Methods of RTA'ing

EQ guys are using on their cabs/systems. A good starting place if you don't have your own RTA.
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Chris_Allen
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Methods of RTA'ing

#1 Post by Chris_Allen »

I'm looking for a cost effective way of doing RTA's. I have a DEQ2496 which is great but I'd like a way of doing it without having to insert that into the signal chain.

Is a signal generator and SPL Meter the way forward, or is using pink noise the only way to get good results?

Ideally, I don't want to lug round a laptop either. When it comes to balancing a system, my ears alone are more than a little crap.
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Bill Fitzmaurice
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Re: Methods of RTA'ing

#2 Post by Bill Fitzmaurice »

Something like this is the only other viable option:
http://www.phonic.com/en/paa3.html

But you still need EQ to make the corrections, so the DEQ2496 is the better method.

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Chris_Allen
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Re: Methods of RTA'ing

#3 Post by Chris_Allen »

I'm not sure I do enough RTA'ing of other systems to warrant the £300 prices tag, cool looking tool though.
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Bill Fitzmaurice
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Re: Methods of RTA'ing

#4 Post by Bill Fitzmaurice »

Chris_Allen wrote:I'm not sure I do enough RTA'ing of other systems to warrant the £300 prices tag, cool looking tool though.
If it's measuring other systems you want to do then it's either one of those or lugging a laptop or pad and USB mic. You can't see a graphic readout on a meter.

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Chris_Allen
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Re: Methods of RTA'ing

#5 Post by Chris_Allen »

Well, after a moment of being a numpty, I remembered I had a Zoom H4. PLugging that into the Mac brings it up as a H4 input capable of 48KHz sampling.

I looked at the cost of SMAART and that is way out of my price range! I did find an app called Spectre for $50, has anyone any experience of using that?
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Bruce Weldy
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Re: Methods of RTA'ing

#6 Post by Bruce Weldy »

Chris_Allen wrote: numpty
I done been to three county fairs and a goat roping contest....and I ain't never heard no word like dat.....

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Chris_Allen
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Re: Methods of RTA'ing

#7 Post by Chris_Allen »

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Bruce Weldy
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Re: Methods of RTA'ing

#8 Post by Bruce Weldy »

Chris_Allen wrote:Just for your consumption:

http://www.oxforddictionaries.com/defin ... ish/numpty

Since I didn't know that, I guess I'm a numpty too.

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"A system with a few knobs set up by someone who knows what they are doing is always better than one with a lot of knobs set up by someone who doesn't."

Grant Bunter
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Re: Methods of RTA'ing

#9 Post by Grant Bunter »

It's OK Bruce, the word only came into being after you went to school!

I didn't know of it either.

Chris, worrying that you know it, but also found a definition...
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dswpro
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Re: Methods of RTA'ing

#10 Post by dswpro »

Parts Express carries a calibrated mic which will plug into your phone for around fifteen dollars (US) I use the AudioTool program for my Android phone -- works pretty well.
I've also used my DEQ with a flat response microphone and a pink noise source. (AudioTool also has a generator) Before I had my DEQ or android app I also used Goldwave to generate a sweep tone and record the sweep tone, then use the spectrum analyzer function on Goldwave to see the system response.

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Chris_Allen
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Re: Methods of RTA'ing

#11 Post by Chris_Allen »

I've seen the Dayton calibrated mic before but as usual, I can't find anything equivalent in the UK. That would most likely be the ideal solution.
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Dan56
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Re: Methods of RTA'ing

#12 Post by Dan56 »

I use this program: https://play.google.com/store/apps/deta ... Tool&hl=en Which I might be the same program dswpro mentioned.

I downloaded test tones at the frequencies a 31 band EQ and played them into the mic on my Android to calibrate it's mic. The program allows you to adjust each band until the scale reads as the test tone. Works great and cheap.

Dan

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Chris_Allen
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Re: Methods of RTA'ing

#13 Post by Chris_Allen »

The only problem with doing a self calibration is that you need a flat output source as a reference point, which I don't believe i have.
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6xDR200, 2xT39, 2xT48, 2xJack110, 1xOmni10.5, 1xAutotuba, 1xT18, 1xSLA Pro, 1xW8, 1xW10

Dan56
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Re: Methods of RTA'ing

#14 Post by Dan56 »

Chris_Allen wrote:The only problem with doing a self calibration is that you need a flat output source as a reference point, which I don't believe i have.

No, you are calibrating the mic of your Android or Ipad. Using individual tones, one at a time played into the Android/Ipad via their built in mic allows you to see what the mic's offset needs to be. You then adjust that frequency in the program. Do that for every tone of the 31 bands.
You now have the program properly reading tones based on the idiosyncrasies of the mic. The program will read in 1/6th tones also. I haven't check, but you might be able to calibrate at that level.

Granted, the unit is not what you would be doing research with, but it will serve the purpose for our needs.

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Re: Methods of RTA'ing

#15 Post by byacey »

The way I read the description is that you can change the mic to match that of a known calibrated mic. If the supposed calibrated mic has errors, so will your emulated calibration.

I'm not sure that I would trust a $0.35 iphone mic cartridge for any accuracy, under any circumstances.

Short of that, I can't see any possible way to properly calibrate any microphone without a calibrated sound source.
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