# RTA/REW- 90 degree or 0 file when measuring?



## JMichaels (Nov 17, 2006)

Been putting in some hours tuning. Prefer to use a 90 degree file on my mic and hold it upright around my head going from ear to ear while I sit in the drivers seat. Then take the average. I was wondering what are some thoughts on this much covered subject and mic placement/file. 

What can be suggested when doing the right and left separately? When doing just the right side for example do you think you should still do equal measurements around the head or just concentrate on the right ear?

I've also tried using sweeps and tones while I sit in the seat and watching the peak meter on the RTA. Isolating tones and seeing just how much variance there is from say and inch over to the right or to the left. Once you get above 315 - 400 its amazing to me you can figure anything out at all. So many reflections and issues.


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## SPLEclipse (Aug 17, 2012)

I use the off-axis calibration for my mic that was calibrated by Cross Spectrum. It makes more sense, as reflections act as a sort of secondary point source anyway, and there's reflections everywhere (as you have noticed, lol). Honestly though, the on-axis calibration works just as well, as there is very little deviation between the two, and only well up into the higher frequencies where absolute precision isn't required.

There's differing opinions on where to measure, with most people (I think) doing 4-8 measurements all over the head position, left, center and right for both channels. I prefer to point my mic primarily at the source of the sound because I've gotten far more consistent results, and better tunes that way. If I'm measuring, for example, the right channel, they would be like this: pointed directly R, 90 degrees away from the length of the car (2 measurements, one at top of ear level and one below), next I'll move to about 45 degrees away, and do another set of "top" and "bottom of the ear measurements. Then I point the mic almost, but not quite, straight ahead and take two more.

One thing I should point out: if you are measuring with your head in place, the head related transfer function (HRTF) will interfere with higher frequencies. That's not necessarily a bad thing per se, but it has to be accounted for and shouldn't be lumped in with non HRTF measurements for averages.


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## JMichaels (Nov 17, 2006)

So are you saying you are using the 90 degree off axis file and holding the mic next to your ear with the tip of the mic pointed up toward the roof. And taking a set of measurements? And then rotating your head for another two sets. Or are you using the 90 and pointing it directly at the speaker and then the other two? I find it easier to get the mic next to my ear when its straight up and down. I have seen this suggested by several people including helix.


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## emilime75 (Jan 27, 2011)

SPLEclipse said:


> Honestly though, the on-axis calibration works just as well, as there is very little deviation between the two, and only well up into the higher frequencies where absolute precision isn't required.


What mics are everyone using? I just recently started taking actual measurements of my car using REW and a MiniDSP UMIK. I was curious to see if I would get different measurements by holding the mic at different angles but keeping the end in the same location. The variance was so tiny it's completely negligible. I would assume any good omni mic would have the same results.

So, like I said, I am new to measuring but it would seem to me that taking a measurement at the left ear, then the right and averaging their responses and adjusting as best you can would be the way to go. Maybe my thinking is off, but I would also think having both left and right channels playing while measuring both sides of your head would be ideal as well, considering all the reflections, both ears will be hearing both channels at the same time. So if you're measuring your left ear position, for example, you will definitely be hearing things there that are coming from the right channel, delayed of course, because of the reflections, but it will still be there.


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## SPLEclipse (Aug 17, 2012)

JMichaels said:


> So are you saying you are using the 90 degree off axis file and holding the mic next to your ear with the tip of the mic pointed up toward the roof. And taking a set of measurements? And then rotating your head for another two sets. Or are you using the 90 and pointing it directly at the speaker and then the other two? I find it easier to get the mic next to my ear when its straight up and down. I have seen this suggested by several people including helix.


I don't tune with my head in place because it's not necessary and only gets in the way. I tune form outside the car or the passenger seat. My speakers are all in the dash so my body doesn't get in the way (probably helps that I'm 130lbs soaking wet, lol). You can point the mic up, down or straight ahead. Try them all. There will probably be a slight roll-off above 10khz with a straight up or down position, but not enough to change anything drastically.



emilime75 said:


> What mics are everyone using? I just recently started taking actual measurements of my car using REW and a MiniDSP UMIK. I was curious to see if I would get different measurements by holding the mic at different angles but keeping the end in the same location. *The variance was so tiny it's completely negligible. I would assume any good omni mic would have the same results.*
> 
> So, like I said, I am new to measuring but it would seem to me that taking a measurement at the left ear, then the right and averaging their responses and adjusting as best you can would be the way to go. Maybe my thinking is off, but I would also think having both left and right channels playing while measuring both sides of your head would be ideal as well, considering all the reflections, both ears will be hearing both channels at the same time. So if you're measuring your left ear position, for example, you will definitely be hearing things there that are coming from the right channel, delayed of course, because of the reflections, but it will still be there.


I agree with the bolded statement. As for mics, I've owned a ton of them. I measure with this mic, calibrated by Cross Spectrum Labs:

iSEMcon GmbH

I also have several DIY mics that I measure with, including one "shorty" mic/preamp unit I built specifically because it's hard to position a long mic wand in a car with a wall right behind the seat, lol. I had contemplated doing a small run of these mics but I just don't have the time right now.

As for your other question, tune whatever way makes sense to you, but if that's the way you do it you won't get results that are consistent with what everyone else is doing. Typically you tune one side at a time, with the other side completely off. By doing this, you get independent frequency and phase information, which you can then match to the other side. Ideally you want both sides to look exactly the same in both the time and frequency domains to establish the best soundstage (with perhaps some variance in the high frequency amplitude levels to prevent side bias). One you tune both sides, you can measure the combined result to see if the phasic interaction between the two is creating nulls or peaks in the FR. In a perfect world, the L and R measurements would overlay on top of each other perfectly, and the combined measurement would look exactly the same but slightly higher in amplitude.

Naturally you will hear L information from your R ear and vice-versa, this is known as crosstalk and will happen in every audio system except headphones. This is probably why some people use the "all over the head area" mic positioning technique. This gets into the discussion of dispersion (see: Patrick Bateman) and sound power (see: ErinH), and other areas too complicated to go over in this thread. I find it best to generally ignore the idea of crosstalk when tuning. Know that it's there, know that it's affecting your results, accept it, and go with it.


