Subwoofer placement with OBs and sealed in subwoofer swarm?

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aceinc

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I built a pair of W style GR Research subs which I have integrated with a pair of Maggies, currently 2.7s. I have the OBs running on the speaker inputs paralleled with the 2.7s. They are dialed in and sound good.

I use the system for both 2 channel and HT. One problem I have with the OBs is when I am watching movies, during loud low SFX content the OBs will occasionally make a loud "cracking" noise which seems out of place for the content. So I have added 3 additional subs in the rear of the room. 1 - 15" sealed Rythmik Audio and 2 - 10" Dayton Titanic IVs in small sealed enclosures, driven by a Crown amp with DSP. I have modified the settings on the OBs so they don't play below ~25hz.

Given a more or less rectangular room 25.75' x 15.5' x 9' with the main listening position ~10' off the back wall what would be a good starting point for the positions of the various woofers be?

Here is a tour of my living room - https://www.youtube.com/watch?v=seXHicRpL-8

Pardon the mess, I have a very understanding wife.

mlundy57

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Re: Subwoofer placement with OBs and sealed in subwoofer swarm?
« Reply #1 on: 16 Jun 2021, 07:57 pm »
I also use my OB speakers/subs for both music and movies. I have the NX-Otica MTM monitors combined with dual servo OB subs for the front end which play for both music and movies, and a sealed 12" servo sub that only plays when there is content of the LFE/sub out channel.

The front subs are set to 14Hz. After having issues with my system, other OB systems I helped set up, and a conversation with Brian at Rythmik, the solution to keep the OB subs from bottoming out on heavy movie low frequency sound effects was to make sure the OB subs never receive the signal from a movie's LFE channel. To accomplish this, the OB subs (1) cannot to connected to an AV pre-pro or AVR's LFE/sub out connection and (2) the bass management in the pre-pro/AVR is not set to redirect LFE content to the front speakers.


How this combination gets hooked up depends on how your amplification is configured. The way you have your front speakers wired up is fine. Make sure the sealed subs are connected to the subwoofer output of your AV processor, the main speakers are set to Large/Full Range, the subwoofer is set to ON, and the subwoofer channel is set to LFE Only with a crossover point of 120Hz. To get the starting settings for the subwoofers, run the Marantz's Audessey program.


Vince in TX

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Re: Subwoofer placement with OBs and sealed in subwoofer swarm?
« Reply #2 on: 16 Jun 2021, 10:54 pm »
I also use my OB speakers/subs for both music and movies. I have the NX-Otica MTM monitors combined with dual servo OB subs for the front end which play for both music and movies, and a sealed 12" servo sub that only plays when there is content of the LFE/sub out channel.

The front subs are set to 14Hz. After having issues with my system, other OB systems I helped set up, and a conversation with Brian at Rythmik, the solution to keep the OB subs from bottoming out on heavy movie low frequency sound effects was to make sure the OB subs never receive the signal from a movie's LFE channel. To accomplish this, the OB subs (1) cannot to connected to an AV pre-pro or AVR's LFE/sub out connection and (2) the bass management in the pre-pro/AVR is not set to redirect LFE content to the front speakers.


How this combination gets hooked up depends on how your amplification is configured. The way you have your front speakers wired up is fine. Make sure the sealed subs are connected to the subwoofer output of your AV processor, the main speakers are set to Large/Full Range, the subwoofer is set to ON, and the subwoofer channel is set to LFE Only with a crossover point of 120Hz. To get the starting settings for the subwoofers, run the Marantz's Audessey program.

Do you have any pictures of how you connected your servo subs?   I ran a pair of RG6 cables specifically to route LFE from my Marantz to my Servo Subs.    :o

aceinc

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Re: Subwoofer placement with OBs and sealed in subwoofer swarm?
« Reply #3 on: 16 Jun 2021, 11:45 pm »
I can get pictures, but I just have the subs and speakers running in parallel. Speaker wire from the power amp to the 2.7 "Yed" to the OB sub.

mlundy57

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Re: Subwoofer placement with OBs and sealed in subwoofer swarm?
« Reply #4 on: 16 Jun 2021, 11:55 pm »
Do you have any pictures of how you connected your servo subs?   I ran a pair of RG6 cables specifically to route LFE from my Marantz to my Servo Subs.    :o

If you are talking about the sealed servo sub, I used an RCA interconnect from the AV processor’s subwoofer output to the servo sub’s RCA input. The model of your AV processor will determine the number of subwoofer outputs you have and, if more than one, whether they can be adjusted independently or not.

I only have one sealed sub in my system so I only use one of the AV processor’s subwoofer outputs.

No pictures though

aceinc

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Re: Subwoofer placement with OBs and sealed in subwoofer swarm?
« Reply #5 on: 17 Jun 2021, 03:02 am »
You really don't get a good shot of the OB subs, but the front edge of the cabinet is ~30" from the front wall and pushed up against the side walls. The reason for this placement is practicality. My 2,7s are just inside each sub toed in slightly.

