iPhone 4 Audio and Frequency Response Limitations
The iPad’s lack of line level audio input support via the dock connector certainly raised the question of what would be in store for the iPhone 4. Now that I have my hands on the new iPhone, I thought I would go ahead and report on the state of audio I/O on the new device.
Here’s what seems pretty clear, based on my initial tests of the iPhone 4:
- The iPhone 4 does not accept standard iPod accessories with line level input
- Unfortunately, the new iPhone doesn’t work with the USB connector of the iPad camera connection kit, either, so there really isn’t a two-channel audio input option at the present time.
- The frequency response of the iPhone 4’s headset mic input is virtually identical to that of the iPhone 3GS.
- The built-in microphone’s frequency response also closely matches that of the 3GS.
iPhone 4 Headset Input Frequency Response
iPhone 4 Built-in Microphone Frequency Response
It really is unfortunate that there is currently no way to get stereo signals into the new iPhone 4, although I’m confident that it’s only a matter of time before an acceptable solution presents itself. Beyond this glaring limitation, the iPhone 4 is essentially the same as the iPhone 3GS (and iPad) in terms of its audio performance. It will be interesting to see, though, what new possibilities open up with the A4 processor, the increased memory, and the high-resolution display (which is quite amazing, by the way).
Thanks for this early review. I was on my way to get my preordered iPhone 4 and now I’m going to let it go. I use the iPhone 3GS as a recording tool with a the Belkin stereo external mic (with a surprisingly good quality) and I can’t loose that option. I know the Blue Mikey doesn’t work either on the iPhone 4, but have you tried any other external microphones? I can not believe they closed the door for the iPhone as the perfect recording and editing tool for journalists and others. Thanks.
It is a shame, but I know that the likes of Sonoma Wire Works are looking at an interface for the iPad and iPhone 4 pinouts. No clues on timescales as yet though.
I can confirm that the Alesis ProTrack DOES NOT work with the iPhone 4!?!
Now I need to find a new solution for stereo line-in
Per SonomaWorks site, their new device with also NOT work with the iPhone 4
That’s right. As I mentioned in the article, there is no line input solution for the iPhone 4 at the moment.
Ben – have you tried the Griffin iMic connected via the official IPhone 4 Dock (you mention above you tried using the iPad Connection Kit, perhaps the new iPhone 4 Only Dock will work – Apple’s site mentions it should work with iPad audio AV cable accessories, so it sounds like it might be a possible solution). I have not tried this yet as I have neither the iPhone 4 Dock (ordered) nor the Griffin iMic (tempted to buy to try)
iPhone 4 Only Dock:
http://store.apple.com/us/product/MC596ZM/A
The iPhone 4 Dock does not provide a USB port–it’s basically just an extension of the iPhone 4’s dock connector that also happens to hold the iPhone upright. Also, the AV adapters work for AV output only.
I realize the iPads USB connector is not officially supported by the iPhone 4 but has anyone tried it?
As indicated in the article, the iPad USB connector (from the camera connection kit) does not work with iPhone 4, or any other iOS device that currently runs iOS 4. (I have tried it out.)
I recently posted on audio input for the iPhone 4 (…), and have just discovered that the adapters on sale at KV Connection don’t accept a standard XLR mic-level mic at all… (haven’t tested with other sources yet) it seems the iPhone headset sends some sort of signal to the camera app that switches the app’s audio input to that mic instead of the iPhone’s built in mic…
Do you know any way around this limitation? It would seem trivial to get audio in through the mono mic port…
Please see this post.
So I really only need a mono signal into my iPhone 4 when I use it as a sound level meter. I had been using an Alesis ProTrack. However, no matter what I do I can’t seem to get it to recognize our measurement mic plugged into the ProTrack. Is this what @bbqgrass meant… the ProTrack literally does not work at all with the new iPhone 4? BTW, the graphics for SignalScopePro look great on the iPhone 4!
As indicated in the article, the iPhone 4 does not accept line level input. This means that existing iPod accessories that access line level input through the dock connector will not work with the iPhone 4. This includes the Alesis ProTrack. So, even though I said that it’s too bad that no stereo input solution exists, it remains that no good mono line level input solution exists, either.
