[asyvan]

So I was not happy with the sound (Harman Kardon, HK) in my X3 G01. I tried to play around with Bass/Treble/Equaliser but could not find the right setting. I decided to adjust the equaliser using Pink Noise and a RTA (Real Time Analyser). Pink Noise is sound on all frequencies, where the sound level drops 3dB every octave. With a RTA this should give a "flat" curve.

Using a high quality Pink Noise WAV-file and Octave RTA i looked at the result and tried to create as "flat" curve as possible (see picture). And to my surprise I had to adjust it quite a lot (see picture), and not at all as I would have guessed (and I did fail when trying before this).

As you can see on the pictures, the 100Hz needed some boost, the 200Hz needed to drop alot and 500Hz also needed some boost (100Hz and 500Hz boost is mostly to compensate for the drop in 200Hz, which affects a wide range of frequencies around 200Hz). I am not saying this setting is to everyone's liking, but according to my simple measure it gives as close to a flat curve as possible in my car. And it keeps a slight increase around 200Hz despite I lowered it.

Edit: forgot to mention, it sounds much better now.

[suby01]

Off topic here, but very interesting that it is being called a equaliser and not a equalizer like most other places.

[cjallstar]

Nice work! My first BMW without HK (got car off dealer lot this time for a great deal). I know the settings for the standard system aren’t nearly as customizable, but was wondering what the ideal settings are nonetheless

[asyvan]

Originally Posted by cjallstar

Nice work! My first BMW without HK (got car off dealer lot this time for a great deal). I know the settings for the standard system aren’t nearly as customizable, but was wondering what the ideal settings are nonetheless

Yeah well to be honest it was more of an experiment to see if it could be done. It could. And it did improve in my humble opinion.

[Oldguysrule]

Good info. The HK sysyem isn't a bad system. I suspect Bavsound has customized crossover points in addition to EQ settings for their amp. A doubling of amplifier power gives you +3db of additional sound output so the overall volumes you can drive with a 600w vs 1200w amp aren't drastic.

I am an audio collector of sorts and have 3 different 2-channel systems set up in my home and numerous individual pieces of equipment I move around within those systems. The HK system sounds pretty good to me using a good material source. I don't listen at really loud levels in the car though as I prefer to focus on driving these days. Too many idiots on the roads.

[titomi]

This might be of interest - HK System EQ Settings > https://x3.xbimmers.com/forums/showthread.php?t=1572720

[satz]

Interesting... I wonder how different it would be if you could do it while driving...to take into account road/engine/tyre noise?

Bit dangerous to measure of course!

I run my equaliser flat except for the lowest two frequencies, which I've boosted slightly to compensate for the road noise.

[Oldguysrule]

Originally Posted by titomi

This might be of interest - HK System EQ Settings > https://x3.xbimmers.com/forums/showthread.php?t=1572720

" I can comfortably listen at my "normal listening volume" - which is about 70% to 75%." That's pretty loud. Don't know how you'd even hear an emergency vehicle if they were right behind you. I have a sound pressure level meter and I'll give it a go at that volume. Hearing damage imminent I suspect.

[titomi]

Originally Posted by Oldguysrule

" I can comfortably listen at my "normal listening volume" - which is about 70% to 75%." That's pretty loud. Don't know how you'd even hear an emergency vehicle if they were right behind you. I have a sound pressure level meter and I'll give it a go at that volume. Hearing damage imminent I suspect.

Yes, that's also very loud to me. I didn't start that thread.

[Oldguysrule]

Originally Posted by titomi

Yes, that's also very loud to me. I didn't start that thread.

Yes, I know.

[gugin]

What microphone did you use for the RTA? Was it the built-in microphone in the iPhone or did you use an external omnidirectional mic? If the former, what happens when you change the angle of the iPhone relative to ground or move it to a different spot in the car? Do you get different readings?

[asyvan]

Originally Posted by gugin

What microphone did you use for the RTA? Was it the built-in microphone in the iPhone or did you use an external omnidirectional mic? If the former, what happens when you change the angle of the iPhone relative to ground or move it to a different spot in the car? Do you get different readings?

I used the iPhone mic. Held it with mic forward towards windscreen at the position of the drivers right ear.
But it didn't give me any different result if I held it in another direction.
The mic in a phone can't be particularly good, but it was more of an experiment. And it did find the 200Hz problem so I could adjust to remove it.

[asyvan]

Did some more tests with the "Octave RTA" iPhone iOS app.
http://onyx3.com/SpectrumAnalyzer/RTA/

Used again the high quality Pink Noise file on a USB stick.
https://www.audiocheck.net/testtones...itionaudio.php

As you can see below, I think I succeeded in getting a really flat curve compared to the curve when Equaliser was not adjusted. But the changes at 200Hz are still dramatic.
In the final end though, it's your taste and your ears that decide on what settings you will use.

Good luck.

[Alias1431]

What was your thought process behind not raising the last treble bar to try and raise 16k+?

