The Bass Null From Hell - Will A Sub Help?

[days]

I mix in a room that is approximately 12 feet X 14 feet, with 9 foot ceilings. The room has been acoustically treated (6 bass traps, and 4 first-reflection panels), and there has been a lot of testing with various speaker and trap placements to arrive at the current configuration. I use ARC software to correct some of the acoustical issues with the room. Above 160 Hz or so, I have a very good frequency curve, and my mixes translate extremely well at all points above 160 Hz (or thereabouts).


The problem is that once I get below 150 Hz, I start losing the ability to hear what's going on, at first just a little (maybe a 3 dB loss at around 120 Hz), and then very rapidly, so that at around 90-100 Hz, I've lost 6 dB, and at 80 Hz, I've got a null of about 10 dB. As you might guess, I'm not able to hear a lot of what's going on with the kick and bass, and, as a result, I have to rely upon a pair of headphones to help me guess what's happening at the low end - not a good solution.


So, I've reluctantly arrived at the point where I am considering buying a subwoofer, and perhaps upgrading my near-field monitors at the same time. My current monitors (Event 20/20s) are probably the weakest link in my studio at this point. (Although I'm certainly not blaming them for the problem.)


I have these questions:


(1) How much is a subwoofer going to reliably help me (if at all) where I probably need help most, i.e., between 70 and 120 Hz?


(2) Are there any near-field monitors that might do a significantly better job than the Event 20/20s in delivering a better low-end in a small room? (I have tested the Dynaudio BM6As and Focal Solo6s in a pro studio. Both sounded good, but it seemed to me that neither delivered all that much low-end.)


(3) Are there any nearfield/sub combinations you might recommend? (For example: How does the ADAM A7 pair up with ADAM Sub8?)


(Note: These days, I'm mixing mostly acoustic-based indie-type rock, so there isn't lot of sub-50 Hz activity in my mixes.)

[seriousfun]

There is stuff below 50 Hz in your mixes (bass guitar low E string, percussion fundamentals, reverb resonance, etc.) - if your mixes aren't translating without proper representation of this range in your monitors, you do need to address this.

Truely full-range speakers can do this, but can be very expensive, large, and placement will be dictated for high-frequency response, not low-frequency response, and you might not get everything you wish for.

Adding a subwoofer can do just as good of a job, with proper attention paid to placement, crossover slope and frequency, phase/polarity, level, etc.

150 Hz is probably too high for a subwoofer crossover (sounds are typically directional above 100 Hz). You still have reflections in your room that your current bass traps haven't mitigated. That 80 Hz null is probably a sharp 40 dB dip - you need to measure this stuff with at least a 1/12th octave analyzer. Sometimes the addition of a subwoofer will fill in gaps like this even above its crossover frequency (no subwoofer crossover is brickwall), sometimes not.

Beg, borrow, or steal a sub to try.

[Brainchild]

It could be that you do just need reinforcement down low. But it's almost certainly the case that - while your room may be acoustically treated - your room isn't adequately acoustically treated. If you're using ARC, you're skirting actual issues that should be addressed with physical absorption.

[Ethan Winer]

Originally Posted by Brainchild

your room isn't adequately acoustically treated.

This is the correct answer. Six bass traps is a start, but not a total solution in a room that size. For truly excellent results I'd suggest more like 15 to 20 traps. Seriously.

--Ethan

[tINY]

And, a sub can help, but you need 2 or 4 of them...

http://www.harman.com/wp/pdf/multsubs.pdf
http://www.aes.org/tmpFiles/elib/20090129/13680.pdf




-tINY

[days]

Originally Posted by Brainchild

If you're using ARC, you're skirting actual issues that should be addressed with physical absorption.

Without the ARC, my room has a good frequency curve above 200 Hz, and mixes translate well above that point. The ARC makes the curve even better, and brings the usable zone down to around 160 Hz. I know there's a lot of skepticism about the software, but it has made mixing easier for me.

However, the bass null is so huge that ARC can do little to help below 120 Hz or so.

[narcoman]

Originally Posted by Ethan Winer

This is the correct answer. Six bass traps is a start, but not a total solution in a room that size. For truly excellent results I'd suggest more like 15 to 20 traps. Seriously.

--Ethan

Absolutely. 6 is no where near enough. There is a similar sized room at our place which has the equivalent of about 20- 30 of Ethans traps - custom room see.....

[days]

Originally Posted by Ethan Winer

Six bass traps is a start, but not a total solution in a room that size. For truly excellent results I'd suggest more like 15 to 20 traps. Seriously.

--Ethan

15 or 20 traps would pretty much cover the entirety of the wall space in the room. I would be worried that putting that many traps into a 12 X 14 room is going to suck a lot of the high frequencies out of the room - which would be a shame since I'm hearing the higher frequencies really well in my current setup.