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## 156546 (Feb 10, 2017)

There are essentially three kinds of measurement mics. Pressure mics, free field mics and random incidence. Free field mics are the ones (or the measurement condition) for which you'd use the 90 degree orientation. Pressure and random incidence are essentially interchangeable. The inside of a car is not a free field, it's random incidence at high frequency and pressure at low frequency. In this case and with an omnidirectional mic, the regular pointing forward orientation is correct. Most of the microphones available at reasonable prices are pressure mics and the 90 degree calibration file is there in case you need to make a free field measurement. Such a measurement might be a ground plane measurement of a speaker in a box or in an infinite baffle outside.

So, the answer for this question is that it doesn't matter. 

Measuring Sound with Microphones


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## HCWLSU101 (Apr 30, 2009)

So how different will measuring with the UMIK-1 pointed upward using the 90 degree file differ from straight forward using 0 degree calibration for the high end. I feel my tweeters are much brighter than shown pointing the mic upward. Probably due to reflections but I’m not sure how to see that info?


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## 156546 (Feb 10, 2017)

The difference between the two calibration files. Very small difference and only at VERY high frequencies.


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## Ge0 (Jul 23, 2007)

GotFrogs said:


> The difference between the two calibration files. Very small difference and only at VERY high frequencies.


Thank you for that clarification.

Ge0


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## AudioGal (Oct 16, 2019)

Below is a quick graph of my UMK-1 USB mic for giggles and grins. The spec sheet says with a calibration file it is +/-1 dB but who knows for sure. Either way here is some data. Other mic's may measure better or not. between 0 and 90.

0 = on axis file
90 = 90 degree file
Diff = a difference between the two cal files. 

Just some data for the discussion


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## Mauian (Jul 25, 2019)

AudioGal said:


> Below is a quick graph of my UMK-1 USB mic for giggles and grins. The spec sheet says with a calibration file it is +/-1 dB but who knows for sure. Either way here is some data. Other mic's may measure better or not. between 0 and 90.
> 
> 0 = on axis file
> 90 = 90 degree file
> ...


Are both of these measurements with the microphone pointed up, just switching the calibration file?


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## AudioGal (Oct 16, 2019)

The files are the calibration files (offset values) for the microphone for doing measurements to a level of accuracy of +/- 1 dB supplied by Mini DSP.


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## Mauian (Jul 25, 2019)

Ah, nevermind. These are just calibration files graphed. Sorry!


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## Mauian (Jul 25, 2019)

So does this mean that the mic at 90 degrees is MORE sensitive to the higher frequencies (hence the correction to decrease it more)? That seems counter to a lot of people’s experience where people feel that their top end is a bit bright when measured with mic pointing up and then get a reading with greater loudness with the microphone pointed at the tweeters...


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## Mauian (Jul 25, 2019)

Just replying to myself here, but if the mic will actually not measure THAT different between the two calibration files (as Andy stated) then maybe this difference in calibration files from miniDSP is what accounts for what people (and I have also) experienced (with higher frequencies measuring lower than they actually sound)?

Or, in other words, the calibration files seem significantly different, but if they actually shouldn’t make much of a difference with this type of microphone in a car, then maybe this is what causes the phenomenon that people experience at the higher frequencies?


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## Mauian (Jul 25, 2019)

Like, is miniDSP assuming people are using the 90 degree file in a free field application (NOT a car). I would think so, right?

Regardless, it would seem that the choice of calibration file makes a significant difference and we should all be using the zero degree file in our cars? (A 2dB difference starting around 7k is certainly something we could notice...)


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## AudioGal (Oct 16, 2019)

The calibration files show that there is a difference between 0 and 90 degree (pointing straight up) and it is not insignificant for the Mini DSP UMK-1 mic To use the 0 file while holding the mic straight up you would most likely get a substantial error above 2Khz according to the calibration file. All things being equal or according to the manufacture supplied data. If you use the wrong file with this mic the tune will become very bright in the top end as the wrong mic correction is used and extra frequency energy will be added by the person tuning to compensate because the calibration offset is not being applied to the microphone measurement before it is displayed on the RTA. Hopefully that makes sense.


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## Ge0 (Jul 23, 2007)

AudioGal said:


> Below is a quick graph of my UMK-1 USB mic for giggles and grins. The spec sheet says with a calibration file it is +/-1 dB but who knows for sure. Either way here is some data. Other mic's may measure better or not. between 0 and 90.
> 
> 0 = on axis file
> 90 = 90 degree file
> ...


"Giggles and grins". You're so polite. Round these parts we say "for sh!tz n giggles" 

Thanks for sharing your cal file. Quite a bit different than what I was expecting considering the earlier conversation.

Just for clarification. I take 0 degree as the mic being horizontal and possibly pointing towards the sound source. I take 90 degree as the mic held vertical pointing up towards the ceiling. Is this a correct assumption?

Ge0


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## Mauian (Jul 25, 2019)

AudioGal said:


> The calibration files show that there is a difference between 0 and 90 degree (pointing straight up) and it is not insignificant for the Mini DSP UMK-1 mic To use the 0 file while holding the mic straight up you would most likely get a substantial error above 2Khz according to the calibration file. All things being equal or according to the manufacture supplied data. If you use the wrong file with this mic the tune will become very bright in the top end as the wrong mic correction is used and extra frequency energy will be added by the person tuning to compensate because the calibration offset is not being applied to the microphone measurement before it is displayed on the RTA. Hopefully that makes sense.


It does. Thanks! Just trying to combine this knowledge with what Andy is saying:

1) Andy is saying that a car is NOT a free field environment, which is the only place where a 90 degree calibration file should be used

2) Many of us, myself included, have been measuring with the mic pointed up and with a 90 degree file

3) this is incorrect  and has been leading to potentially bright top ends.

Now should we all be pointing the mic at the speakers when measuring? I would think yes...

We should all be using zero degree files, right?

I admit different mics might be different, but it still doesn’t change the fact they the car is not free field...


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## Mauian (Jul 25, 2019)

Ge0 said:


> "Giggles and grins". You're so polite. Round these parts we say "for sh!tz n giggles"
> 
> Thanks for sharing your cal file. Quite a bit different than what I was expecting considering the earlier conversation.
> 
> ...


Yep. I agree with that assumption.


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## AudioGal (Oct 16, 2019)

Ge0 said:


> "Giggles and grins". You're so polite. Round these parts we say "for sh!tz n giggles"
> 
> Thanks for sharing your cal file. Quite a bit different than what I was expecting considering the earlier conversation.
> 
> ...


LOl, I am trying to be on my best behavior  

and yes.

