methodology and approach for subs and bass traps

Loheswaran

Well-Known Member
Dec 19, 2014
432
99
258
My builders have just completed my man cave in my loft.

It is in a triangular space that effectively measures 2 meters high - 5 meters wide, and 3 meters long.

the shape is such that the speakers must be placed on the longest wall.

I have had the walls and ceilings suspended on acoustic handers and the gaps are filled with rock wool. The Floor is suspended on 2 layers of Mass Loaded Vinyl. It has a laminated wood floor surface.

In the sides where the diagonal ceilings meet the floor I have space to put bass traps there.

I know I ain't gonna get super deep bass due to the small room size. I guess it is gonna be a 'small but perfectly formed' monitor set-up.

Now I am toying with the idea of putting Rockwool into the the corners, but I have read about diaphragmatic traps that can essentially be tuned to cover frequencies.

I want to apply some logic and method to my approach, which in terms of the main wall/floor/ceiling construction I have done thus far. So my questions are as follows:

1. Should I:
a. first set up my equipment with seating, stands and furniture then do. some frequency sweeps via a CD player and chart the characteristics, or
b. set up as above but use some clever software to play via my computer and system to do frequency sweeps and to measure echo and bass decay/reverberation?

2. With the above info:
a. custom build various bass traps/ treatment - if so would various materials help cover the relevant frequency range
b. buy ready made traps/treatment

3. Are subs gonna just cause more problems by overloading a small room with bass
 

Rodney Gold

Member
Jan 29, 2014
983
11
18
Cape Town South Africa
Set up , measure , apply physical treatment , then do DSP to clean it all up if you want or need to
Multiple subs will smooth the room .. excellent way to go for bass issues
 

Loheswaran

Well-Known Member
Dec 19, 2014
432
99
258
Set up , measure , apply physical treatment , then do DSP to clean it all up if you want or need to
Multiple subs will smooth the room .. excellent way to go for bass issues

Won't it be a case that the added subs will introduce bass that then overpowers the room? or is it the case that the subs fill out dips in the room modes?
 

LL21

Well-Known Member
Dec 26, 2010
14,411
2,509
1,448
Won't it be a case that the added subs will introduce bass that then overpowers the room? or is it the case that the subs fill out dips in the room modes?

I think the latter is true when the subs are set up right...and then with your first observation, you simply turn DOWN each sub because combined they can deliver big bass at lower volumes (and lower distortion). That is the theory anyway...the key is implementation as always!
 

DaveyF

Well-Known Member
Jul 31, 2010
6,129
181
458
La Jolla, Calif USA
I think the latter is true when the subs are set up right...and then with your first observation, you simply turn DOWN each sub because combined they can deliver big bass at lower volumes (and lower distortion). That is the theory anyway...the key is implementation as always!

Agree 100%.

Having just added a second REL sub to my system, I can say that the addition does tend to smooth out room modes...BUT...and this is what I found to be the biggie, it also adds a host of other issues that have to be dealt with!
I found the ‘Blending’ of two subs to be much more difficult than with one, and I also found the positioning to be far more critical! The ease of overloading the room increaseas greatly...and results in some music being unlistenable...that is until the exact dial in is achieved. Whereas it took me a few weeks to dial in one sub, it has taken me a few months to dial in two....to the point where they are invisible in the mix and with all music.
Although most dealers and sub manufacturers recommend multiple subs, I would suggest that unless one is willing to go through the extensive adjustments necessary to get them right ( and the time involved to do so), I’m not so sure it is the “go to” solution. Once dialed in, they are great, but what a headache:(
 

awsmone

Well-Known Member
Apr 6, 2014
1,616
513
435
Canberra Australia
Agree 100%.

Having just added a second REL sub to my system, I can say that the addition does tend to smooth out room modes...BUT...and this is what I found to be the biggie, it also adds a host of other issues that have to be dealt with!
I found the ‘Blending’ of two subs to be much more difficult than with one, and I also found the positioning to be far more critical! The ease of overloading the room increaseas greatly...and results in some music being unlistenable...that is until the exact dial in is achieved. Whereas it took me a few weeks to dial in one sub, it has taken me a few months to dial in two....to the point where they are invisible in the mix and with all music.
Although most dealers and sub manufacturers recommend multiple subs, I would suggest that unless one is willing to go through the extensive adjustments necessary to get them right ( and the time involved to do so), I’m not so sure it is the “go to” solution. Once dialed in, they are great, but what a headache:(

Agree that multiple subs are the way to go, to smooth bass

I would try the speakers in the room first before going down this root

Statistically you need a minimum of three subwoofers to flatten things out,
I am interested in your experience with 2 over one , I went from one to three to five subs so maybe I missed the ‘two’ issue... I am just speculating but if you had a symmetrical room, and symmetrical speaker and subwoofer set up, then if the two subs were in phase, the modes existing would be made worse, blending them could then be interesting

I read an interesting idea from a sound engineer, for sub set up, haven’t tried it, myself

Place the sub in your listening position and play bass heavy track, such as running bass guitar or plucked double bass

Move around the room, especially around the front wall, finding places where it sounds clearest and mark them with tape, then try the subs where you marked on your walk around

My third system I am just about to add subs to, so will try this technique then as an experiment, but interested if anyone has heard or tried this technique ...
 

