# Portable "FOH" Rack



## sdauditorium (Oct 9, 2015)

I'm looking to create a portable FOH rack that could be utilized within the school district I'm the TD at. The purpose would be to support a variety of events in a variety of settings, such as sporting events in the main gym/field house, meetings in other spaces, potentially even outdoor events. Keep in mind, this is only processing/inputs. Then, the system could be easily connected to either already installed sound systems (such as in the main gym) OR plugged in to portable speakers which would be powered. 

Here's what I'm looking at including in the rack, but let me know if there's anything else that would be useful. Please remember, this is not including any speaker cabinets. 


Digital mixer - anywhere from 8-16 inputs that is rack mounted and could be controlled via app
EQ
2-3 Sennheiser wireless systems
CD player

Power Sequencer
The rack itself, obviously
With most people utilizing phones or iPads, I'm not sure if it even pays to put in a CD player, but it's probably a good stand by. I'd also likely have a panel-mounted insert with 1/8" jack for portable device playback. Is there anything I'm missing or would be a good addition?


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## jkowtko (Oct 9, 2015)

- The EQ will be included in the digital mixer ... Behringer X32rack should do you nicely.
- CD player ... what's that? Most digital mixers can do playback off of a USB flash drive, and if you use an Airport Express for wifi you can use Airplay ... but probably a good idea to have a CD player in there for the cases when someone hands you a CD at the last minute.
- wireless ... why not make it an even 4 channels ... two rack spaces with two units side by side in each.
- do you really need a power sequencer with this little equipment? Most of the time you won't be using the CD player, and will likely not use all of the pics all the time, so maybe easier to just have people power on what they need. I would add a power conditioner to the rack though.


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## DaveySimps (Oct 9, 2015)

I agree about not needing a seperate EQ and the power sequencer. Perhaps instead of the sequencer a power conditioner?

I always like having a 2 space rack drawer for securing mic transmitters, patch cables, extra batteries, tape, sharpies, etc. 

~Dave


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## Robert (Oct 9, 2015)

If you are powering your speakers from the rack then you might want the sequential power up, but you may not really need it and it's an expensive unit. I definitely would get a power conditioner with utility lights though. 

I have a Denon player that has CD/USB/Bluetooth capability along with FM tuner. In an educational facility you never know what people will show up with. As silly as it seems, I see cassette decks on occasion. 

I also have a pull out shelf that I find very handy when using another device such as I-phone or computer. 

I also have a wireless mic drawer. Has spaces for HH and lapel mics and belt packs as well as batteries.


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## tomthetechie (Oct 9, 2015)

The drawer will never cease to be handy. The X32 rack is great. The Soundcraft Ui16 is also a great option if you are looking to use an app for interface.


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## Footer (Oct 9, 2015)

Either go X32 Producer which will fit into the top of a rack or if you are into doing the iPad mix thing go with an X-AIR 18. And yes, you do need a CD player. Playback off of a USB drive is too difficult to always trust to be right. I have yet to meet a hardware playback machine that you can use to play stuff off a USB drive that is as cue-able as a good CD player.

One of these...
http://www.sweetwater.com/store/detail/X32Producer

With this....
http://www.sweetwater.com/store/detail/MP103USB

and this... 
http://www.sweetwater.com/store/detail/PL8C

and this...
http://www.sweetwater.com/store/detail/EW135G3-A

and these...
http://www.sweetwater.com/store/detail/DRWDF3

and one of these...
http://www.sweetwater.com/store/detail/GigRig1406

Personally I'm not a fan of the all in one racks. I would rather have a console and a small processing rack all on a table and run a hose between the two. To each their own though.


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## themuzicman (Oct 9, 2015)

sdauditorium said:


> Digital mixer - anywhere from 8-16 inputs that is rack mounted and could be controlled via app
> EQ
> 2-3 Sennheiser wireless systems
> CD player
> ...





I would ditch the outboard EQ, bump up the wireless to 2x Dual Channel Receivers, and throw out the Power Sequencers. In a few hundred pro theater installs I have never once had a use for a power sequencer. If you are worried about blowing your circuit breaker at "burst" on powerup, I would get an American DJ PC-100A as your "fake" power sequencer. Otherwise, just get a few rackmounted power strips. 

