# RTA on smartphone? Good Mic desired.



## diynube (Feb 27, 2011)

The Goal: Accurate, inexpensive, and reliable RTA on the go.

Firstly, I must say that I believe the weak point in using the phone as an RTA is the Mic. If a good Mic were used I feel that the many of us with smartphones would have a very accurate and robust portable RTA. I don't really see any particular drawback to using the phone as an RTA with the exception of the Mic.

Allow me to share some of my experiences if I've piqued your interest. I have a Samsung Droid Charge. I have just been using the built-in Mic so far. My phone is only a 1GHz single core CPU. I expect dual core phones to be even better for more processing power.

I have been using the app "FFT" by Audia Sound. The app is $10.
https://market.android.com/details?id=com.audia.rta&hl=en

There are also other paid FFT apps, such as Speedy Spectrum Analyzer:
https://market.android.com/details?id=com.electronchaos.SpeedySpectrumAnalyzer

There are other FFT apps that are free such as Simple FFT:
https://market.android.com/details?id=jp.co.MusicalSoundLab&feature=search_result

In any case, I like the paid app, "FFT" by Audia Sound because I feel that it is the best for Android. This is just my opinion. From here on out, I will be referring to this app. I haven't even looked at iPhone apps. The JL Audio app isn't available on Android to my knowledge.

The "FFT" app has up to 80 points of calibration for the Mic. Because I don't have an audio reference system that is very flat, I haven't bothered calibrating the Mic. I wanted to get a decent Mic that can just plug right into the phone that doesn't have 48V phantom power. So far I've been essentially ignoring the dB levels of the frequencies.









The app allows for infinite, linear, and exponential averaging of the results. The half-life can be changed as well as the FFT depth. Decay can be shown as well as different frequency markers. The maximum frequency can be displayed.

























I have tested the the app with a frequency generator on my speaker system. I have found that the app works surprisingly well in finding the tone between 38-22050 Hz. There were just a couple low frequency areas where the app was off a couple Hz, but I would attribute that the phone's Mic. As far as I know, Android phones are limited to a sampling frequency of 44.1kHz, thus the high end of the RTA's response is 22,050Hz.

It has been fun getting RTA readings on various things: the power transformer coming into the house, my computer case, dogs barking, etc. In particular, I like setting the averaging to infinite and leave the phone sit for a while. It is also fun to change the settings so you get a very responsive reading (it can be very fast). I like seeing how high I can sing or whistle, but the sky should be the limit!

I feel like I'm so close to forgoing the need a laptop with USB audio interface for RTA.
I was going to purchase a M-Audio Mobile Pre:
M-AUDIO - MobilePre - Record Music with Your Computer
I was also going to pick up one of these 48V phantom power microphones:
Cross·Spectrum - Calibrated Dayton Audio EMM-6 Microphones for Sale

In reality, I suppose that I could splice on a 48V power supply and splice on an audio jack that would allow for plugging this Dayton Mic into the phone, but I would like to pursue a more convenient solution.
I just emailed Audia Sound to see if they have any suggestions for a microphone.

If you guys have any thoughts or criticisms, I'd like to hear them. I think we're on to something!


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## Blue Angel (Feb 21, 2012)

Subscribing...

I have an iPhone 3GS, but hoping that some knowledge transfer will take place! I have a few free RTA apps (Etani RTA, JL Audio, iAnalyzerLite and RTA Lite), but I don't trust results with any of them using the internal mic. Also, the iPhone mic is chopped off at about 200Hz so it's pretty much useless for bass frequencies.

What would be spectacular is if Dayton (or anyone who sells a quality mic setup) would release an App specific to their gear. Ah, yes... this would then cripple their profit margins ($50 mic with expensive software).

It will happen sooner or later, I just wonder who will be the first and how much will they charge for the app? Likely the best solution would be for an independent group to do it based on an existing and reasonably priced mic. Wait and see.


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## HondAudio (Oct 19, 2006)

I wish someone would write an RTA app for Blackberry OS7 :blush:


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## audionublet (Jun 9, 2009)

Blue Angel said:


> Subscribing...
> 
> I have an iPhone 3GS, but hoping that some knowledge transfer will take place! I have a few free RTA apps (Etani RTA, JL Audio, iAnalyzerLite and RTA Lite), but I don't trust results with any of them using the internal mic. Also, the iPhone mic is chopped off at about 200Hz so it's pretty much useless for bass frequencies.
> 
> ...


