Room EQ

[AVT]

I'm trying to learn more about room EQ using something like miniDSP.

- How big of a difference does it make?
- Do people just do parametric EQ and that's it? Or is it fancier stuff - time alignment, etc? What is room EQ actually doing?
- Can techniques used for room EQ compensate for non-ideal speaker placement?
- Good $500 speakers vs good $100 speakers + room EQ. What do you prefer? Does this preference depend on whether or not the speakers are well-placed?

Thanks for any information!

 

[|Tch0rT|]

- How big of a difference does it make?
- Do people just do parametric EQ and that's it? Or is it fancier stuff - time alignment, etc? What is room EQ actually doing?
- Can techniques used for room EQ compensate for non-ideal speaker placement?
- Good $500 speakers vs good $100 speakers + room EQ. What do you prefer? Does this preference depend on whether or not the speakers are well-placed?

There are no simple answers for these...

Right now I just use PEQ's on my sub channel, later on I plan on using Dirac Room Correction on all 7.1 channels of my system. The newer way of thinking on EQ and PEQ is only good for frequencies under 250hz or so due to phase issues in higher frequencies.

1) For me it helps my subwoofers integrate/blend into my mains better. I reduce the peaks using PEQ's and it stops my subs from sounding boomy.

2) Some people just use basic PEQ to reduce peaks, which is what you'd use most miniDSP products for. I use time alignment but it's built into my AVR for systems without an AVR you can do it with software like JRiver or miniDSP's nanoAVR but that's more for multichannel setups, with stereo you can manually do it just by positioning. Then there's the more complicated Audyssey (and all their versions), Dirac Live, and Trinnov room correction software. Those can correct more than PEQ's can do, they do things in the time domain and other filters. I'm not keen on exactly how those work though but I know Dirac corrects the impulse response which you can't do with just PEQ's alone.

3) To a degree. Room correction and EQ is more of a band aid than a cure. It can help but it can't work miracles. Proper placement will go much further than room correction or EQ's as those are "last resort" or "final tweaks" kind of things IMO. Proper placement will always trump non proper placement with room correction and PEQ's.

4) This is something you'll never get a clear answer on. Personal taste alone makes this question unanswerable and then throw in that $500 speakers aren't necessarily better than $100 speakers + room EQ (not to mention that most PEQ or room correction costs more than the speakers at this point, hell Dirac is more expensive than $500) and on top of that the room itself will dictate the final sound. Good speakers in a shitty room or with improper placement usually will sound worse than cheaper speakers properly placed and in a decent room. This always kills me since I see crazy expensive speakers in rooms with nothing but hard reflective surfaces...

Anyway you'll probably get more responses and more technical detail if you ask this over at HomeTheaterShack or AVSforum.

 

[AVT]

There are no simple answers for these...

Right now I just use PEQ's on my sub channel, later on I plan on using Dirac Room Correction on all 7.1 channels of my system. The newer way of thinking is EQ and PEQ is only good for frequencies under 250hz or so due to phase issues in higher frequencies.

1) For me it helps my subwoofers integrate/blend into my mains better. I reduce the peaks using PEQ's and it stops my subs from sounding boomy and more natural.

2) Some people just use basic PEQ to reduce peaks, which is what you'd use most miniDSP products for. I use time alignment but it's built into my AVR for systems without an AVR you can do it with software like JRiver or miniDSP's nanoAVR but that's more for multichannel setups, with stereo you can manually do it just by positioning. Then there's the more complicated Audyssey (and all their versions), Dirac Live, and Trinnov room correction software. Those can correct more than PEQ's can do, they do things in the time domain and other filters. I'm not keen on exactly how those work though but I know Dirac corrects the impulse response which you can't do with just PEQ's alone.

3) To a degree. Room correction and EQ is more of a band aid than a cure. It can help but it can't work miracles. Proper placement will go much further than room correction or EQ's as those are "last resort" or "final tweaks" kind of things IMO. Proper placement will always trump non proper placement with room correction and PEQ's.

