# Noob at tuning with RTA HELP! iMM-6



## rc10mike (Mar 27, 2008)

I have never tuned my stuff with a RTA. I dont even know the first step in doing it. I dont want to become a master SQ tuning guru nor do I have the time for it anymore. I mosty did it by ear and whatever sounded good to me.

My new car however, is going to have issues simply because of its design and my hard-headed nature to want to keep the car as stock looking as possible. So I invested in this:
Dayton Audio iMM-6 Calibrated Measurement Microphone for Tablets iPhone iPad and Android

I do not care if my system will win every SQ competition, I just want something to get me in the ballpark.

I am also aware that the hardware of the phone can also affect the freq. response, but I do not care at this point in my life, thats too much to worry about.

Back to the main point, how is it done?

Turn your mic on, play a sine sweep, then EQ from there?! Is that basically it?


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## SkizeR (Apr 19, 2011)

except do it with your phone and an rta app..


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## XSIV SPL (Jun 24, 2014)

Some tune with RTA, and some tune by ear... some use a combination of both...

I don't know specifically what you're trying to accomplish, but many folks don't use RTA when tuning...


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## rc10mike (Mar 27, 2008)

XSIV SPL said:


> Some tune with RTA, and some tune by ear... some use a combination of both...
> 
> I don't know specifically what you're trying to accomplish, but many folks don't use RTA when tuning...


Ill probably use a combination of both.

What Im trying to understand is tuning with a RTA. Do I use high-bit pink noise, or just do a sine sweep. The video above made sense, but it doesnt really explain anything. 

I have read over all of the Dayton iMM-6 literature, while it does a good job of explaining how to use the features, it doesn't explain WHY you would use these features and what benefits you can achieve from said features.


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## XSIV SPL (Jun 24, 2014)

rc10mike said:


> Ill probably use a combination of both.
> 
> What Im trying to understand is tuning with a RTA. Do I use high-bit pink noise, or just do a sine sweep. The video above made sense, but it doesnt really explain anything.
> 
> I have read over all of the Dayton iMM-6 literature, while it does a good job of explaining how to use the features, it doesn't explain WHY you would use these features and what benefits you can achieve from said features.


Basically, you want to minimize phase issues, then time-correct, then EQ... Or even bounce back and forth a bit at that point... there are many activities involved, but all of them lead directly back to these 3 basics.


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## SkizeR (Apr 19, 2011)

rc10mike said:


> Ill probably use a combination of both.
> 
> What Im trying to understand is tuning with a RTA. Do I use high-bit pink noise, or just do a sine sweep. The video above made sense, but it doesnt really explain anything.
> 
> I have read over all of the Dayton iMM-6 literature, while it does a good job of explaining how to use the features, it doesn't explain WHY you would use these features and what benefits you can achieve from said features.


did you watch the video i posted? do one speaker at a time, and play pink noise whil moving the mic around your ears. hopefully there are rta apps that can do averages


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## SPLEclipse (Aug 17, 2012)

rc10mike said:


> Ill probably use a combination of both.
> 
> What Im trying to understand is tuning with a RTA. Do I use high-bit pink noise, or just do a sine sweep. The video above made sense, but it doesnt really explain anything.
> 
> I have read over all of the Dayton iMM-6 literature, while it does a good job of explaining how to use the features, it doesn't explain WHY you would use these features and what benefits you can achieve from said features.


The easiest thing to do is use pink noise with an RTA like in the video above. The program he's using (Room EQ Wizard or 'REW') takes a bunch of readings and averages them together for a more accurate reading (that's why he's waving the mic around in front of his face). From there you can easily tell if there are any major peaks or dips in the frequency response and adjust accordingly. Whether or not you want to measure each individual speaker by itself or only one side at a time will depend on how your system is set up. I would at least measure one whole side (left or right) playing by itself and get each side sounding good independently rather than take a reading of all the speakers playing at once.

You can potentially use the mic for other things based in the time-domain like impulse response, but just using it for frequency response for basic EQ is what I figure you're after.


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## rc10mike (Mar 27, 2008)

Thanks guys. I felt like I was opening a can of worms on myself by asking this question. Now I see just how in depth tuning really goes and I find it pretty interesting. 

Ive already done some research on REW and Dayton USB mics for PCs but ran into a major roadblock when I found that the Audison Bit Ten D software isn't supported on Mac.

