EQ for my room, speakers and ears

[Hari Iyer]

Last week i purchased a dbx 31+ 31 band graphic EQ for an excellent price from Amazon. The purchase was more impulsive as i had not planned how to use them. I researched a lot about house curves and narrowed on two of them the Harman house X curve and the B&K house curve.

Some background about my listening room -

Length - 16 feet, Breadth - 9.75 feet, Height - 8.5 feet

Speakers are 72" away from front wall and 24" away from left and right side wall. Sweet listening spot is also 72" way centered between left and right speakers. There is around 66" space from the sweet spot to the rare window.

I measured with the microphone on the sweet spot with no EQ and this is what i get for both L+R speakers



This is the B&K target house curve. To achieve this we need to feed pink noise and measure with 1/3rd octave averaging RTA spectrum. The B&K curve has a flat response till 200Hz and from 200Hz till 2KHz there is a -3dB tilt and again from 2KHz till 20KHz another -3dB tilt. I EQed with my 31 band equalizer to achieve this.



This is my target B&K curve for my speakers + room after EQ




This is how the MLSA sine sweep measure after the EQ




I have to fully comprehend how they sound to my ears as i got busy with other stuff, may be by this weekend i shall be in a better position to fine tune them to my ears.

Thanks for looking,

 

[Hari Iyer]

One more reason i did not go the DSP mode was i did not want a A-D-A route in my signal path. The dbx is a fully analogue device, fully manual controlled. But unless you can measure and EQ the B&K curve it will be difficult to tune only with ears - though it should be possible. The challenge is to get even response in all areas of your room which i think should be the final goal. I was surprised how EQing allowed even gain at the low-end without much affecting the rest of the spectrum. I have to reduce the overall final gain to around -6dB levels for listening at night due to conservative neighbors, while playing at 0dB levels allow a much open sound stage. I also noticed that with this EQ listening to mp3 is horrible but CD recordings sound fantastic.

 

[elangoas]

The B&K curve has a flat response till 200Hz and from 200Hz till 2KHz there is a -3dB tilt and again from 2KHz till 20KHz another -3dB tilt.

Am guessing that near flat response until 200Hz is probably is due to "equal loudness" phenomen..

This is how the MLSA sine sweep measure after the EQ

There seems a big dip at 60Hz in midst of peaks.. Also, at 40Hz before EQ, the SPL is at 80 dB SPL.. After EQ 40Hz has come up to 95 dB SPL..

Speakers are 72" away from front wall and 24" away from left and right side wall. Sweet listening spot is also 72" way centered between left and right speakers. There is around 66" space from the sweet spot to the rare window.

Is this your dedicated room for stereo?.. You seem to have lot of space to pull the speakers in to the room just to get the sweetspot.. You being a DIY'er, haven't you considered subs for your room?.. With only 2 subs, there is every possibility that you can get the response fairly good <=80Hz just by positioning..

Length - 16 feet, Breadth - 9.75 feet, Height - 8.5 feet

Also have you tried swapping your room dimensions, so that your L/R are spread along the room width, which can reduce some important resonance below 80hz?..

 

[Hari Iyer]

Am guessing that near flat response until 200Hz is probably is due to "equal loudness" phenomen..

Don't know if that is because of FM curve of personal taste of the subjects in the B&K test.

There seems a big dip at 60Hz in midst of peaks.. Also, at 40Hz before EQ, the SPL is at 80 dB SPL.. After EQ 40Hz has come up to 95 dB SPL..

That's my normal room mode + comb filtering. That can't be EQed, only room treatment can address that. I have to live with that. Cant make out during listening.

Is this your dedicated room for stereo?.. You seem to have lot of space to pull the speakers in to the room just to get the sweetspot.. You being a DIY'er, haven't you considered subs for your room?.. With only 2 subs, there is every possibility that you can get the response fairly good <=80Hz just by positioning..

This is my living room where even the LED monitor is kept and shared with other members of family. This response is for OB + H-frame sub (single). Using 2 subs in my small room could overload the room. Even with a single sub - i prefer using the -6dB shelving filter on the dbx below 50Hz to reduce the +6dB room gain for the sub.

Also have you tried swapping your room dimensions, so that your L/R are spread along the room width, which can reduce some important resonance below 80hz?..

Had done that before with my earlier speaker, the seating arrangements don't allow me this placement.

 

[elangoas]

Don't know if that is because of FM curve of personal taste of the subjects in the B&K test.

From what i have read, human hearing needs a boost in SPL, especially lower freq to perceive it at the same level as higher freq SPL..

That's my normal room mode + comb filtering. That can't be EQed, only room treatment can address that. I have to live with that. Cant make out during listening.

Ok.. But you would be aware that treatments for low freq and he thickness needed could be challenging..

This is my living room where even the LED monitor is kept and shared with other members of family. This response is for OB + H-frame sub (single). Using 2 subs in my small room could overload the room. Even with a single sub - i prefer using the -6dB shelving filter on the dbx below 50Hz to reduce the +6dB room gain for the sub.

My living room is smaller then yours, 14 (W) x 11 (L) and i have 4 sealed subs in the room.. Never felt it was overpowering, in fact it is more satisfying..

I understand, bass preferences can vary from person to person and the limitations of placement in a living room.. May be one more identical sub should help you tame some peaks & improve that null before EQ?..

Had done that before with my earlier speaker, the seating arrangements don't allow me this placement.

Hmm.. That would have been nice option to eliminate some problematic low freq..

 

[Hari Iyer]

As per the B&K study the room adds around 1dB/octave in the range from 20Hz to 20KHz. So speakers having a flat anechoic response when placed in a normal sized listening room will have a +6dB upward till from 200Hz onwards till 20KHz. Such a speaker will sound a bit bright in normal listening rooms. The B&K house curve will till the response 1dB/octave so at listening position the room is equalized. There are no hard rules as to how much equalization will be required for each room, but most rooms benefit with a downward tilt. Heavily treated rooms with plenty of bass traps, first/ second reflection consideration etc may not require such aggressive cut at HF, but only final listening can confirm.

 

[ISO]

Flat speaker response is good for the measuring microphone but not for human ear.
Human ear loudness is more for the mid range than low and high frequency. So flat speaker response will be louder (in the mid range) to the human ear. IMO 'V' shape response curve of the speaker is more sweet to the human ear.

Many pro headphone has V shape curve for the same reason?

 

[alpha1]

Many pro headphone has V shape curve for the same reason?

I think real PRO headphones will be transparent with as flat as possible response.
It is the pseudo "PRO" equipment that will deliberately dip the mids.

 

[Hari Iyer]

The Harman house Xcurve has studied the in head response of the ear for head phones. Based on the structure of the ears the ear receives +10dB boost in response at 3kHz and the response gradual rise from 100 Hz to 3 kHz with +10dB boast. From 3 KHz till 20KHz there was a -10dB gradual linear cut. So a flat sounding headphone would sound bright in the midrange unless equalised. Most high end headphones try to achieve the Harman inear target response for pleasant listening experience