0 = horizontal pointing at the sound source (speaker) .
90 = orthogonal to the sound source or put another way pointing at the ceiling.


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## Mauian (Jul 25, 2019)

AudioGal said:


> The calibration files show that there is a difference between 0 and 90 degree (pointing straight up) and it is not insignificant for the Mini DSP UMK-1 mic To use the 0 file while holding the mic straight up you would most likely get a substantial error above 2Khz according to the calibration file. All things being equal or according to the manufacture supplied data. If you use the wrong file with this mic the tune will become very bright in the top end as the wrong mic correction is used and extra frequency energy will be added by the person tuning to compensate because the calibration offset is not being applied to the microphone measurement before it is displayed on the RTA. Hopefully that makes sense.


I guess to try to be more clear, we really should never use the 90 degree file inside the car, even if pointed up, as the car is not a free field measurement environment. Correct?

Sure some mic calibration files might not have this drastic a difference, but even if they didn’t, it’s still an incorrect application, no?


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## Ge0 (Jul 23, 2007)

Mauian said:


> I guess to try to be more clear, we really should never use the 90 degree file inside the car, even if pointed up, as the car is not a free field measurement environment. Correct?
> 
> Sure some mic calibration files might not have this drastic a difference, but even if they didn’t, it’s still an incorrect application, no?
> 
> ...


I'm thinking this would be a good question for miniDSP. Too much speculation going on around here...

Ge0


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## Mauian (Jul 25, 2019)

Ge0 said:


> I'm thinking this would be a good question for miniDSP. Too much speculation going on around here...
> 
> Ge0


Agreed, but given Andy’s statement of:

“The inside of a car is not a free field, it's random incidence at high frequency and pressure at low frequency. In this case and with an omnidirectional mic, the regular pointing forward orientation is correct.”

This would seem to mean that the zero degree file is the one to use.

I just don’t see another conclusion to be made given that the zero degree file is intended to be used when the mic is pointed forward at the audio source...

I think/assume Andy said it didn’t matter which file was used assuming that the differences were small, but as we can see here, for some microphones the difference can be significant. But I’ll let Andy correct me if the above does not capture his thoughts accurately 


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## AudioGal (Oct 16, 2019)

Mauian said:


> It does. Thanks! Just trying to combine this knowledge with what Andy is saying:
> 
> 1) Andy is saying that a car is NOT a free field environment, which is the only place where a 90 degree calibration file should be used
> 
> ...


 Each to their own for how they want to measure.

I put data forward from the manufacture that suggests it would be good to use the proper Cal file based on the orientation of the microphone. Some mic's may be of much higher quality and the multi-orientation cal files will match while other mics may not but you should check before assuming. that s all.

I explained a potential reason for what you think others may be hearing as brightness previously and it has nothing to do with how you point the mic and maybe from using the wrong cal file for that orientation. With my mic I make sure to use the correct cal file. There could be many other reasons for this outcome that you talk about so looking at it from a single variable analysis usually takes a person down the wrong path.

As to how you or others choose to measure, I did not go there


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## Mauian (Jul 25, 2019)

AudioGal said:


> Each to their own for how they want to measure.
> 
> I put data forward from the manufacture that suggests it would be good to use the proper Cal file based on the orientation of the microphone. Some mic's may be of much higher quality and the multi-orientation cal files will match while other mics may not but you should check before assuming. that s all.
> 
> ...


Okey doke. Just was discussing the data and how it may apply to one of the questions in this thread. Sorry if it came off like I was implying anything about what you said.


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## Mauian (Jul 25, 2019)

As an aside, or maybe related point?, I may disagree with your statement that it has nothing to do with the microphone orientation. I think it MAY have something to do with microphone orientation if that is causing you to use a 90 degree file.

Andy is saying that 90 degree calibration files are for free field measurement environments, which the car isn’t. Just because the mic is held upward or orthogonal doesn’t make the car a free field environment. In this case the 90 degree file still is not the correct choice. 

Again, just trying to make sense of what Andy is saying and the use of these files in a car.

Totally agree that the use of the incorrect file can lead to unintended results...


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## Mauian (Jul 25, 2019)

Ge0 said:


> I'm thinking this would be a good question for miniDSP. Too much speculation going on around here...
> 
> Ge0


On the miniDSP website it says the zero degree calibration file should be used for 2 channel systems or for single speaker measurements with the microphone pointed at the speakers. The 90 degree file should be used when measuring a surround system (5.1 or 7.1) with multiple speakers spread out around the room with the microphone pointed at the ceiling. They don’t talk specifically about a car though.

Just want to stress that of course people can measure any way they like. I’m just trying to understand the best way to achieve accurate measurements. 

It’s a fundamental topic that deserves some discussion. I mean, I’ve seen a ton of videos with people measuring with the mic pointed up in a car. It was a bit shocking to hear from Andy that he didn’t understand where that came from. But reading the above, I’m starting to understand now (I think!).

Also of note, the microphone that Audiofrog sells comes with a mount that allows you to mount the microphone to the headrest. It has the microphone pointing straight forward when mounted (not pointed at the ceiling). I doubt this was unintentional given Andy’s posts above.


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## Mauian (Jul 25, 2019)

Some old photos from posts I could find of the measurement rigs of Skizer and another member (John Kiser?).

I believe these setups have the mics pointed forward.

Of course these photos do NOT mean that pointing the mic at the speakers is the only or best way to measure. I’m just trying to collect some expert opinions.

Are they aimed this way for a particular purpose / reason? I believe Nick’s mics are the ECM Behringer (an omnidirectional condenser mic) - so in a car, an environment that is NOT free field, the mic should be pointed at the speakers (and a zero degree calibration file should be used, no?)

At any rate just interesting. Again, people can measure anyway they like.



















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## 156546 (Feb 10, 2017)

The "difference" between the two curves above at 20k is not 0dB, its about 12dB. It appears you've ADDED the two curves rather than subtracting one from the other. For example, 6+(-6) = 0 but 6-(-6) = 12.


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## 156546 (Feb 10, 2017)

How many of you are Bluetoofing the stimulus signal to the head unit when you're tuning cars? How many of you have a pink noise track ripped to your iTunes or some other app that you use when you're tuning cars?


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## Mauian (Jul 25, 2019)

GotFrogs said:


> How many of you are Bluetoofing the stimulus signal to the head unit when you're tuning cars? How many of you have a pink noise track ripped to your iTunes or some other app that you use when you're tuning cars?


