The Do It Yourself Silent Disco

with 21 Comments

I promised some DIY projects on here but have yet to deliver. So here we are. This is your only warning, this is a nerd heavy wall of text. Bail now or be prepared to be bored to death!

If you have been to a music festival there is a good chance you already know what a “silent disco” is. For those of you who don’t know, I will explain it shortly. In some ways this is one of my most ambitious projects yet. Not only could the success of the project bring the silent disco to the little guy, it could also rewrite the standard model of operation for silent discos everywhere.

The silent disco is a concert that attempts to eliminate noise pollution by transmitting the sound to the listeners ears via headphones rather than traditional ambient methods. The elimination of noise pollution is beneficial for nearby campers, nearby residents, and is a good way to keep the music going late into the night when excess noise is traditionally unwelcome. The standard model silent disco transmits sound through the use of Bluetooth, FM, or Wi-Fi standards in combination with headphones that receive and then play the incoming signals at the users ears. If you’ve been to one you know that it can be an eerie experience at first. People dance, clap, even cheer, but if you aren’t listening it looks like everyone just ate too much acid. If you’d like to read more on the silent disco head on over the wikipedia page.

Here’s a video that does a pretty good job of illustrating the silent disco.

 

Why have I decided to tackle the silent disco? Firstly, silent discos are fun and bringing that experience to more people would be a good thing. More importantly, the silent disco will likely play an increasingly important role in the landscape of music festivals in years to come. As there appears to be a boom in small festivals which are outcropping regionally and attract similarly regional attendances there is a growing audience for such technology. As festivals face regulatory challenges, not in my back yard types (NIMBY), as well as a host of other barriers, the importance of the silent disco could rise. Additionally, the high technology requirements of the silent disco make them cost prohibitive at festivals and concerts where funding isn’t overly abundant. That said, the widespread infusion of high technology devices into the general population, specifically smart phones, makes a silent disco possible through the use of consumer grade hardware and software.

Summary

Use Apple’s AirPlay standard to transmit sound via Wi-Fi to several users who receive the signal via compatible devices such as iPhones, iPod touch, as well as Android devices thereby creating a “silent disco.” These devices will be operationalized in an environment consisting of consumer grade software and hardware in an attempt to achieve a low cost yet effective silent disco system.

Design goals:

  • Budgetary commitment – the lower the better (duh…)
  • Interface with DJ/Band setup for broadcasting
  • Broadcast to a spectrum of commonly used mobile devices
  • Eliminate specialized headphone hardware
  • Easy setup and tear down
  • Provide a cost free listening environment
  • To support 40 listeners at base system
  • Provide an easily expandable platform

Hardware (current test bed):

  • 2012 Macbook Pro (OS X 10.8)
  • Dell Optiplex (Windows 7)
  • Airport Express Router (A1392 Gen)
  • Airport Extreme Router (5th Gen)
  • Netgear Wired Switch
  • Three iPhones for testing
  • Two iPads for testing
  • One Apple TV for testing
  • Sony MDR-V6 Headphones
  • Dayton Audio D652 Satellites

Software:

  • iTunes 11 OS X
  • iTunes 11 Windows
  • Airfoil for OS X
  • Airfoil for Windows
  • Airfoil Speaker for iPhone/iPad/Android (all version are free)

Cost

The cost of the system only includes the hardware required to create a base level system. The cost analysis also makes the assumption that an adequate computer is already available.

  • Apple Airport Extreme $200 Retail ($80 used)
  • Airfoil for computer $25 (both PC and Mac)

Total cost retail: $225

Total cost used: $105

Setup

Configuration was not difficult. Let’s start with the hardware. My Airport Express is only capable of handling 10 devices at a time, that immediately violated one of my design goals. As a result, I purchased a used but “like new” Airport Extreme on eBay for eighty dollars including shipping. This got me up to 50 theoretical users from a single router and supplied better signal range than the Airport Express variant. I powered the router via the supplied power pack and a wall outlet and then hooked an ethernet cable from the port of my Macbook to one of the ports on the AirPort Extreme. The modem port does not get used. The DJ or band need only to produce a single output in 3.5mm headphone jack form that gets plugged directly into the mic-in on my Macbook. Finally, each user will need an Andoird or iOS device as well as a setup of compatible headphones.

Now we are ready for software. I installed Airfoil for OS X on my MacBook. I just downloaded and ran the installer. Each device that I push music to will require an Airfoil Speakers install as well. This is available on both iOS and Android. It is free in each respective app store for download. Again, just download and install.

Once installed I only need to connect my device to the Wi-Fi connection that I created on the port Extreme. To setup my Airport Extreme I used the OS X native Airport Assistant. Windows users will need to download this.

