# Audiofrog Test Gear



## 156546 (Feb 10, 2017)

Testgear now available from Audiofrog. 

Good way to get started making measurements without all the hassle of figuring out what to buy, how to configure it etc. Each microphone is individually calibrated. Works with True RTA, REW and so on and so forth. Also works with Audio Tools and iOS using new devices with the camera adapter.

can't post a link because despite my million previous posts, I haven't posted often enough to include a link. 

testgear dot audiofrog dot com


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## karmajack (May 9, 2017)

Audiofrog UMI-1 – USB Measurement Interface Kit

USB Measurement Interface

You’ve spent hours—maybe even days or weeks—planning and installing your system. Don’t leave the final performance to chance. Tuning by ear is often a frustrating process of turning dials and moving sliders in your DSP only to decide that what you’ve just done stinks. Stop guessing!

Audiofrog’s new USB Measurement Interface is a complete microphone kit designed to work with most PCs, Macs and tablets that include a USB port. The UMI-1 is suitable for use with most acoustic measurement and analysis software including Room EQ Wizard (REW), True RTA, Holm Impulse, ARTA and others. The adjustable microphone stand is designed to mount easily to the car’s headrest using a Velcro® strap and places the microphone in the ideal location for real time frequency response measurement and analysis. The TM-1 omnidirectional microphone provides response from 20 Hz to 20 kHz. A separate calibration file for each serialized microphone is available from Audiofrog.

$199

UMI-1 Kit Includes:

6 mm Omnidirectional Measurement Microphone with Calibration File
USB Sound Card with Mic Input and Stereo Line Output
Microphone Stand with Integrated Extension Cable
3.5mm Stereo to RCA Adapter
3.5mm Male to Male Adapter
Velcro Headrest Strap
Extension Cable
Carrying Case
Test CD


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## Justin Zazzi (May 28, 2012)

Isn't making a spatial average the best method for this? And if so, then why did you develop a single microphone that is designed to be anchored to a single point, specifically so it cannot be moved for a spatial average? After being a part of the MS-8 project which used six unique microphone locations (moving your head left and right and center), I'm really confused why you decided to go this way.

What's up with that?


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## t3sn4f2 (Jan 3, 2007)

Jazzi said:


> Isn't making a spatial average the best method for this? And if so, then why did you develop a single microphone that is designed to be anchored to a single point, specifically so it cannot be moved for a spatial average? After being a part of the MS-8 project which used six unique microphone locations (moving your head left and right and center), I'm really confused why you decided to go this way.
> 
> What's up with that?


Looks like the Velcro strap and pivot mount was chosen to allow for multiple mic locations. For those that want to have more than one measurement point.


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## bbfoto (Aug 28, 2005)

And use one of these inexpensive mannequin heads for "Head Shadowing" measurements. There's also canvas-covered cork heads for more realistic absorption properties.  




















Female-Professional-Cosmetology-Mannequin-Head-AMAZON


.


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## 156546 (Feb 10, 2017)

Jazzi said:


> Isn't making a spatial average the best method for this? And if so, then why did you develop a single microphone that is designed to be anchored to a single point, specifically so it cannot be moved for a spatial average? After being a part of the MS-8 project which used six unique microphone locations (moving your head left and right and center), I'm really confused why you decided to go this way.
> 
> What's up with that?



Stay tuned. 

FWIW, after MS-8, we determined that a spectral average was about 90% as accurate as a spatial average and, therefore, MS-2 used only a single mic measurement. The downside of a spatial average is that there's no phase data, so both measurements are important. A spatial average is helpful above 1k, but below 1k it isn't all that useful.


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## 156546 (Feb 10, 2017)

bbfoto said:


> And use one of these inexpensive mannequin heads for "Head Shadowing" measurements. There's also canvas-covered cork heads for more realistic absorption properties.
> 
> 
> 
> ...



Why is a head measurement necessary? That just requires one to come up with a new target curve to account for masking at high frequencies.


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## drop1 (Jul 26, 2015)

Kinda reminds me of when i used to bend up coat hangers to place the pioneer auto eq mic exactly where the center of my head would be. That evolved into balling up towels and eventually me just sitting in the car with the mic clipped to the front of my sun glasses.

Any reason to buy these over say a umik1 for use in REW?
not nit picking , just asking.

Really like your speakers my entire system is frog gb series. Subs are stellar!

I have a question my dealer couldn't answer. 
I need an 8" or so bone frog sticker. Does such a thing exist ?


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## Niick (Jun 3, 2015)

GotFrogs said:


> Stay tuned.
> 
> FWIW, after MS-8, we determined that a spectral average was about 90% as accurate as a spatial average and, therefore, MS-2 used only a single mic measurement. The downside of a spatial average is that there's no phase data, so both measurements are important. A spatial average is helpful above 1k, but below 1k it isn't all that useful.


