Amplify an iTouch output

[grandpa06]

I will try to explain the situation.
We would like to take an iTouch or any iPod and connect it a a scorers table to our speaker system. Of course, this is a very long run on wiring. Does any one know of some way to put an amplifier with an iTouch or any iPod. It would make it easier for the announcer to control the iPod at the scorer's table rather than trying to coordinate with two people, one at the table and one in a control room.
Thanks
DR:shake:

[kornchild2002]

Sure, there are amps that will work with any iPod. The take the iPod's headphone output and amplify it. The only thing is that these amps are around $100-$150. I don't know what kind of budget you are on but another option would be to not use an iPod at all.

What you could do is purchase an older AirPort Extreme base station and use a notebook to stream audio to that. Put the AirPort Extreme base station right next to the audio input and connect to it (through wi-fi) using a notebook. I think you can find one of these base stations for around $75. It would be a less expensive solution to using an iPod and probably provide better quality. Then again, you lose the ability to have people bring you their iPods (or Zunes, Zens, whatever) their play their music.

[S2_Mac]

What you're looking to do is called "converting an unbalanced signal into a balanced signal." (Think of an unbalanced signal -- the output from CD players, tape players, turntables, guitars/basses/keyboards, and iPods -- like DC current: it doesn't travel very far, and is prone to pick up line noise. A balanced signal -- microphones, mixer outputs, amp rack interconnects -- is like AC current: it travels very far, and inherently rejects noise.) Unless the run from the table to the mixer is under 20 feet or so, an amplifier isn't going to do you any good (an amp's output is "DC"). A balanced output, OTOH, can easily travel 400 feet without significant noise or signal degradation.

There's basically two ways to "balance" an iPod's output:

1) a mixing board at the scorer's table. If the announcer has a small mixer at the table, with 2 free inputs, you've already got 90% of what you need. Just get some kind of cable to connect the iPod's docking connector to the two inputs and then put the iPod in the mix that gets sent to the amplifiers.

2) a "direct box" at the scorer's table. Direct boxes (aka "DI") convert an unbalanced signal (the output of a CD player, or an iPod, for instance) into a balanced signal (a microphone output, for instance). You would need to connect the iPod's dock connector output to the DI's inputs, and then provide one or two microphone cables to run that signal to the mixer.

For getting signal out of the iPod's dock connector, use any iPod "dock" or (my favorite) a PocketDock (http://www.sendstation.com/us/products/pocketdock/lineout-usb.html). Cost: $30 to $100. If your dock doesn't come with cables, add $15 for cables/adapters to get the signal into your converter.

If there's a mixing board at the table, it's almost sure to have 2 or 4 channels set up to receive RCA inputs (the typical connector type coming out of an iPod dock); if not, you'll need something like RCA-to-quarterphone adapters (maybe $10 a pair). This is the optimal solution, since the existing cable from the mixer to the amps will carry the iPod signal; no new long-haul cables needed.

With a direct box you'll need to get iPod dock connector output into the direct box inputs, and then use microphone cable(s) to bring the direct box output to the mixer. This can add up if you don't have someone who can make the cables for you; figure on a buck a foot per cable. Suitable DI boxes run from $60 for this ART DTI box (http://www.sweetwater.com/store/detail/DTI), to $85 for this Ebtech unit (http://www.sweetwater.com/store/detail/HumXLR) (and add $10 to convert to the Ebtech's quarterphone inputs) to (my favorite) $130 for this Whirlwind pcDI (http://www.sweetwater.com/store/detail/pcDI/). (I like the Whirlwind because it has a stereo-to-mono combiner built in, thus requiring only one output cable...and because Whirlwind is good stuff ;-)

Or, you could add a mixer to the scorer's table -- 4-channel boards are out there for $150 or so; a wide range of stuff for less than $300. Assuming you don't need stereo, a single mic cable will take iPod and microphone signals to the "real" mixer at the sidelines.

[bobb-mini]

Holly crap Mac, u oughta be a professor. :D In all these years of audio, I never bothered to find out what exactly balanced is other than $expensive.

Depends what the budget is at this point.

[S2_Mac]

LOL! To make the "current" analogy a little better, think of balanced as being simliar to U.S. 220 volt AC -- it's the same waveform, mirrored along the horizontal axis (aka the neutral). You can thank the phone company for balanced circuits -- that's how they got phone signals to travel farther than a few hundred feet before needing an amplifier. It's exactly the same principle used in Ethernet, or any "twisted pair" circuit.

Can't have too many DI boxes!

[kornchild2002]

If this is the case then wouldn't it be better to use a wi-fi music device (and notebook/computer) due to cost effectiveness (unless the OP already has some of this equipment). Music can be transmitted over great distances using wi-fi especially outdoors. Hell, I can even transmit music (to my AirPort Express base station) indoors and it is about 60ft away (I have yet to find its limit).

[bobb-mini]

WIFI is a good solution. Physical cable = too much maintenance. Assume power available on both ends.

[pm7771]

S2_Mac I was VERY impressed with your answer(s) being in the sound business for a long time. One thing you didn't mention I just thought of is todays baluns - a little transformer box - and it take 2 - one for each end. The beauty of these is that you just plug in a CAT-5 network cable between the two, and now you can pass a long distance on inexpensive unshielded wire. So you'll end up with dual ( stereo ) RCA jacks. I'm sure with a little looking you can get hooked up with 250' of cable and a pair of baluns plus a mini to RCA cable - for something in the $150 range, and maybe better. Pretty good overall for the sound you'll get, which should be really fine.

