large scale.

Lets start off by clarifying a simple rule of thumb regarding configuring speakers.

The wider you stack speakers horizontally, the narrower the coverage is horizontally. The higher you stack speakers vertically, the narrower the coverage is vertically. This is counter intuitive at first as it is tempting to stack speakers wider and wider to cover a wide room. When using horns and with mid and higher frequencies that can be easily controlled in their directivity, stacking wider for wider coverage can work well. But the rule of thumb is based on multiple speakers reproducing the same signal with their coverage patterns overlapping.

With sub woofers, overlapping coverage patterns are all but unavoidable, so the rule of thumb works well, especially with larger arrays.

OK, so the premises I am following are:

1) Horizontal sub arrays reduce horizontal coverage and create a power alley in the room center reducing coverage to the sides. - I need to keep the sub arrays compact horizontally.

2) Vertical sub arrays tend to reduce vertical coverage. A flown vertical sub array further messes up vertical coverage due to the reflection effect. I will try to keep the subs on the ground.

3) A stacked vertical sub array is a bit more forgiving in its vertical coverage than a flown array. Yet more concerning is that the tall ground stack in an arena will usually block sight lines unless it is behind the band, and we surely do not want the band in front of the low end I am going to dumping on the audience. Keep the sub array compact vertically.

4) A stage center horizontally ground stacked sub array blasts the front row of humans and tends to arch over backwards onto the band. Even with a cardioid sub array placed stage center, my experience is that, having the singer just a few feet from the primary subs generating enough lows for an arena creates an inevitable mess. Avoid putting lots of subs stage center.

5) The setup must be easy, repeatable and be able to cover the venues without the time consuming tedium of meddling with multiple interacting delay times every day. I want two or three clean presets that I select from. Maybe a 180 degree coverage, a 220 degree and a 270 degree. Create a sub setup that allows changing coverage without re stacking.

6) Finally, as with any useful idea, the less negative side effects, the better. So the sub array ideally should not reduce venue capacity, block sight lines, push out the barricade, look ugly, or cause any issues for backline, lights, video or any other department. Plus it would be really cool if it was easy and fast to setup.

Hmmm, that really tilts toward putting subs on the floor and off to the sides as the best of the options without diving into an some esoteric 3 dimensional flown sub arrangement that would change the rules a bit. In order to reduce the power alley effect, creating a sub woofer setup where each side has a bit of reduced coverage in the room center should help.

Anyway, based on those parameters and keeping in mind the quality of the overall show as whole, the most finessefull solution seemed to be to refine the sub cannon design for added control and improved coverage. Reducing the quantity of forward facing subs towards the stage middle would be good as well.

Here is the Peppers sub configuration drawing for the 2006 -2007 tour

And a picture of it

I will also need to account for the fact that I will be using the L'Acoustics SB28's rather than the Rat subs I had on Peppers tour. I love the Rat subs and with the new Rat Super Sub, the added power is awesome. But Rat Sound has the privilege of being one of only two vendors with a K1 system in North America during this pilot phase of the K1 system release so both Rat and L'Acoustics really are focused on keeping it all intact as a complete system so we can really learn the rig and share what we experience with the manufacturer. That is not to say that it can not be augmented, but for the primary system it is all about a matched L'Acoustics rig.

So I am going to walk the line between off the shelf L'Acoustics with a bit of optimization based on my past experience and setups.

Picture time. This is pretty much the way I start projects. First establish a rough goal based on fulfilling the need or solving a flaw to what is existing. Next start drawing pictures and try and cover all possible permutations regardless of whether they are feasible or not. I then sort through the pictures and weed out the weak ones, hopefully settling in on a small range while weighing the assets and issues. Finally refine, redraw, build and test the winners out.

Just to give you an idea of some of a few of the 20 or so layouts I went through, here are some really rough stage right sketch's that did not make the cut for this tour.

The Fan. This would have the rear three at zero time and a delay added to the front three. I never ran projections as it was too big for what I am working on here.

The Focus. With all the work on the design of the EAW MicroSub, I have been diving into and using mechanical coupling arrangements, this is a triple sub setup seemed interesting. The delayed center can be timed to steer the coverage a bit. Never tested it and it seemed to be too limited in control.

Two behind three. This is a 12 x 12 foot and cumbersome. But perhaps you can see where I am headed with attempting to have control over the forward fire, diagonal fire and side fire while offering some cancellation on the stage and behind the subs where the monitor position and techs will be.

The Quad. The size is getting better and with subs pointing forward and to the right combined with delays it could offer some control. I really want power delivered about 45 degrees to the right of center. That tends to be the longest shot in an arena as well as a place where people will not be really be too close to the subs due to sight lines.

The Circle. Similar, and though you often hear that subs are omni directional, it does not take a rocket scientist to walk around the back of a subwoofer and hear that they are a bit louder and more direct sounding in front. This sub circle could have all subs facing inward or in several differing directions.