Can you elaborate a bit on the term "spectral average"? 

By this I'm assuming you're referring to a temporal average of a single microphone? 

Or no?


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## bbfoto (Aug 28, 2005)

GotFrogs said:


> Why is a head measurement necessary? That just requires one to come up with a new target curve to account for masking at high frequencies.


I guess I used the wrong Smiley in my post.


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## Elgrosso (Jun 15, 2013)

drop1 said:


> ...
> 
> Any reason to buy these over say a umik1 for use in REW?
> not nit picking , just asking.
> ...


One of the many reasons I got it is the size...
Umik is not that big, but measuring the power response in different spots at the right angle with the laptop on the knees, steering, cables etc was always tricky, especially if I want to use the same exact points for a before/after EQ.
I didn't try it in car yet as I don't have the car right now, but with this size it should be much more comfortable and easy.

Related good point that Andy explained, it’s not directional, mic is so small that response is the same at all angles.
Kind of cool to not have to worry about which cal file to use when you mix positions.

And last, it’s AF, great company, great guys, bunch of accessories, and I’m sure to get great support if needed (it's already the case).


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## 156546 (Feb 10, 2017)

Niick said:


> Can you elaborate a bit on the term "spectral average"?
> 
> By this I'm assuming you're referring to a temporal average of a single microphone?
> 
> Or no?


I mean smoothing. I now use a single mic (because I lent my array to someone) and I use 1/3rd octave above 3k, 1/6 between 800 and 3k, and 12th below that. I think you can also do frequency dependent smoothing in REW if you make sweeps.


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## ErinH (Feb 14, 2007)

REW also has "psychoacoustic" smoothing as well. Which I find interesting how the bins are broken up. 

https://www.roomeqwizard.com/help/help_en-GB/html/graph.html


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## Niick (Jun 3, 2015)

GotFrogs said:


> Niick said:
> 
> 
> > Can you elaborate a bit on the term "spectral average"?
> ...


Gotcha.

So, in Smaart v8, you retain phase with spatial averaging. I made a couple short videos showing the difference between multiple mics and one mic. Sometimes those differences are bigger than other times. 

The videos are uploading now. They aren't exciting. But they might be kinda interesting, I guess. 

I'll post links as soon as they're done.


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## Mlarson67 (Jan 9, 2015)

When can we expect a frog dsp to use this thing with?


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## Niick (Jun 3, 2015)

here's a couple real quick videos showing multi mic spatial averaging vs. a single mic, this is but one car, but one scenario.

Draw your own conclusions.

https://youtu.be/EaiixbDhgBY

https://youtu.be/zZBFBPmNqbc


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## 156546 (Feb 10, 2017)

Niick said:


> here's a couple real quick videos showing multi mic spatial averaging vs. a single mic, this is but one car, but one scenario.
> 
> Draw your own conclusions.
> 
> ...


I just spent an hour typing a response to this only to be informed that I took too long and my session timed out. I'm not doing that again. 

Ive googled and googled and cannot find adequate documentation for how SMAART is calculating average phase. That makes a big difference. If it's a simple average (and I can't tell from the video), how is that useful? If I have two speakers and I measure one at -180 and one at 0 at 200Hz, the average at 200 Hz is -90. If I have the same two speakers and I measure one at -90 ad one at +90, then the average is zero. In both cases, the sum is -180 and there's a null.


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## Niick (Jun 3, 2015)

Ill make ya a video answering ALL points 

Might take me a bit, just got to the shop today, gonna be real busy, probably wont be till after work.


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## 156546 (Feb 10, 2017)

The fact that there's no AVERAGE IMPULSE RESPONSE is instructive. 

In some of the products I've helped to develop in a past life that provide an auto EQ, the EQ has to have a phase curve on which to base its correction, so a minimum phase curve was generated from the spatial average. That has pros and cons. The pro is that corresponds to the frequency response measurements. The con is that it doesn't expose areas where the behavior isn't near minimum phase. That requires that the Auto EQ protect itself from that error. Since those errors are often an attempt to boost in a null, setting a maximum Q value and maximum boost value for the EQ helps to weed those out.


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## Elgrosso (Jun 15, 2013)

GotFrogs said:


> The fact that there's no AVERAGE IMPULSE RESPONSE is instructive.
> 
> In some of the products I've helped to develop in a past life that provide an auto EQ, the EQ has to have a phase curve on which to base its correction, so a minimum phase curve was generated from the spatial average. That has pros and cons. The pro is that corresponds to the frequency response measurements. The con is that it doesn't expose areas where the behavior isn't near minimum phase. That requires that the Auto EQ protect itself from that error. Since those errors are often an attempt to boost in a null, setting a maximum Q value and maximum boost value for the EQ helps to weed those out.