I would add to this a battery backup. 

Instead of the EQ an outboard DSP may be worthwhile if you have a bunch of fixed systems you will be tying in to, you can save all of their preferences in the DSP and then change over as needed through the memory. This way your bus structure in the desk can stay static between that and the outputs. I would also get a bunch of either punch out panels or Middle Atlantic panels and create custom rack rails on the outside so you are never mucking about with interconnecting wires on the inside of the rack. Label the thing up really nice and call it a show.


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## AlexDonkle (Oct 10, 2015)

As others have said, you can likely leave off the outboard EQ, CD player, and Power Sequencer (a rack mounted surge protector alone is likely fine). I would rack mount a Mac Mini w/ LCD monitor on an arm + keyboard. Connect this to the audio console via USB, and you can pre-load audio tracks on iTunes, Qlab, etc. Alternatively you can get a rolling rack with space for a laptop to be set down, but make sure the USB jack on the audio console is easy to access. 

Rack mountable consoles other than the X32 Producer already mentioned include Allen & Heath QU-16, Soundcraft Expression, and Yamaha TF.


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## JohnD (Oct 10, 2015)

I betcha that Fullcompass might make you a better deal, just tell them you don't really want to deal with that "S-word" company.
That SKB case is certainly "interesting". Personally, I like the classic road case style cases. Take a look at Audiopile.net
http://www.audiopile.net/C12U-P
That's the basic model, and for not much more money there is the unit where the front and back covers become tables, might be very useful in some situations.
http://www.audiopile.net/CUDJ-P
They also have great prices on drawers, mic cases and mic stand cases. Shipping would be high but they are very good at palletizing and shipping LTL freight.


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## Footer (Oct 11, 2015)

JohnD said:


> I betcha that Fullcompass might make you a better deal, just tell them you don't really want to deal with that "S-word" company.
> That SKB case is certainly "interesting". Personally, I like the classic road case style cases. Take a look at Audiopile.net
> http://www.audiopile.net/C12U-P
> That's the basic model, and for not much more money there is the unit where the front and back covers become tables, might be very useful in some situations.
> ...


I don't buy from either of those companies ever... Good for reference though. Only issue with those cases is the x32 needs a 14 space rack and that's hard to find in this format.


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## FMEng (Oct 11, 2015)

The X32 family has a couple of limitations in playing audio files from a USB stick:
1. It plays only wav files, no MP3 or other format.
2. The file sample rate has to match the console's internal sample rate. The console runs at 44.1 or 48 kHz.
3. There is no time readout.


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## MikeJ (Oct 11, 2015)

JohnD said:


> I betcha that Fullcompass might make you a better deal, just tell them you don't really want to deal with that "S-word" company.
> That SKB case is certainly "interesting". Personally, I like the classic road case style cases. Take a look at Audiopile.net
> http://www.audiopile.net/C12U-P
> That's the basic model, and for not much more money there is the unit where the front and back covers become tables, might be very useful in some situations.
> ...


These are actually pretty good cases for the price, and a good working height while standing or sitting in a stool. Way better than the SKB.


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## AlexDavila (Oct 12, 2015)

I don't think it's been mentioned, but you're also going to need a wireless access point if you plan on operating your console wirelessly from an app.


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## TCJ (Oct 13, 2015)

Just my 2 cents worth, if you want to save a few cents worth:

I wouldn't bother with the power sequencer. Just have your technicians manually sequence the start-up and shut-down.

On systems I've set up requiring specific sequences, I've placed small label tapes on each "critical" device beside the power buttons, with 2 lines of text such as:
*ON: 1st
OFF: 4th*​
System operators then only need to follow the trail of label tapes (in their enumerated sequence), as indicated on either their first line or second line of text, depending if they're starting-up or shutting-down.

It's cheap. It's one less device in the rack. And it subliminally teaches operators the audio signal chain, and which devices produce start-up or shut-down "thumps", and which devices have huge inrush currents. (Or it at least gets some of them to ponder the rationale behind the sequence and then eventually figure it out.)


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## derekleffew (Oct 13, 2015)

I think that's a great solution to a (non-existant, IMO) problem @TCJ. As long as the power amplifier(s) (not included in an FOH rack) are the Last ON and First OFF, what difference does it make in which order processing/drive/console are powered?