Is this a good, bad, terrible of meh location for OB subs?

My sealed subs are the two 10" are in the rear corners and the 15" sub is back center M/L.

My question regarding placement is, "If the current locations aren't optimal where should I start?"

mlundy57

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Re: Subwoofer placement with OBs and sealed in subwoofer swarm?
« Reply #6 on: 17 Jun 2021, 03:25 am »
You really don't get a good shot of the OB subs, but the front edge of the cabinet is ~30" from the front wall and pushed up against the side walls. The reason for this placement is practicality. My 2,7s are just inside each sub toed in slightly.

Is this a good, bad, terrible of meh location for OB subs?

My sealed subs are the two 10" are in the rear corners and the 15" sub is back center M/L.

My question regarding placement is, "If the current locations aren't optimal where should I start?"

A good method to determine placement is called a "sub crawl". Start with one of the sealed subs, turn the other two off. Put the sub you are working with in the listening position and play something with a good repeating base line through it. Get down on your hands and knees and crawl around the room listening for where the bass sounds good. Mark that spot with a piece of tape. Continue crawling, listening and taping until you have identified the location with the best bass response. This is where you want to place the sub. If that spot is not workable, use the next best spot. If that's still not practical, use the spot with the best response that is possible.

Now put the second sub in the listening position and, with the first sub also playing, repeat the process. rinse and repeat for the third sub. If you are going to have multiple listening positions, use a different position for the second and third sub if required.

In general, the closer a sub is to a boundry, the more output it will have. The more boundries, the more output so a corner gives the most, and possibly too much. Sometimes room usage and furniture placement limit the possible positions.

In my living room, I placed the sealed sub directly behind the couch which has it 3ft away from the closest wall, 6ft away from the wall behind it, 15ft away from the other side wall and 12ft away from the front wall. It works very well in this location. In the upstairs room with the OB speakers the sealed sub is next to the single listening position which is the only place it can go. May not be the optimal spot for bass performance but works well enough and doubles as a side table.

lokie

Re: Subwoofer placement with OBs and sealed in subwoofer swarm?
« Reply #7 on: 17 Jun 2021, 02:20 pm »
Re. Sub Crawl: I'm about to do the sub crawl and was wondering what was the best way to acclimate the sub. i was thinking of removing my sitting position chair and pointing straight up and maybe elevating off the floor somehow. Any advice here? Also... what about taking in consideration of other sitting positions? I am thinking just do the same thing and try to find the common "best' results??

Re. Swarm strategy: I am hoping Danny will jump in here regarding the strategy to place a couple of subs behind the listening position with "out of phase subs". Question: Would the placement of the "rear out of phase subs" be the same as the "sub crawl" ,method or is this something completely different?

I am contemplating infinite baffle rear subs due to my listening room being our living room and IB's would provide for a more optimal placement (maybe depending on studs etc.) and the fact that they can be invisible. But, once implemented, they will be unmovable.

Vince in TX

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Re: Subwoofer placement with OBs and sealed in subwoofer swarm?
« Reply #8 on: 17 Jun 2021, 04:25 pm »
If you are talking about the sealed servo sub, I used an RCA interconnect from the AV processor’s subwoofer output to the servo sub’s RCA input. The model of your AV processor will determine the number of subwoofer outputs you have and, if more than one, whether they can be adjusted independently or not.

I only have one sealed sub in my system so I only use one of the AV processor’s subwoofer outputs.

No pictures though

Mine are actually the Servo Sub 4 kits, so they are open baffle.   I have a Marantz SR6012, which has two outputs that I believe can be controlled independently, although currently it only has one ported sub attached to it.   I'm also struggling with sub placement.   I chose both drivers facing forward, so I hope that would allow me to have them closer to the front wall.   We shall see.




mlundy57

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Re: Subwoofer placement with OBs and sealed in subwoofer swarm?
« Reply #9 on: 17 Jun 2021, 08:16 pm »
Mine are actually the Servo Sub 4 kits, so they are open baffle.   I have a Marantz SR6012, which has two outputs that I believe can be controlled independently, although currently it only has one ported sub attached to it.   I'm also struggling with sub placement.   I chose both drivers facing forward, so I hope that would allow me to have them closer to the front wall.   We shall see.




I also have the servo sub kit 4 and, until getting an ARCAM AV40 pre-pro, had them connected to a Marantz SR7008 for movies. If you want to avoid bottoming issues with the OB subs, do not connect them to either of the Marantz's subwoofer outputs. These outputs carry the LFE channel that can cause the problem during heavy low frequency effects like a star destroyer flying over.

Instead connect the OB subs to the Marantz's Left and Right main speaker outputs. You can do this either by connecting two pairs of speaker cables to the Left and Right Main speaker binding posts then connecting one pair of speaker wires to your main speakers and the second pair of speaker wires to the High (speaker) level inputs of the A370 subwoofer amp. The second way is connect one pair of speaker wires to the Matantz's Left and Right main spekaer binding posts and to your main speakers then connect a pair of RCA interconnects to the Matantz's Left and Right main speaker pre-outs and to the A370 sub amp's line (low) level RCA inputs.

