# EQing and Pink Noise



## DanMan (Jul 18, 2008)

I have been slowly making progress tuning with the wealth of info available on this forum.Especially Cmusic's tutorial and MiniVanMan's.
One thing that I have been confused by is the notion of using Pink Noise to EQ with.I don't see mention of using any test equiptment(i.e. RTA) to do this.I have been baffled by this for months now,and its time I put pride aside and ask for ask for clarification.
Can someone please elaborate on how I would go about this?When I hear Pink Noise it sounds like static to me.What am I missing.Also,as far as separate left and right EQing,what is the goal?
Thanks for the help!


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## tcguy85 (Oct 29, 2007)

DanMan said:


> I have been slowly making progress tuning with the wealth of info available on this forum.Especially Cmusic's tutorial and MiniVanMan's.
> One thing that I have been confused by is the notion of using Pink Noise to EQ with.I don't see mention of using any test equiptment(i.e. RTA) to do this.I have been baffled by this for months now,and its time I put pride aside and ask for ask for clarification.
> Can someone please elaborate on how I would go about this?When I hear Pink Noise it sounds like static to me.What am I missing.Also,as far as separate left and right EQing,what is the goal?
> Thanks for the help!


all i know is thats it makes it real easy to hear any changes as you make them.

swap the phase of something and you'll hear the difference, mess with EQ or even T/A and you'll hear the difference.


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## CAMSHAFT (Apr 7, 2006)

Tuning with noise is retarded......unless you have a RTA...


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## tcguy85 (Oct 29, 2007)

CAMSHAFT said:


> Tuning with noise is retarded......unless you have a RTA...


sorta. i have heard of people tuning by ear with it though. not sure how well it works though.


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## SoCalSQ (Oct 7, 2008)

Use Pink Noise to get a start. After that tune by ear. DO NOT RELY ON IT !


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## SQ_Blaze (Sep 29, 2008)

tcguy85 said:


> sorta. i have heard of people tuning by ear with it though. not sure how well it works though.


Unless you have an RTA built into your noggin, you're not going to get anywhere by tuning by ear with pink noise.

And I guarantee if you listen to anyone's system where they "claim" they tuned by ear with pink noise, it's going to sound like open booty.

The only "cheap" way to tune would be to download test tones from 20Hz to 20kHz, and use a RatShack SPL meter to get them as close as possible to get you in the ball park. Even then, you would have to do a dry run on just measuring the untouched sound and use one of those downloadable sheets that shows how far off the RatShack SPL meters is at the frequency extremes, then calculate the differences from there so you have a rough idea on how much EQ to use.


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## mjgonegm (Jun 21, 2008)

SQ_Blaze said:


> Unless you have an RTA built into your noggin, you're not going to get anywhere by tuning by ear with pink noise.
> 
> And I guarantee if you listen to anyone's system where they "claim" they tuned by ear with pink noise, it's going to sound like open booty.
> 
> The only "cheap" way to tune would be to download test tones from 20Hz to 20kHz, and use a RatShack SPL meter to get them as close as possible to get you in the ball park. Even then, you would have to do a dry run on just measuring the untouched sound and use one of those downloadable sheets that shows how far off the RatShack SPL meters is at the frequency extremes, then calculate the differences from there so you have a rough idea on how much EQ to use.


Sry for bring this back to life but............

I know in my home system a combo of (Scott A1110) and My media center computer EQ.

I tune via the led power level indicator with test tones and match all freq.’s output from bass to the unbearable, and it works perfectly I get that sharp midbass that kicks you in the chest and having the high so it does not blow your ears out.

But with an spl meter how would you do this ?

I mean all the highs would be easy but the lows would be messed up because bass takes a different amount of power, highs are more easily tuned, IMHO 1-20 kHz uses the same amount of power to get about the same spl, but bass would need way more power to get the same spl.

what do you guys do ? Do you do it separate then just blend the bass to your taste ?


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## vecc205 (Nov 18, 2007)

If you have a really trained ear then you could possibly tune with pink noise. If you can optimize the speaker location, crossovers and time alignment you can get things to sound pretty good to start. I use an MLS program to give me a start but don't rely on it. Get a nice set of headphones or train you ear to be able to hear problem areas. The most important thing is to train your ears to be able to locate where the problems are whether they be in the lower midrange, midrange, the highs and familiarize yourself with the changes in those frequencies to see what part of the music they change. If you have to turn your music down because you ears feel uncomfortable you have some trouble spots to fix.


