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[E. Lee Dickinson]

Rob Spence wrote on Mon, 25 June 2007 23:51

I have one coming from the AMP shop on Wednesday with L14-30 in and out (30A 120/240v) and it cost me under $400.

For specific comparison.. my rack packs from Amp Shop have 50a twist In and Out, 6 20a circuits on the back, and a 20a convenience circuit on the front. Payed $320 for it.

[Rick Stansby]

Mark Hobbs wrote on Tue, 26 June 2007 04:08

My main problem here is connecting the main PD to a breaker box. Is this something that a skilled sound tech can do or is it a must to have an electrician on hand?

The answer is: "If you have to ask, then you need an electrician"

Quote:

If I can figure out the breaker box thing, pack racks + the wiring then my problem is solved. I can use all the amps and speakers planned (even the 1450s). I was quoted ~4 grand for rack packs (it sounded like he said 1 per amp, mabe I misunderstood him), main PD + cables. I hope he over quoted me becuase that seems steep...

You could easily spend a lot more than that on power distribution.  You don't need that much power.  As others have said: You would surely be fine with 1 rac-pac per amp rack, cabling and a few adaptors and tails.  You only need a PD if you have a bunch of rac-pacs. Since you have a relatively small system you could go from a 50A outlet (or a breaker) to the first rack and then daisy chain to the second rack.  When you can't get a 50A outlet you will have to unplug the amps from the rac-pac and plug them directly into extension cords.  If you aren't going into a lot of places with 50A/240V outlets, then you might be better with something like this: http://www.padrick.net/LiveSound/BarDistro/BarDistro.htm Which was posted by Tim Padrick who frequents this board.

If you go with the 50A/240 distro, be ready to spend $300 to get a 100 6/4 feeder cable with twist-lock ends, then another $600 on the rac-packs, then another couple hundred on tails and adapters.

[Tony "T" Tissot]

Ask the venue - and survey- "what power is available?"

No, you can't tie-in yourself. (The rule: if you ask if you can do it yourself - the answer is always no.)
Have an electrician mount a 50 amp receptacle wired for 240. He will protect the outlet with a 2P 50 amp breaker.

You could probably get away with 2 rac pacs with the 50amp connector (1 in - and one through).

($4000 is way too much, unless you are buying the complete 7 or 9 space metered 100 or 200 A rig.)

Just use the through connector to go from one rack to the other rack.

[Rick Stansby]

Mark Hobbs wrote on Tue, 26 June 2007 04:30

I have one 2 or 4 space rack (Road Ready) per amp...each amp has it's own rack/case. I dont have tall racks with multiple amps stacked up. It's easier for me to carry around individual amps then a single rack with multiple amps.

With a single rack for your FOH amps you will be able to save a lot of time wiring up the system each day.  You can build a panel with inputs for your xover, and outputs to your amps.  Then you can leave everything else hooked up all the time.  I think you will find that the time you save is worth the hassle of a larger rack.  Also the larger rack will have casters, so you won't have to carry the amps around at all.  I think you'll find a lot of people around here who do it this way.

[Mark Hobbs]

E. Lee Dickinson wrote on Mon, 25 June 2007 22:45

Then I would say, you should not be looking at rack packs. That said, I think you are right in line for a panel mounted to a hand truck, like I posted earlier, or a panel mounted in a road case, or any number of options for moving it around. Lowes and Home Depot sell books which'll show you how to wire up a panel, but you should probably have an electrician friend do it for you. Size your panel as you think you need. I think you could get away with a 50a panel, but if you really think you're going to load everything down heavily, you can build a 100a. Feeder cable will depend on if you go 50 or 100a. You're going to spend somewhere between $1.50 and $2.00 per foot for your feeder cable at 50a, at 100a you're probably looking at discreet cables.. hot, hot, neutral, ground. Tying in is not hard, but you need to be 100% confident that you understand everything you're seeing in front of you when you open a panel. That requires a good amount of education that you won't be getting on a web forum.

So, what you are saying is that EDUCATED sound techs commonly do this because they know what to look for, meaning that this is clearly not a *journeyman electricians only* kind of thing and thats what I am trying to get at. I am very aware that at the moment I am not qualified to tamper with live AC panels. But, with enough of the right kind of research and help (live help, not internet help) I could get it down. The guy I talked to at motion labs made it sound like no one on the planet with the exception of seasoned journeyman electricians would even consider attempting this kind of thing. I know I don't want to hire an electrician everytime I go to hook up a PA!!