Comparing my 3GS to my iPhone 4, I’ve found that the 3GS input levels are significantly higher than the iPhone 4. Tests with the top and bottom mic on the iPhone 4 and with the external mic all show significantly lower levels than with the 3GS. I don’t know if this is by design or if my sample of the iPhone 4 is at fault. The Recorder app hardly indicates a recording level on my iPhone 4 where the needle bounces normally on the 3GS. I see the same effect comparing Dragon Dictation on the two phones. The impact has been that speech recognition on the iPhone 4 using iOS or Google Mobile is significantly worse on the iPhone 4 unless I speak at unusually loud levels.
Has anyone else observed this or is my iPhone 4 behaving differently than yours?
It would be great if audio folks filed feature requests at https://bugreport.apple.com/ to get a some control over the high pass filter and to get stereo line in back into the dock port on a future device.
The more the merrier and Apple does pay attention to that uses it to prioritize things.
Do you guys know if alesis pro track works on IOS 4. I have a iphone 3GS though.
Kind Regards,
Rui
The ProTrack works fine with iOS 4. It does not work with the iPhone 4.
Do we know yet whether the iPod Touch 4th Generation has similar dock I/O limitations to the iPhone 4?
It’s a pretty safe assumption that the dock I/O on the new iPod touch will be similar to that of the iPhone 4.
When you hook up an iPad connection kit to an iPad, the USB port allows usb audio in (and out).
Anyone try hooking up another dongle – adapter that has a USB port to the iPad, and test it with USB audio? IE: Is there something ‘special’ in the Camera Kit that enables USB audio?
Analog line in on the iPhone was ok while it lasted, but it was basically impossible to stop interference sounds, like the cell phone rattle, etc.
USB audio support would be great, especially if there was a way to do it with a wire that looks like a standard apple 30 pin connector. (the other end should be a female USB or even mini USB).
Also I wonder if iOS 4.2 – when the iPad and iPhone are running the same OS will make the camera connection work? The hardware on the iPad and iPhone are so similar…
Yes, there is. The iPad Camera Connection Kit is still the only thing that enables USB audio I/O on the iPad.
The $50 Azden ECZ-990 Directional Mono Microphone is the perfect external mic for the iPhone 4. http://www.amazon.com/AZDEN-ECZ-990-Cardioid-Camcorder-Microphone/dp/B00006JPD9
It’s the best bang for the buck in a $50 iPhone 4 external mic. As with almost anything, you get what you pay for. The notes below in the specs compare the $50 ECZ-990 to the $250 Rode NTG-2 mic.
Many 3.5mm mics, such as those from Vericorder, do not work with the iPhone 4 because of an impedance mismatch.
The ECZ-990 along with a 3.5mm TRRS connector from KV Connection works fine with the iPhone 4. http://www.kvconnection.com/product-p/km-iphone-2trs.htm
The Azden box says: “ECZ-990 Zoom Microphone For Camcorders” They should redo their box and say: “ECZ-990 Directional Microphone For Camcorders & The iPhone 4”. The word “Zoom” in this case means “Directional” or “Narrow Polar Pattern” when speaking about microphone pickup pattern types.
The iPhone 4 shoots HD 720P Video. However, using the iPhone 4’s pinhole internal Omni Directional Short Range Mic is a poor choice when shooting HD Quality Video. The iPhone 4 internal mic is best for phone call usage … not video / movie usage.
Good quality audio is at least 50% of the equation when using the iPhone 4 in the movie mode. This is specially so for journalists who are incresingly using the iPhone 4 for their MOJO Kit – Mobile Journalist Camera / Video Kit when they don’t have their DSLR or video camera with them.
In breaking news situations … the best camera / mic is the one you have with you! The iPhone 4 & ECZ-990 is the perfect duo to have with you.
An increasing number of “Citizen Journalists” are also using their smartphones, such as the iPhone 4, for breaking news events and forwading their video and audio on to news souces such as CNN’s iReport or posting it themselves on YOUTUBE. Apps such as iMovie can be used on the iPhone 4 for a quick edit.
