How do you EQ / treat this room?

[PK1]

Part of my question is related to EQ capabilities of REW, so hopefully this is the right place for this question. I am very new to REW and all things related to treatment and EQ, and I am working through the learning process. My system is a Mac Mini as the music source (Apple Music) => Denafrips Iris DDC => Pontus II DAC = Ladder Bach pre-amp => Arcam PA240 power amp => CSS 1TD-X speakers and a pair of REL T7X subs connected through the high-level connection. I am using the SoundSource app in the Mac Mini to apply my correction filters.

My listening room is 23' x 17' (7m x 5m) and is located on the second floor "mezzanine" type which is partially open to downstairs on the right side, and to the left if has a lot of windows - so very asymmetrical. In addition, the room layout is such that my set up is a little closer to the left wall (windows). I have a rudimentary hand sketch that I have attached to show the rough layout. Unfortunately moving the set up around isn't an option, so I have to work with this layout.

I ran measurements through REW with both L+R speakers and applied filters through SoundSource, which helped, but I feel that I can do better. I then ran measurements for each of L and R separately, which is shown below (green line is the left speaker, blue is right). Most of the "issue" is in the bass range, things seem pretty OK above ~110-120Hz. Note that I ran these measurements with the subwoofers off, this is the speakers only. I will bring the subs in the equation so as to not complicate things further for now, for now I want to figure out what my best next step should be for the lack of symmetry.

My question is:

Is there a way to apply EQ filters to each channel individually? If so, how do I do it? I know that room treatment should be part of this equation as well, but I have a hard time imagining how I would apply treatment considering that on one side I have a lot of open space and on the other side windows that I cannot apply treatment to, but welcome any suggestion. To be clear, there is "some" wall space on the window side, but either too low or too high (below and above the windows), with a few feel of wall space in the center of the wall which is a little behind my listening position.

 

[Wayne A. Pflughaupt]

My question is:

Is there a way to apply EQ filters to each channel individually? If so, how do I do it?

You would have to determine that from the manual of your equalizing device or software.

There is not much use in equalizing the lows of the main speakers if subwoofers will be used. It is best to measure and equalize with the subwoofers in operation.

Regards,
Wayne

 

[PK1]

There is not much use in equalizing the lows of the main speakers if subwoofers will be used. It is best to measure and equalize with the subwoofers in operation.

Thanks for the response.

Your comment above takes me to my next question: I am trying to wrap my head around how running the measurements with my subs running will make my speakers behave given the type of connection that I have. REL recommends to connect their subs using the high-level connection, which effectively means that there won't be a frequency crossover to the subs, and the main speakers run at their full range and the sub will overlay the bass on top of whatever the main speakers can produce. In a typical LFE or crossover connection, the low frequencies are directed to the sub while the speakers are then tasked with playing the higher frequencies.

With my "high-level" connection, I am trying to understand how the system would behave if I run my measurements and filters in REW with the subs operating: REW would measure lower frequencies and think that the main speakers can produce lower frequencies than they actually can, and since there isn't a crossover the corrections may try to push the main speakers to play lower than they are capable of causing distortion or other issues.

I am either completely misunderstanding this or overthinking it, but either way I have a hard time figuring out the best way to run the measurements (with or without subs) given how my subs are wired. Any thoughts on this?

 

[JStewart]

The dip around 100Hz is likely, at least in part, due to speaker boundary interference.

Speaker Placement 101: Is Speaker-Boundary Interference Killing Your Bass?

Not hearing enough bass through your monitors? The distance between your room boundaries and speakers has a huge impact on your bass performance. This tutorial will show you specific strategies for placing your speakers to get a balanced bass response.

arqen.com

100Hz has a quarter wavelength of 2.8 feet and the calculations are never 100% exact because walls are rarely 100% reflective.
Also, eyeballing the speaker diagram, it appears the distance to the front wall is very close to the same distance to the sidewall. If that’s true the it’s affecting the same frequency even more, in this case areound 100Hz.

The linked article above will have some solutions.

