iPhone Line Input Frequency Response Comparison


Although I already listed some options for getting line-level audio into an iPhone or iPod touch, that list didn’t include much information that would suggest which option would be best. One important metric that people frequency ask about is frequency response. Well, I finally have some frequency response comparisons available to help answer that question.

These measurements were made of various dock connector devices, attached to an iPhone 3GS. As in other frequency response measurements, the audio was routed through the iPhone, with a little help from SignalScope Pro. This means that each measurement includes the frequency response of the iPhone 3GS headphone output.

The tested devices include:

Line Input Frequency Response Comparison

Line Input Frequency Response Comparison

Based on these measurements, and the unreliable nature of the iTalk Pro, I would recommend the Tunewear Stereo Sound Recorder for iPod as the Line-input device of choice. However, if you need balanced input circuitry, adjustable gain, or phantom power, then the added cost of the Alesis ProTrack may be justified.

As indicated previously, the iVoice Pro may still be the best option for the original iPod touch, depending on your needs.


  • Gianluca

    The Alesis ProTrack works with the 3GS????

    • ben

      In my experience, so far, audio accessories, like the Alesis ProTrack, behave the same with the iPhone 3GS as they do with the iPhone 3G. The ProTrack does work with the 3GS, although it has the same issue as the 3G, that is that you still need to use the iPhone’s headset jack for audio output.

  • Rod

    The link for Tunewear Stereo Sound Recorder is dead. According to Tunewear it is no longer available. I was able to buy one and, although the line input is flat, the built-in Mic response is quite poor.

  • Brian

    Have you looked at these?



    iPod Line In/Out adapters

    • ben

      Those devices are not officially approved under the Made for iPod program.

      • Francis Pressland

        where can we discuss those devices not approved by Made for iPod program,I mean come on just because its not approved does not mean it isn’t a valid thing to try out.

        I know you don’twant to get kicked off the apps store ,so just gve a hint where I might find information


        • ben

          where can we discuss those devices not approved by Made for iPod program

          You could try to discuss them in places that are geared for that.

          so just gve a hint where I might find information


  • Matt

    Any idea where one can still purchase the Tunewear device?

  • Andy Kayll

    I have just found a site (natch in Japan) that still has the Tunewear stereo in stock 🙂
    As it is in Japan you can not purchase directly as you need a Yahoo.jp address to log in but I have found a very helpful guy who will handle the transaction and shipping for a very modest fee.
    I am waiting for him to get back to me with prices but as they are small and light, if other people are after one, I could buy a few and we can split the shipping and handleing…
    Also can’t get too many or will get hit for import tax.

  • Tom Andersen

    I would really like a tunewear. Please contact me via email at tom.andersen on gmail. –Tom

  • Peter Smith

    Ditto – if the price is sensible I too would like a tunewear, cresscon@gmail,com, cheers Peter

  • Greg Ogonowski

    I would also like a TUNEWEAR, if it’s not too late to get in on this.
    Please contact me via e-mail: greg (a) indexcom.com

  • Peter

    what’s the value of the resistor between pin x and ground of all these microphones that use the line in of the dock connector ?

    • ben

      Please join the Made for iPod/Works with iPhone program to gain access to the relevant documentation.

  • aquaanna

    I want to listen to some high frquency sound therapy CDs on my iPhone. The sound therapy company said if I did this I nay lose some of the benefit of the sound quality/depth/frequency. However it is my understanding that if I download the music files as wav vs mp3 the files and therefore the effects of the sound therapy should br exactly the same. They said I needed headphones that had a high frequency range and the ones I got go from 18 – 23,000hz. If I put the wav files on my iPhone do you think it should transmit the frequencies with a broad enough frequency range to match that ov my headphones? I’m trying to find where your site lists the frequency range of the iPhone 3gs.