For better quality HD Audio on the iPhone 4, an external microphone such as the the Azden ECZ-990 is the best way to go. It’s easy to carry with its 6 inch length and low weight of 2.75 ounces. The iPhone 4 weighs 5 ounces. So together, you have a 7.75 ounce audio and video mobile kit.
The ECZ-990 can be used as a handheld mic for interviews (get a 15ft to 25ft extensiion cable)or mounted next to the iPhone 4 (in a holder with 1/4″ thread)on a 11 ounce Zipshot collapsable tripod. http://www.amazon.com/Tamrac-ZipShot-Compact-Ultra-Light-Instant/dp/B002WC8862
Azden ECZ-990 Specs & (Notes For iPhone 4 Users and what the specs mean)
A. Mic Type / Transducer Type: Electret Condenser (For the iPhone 4, a “highly sensitive” condenser style mic is preferred over a lower sensitive dynamic mic. Some iPhone 4 users have tried a 350 Ohm dynamic mic (XLR connection) with the iPhone 4 along with a special matching transformer. However, most iPhone 4 users, such as journalists, are choosing a condenser mic such as the Azden ECZ-990. The $250 Rode NTG-2 is also a condenser mic … but with a XLR connector.)
B. Polar Pattern: The ECZ-990 has a switch to select 2 different polar patterns. 1. In the the Long Supercardioid “Directional” Pattern the ECZ-990 has a “Zoom / Directional” 30 foot range and picks up sound directly in front where it is pointed. 2. In the Short Cardiod Pattern the ECZ-990 picks up sound from a wider set of directions. For the iPhone 4, the Long “Zoom / Directional” pattern is the best. You direct or point the iPhone 4 video camera … you direct or point the Azden ECZ-990 mic in the Long “Zoom / Directional” position toward the sound source. The Rode NTG-2 has a wider Supercardioid pattern than the ECZ-990.)
C. Frequency Response Range: 150Hz – 18000Hz (This range is perfect for the iPhone 4 since the iPhone 4 has a low pass cut off filter of 150Hz for the internal mic and external mics. The human voice frequency band ranges from approximately 150 Hz to 3400 Hz. The ECZ-990 will also pickup various musical instruments and sounds which are are in the higher frequencies. The Rode NTG-2 mic has a 20Hz – 20,000 frequency response range. The iPhone 4 frequency range is 150Hz to 20,000Hz)
D. Microphone Output Impedance: Long = 1700 Ohms (at 1000Hz) and Short = 760 Ohms (at 1000Hz) (It is very important to note that the iPhone 4 internal mic input requires a mic with an impedance of 800 Ohms and higher. The ECZ-990 has a 2 position switch: Long & Narrow Directional Pickup Pattern at 1700 Ohms and Short & Wide Pickup Omni Directional Pattern at 760 Ohms. It is recommended that iPhone 4 users select “only” the Long & Narrow position for optimal audio perfornance and compatability with the iPhone 4. The Rode NTG-2 Mic has a 350 Ohm Output Imbedance and can only be used with the iPhone 4 with a Impedance Matching Transformer. Hosa Line Match Xformr 3.5MM M/xlrf)
E. Sensitivity: Long & Narrow = -33dB (at 1000Hz 1V/Pa) and Short & Wide = -43dB (at 1000Hz 1V/Pa) (As noted above, iPhone 4 users should select the Long & Narrow Directional position. Mic Sensitivity indicates how efficiently the microphone converts acoustic sound pressure to output voltage which goes into the audio amplifier in the iPhone 4. A high sensitivity microphone creates more voltage and so it needs less amplification at the recording / pickup device such as the iPhone 4. The -33dB Long & Narrow Directional setting is more sensitive / efficient than the -43dB Short & Wide Omni Directional position. The $50 Azden ECZ-990 at -33dB is more sensitive than a $250 Rode NTG-2 XLR condenser mic at -36dB)
F. Maximum Input SPL – Sound Pressure level: 100dB (The point where the mic distorts, or clips the waveform. [More=better] In normal interview situations with the ECZ-990 with the iPhone 4, a SPL of 100 dB is fine. The higher the Maximum SPL value, the better, although microphones with a very high maximum SPL also have a higher self-noise. The Rode NTG-2 has a Maximum SPL of 131dB)
G. Dynamic Range (Typical): > 75dB (The point where the mic distorts, or clips the waveform. [More=better] If stated on its own, for example “120 dB”, it conveys significantly less information than having the self-noise and maximum SPL figures individually. The Rode NTG-2 has a dynamic range of 113dB.)