For speaker placement you might consider this placement advice, if possible. Scroll/navigate to “Listening Room Relationships Expressed in Golden Ratio”

Speaker Placement | Cardas Audio

The Cardas Speaker Placement Guide. Setting up speakers in a golden ratio, golden cuboid, golden trapagon room, etc.. Speaker placement calculators.

www.cardas.com

Regardless of how you plan to align the subwoofer to the mains you will benefit from having smoothest response you can get on the mains because even with a 24dB per octave crossover filter there is audible contribution from both speakers for an octave.

If you’d like suggestions as to how to incorporate EQ on individual channels then we’d need to know more about your sources and playback system.
And if you haven’t already read it somewhere, EQ is not (very) effective with SBIR.

 

[PK1]

@JStewart thank for the articles. I only scanned them for now but will do some more thorough reading a little later, very helpful. I realized that I hadn't provided the distance between the speakers and the back wall, which is about 3 ft from the front face of the speakers to the back wall (35" to be exact). Although the sketch is nowhere near to scale, you are correct that the left speaker is about the same distance to the side wall front (center of speaker is about 42" to the side left wall) than the rear wall. What I haven't shown on the sketch is the location of the subwoofers, which is right next to each speaker on the inside (left sub is located to the right of the left speaker, and the right sub to the left of the right speaker - very close to both speakers).

With regards to your question about my sources and play back, let me provide some additional information, please let me know if I have left out anything of importance. You did mention SBIR is hard to correct with EQ, but still helpful to know if I can EQ individual speakers in case it comes handy in the future:

- Music source: Mac Mini streaming music through the Music app. Through the searches and readings that I have done trying to figure out how to apply EQ filters to a Mac, I learned that the SoundSource app has this capability (https://rogueamoeba.com/soundsource/). I bought the app yesterday and installed it, and it uses numerous plugins for Audio Units, one of which is the Mac's AUNbandEQ, which is also a filter output format in REW. I exported the filters from REW in a text file, then manually entered the parameters into the AUNbandEQ plugin in SoundSource (a pain!), but it worked
- My Mac is connected vis USB to a Denafrips Iris DDC
- The DDC's I2S out is connected to the I2S in of a Denafrips Pontus II DAC
- I then use the XLR out of the DAC to the XLR in of the pre-amp (Ladder Bach)
- Then XLR out to the power amp (Arcam PA240)
- Main speakers are CSS 1TD-X and subs are REL T7X

Did I leave anything of importance out?

 

[Wayne A. Pflughaupt]

With my "high-level" connection, I am trying to understand how the system would behave if I run my measurements and filters in REW with the subs operating: REW would measure lower frequencies and think that the main speakers can produce lower frequencies than they actually can, and since there isn't a crossover the corrections may try to push the main speakers to play lower than they are capable of causing distortion or other issues.

Most likely that is not how things will work. REW will show response of the combined output. It can’t tell one speaker from another.

You’re really at a disadvantage using the high-level input, as it appears it gives the sub no level adjustment to help get a proper blend with the mains.

It’s also a disadvantage to run both the mains and subs full range, as that it will “dumb down” the overall system extension to that of the lesser performer, that being the main speakers in this case. Judging form specs at the REL site, which shows the T/7x extension at 30 Hz, and your in-room graph, you will have four speakers operating down to 50 Hz, but only two operating between 50 Hz and 30 Hz.

Here’s an old post from Home Theater Shack explaining the situation and result, with graphs to back it up (see post #15).

If you decide to keep the system in its current state, with both mains and subs running full range, it’s best to go with the common advice given here for people using multiple subs in different locations in the room. That being to equalize them all as if a single unit. As long as you don’t apply any (or much) EQ boost below 50 Hz, the mains should be okay.

Regards,
Wayne

 

[ddude003]

You did mention SBIR is hard to correct with EQ, but still helpful to know if I can EQ individual speakers in case it comes handy in the future:

There are any number of plugin EQs that will individually, or in combination, EQ the Left and/or the Right stereo channels... And since you seem to have a plugin host (SoundSource) the choices are only limited by your imagination and your pocketbook... Pulsar gml 8200 emulation anyone...