[S2_Mac]

I wouldn't...but I'm an old fart ;-) First, there's no knowing what else is in the air -- security radios, pager systems, ad hoc wireless for reporters/onlookers, dirty motors/lighting, etc. Keeping everything balanced, in a cable, avoids just about every interference problem the world will throw at you. (O'Toole's Corollary to Finagle's Law: The perversity of the Universe tends towards a maximum.)

Wireless introduces more fail points -- a thousand things can go wrong on the laptop; a hundred things can go wrong with the receiver. With a balanced signal in a cable, potential problems are reduced to mere tens, and repair is much easier. (Murphy's Law: If a part can be installed wrong, it will be.)

Then there's what every sound tech comes to learn: As soon as it's out of your sight, it grows legs. I'd much rather lose a cable than an Airport Express. (During a battle of the bands, people think the techs get onstage quickly because they're devoted to keeping the show moving right along.... Naw, we just want to make sure the outgoing band doesn't walk off with our mics and DIs ;-)

The OP didn't specify the venue, but for all the sporting events I've done, the scorer's table is at least 100' from the processing racks; usually much more...not ideal for WiFi. The environment could be wet, or cold, or boisterous...not ideal for laptops. DIs and cables are passive devices. Give them decent care and they'll last just about forever. Throw the worst conditions at them and they'll work. Lose 'em and you're only out a hundred bucks.

[pm7771]

S2_Mac - I agree on the wireless - wifi digital works wonders in this digital age- as digital is self correcting - but the audio the original poster waqnts to send is analog - and I've never seen a fully reliable system - for short distance analog audio. Even the best wireless mic systems aren't bulletproof - and today they're challenged by digital TV signals - AND mono to boot!

[S2_Mac]

You talking about those "inline" transformers, aka "matching" transformers? (Looks like a barrel, typically 3 inches long with a quarterphone jack on one end and an XLRf on the other.) Yuch ;-)

Everything discussed here is a "balun" -- the name derives from balanced-to-unbalanced, and that's what the matching xformers are best at; matching a balanced signal's low impedance (over the air TV broadcast, for instance) to an unbalanced signal's higher impedance (coaxial cable); crucial to good video feeds. About the only place a barrel balun should be used in audio is when you're out of DI boxes and need to connect a low-impedance mic to a high-impedance input, like a guitar amp. (Some folks like ot use 'em to add some "color" to a mic.....)

The cores on barrels are small, the windings are stacked and narrow-gauge, and the shielding sucks (for audio). They oversaturate quite easily, the freq response is all over the board, and there's phase problems at audible freqs. (They work great for broadband, where you're happy to ignore anything below a few MHz ;-) A good DI box has a large "comb" core, separate windings, bigger wire, and much better impedance response. (Not to mention ground lifting, padding, shock resistance, etc.)

Hey, I'm old school; my first reaction is always going to be "stick a DI on it," and "run it over mic cable/snake cable." That's just the Bitter Voice of Experience ;-) CAT5 cable kinks/breaks easily and doesn't have any shielding -- might as well send invitations to all the HT radios in the area. Connectors aren't rugged, water intrusion is easy.

For all I know, this PA is Bose 802's with no controller box fed from Peavey power...in which case just about anything will work equally bad. But on the chance that the system is good, it deserves good gear. Some booster will step up with $200 so's he can hear Sirius blasting while everyone gets ready to rumble ;-)

[grandpa06]

Thanks for all the information. I will pass this all on to those that want to set this up. One of them has worked in radio broadcasting. He might have access to some of the needed devices.
Again thanks.
DR

[S2_Mac]

Good luck with it! In case the babble was a bit off-putting, the key thing is to convert the iPod's unbalanced line out signal into a "balanced" signal; the recommendations are a small mixer, a 2-channel DI box, and inline "barrel" DIs. Since mono is more suited to a typically wide venue (sports), you'll only need one cable (or "pair") to carry the signal to the mixer/processor. (Previously unmentioned -- if you use inline barrels, you'll need two cables, since the barrels provide no means to properly convert the signal to mono. Don't you dare try to convert the iPod's stereo signal to mono by using a "Y" adapter from Radio Shack -- something will get hurt after a while.)

If your radio guy can't get you a deal, try visiting a professional audio house. In my experience, there's always a few pieces of old gear they can part with for not too much cash, and if you chat 'em up a bit they often give you really good advice/help ;-)

[pm7771]

S2_mac - here's the link to what I'm talking about as the new boxed baluns I think are perfect. Note 2500' range over cheap CAT5 cable, full frequency response 20-20khttp://www.jobsitesystems.com/product_result.php?prodID=BT-SA&recordID=Cat-5%20Baluns&categoryID=Cat-5%20Baluns&catcdID=11&prdcdID=FG01376

[S2_Mac]

Wow -- took a lot of digging to find a price. Looks like retail is $70 each, and you'd need two. I could see using these for a fixed installation, where the cable could be shielded by properly grounded conduit, but I'd be very leery of using the cable in a concert/ad hoc venue. (Solid conductor cables break/kink too easily, there's no shield, and no microphoning protection.)

Interesting find...I'm gonna see if I can find anyone around here who's using them.