[bpape]

Measuring each individually is the way to do it to look at impulse response and also to identify any issues specific to one side or the other due to asymmetry, differing reflection surfaces, etc. But in the end you also need to measure with both channels as that's how you listen.  If you have no problems with each individually but DO have a problem when both are going, it identifies an interaction between the 2 speakers that should be addressed.

[jlafrenz]

Have any of you guys used the Behringer UCA222 as a sound card for REW? It has both L/R RCA inputs and outputs.

[murphy11]

Measuring each individually is the way to do it to look at impulse response and also to identify any issues specific to one side or the other due to asymmetry, differing reflection surfaces, etc. But in the end you also need to measure with both channels as that's how you listen.  If you have no problems with each individually but DO have a problem when both are going, it identifies an interaction between the 2 speakers that should be addressed.

Brian, your advice about symmetry was really helpful! I was getting bummed about my left speaker measuring a lot different than my right. It never occurred to me that I was part of the symmetry equation during the measuring process - light bulb moment!  My left waterfall was a lot worse because I was kneeling on the left side of my laptop for both left and right measurements.

When I measured the left speaker from the right side of my laptop well away from left, the waterfall got significantly better. I was thinking that I would have to spend a lot of money on OC703 to fix the room but I'm going to try to live with it for now. Also, your suggestion of going more than 2" on reflection points helped as well. OMMV because I am using Armstrong ceiling tiles because of availability, but thanks again for the suggestions!

[murphy11]

More progress - bought some UltraTouch insulation to replace ceiling tiles as reflection point panel. Tweaked speaker placement and sofa placement - MUCH better compared to earlier measurements in my gallery. Still not done with trapping in corners and will toy with ceiling panel at some point. Hundreds of measurements and tests over the last month - more to come...

[Glenn Kuras]

View things in 1/24 or 1/48 smoothing.

Glenn
GIK Acoustics

[murphy11]

Glenn, doesn't look so impressive. I like 1/3 better   Center of huge dip is at 192.

[bladesmith]

What's going on at 200 hz ?

[murphy11]

No clue about 200. I've new to measuring and am not done with more testing. Also have not tweaked the amp settings on the minis so there could be more improvements possible.

[bladesmith]

No clue about 200. I've new to measuring and am not done with more testing. Also have not tweaked the amp settings on the minis so there could be more improvements possible.

You're on the right track,  grasshopper.

[TF1216]

Has anyone found a tutorial or an in depth approach to measuring one's speakers at the listening position?  Or how about a 3D tool like a BEM code for helping with visualizing the measurements to determine how to improve the room?

[Big Red Machine]

Have any of you guys used the Behringer UCA222 as a sound card for REW? It has both L/R RCA inputs and outputs.

There is a bunch of guidance on Home Theater Shack under the REW Forum:

http://www.hometheatershack.com/forums/rew-forum/

[TF1216]

There is a bunch of guidance on Home Theater Shack under the REW Forum:

http://www.hometheatershack.com/forums/rew-forum/

Thanks BRM!  I will check out the sticky threads and do some perusing the rest of the forum.

[Glenn Kuras]

Here is a video we make on REW.
http://www.gikacoustics.com/room-eq-wizard-tutorial/

[TF1216]

Here is a video we make on REW.
http://www.gikacoustics.com/room-eq-wizard-tutorial/

Thank you Glenn.  I just e-mailed you moments ago.  I am hoping to find a checklist of measurements to produce that will help you and your team suggest the best approach to improving the room.

[murphy11]

Pretty much done for awhile (hopefully) New measurements below 1/48 smoothing. Bass dips are filled in and smoother. The speaker amp settings were out of sync and syncing them improved bass significantly. The 200 dip must be a room mode which I am probably willing to live with. Turned off the amp and the dip is still there a little deeper and wider. Turning the amp on and the dip is from 181 to 212 but shallower.

