Pink noise calibration - post your curves !

RobWells · 12th December 2005, 10:26 PM

I've been using pink noise and trueRTA to set up my systems for a few years, and have always been unhappy with a flat response. Reading up on this kind of thing suggests that the harsh mid / treble I get is due to the bass freq's reflections being added to the direct sound, causing me to up the (more direct) treble to match the bass.. ie: the bass is measured with reflections, the treble is direct leading to a boost in higher freq's.

Some books suggest target curves, such as the 'Handbook for sound Engineers', but I'm assuming this is for larger spaces than mine. (have tried the suggested curves)

At the moment I'm using a 1dB / oct drop from 20Hz to 20kHz. This gives a pretty good balance, but still harsh with films at reference levels.

I'm using right now:

mono subs:

2 sealed tempests 10Hz - 30Hz crossed 24dB/oct to:
2 Labhorns 30 - 80 crossed 24dB/oct to

stereo mains (per side)

1 beyma lx60 15" (sealed) 80 - 330Hz crossed 24dB/oct to
1 Precision devices PD107 10" (sealed) 330 - 1200Hz crossed 24dB/oct to
1 Beyma 380 1" cd on a TD250 (90 x 40) horn 1200 - 20k

What I thought would be cool is if people could post a response at listening position with a few words about what their system comprises of and what they feel it sounds like with music / dvd's etc. I'm gonna do a plot tomorrow, as it's past my bedtime right now

I think this could be quite a useful 'real world' thread if enough people post..

Cheers!

Rob.

imix500 · 12th December 2005, 11:01 PM

Considered using a fft program live Smaart Live? Or a SIM 3 if you've got 10 large laying around.

Ron E · 12th December 2005, 11:18 PM

Systems which sound harsh in the treble when equalized flat usually have power response that drops with frequency (the norm for speakers) or when the environment they are in is very absorptive at high frequencies.

Equalize your speakers so they are flat anechoically (outside) and then work from there. Usually you will want to bring down the 3-4k range a dB or so... Small changes are better than large ones at the fine tuning stage. Move a slider a small amount and listen to a few songs, etc...

If you can't bring them outside: Before I had measurement gear I used to have decent luck making it flat in-room or in-car with band limited noise up to 1-2Khz and then make minor adjustments by ear above that.

claudio · 13th December 2005, 12:04 AM

Hi,
in 1974 Moller showed the ideal 1/3 octave pink noise curve, for audio listening: obtaining such a curve means you have a well sounding system, no matter the music genre. I don't hear many people talking about Moller's response, unfortunately. Be aware that you need 2 pink noise generator, to compare your system with Moller's curve.
Henning Møller, “Hi-Fi Tests-with 1/3 Octave Pink Weighted Random Noise”, AES convention 47 (February 1974), Preprint Number A-5.

Regards,
Claudio

ralphs99 · 13th December 2005, 11:52 AM

Hi Rob,

What Ron said...

Smith, Keele & Eargle in their paper 'Improvements in monitor loudspeaker design' were the first that I know of to explore the realtionship between house curves and the power response of speakers. It's well worth reading.

Cheers, Ralph.

catapult · 13th December 2005, 07:29 PM

It's not just the power response of the speaker but the absorptive characteristics of the room. Most rooms absorb the highs more than the lows. So, even a speaker with flat on-axis anechoic response and perfect power response will still show rolled-off in-room highs with pink noise and an RTA. EQ'ing that speaker flat with an RTA will make it sound too bright.

imix500 · 14th December 2005, 01:43 AM

That's why Source Independent Measurement is so great.

hobby1 · 14th December 2005, 08:22 AM

hi rob

catapult say it all...

i had the same problem whit in room measurement,the solution i use now is measuring driver by driver in very nearfield whit the "rel" fonction in truerta before each measurement.

i place the mic at about 10 cm ,apply "relative" to get a "reference" ,make measurement and save it
apply the same method for the other driver,and adjust level of driver to get the same spl for each,but very important use "rel" before each measurement.

at listening position it don't give a flat response but very clean sounding

excuse my poor english....
greets

RobWells · 14th December 2005, 10:57 PM

Thanks for the responses, though most just confirm what I said in the initial post:

ie: the bass is measured with reflections, the treble is direct leading to a boost in higher freq's.

I was hoping to get some in room measurements that could prove useful for me and many others..

Looks like I'll tread the journey alone

Will post curves as I get time to do so...

Rob.

Coolin · 15th December 2005, 10:41 AM

Hi Rob,

How well is everything time aligned?

Just yesterday i noticed again how fat or thin the low end can sound by adjusting the delay.