4) This is something you never get a clear answer on. Personal taste alone makes this question unanswerable and then throw in that $500 speakers aren't necessarily better than $100 speakers + room EQ (not to mention that most PEQ or room correction costs more than the speakers at this point, hell Dirac is more expensive than $500) and on top of that the room itself will dictate the final sound. Good speakers in a shitty room or with improper placement usually will sound worse than cheaper speakers properly placed and in a decent room. This always kills me since I see crazy expensive speakers in rooms with nothing but hard reflective surfaces...

Anyway you'll probably get more responses and more technical detail if you ask this over at HomeTheaterShack or AVSforum.

I see. I am mainly trying to decide whether adding miniDSP to my current setup will improve it at all. I use it to listen exclusively to music, so I am more concerned with clarity, etc, than other stuff like sound stage, stereo imaging, realistic explosions in movies, etc.

Placement in my case is not ideal and never will be as this is a 2.1 PC desktop setup, not a home theater setup. Speakers are placed on my desk, up against the wall, and the right speaker is between two monitors in a dual monitor setup, with about a 3" gap so the tweeter at least isn't totally obscured. I'd use a better placement, but there simply isn't anywhere else to put them.

Sub is placed directly underneath the speakers. I originally had it in a corner, but this made the bass sound directional (presumably due to the structure of the room), and moving it underneath fixed the issue.

In what frequency range are there usually problems that are correctable by room EQ? 100hz-1000hz? Under 100hz? If it is used primarily for subwoofer integration, then I definitely don't need it, as my sub sounds fantastic, absolutely dead flat down to 35hz, f3 somewhere below 30hz, and integrates well with my speakers.

What sort of problems do rooms / bad placement even cause in the first place? I know PEQ helped a lot in my car, so I am curious exactly what issues it might solve in the room given non-ideal placement.

 

[|Tch0rT|]

I see. I am mainly trying to decide whether adding miniDSP to my current setup will improve it at all. I use it to listen exclusively to music, so I am more concerned with clarity, etc, than other stuff like sound stage, stereo imaging, realistic explosions in movies, etc.

Placement in my case is not ideal and never will be as this is a 2.1 PC desktop setup, not a home theater setup. Speakers are placed on my desk, up against the wall, and the right speaker is between two monitors in a dual monitor setup, with about a 3" gap so the tweeter at least isn't totally obscured. I'd use a better placement, but there simply isn't anywhere else to put them.

Sub is placed directly underneath the speakers. I originally had it in a corner, but this made the bass sound directional (presumably due to the structure of the room), and moving it underneath fixed the issue.

In what frequency range are there usually problems that are correctable by room EQ? 100hz-1000hz? Under 100hz? If it is used primarily for subwoofer integration, then I definitely don't need it, as my sub sounds fantastic, absolutely dead flat down to 35hz, f3 somewhere below 30hz, and integrates well with my speakers.

What sort of problems do rooms / bad placement even cause in the first place? I know PEQ helped a lot in my car, so I am curious exactly what issues it might solve in the room given non-ideal placement.

You can use software to do what a miniDSP does to see if you want to spend the money on one. If you use DirectSound there's Equalizer APO (http://sourceforge.net/projects/equalizerapo/) for free. You can import PEQ filters generated by Room EQ Wizard. If you use WASAPI or ASIO you can try a 30 day trial of JRiver ($50) and it has a DSP with PEQ, time alignment, and other filters for audio and video files.

Room EQ's such as PEQ's are mainly just for under 250hz. You can use it up higher if you want but phase can change depending on position. Room correction like Audyssey, Dirac Live, and Trinnov can correct ~20hz - 20kHz. I'm not sure how they do it but it's more involved than just PEQ's, each brand has it's own mix. It might help for your situation but they're pricey (~$550+ for Dirac Live, Trinnov is 5 digits I think).

Regarding bad placement, sound bounces around the room depending on it and what's in it causes frequencies to get amplified (peaks) or out of phase (nulls). Proper placement balances the peaks and nulls.