[tINY]

If you find the traps making the room dull, you can put peg-board on the front of some of them.

Room correcting EQ can not deal with bass nulls.



-tINY

[Brainchild]

Wow tINY thanks for those links, that is some immensely useful info - especially since I just got my second sub!

[RockManDan]

Originally Posted by tINY

If you find the traps making the room dull, you can put peg-board on the front of some of them.

Room correcting EQ can not deal with bass nulls.



-tINY

+1
-Dan

[Flying_Dutchman]

absorbing energy under 200Hz is critical, you need much depth for the absorbers/ much place, and you need many,

if you want to get 80Hz, you got to be appr. 1 meter from the wall, in theory 0,25x wavelength, heavydistance...

building special resonaters on a given frequency is effective, if you know the frequencies...
to find them, use a mono speker, and send sine waves, when you hear nothing at your listening place, you got the the problem, standing waves,
you got to resonate them out of the air
if you got a +xdb at your listening place, you could use a eq to get it down, but its better to build a resonater, be aware of phase issues with eqs...

[Flying_Dutchman]

Maybe get a JVC BB55LTD, no kidding, i always check the bass on it...

[Dean Roddey]

If you don't have any treatment on the ceiling above you, that could be contributing hugely. It's the shortest axis. As others have said, you'll need more traps than that for such a small room. Also make sure your listening position is correctly placed, about 38% from the end of the room in front of you, long the long axis, and slightly off center left to right, to get out of the worst null from left/right reflections but not so far as to cause an unbalanced room response.

Most of all, don't guess. Get a measument mic and some test software and run the tests and try various trap placements. You never know where the worst problems will be coming from.

And if you want full bass, you'll need something with more than 6" woofers. Adding subs can actually cause even more complications. I think you'd be better off getting a quality set of larger monitors that can carry the low frequency load instead. That's a simpler problem to solve.

[days]

Originally Posted by Dean Roddey

If you don't have any treatment on the ceiling above you, that could be contributing hugely. It's the shortest axis. As others have said, you'll need more traps than that for such a small room. Also make sure your listening position is correctly placed, about 38% from the end of the room in front of you, long the long axis, and slightly off center left to right, to get out of the worst null from left/right reflections but not so far as to cause an unbalanced room response.

Those are the classic suggestions, all of which I followed (except for the number of traps). However, one of the things I did which helped was to actually move my listening position from where it started, at 38% back, to about 42% back.

Originally Posted by Dean Roddey

Most of all, don't guess. Get a measument mic and some test software and run the tests and try various trap placements. You never know where the worst problems will be coming from.

I've done that.

Originally Posted by Dean Roddey

And if you want full bass, you'll need something with more than 6" woofers. Adding subs can actually cause even more complications. I think you'd be better off getting a quality set of larger monitors that can carry the low frequency load instead. That's a simpler problem to solve.

I will certainly consider that approach. Thanks for the advice.

[narcoman]

Originally Posted by days

15 or 20 traps would pretty much cover the entirety of the wall space in the room. I would be worried that putting that many traps into a 12 X 14 room is going to suck a lot of the high frequencies out of the room - which would be a shame since I'm hearing the higher frequencies really well in my current setup.

it won't. You need a lot of bass trapping. Highs come from the speaker directly - you shouldn't be looking to have an acoustically supportive environment in a small room. Just get the speakers , sit in a mix spot (the sweet spot i guess) and control that bottom end.

[dougb415]

Originally Posted by narcoman

it won't. You need a lot of bass trapping. Highs come from the speaker directly - you shouldn't be looking to have an acoustically supportive environment in a small room.

I've been finding this to be true. I had no bass traps at all and just recently a) pulled my speakers away from the wall, b) moved my listening spot to the 38% spot, c) adjusted the speakers to make an equilateral triangle with my chair and d) put a few 2x4' (4" thick) traps at the first reflection points and that has made quite a difference. The sound is now coming more from the speakers, not the walls.

I have more OC703 arriving next week and am going to put some panels on the ceiling as well as adding a couple traps to the back of the room. Then I'll order more OC703 and get some traps in the corners. I'm using Adam A7s and was considering a sub for them but was advised against it by a mastering engineer in Nashville, so it's more traps for me, then we'll see about that sub.

[Ethan Winer]

Originally Posted by days

I would be worried that putting that many traps into a 12 X 14 room is going to suck a lot of the high frequencies out of the room

My company's traps avoid that with a semi-reflective plastic membrane behind the front fabric. I have 45 absorbers in my living room and it is not too dead at all. Except at bass frequencies where you want as much absorption as possible. You can do something similar for DIY traps by adding thin plastic or heavy paper, or even peg board as tINY suggested.

--Ethan