Ipod Your Digital DJ

How to Start the Party with Your Tablet or other Hi-Tech Gadgets

by Bob Moffett

If you're a tech-savvy consumer you may be interested in using an iPod, tablet, or laptop computer to supply music entertainment and other media for your event rather than hiring a DJ or band. If you already own one of these items and you've acquired quite a bit of your favorite music then, why not?

It can of course be the perfect and simple solution for many kinds of gatherings. Modern audio-visual and IT equipment is self-detecting, making your experience literally just plug and play. However, there is still plenty of older legacy systems out there and if you are connecting with other people's gear you'll need to be adequately prepared.  Video interfacing in a non-plug-n-play circumstance can get rather technical, so this article will focus on audio - presuming you intend to be your own DJ. If you're planning a large formal event such as a wedding however, I recommend taking the time to consider if your interests would be better protected using a full service disc jockey or seeking professional audio-visual support.  Otherwise, if you remain undaunted then read on!

What you'll need
In the absence of a direct device port, bluetooth, or other wireless communication you will have to manually patch your audio into whatever sound system will be used.  iPods, Tablets and computers use an audio output connector called a stereo sub-mini phone plug (3.5mm). This is same connection where you attach your headphones.  To make this connection you may need a stereo "Y" cable to convert your sub-mini phone plug into a pair of connectors that  mate with the sound system. The most common are pictured at right.

Strange Noises
One important note about computers: beware of ground loops and Radio Frequency noise (RF noise) generated by these devices. This appears in your audio as a rasping buzz (RF) or a low hum (ground loop). To eliminate this problem a special version of these cables is available that includes an isolation transformer built into the cable.  This breaks the electrical connection that allows noise into your sound system while letting the actual music signal pass unchanged.

Keep in mind that the volume levels on your computer affect the amount of sound available to be amplified.  If the sound system has no independent volume control your device will be the way to adjust levels. If on the other hand the system does have volume controls I recommend you set your device to about 70% of it's loudest setting and use the sound system to adjust the final volume. If you have little or no volume at all - first check the volumes controls on your device and then every device in the chain.

Troubleshooting
If you adjusted the volume controls and can't  get a reasonable sound level or the sound is terribly distorted, it is likely due to an impedance mis-match. Avoid connecting your device to any sound system inputs marked phono or mic since your device is likely to overload those inputs. If you have to connect your device to a phono or mic input use an impedance matching transformer.

If your audio is clear but simply not loud enough you will need an additional piece of equipment  to boost the signal gain before it is fed to the audio system. This may also be necessary if you want to use a microphone for announcements and the system does not already have a mic input. Both of these needs can be resolved by adding some type of mic/line mixer, also known as a pre-amplifier

A simple and inexpensive solution is a portable DJ mixer sometimes called a "scratch" mixer because of their small size. This will give you not only a mic input but additional inputs for a CD player or other device as well. Products are also available that combine the basic features of a DJ mixer with built-in docking stations for your iPod, or tablet. These items simplify this whole process by combining everything we've discussed so far into a single unit that you can connect directly to your sound system. To use one of these all-in-one units simply connect the output directly to your sound system's amplifier, or to any line input (CD, tape, Aux) of your home stereo.

Developing Playlists
The advantage of being your own DJ of course is having control of your own music program! Just remember to cater to the needs of your guests as well. and select music appreciated by everyone for the best response.  It's not necessary that you anticipate in great detail what everyone will respond too. Instead, expect that change will be needed and plan for it. Create smaller separate play list "chunks" that you could easily juggle around when changes need to happen. This will make it easier to bump-up or postpone that high-energy set, or quickly recall that romantic series you created for just the right moment. If your computer or device allows you to group these play lists for a consecutive run then your job just got even easier.

Computer DJ Software
If you are already using software such as iTunes and Windows Media Player you can get good results without adding anything more.  There are also numerous softwares designed specifically for DJ use including open source and free shareware. MIXX is one such example of an excellent DJ software that is open source. DJ software will automate your play lists while giving you instant access to changes on the fly and many other tools of the craft. Whatever software you decide to use, be sure to check that your computer meets all of the hardware requirements with regard to processor type and memory. A mismatch could cause your system to "hiccup" or freeze in the middle of your music playback. Watch your resource meter while evaluating the products. Software that demands a great deal of your system resources will be more prone to problems should another application be opened while the music is running.

Sound Systems
You can rent an appropriate PA system if your event is large. Explain to the vendors what you are trying to do and most will be happy to see that you have everything you need. Some will even deliver right to your event site and pickup after completion. The size of the system you need is something to seek assistance in selecting. How much power you need should be based on the number of people you expect to play for which matters more than the size of the room. Figure at least 2-3 watts per person for a conservative adult group, and 4-6 watts per person for younger groups. Younger audiences that prefer dance and hip-hop styles might benefit from a sub-woofer that will enhance the bass portion of the music without straining the main system. It is better to be somewhat over powered and lower your volume than to be under powered and risk system failure

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