I use a pink noise track that I play through the Apple Music app. My phone is plugged in via USB to the car’s factory head unit. I play most of my music in this configuration.


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## Mauian (Jul 25, 2019)

GotFrogs said:


> The "difference" between the two curves above at 20k is not 0dB, its about 12dB. It appears you've ADDED the two curves rather than subtracting one from the other. For example, 6+(-6) = 0 but 6-(-6) = 12.


It looks like at 20k it should be 0 - (-6) = 6, but maybe I’m missing something?


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## 156546 (Feb 10, 2017)

Mauian said:


> Yep. I agree with that assumption.
> 
> 
> Sent from my iPhone using Tapatalk


Oops. I read the legend incorrectly. Yes. You're right.


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## Ge0 (Jul 23, 2007)

Mauian said:


> Some old photos from posts I could find of the measurement rigs of Skizer and another member (John Kiser?).
> 
> I believe these setups have the mics pointed forward.
> 
> ...


I spoke with Nick about his mic array because I was interested in trying something similar. He mentions it not working the way he wanted and that he does not use it anymore. Rather, he sits in the car and waves the mic from ear to ear while taking long pink noise averages using REW. He mentions getting better results that way.

Interesting enough, I get the best results I've achieved so far by using this rig:












__ https://www.facebook.com/video.php?v=3313537712096672



It waves the mic back and forth automatically while I take measurements. I use the sine sweep measurement function in REW. Take 5 to 10 measurements. Then average them together. I also use the mics 90 degree cal file.

Two important take aways here. The first is that this method is repeatable. Results do not vary wildly from one session to another. The second is it produces a natural sounding frequency response to me using a "Harman like" house curve. I may make slight tweaks from song to song using the tone controls on my head unit. But, that is more recording dependent that system playback dependent.

Ge0


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## Ge0 (Jul 23, 2007)

GotFrogs said:


> How many of you are Bluetoofing the stimulus signal to the head unit when you're tuning cars? How many of you have a pink noise track ripped to your iTunes or some other app that you use when you're tuning cars?


I use my laptops built in speakers 

Ge0


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## robabeatle (Jun 24, 2020)

Maybe this is why I have a bright top end and sibilance issues. I was using the 90 degree file with mic pointed up. Strange how this seems to be touted by a lot of people as the correct method.


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## Mauian (Jul 25, 2019)

Ge0 said:


> I spoke with Nick about his mic array because I was interested in trying something similar. He mentions it not working the way he wanted and that he does not use it anymore. Rather, he sits in the car and waves the mic from ear to ear while taking long pink noise averages using REW. He mentions getting better results that way.
> 
> Interesting enough, I get the best results I've achieved so far by using this rig:
> View attachment 280067
> ...


This is cool. I saw when Erin made it and wanted to do something similar but wanted something that was battery powered or powered by usb as I park my car a bit of a distance from my house...then I gave up...hahaha 


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## Mauian (Jul 25, 2019)

Ge0 said:


> I use my laptops built in speakers
> 
> Ge0


Nice! So you tune your laptop speakers? That must sound wicked 


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## Mauian (Jul 25, 2019)

Just to throw it out there, I tune with pointing the mic straight up and waving it around my ears with infinite averaging in REW. I think the results are pretty great but I’m always interested in improving...especially if there is good reason to do it another way.


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## 156546 (Feb 10, 2017)

If you're averaging while sitting in the car and waving the microphone around each side of your head, you'll probably require an adjustment to the target. You're going to measure less high frequency with the mic on the far side of your head and more when it's on the near side of your head. 

I have a little array I've used for years that works really well with my target curve (which is the "harman" target curve because I used to work at "Harman". unless they've published something since I left).


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## Ge0 (Jul 23, 2007)

Mauian said:


> Nice! So you tune your laptop speakers? That must sound wicked
> 
> 
> Sent from my iPhone using Tapatalk


I was being a smart a$$...

Ge0


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## Ge0 (Jul 23, 2007)

Mauian said:


> This is cool. I saw when Erin made it and wanted to do something similar but wanted something that was battery powered or powered by usb as I park my car a bit of a distance from my house...then I gave up...hahaha
> 
> 
> Sent from my iPhone using Tapatalk


Detached garage helps. Except when the weather starts to get cold...

Ge0


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## 156546 (Feb 10, 2017)

Just remember if you decide to set up some kind of an array, that the average of the micropohne measurements is not the sum of the measurements. You can't just get a 6 input USB interface and combine the output of the mics. You need software or hardware that provides an average. The spatial average is the average of the MAGNITUDE responses WITHOUT the phase response.


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## Ge0 (Jul 23, 2007)

GotFrogs said:


> If you're averaging while sitting in the car and waving the microphone around each side of your head, you'll probably require an adjustment to the target. You're going to measure less high frequency with the mic on the far side of your head and more when it's on the near side of your head.
> 
> I have a little array I've used for years that works really well with my target curve (which is the "harman" target curve because I used to work at "Harman". unless they've published something since I left).


I'd like to see some details on your array. I want to build something like Earl Geddes suggested in his white paper. But, don't have a software that can process multiple microphone inputs and average them. REW is powerful and free. But, does not support multiple mic inputs.

It's been a few years since I've visited Harman. To my knowledge nothing has changed with their system applications. Do you know a guy named Brad Hamm? He now leads the group and is a member of my local audio club. I can ask him at our next meeting.

Ge0


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## jtrosky (Jul 19, 2019)

Just as another data point, Helix also recommends the "mic pointing straight up and moving from ear to ear" method of measuring in their Sound Tuning magazines.

I also take measurements with the MIC pointing up, moving ear to ear and using the 90-degree calibration file - and I use a 20-minutes-long "Lab Grade Pink Noise" track that is in .wav format and played directly from my headunit (stored on a 256gb USB thumb drive that is always installed). 

Ultimately, most people are only going to use the measurements for comparison to their other measurements, so I'm not sure it really matters. Personally, I don't follow any pre-determined curve. I started out tuning towards a curve, but quickly realized that I didn't like the sound of those curves and came up with my own curve - and honestly, I don't use a curve at all anymore. I basically just adjust the response to whatever sounds good to _me_. 

I get _extremely_ consistent measurements using the method described above (ear to ear, mic point up). Very quick and easy. I measure each speaker individually, each "pair" of speakers, each "side" and then the entire front (dash, doors and sub). Only takes about 10 minutes to get a complete set of measurements.