H. Signal-to-Noise Ratio: > 43dB (Signal to Noise ratio = The range between self noise and a reference signal. [More=better] The Rode NTG-2 mic has a Signal-to-Noise Ratio of 76dB.)
I. Microphone Output Connector: 3.5mm TRS Male Plug (The iPhone 4 requires a special $20 KV Connection part: KM-IPHONE-2TRS. Just Google “KM-IPHONE-2TRS” and you will find it. This connector has a 3.5mm Male TRRS Plug which goes into the iPhone 4 and the other end a Female TRS connector into which the Azden ECZ-990 plugs into. There is also a headphone TRS jack which works in the playback mode only. No external mics will work on the iPhone 4 without this special TRRS connector!)
J. Power Requirements: 1.5 Volt AAA Battery (The ECZ-990 has an ON/OFF switch. It is recommended that that iPhone 4 users select a longer life 1.5 Volt lithium battery.)
K. Dimensions & Weight: 6″ Length x 0.83″ Diameter. Weight 2.76 oz Without Battery (This compact mic size and weight means the ECZ-990 can readily be carried along with the iPhone 4.)
Will the AZDEN ECZ 990 mic work on the iphone 3gs?
Hey guys,
Thanks for posting this up! I’ve been looking for an external mic that’s compatible with the iPhone 4. I came across a site that suggested VeriCoder MiniMic, but then found out that it’s not supposed to work with the iPhone 4.
Well, I decided to try it anyway. They’re available at London Drugs stores in Canada, so I just went and picked one up. First test, the mic would cut in and out… boo.
It turns out the issue is the impedance difference. I used to be an electronics tech in a past life, so I decided to mod the mic. I simply added a 1.5k resistor in parallel (basically, solder the leads to the two leads coming into the mic) and booya… it works like a charm 🙂
Thought I’d share the findings.
Vericorder just came out with a modified Mini Mic – Video for the iPhone 4 US$25 See Website. It’s an Omni Dynamic Mic (1/8″ male jack)at 2200 Ohms.
So … no more impedance mismatch issues. However, it has a much higher in ternal noise level than the Rode NTG 2 Shotgun Condenser Mic (XLR & Battery Powered) … you will need a KV Connector adapter.
Of course, these mics will still be subject to the effects of the high pass filter that the iPhone 4 applies to its headset input.
Hi,
I got the kvconnection line in adapter.
I want to record a video of a band, with the audio signal
From the mixing console. Works very good but the it seems
That the iphone cuts the bass at about 150-200 hz
Does anybody know if it is possible to turn off this lowcut?
Thanks
Flo
hello,
I wanted to chime in with research that I found useful.. I also purchased the kvconnection line in adapter and had similar results with my iphone 4 cutting out the low frequency bass, has anybody found a fix for this yet?
I also tested the cable with my 3gs getting same results but THEN tested the cable with my old 3G which does NOT have the new 4.os (multitasking)running.. this resulted in PERFECT stereo recording from my mixing console direct to my phone..so my question is does the 3gs or i4 have a software update that is causing this low frequency cut out, or is the old 3g the last version of iphone that allows stereo input recording?
According to my findings, the hardware schematic arround the Cirrus Logic 338S0589 CODEC is responsible of the Hipass filtering of the mic input.
This high pass flter is simply made with 1µF ceramic capacitors in serial with the two differential Codec MIC inputs of the chip.
To correct this filter frequency response (lower it by ten factor ) it would require to add two 10µF ceramics capacitors in parallel with the original (1µF) one.
Hope this helps
John
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-3 dB is half power, not half amplitude (or “volume”). The roll-off applies to the input, not the output, so these plots do not suggest that there is any problem with the output frequency response (which is actually quite flat across the audio band).