So @sdauditorium, as everyone else has said, skip the Power Sequencer, and replace it with a power conditioner (and even that is questionable), but every rack wants minimally a Furman PL-8 just for the rack lights and power strip.


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## DuckJordan (Oct 13, 2015)

On the subject of power order, I have yet to see any issues with flipping power off in any situation. Sure you hear a pop once in a while, but flipping the board off before the amplifiers, or the processor before amps. I've yet to see problems in 8 years of working in this industry.


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## Footer (Oct 13, 2015)

DuckJordan said:


> On the subject of power order, I have yet to see any issues with flipping power off in any situation. Sure you hear a pop once in a while, but flipping the board off before the amplifiers, or the processor before amps. I've yet to see problems in 8 years of working in this industry.



Really? I have... plenty of time. Mostly in the form of blown cones.


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## DuckJordan (Oct 13, 2015)

Not a single blown cone or welded driver. This has been true for EV x array and Martin W8s

Sent from my XT1060 using Tapatalk


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## Footer (Oct 13, 2015)

DuckJordan said:


> Not a single blown cone or welded driver. This has been true for EV x array and Martin W8s
> 
> Sent from my XT1060 using Tapatalk



How is your head then? Because usually after I hear that noise I want to take a bat to the head of whoever caused it.


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## DuckJordan (Oct 13, 2015)

I'm just the lighting guy my boss is the audio guy so I've never done it myself

Sent from my XT1060 using Tapatalk


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## GreyWyvern (Oct 13, 2015)

Footer said:


> How is your head then? Because usually after I hear that noise I want to take a bat to the head of whoever caused it.


@DuckJordan is magical afterall. Remember, he can touch lamps with his bare hands too!


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## DuckJordan (Oct 13, 2015)

GreyWyvern said:


> @DuckJordan is magical afterall. Remember, he can touch lamps with his bare hands too!


I'm starting to wonder, if I just have exceptions to the rule all the time....

Sent from my XT1060 using Tapatalk


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## TCJ (Oct 13, 2015)

I've heard speaker coils (well, technically, the cylinder on which the coil is wound) knock against the back of the magnet, from improper shut-down and start-up sequencing. The "thud" (usually) doesn't totally destroy the speaker right away, but it does cause the cylinder end to flare out / deform a little each time. Eventually the deformed cylinder starts to scrape the magnet and the speaker sounds like scratchy crap. (At that point, it's destroyed.)

I've also come across speakers where the glue holding the coil cylinder to the cone has cracked. These too sound like crap and need immediate repair, before the cylinder becomes completely detached from the cone. (I can only imagine such damage occurred from the momentum of a sudden and very loud transient... such as the "pop" or "thud" that some equipment emits upon start-up and shut-down... and likely slammed the cylinder into the magnet.)

I've also seen people rip off their headphones and rub their ears in pain, while shouting every swear word in modern English vernacular... and of other languages too... because of a loud switch-on / switch-off "pop" somewhere up the signal chain. (I've even done this myself -- guilty as charged.)

And of course, crowds don't usually take well to something that sounds like a surprise gunshot in auditoriums with very powerful PA systems.


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## FMEng (Oct 13, 2015)

A sequencer won't prevent pops unless both FOH and amp racks are controlled by it. In the OP's situation, it won't so he might as well not waste money.


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## DuckJordan (Oct 14, 2015)

I'm not saying you should make a habbit of turning off the amplifiers last. I just doubt the "facts" about the damage...


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## GreyWyvern (Oct 14, 2015)

DuckJordan said:


> I'm not saying you should make a habbit of turning off the amplifiers last. I just doubt the "facts" about the damage...


Really?! Seriously man, just stop. With both this and the lamp thing. There is plenty of evidence that touching lamps can shorten their life and "pops" as a result of incorrect power up/down sequence can damage speakers. That is why the manufacturers warn you about those things. Does it happen everytime? No. That doesn't mean it doesn't happen at all though. Just because you may not have been paying enough attention to lamp life or know when a speaker may have needed repair (since you are lighting and not sound), doesn't mean you and those around you are the "exception to the rule." There is another word for people like you and it isn't lucky. Just the _fact_ that the manufacturers have warnings about these things is proof enough that they do happen. They are actually trying to save you time, trouble, and money. That's what was so funny about what @DELO72 said. Relamping/avoiding fingerprints on Lamps
It is stupid to argue just for the sake of arguing, which you are doing. Stop. Please.