Use

To start audio exchange I just turned the Airfoil software on at both my Macbook and my iPhone/device. At my Macbook it only takes a few seconds for the device to show up as “available.” To send audio from a DJ or band I simply select the line-in option from the top of the Airfoil software on my Macbook. During my tests, I used iTunes audio rather than a DJ or band. Once a device is shown as available on my Macbook I then can turn on the audio stream to that device by clicking the music note to the right of the device name, when the icon is blue it is actively being fed audio. Success!

Testing

Two testing configurations were arranged. Both tests were carried out in my small apartment.

Configuration One – My home network is already configured with a Dell Optiplex hard wired to my AirPort Express.

Configuration Two – I used the MacBook Pro connected to the network via ethernet. This time the network consisted of a AirPort Express and Airport Extreme in roaming mode. Both routers remained in close proximity to each other.

Configuration Three (distance testing) – MacBook Pro connected directly to the AirPort Extreme. Used iPhone with headphones to receive audio. The AirPort base station was placed on a second level balcony that is approximately 20 feet from ground level.

Devices – I installed the the Airfoil application on three iPhones and two iPads. For additional load testing I streamed to two Apple TV’s. I used an iPhone with the Sony MDR-V6’s  and walked acround both in my apartment and outside of it to test distance capabilities.

 

Preliminary Results

Configuration One – Playback worked without connection losses. Sound quality was average or slightly better than average on the Sony headphones and Dayton Audio speakers. There is a detectable latency in play of about 3 seconds. When starting or pausing playback at the Dell Optiplex it took around 3 seconds to affect change at the device. This means that the system is not suitable for use as a live studio monitor. DJ’s or bands will need to figure out live audio monitors on their system separately.

Configuration Two – Playback was again very stable. Sound quality remained average or slightly better than average. I connected seven devices in total to the feed. Playback was consistent and without drops. The approximate three second latency remained.

In both configurations, tests outside a 25 foot radius of the router resulted in signal drops and irregular feed. When traveling outside the signal had to pass through several brick walls and is likely a consequential factor to low signal strength at a distance. Future tests will be performed in the outdoors to evaluate obstruction-less performance.

Update 1 – August, 16

Distance testing –  I connected headphones to the iPhone and started walking away from broadcasting station. I was able to go nearly one full city block away from the base station and maintain music without drops. I estimate this distance at around 300 feet. It is important to note that this was with little to no obstruction in the sight-line between me and the base station. Signal dropped dramatically at the one city block distance. Additionally, as the number of obstructions between me and the base station increased there was a noticeable sound performance loss. This was true for connection and sound quality. The obstructions consisted of buildings, both brick and wood. However, obstructions like this are are not something you would typically encounter on a dance floor.

This test also highlights the potential gains that might be experienced from locating the AirPort Extreme base station at a high elevation relative to the dance surface. Mounting the Airport Extreme a few feet over crowd (12 to 15 feet off the ground) should minimize human obstruction of the signal and insure good service for all users.

Caveats and Notes

If at some point I need stronger signal over a larger area, need to support more than the 50 theoretical users, or both, simply applying an additional router in roaming mode (Airport Extreme instructions) should do the trick. In fact, the network should be completely scalable simply by adding routers as throughput becomes too low or user number increases. It should also be noted that this setup requires no outside internet connection or internet service provider as it functions exclusively on the local area network (LAN). Additionally, there are plenty of sources where people have used 8 or more Airport Extreme units to create a large business class network again showing the scalability of the setup.

Router hardware could be an issue as throughput is likely a key factor in reliable playback. Airplay function, while efficient, can be degraded with low signal strength or if outside interference is present. It must also be said that good reliable routers with high output signal is probably desirable. This is why I stuck with the Apple products as I personally have bad great luck with them. That in mind, I suspect that there are a bevy of quality routers on the market that would do the job while being a little easier on the pocket book.

Note (August 16): Roaming mode may not be the best solution when needing greater throughput as devices will likely drop signal when switching from router to another. Instead, leaving each router setup with a standalone SSID might be better. This also could allow for manual allocation of users across the network.

Links and Resources

Apple Airport Express Client mode Help Document – http://support.apple.com/kb/HT2272

Apple Base Station Help Document – http://support.apple.com/kb/HT4145

Apple Airplay Setup Help Docoment – http://support.apple.com/kb/HT4587

Rogue Amoeba Airfol – http://www.rogueamoeba.com/airfoil/

Update 1 – http://chrislivengood.net/wp/do-it-yourself-silent-disco-update-1/

Disclaimer 

As this project is compiled completely on consumer grade hardware and software I reserve no attachments to the system in any way. In fact, I encourage you to setup your own system and begin sharing the silent dj love. If you do test the system, make alterations in hardware or software, or have information to add I encourage to comment below!

