Step By Step: One Guy’s Path To Building A Pro Audio Rig
In perspective, it’s an efficient and cost-effective little rig, and one that packs in its entirety into my little 5 x 10 Wells Cargo trailer...

June 19, 2014, by Tim Weaver

live sound international

I’ve been in the pro audio business for 20 years, but I never set out to be a sound system provider. But in 2008, after eight years working at a large university’s theatre complex, well, as Bob Dylan said, “one day the ax just fell.”

I called all of my old friends but couldn’t find a decent gig anywhere. So I ended up mixing acoustic acts for next to nothing in a local bar and grill. This little bar had big plans, though. They started booking bigger and bigger bands to play on their patio, and the little speaker-on-a-stick system was not adequate.

The owner tasked me with renting enough gear to pull off bigger shows. It started with me renting the bar the small amount of equipment I owned – microphones, stands, and cabling. Next thing you know, I’m buying and then renting them a snake, some amplifiers and monitors, and a decent little income stream had developed.

But when summer turns to fall and then winter, as it is want to do, this outdoor patio-based bar overlooking a lake shuts down. Which effectively shut me down again as well.

Great – no gig (again), and a bigger pile of equipment. So I decided to make the plunge and went into business for myself. And I needed loudspeakers.

The Great Unknown
There were a few requirements that I set when shopping for PA. First, I needed to be able to stack it by myself. Keeping the weight low and the box size manageable was the top item on my priority list. It would do me no good to have a big impressive PA if I couldn’t load it in working solo. Next, it needed to be cheap. I was out of a job – enough said.

An Audio Centron triple-12 CE-36S subwoofer with a CE-17 top cabinet. (click to enlarge)

Finally, it needed to sound good (duh). But seriously, and more specifically, I wanted something that delivered solid, consistent horizontal coverage. Most systems are fine directly on axis, but the goal was to be able to move throughout the venue and have a minimal shift in response. In other words, array-ability.

There were very few options available in my price range that could be arrayed properly. I did run across several used sets of EAW KF360s, a great box which fit all of my criteria except one: price. However, it prompted me to check out 3-way designs, and one day while perusing eBay, I spotted loudspeakers with a name – Audio Centron – that I’d never heard.

Normally I would never suggest buying a system without actually listening to it. But I made an exception based on three factors:

1) The price was exceptionally low. (Do we have a theme here?) It was so low that I could part it out and sell the raw drivers for more money than I was going to pay.

2) I contacted Jerry Turnbow, who was director of engineering for St. Louis Music during the early to mid 1990s when these cabinets were designed and sold. Jerry was a terrific resource, providing original owners manuals, schematics, and general knowledge about the cabinets.

3) I found out that MB Music and Sound in Covington, IN, uses a lot of these cabinets, so I called Alan Lynch, the owner, and talked with him at length about their strengths and weaknesses.

Specifically, the loudspeakers are the CE Series, with the CE-36S subwoofer offering a triple 12-inch design, and the CE-17 top cabinets using a 12-inch low-mid driver, an 8-inch high-mid on a horn, and a 1-inch-exit driver on a horn. I bought four stacks of this combo.

All of the drivers are Eminence, meaning re-cone parts are easy to find, which was a good thing, because the PSD2002 compression drivers in all four cabinets were blown when I got them. (They’d been run hard, and then some, by the former owners.) However, once I replaced the driver diaphragms and a couple of resistors, they were in fine shape.

Little Jewels
The deal also included four monitors, Audio Centron CM-15s, which is a basic 15-inch, 2-way model. They weren’t really up to snuff, but there was a silver lining, in that they had Electro-Voice DH3 compression drivers, little jewels that can be found in some high-end loudspeakers, with an incredibly sweet and open sound.

Electro-Voice DH3 compression driver. (click to enlarge)

The DH3s were being crossed over too low in the monitors, leading to damage, but they would be fantastic in the mains – the CE-17 uses a very safe 3.9 kHz crossover point. The DH3 is more efficient than the PSD2002,  though, so I had to redesign the resistor network to compensate. It was worth it. These cabinets absolutely sing in the high frequencies.

With my mains sorted, I needed amplification, with the goal being to triamp the system. I already had a JBL DSC260 digital controller, so all that was needed was enough power, which I found on Craigslist. A wedding band that was upgrading to a powered system gave me a great deal on two Carver PT-1800s, two PT-2400s and two QSC PLX-1602s. All six were already mounted in two cases, along with some input/output panels and power.

The PT-2400s drive the subs, one sub per channel. The pair of PT-1800s run the tops in biamp mode, with one amp for the low mids and the other amp for the hi-mids and highs (passively crossed over in the cabinet) in stereo. I have exactly twice the RMS rating of the cabinets.

The PLX-1602’s deliver four monitor mixes. I racked these in an SKB 4U rolling rack, which allows me to have a pair of amps that I can grab any time for a small gig.

A quick word about those triple 12-inch-loaded subs. Wow, what a huge surprise. They get a lot of funny looks during load in, but that changes real quick when I start tuning the PA.

The subs have a quality to them that a lot of dual-18’s in this market can not touch. They are accurate, tight, and deep – the response extends powerfully down to the mid 30 Hz range. And they will get as loud as anything out there, and sound great doing it.

