Speakers for auditorium sound?

Among my graphic art jobs for them, I also help with set construction for a theatre. While working on the set we often plug my iPod into the theatre sound board. We use the mini jack to left/right RCA jack cable to patch in. Sounds fantastic coming out of those big speakers.

I would think you'd need a bit more power than that. You did say it was for 400 people in a room with rather bad acoustics? I would think you'd need an amplifier and beefier speakers than the desktop models otherwise you'll bust the speakers and they still won't sound loud enough.

You are going to need some sort of cable to go from the iPod to the audio system of the room.

The iPod has an earphone jack. It accepts a "mini jack".

Sound systems have an input jack of some sort. It may be a mini jack or something else. RCA (Radio Corporation of America) jacks are common on such equipment, they are bigger than mini-jacks. Furthermore there are probably jacks for left and right stereo signals. So what you probably need is a cable with a mini jack on one end that splits into left and right RCA jacks. Take a look at this http://www.monstercable.com/productPage.asp?pin=135

Now that being said the sound system may have some sort of connector or even has some options for several types of inputs.You are going to need to do some investigating on your own. If possible I recommend you talk to the facilities person for the room that you are using.

Skip over the iPod forums and you may get some A/V folks that can give you more advice and point you in the right directions.

The cable would be same, mini jack to what ever the sound system accepts. Now to complicate things if the sound system has an optical input you can go optical from the iMac.

Yes, talk to the facilities person. Also Google PC to sound system and see what you can find, some sites may have diagrams that could help. I just did that and found this http://www.geeks.com/pix/techtips-SEP15-05.htm

Gotta runI am off to Pizza Depot for one of their $5.00 loss leaders, have a good evening.

Julie,
All the responses from the other poster are right on. As well, you figured it out for yourself... that is, the headphone jack is what will be used - and the headphone jack on the computer is the same as the headphone jack on an iPod.

I have connected iPods and computers to PA systems used by bands and auditoriums... and a couple of times a year, I show movies at the end of the cul-de-sac or in my back yard and run the audio through a PA system my band used to use.

A pair of external speakers with enough power to fill an auditorium of 400 people will need a bit more than regular computer speakers. There are speakers out there with their own built-in amps (Anchor makes some, but at ~$350 each for the little 50-watt units <http://www.csnsupply.com/asp/show_detail.asp?sku=AN1059&refid=XT4%2DAN1059>, it might be more than you want to spend... plus the low-end on these guys is not so hot.

If you are thinking that you could get some PA-type speakers like JBLs or Yamaha's (made for PA systems) from Guitar Center and simply plug them into your computer, I suppose you could, but the problem is that the computer's amp (or the iPod's for that matter) can't push enough power out to drive the speakers efficiently. Turning the volume all the way up on the iMac or iPod will over-drive the amp and make the audio sound REALLY scratchy.

You need to be able to plug into an external amp. Note that the Anchor's I eluded to above have their own built-in amp. In auditoriums, typically, a person talking will require a microphone. Multiple people - multiple mics - sound sources. Just consider the iMac or iPod as another sound source. In order to control multiple, simultaneous, sound-sources, a mixing board is used.

Recap: Sound source (mic, stereo, iMac, iPod, etc...) connects to mixing board. Board connects to Amplifier. Amp connects to speakers.

Connecting the sound source to the Board can get interesting. Most mixing boards can accept XLR connections or 1/4" plugs. I presume you don't need the iMac on stage, so that means it can reside next to the board.

The easiest way to connect to an external sound system is to use a short cable "tail" that connects to the headphone jack and has open connections. Presuming you might consider connecting to a home stereo at some point, here's my recommedation - and this is my OPINION only... there are lots of ways to do this...

Shopping list:
1 short cable "tail" 1/8" headphone to 2 RCA female jacks
1 RCA male-RCA male audio cable (no longer than 25 feet)
2 RCA female to 1/4" male mono adapters
Optional - if the board requires - 2 1/4" female to XLR male adapters

1) The short cable "tail": One side connects to the iMac's headphone jack and the other side has 1 RCA female left and 1 RCA female right.

2) A longer (no more than 25 feet) audio cable that has 2 male RCA connectors on each end... The two male connectors on one end will plug into the female connectors on the short cable tail (above, #1).

3) Using 2 RCA (female) to 1/4 inch (male) adapters, plug the two open RCA male cable ends (from #2) into RCA female side of the 1/4" male adapters.

4) Plug the 1/4 inch male plugs into available channels on the board - it is possible the board does not take 1/4" in, so the 1/4" to XLR adapters might be needed.

The person who runs the board will likely not have all the adapters - but ask them first, because they might.

If you can't locate the iMac near the board because you need to be closer to the projector, you might need more than 25 feet for the audio cable... inexpensive audio cable will start to pick up some hum... again, the person responsible for the audio at the site may have some suggestions... that might include other, different XLR adapters.