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## Dionysus (Oct 14, 2015)

Indeed, it is rather rare for power off/on to damage speakers, but it DOES HAPPEN. I have seen it. Its rare but why not power off/on in the correct sequence and eliminate the chance for said damage? Its such a simple thing to do that reduces chance for damage and such.

Putting a single bullet in a revolver and pointing it at your head will 1/6 or 1/8 (depending on the revolver) of the time, so would you argue that playing russian roulette will never kill you because you've done it twice and did not die?


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## MNicolai (Oct 14, 2015)

FWIW, in a properly installed and tuned system with responsible gain structure and limiters, it's not as easy to blow a speaker up. Digital consoles have also gone a long way to reducing the amount of power-up pop. Sound systems aren't exactly the wild west they used to be in terms of things you need to know to not blow them up.

But, alas -- there are a great number of people who do not understand gain structures and like to use their amplifier's gain knob as a general purpose volume knob or more egregiously leave the amplifier's gain setting wide open. When that happens and someone sends a pop through the system (especially when the DSP is lacking appropriate limiters or there is no DSP), they send a much higher intensity signal out to the loudspeakers.

Another factor at play is when the correct crossovers, high-pass, and low-pass filters have not been used for each speaker type. Sending a pop to a speaker at the frequencies it's designed to handle is bad. Sending a full-range pop to speakers elements unprotected from the frequencies above or below their rated frequency handling is worse.

You would be surprised how many installations I encounter where:
1) The gain structure where the amplifiers are set wide-open and it's up to the person at the console to keep all fo the inputs gained way down.
2) None of the loudspeaker manufacturer's specified filter settings are included in the DSP.
3) The HF signal is routed to the LF and vise versa.
4) The DSP is used as a matrix router and has minimal or no system tuning whatsoever.


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## AsherSB (Oct 14, 2015)

Back to the rack- The QSC TouchMix provides hardware to mix with, but has a built in access point for app based control. It doesn't come cheap at $900 or so for the touchmix-8 but about the same price as a wireless mixing system, a router, and an iPad. Unless you already have a Sennheiser system I would opt Shure instead, really anything will work as long as it's UHF and a known brand. Audio technica's system 10 also looks nice, but I don't have any experience with it. I agree with whats been said about the EQ and power sequencer, both expensive and unnecessary. Other then those I would go with @Footer's recommendations, but maybe a smaller case and drawer.


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## sdauditorium (Oct 26, 2015)

Thanks for the help. We're working on quotes for the back-end of the system (installed, distributed system in the gym as well as proper processing, amps, etc.). The reason I'd prefer Sennheiser is for consistency. Our auditorium and football field all utilize Sennheiser (22 wireless in all), and my experiences have been great thus far in nearly 15 years. It's nice to be able to swap out handhelds or body packs without worrying between venues. The TouchMix was sort of the leading contender and had been on my radar, so it's good to see that mentioned.


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## MikeJ (Nov 5, 2015)

@MNicolai, you need to google gain structure, then re-read your last post.


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## MNicolai (Nov 5, 2015)

If you're referring to my remark about amp gains being left wide open, that's because wide open means different things to different manufacturers. Gains on the amps should be consistent with attenuation for artistic blending defined in the DSP, but the gains for the amps should be based on feeding a sine wave into the amp and measuring the output with an oscilloscope, not by just setting the amps wide open and relying on each manufacturer to engineer their product with perfect precision.

I'm not up to speed on the exact levels and voltages we look for when we do this because I'm not the guy in our shop in charge of that process, but whenever we get a new rack built up in our shop, we hook it up to 8ohm loads, burn the amplifiers in, and monitor the waveforms with oscilloscopes for abnormalities. Aside from making certain the gains are dead-on, it stress tests the amplifiers to make sure they won't fail prematurely.

Manufacturers are inconsistent between models and other manufacturers, and sometimes even between copies of the same model. Just setting the gains wide open doesn't do what you'd think it would.