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## Q-Authority (Mar 31, 2008)

An RTA is really a must if wanting to use pink noise to fine tune the system. I've tried the 1/3 octave pink noise with Radio Shack meter approach (both in home and car) and it is not that reliable. There are too many factors it cannot account for (such as the way multiple frequencies interact with each other, etc.). The RTA vs. no RTA discussion goes way, way back, and almost everyone agrees that an RTA will produce far better results than those without one.


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## digitalhifi (Mar 26, 2009)

The idea of tuning with an SPL meter and test tones is actually kind of intriguing if you know how to produce precise sinusoidal tones:

First off make the tones: 
You should probably start with a center frequency (fc) at 20 Hz. You need to set your upper (fu) and lower (fL) frequency limits using the equations : fu = fc*srqt(2) and fL = fc/sqrt(2). (or if you're lazy use these fL an fu values Octave - DiracDelta Science & Engineering Encyclopedia You should generate a sine sweep like this for every third octave band up to 20kHz. You then need to play each tone individually and tune your system so the SPL meter reads the same desired level for each tone. You should probably have the meter set to slow and no weighting curve for this to actually work. You'll probably have to go back and re adjust a couple of times unless you have a standard 31 channel, 1/3 octave band eq. If anyone actually does this, I'd like to know how it works.

Or you can simply use an A weighted RTA and a pink noise signal and tune the system it until its flat. This will give a pretty good starting point for any fine tuning you may want to do.

Sorry, I rambled. Let me know if anyone wants me to post more about using an RTA to set a system. There's still some stuff I didn't mention.


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## smellygas (Feb 21, 2008)

Before there is any more misinformation spread here:
1) you CANNOT use pink noise and tune by ear; the reason is that at different overall volume levels, your notion of what equivalent loudness is of various frequencies will change. This phenonemon is described by the equal-loudness curves like Fletcher-Munson and others. Unless you are incredibly skilled, and happen to "ear tune" at the exact same A-weighted volume each time, your inaccuracy will be very high.
2) an SPL meter is designed to be accurate for broad-spectum noise across the designated weighting. They are not designed to have a flat frequency response from 20Hz-20kHz. In the case of the Rat Shack meter, it is WAY off above 1kHz or so, last time I looked at it.
3) even if you did have a perfectly flat SPL meter, sine waves are a poor test signal. What you really want is a smooth and balanced response at 1/3 octave resolution. However, within each 1/3 octave, there can be significant variation, and what you're doing is just taking a single point in the entire 1/3 octave, which you hope is representative. It's probably not.

What you want is the following:
a) calibrated microphone (the least expensive I've seen is ~$100 for a professionally calibrated ECM8000)
b) a pink noise source
c) an RTA with resolutions from 1/3 octave up to 1/24th or so
d) a sophisticated equalizer. a 1/3 octave equalizer is okay, but it's the bare minimum. a parametric eq with lots of bands is better. a DSP device that generates digital corrections is looking like the best option the more I think about it.
e) a target response curve that you will be equalizing towards (and it's NOT flat, by the way). if you get this far, you should see the thread 
http://www.diymobileaudio.com/forum...t-correlating-rta-plots-what-being-heard.html
f) if you're tuning with a 1/3 octave RTA, a 1/3 octave equalizer, and you're trying to get "flat," I GUARANTEE you will be disappointed and you will think RTA is worthless. 

Good luck.

SG


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## Ge0 (Jul 23, 2007)

DanMan said:


> I have been slowly making progress tuning with the wealth of info available on this forum.Especially Cmusic's tutorial and MiniVanMan's.
> One thing that I have been confused by is the notion of using Pink Noise to EQ with.I don't see mention of using any test equiptment(i.e. RTA) to do this.I have been baffled by this for months now,and its time I put pride aside and ask for ask for clarification.
> Can someone please elaborate on how I would go about this?When I hear Pink Noise it sounds like static to me.What am I missing.Also,as far as separate left and right EQing,what is the goal?
> Thanks for the help!


This is for the benefit of others reading this thread.