Studio Six Digital (makers of the JL app) have had this for years and are already on their second version of their original hardware. IMO, the Studio Six Digital apps are second to none for IOS devices. The hardware is kinda pricey ($300-ish?), but I know people who have done side by side tests with it vs a $3000 Audio Control piece and yielded the same results.

Studio Six Digital


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## omegaslast (Nov 4, 2010)

Good mic needs phantom power, good mic needs to be calibrated to a reference mic, good mic needs a flat sound card to do 20-20000hz. 

None of this is very conceivable with smart phones. I will bump my guide.. i dont see why car audio people are so afraid of doing an REW setup.


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## Blue Angel (Feb 21, 2012)

audionublet said:


> Studio Six Digital (makers of the JL app) have had this for years...


Thanks! I'll check them out!


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## igrzelczyk (Dec 10, 2009)

Blue Angel said:


> Subscribing...
> 
> I have an iPhone 3GS, but hoping that some knowledge transfer will take place! I have a few free RTA apps (Etani RTA, JL Audio, iAnalyzerLite and RTA Lite), but I don't trust results with any of them using the internal mic. Also, the iPhone mic is chopped off at about 200Hz so it's pretty much useless for bass frequencies.
> 
> ...


Thus, below 200 Hz in the car do not make preczyjnego measurement, even clio 10 can not catch it because of the reflections ... Sorry for poor English ...
I greet


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## igrzelczyk (Dec 10, 2009)

Blue Angel said:


> Subscribing...
> 
> I have an iPhone 3GS, but hoping that some knowledge transfer will take place! I have a few free RTA apps (Etani RTA, JL Audio, iAnalyzerLite and RTA Lite), but I don't trust results with any of them using the internal mic. Also, the iPhone mic is chopped off at about 200Hz so it's pretty much useless for bass frequencies.
> 
> ...


Thus, below 200 Hz in the car did not make a precise measurement, even clio 10 can not catch it because of the reflections ... Sorry for poor English ...
I greet


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## igrzelczyk (Dec 10, 2009)

Thus, below 200 Hz in the car did not make a precise measurement, even clio 10 can not catch it because of the reflections ... Sorry for poor English ...
I greet


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## minbari (Mar 3, 2011)

omegaslast said:


> Good mic needs phantom power, good mic needs to be calibrated to a reference mic, good mic needs a flat sound card to do 20-20000hz.
> 
> None of this is very conceivable with smart phones. I will bump my guide.. i dont see why car audio people are so afraid of doing an REW setup.


x2

get a mic buddy with phantom power and a ber ECM8000 or the Dayton eqiv and a copy of true RTA and you can turn your laptop into an very nice RTA for only $100.


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## audionublet (Jun 9, 2009)

Oh, and did I mention ... the hardware for the Studio Six Digital IOS app ... is made by Audiocontrol. It's about as accurate as you can get.

Apple iOS Digital Preamp / Interface


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## omegaslast (Nov 4, 2010)

audionublet said:


> Oh, and did I mention ... the hardware for the Studio Six Digital IOS app ... is made by Audiocontrol. It's about as accurate as you can get.
> 
> Apple iOS Digital Preamp / Interface


$400 with no mic?!

you could buy a netbook and an audio interface for that much. REW looks a lot more powerful than studio six digital IOS app as well

if im looking at this right the studio six app does a whopping 1/3 octaves RTA... that blows

AudioTools | Studio Six Digital


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## audionublet (Jun 9, 2009)

omegaslast said:


> $400 with no mic?!
> 
> you could buy a netbook and an audio interface for that much. REW looks a lot more powerful than studio six digital IOS app as well
> 
> ...


To each his own. The OP is looking for exactly what I showed him. The software and hardware are both good quality. They have much more than an RTA available. Did I claim it to be the best of all time? nope, but it is good. Just pointing someone in the direction they're looking for.


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## Lars Ulriched (Oct 31, 2009)

subscribed...


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## diynube (Feb 27, 2011)

Thanks for the enlightening info guys. I didn't even realize that gear existed for the iPhone. I use some AudioControl stuff and I definitely like it. As an Android fan, I will probably pursue a proper RoomEQ Wizard setup and not succumb to the iPhone  

I've been lurking the Home Theater Shack forums for some time about REW but a DIYMA member posted a link to this guide:
http://www.diymobileaudio.com/forum...-eq-wizard-setup-guide-anyone-can-follow.html

For a proper RTA I think its time for me to step up the plate and do REW. 

I still may try to find a mic that is an improvement over the built-in mic my phone uses so I can carry it around in my pocket. It would be nice to have reasonably non-crappy RTA on-the-go for curious folks like me. I like to look at RTA for things like nature sounds when I'm hiking or biking around. I really enjoy having RTA ready to go at any time. I find sound fascinating, and I keep finding myself busting out my phone to RTA stuff.

