I am intending to install 2 identical large subs into my music system (no HT). The listening room is 6.4m x 6.7m x 2.4m and well damped with carpet, books, LPs as well as soft furnishings. The subs are forward firing 2x10" in 90 L sealed enclosures. MiniDSP crossover is used.
My question is, where is a good position for the subs? If it was a single mono sub, I would be putting the sub front centre at the wall/floor join. The conventional wisdom is that it is impossible to positionally locate sub frequencies, but I suspect that is not the full story. Will stereo subs contribute to the stereo image? Even though acoustic instruments tend to have nothing much below 40 Hz, electronica can be pretty extreme at low frequencies.
My question is, where is a good position for the subs? If it was a single mono sub, I would be putting the sub front centre at the wall/floor join. The conventional wisdom is that it is impossible to positionally locate sub frequencies, but I suspect that is not the full story. Will stereo subs contribute to the stereo image? Even though acoustic instruments tend to have nothing much below 40 Hz, electronica can be pretty extreme at low frequencies.
The important thing to know is that lf subs have no directivity. The wavelength is so large that for all intends and purposes they spread all around, 360 degrees.
So pointing a sub is useless, you can turn it any which way and that does not change the sound.
Another result of the long wavelength (long with respect of the room dimensions) is that depending on those dimensions, you will get standing waves in the room. That means that at some point you will have strong bass, at another point a few feet away it can be almost zero.
Again, depending on room size and shape, it may be advantageous to place subs at some non-symmetrical position.
A good way to figure is out is to put the sub in your listening position. Play some bass-heavy music and walk around the room until you find a spot where the bass is the way you like it. That then is the place to put your sub.
You can repeat it for the 2nd sub for finetuning or to widen the sweet listening spot.
You can even do better with more subs; up to four would let you have very good bass reproduction anywhere in a room.
Jan
So pointing a sub is useless, you can turn it any which way and that does not change the sound.
Another result of the long wavelength (long with respect of the room dimensions) is that depending on those dimensions, you will get standing waves in the room. That means that at some point you will have strong bass, at another point a few feet away it can be almost zero.
Again, depending on room size and shape, it may be advantageous to place subs at some non-symmetrical position.
A good way to figure is out is to put the sub in your listening position. Play some bass-heavy music and walk around the room until you find a spot where the bass is the way you like it. That then is the place to put your sub.
You can repeat it for the 2nd sub for finetuning or to widen the sweet listening spot.
You can even do better with more subs; up to four would let you have very good bass reproduction anywhere in a room.
Jan
Great advice there, positioning is everything. I prefer white noise for that test, with sub only playing as it's much quicker to find the better spots, then turn on the mains and crawl around again. Make sure your head is always down where the subs will be. If you have a measurement mic (umik) and REW software, measurements with the subs in positions are extremely helpful after the likely possible positions are identified with the first test.
A systematic method is given in a white paper by earl Geddes that can be found here:
Serious Audio: Two Great Articles on Multiple Subwoofers by Dr. Earl Geddes
A systematic method is given in a white paper by earl Geddes that can be found here:
Serious Audio: Two Great Articles on Multiple Subwoofers by Dr. Earl Geddes
Lots of valuable tips so far. Thanks people.
Does running the subs with separate left and right signals have any benefit or is mono bass L+R to be preferred? I assume if there is any stereo information at sub frequencies (below 80 Hz) that a symmetrical arrangement is better. I expect LP low bass to be mono but maybe digital files will not be so constrained.
Good advice here, particularly with Jan and cowan audio participating.
Toole, Devantier et al particularly looked at 2 subs in symmetric locations in at least 1 paper that I recall:
https://www.harman.com/sites/default/files/multsubs_0.pdf
Geddes is a proponent of asymmetric placement but a minimum of 3 subs which is particularly effective in many rooms since the rooms are not perfectly enclosed boundaries. I use Geddes' method to excellent effect.
See here for a more thorough explanation of the vagaries of asymmetric and symmetric placements of multiple subs:
Tuning multiple subs
Read the Bass Integration Guide parts 1-3 by one of your own Aussies, Paul Spencer!:
Bass Integration Guide
And it goes without saying that measurements are the only way to do it right. You need to get really, really good at it. It should be repeatable and easy.
Recently, I had to integrate 4 subs, it took me 6 hrs/day and 3 days. I didn't listen to music at all during that time until the integration was perfect!
Best,
Anand.
Toole, Devantier et al particularly looked at 2 subs in symmetric locations in at least 1 paper that I recall:
https://www.harman.com/sites/default/files/multsubs_0.pdf
Geddes is a proponent of asymmetric placement but a minimum of 3 subs which is particularly effective in many rooms since the rooms are not perfectly enclosed boundaries. I use Geddes' method to excellent effect.
See here for a more thorough explanation of the vagaries of asymmetric and symmetric placements of multiple subs:
Tuning multiple subs
Read the Bass Integration Guide parts 1-3 by one of your own Aussies, Paul Spencer!:
Bass Integration Guide
And it goes without saying that measurements are the only way to do it right. You need to get really, really good at it. It should be repeatable and easy.
Recently, I had to integrate 4 subs, it took me 6 hrs/day and 3 days. I didn't listen to music at all during that time until the integration was perfect!
Best,
Anand.
Last edited:
One way to deal with that is a very thick (minimum 4 inches) absorber, and/or a sub placed in that location, typically with the phase flipped to 'eliminate' the back wall.I hope you aren't sitting anywhere near the back wallTry not to boost a dip too much
Of course, all of this should be done and corroborated with measurements.
Besides the low frequency region, I have found that treating the back wall (particularly when it is closer to the MLP, ie 8 feet or less), eliminates a back wall reflection, contributing to better staging from a subjective standpoint. It's a reflection point indeed in some rooms.
But I am probably in the minority of those who find it fun to do these experiments especially when science explains it
REW has a nice modeling/room simulator to play around with this stuff.
Best,
Anand.
Last edited:
A Double Bass Array would be my fantasy. Thankfully I only need it to sound right in one spot. I have two dipole subs, which effectively means four
A Double Bass Array would be my fantasy. Thankfully I only need it to sound right in one spot. I have two dipole subs, which effectively means four
Indeed, DBA's are cool but cannot be thought of in a retrofit design. If you are designing an audio or HT room from the ground up, the DBA is an option.
I have done the two dipole sub thing and the 2 dipole and 2 monopole subs thing.
In the end, 4 monopole subs, properly designed of high sensitivity and asymmetric distribution around the room, along with measurements was the ticket.
Many paths to nirvana...
Best,
Anand.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.