The Split. The next one actually is pretty good and fits in an 8 by 8 foot area. I could time delay it it for a 0 degree, 45 degree or 90 degree focal point. A bit light though, I was hoping to get 12 SB28's per side and to match the stage height so I am looking at 3 per stack. Meaning this is a 9 sub array. The sub on the right would add power to the side while offering some cancellation on stage. The sub up top in the drawing adds power forward and cancellation behind. the interaction between the top and right subs should cause some cancellations to the upper left power alley area and lower right 135 degree off axis area. By messing with levels a bit, the coverage could be altered a bit. Plus the distances are hovering around that magic 1/4 wavelength of 60 hz range which is useful for cardioid sub configurations.

Oh, and let me not forget the most important part. The Carpet.

How can we possibly do a rock show without a nice fuzzy carpet to stand on!

Next up, more subwoofery stuff, some simple cool measurement tools and running it old school style.

Dave Rat

Figuring and Flying

nospam@example.com (Dave Rat) — Sat, 25 Jul 2009 22:17:14 -0400

Here we go Blink 182 and cool rock show. I have not really figured out my direction yet as far as blogging and adventures but in the mean time, I may as well rock on the tech side of things. Will work on losing my mind later.

The Los Angeles Forum was the playground for testing and getting things dialed in.

So what is new for this tour? Well, the new K1 rig is a monster! Truly some breathtaking horsepower, V-Dosc with nitro boost. Aside from the significant jump in clarity, it can pump enough low end from the main hangs to make the subs almost optional.

Similar to the Peppers rig, I am once again using an 8 foot by 8 foot sub array with a blow through aluminum grate on top that doubles as stage wings. It is a really cool way to go as it gives me a lot of freedom with the sub design without eating up valuable floor space while keeping the setup clean visually. My goal once again is to attack the issue of whimpy low end off to the sides of stage and while gaining control over how much power alley there is.

For those non-soundy humans, power alley is the term used to describe the area down the center of the venue where the low end tends to be more powerful than elsewhere. So in itself I guess a 'power alley' is good for the humans hanging out there but that also means that everywhere else is not a power alley. For some odd reason, it has become a commonly accepted practice to have a strong power alley. Personally, though I love the low end power, I really work hard to get the sound as consistent as possible throughout the venue. Forget power alley, I want a Power Valley and I want everyone in it!

Easier said than done. Turns out that if you stack horizontal sub arrays on the left and right sides of the stage, they will be loudest midway between them while off to either side of center the low end drops off quickly. One solution is to put all the subs in the middle which works fairly well and also tends to completely wipe out the band on stage with low end. Also, the center sub thing tends to really smear the heads off the humans parked in the front rows.

Another method that is becoming more common is to fly vertical line arrays of subs. This solves the blasting the front row humans issue quite well, offers improved low end off to the sides and a more reasonable power alley. The issues are that the vertical sub line arrays create these cancellation nodes that project like spokes just to the left and right of audience center. The cancellation nodes can be quite pronounced to the point where there are areas with almost no sub right next to areas with powerful sub sound. Another drawback with flown subs is that they create a sideways power alley. By that I mean that there is a power alley effect that offers strong low end at floor level that tapers off as you increase in altitude. You see, the floor acts like a mirror to subwoofers. When you stack subs on the ground, the subs are sitting on the mirror, in effect doubling the energy radiated.

Just as power alley occurs in the horizontal plane (wide vertical, narrow horizontal) with subs stacked side by side on either side of the stage, a vertical power alley is created when subs are flown in a vertical line (narrow vertically, wider horizontal) caused by the interaction between the flown sub array its reflection in the mirror (floor). Since power alley is in effect most pronounced for the locations horizontally equidistant from the subs, with a flown sub line array, the subs are loudest for humans vertically equidistant from the subs and their reflection. In other words, there are challenges in the vertical coverage with the center of power alley at your feet dropping with elevation. For a flat field show this is not really an issue, and can be an asset but in arenas and venues with humans up high, the reduced vertical coverage can be a significant issue.

Several years back I was doing a show where the sound vendor swore up and down that we needed to fly subs. Even after I killed the idea, I was surprised to not only find that they were flying subs when I arrived, but they went on to tell me they were going to fly twice as many. Why? Well, they went on to explain that they were having trouble getting low end into the balcony area of this huge indoor sports venue. After a bit muscle flexing and much to their dismay, I pressed the issue, made them drop all the subs and we ground stacked. I then personally walked the balcony with the head sound tech during the support act. "Better?" I asked. He was quite surprised and fully agreed that the subs to the upper sections issue was solved. The price? Well, I had power alley back in the horizontal again which meant the lows dropped to the sides. But for that venue which was not very wide, the percentage of people that heard solid low end was significantly increased.

Alright, time to fly, more to come tomorrow as I try and regain some bloggery momentum.

Dave Rat