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## NIFTY550 (Aug 10, 2020)

GotFrogs said:


> If you're averaging while sitting in the car and waving the microphone around each side of your head, you'll probably require an adjustment to the target. You're going to measure less high frequency with the mic on the far side of your head and more when it's on the near side of your head.
> 
> I have a little array I've used for years that works really well with my target curve (which is the "harman" target curve because I used to work at "Harman". unless they've published something since I left).


I use a 10 minute .wav pink noise file on a USB stick. I sit in the back seat with the drivers headrest removed. I move the mic around in a vertical 6" circle about 10x slowly, positioned approximately where my right ear would be with the mic pointed toward the passenger window. Flip the mic to the left ear position, circle around slowly while pointing to the drivers window. I understand my body and head are not in the drivers seat but I don't think it matters too much. I too get very repeatable measurements. I do my measures, save them, get out of the car, and go sit at the table with my favorite beverage. Play with the EQ filters in REW and load those values into the DSP. Save the DSP file and upload back to the car. Sit, listen, repeat and adjust if required.
P.S. I skip the "beverage" the second time around. Can't have my audio judgement being imparied. Ha!


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## Mauian (Jul 25, 2019)

Ge0 said:


> I was being a smart a$$...
> 
> Ge0


Yep. I know ;-) I was joking along with you. Tough to get that across though with typing sometimes 


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## Ge0 (Jul 23, 2007)

GotFrogs said:


> Just remember if you decide to set up some kind of an array, that the average of the micropohne measurements is not the sum of the measurements. You can't just get a 6 input USB interface and combine the output of the mics. You need software or hardware that provides an average. The spatial average is the average of the MAGNITUDE responses WITHOUT the phase response.


So use Periodic Pink Noise as the stimulus and RTA measurement. The microphones measure magnitude only. Each microphone will produce its own response curve. If I have software average these response curves it should result in the spatial average correct?

Ge0


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## Ge0 (Jul 23, 2007)

Mauian said:


> Yep. I know ;-) I was joking along with you. Tough to get that across though with typing sometimes
> 
> 
> Sent from my iPhone using Tapatalk


I meant I was using my laptop speakers to play the pink noise from my 96kbps .mp3 file 

Ge0


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## Mauian (Jul 25, 2019)

jtrosky said:


> Just as another data point, Helix also recommends the "mic pointing straight up and moving from ear to ear" method of measuring in their Sound Tuning magazines.
> 
> I also take measurements with the MIC pointing up, moving ear to ear and using the 90-degree calibration file - and I use a 20-minutes-long "Lab Grade Pink Noise" track that is in .wav format and played directly from my headunit (stored on a 256gb USB thumb drive that is always installed).
> 
> ...


Totally agree. There is a point where your measurement equipment and process are “good enough” where the minutiae doesn’t matter too much. Also, you bring up a very important point that over time you have to become less restricted by a target curve and learn your tastes and your car. Still, my OCD likes to know the most correct way if there is one, especially if it could have saved me some trial and error and frustration at the beginning wondering why my tune sounded bright when others report that the target curve is pretty flat and not very lively. I’m sure this is a can of worms but hopefully you get what I’m saying.


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## jtrosky (Jul 19, 2019)

NIFTY550 said:


> I use a 10 minute .wav pink noise file on a USB stick. I sit in the back seat with the drivers headrest removed. I move the mic around in a vertical 6" circle about 10x slowly, positioned approximately where my right ear would be with the mic pointed toward the passenger window. Flip the mic to the left ear position, circle around slowly while pointing to the drivers window. I understand my body and head are not in the drivers seat but I don't think it matters too much. I too get very repeatable measurements. *I do my measures, save them, get out of the car, and go sit at the table with my favorite beverage. Play with the EQ filters in REW and load those values into the DSP. Save the DSP file and upload back to the car. Sit, listen, repeat and adjust if required.*
> P.S. I skip the "beverage" the second time around. Can't have my audio judgement being imparied. Ha!


While I measure differently with the MIC (in terms of where you sit, where the MIC is pointing, etc), I also do the bolded/underlined part the same as you. At least until I get it to the point where the tonality is really close and left/right match really well and then I might do a little "final" EQ work while actually in the car (I keep a 7-band EQ defined on each channel and link channels to adjust tonality of left/right at the same time - or make minor adjustments to my 8khz high-shelf filter to get the treble "just right").



Mauian said:


> Totally agree. There is a point where your measurement equipment and process are “good enough” where the minutiae doesn’t matter too much. Also, you bring up a very important point that over time you have to become less restricted by a target curve and learn your tastes and your car. Still, my OCD likes to know the most correct way if there is one, especially if it could have saved me some trial and error and frustration at the beginning wondering why my tune sounded bright when others report that the target curve is pretty flat and not very lively. I’m sure this is a can of worms but hopefully you get what I’m saying.


No, I completely understand what you mean. For me, I just find that the "mic straight up" method makes it easy to get repeatable measurements quickly, so it may not be 100% accurate when compared to others' measurements, but for my uses, it's quick and easy to measure that way and gives me consistent results for comparing changes to my previous tune - even if it's not 100% accurate by "industry standards" (for lack of a better word).  But I get where you are coming from and what you are saying. It's good to do things "the right way" from the start.


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## lingling1337 (Oct 14, 2019)

Mauian said:


> Nice! So you tune your laptop speakers? That must sound wicked
> 
> 
> Sent from my iPhone using Tapatalk





Mauian said:


> Just to throw it out there, I tune with pointing the mic straight up and waving it around my ears with infinite averaging in REW. I think the results are pretty great but I’m always interested in improving...especially if there is good reason to do it another way.
> 
> 
> Sent from my iPhone using Tapatalk


Just FYI you can multi-quote so that you're not double and triple posting.


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## 156546 (Feb 10, 2017)

NIFTY550 said:


> I use a 10 minute .wav pink noise file on a USB stick. I sit in the back seat with the drivers headrest removed. I move the mic around in a vertical 6" circle about 10x slowly, positioned approximately where my right ear would be with the mic pointed toward the passenger window. Flip the mic to the left ear position, circle around slowly while pointing to the drivers window. I understand my body and head are not in the drivers seat but I don't think it matters too much. I too get very repeatable measurements. I do my measures, save them, get out of the car, and go sit at the table with my favorite beverage. Play with the EQ filters in REW and load those values into the DSP. Save the DSP file and upload back to the car. Sit, listen, repeat and adjust if required.
> P.S. I skip the "beverage" the second time around. Can't have my audio judgement being imparied. Ha!