For the LFE content in movies, connect one or two Servo Sub kit 2 to the Matantz's subwoofer output(s). The servo sub kit 2 is designed to handle those low level infasonic frequencies in the LFE channel. My servo sub kit 2 subwoofers easily handle frequencies down to 10Hz at high enough levels to vibrate the couch and rattle pictures on the walls.

With this type of configuration, OB subs on the Left and Right main channels and a sealed servo sub or two on the subwoofer channels, each subwoofer handles the frequencies and situations it was designed to handle. You get the best sound quality and bass response with no chance of damaging any speakers.


Vince in TX

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Re: Subwoofer placement with OBs and sealed in subwoofer swarm?
« Reply #10 on: 17 Jun 2021, 10:24 pm »
I also have the servo sub kit 4 and, until getting an ARCAM AV40 pre-pro, had them connected to a Marantz SR7008 for movies. If you want to avoid bottoming issues with the OB subs, do not connect them to either of the Marantz's subwoofer outputs. These outputs carry the LFE channel that can cause the problem during heavy low frequency effects like a star destroyer flying over.

Instead connect the OB subs to the Marantz's Left and Right main speaker outputs. You can do this either by connecting two pairs of speaker cables to the Left and Right Main speaker binding posts then connecting one pair of speaker wires to your main speakers and the second pair of speaker wires to the High (speaker) level inputs of the A370 subwoofer amp. The second way is connect one pair of speaker wires to the Matantz's Left and Right main spekaer binding posts and to your main speakers then connect a pair of RCA interconnects to the Matantz's Left and Right main speaker pre-outs and to the A370 sub amp's line (low) level RCA inputs.

For the LFE content in movies, connect one or two Servo Sub kit 2 to the Matantz's subwoofer output(s). The servo sub kit 2 is designed to handle those low level infasonic frequencies in the LFE channel. My servo sub kit 2 subwoofers easily handle frequencies down to 10Hz at high enough levels to vibrate the couch and rattle pictures on the walls.

With this type of configuration, OB subs on the Left and Right main channels and a sealed servo sub or two on the subwoofer channels, each subwoofer handles the frequencies and situations it was designed to handle. You get the best sound quality and bass response with no chance of damaging any speakers.

Good stuff.   Coincidentally, I did run two pairs of wires for each of the front L/R speakers in the event I ever wanted to bi-amp (which the X-Static doesn't support).   It's only 18g wire, though, so in talking with Klaus (Odyssey) who is building my Kismet 3-channel, I was planning to bind them together into single L/R cables.   The 25' run might otherwise be too much for 18g.   In retrospect, I should have ran 16g.   So I may try the latter of your two suggestions and run that RG6 cable from the pre-amp RCA output to the RCA low on the A370.   Then I'll place my SVS PB-2000 at the back of the room to handle LFE until I can get time (and funds) together for some Servo Sub 2 kits.   I think with the bass shakers in the seats and the PB-2000, there will be plenty of shake on that wood floor.    :thumb:

Vince in TX

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Re: Subwoofer placement with OBs and sealed in subwoofer swarm?
« Reply #11 on: 17 Jun 2021, 10:26 pm »
Incidentally, apologies, @aceinc.   I didn't mean to hijkack your thread.   It just seemed we are dealing with a similar setup, and I'm glad you posted because I was about to make the same mistake and hook LFE to my OB subs.   :duh:

aceinc

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Re: Subwoofer placement with OBs and sealed in subwoofer swarm?
« Reply #12 on: 18 Jun 2021, 01:15 am »
Incidentally, apologies, @aceinc.   I didn't mean to hijkack your thread.   It just seemed we are dealing with a similar setup, and I'm glad you posted because I was about to make the same mistake and hook LFE to my OB subs.   :duh:
I've been hijacked before, and have done a bit of hijacking myself.

Back to the regularly scheduled program;

I would be interested in comments on my sub placement as defined above.

mlundy57

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Re: Subwoofer placement with OBs and sealed in subwoofer swarm?
« Reply #13 on: 18 Jun 2021, 03:18 am »
I've been hijacked before, and have done a bit of hijacking myself.

Back to the regularly scheduled program;

I would be interested in comments on my sub placement as defined above.

That's a pretty good starting point. OB subs can be placed close to side walls since they have nulls at 90 degrees.

Take some measurements at your different listening positions and see how the bass looks. REW is a good free program for doing this. You will also need a USB mic like the MiniDSP Umik 1, a microphone stand, and a computer that can be connected to your stereo system to make the measurements.

You can put the mic in each of your listening positions and run sweeps to see if the bass is even or has big spikes and/or dips. Based on the measurements you can move your subs around until you get the bass response you want.