 

21 Responses

  1. […] This content has been appended to the original artcile which can be found here. […]

    • Mason
      | Reply

      Hello, this is great. One quick question. Must you be connected to the internet for this to work? I am going to the beach, far away from internet connection and want to make it work. Will it work?

      • Chris
        Chris
        | Reply

        It should also be noted that this setup requires no outside internet connection or internet service provider as it functions exclusively on the local area network (LAN).

  2. Forrest Meyers
    | Reply

    So is the Airport Extreme necessary, or will any modem-type wifi provider work?

    • Chris
      Chris
      | Reply

      I have not tested any combination modem/routers, though it should work. It is important to note that system will work sans internet service provider, thus a modem is not required. That said, most routers should work fine.

      • Forrest Meyers
        | Reply

        Thanks! Looking forward to trying this!

        • Chris
          Chris
          | Reply

          Be sure to come back and post your results. The system worked very well for me, but I’d like to build a small database here for others to read should they want to try it.

  3. […] See a tutorial for this idea. […]

  4. Scott
    | Reply

    My experience is that this design will not work for a silent disco. I have tested it with an iPad Air, iPhone 4s and Macbook pro (mid-2012) and I believe a Netgear brand wi-fi router. I am very skeptical that the wi-fi router is the problem – it should have enough throughput. Audio playback is awful with many artifacts and playback speed warping. I’m starting to believe the only thing that will work for this is a small FM transmitter (this is actually how all wireless disco’s are implemented at the moment.)

    • Chris
      Chris
      | Reply

      I experienced the opposite once I got things setup properly, this was especially true in open spaces such as my yard. As you mentioned, throughput should have been fine. So why wasn’t it? You should inspect your wifi arrangement and the setup of your Netgear router, especially fragment threshold and RTS threshold.

      • Scott
        | Reply

        I’ve been in touch with the developers from Rogue Amoeba. They’ve provided me with a developer’s build to address the problems I’ve been having. I’m pretty sure it’s a software reliability issue. I’ll see if I can improve my results at all by tinkering with the network. Thank you for your response.

        Scott

  5. Christopher Rasch
    | Reply

    Thanks for posting this! I was looking for DIY/Open Source disco systems and found your post:

    https://www.facebook.com/crasch/posts/10153545553790312?pnref=story

    Look forward to trying it out!

    • Chris
      Chris
      | Reply

      Hi Chris,

      I hope it works out. I tested this system a while ago and found it to be good, but haven’t played with it much since.

      Good Luck!
      Chris

  6. Suryateja
    | Reply

    Thanks for this awesome tutorial.
    I plan to organise such a Silent Disco at our college fest. The expected crowd is 500 people. How do I manage to make the transmission strong enough to do that?
    Also, it’s a bit impractical to dance with mobiles in hands.
    Would you suggest FM transmission?
    Any good tutorials on fm transmission?
    The area to be covered would be 1.5 soccer pitches. Or around 150 metres.

    Thanks in anticipation!

    • Chris
      Chris
      | Reply

      Hello!

      It could work for larger crowds, but you would want to use professional grade hardware instead of the Apple technology I tested with. Having a good (professional) network technician would almost certainly be required. As far as holding the phone goes, that’s what pockets are for.

      You may consider a more industrial grade system for that large of a crowd. Plenty of systems out there these days. I published this article over two years ago, and the technology has progressed.

      Regards,
      Chris

  7. liz
    | Reply

    would each person listening to the silent disco have to purchase airfoil for $29?

    • Chris
      Chris
      | Reply

      Hi Liz,

      I can see Mr. Smalls from my home. We are just a bridge away from each other.

      Airfoil is free from the app store for mobile users. If you wish to stream music to those users via a laptop you must purchase the airfoil software for $29.

      Regards,
      Chris

      • liz
        | Reply

        Hey Chris,
        That’s crazy that I randomly found your article on the internet and you’re right next door. Thanks for the reply. We are thinking about putting a system together for a new Mr. Smalls project. Would you be interested in helping out?

        • Chris
          Chris
          | Reply

          Hi Liz,

          I want to note that I wrote that article over 2 years ago. If you plan to use my system, please make sure that this software and the accompanying apps are available still. I wouldn’t be adverse to helping out, but I will say that I have a lot of projects on my plate currently. Depending on the timeline of your project I may or may not be able to help. Finally, if you plan to implement on a fairly large scale, you may be best off hiring a real network engineer as they could best optimize both the hardware and software for this type of setup.

          – Chris

          • liz
            |

            Ok great, I’ll keep you posted and would welcome your participation to whatever degree you are interested and available for.
            Thanks!

  8. Airport Express Model A1392 Manual
    | Reply

    […] The Do It Yourself Silent Disco – Sav0r the adventure. – Thanks for this awesome tutorial. I plan to organise such a Silent Disco at our college fest. The expected crowd is 500 people. How do I manage to make the … […]

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