Crossover, speaker alignment, room equalization - what do I start with?

Hello wonderful community,

So I have 2.1 system and basically nothing set up, no crossover, no room correction, nothing and I don't know what should be the first thing to fix or do: speaker alignment, or crossover, or first equalize mains and sub separately...what is your first step in REW after connecting and positioning all the speakers? I will first try to fix mains and go from there, but I think maybe speaker alignment should be a first step since I have subwoofer very far away from me.

Thanks

Welcome to the Forum!

I know this stuff can be intimidating. First, set up the crossover between the mains and sub, time-align the speakers to the sub, then do the EQ and fine-tuning.

Regards,
Wayne

Your speakers frequency response is 45 Hz to 40 kHz, according to Denon...
If your system is primarily for stereo music listening you might set your sub/bass crossover at 45Hz to ~55Hz...
If your system is primarily for AudioVideo you might set your sub/bass crossover at ~80 Hz as suggested by both Dolby and THX...

ddude003 said:

Your speakers frequency response is 45 Hz to 40 kHz, according to Denon...
If your system is primarily for stereo music listening you might set your sub/bass crossover at 45Hz to ~55Hz...
If your system is primarily for AudioVideo you might set your sub/bass crossover at ~80 Hz as suggested by both Dolby and THX...

Click to expand...

Thanks for the tips, it is audio,video, games, I was using my old subwoofer from Genius 5.1 sound system and I had 80Hz on subwoofer and 65Hz on mains, seemed to work well and boosted some nulls in 60Hz range that subwoofer could not deliver to my LP, tomorrow I will begin experimenting with sub placement and measuring, really excited have to work today

So new subwoofer arrived, I have tested my entire room, changing listening positions, sub placement, all while measuring each position. Interestingly, I got best response when I face subwoofer cone directly into the corner of my room diagonally across from me. Any other positions had extreme nulls either in crossover region or low-end (below 35Hz). So this is best I think I can get out of this room.

I measured what I could think of, best response was at 80Hz/24db slope sub facing corner. Crossover in SVS app is set to 80Hz/24db slope, and I decided to not put any crossover on my mains. Using frequency generator and going by 1Hz, I determined they can produce sound loud enough and without distortion from around 55Hz, so I applied simple graphics equalizer on L+R speakers and put -50db on all frequencies below 53Hz or so, 55Hz and above mains get full signal, all of this is applied in final measurement "80Hz 24db eq.mdat" which also include my attempt at equalizing.

But I am having little trouble with those dips. Let's say I have -10db at 50-60Hz from 75db to 65db. All other frequencies are above 75db. How do I set the equalizer to drop everyhing to 65db (where 50-60Hz is) so I don't have to boost anything? It always takes the dips with entire curve.

Is it also possible to determine how the room needs to be treated, or even whether it could be, from the measurements?

I have included all my measurments.Thanks for reading and tips

Are using a windoz PC or Mac as your main platform to drive this Sound Blaster X4? What software do you use to apply a "simple graphics equalizer"? Is there some reason you aren't using a Parametric EQ? You might read about the differences, as some of your issues may be better solved with PEQ...

It would be better to measure each L and R speaker separately...

As for those dips, they may be mostly room modes... You can use the Room Sim function of REW that will estimate where your room modes would occur... Or https://amcoustics.com/tools/amroc... Are you low passing your new sub around where you are rolling off your mains?

Bass traps are crucial for absorbing low-frequency sound waves that cause room modes, especially in corners. Consider using thick, broadband bass traps or tuned traps for specific frequencies... Wide-band absorption panels strategically placed can help reduce reflections and mitigate modal behavior, particularly in the mid and high frequencies... This is a good place to start understanding Bass trap placement... http://arqen.com/bass-traps-101/placement-guide/ You can build your own or get some from https://www.gikacoustics.com/ or many others...

ddude003 said:

Are using a windoz PC or Mac as your main platform to drive this Sound Blaster X4? What software do you use to apply a "simple graphics equalizer"? Is there some reason you aren't using a Parametric EQ? You might read about the differences, as some of your issues may be better solved with PEQ...

It would be better to measure each L and R speaker separately...

As for those dips, they may be mostly room modes... You can use the Room Sim function of REW that will estimate where your room modes would occur... Or Are you low passing your new sub around where you are rolling off your mains?

Bass traps are crucial for absorbing low-frequency sound waves that cause room modes, especially in corners. Consider using thick, broadband bass traps or tuned traps for specific frequencies... Wide-band absorption panels strategically placed can help reduce reflections and mitigate modal behavior, particularly in the mid and high frequencies... This is a good place to start understanding Bass trap placement...You can build your own or get some from or many others...

Click to expand...

Yes, those are room modes. I am on Windows using EQApo with Peace ParametricEQ. I am applying GEQ on L+R and PEQ from REW AutoEQ on All channels, system-wide. I am downmixing from 5.1 to 2.1 using Peace command window, with these values:
Copy: L=0.33*L+0.33*C+0.33*RL+0.134*RR
Copy: R=0.33*R+0.33*C+0.33*RR+0.134*RL
Copy: SUB=0.35*R+0.35*L+0.17*SUB
I am not using any high-pass on mains, they go full range from 55Hz, subwoofer is low-passing 80Hz/24db through SVS app.
Aren't bass traps for really low frequencies? Will full-range bass traps treat the room modes that I deal with? and I guess I would have to cover the corner from floor to ceiling.


Room modes:

I think something like the GIK Soffit Traps might take care of some of that... You would have to contact GIK to get a better idea given what they think... They give free advise...

I'm not an expert on EQApo or PeaceParametricEQ... I just think it may be that the GEQ you are cutting with may be adding two wide of a cut that may be stepping on the PEQ... Even 32 Graphic Sliders does not give you much resolution down low where you are needing it...
Something else to think about would be Convolution... Doesn't APO or Peace do Convolution? And there are couple of methods that AVNirvana members have cooked up using REW to create FIR filters...

I was having trouble understanding your mixing commands, noticed that you did not end up with 100%, so I ran it through an AI to explain what you are doing... The AI thinks your down mixing commands may lead to clipping and/or distortion...

And since this is all being mixed down to 2.1 you might try moving the low pass on you sub down to around where your mains start to roll off...

Below the room transition frequency or Schroeder frequency, typically between around 100 and 250 Hz, the room acts as a resonator, and above the Schroeder frequency, as a reflector and diffusor of sound...

This master class in Digital Room Correction is a worthwhile watch...

Getting back to your mixdown commands... After some more reading and asking an AI questions... I think things should add up to 100%...
for instance "Copy: L=0.33*L+0.33*C+0.33*RL+0.134*RR" the 0.33+0.33+0.33+0.134= 1.124... I think you really want this to add up to 1.00... And the extra 0.124 might cause clipping and/or distortion... This for the left and right channels... As for the Bass command:
"Copy: SUB=0.35*R+0.35*L+0.17*SUB"... My take is that you are not using enough of the original 5.1 bass signal and adding too much left and right to that... I would have thought something more like 0.25 left and 0.25 right with 0.5 original bass... I could be way off in my take on all of this...

P.S As an analyst this is intriguing...