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Is there a point to use the free True RTA software? For one the web site mentions that sound card calibration is not available in free version. Second, the RTA resolution is 1 octave. I assume this means I can take a reading at say 4, 8, and 16KHz, but nothing in between which seems like very coarse. Is this enough to do some basic tuning, or should I buy version with 1/3 or 1/6 octave resolution?
 

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It wouldn't be enough to know what's really happening. Just like 16 band graphic EQ and even 31 band isn't always enough to get out some (small band) peaks.
 

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Just go ahead and pay for the better one. It isn't that expensive, plus it really helps to see problem areas if you have the means to cut that specific band. It was a necessity when I ran a DQX as there was frequencies that I didn't know was giving problems. The end result was a very balanced system that imaged well.
 

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RTA Pro Analyzer - Android

this looks cool, 5.49 for 1/12 octave slices
This is cool, I have it. I haven't tried the calibration as I don't have a reference source, but my plan is to try it with the Dayton IMM-6 once Parts Express has it back in stock. It's an omnidirectional mic calibrated for flat performance that plugs into a smartphone(iPhone, Android are mentioned).
 

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REW (Room EQ Wizard) is free and goes to 1/48th octave with mic and sound card calibration. No C-weighting unfortunately but I don't know of any of the free or reasonably priced laptop-based programs that do.
 

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can't you just play pink noise tracks?

I don't understand why you'd need a reference source, and why the internal mic isn't good enough.

I'd expect to see some variation between this app and phone combination and something the professionals use that goes for 3K a pop, but for our purposes you can see what's going on just with what you have already?

am I missing something, is the internal mic not up to a reasonable quality?
I don't know about android phones, but the iPhone internal mic has a high-pass filter starting at 250hz with a 24db/octave roll off.
 

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can't you just play pink noise tracks?

I don't understand why you'd need a reference source, and why the internal mic isn't good enough.

I'd expect to see some variation between this app and phone combination and something the professionals use that goes for 3K a pop, but for our purposes you can see what's going on just with what you have already?

am I missing something, is the internal mic not up to a reasonable quality?
The limitations are a rolling off of bass frequencies, making it useless for EQing subs. Also, the mic in the phone is directional. There's a big difference between the measurements with the mic pointed at speakers vs holding the phone so I can watch the screen.
 

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I thought people were using iPhone apps successfully for this?
I'm using the Audiotools app from Studio Six Digital for my iPhone and iPad. The app works great and has a ton of features, especially if you purchase some of the add-ons. I've been using this app with the Dayton EMM-6 and a USB interface with great results. I've used the internal mic to make quick adjustments, but hadn't used it for serious tuning because of the internal filter.

Upon further reading, with the iOS6 update, it looks like the app can now disable the internal filter:

Microphones and iOS Devices | Studio Six Digital

Previously, when you used the internal mic, the app applied an inverse filter to compensate for the low frequency roll off, but you were still only getting a rough approximation below 250hz. This also applied to mics connected to the headset jack. The only way to bypass the high-pass filter was to use an external dock mic.

I still think there's a lot of benefit to using a calibrated, omnidirectional mic for tuning, but the convenience and portability of having a small all-in-one package on your phone is pretty cool.
 

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thanks for that explanation.

I have an Audyssey mic that is omni and supposed to be fairly accurate, if you would be so kind as to determine from your experience, whether or not the accuracy of this type of mic will better the internal mic due to it's omni nature, or if the phone measures comparatively well with what you were getting out of the Dayton.
I actually have the Audyssey mic too. I have one from a Denon home theater receiver and another from the Alpine PXE-H660. I'll see if I can do a useful comparison between the internal mic, the Audyssey mic, and the EMM-6 when I get a chance. The main challenge will probably be trying to replicate the exact position and orientation of the iphone and mics for each measurement. When I tune with the EMM-6 I have it attached to a pole that I stick through the opening between the seat and the headrest and I sit in the back seat and rotate it back and forth with RTA set to average the results. It might get tricky with the iPhone.
 

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I'm using the Audiotools app from Studio Six Digital for my iPhone and iPad. The app works great and has a ton of features, especially if you purchase some of the add-ons. I've been using this app with the Dayton EMM-6 and a USB interface with great results. I've used the internal mic to make quick adjustments, but hadn't used it for serious tuning because of the internal filter.

Upon further reading, with the iOS6 update, it looks like the app can now disable the internal filter:

Microphones and iOS Devices | Studio Six Digital

Previously, when you used the internal mic, the app applied an inverse filter to compensate for the low frequency roll off, but you were still only getting a rough approximation below 250hz. This also applied to mics connected to the headset jack. The only way to bypass the high-pass filter was to use an external dock mic.

I still think there's a lot of benefit to using a calibrated, omnidirectional mic for tuning, but the convenience and portability of having a small all-in-one package on your phone is pretty cool.
+1 on the Audiotools app, I'm on Android though. It's great for quick and dirty stuff with the phone mic, with an external calibrated mic it's even better.
But, without a doubt, REW is still the software to use for detailed measurement and tuning. You can get better software, but REW's free, and there is nothing better for free, or even close to free.
 

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+1 on the Audiotools app, I'm on Android though. It's great for quick and dirty stuff with the phone mic, with an external calibrated mic it's even better.
But, without a doubt, REW is still the software to use for detailed measurement and tuning. You can get better software, but REW's free, and there is nothing better for free, or even close to free.
Is there a way to view an RTA on REW the way they look on audiotools? Much easier to make adjustments on the fly with the visual RTA on Audiotools.
 

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Is there a way to view an RTA on REW the way they look on audiotools? Much easier to make adjustments on the fly with the visual RTA on Audiotools.
Yeah, it's got an rta window, rta button at the top of the main window. It defaults to spectrum though, you need to change that to anything from 1/1 to 1/48 octave rta.
 
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