View Single Post
      11-28-2016, 05:53 PM   #1

Drives: 2014 335i XDrive MSport
Join Date: Jun 2016
Location: Wisconsin

iTrader: (0)

F30 335i HK System mic'd, measured and EQ'd

Ever since I bought my 2014 335i over a year ago I've always wanted to take one of my Smaart rigs out to take some measurements/tune my car. Well I've been on tour now stop in this last year and never really had the time. Today I got bored and I decided to go out to my car take some quick measurements and see what's really going on...

Equipment used:

Lenovo x230t running windows 7
Smaart 8
Smaart iO
Isemcon EMX-7150 mic with calibration file

Car volume at half.

Mic was put in a clip and attached to the headrest approximately wear my head would be. Pink noise was generated from Smaart to use as a reference, split and fed into the car's stereo via the aux 3.5mm input.

Here is a trace with the EQ flat and L7 on. If you ever wondered why it sounded phasey, thin and odd... It's because it's exactly that. It's a great example of what happens and the challenges faced when adding more speakers into the mix.

Here is a trace with L7 turned off and the EQ still flat. I had it overlap the L7 trace so you can compare the difference. As you can see phase is improved and so is frequency response as a result. No, I'm not digging any deeper here as to what exactly L7 is doing, so deal with it. Frankly, I just don't have that kind of control over the factory system. The green line is L7 off and pink is L7 on.

Now here is the trace of the system with the limited EQ that is available on the F30 335i SEDAN HK system. Keep in mind, this is about the response I am going for with subwoofers in a large format concert PA system. The low mid 100-250hz region is really content and mix dependent. I will probably mess with the 200hz a bit as I listen to it more. That being said, I will probably adjust the "bass" a bit as well.

To achieve all of this my settings were as follows: (Newest settings at bottom of post)

Bass +5
Treble +2

100hz +3
200hz -3
500hz -4
1khz +4
2khz -4
5khz +3
10khz -2

I listened to a variety of music from CD after to verify. The CD's ranged from:

Jennifer Warnes - "The Hunter"
Norah Jones - "Come Away With Me"
Gojira - "l'Enfant Sauvage"
Modest Mouse - "We Were Dead Before The Ship Even Sank"

I found myself adjusting the bass for each, but will finally settle on something I'm sure.


Went back out to the car today and took some better measurements and have a few more things to share. I ended up listening to about 20 more CD's as well and think I've settled on some settings. I'm sure I will end up constantly adjusting things though... All measurements and EQ'ing done today were with the car's volume 1/2 way up (THIS IS IPORTANT). I generally listen to my stereo at 1/2 so that's why I chose this volume. I also discovered there is about 34ms of delay in the stereo from input to microphone. I don't know whats going on under the hood but that is a ton.

Here we have a new trace of the EQ flat and L7 on.

Here is the new trace with EQ flat and L7 off. As you can see, the phase response is greatly improved.

Now the two overlaying one another. L7 on being red and L7 off being blue.

Here are is the new tune with the old. New being blue and old being red.

Now with some smoothing applied. New is blue and old is red.


Have you ever wondered why the stereo seems like it sounds completely different at different volumes? It's because it actually does. These next measurements were taken at 1/4, 1/2 and 3/4 volume. The phase shift from the different volumes/EQ is pretty normal.

Apparently BMW does use their own sort of loudness curve for the different volumes. This feature drives me a little crazy. I find myself constantly grabbing the bass knob and turning it down at lower listening levels. Personally I think it still does a pretty poor job... Thank you to Integral Audio for clarifying this!

The orange is 1/4 and blue is 1/2.

Now here is 1/2 compared to 3/4. 1/2 is blue and 3/4 green.

All three.

All three with some smoothing.


Because Integra Audio brought some very good points to the table I felt like going back out to the car for more measurements...

Due to the simplistic nature of what I am doing, the lack of any sort of jig to hold mics (for consistency) and being limited to only a quad matched set of microphones, everything done below are single microphone measurements for demonstration. If I were to actually be designing a system for the vehicle, I do not believe I could get away with anything less than 4-8 microphones. I would essentially position them 2-4 per a side of the headrest, simulation where the ears would be located and at different heights for different listening levels for people of varying heights. Where you actually place this as far as distance from the steering wheel is a whole other decision. I feel as though with a set up as such you would be able to make more educated decisions as to phase, timing, delay, EQ, etc. Making these decisions inside of a vehicle is nothing but give and take and compromise. I do not envy anyone who wants to design car audio systems for a living. For everything I did above, I centered the microphone about where the center of my head would be to give me some sort of balance between what is happening on the left side of my head to the right. If I had any more control of or had anything other than the simple EQ available to me in the car, I would done multiple measurements and averaging to start. For my purposes, I did not deem it necessary.

Here we have 6 measurements of the HK system FLAT with no EQ and L7 OFF. 3 of which were done at the bottom of my headrest, left, center and right, and 3 were done at the top of my headrest, left, center and right. All of these measurements were done only a few inches from one another, but look at how different they vary!!! Time was reset for each measurement, of course, and smoothing is at 1/12 Octave.

Below is an average of the result of the above with 1/3 octave smoothing.

Here is an overlap of the initial measurement in blue and our new average in yellow. As you can see they are very similar, but definitely do differ! This is exactly why Integra Audio is 100% correct in saying that a measurement that is corrected in one particular area, will be very wrong in another. 1/3 octave smoothing has been applied here.

A comparison between the initial in blue and the new in yellow with octave smoothing applied.

Here we have the same 6 measurements, but with the tune I applied to the system. 1/12 octave smoothing here.

Now here is the tuned average with 1/3 octave smoothing.

A comparison of the initial tune measurement in blue and the new average in green. Again, looking similar, but they definitely differ! 1/3 octave smoothing here.

Here are the same to compare, but with octave smoothing applied.

Here is a comparison of the two new averages we just did. The factory HK system FLAT with no EQ is yellow and the new tuned version is green. 1/3 octave smoothing.

Here are the same two with octave smoothing.

Just for fun, here is a comparison of a target curve for an engineer I work with regularly in the concert world. Now his curve is just that of a 3 system with low, mids and highs, but no subwoofers. Very similar and it is no accident that my ears wanted to hear same 18dB difference between 60hz and 1khz here. Also of mention you'll notice his curve has quite a bit less, 200-500hz in it. This target curve is dedicated for arenas and in such a reverberant space, a lot of that body that is missing comes from the room. Quite different from what's happening inside of our cars. Dealing with ~80 open microphones on stage presents another set of challenges as well.


Now some of you may ask, "what about with L7 on?". Here you go!

L7 on with no EQ is purple while the EQ I applied is green. There's a touch more low end in it than I wanted, but with the car'a factory EQ, I compromised.

Smoothed out.

Here are both of my tunes on top of one another. L7 ON is green while L7 OFF is yellow.

Smoothed out.

That's all for now. Thanks for taking a look!

My newest Logic 7 OFF EQ settings are:

Bass +2
Treble +1

100hz +4
200hz -2
500hz -4
1khz +5
2khz -5
5khz +3
10khz -1

My newest Logic 7 ON EQ settings are:

Bass flat
Treble +1

100 +7
200 -6
500 -4
1k +5
2k -4
5k +2
10k -1

The fun part about this is, sound is VERY subjective. Just because one person finds one setting pleasing, the very setting can be overwhelming for another. In no way shape or form am I saying this is the end all be all. Have fun with it and mess around. See what works best for you!

Comments are welcome. Thanks.

Last edited by HKD126; 12-02-2016 at 03:00 PM..