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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Dan56
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Re: Methods of RTA'ing

#16 Post by Dan56 »

byacey wrote: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.
Yes, so I used this site: http://www.audiocheck.net/audiofrequenc ... netone.php where I could set the db of the down loaded tone. Again, not perfect, but assuming the mic, computer and software perform the same all the time, as long as I'm always using this particular tool it's ok. Certainly I can not confidently use it as a reference for comparison to other results made from a different analyzer tool.

It's like using a micrometer that is not zeroed. As long as I'm only using it to find the difference between two measurements it's ok. However, if I need to make sure that part is exactly .250 then I had better zero it to a test block. This is assuming the treads on the spindle are not worn. If they are, then nothing will ever be accurate. It's the carpenter always using the same rule or tape. Your measurement may be different. :)

Granted I'm very new this this level of understanding of sound and running a PA, but if all I need to know is differences, the Audio Tool calibrated as I suggest will give me that. If I need to hit the mark on a frequency, well then I won't be using my ears or this tool. :)

byacey
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Re: Methods of RTA'ing

#17 Post by byacey »

I might be OK for some A/B comparisons, but not much more than that.
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Chris_Allen
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Re: Methods of RTA'ing

#18 Post by Chris_Allen »

byacey wrote:I might be OK for some A/B comparisons, but not much more than that.
I agree.

The point of calibration is to align with a known reference.

If you take three components, two of which are unknown (in this case, the mic and the speakers), you are only aligning to each other.
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Re: Methods of RTA'ing

#19 Post by SeisTres »

I'm really surprised no one has mentioned Room Eq Wizard from hometheatershack. It is really one of the most powerful era tools available and it's free! I'm not going to lie and say it is simple to learn; the learning curve can be steep but it is definitely worth learning. The rta Mic can had under $50 if you look around and you can use interfaces or simply run it through a mixer and into the line in on your pc.
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Rich4349
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Re: Methods of RTA'ing

#20 Post by Rich4349 »

On a different, yet related note: if one were to do the outdoor baseline RTA procedure, barring midair suspension, is burying a DR250 face up to its surface the (or a) proper way to go? Provided nothing else is around to reflect sound within _______ feet?
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Re: Methods of RTA'ing

#21 Post by Bruce Weldy »

Rich4349 wrote:On a different, yet related note: if one were to do the outdoor baseline RTA procedure, barring midair suspension, is burying a DR250 face up to its surface the (or a) proper way to go? Provided nothing else is around to reflect sound within _______ feet?

Are you trying to produce a chart or a good-sounding EQ curve?

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Re: Methods of RTA'ing

#22 Post by Rich4349 »

Good sounding eq setting.
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Re: Methods of RTA'ing

#23 Post by Bruce Weldy »

Rich4349 wrote:Good sounding eq setting.

Then you should EQ it in the position it will be in when you are listening to it.

If you plan to put 'em in the ground to listen to 'em .... then go for it.

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Re: Methods of RTA'ing

#24 Post by Rich4349 »

And all other (reasonably controllable) variables aside, HOW much of a difference could the amplifier make in the final EQ settings? (Per each frequency, not dB per se)
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Re: Methods of RTA'ing

#25 Post by Bruce Weldy »

Rich4349 wrote:And all other (reasonably controllable) variables aside, HOW much of a difference could the amplifier make in the final EQ settings? (Per each frequency, not dB per se)
If it's a decent amp, it should make no difference in your EQ settings. The amp's job is to recreate the signal it's given at a higher level .... usually pretty flat from 20hz to 20khz.....at least that's the range they give when showing their specs for power.

Is that what you are asking?

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Re: Methods of RTA'ing

#26 Post by Rich4349 »

Yes. I've dipped my toes very slightly into the audiophile (not phool) pool and those in the analog / tube camp might have tainted my thinking. But the difference between two "common" SS amps is probably an order of magnitude less than a common SS and a mid level tube. Not that I'm venturing into tube-land, just using that as a greater difference for illustration purposes.

As for the RTAing:I thought in room response was done AFTER the "no outside influences" baseline was established? "Fine tune from there" and such rubbish.
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Re: Methods of RTA'ing

#27 Post by Bruce Weldy »

Rich4349 wrote:Yes. I've dipped my toes very slightly into the audiophile (not phool) pool and those in the analog / tube camp might have tainted my thinking. But the difference between two "common" SS amps is probably an order of magnitude less than a common SS and a mid level tube. Not that I'm venturing into tube-land, just using that as a greater difference for illustration purposes.

As for the RTAing:I thought in room response was done AFTER the "no outside influences" baseline was established? "Fine tune from there" and such rubbish.
If you are planning to tour with your setup, then yes, having a flat outdoor setup (with cabinets above ground) gives you a starting point.

In your house - just RTA it, EQ it, make it sound good and get on with enjoying it.

Two different animals here.

And remember, like 99% of the people involved in live sound.....99% of the people who opine about home theater are only regurgitating what they've heard from some sales guy.

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Bill Fitzmaurice
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Re: Methods of RTA'ing

#28 Post by Bill Fitzmaurice »

Rich4349 wrote: As for the RTAing:I thought in room response was done AFTER the "no outside influences" baseline was established? "Fine tune from there" and such rubbish.
The main value of a true 1/2 space anechoic measurement is to find out if the speaker is working as it should. More often than not a user need do that only if something doesn't sound right.

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Re: Methods of RTA'ing

#29 Post by byacey »

Years ago the Ultralinear or Williamson tube output configuration was highly regarded because it minimized distortion and approached something that a good solid state amp could easily accomplish.

Then when clean, low noise solid state amps were the norm, the audio-files decided they wanted distortion. There's just no pleasing these sorts.
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Re: Methods of RTA'ing

#30 Post by Rich4349 »

Bill Fitzmaurice wrote:The main value of a true 1/2 space anechoic measurement is to find out if the speaker is working as it should. More often than not a user need do that only if something doesn't sound right.
Idk if this qualifies, but I've had some (polite) criticism of the bottom end lacking, around 100hz. I would like to see what it's really doing down there, no distortions, exaggerations, minimizing, no nothing. How much EQing can I do safely at that end, and does that "rearranging" of the curve come at a cost to the mids? Robbing Peter to pay Paul? (NOT that the mids don't have plenty to borrow from!)
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