Do you think possible for an autoEQ to use some sort of contextual/adaptive averaging method?
I mean using different weight law based on measurements similarities.
Like not using the best and worst case with crazy phase response, and average the most common only.

I ask because I wondered for a while how APL workshop and Dirac are working in the background.
Both have a different approach, but very similar results.
APL will use 200+ sweeps everywhere in the cabin (with some limitations).
When Dirac uses 9 per side only, it's left to the user to decide which points to use.

My hypothesizes:
- APL doesn't prioritize anything, so I expect it to just average them all.
But in a way, the big amount of measurements mitigate the weight of the worst cases, since the system needs to be somewhat pre-tuned.
- Dirac that also applies TA based on the 1st sweep, will give more weight to it compared to all others.
Maybe it even applies its IR correction with a big bias on the 1st measurement, and its FR correction on the average of 9.


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## Niick (Jun 3, 2015)

Making video now.

Elgrosso, your idea of averaging the "most common" only is actually a really Smaart idea 

Ill show ya that in the video too.

See next post


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## Velozity (Jul 6, 2007)

Nice measurement system here Andy. I'm content with my UMIK-1 but I believe I'll give Testgear a try. I really like the velcro idea. The mounting possibilities are endless. Are there particular benefits of the outboard USB soundcard with 3.5mm mic input versus a standard USB microphone?


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## 156546 (Feb 10, 2017)

Velozity said:


> Nice measurement system here Andy. I'm content with my UMIK-1 but I believe I'll give Testgear a try. I really like the velcro idea. The mounting possibilities are endless. Are there particular benefits of the outboard USB soundcard with 3.5mm mic input versus a standard USB microphone?


Stereo audio output so you can use the PC to generate the test signal. It only has one audio (mic) input, so no loopback is possible, but you can use one output channel to drive the nearest tweeter and use it as an acoustic reference in REW. 

I'll have to post some instructions for doing this, but it's a valid way to make impulse response measurements that include flight time and actual phase without that loop. 

I'm also thinking about making a small speaker that can attach to the mic stand that's powered and could serve as that acoustic reference.

We'll also have a second kit that's a USB audio interface with phantom power and balanced inputs that will be useful for electrical measurements. That kit will come with an adapter that will allow the phantom power in the interface to power the UMI-1. That's probably a couple of months out or so.


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## 156546 (Feb 10, 2017)

Elgrosso said:


> Do you think possible for an autoEQ to use some sort of contextual/adaptive averaging method?
> I mean using different weight law based on measurements similarities.
> Like not using the best and worst case with crazy phase response, and average the most common only.
> 
> ...


Sure. MS-8 also used the first measurement to set delays and the other measurements to correct the frequency response. It works by making 6 impulse response measurements, aligning them, converting each of them to frequency response measurement through FFT, averaging them, calculating a minimum phase for the average, converting that back into an impulse (IFFT) and applying EQ (8 bands) on the impulse response because that allows a single EQ band to invert nearly any shape, and then convolving that with the audio signal. The way that those EQ bands are distributed is similar to "frequency dependent averaging".


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## Niick (Jun 3, 2015)

Elgrosso said:


> GotFrogs said:
> 
> 
> > The fact that there's no AVERAGE IMPULSE RESPONSE is instructive.
> ...


Andy, 

The videos are uploading. 

Elgrosso,* in Smaart, a feature called "coherence weighted averaging" does something very much like your idea of averaging the "more similar" parts of the individual responses. 

As for weighting the average based on the first sweep as opposed to the other sweeps: 

That's, in my opinion, kinda the beauty of software like SysTune, for example, you have real time impulse response, using whatever stimulus you like, be it music, pink noise, log sweeps, whatever. 

But then you also have, simultaneously, a power averaged magnitude response, based on up to 8 live microphones. Now, being that it's a power average, you can simply put, say, 6dB (or any level) greater weight, on any one mic, into your resulting average by simply increasing the level of that mic +6dB over the other contributors. 

That's one aspect of what's referred to as "power averaging", the measurement with the highest energy, contributes the greatest amount of weighting in its favor into whatever average its a part of. 

Now, dB averaging is different. With dB averaging, the level of any one mic (or sweep, these averages can be either live or with static traces) does not change the shape of the resulting average, it only has an effect on resulting average's level on the graph. 

You bring up an interesting point about the APL1 and the 9 point Dirac. 
The other day I was tuning a car, and, after completing a driver's seat preset, I reconfigured my 7 mic array to allow me to do a 2 seat tuning. I put 3 mics in drivers seat, 3 in passenger, and 1 mic between the seats. 