[Elliot Thompson]

Mark Hobbs wrote on Tue, 26 June 2007 04:08

Elliot Thompson wrote on Mon, 25 June 2007 20:49 The QSC RMX 4050 is like my old EX 4000's in terms of power consumption. These amps don't pull a lot of current. You'll need to break down the power and, eliminate unnecessary amps. You can get rid of the RMX 1450s and strap the speakers that were on the 1450s to one side of the RMX 4050 being fed 8 ohms stereo. Split the signal using whatever you fed the 1450s, to one channel, and feed the other channel the same signal it was currently getting. Now the 4050 will be playing at 4 ohms stereo mode. That kills the 1450s. Two 1450's at 8 ohm bridged mono is equivalent to one channel of the 4050 in 4 ohms stereo mode in terms of output.   So, instead of 8 amplifiers, you’re down to 6 amps. You haven't loss any headroom and achieved lower power requirements. No matter how you look at it, you'll need a distro. Reason being, you are bridging four RMX 4050s. So, there’s really no way to get around that. You should have four 30-amp circuits for the RMX 4050s being used in 4 ohms bridged mono. The 4050 getting 4 ohms stereo will be fine on a 20-amp circuit and, the RMX 2450 getting 8 ohms stereo mode can sit on a 15 amp circuit. Possibly you can explain this to me. Why do you need to bridge your amplifiers if you are over powering speakers, and don't have the resources to feed the amplifiers correctly? It just sounds counter productive IMHO. You don’t sound as if you are volume 11 type of person. It may be best at times to just flip the switch back to stereo when doing venues that don’t require that much volume. When the need calls for more power, you just carry a distro to cover larger venues. Using two RMX 4050s in 2 ohms stereo mode will draw less current than four RMX 4050s in 4 ohms bridged mono. When the job doesn’t call for that much SPL, doing the above will prevent the whole distro scenario. Hope this helps! Best Regards, My reasoning behind bridging the 4050s? I have two 4 ohm loads presented that are rated for 2400 watts program and another two 4 ohm loads rated at 3600 watts program. I have 4050s to work with. The speakers are power hungry and I need spl. My choices are 2 4050s in 4 ohm stereo or 4 4050s in 4 ohm mono, so the mono option makes the most sense...or so it seems that way. My main problem here is connecting the main PD to a breaker box. Is this something that a skilled sound tech can do or is it a must to have an electrician on hand? If I can figure out the breaker box thing, pack racks + the wiring then my problem is solved. I can use all the amps and speakers planned (even the 1450s). I was quoted ~4 grand for rack packs (it sounded like he said 1 per amp, mabe I misunderstood him), main PD + cables. I hope he over quoted me becuase that seems steep...

I now understand where your weakest link lies. Thanks. I am in no way trying to steer you away from using all your amplifiers. I'm more or less explaining how to run your system with less power requirements when the need arise.

There are times, when we need to be more versatile with our systems. When the power requirements we get are not up to the task there are always alternatives, which is what my previous post was all about.

With Motion Labs, they are designing a distro that will be capable in delivering your amplifiers enough current at all times. Many soundmen compromise their distro due to not needing maximum current from their amplifiers at all times. So, it boils down to how hard you plan on driving your system, how long you plan on pushing those amplifiers, and how low of an impedance you're going to use.

By using four RMX 4050s in 4 ohm bridged mode, you are subjected in paying such a steep price due to requiring a lot of current. The best way to look at it is RAM usage in your computer. It varies pending on the user’s workload habits. Some users need 1 gig at all times where as others don’t need more than 256.

Your subs are your weakest link and, you are paying the price resorting to bridging four QSC 4050s. Many guys would’ve just bought two Crown I Tech 8000s, two Powersoft K 10s, or two Lab Gruppen FP 13000s because bridging four QSC 4050s requires a lot of current under a 120-volt line.

It's always safer to have some one qualified when piggy backing an external distro to a source. You could take a course or hire someone for those special jobs when the need calls for it.

If every event you do requires a distro, then it would be cheaper to know how to do it (Through schooling of course) than hiring some one for every gig.  