Hi Ben
Thank you so much for all the great work you’ve done across all these posts. I have a new iphone 4 and was immediately sucked in to the audio possibilities particualrly with the 4 track apps. Like most I intially thought a simple breakout cable would do the trick for line/mic input. Reading your posts I quickly realised the dock connector is the only way to go for quality audio. I got carried away an bought a macally ivoice for £20, only when it didn’t work did I see this thread. I’m so gutted, still at least I didn’t buy a protrack.
People who are pushing made for iphone mics for recording have no idea. I would have used the macally with 1-2 C1000s (battery powered with balanced XLR to minijack adaptors) or SM57s for close mic’ing. If I had phantom power e.g. protrack I could use my Neumann TLM103. No iphone mic will come anywhere near that kind of quality.
Keep the good work and let us know when someone makes a device that will do the job so I can have the mobile studio I’ve always dreamed of.
Any news about the stereo thing on the iPhone 4? Im buying it, but id like using it as a stereo field recorder…
Great info in here anyway.
Hi – Interesting reading, but I’ve recently realised that (and this would need to be confirmed) having listened to song recordings I made on my iPhone 3gs compared to recordings made on my iPhone 4 (all in ‘Voice Memos’ using the mic on the phones) the recordings from the 3gs seem to be at 80kbit/s but the recordings from the iPhone 4 seem to be only 64kbits/s…..
Hi there,I’ve been reading about the iPhone 4’s lack of Stereo recording options with increasing dismay.
It’s really good that sites -such as yours in particular-are offering advice and tips etc. What a shame that Apple have changed the way the phone accepts audio-one can only wonder why!
I’m an old(ish)geezer who thought “I might have a bit f fun with the music recording apps on iphone4,I hadn’t given much thought to all the other recording scenarios people might require-Journalism,Video etc. I’d be so annoyed if I’d purchased a new phone specifically for say Video recording only to find that even with an assortment of cables and/or other devices I was unable to record in Stereo-this is the 21st century after all!
So..what to do. Should I get the new “iRigMic”&vocal app?-will it record anything other than vocals without sounding “tinny”-Somehow I doubt it! Or maybe I’m s’posed to wait for the iphone5,where -maybe?-Apple will have rectified the situation. I started my “quest”knowing nothing of Mics or impedance or whatever-I’ll be an
expert on the subject soon!-Thanx 4good research,2 questions-do “Dock”type audio out devices give a TRUE
Line-Out signal as opposed to connecting phone to Hi-Fi via headphone socket? And,do you-or anyone!-know if the “iRigMic” is a good option for use with compatible recording apps-or just another “silly” gadget!
Thanks again for all the info on your site &for any advice you can give me with regards to my “2”questions
Mik_iD. 🙂
Mik.i
Thanks for this page. After mulling over this situation and reading what little there is to find on the subject, here are some of my thoughts on why a stereo line input is going to take a while on the iPhone 4, iPT-4G, and future devices if wired the same. I suspect these newer iModels accept class-compliant USB audio, as it is on the iPad (the hardware is not an obstacle).
1. Any device that would work with USB audio would have to provide it’s own power on these portable models but it would just suck the life out of the battery and shorten its useful life. With 4.3, Apple reduced available USB power on the iPad to 20ma from 100ma, making a lot of devices now require a powered USB hub for them to work. Clearly this would be even more of a problem on the smaller portable devices with smaller batteries.
2. Any device providing class-compliant USB audio would definitely be more complex, expensive, and require more power than just a line-level feedthrough or simple ECM mic circuitry. It’s a challenge most companies seem to be having a hard time taking up as none of them (Blue, Belkin, etc…) have come up with any alternatives since these models launched 6 months ago. However cheap USB audio devices do exists, so I don’t think this is a real issue.
3. The possibility always exists that the absence of this option on these models is a strategic move for Apple: maybe they simply want to encourage folks to buy iPads making usb audio a value-added incentive; or maybe they plan on releasing their own hardware for this; or maybe they don’t even know, but it’s a an option they can keep open by denying us the possibility while holding out on the technology.
All we can really do is wait and see. Or become 3rd party Apple hardware developers.
So frustrating! I am one of the people that purchased an iPhone 4 with the express intent of using it as a field recorder (with a Mikey or similar).
Thanks a bunch apple, and I can only imagine that the makers of Mikey etc feel the same. I’m surprised about how little there is regarding this on the internet. Boo-urns!