The resulting spatial average of the "two seat setup" was surprisingly similar to the single seat configuration of the mics.

Edit : I go into onto a bit of detail regarding coherence weighted averaging in the videos, they're currently uploading.


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## Jscoyne2 (Oct 29, 2014)

Its like all the smart kids in the front of the class having a conversation with the teacher about the complicated side of a simple idea. 

I was always the kid in the back, understanding half of it and drawing some doodles.

Continue on.


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## 156546 (Feb 10, 2017)

Jscoyne2 said:


> Its like all the smart kids in the front of the class having a conversation with the teacher about the complicated side of a simple idea.
> 
> I was always the kid in the back, understanding half of it and drawing some doodles.
> 
> Continue on.


The point at which you get it and it becomes useful to you is the point at which the rest of us have done our jobs. Complexity isn't useful until it can be communicated in a way that's simple and being able to communicate it in simple terms is evidence that the person doing the communicating actually understands what they're doing. 

Tuning one seat cars is simple. The frequency response of the left and right speakers should be closely matched at the listening position and the sound from both (and from the sub) should arrive at the listening position in phase. That's it. Tools that contribute to one's ability to achieve that are useful. 

The spatial average is useful because it makes the display of the frequency response better correlate with what we hear. It eliminates the narrow peaks and dips that are the result of the direct sound mixing with the reflections that we don't hear because we constantly move our heads. Those peaks and dips appear in a single mic measurement. It's useful for frequency response tuning at high frequencies. It is not useful for determining the phase relationship between speakers because there is no phase response in the average. Generating a phase response for the average is sometimes necessary for an auto tune to do its job, but whatever phase response is generated is an APPROXIMATION. That approximation can be useful for some things but provide a goose chase for other aspects of tuning the car. 

Phase response at high frequencies isn't nearly as important as is it is below 1k. Because wavelengths at lower frequencies are longer, the spatial average in a car becomes less useful. You can see that easily in Nick's videos--as frequency is reduced, the average becomes much more similar to each of the single mic responses, which are more similar to each other. 

In order for a stereo system to work properly, it has to be tuned correctly. Ultimately, that's determined by the acumen of the person doing the tuning rather than the tools.


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## ErinH (Feb 14, 2007)

My process for tuning via mic is a single mic location up to about 600hz with a gradual "weight" of use for averaging increasing in frequency until about 10khz. As Andy noted a single mic permits phase analysis and cars are typically minimum phase until around 400-500hz where you transition from an area of pressure based response to an area where reflections dominate the response. This range below 1khz happens to be an area where bearing is more sensitive to phase. Above that you're trading intensity differences which is why I prefer to sweep the mic while recording and collect an "average" response and base any DSP adjustements to correct the response on this average, again, with more weight given to the results the higher in frequency I go. 

I don't say that to say it's the best method. But it follows, at least to me, a logical thought process using my understanding of phase vs intensity impacts and how those can be applied in a car. This makes tuning simple when you're looking to correct the response below that transition period I mentioned above because you are in a modal (pressure) based response segment and can take advantage of the minimum phase measurements while relying on an average (again, I'm sweeping the mic) the higher in frequency you go. 


Side note: regarding a given target curve: I don't see anyone mention the shape of the measurement rig and how that influences the response. For example, even a simple stand mounted mic will have a reflection from the stand itself. If you have a target curve, it would seem to me this curve should also account for the effect of the mic stand/apparatus via some compensation curve. Especially if it's a very complex one like Niick is using. Then you factor in the complexity of different headrest shapes and materials and those (non-trivially) will impact the measured response. I'm sure some will say "but it's a car, it's close enough" to which I would reference you back to your target curve. If you're using a target curve but the measurement rig causes a 6dB dip and combing pattern of peaks/dips starting at 7khz are you going to try to correct the system response on that result, not realizing it's the rig that's causing these issues?
Here's a link for example:
Loudspeaker Measurements

These things can't be windowed out, either. The time would be too large. To me it's an interesting aspect. And it's a legitimate concern. Though, admittedly I don't have a solution other than finding some way to quantify the apparatus' effect.


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## 156546 (Feb 10, 2017)

ErinH said:


> My process for tuning via mic is a single mic location up to about 600hz with a gradual "weight" of use for averaging increasing in frequency until about 10khz. As Andy noted a single mic permits phase analysis and cars are typically minimum phase until around 400-500hz where you transition from an area of pressure based response to an area where reflections dominate the response. This range below 1khz happens to be an area where bearing is more sensitive to phase. Above that you're trading intensity differences which is why I prefer to sweep the mic while recording and collect an "average" response and base any DSP adjustements to correct the response on this average, again, with more weight given to the results the higher in frequency I go.
> 
> I don't say that to say it's the best method. But it follows, at least to me, a logical thought process using my understanding of phase vs intensity impacts and how those can be applied in a car. This makes tuning simple when you're looking to correct the response below that transition period I mentioned above because you are in a modal (pressure) based response segment and can take advantage of the minimum phase measurements while relying on an average (again, I'm sweeping the mic) the higher in frequency you go.
> 
> ...