This means Ill have to invest in a cheap Windows laptop or make my Mac run Windows. FML


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## XSIV SPL (Jun 24, 2014)

SkizeR... I meant to mention to you earlier, but you cannot EQ before you phase-align, because if you're EQ'd first, changing slopes will totally mess up your EQ


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## SkizeR (Apr 19, 2011)

XSIV SPL said:


> SkizeR... I meant to mention to you earlier, but you cannot EQ before you phase-align, because if you're EQ'd first, changing slopes will totally mess up your EQ


eq one driver at a time. use 24db LR slopes for 360 degree phase change. minimal issues. like the OP said, hes not going for perfection. but you are right. this is why you do TA by distance first.

but with the way you do things (ta by ear), how do you even start. cause you cant ta by ear unless you have a matched frequency response between the pairs of drivers, and you cant eq unless you have everything in phase.. your stuck in a hole there


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## XSIV SPL (Jun 24, 2014)

SkizeR said:


> eq one driver at a time. use 24db LR slopes for 360 degree phase change. minimal issues. like the OP said, hes not going for perfection. but you are right. this is why you do TA by distance first.
> 
> but with the way you do things (ta by ear), how do you even start. cause you cant ta by ear unless you have a matched frequency response between the pairs of drivers, and you cant eq unless you have everything in phase.. your stuck in a hole there


Not really...

You're stuck in a hole if you even try to EQ first....

Changing slopes after EQ will cause cancellations all over the place...

And, btw, 24dB/ octave only works when everything is equidistant and co-planar...

I don't think I have a single 24dB/octave slope running in my system, FWIW

And yeah, the judges like it too... 

It's not so difficult to do what I do... A trained ear wouldn't hurt though...

You were saying?


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## SkizeR (Apr 19, 2011)

XSIV SPL said:


> You were saying?


you didnt answer my second part.. you claim you cant eq until everything is time aligned. and knowing that you TA by ear and you cant TA by ear accurately without having the same response on both sides, where do you start?


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## XSIV SPL (Jun 24, 2014)

You lost me there...

I'm guessing this is because your understanding of time alignment varies vastly from my own...

Yeah, I TA by ear, but I'm also currently leading the US in Extreme SQ points... using only my own tune... what do I know??


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## SkizeR (Apr 19, 2011)

XSIV SPL said:


> You lost me there...
> 
> I'm guessing this is because your understanding of time alignment varies vastly from my own...


when your tuning your car from scratch, whats the first move you make


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## XSIV SPL (Jun 24, 2014)

Everything flat-

Rough gain match...

Then rough time-align...

Then crossover points/slopes...

Time align again...

EQ...

Check TA again...

Lather, rinse, repeat...


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## percy072 (Feb 13, 2014)

If you can isolate each driver...using an RTA like REW is invaluable to help you "see" what is happening. I use a WAV file of REW's pink PN noise loaded onto a thumb drive (USB stick) set to repeat. 

I was surprised just how different each driver responds ie: left midbass vs right midbass or one playing louder than the other that (unless you have a golden ear) may not be very obvious. 

So the whole idea using full spectrum pink noise to "see" how each driver is responding. In the end...the goal is to have all the drivers matching their counterpart so that the entire system comes together in a cohesive way. 

This is a 1/1 smoothed RTA of my system so you can see that left and right's are matched close as possible rather than left tweeter to loud...or right mid peaking from 500-1000hz etc...



I know the bass is hot but it's still a work in progress. But you can see how each set of drivers response curve's are matched...that's what using an RTA does to help.


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## percy072 (Feb 13, 2014)

I'd pick up a used laptop with Win 7 already loaded. Staples usually always has good refurbs for peanuts compared with new...but it will absolutely help get the best out of your audio.


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## XSIV SPL (Jun 24, 2014)

I guess I left out one crucial point... When tuning from scratch, I do indeed start out with a tape measure and do an initial TA setting based upon distances of individual drivers to the listener's ears. However, I do NOT set the farthest driver to zero initially... I set it to 2 milliseconds delay and place delays surrounding it accordingly. This usually allows enough increase or reduction in delay to make everything line up. The acoustics of the cabin will generally dictate adjustments not foreseen if going by measurements alone. This is where you cannot measure with equipment (unless you have a microphone array and some fancy software), and have to rely upon your ears alone...

Another thing I stumbled over this weekend with a sub located very close behind the seat in a pickup cab was that playing a frequency a few hz higher than the crossover point between midbass and sub while measuring spl actually helped with a very difficult coupling of sub to front in this particular case... Followed by a manual listen, it was fairly easy to pinpoint. I think we actually did a decent job of making a sub sitting about 38 inches diagonally behind the listener sound like it was in the front stage... Not perfect, and probably never could be, but not bad considering the circumstances... The numbers we ended up at made no sense at all, but acoustics will more often than not surprise you no matter how many calculations you perform, so we deal with it.

Forgive me if my references to actual listening are confusing... Technology is great, but there is no technology (IMO, that is) which will perform as well as a decent pair of human ears just yet...


