Challenging room. Looking for 2.1 desk setup placement suggestions.

[Tupisac]

I'm looking for some help with optimal placement for a desk setup. Speakers will be mounted to a wall and listening position around 150 cm from speakers. I will use a sub too. My room is basically a square but with slanted roof. There is a door at the bottom right corner (looking from the top view) and a window with a balcony at the bottom left. Slanted roof is over the upper half. Walls are made out of bricks, with left and top one being the external ones.

I only care about low frequencies for now. I'll throw acoustic treatment at the rest. Currently I struggle to get anything below 40 Hz out of my sub. There is a huge peak around 50 Hz too.

I also wonder how accurate is REWs room simulator for such shape.

 

[EERecordist]

You are on the right track with REW and what ever detailed EQ software you have available. Understand the Spinorama of your speakers and orient your speakers to have your listening position in the near field sweet spot.

Low frequencies take a lot of energy and a lot of air movement. So for lows you may need a large and expensive sub. You might experiment with a Subpac/equivalent or a game chair shaker.

 

[Ruediger]

I only care about low frequencies for now. I'll throw acoustic treatment at the rest. Currently I struggle to get anything below 40 Hz out of my sub. There is a huge peak around 50 Hz too.

It's not a big room and my first thought is if the subwoofer can do what you want. A small one might struggle. But something decent should fill that room easily.

A peak evolving at 50hz and needing correction can be a separate topic and also be present when you use a bigger subwoofer.

 

[janbth]

I also wonder how accurate is REWs room simulator for such shape.

I have an L-shaped listening room and find that the REW room simulator is OK-ish for predicting the lowest room modes, but don’t expect the frequencies to be accurate. To get a better prediction, there are tools for non-rectangular rooms out there, e.g. Amroc Pro. It’s free for the 5 lowest modes, and gives an informative visualization of the standing wave pattern for each mode.

 

[Tupisac]

It's not a big room and my first thought is if the subwoofer can do what you want. A small one might struggle. But something decent should fill that room easily.

A peak evolving at 50hz and needing correction can be a separate topic and also be present when you use a bigger subwoofer.

I have an LSR310S. On paper it goes down to 26 Hz (-3 dB).

The problem is that at my current listening position it just drops around 50 Hz like a brick and there is nothing salvageable below 40 Hz:

REW simulator shows similar thing:

Looks like I'm screwed. Moving the sub along the front wall in the sim doesn't do much. The only possible solution according to REW is an opposite corner. I guess I could route the cables but I'm afraid of the delays. I play guitar and adding over 10 ms of delay to speakers on my DSPmini is already noticeable.

 

[Tupisac]

I have an L-shaped listening room and find that the REW room simulator is OK-ish for predicting the lowest room modes, but don’t expect the frequencies to be accurate. To get a better prediction, there are tools for non-rectangular rooms out there, e.g. Amroc Pro. It’s free for the 5 lowest modes, and gives an informative visualization of the standing wave pattern for each mode.

Unfortunately it doesn't do the slanted roof. I wonder how much influence it has for such low frequencies.

Here are the calculations:

 

[Ruediger]

I have an LSR310S. On paper it goes down to 26 Hz (-3 dB).

Do you cross over at no more than 80hz?

It's what I'd call a small subwoofer. Good options as it looks like, also 10". But just 200w. The paper seems optimistic.

Maybe you have the opportunity to try a different one.

 

[Redacted]

Measuring, REW etc, is one thing, but "room calculation tools" are another. I'm sure it's interesting to see what a tool predicts in terms of standing waves etc.
I guess a really top tool would let you enter all your furnishing details - size, position, what they are made of, and whether walls are solid or dry lined - and a thousand other things that might tune the model. But I'm not sure if there is a good tool that does all this.

To me, you have two choices:
1) Put your speakers where you wife says to avoid strife and get your mic out, do the measurements and work around the findings, or:
2) Experiment with manual positioning of the speakers in several possible locations and mess with relative volumes of subs and mains and set XO point for each sub yourself. (you may find 2 subs make things easier).

 

[Tupisac]

The paper seems optimistic.

I actually measured it directly at the port and the driver when I got it. I though it was broken or something. But it does go as deep as advertised. It's just my room and listening position. I'm not sure if bigger sub will make that much difference. REW simulator doesn't show any improvement with lower -3 dB point or if it's ported or sealed.

I experimented with 100, 80 and 50 Hz crossover (high & low pass), with various delays calculated from REWs alignment tool. It does make a difference but only for frequencies over 50 Hz.