Hi everybody,
I am also in the same boat. As in waiting for some developer to come up with a good stereo solution.
Anyway, I saw a link to this a while back. Just waiting with baited breath for apogee to make an announcement…
http://www.apogeedigital.com/products/mic.php
Looks like some stereo options for the iPhone 4 are under development. Sonoma Wire works had a prototype Guitar-Jack at this year’s NAMM, also Fostex is due to release the AR-4i sometime midyear…
I’m very sad to be repeating my search for a decent audio-recording solution on the iPhone 4, months later, only to find that there is still no solution. I thought for sure it would just take accessory makers some time to retool their products to changes in the new hardware, but it’s now looking like this is a cold trail. I had hoped for full USB-compliant audio, like with the iPad, but I’d be more than happy with a simple stereo line-in at this point.
One last thing: I’ve seen plenty of talk about the camera connection kit not working with the iPhone 4, but HAS ANYONE ACTUALLY TRIED IT with iOS 4.3 on an iPhone 4??
Sonoma WireWorks is now selling their Guitar Jack dock-slot audio connector for iPhone 4. Spec looks good. I’ll soon see.
Good news everyone:
AudioControl Industrial is now selling Studio Six Digital’s iAudioInterface 2 iOS Digital Preamp that has an A/D inside it and connects to the iPhone 4. It’s an external box, but none-the-less does get high quality audio into the iPhone. Oh, and it’s $399 haha.
Enjoy,
Todd
Does the fact that the Magnitude is nearly flat mean that at 20khz the iPhone mic can accept a very low range of magnitude?
I am using a Tascam IM2 stereo dock mic. it works really well for recording. I haven’t done any frequency response testing with it however. I don’t think I have the gear to do such a thing specifically around a flat transducer to output the test sweep. But it works with the iphone 4 and SignalScope.
Hello –
Looking at the frequency response of the iPhone inputs I think that it is not so far away from A-weighting: -30 dB @ 50 Hz, even if the attenuation between 100 and 500 Hez is not correct.
So would it be possible to use a modified A-weighting that takes into account the frequency response of the input? Of course this would not help for flat or C-weighting, where an amplification of low frequencies would be needed that compensates the high-pass filter of the input.
That would mean a special version of SoundMeter for iPhone 4.
What do you think?
Best regards from Switzerland
Beat W. Hohmann
“JohnHWman
March 23, 2011 at 4:44 am · Reply
According to my findings, the hardware schematic arround the Cirrus Logic 338S0589 CODEC is responsible of the Hipass filtering of the mic input.
This high pass flter is simply made with 1µF ceramic capacitors in serial with the two differential Codec MIC inputs of the chip.
To correct this filter frequency response (lower it by ten factor ) it would require to add two 10µF ceramics capacitors in parallel with the original (1µF) one.
Hope this helps
John”
have anyone tried this? It seems to be interesting..
thanks to this thread i understand why my belkin tunetalk doesn’t work with iphone4 and ipod touch4. As mentioned above the Tascam IM2, which has a build in A/D converter, does the work. Anyone who knows what the quality of the Tascam is compared to the Belkin tunetalk (which is amizing good in my opinion) ?
I have a student doing a science project on this same topic.
He is trying to get technical information about the iphone 4 microphone.
Any suggestions on where he can get the specs??
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Thank you, you are the only one that provides this useful information unlike Apple that provides only fancy videos/sales brochures…
I needed to use the device for some photoacoustic project where area of interest would be 100Hz down, well, glad to find out the device useless for that project!
You saved me some time
zega,
The low-frequency roll-off discussed in this article hasn’t been a problem since iOS 6. You might want to read more recent articles on the blog, like this one.
Ben
I wonder why these chart have never been update to any later iphone descendant. Is this a misleading if not iphone descendant has same or better frequency response.
I am not a iphone expert, I found my ipad air2 has worse frequency response at high end than my old iphon 3 and my Samsung S3.
I don’t have solid evidence because I am not that confident of my observation. I hope someone can help me confirm my observation or show me some link that can compare the iphone 5 and 6 with iphone 3 or 4. thank you very much.