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## rc10mike (Mar 27, 2008)

I downloaded the AudioTools app to my phone today and did some testing while the kids screamed and ran around the house. I have a Droid Maxx.

The iMM-6 arrived so I downloaded the s/n specific cal file, then installed it to my phone like the instruction says.

After enabling the cal file within AudioTools there was an apparent drop off after 8khz. As if the mic was no longer picking up anything above 8khz.


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## bnae38 (Oct 3, 2015)

I had the same issue with it on the kindle. Liked the program otherwise.

I'd move on to rew..

I continue to use the imm6 with a laptop and rew. I had to make a cable with a loopback for sound card cal, but wasn't too bad.


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## rc10mike (Mar 27, 2008)

bnae38 said:


> I had the same issue with it on the kindle. Liked the program otherwise.
> 
> I'd move on to rew..
> 
> I continue to use the imm6 with a laptop and rew. I had to make a cable with a loopback for sound card cal, but wasn't too bad.


Thats unfortunate. It makes me completely doubt the readings Im getting. I even tried tones above 8k in my car that were obviously loud to my ear, but the mic wasnt picking anything up, oh well, thats $20 in the trash.


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## bnae38 (Oct 3, 2015)

The program was the issue for me, like i said i'm using the imm6 still with rew.


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## soundstreamer (Jun 2, 2015)

bnae38 said:


> I had the same issue with it on the kindle. Liked the program otherwise.
> 
> I'd move on to rew..
> 
> I continue to use the imm6 with a laptop and rew. I had to make a cable with a loopback for sound card cal, but wasn't too bad.


I've been thinking about getting the same mic and using REW. Could you tell me exactly what cables are needed to run into the sound card?


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## unix_usr (Dec 4, 2013)

rc10mike said:


> Thanks guys. I felt like I was opening a can of worms on myself by asking this question. Now I see just how in depth tuning really goes and I find it pretty interesting.
> 
> Ive already done some research on REW and Dayton USB mics for PCs but ran into a major roadblock when I found that the Audison Bit Ten D software isn't supported on Mac.
> 
> This means Ill have to invest in a cheap Windows laptop or make my Mac run Windows. FML


I'm a mac user too - I use a Macbook Pro laptop, running VMWare Fusion - my DSP (built into my amplifier) doesn't run well with Windoze 7 so I maintain a Windows XP VM just for tuning purposes. REW runs native on the Mac at least, I just have to change the settings/tweak things via the VM


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## gregerst22 (Dec 18, 2012)

XSIV SPL said:


> Forgive me if my references to actual listening are confusing... Technology is great, but there is no technology (IMO, that is) which will perform as well as a decent pair of human ears just yet...


What I think we need is somebody that can tell us how to properly use our ears to tune. I'm not much more than a novice when it comes to this and my technique has been to do all the phase, level, t/a stuff and establish baseline tune with the RTA. Then while listening to my familiar music I note anything that sounds bad or off, like some portion of a song, then I go listen to it on my reference system a few times. After that I go straight to the car and fiddle with the eq's until I locate the frequencies in question then I try to get it to sound as close to my reference system as possible. I may go back and forth a few times. That's just for one trouble spot. Eventually by doing this over and over, it can take weeks or more, I will eliminate all the issues I can detect and the system will sound pretty good.


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## bnae38 (Oct 3, 2015)

soundstreamer said:


> I've been thinking about getting the same mic and using REW. Could you tell me exactly what cables are needed to run into the sound card?


I use 3 cables, two of which are always connected. Trrs (4pin like the mic) extender. Trrs splitter. And a regular 3pin 3.5mm to 3pin micro cable to connect to the aux in on my prs.

Splitter: http://www.amazon.com/Willow-Wind-Female-Headphone-Splitter/dp/B015GMYBEC?ie=UTF8&psc=1&redirect=true&ref_=oh_aui_detailpage_o03_s00

Pretty basic. I heat shrunk the hell out of it to bulk it up and reinforce it. I'll plug both ends into laptop for loopback when i cal the sound card.


Extender: http://www.amazon.com/FosPower-Auxi...&redirect=true&ref_=oh_aui_detailpage_o05_s00

Heat shrunk the ends of this one good too including the shield on the male end where i could possibly touch it. Shield is mic input on trrs. I cut the cable off and added a switch from audio L to mic input that i can toggle when i want to cal. 



The connector i use for aux input I can't seem to find an example of at the moment. I made one with a regular 3.5mm cable and a micro 3pin. Not sure how you'll connect laptop to your deck anyway, may be full size 3.5mm.



I can throw some pics up later, gotta hit the road. Fwiw.. i might just get a usb mic if i had to do it all over again .


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