Right, in the example of the piece of cardboard placed near the mic, a comb filter is created. Clearly, some smoothing would remove the comb from the display and the smoothed measurement would closely correlate with the measurement that didn't include the cardboard. 

The question is "How closely does the measurement correlate with what I hear and if it doesn't, can I make some reasonable adjustments in the rig on in my perception of that correlation for the measurement to be useful? "

In my case, I'd say that the cardboard doesn't invalidate the measurement for ME. If I thought that those peaks and dips should be equalized because I didn't understand what caused them, then they would invalidate the measurement. But the fact that they invalidate the measurement would be based on my lack of acumen, not on the cardboard.


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## Babs (Jul 6, 2007)

GotFrogs said:


> Sure. MS-8 also used the first measurement to set delays and the other measurements to correct the frequency response. It works by making 6 impulse response measurements, aligning them, converting each of them to frequency response measurement through FFT, averaging them, calculating a minimum phase for the average, converting that back into an impulse (IFFT) and applying EQ (8 bands) on the impulse response because that allows a single EQ band to invert nearly any shape, and then convolving that with the audio signal. The way that those EQ bands are distributed is similar to "frequency dependent averaging".


Sounds like why folks were like "when when when will it be out?" while you were killin' it working on making that thing as good as it could be. Was/is certainly ahead of it's time and was an awesome piece.


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## 156546 (Feb 10, 2017)

Babs said:


> Sounds like why folks were like "when when when will it be out?" while you were killin' it working on making that thing as good as it could be. Was/is certainly ahead of it's time and was an awesome piece.


I didn't design the auto EQ. That was Ulrich Horbach.


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## Niick (Jun 3, 2015)

K, the videos are finally done. 

I 100% agree with Andy that the quality of the end result of ANY proves depends heavily upon the dedication, skill, commitment, experience, and focus of he who is doing the work. 

That being being said, you dont see guys at car audio shops using hand saws, hand drills, and or any other old world woodworking tools to build subwoofer enclosures and or any other fabrication. Rather, new, modern, efficient tools are put to use. CNC machines are becoming common. 

Working with acoustics, audio, tuning... It's no different. 

Modern, efficient tools in the hands of a person who is passionate about their craft will carry that person farther than old, inefficient practices will. 

Makes no difference what we're talking about. 

https://youtu.be/FenV4qnuU-k

https://youtu.be/pvPCkpxRYIQ


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## Elgrosso (Jun 15, 2013)

GotFrogs said:


> Sure. MS-8 also used the first measurement to set delays and the other measurements to correct the frequency response. It works by making 6 impulse response measurements, aligning them, converting each of them to frequency response measurement through FFT, averaging them, calculating a minimum phase for the average, converting that back into an impulse (IFFT) and applying EQ (8 bands) on the impulse response because that allows a single EQ band to invert nearly any shape, and then convolving that with the audio signal. The way that those EQ bands are distributed is similar to "frequency dependent averaging".


Thanks for these details, I'm not sure you ever gave them here (maybe).
Was there any specific way to average these 6 sweeps or did they all have the same weight?
I always wondered if both side mics were recording the same sweep, apparently not since you said 6 sweeps in total, not 12.
I played a lot with it, with all kind of positions for the mics etc, it was fun.

The reason you went with a headset mic at that time, was for convenience/cost issues or really for more conceptual reasons?
I mean between a potentially larger area with a hand mic VS head area only with a headset (much more practical for the targeted user).






Niick said:


> Andy,
> 
> The videos are uploading.
> 
> ...



Very interesting Niick thank you.
So we can say every time you add 6db to one curve, you double its impact on the final average?
That's something we could artificially re-create, if ever needed, just by increasing volume level in some spots when we move our mic
(for folks with more basic tools like me).

About APL I see what you mean, I was very surprised too when I first saw this kind of result.
I mean at some point, adding more sweeps in different spots would have very little impact on the final averaged response.
Of course I'm not talking about making seeps in the glove box or under the seat , but large area from roof to seat, glass to glass etc.
It seemed unreal to me at first but apparently it's logical, more points > less weight per point.
And a good system should have most of its energy in the middle of the car anyway.

But, this was not always the case, it depended a lot on the pre-tune.
I expect this to be related to the global power response, more beaming more holes etc
And that's where I am right now, focusing on the power response when I pre-tune, I kind of dropped the around the head idea.
And with the horns it’s kind of fun since there’s also their high directivity to account for.
(not saying I fully understand all these concepts but so far so good ).