Finished installing treatments and tried very hard at symmetrical placement of speakers, treatments and my couch. Interestingly, moving the couch back 6" made a fairly big difference in bass response.


 

[Big Red Machine]

http://www.bobgolds.com/Mode/RoomModes.htm

Type in your room dimensions here and see if it says the room is causing your 192 hz mode.

[murphy11]

The room is irregularly shaped kind of like a L but picture a block letter L.  Pics are in my gallery and it is a finished carpeted basement. The height is 81", the alcove where the speakers are is 91" wide and front wall to back wall is 234". I plugged those inches into bobgolds (BRM thx!) but I don't know how to interpret the output.

___________
       91        I
  S           S  I
                   I_________
                                    I
    COUCH            O        I
                          P         I
                          E        I
                          N        I
                                    I
                                    I
____________________I

[Hipper]

I've been through a similar measuring operation for the last nine months, using REW, a microphone, and a Behringer DEQ2496 Equaliser and have only recently settled on a satisfying solution.

I measured lots of speaker and ear positions and found two areas that offered the best measurements. One was based around 'The Thirds' set up (speakers and ears a third away from the relevant walls). The other had speakers and ears much nearer both walls. I settled on the latter.

At first I tried 'The Thirds' set up, measuring to refine the positioning, employing room treatment and finally tinkering the Behringer to get the flattest measurement throughout the full range of frequencies. However I found that a further refinement was needed by listening with my ears to pink noise test tones. Finally I listened to music, and based my judgement on comparisons with a good headphone sound. Only then did I get what I wanted.

The key points I learnt were:

Room treatment, especially bass traps, are essential.

Microphones do not represent your ears, particular as you get older and your hearing of upper frequencies deteriorates. Pink noise, and of course real music, are the best measurements.

When using REW, I used mostly the SPL graphs, with no smoothing up to 1 kHz, and 1/24 smoothing above 1kHz.

Do not put your equipment between the speakers. This is something I read in Jim Smith's book Get Better Sound and I found it makes a lot of difference. Reflections off the gear are reduced and you are free to place acoustic panels etc. on the front wall.

Most experts do not recommend using an equaliser full range but just to control bass frequencies up to say 400Hz. My experience is that I prefer full range treatment. In particular I adjust some of the higher frequencies to counter hearing loss (e.g. 6.3 kHz and 8 kHz have each a 4dB boost allowing me to hear some useful percussion otherwise lost).

So, if starting from scratch I would:

1. Buy (or make) and install room treatment based on expert advice and your room dimensions.

2. Using something like REW to locate the best position for your speakers and ears.

3. Improve the frequency response at your ears with REW and careful use of a digital equaliser.

4. Listen with your ears to pink noise test tones through the whole frequency range to refine the sound with the equaliser.

5. Listen to music and refine further if necessary.

It's a frustrating and time consuming business but eventually you should get a sound that satisfies you.

The alternative is to get someone like Jim Smith to 'voice' the system for you.

[Hipper]

Are you able to place your speakers along the long wall? That is, effectively turning your sofa 90 degrees anti clockwise?

You could leave the gear where it is, and toe in the speakers more so reducing side wall reflections. You would of course need longer speaker cables.

[murphy11]

My room is mostly used only be me so I have some flexibility in what I do with the space, but I can't change the orientation because my wife wants to leave space for the kids to play occasionally. The current placement works for me and also for the kids and wife.

My measurements are further improved by removing the equipment table behind the speakers by the front wall. Strange as it seems, opening and closing the doors in the room affect measurements. Doors open measure better than closed. During the day when it's only me I will listen with doors open.

The null at 199 is narrower and slightly shallower with no equip rack and with doors open. The measurements are better at 199, 425, 983, 1251 and 2K. Unsmoothed latest measurements have fewer narrow nulls that are not as deep. I need to do a better job of editing the same measurement and adding new measurements to the same file and keeping DB levels similar. Measuring on different days I can get lazy and not try to match; also mic placements can be slightly different. It would make comparing easier.