In this scenario there's no need to do the right ear position and the left ear position. Nothing wrong with doing it that way, but it probably isn't contributing any additional accuracy and something like five averages is sufficient. No need for hundreds.


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## Ge0 (Jul 23, 2007)

GotFrogs said:


> In this scenario there's no need to do the right ear position and the left ear position. Nothing wrong with doing it that way, but it probably isn't contributing any additional accuracy and something like five averages is sufficient. No need for hundreds.


I believe his methodology was derived from this video.






Ge0


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## NIFTY550 (Aug 10, 2020)

Ge0 said:


> I believe his methodology was derived from this video.
> 
> Ge0


Yes. That's where I learned about moving mic measurements.


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## AudioGal (Oct 16, 2019)

GotFrogs said:


> The "difference" between the two curves above at 20k is not 0dB, its about 12dB. It appears you've ADDED the two curves rather than subtracting one from the other. For example, 6+(-6) = 0 but 6-(-6) = 12.



The math is correct. The Cal A file has 0db offset at 20k and the Cal B file does not. Unless excel does not do math properly the diff is just Cal a - Cal B that’s all. Just showing they are not the same.


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## AudioGal (Oct 16, 2019)

GotFrogs said:


> Oops. I read the legend incorrectly. Yes. You're right.


Lol i just saw this !!! to funny.


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## AudioGal (Oct 16, 2019)

GotFrogs said:


> Just remember if you decide to set up some kind of an array, that the average of the micropohne measurements is not the sum of the measurements. You can't just get a 6 input USB interface and combine the output of the mics. You need software or hardware that provides an average. The spatial average is the average of the MAGNITUDE responses WITHOUT the phase response.



Yes totally. Although the mic’s do not measure phase directly the measurement technique does because all of the microphones are not equal distance to the sound source As a result the mic’s will see the signal at slightly different times (TDOA) causing a phase offset at the summing junction. Each mic has to be calibrated for the distance to the sound source to sum equally giving a magnitude only response. To not do that creates. a beam former array that is frequency sensitive with a different on axis and off axis response. An impulse response ( delta function) at the beginning of the measurement cycle may help calibrate the mic in real time or an approximation is used based on rules of thumb i suspect.


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## Ge0 (Jul 23, 2007)

NIFTY550 said:


> Yes. That's where I learned about moving mic measurements.


That's where I decided to give it a try too.

Ge0


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## 156546 (Feb 10, 2017)

AudioGal said:


> Yes totally. Although the mic’s do not measure phase directly the measurement technique does because all of the microphones are not equal distance to the sound source As a result the mic’s will see the signal at slightly different times (TDOA) causing a phase offset at the summing junction. Each mic has to be calibrated for the distance to the sound source to sum equally giving a magnitude only response. To not do that creates. a beam former array that is frequency sensitive with a different on axis and off axis response. An impulse response ( delta function) at the beginning of the measurement cycle may help calibrate the mic in real time or an approximation is used based on rules of thumb i suspect.
> 
> Basically, the sum is "What is the combination of all of these mics at the same time" and the spatial average is "what is the combination of all of these mics without respect to time". So, I suppose you could align them all in time very carefully to make T equal or you could just remove T.


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## 156546 (Feb 10, 2017)

No, that still doesn't work because different frequency response has different phase response and that cannot be included in the sum.


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## Ge0 (Jul 23, 2007)

AudioGal said:


> Yes totally. Although the mic’s do not measure phase directly the measurement technique does because all of the microphones are not equal distance to the sound source As a result the mic’s will see the signal at slightly different times (TDOA) causing a phase offset at the summing junction. Each mic has to be calibrated for the distance to the sound source to sum equally giving a magnitude only response. To not do that creates. a beam former array that is frequency sensitive with a different on axis and off axis response. An impulse response ( delta function) at the beginning of the measurement cycle may help calibrate the mic in real time or an approximation is used based on rules of thumb i suspect.


That's why I recommended pink noise. It contains no phase information like impulse response. Pink noise is a pure magnitude measurement. 

I think what Andy is saying is that merely averaging each mics magnitude response is going to negatively impact the resulting phase response.

My head hurts...

Ge0


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## AudioGal (Oct 16, 2019)

Well respectively what explained is a basic delay and sum mic array used for decades. 
The microphones relationship ( distance ) to each other needs to be determined and known. With that a time domain alignment is perfectly doable with in a range of sound source distances. The frequency response may be directly impacted by the microphone spacing and the polar plot of the microphones. All microphones should be matched to some acceptable tolerance otherwise it will be much harder to create a coherent signal


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## THX0849 (Sep 24, 2019)

Stupid question probably but are we supposed to use the foam "cover" on the tip of the microphone. I've got a Umik 1 and in the package it came with a foam piece that goes over the tip. Just wondering, does it help eliminate wind noise while moving the mic around for example?

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## Ge0 (Jul 23, 2007)

THX0849 said:


> Stupid question probably but are we supposed to use the foam "cover" on the tip of the microphone. I've got a Umik 1 and in the package it came with a foam piece that goes over the tip. Just wondering, does it help eliminate wind noise while moving the mic around for example?
> 
> Sent from my HD1905 using Tapatalk


[email protected] How fast are you moving your mic . I'm going to go out on a limb here and say no. The foam piece is supplied to cut down on the affect of wind turbulence. Hopefully you are not creating wind turbulence while waving your mic around. I can picture wild and violent jerky actions .

Ge0


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## Ge0 (Jul 23, 2007)

AudioGal said:


> Well respectively what explained is a basic delay and sum mic array used for decades.
> The microphones relationship ( distance ) to each other needs to be determined and known. With that a time domain alignment is perfectly doable with in a range of sound source distances. The frequency response may be directly impacted by the microphone spacing and the polar plot of the microphones. All microphones should be matched to some acceptable tolerance otherwise it will be much harder to create a coherent signal


So... Mmmm. Ahhhh... No. Just no.

I was going to go there. But its Friday night. I'd rather sit back and have some beer and pizza while watching a Scifi movie with my boys . I'll start thinking again tomorrow.

Ge0


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## THX0849 (Sep 24, 2019)

LOL, no I'm not swinging the mic around like a baton, just wondering if that was it's purpose or not. You've got a vivid imagination! 

