iphone accepting line level input?

wcben

Is there any way that instead of using a microphone, a line level signal could be input to the iphone?  This would help dramatically in the diagnosis of actively crossed over outputs from amplifiers, effectively taking the drivers out of the equation.

benfaber

Currently, there is no officially supported means for getting line-level signals into the iPhone, via the dock connector. We are keeping an eye on it, though.

jrgeek

Curious  Wha t did you mean by  "taking the drivers out of the equation" ?

A dc blocking attenuator could be made to put line level (or even  higher) into the mic input. Would that be acceptable?

wcben

Yes, I'll probably do a step down to make it work.  I'm using the app to evaluate frequency bandwidths coming out of actively crossed over outputs from amplifiers, I don't want to rely on inherently poorly designed speakers to affect what I monitor.

Riley Casey

There is this : http://www.ipodtouchfans.com/forums/showthread.php?t=9347

remorley

I just purchased SignalScope for the iPhone and generally like it a lot. However, it would be useful to be able to set the sampling frequency and recording duration of the time-domain waveform myself. It would also be useful to be able to capture the waveform to a data file to be emailed as well as to a photo as currently supported.

I don't understand why the App Store shows this app with "Line In" and stereo channels. That is misleading but I sure wish it were available!

Don't show non-existent features in the App Store.

benfaber

However, it would be useful to be able to set the sampling frequency and recording duration of the time-domain waveform myself.

Adjusting the time domain limits is possible with two-finger pinch/spread gestures inside the horizontal axis label area of the waveform display.

I don't understand why the App Store shows this app with "Line In" and stereo channels. That is misleading but I sure wish it were available!

Line-in has been available, via the dock connector, since version 2.2 of the iPhone OS.  You'll need a third party device, like the Belkin TuneTalk or the Tunewear Stereo Sound Recorder for iPod. We're planning to test as many of these devices as we can get our hands on and post the results on the site.

remorley

Thanks Ben,

Are you implying that it is ok for me to connect to the line in inputs on the dock connector?
I am a Electrical Engineering Prof who wants to experiment with the iPhone's line in features and not looking to publish (i.e., get Apple's blessing) any apps at this time. Does the SDK support input from both line inputs at 48kHz sampling rate?

Bob

benfaber

Bob,

What I can confirm is that you can use one of the previously mentioned input devices to get signals in through the dock connector. I don't know about connecting to the dock connector, directly, especially since the OS needs to recognize the availability of an audio input device in order to make the line inputs available to the software.

SignalScope can work with both line input channels at 48 kHz.

Ben

bone6661138

hi everyone,

i just purchased this app last night for my ipod touch 2g and immediately tested it with the Macally iVoice III and it worked wonderfully. i ran the output from the 1/8" headphone jack of my macbook applying a stereo field of sine and square wave forms (left and right respectively) to the iVoice III's stereo input and it functioned as it should. i even had my headphones connected to the touch with the speaker through function ON so that i could monitor the sound.

i would almost assume that this would work on the iphone as well.

excellent app.

bone6661138

i guess i should also mention that the iVoice III connects via the dock connector to the ipod/iphone, hence the stereo input.

http://www.macally.com/EN/Product/ArticleShow.asp?ArticleID=171

benfaber

More information regarding line level input is available here and here on the blog.