CO

12th December 2005, 10:26 PM	#1
RobWells diyAudio Member Join Date: Aug 2002 Location: UK	Pink noise calibration - post your curves ! I've been using pink noise and trueRTA to set up my systems for a few years, and have always been unhappy with a flat response. Reading up on this kind of thing suggests that the harsh mid / treble I get is due to the bass freq's reflections being added to the direct sound, causing me to up the (more direct) treble to match the bass.. ie: the bass is measured with reflections, the treble is direct leading to a boost in higher freq's. Some books suggest target curves, such as the 'Handbook for sound Engineers', but I'm assuming this is for larger spaces than mine. (have tried the suggested curves) At the moment I'm using a 1dB / oct drop from 20Hz to 20kHz. This gives a pretty good balance, but still harsh with films at reference levels. I'm using right now: mono subs: 2 sealed tempests 10Hz - 30Hz crossed 24dB/oct to: 2 Labhorns 30 - 80 crossed 24dB/oct to stereo mains (per side) 1 beyma lx60 15" (sealed) 80 - 330Hz crossed 24dB/oct to 1 Precision devices PD107 10" (sealed) 330 - 1200Hz crossed 24dB/oct to 1 Beyma 380 1" cd on a TD250 (90 x 40) horn 1200 - 20k What I thought would be cool is if people could post a response at listening position with a few words about what their system comprises of and what they feel it sounds like with music / dvd's etc. I'm gonna do a plot tomorrow, as it's past my bedtime right now I think this could be quite a useful 'real world' thread if enough people post.. Cheers! Rob.

12th December 2005, 11:18 PM	#3
Ron E diyAudio Member Join Date: Jun 2002 Location: USA, MN	Systems which sound harsh in the treble when equalized flat usually have power response that drops with frequency (the norm for speakers) or when the environment they are in is very absorptive at high frequencies. Equalize your speakers so they are flat anechoically (outside) and then work from there. Usually you will want to bring down the 3-4k range a dB or so... Small changes are better than large ones at the fine tuning stage. Move a slider a small amount and listen to a few songs, etc... If you can't bring them outside: Before I had measurement gear I used to have decent luck making it flat in-room or in-car with band limited noise up to 1-2Khz and then make minor adjustments by ear above that. __________________ Our species needs, and deserves, a citizenry with minds wide awake and a basic understanding of how the world works. --Carl Sagan Science is a way of thinking much more than it is a body of knowledge. --Carl Sagan

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12th December 2005, 11:01 PM	#2
imix500 Proud Union Member diyAudio Member Join Date: Mar 2004 Location: Nashville, TN	Considered using a fft program live Smaart Live? Or a SIM 3 if you've got 10 large laying around.

13th December 2005, 12:04 AM	#4
claudio diyAudio Member Join Date: Feb 2002 Location: Italy	Hi, in 1974 Moller showed the ideal 1/3 octave pink noise curve, for audio listening: obtaining such a curve means you have a well sounding system, no matter the music genre. I don't hear many people talking about Moller's response, unfortunately. Be aware that you need 2 pink noise generator, to compare your system with Moller's curve. Henning Møller, “Hi-Fi Tests-with 1/3 Octave Pink Weighted Random Noise”, AES convention 47 (February 1974), Preprint Number A-5. Regards, Claudio

13th December 2005, 11:52 AM	#5
ralphs99 diyAudio Member Join Date: Jul 2006	Hi Rob, What Ron said... Smith, Keele & Eargle in their paper 'Improvements in monitor loudspeaker design' were the first that I know of to explore the realtionship between house curves and the power response of speakers. It's well worth reading. Cheers, Ralph.

13th December 2005, 07:29 PM	#6
catapult diyAudio Member Join Date: Dec 2002 Location: Planet Earth	It's not just the power response of the speaker but the absorptive characteristics of the room. Most rooms absorb the highs more than the lows. So, even a speaker with flat on-axis anechoic response and perfect power response will still show rolled-off in-room highs with pink noise and an RTA. EQ'ing that speaker flat with an RTA will make it sound too bright.

14th December 2005, 01:43 AM	#7
imix500 Proud Union Member diyAudio Member Join Date: Mar 2004 Location: Nashville, TN	That's why Source Independent Measurement is so great.

14th December 2005, 08:22 AM	#8
hobby1 diyAudio Member Join Date: Jun 2004 Location: paris	hi rob catapult say it all... i had the same problem whit in room measurement,the solution i use now is measuring driver by driver in very nearfield whit the "rel" fonction in truerta before each measurement. i place the mic at about 10 cm ,apply "relative" to get a "reference" ,make measurement and save it apply the same method for the other driver,and adjust level of driver to get the same spl for each,but very important use "rel" before each measurement. at listening position it don't give a flat response but very clean sounding excuse my poor english.... greets

14th December 2005, 10:57 PM	#9
RobWells diyAudio Member Join Date: Aug 2002 Location: UK	Thanks for the responses, though most just confirm what I said in the initial post: ie: the bass is measured with reflections, the treble is direct leading to a boost in higher freq's. I was hoping to get some in room measurements that could prove useful for me and many others.. Looks like I'll tread the journey alone Will post curves as I get time to do so... Rob.

15th December 2005, 10:41 AM	#10
Coolin diyAudio Member Join Date: Apr 2003 Location: Holland	Hi Rob, How well is everything time aligned? Just yesterday i noticed again how fat or thin the low end can sound by adjusting the delay. CO

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