As far as how to integrate your subs, I would go with the suggestions of @Wayne A. Pflughaupt and @JStewart... Set your subs up so you can control gain and crossover capability... Noting stopping you from running your mains as full range... That's how I roll...

 

[PK1]

Thank you all! With all the reading I’ve done, I occasionally start to think “ok, I think I’m getting this”, and then a question pops up making me realize how much I don’t know…

So here’s a clarification on the Rel’s high input level connection as I’m not sure if I had explained it clearly enough: I can adjust both the crossover and gain on the subwoofer, it can be done manually with the levels in the back of the sub which I have done by ear and “feel” (if I remember the adjustable crossover range is from 30Hz to 120Hz). What I had meant was, there is no crossover anywhere cutting off the lower frequencies of the main speakers. So effectively with this setup the main speakers run their full range, and with manual adjustment of the crossover and gain of the sub, one can have the sub fill in the lower frequencies. So in my case my mains go as low as 50-ish Hz, and then I could set the sub play frequencies around 50Hz and below. This is how Rel recommends connecting the subs (high level input) and tuning them (by ear), and I followed their instructions.

Did the above clarify things or did you already understand this correctly and still recommending that I think about a different connection?

 

[JStewart]

Did the above clarify things or did you already understand this correctly and still recommending that I think about a different connection?

Nope, you’re on the right track to use what you have the best way possible. Only you will be able to say if you’ll be happy with the final outcome.

If you’re able, do see if you can improve the response of the left speaker with change of position. That will really help with the subwoofer integration. While you can now EQ the left and right channels separately, you don’t have the flexibility to EQ the subs and mains separately so best response pre-EQ will make things better.

Having the subs located next to the speakers as you do will be good for the time alignment of the subs and mains with your current kit.

Let us know if we can help more as you work through it.

 

[PK1]

Nope, you’re on the right track to use what you have the best way possible. Only you will be able to say if you’ll be happy with the final outcome.

If you’re able, do see if you can improve the response of the left speaker with change of position. That will really help with the subwoofer integration. While you can now EQ the left and right channels separately, you don’t have the flexibility to EQ the subs and mains separately so best response pre-EQ will make things better.

Having the subs located next to the speakers as you do will be good for the time alignment of the subs and mains with your current kit.

Let us know if we can help more as you work through it.

Thanks. I’m playing with different arrangement, starting with speaker locations - which is hard given my room and furniture - but working on it.

I’m sure I’ll have more questions later, but do appreciate all the help so far!

 

[ddude003]

If you use a Timing Ref you can precisely aline your front left and right speakers... This, in my opinion, is one of the most important things you can do to start to get thing right... Next would be to get your subs in order... Crossover and gain to match your main speakers... And time aline your subs to each other and your mains... Once you get this done, you can add a bit of a room curve and layer on EQ to taste...

 

[PK1]

If you use a Timing Ref you can precisely aline your front left and right speakers... This, in my opinion, is one of the most important things you can do to start to get thing right... Next would be to get your subs in order... Crossover and gain to match your main speakers... And time aline your subs to each other and your mains... Once you get this done, you can add a bit of a room curve and layer on EQ to taste...

By Timing Reference do you mean the option in REW during measurements? The one that emits a little chirp before and after the sweep? If so I have used that in my measurements but have no idea how to use it.

How do I align the speakers with that?

 

[ddude003]

By Timing Reference do you mean the option in REW during measurements? The one that emits a little chirp before and after the sweep? If so I have used that in my measurements but have no idea how to use it.

How do I align the speakers with that?

Yes, the chirp is the timing reference...

The first part of this video...

and its accompanying tutorial document https://drive.google.com/file/d/17BwTGv933w4id3B3PFHy2zjyijtgZLDX/view describe how to take the first steps of speaker placement and measurements down this time align rabbit hole... Your done at the end of step 13...

 

[JStewart]

By Timing Reference do you mean the option in REW during measurements? The one that emits a little chirp before and after the sweep? If so I have used that in my measurements but have no idea how to use it.

How do I align the speakers with that?