[asyvan]

Originally Posted by Alias1431

What was your thought process behind not raising the last treble bar to try and raise 16k+?

That my microphone in the iPhone is not capable of reading those frequencies with any sort of accuracy. I don't know if that is the case, but that was my assumption and thus I didn't even try adjusting the highest frequency.

[corn18]

Originally Posted by asyvan

Did some more tests with the "Octave RTA" iPhone iOS app.
http://onyx3.com/SpectrumAnalyzer/RTA/

Used again the high quality Pink Noise file on a USB stick.
https://www.audiocheck.net/testtones...itionaudio.php

As you can see below, I think I succeeded in getting a really flat curve compared to the curve when Equaliser was not adjusted. But the changes at 200Hz are still dramatic.
In the final end though, it's your taste and your ears that decide on what settings you will use.

Good luck.

Thanks for doing this work. I used to be a sound engineer for smaller bands and used an omnidirectional mic that had a measured and known response curve. Then I would run pink noise into the RTA and then out the speakers and the RTA software would do some magic and spit out frequency maps showing where the speaker output differed from the RTA input. I could do this real time with any sound (live music) but always did it once initially with pink noise to establish my flat baseline. Then I would tune it to the room before sound check. I wouldn't muck with it during the gig as I would be busy tackling any feedback in the monitors and trying to get a good sound in the audience when the lead guitarist insists on cranking his amp to 11 on stage.

The reason I am saying all of this is that a system tuned to flat sounds a million times better than any other tuning I have tried. Flat means the sound coming out is identical to the sound going in. That is a magical thing.

So I am going to download your apps and files and do this to my wife's X3. I think I got it close by ear but would prefer data to establish a baseline.

[asyvan]

Originally Posted by corn18

Thanks for doing this work. I used to be a sound engineer for smaller bands and used an omnidirectional mic that had a measured and known response curve. Then I would run pink noise into the RTA and then out the speakers and the RTA software would do some magic and spit out frequency maps showing where the speaker output differed from the RTA input. I could do this real time with any sound (live music) but always did it once initially with pink noise to establish my flat baseline. Then I would tune it to the room before sound check. I wouldn't muck with it during the gig as I would be busy tackling any feedback in the monitors and trying to get a good sound in the audience when the lead guitarist insists on cranking his amp to 11 on stage.

The reason I am saying all of this is that a system tuned to flat sounds a million times better than any other tuning I have tried. Flat means the sound coming out is identical to the sound going in. That is a magical thing.

So I am going to download your apps and files and do this to my wife's X3. I think I got it close by ear but would prefer data to establish a baseline.

Thanks for your input. I actually don't know anything about this, just wanted to experiment.
I would be very interested in your result and conclusions, please update when you have something.
👍👍👍

[satz]

While this is great work, is it just me that thinks we should try to determine the equalisation at frequencies, while the car is moving (perhaps at 100kmh)? Then we could try to account for 'steady' background noise like tyre roar?

[corn18]

Originally Posted by satz

While this is great work, is it just me that thinks we should try to determine the equalisation at frequencies, while the car is moving (perhaps at 100kmh)? Then we could try to account for 'steady' background noise like tyre roar?

The method in this thread won't work well for this. You would end up cutting the frees that the car is putting out from the pink noise and then your music would not be flat, but the spectrum would be. That would sound like poo.

You would need something like SMAART to do what you are thinking of. Smaart compares a reference signal (input to stereo) to what is coming out of the stereo. You would have flat music playing on top of the car noise. At that point, you could take that system down the road and use it to flatten the response in a moving car. That would be interesting to try.

[PostModernHero]

Originally Posted by corn18

I wouldn't muck with it during the gig as I would be busy tackling any feedback in the monitors and trying to get a good sound in the audience when the lead guitarist insists on cranking his amp to 11 on stage.

HA!

[strohw]

Generally speaking you don't want to tune for flat. I say generally because most people don't like a flat frequency response but sound is subjective.

What you want is a gradual roll off as you move towards the top end of the frequency range. It's how most people will prefer their sound in cars and home audio. It's especially more common in cars as all the hard materials tend to cause issues in the high frequency range while the road noise causes issues in the low frequency range.

A good starting point is something like 0db at 50hz rolling off to -6db at 15khz.

[asyvan]

Originally Posted by strohw

Generally speaking you don't want to tune for flat. I say generally because most people don't like a flat frequency response but sound is subjective.

What you want is a gradual roll off as you move towards the top end of the frequency range. It's how most people will prefer their sound in cars and home audio. It's especially more common in cars as all the hard materials tend to cause issues in the high frequency range while the road noise causes issues in the low frequency range.

A good starting point is something like 0db at 50hz rolling off to -6db at 15khz.

Well that is the thing with pink noise. It falls -3dB every octave. White noise is same energy on all frequencies.
So tuning for a flat curve using pink noise actually means you allow for higher energy in lower frequencies and it drops off -3dB every octave.