Need advice on using full range main speakers and a single sub as a multi-sub setup

[SinaHakman]

Hi,

I need your kind advise on using bass management.

My listening room is an L shaped space with a volume of approx. 125 m3 (4400 cubic ft). My main speakers are KEF R11s which I am very happy with. I use Dirac Live 3.0 on my MiniDSP Studio. It handles nearly all the room mode peeks under the schroeder frequency. The frequency response of the left speaker goes down to roughly 30 Hz in a 3 dB window. Right one goes down to approx. 40 Hz in 3dB window.

I have a medium sized couch that I normally sit while enjoying music. Although the peeks are mostly well controlled over the listening area, I have a few nasty dips across the area which cannot be corrected by room EQ. I would like to remedy this with a multi sub combination. However, this room being our living room I do not have much chance and space to place two subwoofers (being L shaped doesn’t help either).

Is there any way that I can utilize the main speakers and single sub to have a more homogeneous bass response from my listening area? For example, as commonly implemented with two-sub placements, if I place the sub near the rear wall can the main speakers act as the other sub near the front wall?

What do you think? Thanks in advance...

 

[stevenswall]

Yes, but to do this with Dirac requires Dirac Live Bass Control, which is only available on the Monoprice HTP1 for $4000, or you'd have to use something else that supports that, ballpark $12,000-20,000.

 

[Ron Texas]

Get two subs, high pass the mains.

 

[johnp98]

Certainly you could add a sub to this! The main speakers can also act as a low frequency source so in your case you could probably get a pretty flat response down to the 30s and then would be relying on the single sub and room interactions for everything below 30hz.

Adding more subs would even out the response even more, but you have to start somewhere

 

[SinaHakman]

Yes, but to do this with Dirac requires Dirac Live Bass Control, which is only available on the Monoprice HTP1 for $4000, or you'd have to use something else that supports that, ballpark $12,000-20,000.

Monoprice is unfortunately way over my budget.
I was thinking about integrating the sub with the mains as best as I can using MiniDSP Studio and then applying Dirac Live room EQ. I guess it won't be as good as Dirac Live Bass Control but better than not having a third bass source (in addition to the mains).

 

[SinaHakman]

Get two subs, high pass the mains.

You're absolutely right. I know that would be the best way

KEF R11s are pretty good at low end response. I would feel guilty with cutting the low end after I paid that much for 40 kg speakers that towers in our living room.

 

[SinaHakman]

The main speakers can also act as a low frequency source so in your case you could probably get a pretty flat response down to the 30s and then would be relying on the single sub and room interactions for everything below 30hz.

Thanks for your encouragement.

Have anyone used Multi-Sub Optimizer software with one sub and two full-range mains?

 

[abdo123]

Yes, but to do this with Dirac requires Dirac Live Bass Control, which is only available on the Monoprice HTP1 for $4000, or you'd have to use something else that supports that, ballpark $12,000-20,000.

or the MiniDSP DDRC-88A (or the DDRC-88D if you're a SINAD chaser) for 1150$

https://www.minidsp.com/products/dirac-series/ddrc-88a

https://www.minidsp.com/products/dirac-series/ddrc-88bm

 

[johnp98]

Thanks for your encouragement.

Have anyone used Multi-Sub Optimizer software with one sub and two full-range mains?

I have never used MSO as I have found that manually doing it is not too complicated.
If you look for guides on how to use REW time alignment that's most all you will need.
The general approach is:
1) Measure any and all subs independently (with timing 'cherp' from the speaker to allow rew to calculate time alignment)
2) Time align all subs so they function as a single unit. They should have increased output across the entire frequency range.
3) Measure speakers (with time alignment 'cherp')
4) Time align speakers to subs with measurements 1 and 3. There should be increased output across the entire overlap region (not technically a crossover, as both speakers and subs running a larger frequency range).
5) Set individual high pass filters on subs based on their location and desire to keep them unlocalizable (so one in the front often run significantly higher than ones behind or near field)
6) DSP if able (keeping in mind we want an upward slope / house curve).
7) Enjoy!

*for your case, you just have 1 sub, so you can skip step 2....but just incase you get future subs that's how you would add them

 

[SinaHakman]

Thanks @johnp98 This makes really good sense.

My budget and space allows me to start with a single sub and I'm pretty comfortable with REW, so I think I could do that. I need to acquire a sub, though.