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## Ge0 (Jul 23, 2007)

THX0849 said:


> LOL, no I'm not swinging the mic around like a baton, just wondering if that was it's purpose or not. You've got a vivid imagination!
> 
> Sent from my HD1905 using Tapatalk


Thank you 😀. I'm glad I could make you crack up . It kind of lightens the mood around here...

Ge0


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## THX0849 (Sep 24, 2019)

All the high level talk can get a bit much and make you need a break. There are plenty of funny moments and posts on here! You've been the source of a few of them! Hope movie night was a success, pizza and beer is there a better combo!?. Anyways thanks in part to this thread I can better start to do my measurements etc. Thanks!


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## 156546 (Feb 10, 2017)

AudioGal said:


> Well respectively what explained is a basic delay and sum mic array used for decades.
> The microphones relationship ( distance ) to each other needs to be determined and known. With that a time domain alignment is perfectly doable with in a range of sound source distances. The frequency response may be directly impacted by the microphone spacing and the polar plot of the microphones. All microphones should be matched to some acceptable tolerance otherwise it will be much harder to create a coherent signal


That's a beam forming array. That's not what we're after here. We're after a spatial average, which is, essentially, a way to find out "What do I i hear if my head is here, and here, and here, and here and here and here?" None of those can happen at the same time and phase is essentially a representation of the position of each value of a frequency response's position in time. When you time align the microphone's output, you eliminate the flight time variance, but you don't eliminate the rest of the effect of reflections on the phase of each of those measurements. When you add the measurements together (by simply summing the mics), then the phase determines the sum. And that's not a spatial average.


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## THX0849 (Sep 24, 2019)

What version of REW is everyone using? The beta 5.20 or non beta version 5.19? I thought i read somewhere to use the 5.19 instead but not sure now. 

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## jtrosky (Jul 19, 2019)

I use the 5.20 beta - I like some of the newer features that have been added over time.


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## AudioGal (Oct 16, 2019)

GotFrogs said:


> That's a beam forming array. That's not what we're after here. We're after a spatial average, which is, essentially, a way to find out "What do I i hear if my head is here, and here, and here, and here and here and here?" None of those can happen at the same time and phase is essentially a representation of the position of each value of a frequency response's position in time. When you time align the microphone's output, you eliminate the flight time variance, but you don't eliminate the rest of the effect of reflections on the phase of each of those measurements. When you add the measurements together (by simply summing the mics), then the phase determines the sum. And that's not a spatial average.


I understand that. and it is not necessarily required to form or result in a BF array topology which I am going to leave it at that  

Now this 

"but you don't eliminate the rest of the effect of reflections on the phase of each of those measurements. When you add the measurements together (by simply summing the mics), then the phase determines the sum. And that's not a spatial average." 

Is this what you are referring to _conceptually _ http://forums.melaudia.net/attachment.php?aid=22240 and that to have a fulling averaged and phase corrected signal a few steps have to be taken when using separate discrete microphones because the RTA is not doing the averaging in real-time through a single microphone capture session (n samples long)?

Is there commercial software that can do a spatial average in its entirety across multiple discrete microphones without having to do a bunch of steps in quasi real-time? 

This is a very interesting topic on many levels.

I am a believer that the person in the car changes the transfer function of the environment sufficiently and maybe uniquely to an individual  hence I do capture my readings while seated in the drivers seat. using a moving microphone to approximate what and how we/I hear..blah blah blah........ Is there research somewhere that proves or disproves this as a required condition of the measurement or can a suitably altered target curve compensate to a high degree of confidence the absence of a person in the seat, including the effect of reflections created by the legs and lower body, etc.

Everything in a car system including measurements seems to be a collection of compromises and choosing what ever poison we want to live with


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## Ge0 (Jul 23, 2007)

AudioGal said:


> I understand that. and it is not necessarily required to form or result in a BF array topology which I am going to leave it at that
> 
> Now this
> 
> ...


I will argue that you SHOULD be in your car while tuning. You're in your car while listening. If you need to adjust your target curve to compensate then do so.

Ge0


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## THX0849 (Sep 24, 2019)

Ge0 said:


> I will argue that you SHOULD be in your car while tuning. You're in your car while listening. If you need to adjust your target curve to compensate then do so.
> 
> Ge0


Where would you put the laptop? On the pass seat, on your lap, in there back seat while measuring? Wouldn't the laptop also reflect the sound?

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## Ge0 (Jul 23, 2007)

THX0849 said:


> Where would you put the laptop? On the pass seat, on your lap, in there back seat while measuring? Wouldn't the laptop also reflect the sound?
> 
> Sent from my HD1905 using Tapatalk












Ge0


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## THX0849 (Sep 24, 2019)

It's missing the Porsche logo for your Macan

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## bbfoto (Aug 28, 2005)

Well, if you are tuning your car audio system to a "known" target curve, AFAIK none of those targets were _created_ _within a vehicle_, or with someone sitting at the listening position with the microphone(s) (whether in a typical room or a seat within a vehicle), so what exactly are you ''tuning'' TO?

Get the crossovers/phase and Time Arrival right in your system and then EQ to your preference to obtain a SMOOTH & EVEN Magnitude Response. Don't worry so much about _perfectly_ matching a "target curve".

You should be able to HEAR and correct for your body's and HRTF influence.

If you measure with your body in-place, you essentially have no true target to match.

I don't remember or know if the Harman Target Curve for the MS-8 was specifically modified to account for its in-situ headphone microphone measurement system? Andy?


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## Ge0 (Jul 23, 2007)

THX0849 said:


> It's missing the Porsche logo for your Macan
> 
> Sent from my HD1905 using Tapatalk


LOL!!!


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## AudioGal (Oct 16, 2019)

bbfoto said:


> Well, if you are tuning your car audio system to a "known" target curve, AFAIK none of those targets were _created_ _within a vehicle_, or with someone sitting at the listening position with the microphone(s) (whether in a typical room or a seat within a vehicle), so what exactly are you ''tuning'' TO?
> 
> Get the crossovers/phase and Time Arrival right in your system and then EQ to your preference to obtain a SMOOTH & EVEN Magnitude Response. Don't worry so much about _perfectly_ matching a "target curve".
> 
> ...


The setup is a given step in the process to help obtain a desired response at the listening position with repeatable results. To EQ/tune without the basics in place is not beneficial to a repeatable and known quality and qualitative process. 