The side issue to this being that when the gains are thrown wide open without being tested and measured, we oft see there are other issues in the gain structure that result in someone barely lighting up the meters on the console when the system is freakishly loud. That's more a reflection of the installers overall approach to gain structure though than of the effect that just incorrect amp gains have.


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## TCJ (Nov 6, 2015)

Well I guess everyone has their own style. My typical modus operandi:

1. Play a sample song or other "test signal", similar to the typical programme material, through the main mixer.
2. Set the main mixer's faders to 0 dB.
3. Raise the input channel gains until the output VU meters mostly stay at or slightly below 0dB.
4. Set the FOH EQ/FX rack's "programme EQ" trims to 0 dB.
5. Raise the power amplifier gain controls until the sound level is at the loudest you anticipate you will need it for the upcoming show.

For non-permanent systems that always have their controls tweaked and re-tweaked and bumped around between installations anyways, I find this works well.

There's no need to consult data sheets or product manuals for all your audio sources, be they +4 dBu or or -10 dBV, or something else, or a consumertrash gadget's headphone jack that could be pretty much anything.
Your faders pretty much always end up landing in a nice range; never maxing out, and never being too loud while still at the bottom end.
Should you misjudge the amplifier gain setting and your master fader is stupidly high or low, you can always tweak the FOH rack's trim.
Should anything ever go wrong in _ANY_ of the upstream equipment or its connections, causing a "pop" in the audio signal... the amplifier gains are _NOT_ "wide open", therefore the resulting "bang" in the speakers won't be as traumatic.
Hiss and noise is kept to a minimum -- Everything upstream of the amplifiers is being operated at levels that achieve best SNR.

I tend to facepalm when I see techs twist the amplifier knobs all the way clockwise as one of the first steps, before even running the first sound check signals through the system.


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## TimmyP1955 (Nov 15, 2015)

Yes to a CD player, preferably one that will read discs of MP3 and MP4 files as well as standard audio CDs. Then hope that it will read the home-burned CDs that you are handed (I once had a disc that neither my CD player nor my WinXP machine would play.

You don't need a power conditioner, just a good power strip. Though for digital widgets, a UPS would be nice. At my day job we use these:

http://www.provantage.com/tripp-lite-smart3000net~7TRPM002.htm

http://www.newegg.com/Product/Product.aspx?Item=N82E16842106109


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## TimmyP1955 (Nov 15, 2015)

Amps wide open is the safest way to go. If you set your limiters with your amps wide open, no one can render your limiters useless by turning the amps up beyond where you had them.


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## len (Nov 15, 2015)

I'm no audio guy, but I do pay attention to what they do. With the changes in technology, there's always something new, so I would not get married to any one product. All the stuff that you find you're not using any longer (old cd players, etc.) can be put into a secondary rack that you can patch in or something. A rack with a top mixer is the way I would go, but what you put into it is going to be up to you.


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## TCJ (Nov 28, 2015)

TimmyP1955 said:


> Amps wide open is the safest way to go. If you set your limiters with your amps wide open, no one can render your limiters useless by turning the amps up beyond where you had them.



That's only if your "limiter" is a device permanently bolted into the power amplifier rack, and permanently connected to the amplifiers... and locked out from tampering.

But if the cables being plugged into your power amplifier line inputs are disconnected & reconnected for every new show setup, that theory goes out the window.

And if the limiter settings are _not_ locked, someone could just as easily change your limiter settings as they could hypothetically change the power amplifier gain settings. Therefore you're not really protecting anything.

That's only if your "limiter" is


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## brin831 (Dec 5, 2015)

Ui16 console ... works with any device android or ios ... 10 users at the same time ... also has included wifi access ... also includes usb for recording or playback of .mp3.wav etc. 

Im usually in the get 4 wireless mic if you are getting three also check out the ulx-d quad 

As for a rack skb gator etc but get one with a caster board !! Rule 1 if it's not on wheels it doesn't go.


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## AsherSB (Dec 5, 2015)

No matter how nice the Ui16 may be, I would be nervous without a physical control surface. The ULX-D systems are great, just expensive, and maybe overkill in this sort of situation.


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