Thinking about either SVS SB-1000 Pro, SB-2000 Pro, SB-3000 Micro or KEF KC62. As they seem to be the only sensible ones with good low end extension and small(ish) size. Any other suggestions?

 

[SinaHakman]

or the MiniDSP DDRC-88A (or the DDRC-88D if you're a SINAD chaser) for 1150$

Many thanks. I could probably go that way, if manual REW based adjustment doesn't work with one sub. I think, I'll try with one sub, and see if it will be enough.

 

[audio2design]

@SinaHakman,


How much flexibility do you have in placement of the main speakers? You didn't describe the dimensions of your room. That will give us a better idea of the room modes, possible placement options (if possible) and addition of subs. Depending on the compromise, two small subs may give you a flatter response, just not as deep at the same cost. It all depends what you are trying to achieve. I personally would not rely on the sub for deeper bass, not a single one, but as a way to flatten out the base response. Room correction can do wonders, but not all wonders, a flat listener response can mean peaks in other locations which can lead to decay issues, unexpected resonances (L-shapes can be nasty). Best results are always getting as close to flat as you can with speaker placement and more subs (properly placed) then using room correction to fix remaining issues.

 

[SinaHakman]

Thanks for your suggestions @audio2design. This will be a long reply, hopefully I won't get anyone bored.

How much flexibility do you have in placement of the main speakers?

Not much, I'm afraid. There are many restrictions due to the placement of windows and various other factors.

You didn't describe the dimensions of your room. That will give us a better idea of the room modes, possible placement options (if possible) and addition of subs.

Here's a pretty rough drawing of the space (in meters):

Speakers are at places marked with X, LP is the rough listening area.

I use Dirac Live with pretty good results from our main listening position. The average FR sampled across 12 points around the listening area is also pretty good (except a bass response issue below 30Hz on right channel):

However, if I compare the bass response at two separate positions in the listening area, the results are not that nice.
For Left channel:

For right channel:

If is far from even, more than 10dB at some frequencies!

I was just thinking to do the following (possibly naively):
- Hi pass mains from 46 dB upwards. As KEF R11 can produce down to 46Hz comfortably without the ports.
- Close the ports with supplied plugs to reduce distortion.
- Place a small sub, that can handle high 20s and above, hopefully somewhere that can help the FR response
- Determine XO point (with 24 dB/oct slope) as high as possible so that the sub is not identifiable, configure it using miniDSP SHD
- Apply Dirac Live to the combination with a +8dB Harman room curve

So the sub will cover between 25 to 46Hz, then from 46 to probably 80 run all speakers in paralel and over 80 Hz main speakers will take over. I could go for two subs but due to space and placement restrictions I want the smallest sub possible so that I can have more options for placement. That led me to consider KEF KC62. One sub is in my budget ballpark, but two subs will cost around 3000 EUR which will exceed my budget. Alternatively, I considered SVS SB-3000 Micro but it is not available where I am, at least for now.

Maybe I'm wishing for something unachievable. As I do not have a sub and I can get one for trial in my country, I cannot test my hypothesis and looking for advise!

Many thanks again.

 

[audio2design]

It could be worse. 50-100Hz is pretty good. Some issues in that one spot from 30-40Hz, but some serious issues from 100-200Hz and 300-400 approx. Those may be more detrimental overall and are purely the mains. I would be playing around with speaker placement. Even small movements may give you some significant changes in these areas. I would be looking at heavy first reflection control on the 6.7m wall as well to even out the two sides.

 

[sweetchaos]

Thinking about either SVS SB-1000 Pro, SB-2000 Pro, SB-3000 Micro or KEF KC62. As they seem to be the only sensible ones with good low end extension and small(ish) size. Any other suggestions?

First 2 models were measured, but not the last 2. See my ‘subwoofer comparison’ spreadsheet for the analysis.

Lots of well-measuring subs are available, so it just depends on your budget, and availability.

 

[SinaHakman]

I'll play around with the placement, especially to correct the right speaker response. As you said it is not ideal in the 100-200Hz and 300-400Hz area. Many thanks.

 

[SinaHakman]

See my ‘subwoofer comparison’ spreadsheet for the analysis.

@sweetchaos Your subwoofer comparison spreadsheet was my bible while I was doing my research. Many thanks for your effort to put it together. That is the most useful document that is available. Absolutely great!