The Digital Route
A unique feature of my system is at front-of-house, where I’m using a Yamaha 01V96 console mounted in a mixer-top rack. I’ve been a fan of digital mixing for a long time, and first used a Yamaha Pro-Mix in the mid-90s.

My console is fitted with an MY8-AT card for an additional eight channels of ADAT in and out – a Focusrite Liquid Saffire 56 for channels 13 through 20, and a Behringer ADA8000 for channels 21 through 28. The ADA8000 is also handling all of the outputs from the console since it has XLR outputs, which are more convenient for me to use.

The slick front end of the system, with Yamaha 01V96 console and wireless tablet capability. (click to enlarge)

I’m able to send up to 16 ADAT channels to the Focusrite interface, plus the eight preamps that it has onboard, in addition to a stereo feed over S/PDIF in order to record – via FireWire – any live event. This gives me a maximum of 26 recordable tracks from a possible 32 console inputs.

The preamps are routed directly from its input to one of the ADAT outputs that feed into the console. I’m not monitoring anything from the computer, which means that for the live performance, latency never enters the equation, and I can run a comfortable amount of buffer while recording.

Untethered Mix
Another cool trick is that I built in is the ability to mix wirelessly. A Mac Mini installed in my rack is hooked up to a wireless router, and when I power up the front of house rack, it’s set to automatically boot up. The Mini also has Studio Manager and iTunes loaded in the startup folder. (If you’re not a Mac user, this folder is similar to the start-up items in Windows.)

The author mixing wirelessly. (click to enlarge)

A Lenovo X61 tablet computer is used to run RealVNC software that offers a remote desktop connection to the Mini. In tablet mode, the X61 uses a pen stylus, but you can also use your finger as an input device (although it is not multi-touch). Being able to use your finger is nice for some lighting programs that have a tablet mode.

The X61 has been a fantastic laptop for my production needs, and the wireless performance is great. I’m not using an external antenna, but I haven’t had any problems using the laptop from great distances and through walls.

Having the ability to mix wirelessly is a huge benefit. I can walk up to the stage and stand next to a musician while working on their monitor. I can walk to the front row and adjust fill loudspeakers. Or I can leave the entire front-of-house back stage and just walk out front with my tablet to mix. I’m hired for a lot of private parties and weddings, and not having to run a snake and take up a large area with electronics has been a huge hit with brides and party planners alike. In fact, I’ve gotten gigs for this reason alone.

Standard & Unusual
My mic complement is very traditional – Shure SM58s for vocals and SM57s for toms and most instruments, along with a pair of Sennheiser e609s for guitar, and an AKG D 112 for kick, as well as a Shure SM91. I also have a pair of Audio-Technica PRO 37s for condensers.

The oddball mics in my collection would be three Shure SM78s and an EV 635a and RE16. I like old mics, and I find that the SM78s sound fantastic on female vocalists and saxophones. They don’t have a transformer in them, so they have a more open and airy top end. (They’re not very monitor-friendly however.)

The RE16 works well for snare top. It has a great “pop” to it and sounds really beefy in the low mids, without being too muddy. The 635a is there because everyone needs an omni dynamic mic. I’ve tried it on all sorts of instruments and it always seems to make me smile.

To save some weight and space in my trailer, I’ve made it a point to use different ways to hold a mic without using a stand. I have LP claws, Shure A56D mounts, a Mic-Eze for the drums, and a few home-built Z-bars for guitar and bass cabinets.

I built a case that has an open top. One side of the case has eight holes that hold DR Pro tall tripod stands, while the other side is open and holds two Pelican 1500 cases – one for mics and the other for the aforementioned clamps, claws, Z-bars, clips, etc.

Shure SM78. (click to enlarge)

The rest of the gear is pretty standard, including Yamaha SM15IV monitors, chosen because they’re robust, loud, and priced right. The issue of poor off-axis response is not a big problem with floor monitors. The performers generally stand in one spot so you tune the wedge to sound good in that spot.

When I need it, a Peavey split snake with 36 channels and 12 returns can run a 200-foot trunk to front of house and a 50-foot trunk to monitors. It’s fully multi-pinned as well. The snake was acquired in trade for building an in-ear system for a band. I also have two 8-channel and three 4-channel sub-snakes of various lengths.

The stage box on the front end of the 36-channel snake. (click to enlarge)

The End Result
In perspective, it’s an efficient and cost-effective little rig, and one that packs in its entirety into my little 5 x 10 Wells Cargo trailer. It loads in and is ready for sound check within an hour, and loads out in about 45 minutes.

I can comfortably provide quality audio for crowds up to about 500 indoors, and have been in situations where 1,000 or so people have shown up and I got through the gig without damage (although I was pinned against the limiters all night). And, I can easily do multi-track recordings of any show.

The system in action at an event in Texas. (click to enlarge)

The system has been in constant operation for more than three years now, and I’ve only managed to burn up one of the 12-inch drivers in a main. (At an outdoor gig for a motorcycle rally.) Other than that it’s been flawless, even when I’ve really flogged it.

Tim Weaver is the owner of Weaver Imaging (www.weaverimaging.com), an audio, lighting, and projection provider based in College Station, TX. He has been a professional sound engineer for 20 years, working across all genres.



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Step By Step: One Guy’s Path To Building A Pro Audio Rig
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