For reference, the points map for the APL:
in yellow those to avoid because too close of the drivers (if they're here)


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## josby (May 8, 2011)

GotFrogs said:


> Sure. MS-8 also used the first measurement to set delays and the other measurements to correct the frequency response.


Do you think there'd be value in buying a UMI-1 to confirm one's MS-8 is achieving its target curve? And if so, how much will the center and rears complicate the process of using this?


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## cmusic (Nov 16, 2006)

While I completely agree that acoustical measurement equipment has gotten much better and more accessible over the years, still the overall determination of sound quality it still the human ear. I've heard many a system that looked really impressive on the graphs produced by the latest audio measurement software that sounded like crap when listened to. A system can have perfect graphs and even score high in competition and still not sound good. It's great to have all this new acoustical measurement technology to get a system partially dialed in but my hearing will put the finishing touches on the sound tuning. 

That said, how many people actually knows what good sound is? I've seen IASCA competition judges rip a system's tonality apart because it did not sound correct. BTW the judge in question actually played in the orchestra on the track used on the IASCA CD, so he should have a pretty good idea of what the track should have sounded like. 

I've been the head audio system tech at my church for almost 20 years and I hear several live acoustical performances every service I'm over. If something is off in my church's sound system I have to immediately know how to correct it to make the performance sound natural. I have to make the sound system seem invisible to the people attending the service. I know what to adjust when someone sounds nasally or has too much symbalance. If I don't get the sound right then it could (and has in the past) disturbed the service. When training my helpers, the hardest thing I teach them is to get them to learn how to hear correctly, recognize when something in the sound is wrong, and what to do to correct it. In turn this has helped me learn on how to tune by ear rather than rely on electronic measuring equipment. 

Years ago there was a show in southern Georgia called the Perry Invitational. It was similar to today's Augieland Invitational and Steel Valley Regionals. It was held at a fairground with many large buildings. Besides the main judging hall, many other other buildings were rented out to manufactures for competitors on their teams and using their equipment. At the time I was using Kicker equipment and in their building Mark Eldridge set up a listening station consisting of a pair of Stax head phones, a head phone amp, and a high end CD player. Listening to the judging CD, one could really hear what each track should sound like tonally. 20 years later I use a pair of Grado headphones to listen to the music in my car for a tonal reference. Mark also had a Kicker 12" sub in a sealed enclosure and two pro studio monitors powered by Kicker car amps (using a battery and a 12V power supply) and an Adcom home CD player. The equipment was arranged on a thick carpet rug with a chair at one end. It was set up like a high end two channel home audio system. Listening to both setups really helped me understand what music should really sound like. 

Again, all of these technical measurements is great if used correctly, but always trust your ears first.


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## 156546 (Feb 10, 2017)

Elgrosso said:


> Thanks for these details, I'm not sure you ever gave them here (maybe).
> 
> 
> Was there any specific way to average these 6 sweeps or did they all have the same weight?
> ...


We chose wearable mics so that the user could make measurements while he operated the remote control and looked at the display. Three sweeps times 2 mics is six measurements per speaker location for frequency response measurements. One sweep for each channel times two mics for delay. 

Why would it be helpful to make measurements in locations in a car that have nothing to do with the listening positions? Adding the frequency response measured at the apex of the windshield, a-pillar and dashboard and a bunch of other locations in which no one would ever listen would simply provide a lower weighting to locations that matter and serve to invalidate the measurements if optimizing for listening positions is the objective.

Oh, and your tweeter is blown. I'll send you a replacement.


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## 156546 (Feb 10, 2017)

josby said:


> Do you think there'd be value in buying a UMI-1 to confirm one's MS-8 is achieving its target curve? And if so, how much will the center and rears complicate the process of using this?


A single mic measurement isn't going to correlate very well to what MS-8 does., but making a few measurements and averaging them will confirm.


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## 156546 (Feb 10, 2017)

cmusic said:


> While I completely agree that acoustical measurement equipment has gotten much better and more accessible over the years, still the overall determination of sound quality it still the human ear. I've heard many a system that looked really impressive on the graphs produced by the latest audio measurement software that sounded like crap when listened to. A system can have perfect graphs and even score high in competition and still not sound good. It's great to have all this new acoustical measurement technology to get a system partially dialed in but my hearing will put the finishing touches on the sound tuning.
> 
> That said, how many people actually knows what good sound is? I've seen IASCA competition judges rip a system's tonality apart because it did not sound correct. BTW the judge in question actually played in the orchestra on the track used on the IASCA CD, so he should have a pretty good idea of what the track should have sounded like.
> 
> ...


I agree with most of this, but when I'm tuning, I NEVER listen until the measurements indicate it's worth listening to.