Any thoughts on this? I wonder how much money it takes before some improvement would be seen on the phone's mic. If it's much more than $50, I'll probably end up passing on this idea. I would be willing to splice on a proper TRS connector. I don't really want to do phantom power because I don't want the complexity or weight (I've entertained the idea of five 9-volt batteries in series in a little case to provide phantom power.)

Because I will likely get an REW setup anyway, I am not overly concerned about pristine mic quality-- I would just like mobile RTA that's improved over the phone's built in mic.
My phone uses this audio hub:
Audio Hubs | WM8994 | Wolfson Microelectronics
The headphone amp and DAC in this audio hub sounds surprising good when I install Voodoo Sound on the phone. It's also cool because it theoretically has bit-perfect playback using my WAV files ripped from CD.

Now that I've largely abandoned the idea of using my phone for RTA in the car, I feel like I've probably gotten outside the scope of this forum regarding microphones and cellphones. 
In any case, I'm all ears if anybody knows of any inexpensive mics that don't need phantom power and don't totally suck.
Audia Sound replied to my email that they don't have any particular recommendations.


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## HondAudio (Oct 19, 2006)

omegaslast said:


> $400 with no mic?!
> 
> you could buy a netbook and an audio interface for that much. REW looks a lot more powerful than studio six digital IOS app as well
> 
> ...


That stuff looks great, but their new iAudioInterface2 won't work with my iPod touch 2nd generation, and the original unit is sold out 

EDIT: I see that Audiocontrol will be selling "factory refurbished" units of the first model. Does anybody know how much they'll cost?


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## jeepguy_1980 (Dec 3, 2011)

I have no idea what I'm doing, yet. I want to get a 3sixty.3 and set up an REW. Right now I just have a factory HU, HD900.5, sub, and speakers. You can plug in most USB devices in an Android phone, but I think the PC option will be better and cheaper.

For now, I just got a couple of apps to play with and try to learn something about this process. This is what my car looks like right now.


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## 14642 (May 19, 2008)

audionublet said:


> Studio Six Digital (makers of the JL app) have had this for years and are already on their second version of their original hardware. IMO, the Studio Six Digital apps are second to none for IOS devices. The hardware is kinda pricey ($300-ish?), but I know people who have done side by side tests with it vs a $3000 Audio Control piece and yielded the same results.
> 
> Studio Six Digital


Wow. That's damn cool. Makes me want to get an iPhone.


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## Thumper26 (Sep 23, 2005)

Quick google search found below. It says for iPhone and iPad, but it's also made by tascam. It uses the headphone mic jack though, so I don't know why it wouldn't work with android. I may have to pick one of these up:

TASCAM iXZ Mic / Instrument input for iPhone, iPad or iPod Touch:Amazon:Musical Instruments


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## Thumper26 (Sep 23, 2005)

I googled "phantom power microphone for android" to find that. I also found this, which would work great with a regulated power supply:

Behringer PS400 Ultra-Compact Phantom Power Supply:Amazon:Musical Instruments


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## Thumper26 (Sep 23, 2005)

Frequency response may be a touch weak, but there's also this: 

Zoom H1 Handy Portable Digital Recorder:Amazon:Musical Instruments

Review: 
Gear: Zoom H1, Handy(er) Recorder. - Blog - Wolfe (with an e)


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## rich20730 (Feb 13, 2012)

Here's my portable setup:










1. iPhone/iPad

2. Audio Tools from Studio Six Digital

3. iPhone/iPad Camera connection kit

4. ART Dual Pre USB Interface

5. Dayton Audio EMM-6 Measurement Microphone

The camera connection kit allows you to connect a USB interface to the iPad/iPhone dock connector. The ART Dual Pre takes one 9v battery and provides phantom power for two XLR mics. The Studio Six apps are awesome. It's true the RTA app only does 1/3 octave, but the Smaart Tools app does 1/6 octave and the FFT does 1/24 octave.


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## CZ Eddie (Feb 26, 2012)

Does anyone know how to use FFT for Android?

I bought it a couple years ago and am just now wanting to use it.
I am only familiar with REW on my computer. And what I want is similar to that.
I need it to output a tone that goes across the entire audio spectrum. Or at least from 30hz to 4khz. And then display a chart of what levels my speaker played at for each frequency.

Can't seem to figure out how to make FFT generate a tone like REW did.
And can't find any tutorials for this app anywhere?