The amp in the InFocus will most likely not be enough to give you what you want. They are designed to fill a meeting room - not an auditorium.

Ideally, when you do get connected to the PA system in the auditorium, the iMac volume level should be no more than 1/2 way up - then let the PA volume and gain levels (and the person responsible for the sound) take care of the rest.

If you need the iMac on stage, you will need to use available on-stage XLR connections normally used for mics - these will typically be XLR females. You will need two of these - so it gets a little interesting. You might also need a LONG video cable to get to the projector... Do a site survey with the AV person and make a list of what you have - and what you need... and don't forget extenion cords and maybe a power strip for AC power for the iMac and the projector...

GOOD LUCK!

cool... more details on the room.

Presuming you ARE working from a stage AND there are mic jacks on the stage:

Audio:
I did this recently for a Macintosh User Group meeting... Using a small 4-8 channel mixer (if one is available - if not, keep reading), connect the iMac to the the small mixer previously described. Connect the "Main Out" via XLR cable to the mic jack on stage. iMac audio level at 1/2... small mixer audio level at about 1/3 and gain (if it has a separate knob) at about 1/2... and let the main board operator take care of everything else. Since you are feeding into only one mic jack on the stage, this set up is mono only. Stereo capabilities will also depend on the main board and amp set up, so I won't go there). If you need to adjust sound and the main board is not accessible, up the level and gain on the small mixer first - if you need more, LAST recourse is to increase the iMac's audio level - when is starts to sound scratchy, back off until that goes away.

Guitar Center has several small mixes <http://guitarcenter.com/products/dispDeals.cfm?sel=7>... Behringer is another one they carry in their sotres - but not advertised on the web site. They are all around $150 to $300. If you'll never use it again, it may not be worth it, but the site manager might be interested. I generally use them for a drum-set (which can use 5 mics or more - if synth drums are used, too) - or this sort of "can't get to the board, so this 'pre-board' will have to make due". At the Mac User Group meetings, the main sound board is locked up in a back room, but always-on so the school principal needs only plug in a mic and start talking.

If a small mixer is not available, then feeding the left and right audio from your computer into a single on-stage mic input jack is the way to go. In the previous post, one of the shopping items was a 1/8" male head-phone to left-audio/right-audio "tail". Instead of that, get a 1/8" male stereo headphone to mono RCA female. This connects from the iMac headphone jack to the male RCA audio cable on one end. The other end connects to a female RCA-1/4 in male... which connects to a 1/4" female-XLR male... which plugs into the stage female XLR mic input.

If there are no mic jacks on the stage and the site manager is using a snake, then just treat the XLR connectors on the stage-end of the snake like you would if you were plugging into the board itself. The site manager should be able to assist with this.

Video:
Presuming you already have the Apple video converter tail for your iMac, you can get a VGA video cable as long as you want... Fry's Electronics (Outpost.com online) has LONG ones... http://shop3.outpost.com/product/4473316?site=sr:SEARCH:MAINRSLTPG There are likely other sources, but Fry's is nearby for me. If this link does not work, got to Outpost.com and search for "vga cable".

Measuring the spot from where you will be speaking - presuming the same place the iMac is - to where the projector will be and add at least 10 feet... remember, the cable on the floor needs to get up to the iMac (on a podium) and up to the projector (on a table?). We live in a 3-dimensional world...

Other logistics...
Don't forget duct-tape... the cables need to be taped down to the floor so people don't trip. The site manager might take care of this, but one can always use duct tape elsewhere, so just be sure to bring a big roll. Heck, leave it with the site manager if that person does take care of it... I guess that's up to you.

If at all possbile, make arrangements with the site manager and set up everything to be sure it all works - and you are comfortable with the sound-levels, video cable and all the other hook-ups. Presuming no one else is around, doing a short test with your computer and everything plugged in a couple of days before the FIRST time will ensure you have the right cables, adapters, and even sound levels... so that you have time to recover and get stuff just in case... AND be sure to mark all your cables and adapters and gear so everyone knows who owns what. White tape with your name (use a Sharpie) is easiest (though removeable - so pros and cons to that).

... and if you are speaking - hence, mic'd up - a handheld mic (better yet, a wireless lavalier) should be used so you don't have to scream at your audience - and you want to be comfortable with that, too. If handheld, is there a mic stand? Is it connected to the podium? Will that get in the way of the iMac monitor? A stick or boom mic stand (not part of the podium) might be in order - the site manager should be able to address this since you indicated there are mics... If you use a small table next to the podium for thee iMac, a lavalier (clip-on mic) would be easiest since it will leave both your hands free to use the computer while you are speaking. If a lav is not available, a couple of mics (one at the podium and one at the iMac on the table) might be in order. A wireless hand-held mic will also be useful if available (hold mic in one hand while using mouse with other) which would make the multiple wired mics unnecessary.

By the way, what's the show about?

HAVE FUN!