 

[whazzup]

I actually measured it directly at the port and the driver when I got it. I though it was broken or something. But it does go as deep as advertised. It's just my room and listening position. I'm not sure if bigger sub will make that much difference. REW simulator doesn't show any improvement with lower -3 dB point or if it's ported or sealed.

I experimented with 100, 80 and 50 Hz crossover (high & low pass), with various delays calculated from REWs alignment tool. It does make a difference but only for frequencies over 50 Hz.

Just curious, how are you connecting the sub to your (I assume) Windows system? Onboard? USB Dac? Configured as 2.0 or 2.1 channel in Windows? Using EqAPO + Peace?

 

[Tupisac]

To me, you have two choices:
1) Put your speakers where you wife says to avoid strife and get your mic out, do the measurements and work around the findings, or:
2) Experiment with manual positioning of the speakers in several possible locations and mess with relative volumes of subs and mains and set XO point for each sub yourself. (you may find 2 subs make things easier).

Good thing is that this is my home office slash man cave. Bad thing is that it is already furnished to the brim and everything fits like a puzzle. I just want to check things virtually as far as I can to see it the major redecoration is even worth it.

Unfortunately second sub doesn't seem to do much for the 50 Hz drop in REW simulator.

 

[Tupisac]

Just curious, how are you connecting the sub to your (I assume) Windows system? Onboard? USB Dac? Configured as 2.0 or 2.1 channel in Windows? Using EqAPO + Peace?

I'm on a mac with Motu M2 interface. The outputs from Motu (2.0) are plugged into the t.racks DSP 4x4 Mini where I set the filters, delays and route audio into 3 channels.

 

[whazzup]

I'm on a mac with Motu M2 interface. The outputs from Motu (2.0) are plugged into the t.racks DSP 4x4 Mini where I can set the filters, delays and route audio into 3 channels.

This is based on my own experience, not sure if it applies, but when I ran my sub with the Xonar U7 usb dac (yellow line below), which gives only max 1Vrms rca out, my sub will grossly underperform (down by >10db), as opposed to running off my onboard realtek.

Amir's review of the Xonar U7:

Review and Measurements of Asus Xonar U7 MKII ADC/DAC/HP

This is a review and measurements of the Asus Xonar U7 MK II multi-channel DAC, Headphone Amplifier and Analog to Digital (ADC) converter. A member overseas prompted me to purchase this unit to test by donating to the forum nickel jar. :) At just US 90 on Amazon with prime shipping, this is...

www.audiosciencereview.com

Problem could lie with the t.racks since M2 is giving full 2Vrms.

 

[Tupisac]

This is based on my own experience, not sure if it applies, but when I ran my sub with the Xonar U7 usb dac (yellow line below), which gives only max 1Vrms rca out, my sub will grossly underperform,

Interesting. But in my case it all goes via balanced connections and there is plenty of headroom left. Sub's volume is set around 50%.

Your graph looks oddly familiar with this sudden 50 Hz drop. Room dimensions look pretty close too.

 

[Tupisac]

Problem could lie with the t.racks since M2 is giving full 2Vrms.

Yes, I'm aware of that problem. I have Motu's volume set around 1 o'clock. So far I haven't seen any clipping.

 

[whazzup]

Interesting. But in my case it all goes via balanced connections and there is plenty of headroom left. Sub's volume is set around 50%.

Your graph looks oddly familiar wit this sudden 50 Hz drop. Room dimensions look pretty close too.

Mine's an 8 inch. On paper they say it goes to 35hz too.
Maybe try hooking either direct to M2 or to the Mac and see if at the same 50% volume there's any change to your sub output. Anyway that's all the ideas I have. But I think generally 8-10 inch subs top out around the same range unless they were specifically designed to be driven way harder to 30hz.

 

[Tupisac]

Measuring, REW etc, is one thing, but "room calculation tools" are another. I'm sure it's interesting to see what a tool predicts in terms of standing waves etc.
I guess a really top tool would let you enter all your furnishing details - size, position, what they are made of, and whether walls are solid or dry lined - and a thousand other things that might tune the model. But I'm not sure if there is a good tool that does all this.

Tbf REWs predictions look close enough to measurements in terms of major drops at low frequencies, even with very simplified room shape.

What I would love to check next is room treatment. Like if it's even worth investing in big bass traps. Or tuned membrane ones.

 

[whazzup]

@Tupisac
Oh by the way, what I did with my sub, is to go full volume, then chop down the peaky 50hz to try and get some usable 40hz. Which in my case, I was only able to do after figuring out the usb dac low output issue. Hope it helps.