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## jel847 (Nov 8, 2007)

I have one of the audio control mics for iOS if anyone is interested
iOS Direct


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## AAAAAAA (Oct 5, 2007)

Since RTAing a system is nice but not the end all be all... I have found the phone setup to be pretty damn handy. I don't know how much more ot gain there is from being really precise in a car with many seats. Probably nothing to gain.

I have the mike with phatom power and true rta and they both end up being pretty similar imo.

OF course I am using a nokia 1020...the newer nokias have awesome mics in them.


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## CZ Eddie (Feb 26, 2012)

Btw, here is the Parts Express $15 mic for both Android and iOS:

Dayton Audio iMM-6 iDevice Calibrated Microphone  | 390-810


I guess I probably should have posted the below question in a new thread.


CZ Eddie said:


> Does anyone know how to use FFT for Android?
> 
> I bought it a couple years ago and am just now wanting to use it.
> I am only familiar with REW on my computer. And what I want is similar to that.
> ...


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## diynube (Feb 27, 2011)

CZ Eddie said:


> Btw, here is the Parts Express $15 mic for both Android and iOS:
> 
> Dayton Audio iMM-6 iDevice Calibrated Microphone* | 390-810
> 
> ...


I recently got this mic. With the app, Audio Tool, I can load the mic's included calibration profile. Then I have what is in theory an accurate measurement mic. I gotta say, it sure is nice to have a mic that small. 
I don't believe those FFT apps can load the calibration file though . Audio Tool was the only app that I could find that could. 

Sent from my SM-N900V using Tapatalk 2


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## Patrick Bateman (Sep 11, 2006)

The mics on phones really aren't that bad. I've found that the results I get with the RTA on my iPhone, Nexus 4, Nexus 5 and iPad are all very close to what I get with my laptop and the Dayton mic.

The main difference I notice is that the results from my phone are useless below about 100hz. I've seen some forum posts that indicate that the operating system itself inserts a high pass filter on the microphone input. This would make sense, because by doing that, they filter out rumble that you might get if you were talking on your phone while walking down the street, or driving in a car. Seems reasonable.

But between 100hz to about 16khz, my phones appear quite accurate.

The main reason that I continue to use a laptop for any serious measurement is that my phone can't do gated measurements. But the quality of the RTA results? Very good.


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## CZ Eddie (Feb 26, 2012)

Do you guys know of ANY Android apps that will generate a sine wave from 20hz to 20khz and show me a plot of my external speakers response?

Like what REW does?


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## SPLEclipse (Aug 17, 2012)

CZ Eddie said:


> Do you guys know of ANY Android apps that will generate a sine wave from 20hz to 20khz and show me a plot of my external speakers response?
> 
> Like what REW does?


Upon a (very) quick glance, it looks like Audiotool will self generate tones for measurement:

https://play.google.com/store/apps/details?id=com.julian.apps.AudioTool&hl=en

However if you just want FR, you can use pink noise.


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## CZ Eddie (Feb 26, 2012)

That's the only one I haven't tried yet. Don't want to spend $8 on something that may not work. And the ridiculous 15 minute refund policy from Google is just not enough time to figure out how to use an app, or if it won't do what you want it to. Ugh.


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## HondAudio (Oct 19, 2006)

Where are the RTA apps for Blackberry? ;[


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## REGULARCAB (Sep 26, 2013)

HondAudio said:


> Where are the RTA apps for Blackberry? ;[


They got left back in 2005 :laugh:


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## bsa77 (Aug 12, 2013)

While talking about AudioTool and calibration and mics and such, dont know if it's been mentioned somewhere before, but there is a method provided for calibrating your device.
It will calibrate your device mic, add it together with your imm6 calibration file and then you load it into Audiotool. If i got that right, haven't gotten around to test it myself yet


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## AAAAAAA (Oct 5, 2007)

For 
window phone 8

signal generator by HSE
and 
spectrum analyser by golden pot


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## CZ Eddie (Feb 26, 2012)

SPLEclipse said:


> Upon a (very) quick glance, it looks like Audiotool will self generate tones for measurement:
> 
> https://play.google.com/store/apps/details?id=com.julian.apps.AudioTool&hl=en
> 
> However if you just want FR, you can use pink noise.


The app developer responded to my email and says the app can indeed do sweeps. And even pointed me to an online manual that I wasn't able to find on my own:

https://sites.google.com/site/bofinit/audiotool#TOC-Sweeps


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## boom_squid_2 (Jan 29, 2008)

HondAudio said:


> Where are the RTA apps for Blackberry? ;[



Can't you side load the android versions?


Sent from my iPhone using faith


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