Well a target curve is just a target to aim for based on a sound preference not a absolute reference for perfection or an anechoic response. If you want a perfectly flat response go for it though 

By tuning in the car the impact of your body presence and mass is taken into account to hit what ever target you are going for. I do not agree the curve becomes irrelevant, based on my experience. The idea is the the human body is a contributing negative factor to hitting the target curve you are going for and should not be ignored. If the center counsel is known to be a problematic reflective surface the lower human body should be contributing as well.

I could see having a target curve for out of car tuning and a different curve for in-car to get a desired similar response. If somebody can point to a high confidence study showing that tuning to an out of car curve that yields a good in car response that sufficiently takes into account the effects of a driver sitting in the car seat to obtain the desired final sound curve great. Please point to it I would love to read up on this stuff.

Or put another way what is the final curve I should expect to measure to sitting in the car after an out of car measurement/tuning session to a target curve that is repeatable across anybody sitting in the seat 

Or is it not just easier to measure to your desired sound curve sitting in the car and then a number of variables are removed.


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## AudioGal (Oct 16, 2019)

Ge0 said:


> View attachment 280461
> 
> 
> Ge0



Sweet .... I just might have to find one in purple!!!


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## Ge0 (Jul 23, 2007)

bbfoto said:


> Well, if you are tuning your car audio system to a "known" target curve, AFAIK none of those targets were _created_ _within a vehicle_, or with someone sitting at the listening position with the microphone(s) (whether in a typical room or a seat within a vehicle), so what exactly are you ''tuning'' TO?
> 
> Get the crossovers/phase and Time Arrival right in your system and then EQ to your preference to obtain a SMOOTH & EVEN Magnitude Response. Don't worry so much about _perfectly_ matching a "target curve".
> 
> ...


Harmans target frequency response curve was derived from the work of an independent contractor named David Clarke from DLC Designs.

Davids method of collecting frequency response data can be found in this AES white paper here:



https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.130.8014&rep=rep1&type=pdf



I knew David and had the chance to contribute towards the development of his Psycho. He was a brilliant guy. It was fun to pick his brain during local audio society events. If you really want to fill your brain with car audio theory just read some of his stuff. 

Ge0


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## 156546 (Feb 10, 2017)

AudioGal said:


> I understand that. and it is not necessarily required to form or result in a BF array topology which I am going to leave it at that
> 
> Now this
> 
> ...


Of course being in the car changes the measurement. If you're going to be in the car, then it will probably be helpful to fully characterize the difference between whatever you use as a target curve for tuning and what you measure when you measure that system while you're in the car. Then, you'll have a target that includes the effect of your body in the car. 

It's simply a matter of correlation.


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## 156546 (Feb 10, 2017)

bbfoto said:


> Well, if you are tuning your car audio system to a "known" target curve, AFAIK none of those targets were _created_ _within a vehicle_, or with someone sitting at the listening position with the microphone(s) (whether in a typical room or a seat within a vehicle), so what exactly are you ''tuning'' TO?
> 
> Get the crossovers/phase and Time Arrival right in your system and then EQ to your preference to obtain a SMOOTH & EVEN Magnitude Response. Don't worry so much about _perfectly_ matching a "target curve".
> 
> ...


All that's really required for a head-mic is a high frequency attenuation of a specific shape. Since we're just measuring the frequency response of a single speaker (or combination of speakers on one side that make up a left or a right), then we aren't in any way attempting to determine the apparent origin of the sound and don't need to account for HRTF for more than that. 

Anyone who's tuning their system thinking that adding a peak or a dip here or there for a different head angle will raise the stage has completely misunderstood what HRTF is for: Moving heads and moving sounds.


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## 156546 (Feb 10, 2017)

Ge0 said:


> Harmans target frequency response curve was derived from the work of an independent contractor named David Clarke from DLC Designs.
> 
> Davids method of collecting frequency response data can be found in this AES white paper here:
> 
> ...


No, the curve you know as the "Harman" curve is one that I used as a retail installer for years and then took with me to Harman when I went to work there. Because I had used it with good success in pleasing customers, it became the curve for MS-8 because at the time, there was no "Harman" curve. 

When the research people discovered that we were working on an autotune for cars, I had to justify this. Since we had a product to finish, I asked that we be allowed to continue while they did their research and if they discovered something else, we would load that curve into the final software. 

So, a few months later they called me in and said, "OK, you're right. We've identified some additional tweaks that people like depending on their preference."

And that's how it became the "Harman" curve.


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## 156546 (Feb 10, 2017)

Ge0 said:


> Harmans target frequency response curve was derived from the work of an independent contractor named David Clarke from DLC Designs.
> 
> Davids method of collecting frequency response data can be found in this AES white paper here:
> 
> ...


Unless you're talking specifically about the development of a PREVIOUS target used primarily by the OE division. Then, David may have played some part.


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## Ge0 (Jul 23, 2007)

GotFrogs said:


> Unless you're talking specifically about the development of a PREVIOUS target used primarily by the OE division. Then, David may have played some part.


Yes, OE division. David collaborated with and was friends with many of the OE suppliers in town. 

Oddly enough many of the target curves are very similar. People are people. A majority prefer a rising bass response and tapering high frequency response. David, Tom Nousaine, Arnold Krueger, Bern Mueller, and David Carlstrom collected data throughout the early 90's with roughly 60+ test subjects to derive their findings. It was a hobby at the time which turned into a business. Other inventions from this crowd include the DUMAX loudspeaker tester and ABX blind comparison tester. Truly a brilliant and really fun crowd to learn from and hang around


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## Ge0 (Jul 23, 2007)

This is somewhat relevant to the conversation. An auto sound competition among OE audio engineers. I'm the idiot with the Black Trailblazer, shorts, baseball hat, and white long sleeve t-shirt. Here, Dave describes the latest iteration of his measurement system as the event starts. I was filming him. This was my first time actually competing in the event which had been going since 1984. Normally I just worked there and observed. It floored me when I heard I had won after making a few simple tweak with my audio control parametric EQ 






The keen will notice two somewhat well known folks in audio who participated in the event. Siegfried Linkwitz (yes, the crossover guy) and Tom Nousaine (journalist and audio enthusiast).

I would have won again in 2007 with my Durango if we hadn't fried my set of brand new Scanspeak Revelator 18W in SPL testing. That threw off spectral balance . On the other hand I did win max undistorted SPL that year by a large margin




__





SMWTMS AUTOSOUND - SEPTEMBER 2007







djcarlst.provide.net





Ge0


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