DaveyF

Well-Known Member
Jul 31, 2010
6,129
181
458
La Jolla, Calif USA
awsmone, I think the size of your room is a major factor with adding subs to your system...and the number and size that will work best. In my very small room, appx 10X11, I can get away with two (2) at best. These subs have to be 'quick' and they have to be able to pressure the room, but not too much. Therefore, I have two REL 8" drivers...instead of say one 10" driver ( which I think would be too much for this space...most likely....even though two 8" drivers have more driver surface than one 10"). Going with three subs in this room would be a non-starter, IME. Like I posted above, getting two to work was much much more difficult than with just one. I had NOT realized the problems before starting on the add-on. While I ended up with better sound than with just one sub, the work involved was extremely frustrating and involved/lengthy.
 

Loheswaran

Well-Known Member
Dec 19, 2014
432
99
258
wave length

awsmone, I think the size of your room is a major factor with adding subs to your system...and the number and size that will work best. In my very small room, appx 10X11, I can get away with two (2) at best. These subs have to be 'quick' and they have to be able to pressure the room, but not too much. Therefore, I have two REL 8" drivers...instead of say one 10" driver ( which I think would be too much for this space...most likely....even though two 8" drivers have more driver surface than one 10"). Going with three subs in this room would be a non-starter, IME. Like I posted above, getting two to work was much much more difficult than with just one. I had NOT realized the problems before starting on the add-on. While I ended up with better sound than with just one sub, the work involved was extremely frustrating and involved/lengthy.

Isn't a problem that I have the fact that the room is simply too small to reproduce deep bass? or am I missing a trick here, or is it a case that one can drive the room - if that is the case what's the science behind this?
 

DaveyF

Well-Known Member
Jul 31, 2010
6,129
181
458
La Jolla, Calif USA
Isn't a problem that I have the fact that the room is simply too small to reproduce deep bass? or am I missing a trick here, or is it a case that one can drive the room - if that is the case what's the science behind this?


That depends a lot on how you define "deep bass". IME, every room ( at least in the typical home environment) has a limit to the bass wave that can be produced...cleanly. OTOH, getting the best from a sub system is possible in most rooms..however small. I believe the trick lies in matching the size of the sub/driver to the size of the room. The smaller the room, the smaller the sub, is a good general rule. I was concerned that adding a second sub to my very small room was going to be problematical...in regards to overdriving the room. This did prove to be an issue initially, but with a lot of experimentation and adjusting, I managed to overcome the problems. I think most anyone can do the same thing, but be prepared to a) know the room's limitations, b) experiment and experiment c) adjust frequently d) research the type and size of sub(s) that will most likely work in the space and with your mains. This doesn't mean automatically going for the biggest sub that your money can buy...like so many inexperienced a'philes like to do.All IMHO.
 

Al M.

VIP/Donor
Sep 10, 2013
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Greater Boston
That depends a lot on how you define "deep bass". IME, every room ( at least in the typical home environment) has a limit to the bass wave that can be produced...cleanly. OTOH, getting the best from a sub system is possible in most rooms..however small. I believe the trick lies in matching the size of the sub/driver to the size of the room. The smaller the room, the smaller the sub, is a good general rule. I was concerned that adding a second sub to my very small room was going to be problematical...in regards to overdriving the room. This did prove to be an issue initially, but with a lot of experimentation and adjusting, I managed to overcome the problems. I think most anyone can do the same thing, but be prepared to a) know the room's limitations, b) experiment and experiment c) adjust frequently d) research the type and size of sub(s) that will most likely work in the space and with your mains. This doesn't mean automatically going for the biggest sub that your money can buy...like so many inexperienced a'philes like to do.All IMHO.

Lots of things that I can agree with here. One word about large drivers in subs and small/medium sized rooms: Originally, in my recent upgrade, I would have wanted to buy JL Audio Fathom 110 subs (10 inch drivers). Yet these had been discontinued, so I went with the 12 inch driver version (Fathom 112v2). This worked fine in my medium sized room (24 x 12 x 8.5 feet), with some exceptions. Yet there a feature on the JL sub came in handy: the so-called 'LF-trim'. You can attenuate the output at the 24 Hz level up to -12 dB, and I did that, going to -8dB. Problem solved. Without that feature I would have been 'screwed' one some recordings, but JL Audio wisely included it, specifically stating benefits for small or medium sized rooms. And I still have deep, fast bass.