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## Elgrosso (Jun 15, 2013)

GotFrogs said:


> ...Why would it be helpful to make measurements in locations in a car that have nothing to do with the listening positions? Adding the frequency response measured at the apex of the windshield, a-pillar and dashboard and a bunch of other locations in which no one would ever listen would simply provide a lower weighting to locations that matter and serve to invalidate the measurements if optimizing for listening positions is the objective.
> 
> Oh, and your tweeter is blown. I'll send you a replacement.



I don't know! That's what I'd like to understand.
Well first thanks for taking some time here.
I'd imagine you're one of the few that could explain, that's why I brought it up.
I don't use the APL anymore this was maybe a year ago, now it's dirac.
But with APL I always followed Raimonds' guidelines and had very good results (like many others here now).

Good results compared to what I could do manually only, so yeah I'm certainly the weakest link here.
Knowing that both apl and driac need a system with an ok tune at the minimum.
They just add the final touch, but a touch that makes everything more coherent.
(I did some Blind tests with the apl, someone else toggling the switch for me, and it was really obvious. Can't technically do the same with dirac)

I'm just guessing but maybe measuring these extreme areas is a way to detect the worst part of the system.
And if the algo "knows" the worst it automatically "knows" the best, and can give it more weight, or use these informations in some way for the final filter.
Silly?

Now with dirac the area I mostly use is:



Sometime sofa/both seats, but I usually come back to this chair.
I use this "cube" first because dirac is designed around that (although not for cars).
And also because I just get the best results like that, compared to a much smaller volume near the head or even just one point for all 9 sweeps.

Here too I try to understand.
Adapting and getting a good pre-tune for such a large volume bring the needs for slightly different XO, and softer EQ. So maybe here is the real difference.
The final average response is «*to target*» for these 9 pts, but certainly not at the ears.
But I don’t care it just sound better to me than when I was using head points only. (Hanatsu’s method, ms8 like, rta, etc)
Or maybe it's only the corrections they both do in the time domain, that are wonderful. And I don’t know how to do that manually myself, yet.


Edit: 
And what's with this tweeter thing? I’ve never blown an Audiofrog tweeter and I tried hard! 
Probably not me, I’m David... dirac, recent emails, umi-1 etc


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## 156546 (Feb 10, 2017)

Elgrosso said:


> I don't know! That's what I'd like to understand.
> Well first thanks for taking some time here.
> I'd imagine you're one of the few that could explain, that's why I brought it up.
> I don't use the APL anymore this was maybe a year ago, now it's dirac.
> ...


Yeah, oops. Wrong David.


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## Elgrosso (Jun 15, 2013)

Niick said:


> K, the videos are finally done.
> 
> I 100% agree with Andy that the quality of the end result of ANY proves depends heavily upon the dedication, skill, commitment, experience, and focus of he who is doing the work.
> 
> ...


Really cool these videos Niick. They worth being watched multiple times! Thanks for taking the time here too.
That's the perfect illustration of what I had in mind, although much more complex.
Don't know this soft but I believe I grabbed a little of the idea, and it's very nice to see someone mastering a soft like that.
Do you hold the cam in left hand or attached to your head? Because I imagine with keyboard shortcuts it could be a real fast process.

Quick question, based on your experience of many many cabins and setups:
Did you see big differences in term of, don't know how to say better, phase gaps between all mics of your array, for all different driver layouts?
In other words, the phase here in the video seems to vary really smoothly and regularly between each independent mic, almost predictable.
Is this difference highly dependent of the driver layout? I would certainly imagine so, but how much?
Like between popular on dash VS horns VS in door VS kicks etc.
Which one in your view has the most regular, or gradual, phase shift on your array?

Simpler, which driver layout has the most consistent phase shift on your 7 mics? (horizontal placement?)
I don't know if the question makes sense, it makes in my head though


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## Niick (Jun 3, 2015)

Elgrosso said:


> Do you hold the cam in left hand or attached to your head? Because I imagine with keyboard shortcuts it could be a real fast process.


 Yes, in those videos I am holding the camera with one hand, and yeah, when I'm "in the zone" the process is very fast.

I'd like to say something real quick before I continue with topics of multi-mic, phase, averages, etc. 

After talking with Andy, I've really come to realize where it is that i might want to put my efforts,as far as career/business model. I'd like to make clear that a lot of what we're talking about is "deep down the rabbit hole" stuff, as Scott Welch once put it. 

I think that the Audiofrog measurement system is great for folks that are either wanting to get into tuning car sound systems, or, as is very often the case with shops/installers, they're NEEDING to start learning this stuff, whether they like it or not, because its a part of the new reality of working in car audio, working with modern cars. 