Pink noise in loose laymans terms means all frequencies played at once. The amplitude of these frequencies decreases as frequency increases. You can tune your system with it when used in conjuction with an audio range spectrum analyzer (RTA).

Your vehicle is a hostile environment for sound waves. Surfaces within the vehicle cause sound to reflect all over the place. In turn this causes cancellations and boosts at various frequencies.

Pink noise when used in conjuction with an RTA lets you see this all at once and take corrective actions assuming you have the electronics to do so. The net effect is combatting the cancelations and boosts caused by your vehicle to make your music sound as it was originally intended.

As far as left/right EQ...

Have you ever noticed the vocals or some other instrument/sound/effect wandering left or right from where you think it sould be? Or, does it sound diffuse or difficult to locate? Well, this is because the cancellations and boosts caused by your vehicles interior are not symetrical left to right. To fully gain a benefit from an EQ you need to at bare minimum be able to adjust frequency response independantly from the left or right side. Better yet, be able to measure and compensate for frequency response anomalies (cancelations and boosts) for each speaker independantly.

This does not come cheap though. You need to put the equipment in place to attain this goal. But, this is a whole topic onto itself and outside the bounds of this post.

Ge0


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## Crazedkiller (May 22, 2008)

I use a home stereo BSR EQ-3000 to produce and monitor pink noise over my car stereo though the aux input.I was sick of adjusting the eq for every different type of music I listened to.The result is flat enough for me.It may just be a placebo effect on me.


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## Q-Authority (Mar 31, 2008)

This is why we need more development of products like Alpine's Imprint (Audyssey). But for God's sake, stop the ridiculous factory stereo implementation advertisement for these things, or at the very least develop two separate lines and make one of them specifically for aftermarket hu's. These should be the biggest product development in years, if they handle it right. I've used the home version (Audyssey MultiEQ XT) since it was first introduced and I absolutely swear by it. The only downside is that even in the home, under very controlled scenarios, it still takes a lot of experimentation to make it work perfectly. But when it does, it is incredible. Using it in the car may always be more difficult, but who knows, maybe they'll develop some additional software that will magically accommodate the varying interior differences between vehicles, etc.


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## digitalhifi (Mar 26, 2009)

smellygas said:


> Before there is any more misinformation spread here:
> 1) you CANNOT use pink noise and tune by ear; the reason is that at different overall volume levels, your notion of what equivalent loudness is of various frequencies will change. This phenonemon is described by the equal-loudness curves like Fletcher-Munson and others. Unless you are incredibly skilled, and happen to "ear tune" at the exact same A-weighted volume each time, your inaccuracy will be very high.
> 2) an SPL meter is designed to be accurate for broad-spectum noise across the designated weighting. They are not designed to have a flat frequency response from 20Hz-20kHz. In the case of the Rat Shack meter, it is WAY off above 1kHz or so, last time I looked at it.
> 3) even if you did have a perfectly flat SPL meter, sine waves are a poor test signal. What you really want is a smooth and balanced response at 1/3 octave resolution. However, within each 1/3 octave, there can be significant variation, and what you're doing is just taking a single point in the entire 1/3 octave, which you hope is representative. It's probably not.
> ...


smellygas, that's a good point about the sine wave. I meant to say you have to filter broadband pink noise into 1/3 octave bands. My mistake. Theoretically, you can use an SPL meter to measure the loudness of each filtered signal one at a time. This is certainly not the most accurate method, and is highly dependent on the accuracy of your SPL meter. This is however how an RTA works, except it has the 1/3 octave filters inside of it.


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## Hillbilly SQ (Jan 26, 2007)

I've tuned by ear with frequency centered pinknoise with good results. Keeping amplitude the same all the way across the board makes a pleasing sound for me. My ears are also sensitive to minor changes in sound.


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## Ge0 (Jul 23, 2007)

How many of you have a laptop or some sort of computer you can haul out to your car?

How many of you have $80 or so to spend on a decent microphone? ****, I can direct you to a crude one for $30 shipped.

How many can scrounge up $60 or so on a good used USB microphone preamp?

I know you have access to the internet or you would not be posting here.

Aquire the necessary equipment mentioned above and then download a free RTA analysis software named ARTA. We'll teach you how to get good results (assuming you have the hardware necessary to make corrections), but, you need to do some legwork up front.

Ge0


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