The dock in all its acrylic glory
I came home from the last trade show with a pretty interesting little piece of kit. The K-Array Ecodock is an acoustic coupler for your iPhone4 or 4S. The piece appears to be made out of acrylic and your iPhone rests in the top of it and creates a horn the matches up to where the speakers on your phone are doing their level headed best to keep with your demands for output.
K-Array is an Italian speaker company that knows a little bit about taking a really small speaker system and making it sound and perform like it is a lot bigger. They decided to apply that expertise to the iPhone’s limited audio output by creating the Ecodock.
Shown amplifying my phone’s output
If you don’t know what a horn is there is some pretty in-depth information here on the Wikipedia for explaining what they are and how they work.
Even if you are not interested in the math you have likely taken advantage of the characteristics of a horn. Ever cupped your hands around your mouth when shouting to try to get a little bit more volume, or grabbed a cheerleaders megaphone and talked through it? These are both classic examples of the horn technique.
The iPhone rests in the cradle and the audio is redirected from the bottom of the iPhone out the front of the Ecodock. The perceived difference is pretty impressive. Overall volume was obviously louder and mid-range information like guitars and vocals were noticeably more forward.
I decided to do a little bit more testing so I set up my iPad running an RTA – Studio Six Digital” target=”_blank”>RTA package from Studio Six to measure the output of the iPhone with and without the Ecodock.
The iPad was about 2 feet away from the iPhone with the microphone facing the Ecodock. Measurements for just the phone were taken with the phone on its back so that the speakers were facing the iPad and I lined them up so it was even with the edge of the Ecodock to keep the distance as similar as possible.
The first tests I ran were using pink noise which is a static sounding noise that has an equal amount of power in each octave making it useful for measuring a sound system’s performance.
The measurement for just the phone looked like this.
Pink noise- no ecodock
This graph shows pretty obviously the deficiencies in the iPhone speaker. Small drivers mean not a lot of low frequency output. You will not be driving a rave with your iPhone anytime soon without additional equipment!
A speaker horn is effective based on the width of the horn, and based on the fact that the horn gap is basically 4 kilohertz in width, we would expect it to be the most effective around that frequency.
Measured in hz and in inches…
Below we see the same pink noise signal being measured with the iPhone inserted in the Ecodock.
Pink noise- with ecodock
We can see from the RTA plots that the Ecodock is giving us about 6dB of gain at 4K but it is also raising the general level of the signal from roughly 2k up to about 10k. So we are going to get a significant increase in midrange and some high boost but not a whole lot of low frequency improvement.
Of course test signals are one thing, what about on actual music?
I repeated the same test with some uncompressed audio that I had on my iPhone (Last Plane Out – Toy Matinee” target=”_blank”>Toy Matinee’s Last Plane Out if you are interested…)
Full range music- no ecodock
Full range music- with ecodock
Again, you can see in the comparisons that there is a general increase in the level from about 1k to about 10k.
Subjectively, I do hear more bass out of the Ecodock than with iPhone by itself. This may because I am hearing the overtones of the low frequency instruments being brought out.
The effect is pleasing and does make the music louder with no requirement for power or additional heavy equipment.
There are a couple of downsides to the Ecodock. Because the horn needs to couple tightly with the speaker on the iPhone to work well, you can only put an iPhone with no case into the Ecodock. If you are into the naked beauty of the iPhone than life is good for you, but if you are a klutz at my level, this may not be a perfect solution.
Conclusions:
Acoustics does not give us too many places where we can actually get something for nothing. One of these instances is having a speaker, typically a subwoofer, against the wall or in a corner and getting more output from it because of in-phase reflections.
The other classic one is a horn, which generates about 6 dB of additional output. The challenge on this is getting the geometry correct to get the gain in output in a pleasing way.
To my ears the Ecodock does a pretty impressive job of this and has the added benefit of requiring no batteries.
K-Array Ecodock $19.95