I wish something like this existed when I was getting started learning this stuff. For me, it was out of necessity that I began learning, and I found that it fit me well, and I've ran with it, the way many guys run with fabrication skills. 

So yeah, a lot of what we're talking about is stuff that someone might wonder about or attempt to figure out AFTER they've gotten comfortable with the basics. After they've developed a solid foundation upon which to experiment and attempt to refine their own understanding and their own methodology/workflow. 

But it's that solid foundation that has to be developed first, and I believe that Andy is a great teacher for those who are trying/needing to do just that. 



Elgrosso said:


> Quick question, based on your experience of many many cabins and setups:
> Did you see big differences in term of, don't know how to say better, phase gaps between all mics of your array, for all different driver layouts?
> In other words, the phase here in the video seems to vary really smoothly and regularly between each independent mic, almost predictable.
> Is this difference highly dependent of the driver layout?


 Yes, the driver layout/positioning/aiming does have a significant effect on the resulting "measure-abilty" of the phase, and, in general, I have noticed that "better" speaker positioning results in smaller differences between mic locations.

Now, that's just a very generalized statement though. I've set up an experiment where I can simulate the effects of reflections on the measured response, by comparing, in real time, a speaker measured on a large baffle to that same speaker in a car. I then add "reflections" using DSP (delayed copies of the measure signal, each copy with slightly more delay, and each copy with slightly less energy), I'll post a link to this video, I dont think I've posted this one on the forum before, If I have I apologize. But I dont think so, because when I made this video it was just to show a friend of mine the proof of concept, and I've made significant advancements since then in my understanding, and in the experiment itself. 

Again, let me state that this next video is purely an exercise in me trying to gain a deeper, more intuitive understanding of exactly how/why the acoustic environment effects the measured response the way it does. This is just spare time, stuff i do for fun. Nothing concrete, nothing carved in stone here, Im just playing around here in this video 

https://youtu.be/PlZ8jB6GgaI


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## Elgrosso (Jun 15, 2013)

Nice exercise again!
The simulation gets really close, in both amplitude and phase.
Did you try to apply and re-measure these «*reflections*» in live to a baffle driver? 

Do you think you could define a bunch of filters that would simulate the entire cabin interactions? Almost like testing/tuning the car with all drivers still outsides 

And how did you decide the delay for each cascade filter, were they based on some basic in car measurements? (like driver to opposite door or glass etc)


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## Niick (Jun 3, 2015)

Elgrosso said:


> Nice exercise again!
> The simulation gets really close, in both amplitude and phase.
> Did you try to apply and re-measure these «*reflections*» in live to a baffle driver?
> 
> ...


I think that defining a bunch of filters that COMPLETELY simulates a vehicles interior would require more skill, and possibly more computing power, than I currently possess.

This exercise has taught me that the major features can be modeled/induced with just simple minimum phase filtered delayed copies of the original signal. 

As far as how I determined the attenuation level and delay time of each successive copy...... Pure guessing. Trial and error. As I said, I was purely just playing around to see if it would work. 

It worked  

I think I'd like to start a new thread, to continue on with these types of topics/discussions. 

I think I originally found this thread from an email.....? 

Anyways, I never intentionally meant to "hijack" Andy's thread. But it seems I have. 

I apologize for that. Sometimes I get caught up with technical concepts and forget to look at the "how did this conversation even begin in the first place" aspect of things. Which, I've learned, is a type of "forum etiquette" that I'm guilty of having been blind to in the past. 

The first step is admitting you have a problem....


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## Elgrosso (Jun 15, 2013)

Niick said:


> Anyways, I never intentionally meant to "hijack" Andy's thread. But it seems I have.
> 
> I apologize for that. Sometimes I get caught up with technical concepts and forget to look at the "how did this conversation even begin in the first place" aspect of things. Which, I've learned, is a type of "forum etiquette" that I'm guilty of having been blind to in the past.
> 
> The first step is admitting you have a problem....


I'm faulty too, it started somewhat related with one point VS multi points but is not so much anymore.

Anyway, I can confirm again after few days, Audiofrog’s support and dedication to help are absolutely TOP of the line!


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## tjk_bail (Feb 2, 2012)

I purchased the Test Gear... 

I installed the mic per the instructions... 

Why is the microphone showing a HUGE peak beginning at about 55hz to about 70hz in REW? I tested the mic in a room that is completely silent, and the result on the graph in my REW looks very similar to the graph that on "Audiofrog-UMI-1-Setup-Instructions-for-REW.pdf".(page 25) 

In my REW graph, the the Dbfs shows a peak at about 15 in the 55 to 70hz range.... thats a huge huge peak for a completely silent room.... 

Do I need a different calibration file for the mic? or is there a reason for this peak embedded into the cal file ?


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