I’ll provide a shorter answer.
A timing reference is used and necessary to calculate relative delay or phase between speakers.
If your main speakers are exactly equidistant from your ears then it’s moot.
Subwoofers can be aligned by phase with the mains at the XO or with each other as well as the mains in a mono dual sub configuration, but only when you have the means to adjust delays for each speaker separately. In your case that is 4 speakers consisting of each main and each sub.
Your subs are adjacent to your mains and I assume you are using the same amplification via speaker level connection to the subs. This means the subs are not using internal DSP which might delay them relative your mains, which is good because otherwise they would need moved closer to you than the mains to maintain relative timing.
Well, I guess that wasn’t so short after all. Hope it makes sense. If not, I’d be happy to clarify anything I’ve not expressed well enough.

 

[JStewart]

How do I align the speakers with that?

In REW by using the Alignment Tool along with measurements taken with a timing reference.

 

[ddude003]

If your main speakers are exactly equidistant from your ears then it’s moot.

Emphasis on _exactly_ and often in room physical measurements are not _exactly_ equal to acoustic measurements... Is my OCD showing?
And if @PK1 reads the Optional part of tutorial section 13 there is even more magic to be had...

 

[JStewart]

Is my OCD showing?

Sure, but it’s a gift, not a fault.

 

[PK1]

Thanks guys, I watched the video and will need to watch it again (or a few times). very useful video, it’s great that he also has the instructions in print. One thing I need to figure out is how to apply all of these corrections. I don’t use Roon or anything sophisticated, and the only system-wide Mac-based EQ that I’ve been able to find is SoundSource which has its limitations.

 

[PK1]

Is my OCD showing?

Everybody else measures speaker placement to the mm, and toe-in using a protractor, right? Perfectly normal?

 

[ddude003]

You might look into something like BlackHole https://github.com/ExistentialAudio/BlackHole and a simple Plugin Host maybe like https://accuratesound.ca/hang-loose-host-hlhost/ plus a Convolver Plugin... https://www.audiosciencereview.com/...ds/a-comparison-of-convolution-engines.43290/ or any number of other Stereo Equalizer Plugins where you can separately EQ left and right channels as well as separately adjust the gain of each channel...

You would be surprised at what is considered normal in this community...

 

[JStewart]

Everybody else measures speaker placement to the mm, and toe-in using a protractor, right?

You mean they don’t?

 

[ddude003]

Since I already have all of the above pieces (BlackHole, HangLoose Host, HangLoose Convolver, and various Stereo EQ plugins) I configured them to utilize the MacOS internal sound system... Yes, on the Mac that means all sound... And ran the Apple Music app... It all worked as expected... All sound from any app now has the room correction and additional Stereo EQ... I normally use Audirvana as it is my favorite player and plugin host or use Reaper a DAW which is also a player and plugin host... And I thought using BH, HLH, HLC and P8200 on the overall system sound was a fun way to prove my above thesis...

 

[PK1]

Since I already have all of the above pieces (BlackHole, HangLoose Host, HangLoose Convolver, and various Stereo EQ plugins) I configured them to utilize the MacOS internal sound system... Yes, on the Mac that means all sound... And ran the Apple Music app... It all worked as expected... All sound from any app now has the room correction and additional Stereo EQ... I normally use Audirvana as it is my favorite player and plugin host or use Reaper which is also a player and plugin host... And I thought using BH, HLH, HLC and P8200 on the overall system sound was a fun way to prove my above thesis...

if you lived close by I’d offer a few (expensive) beers and other perks for you to come and spend a couple of hours with me to help me figure all this out!

This hobby is becoming a full-time job

 

[ddude003]

Thank you for the offer... Save that beer money for some more kit...

From the looks of it you have a pretty nice system... You may as well get the best sound you can from it... Its not a job, its an adventure...

We are all here to help... Most of us anyway...

 

[VinceHoffman]

Why doesn't the OP simply rotate his system 90 degrees so that the loudspeakers are set up in front of the longer 23' left wall? This would allow the speakers to operate in an acoustically symmetrical space with regards to the front and sidewall boundaries, avoiding large scale differences between the left and right loudspeakers' low frequency response curves...