The JL Audio subs also have digital room equalization, where you pick up test tones with an included microphone at the listening seat, and the equalization evens out peaks and dips (not nulls, obviously). Works wonderfully. Highly recommended.
 

awsmone

Well-Known Member
Apr 6, 2014
1,616
513
435
Canberra Australia
I agree about tailoring the deep bass around 25 hz and lower
There is little musical content, but there is some “air” which brings in to focus some treble information , but I found the quantity of energy needed is quite low

As 25 hertz is around the quarter wave of 11 ft, there are a lot of average room dimensions that come into play around this point, therefore there is no need to overdrive them
I use REL approach to this , coupling with the room modes to lower the need of amplifier to run hard

In summary, it’s nice to have a little energy below this, but not much , plenty of room modes down this low, so attenuation is the safe option....
 

Loheswaran

Well-Known Member
Dec 19, 2014
432
99
258
I agree about tailoring the deep bass around 25 hz and lower
There is little musical content, but there is some “air” which brings in to focus some treble information , but I found the quantity of energy needed is quite low

As 25 hertz is around the quarter wave of 11 ft, there are a lot of average room dimensions that come into play around this point, therefore there is no need to overdrive them
I use REL approach to this , coupling with the room modes to lower the need of amplifier to run hard

In summary, it’s nice to have a little energy below this, but not much , plenty of room modes down this low, so attenuation is the safe option....

I keep being told how good REL subs are, but they seem to lack adjustments - how is this in the real world so to speak
 

Al M.

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Sep 10, 2013
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I keep being told how good REL subs are, but they seem to lack adjustments - how is this in the real world so to speak

Which is a main reason why I went with JL Audio subs, because of adjustability.
 

microstrip

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May 30, 2010
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Which is a main reason why I went with JL Audio subs, because of adjustability.

IMHO the best of the JLAudio V2 is the auto-calibration. Great feature!
 

Loheswaran

Well-Known Member
Dec 19, 2014
432
99
258
Not sure if this next question should have a separate thread, but if I have a suck out at a particular frequency - doesn't it mean that if I equalised my bass to put more volume into the said frequency - wouldn't it also just suck out?
 

Al M.

VIP/Donor
Sep 10, 2013
8,681
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963
Greater Boston
IMHO the best of the JLAudio V2 is the auto-calibration. Great feature!

Absolutely! I love it too, and it actually works: if I calibrate with the microphone at a different listening position and then move back to the original one, the bass response is audibly different than if I calibrate at that original listening position.
 

Dennis Foley

Member
Sep 11, 2019
11
12
10
71
Los Angeles, CA
www.acousticfields.com
My builders have just completed my man cave in my loft.

It is in a triangular space that effectively measures 2 meters high - 5 meters wide, and 3 meters long.

the shape is such that the speakers must be placed on the longest wall.

I have had the walls and ceilings suspended on acoustic handers and the gaps are filled with rock wool. The Floor is suspended on 2 layers of Mass Loaded Vinyl. It has a laminated wood floor surface.

In the sides where the diagonal ceilings meet the floor I have space to put bass traps there.

I know I ain't gonna get super deep bass due to the small room size. I guess it is gonna be a 'small but perfectly formed' monitor set-up.

Now I am toying with the idea of putting Rockwool into the the corners, but I have read about diaphragmatic traps that can essentially be tuned to cover frequencies.

I want to apply some logic and method to my approach, which in terms of the main wall/floor/ceiling construction I have done thus far. So my questions are as follows:

1. Should I:
a. first set up my equipment with seating, stands and furniture then do. some frequency sweeps via a CD player and chart the characteristics, or
b. set up as above but use some clever software to play via my computer and system to do frequency sweeps and to measure echo and bass decay/reverberation?

2. With the above info:
a. custom build various bass traps/ treatment - if so would various materials help cover the relevant frequency range
b. buy ready made traps/treatment

3. Are subs gonna just cause more problems by overloading a small room with bass
 

Dennis Foley

Member
Sep 11, 2019
11
12
10
71
Los Angeles, CA
www.acousticfields.com
L, Unfortunately, the building insulation material type, amount, and thickness will not address your low-frequency issues at all. It's only sonically viable for low mids and up and it over absorbs at every octave. You can achieve good attack and decay rates for your low-end but you must be willing to treat all surface areas. To treat a small room so that it sounds larger, we have to physically make the room smaller through treatment. Is one of those twists in thinking.
 

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