Best Regards,

[Rob Spence]

Mark Hobbs wrote on Tue, 26 June 2007 02:19

E. Lee Dickinson wrote on Mon, 25 June 2007 22:45 Then I would say, you should not be looking at rack packs. That said, I think you are right in line for a panel mounted to a hand truck, like I posted earlier, or a panel mounted in a road case, or any number of options for moving it around. Lowes and Home Depot sell books which'll show you how to wire up a panel, but you should probably have an electrician friend do it for you. Size your panel as you think you need. I think you could get away with a 50a panel, but if you really think you're going to load everything down heavily, you can build a 100a. Feeder cable will depend on if you go 50 or 100a. You're going to spend somewhere between $1.50 and $2.00 per foot for your feeder cable at 50a, at 100a you're probably looking at discreet cables.. hot, hot, neutral, ground. Tying in is not hard, but you need to be 100% confident that you understand everything you're seeing in front of you when you open a panel. That requires a good amount of education that you won't be getting on a web forum. So, what you are saying is that EDUCATED sound techs commonly do this because they know what to look for, meaning that this is clearly not a *journeyman electricians only* kind of thing and thats what I am trying to get at. I am very aware that at the moment I am not qualified to tamper with live AC panels. But, with enough of the right kind of research and help (live help, not internet help) I could get it down. The guy I talked to at motion labs made it sound like no one on the planet with the exception of seasoned journeyman electricians would even consider attempting this kind of thing. I know I don't want to hire an electrician everytime I go to hook up a PA!!

You will always get the "use an electrician" from any pro because
1) that is what the law says
2) if someone tells you to do it yourself and you or someone else get killed or the building burns down, there are liabilities involved.

So, no, you can't ask us how to tie in. If you have to ask, then you need an electrician.

[Bennett Prescott]

Mark Hobbs wrote on Mon, 25 June 2007 23:30

I have one 2 or 4 space rack (Road Ready) per amp...each amp has it's own rack/case. I dont have tall racks with multiple amps stacked up. It's easier for me to carry around individual amps then a single rack with multiple amps.

Mark, in all honesty, it sounds to me like you're taking a step up in system size and capability but still trying to get away with the old "just one tech, toss some stuff in a van and go!" mentality. Unfortunately, in the world of "real" production, that's simply not viable. Unless you want to stay in bottom feeder world competing solely on price forever (you don't) it's time to start re-thinking how your PA goes together. Rolling racks, quick disconnect power and signal, cable trunks, and careful labeling are a must have. You need to have a rig that ROLLS, that's labeled so you and a few other untrained idiots can get it in place (you make all the complicated connections, but they should be able to grab a rack and go stage left with it while you're setting up FOH), and that requires as little complicated inter-rack cabling as possible.

[Donnie Evans]

Mark Hobbs wrote on Mon, 25 June 2007 18:29

Amps: (4) QSC RMX 4050HD in 4 ohm mono   (1) QSC RMX 4050HD in 8 ohm stereo (2) QSC RMX 1450 in 8 ohm mono     (1) QSC RMX 2450 in 8 ohm stereo   About 19000 watts.

Exactly what cabinets are you planning to run with this much power?

If you don't wanna build your own... get one of these.

[edit]= added link

[James Duncan]

I hope I am not taking this thread too far off-topic...

The subject of electrical supply and routing is a tough one for us novices and bottom feeders that are trying to move up the food chain!

Those of you who have been around for a long time are familiar with some of these terms that just throw the rest of us out into left field without a glove. (OK, I will speak for myself, at least.)

"California connectors", "Hubbel Twist Lock" connectors, "Camlock connectors", "L14-30", "14-50P", "NEMA L21-30", single-phase vs. 3-phase"...

All of this terminology is way over most of our heads.

OK, sure, I can do a Google on any of these (which I have), but it gets really confusing, quickly.

Then there is the issue of 240v vs. 120v. All my amps are set to 120v, do I switch them to 240v, or does the distro take the 240v and split it into 2 x 120v?  How the heck can we mere novices expect to figure this stuff out?

I have built a "poor-man's distro" as outlined on this board with 3 separate circuits, but this is just a band-aid to really understanding how to get power to our systems as they grow in power and complexity.

It would be great if someone could write a basic primer on what all this stuff means, with pics of the different connectors and simple basic diagrams of how all this stuff if put together.

I understand the reticence in describing something that is possibly deadly, so leave that part out. Maybe start with what we might need at our end, and then what ends need to be present on the feeder cable that we can present to an electrician, etc.

If someone is willing to put something like this together, I would be eternally greatfull (OK, maybe not "eternally", but for a long time!!! ).

Lack of knowledge in my opinion is more dangerous than knowing about something and how it can hurt you. Leaving myself and others out to figure it out for ourselves can be more dangerous than giving us the details.