Author Topic: New Sub Positioning  (Read 1013 times)

Offline vsingh

New Sub Positioning
« on: April 20, 2020, 05:44:15 PM »
Hello ppl,

Managed to get my hands on a BXW10 which completes my 5.1 setup. I need some help to setup please. So my room is rectangular and about 7x4m with my setup on the shorter end. On the left side of my setup i have an open wall which leads into the dining room. If i place the sub on either left or front of the setup, the bass gets lost. I placed the sub in the rear corner and found a perfect spot where i sit that produces amazing low bass. Im happy with this for my spot but if i walk around elsewhere its not that effective. Arent subs supposed to be omni direction? Must i do the sub crawl?

Regards
Vishal

Offline Timber_MG

Re: New Sub Positioning
« Reply #1 on: April 20, 2020, 06:03:26 PM »
For a single sub the alternative is positioning the sub at ear height or close to and crawling a mic to the candidate sub positions. Asymmetric rooms are tough to model and thus hard to suggest positions that might be worth while pursuing.

In short the sub sets up a complex cascade of room modes (standing wave resonances) that cause frequency and position dependant peaks/dips. While positioning won't eliminate these, it can help to address some issues, frequently dramatically.

Can you hookup a PC/laptop and use the setup mic from the receiver with REW?

Offline naughty

Re: New Sub Positioning
« Reply #2 on: April 20, 2020, 06:11:09 PM »
Hello ppl,

Managed to get my hands on a BXW10 which completes my 5.1 setup. I need some help to setup please. So my room is rectangular and about 7x4m with my setup on the shorter end. On the left side of my setup i have an open wall which leads into the dining room. If i place the sub on either left or front of the setup, the bass gets lost. I placed the sub in the rear corner and found a perfect spot where i sit that produces amazing low bass. Im happy with this for my spot but if i walk around elsewhere its not that effective. Arent subs supposed to be omni direction? Must i do the sub crawl?

Regards
Vishal

subs are omni-directional but what you are experiencing is the effects of the room - each room has spots where standing waves occur and these cause nulls in certain spot ie where the frequencies that you need/want are cancelled - so yep you need to keep looking till you find the spot where the bass satisfies your requirements - but better if you optimize the actual seating position

with one sub you cannot even out the room - to create an even output you will need more than one sub which is why some people use multiple subs - even then sometimes all you do is optimise the frequency response curve in specific locations and cannot always optimize the entire room - its not really all that easy ... there are obviously room treatments that can help but sometimes these cost as much as an entire system altogether ie i know people who have spent between R50k to R100k on room treatments only

just work on getting your main seating position sounding how you like it - everyone else can compromise since you pay for the system so you deserve it working to YOUR satisfaction ..... even if you do the "Sub Crawl" and relocate the sub it's gonna take ages of trial and error to find a spot that plays equally as loud all over and its even worse in open plan and large areas - and to call in acoustic experts is only worth it for really expensive and dedicated setups in dedicated rooms IMHO because there won't be an easy or cheap fix for this

Offline vsingh

Re: New Sub Positioning
« Reply #3 on: April 20, 2020, 06:54:46 PM »
subs are omni-directional but what you are experiencing is the effects of the room - each room has spots where standing waves occur and these cause nulls in certain spot ie where the frequencies that you need/want are cancelled - so yep you need to keep looking till you find the spot where the bass satisfies your requirements - but better if you optimize the actual seating position

with one sub you cannot even out the room - to create an even output you will need more than one sub which is why some people use multiple subs - even then sometimes all you do is optimise the frequency response curve in specific locations and cannot always optimize the entire room - its not really all that easy ... there are obviously room treatments that can help but sometimes these cost as much as an entire system altogether ie i know people who have spent between R50k to R100k on room treatments only

just work on getting your main seating position sounding how you like it - everyone else can compromise since you pay for the system so you deserve it working to YOUR satisfaction ..... even if you do the "Sub Crawl" and relocate the sub it's gonna take ages of trial and error to find a spot that plays equally as loud all over and its even worse in open plan and large areas - and to call in acoustic experts is only worth it for really expensive and dedicated setups in dedicated rooms IMHO because there won't be an easy or cheap fix for this
Makes sense. I'm happy with my spot so I think that counts. Thanks

Sent from my VOG-L09 using Tapatalk


Offline vsingh

Re: New Sub Positioning
« Reply #4 on: April 20, 2020, 06:56:30 PM »
For a single sub the alternative is positioning the sub at ear height or close to and crawling a mic to the candidate sub positions. Asymmetric rooms are tough to model and thus hard to suggest positions that might be worth while pursuing.

In short the sub sets up a complex cascade of room modes (standing wave resonances) that cause frequency and position dependant peaks/dips. While positioning won't eliminate these, it can help to address some issues, frequently dramatically.

Can you hookup a PC/laptop and use the setup mic from the receiver with REW?
Thanks for your reply. Keen to explore this anyway. Please can you provide more information on REW.

Sent from my VOG-L09 using Tapatalk


Offline Timber_MG

Re: New Sub Positioning
« Reply #5 on: April 20, 2020, 07:09:03 PM »
Thanks for your reply. Keen to explore this anyway. Please can you provide more information on REW.

You'll find tons of information online for Room EQ Wizard (freeware software too). The measurements help one track the various sub positions and make a more informed choice. It's somewhat useful to overlay left/right channels to look for synergies.

Offline vsingh

Re: New Sub Positioning
« Reply #6 on: April 20, 2020, 08:10:39 PM »
You'll find tons of information online for Room EQ Wizard (freeware software too). The measurements help one track the various sub positions and make a more informed choice. It's somewhat useful to overlay left/right channels to look for synergies.
Great. Will do so. Thanks again

Sent from my VOG-L09 using Tapatalk


Offline naughty

Re: New Sub Positioning
« Reply #7 on: April 20, 2020, 11:02:39 PM »
one thing though ie once you get the hang of it then it will probably be a better move to obtain a proper mic ie the one from the AVR would be okay to give you an idea but IMHO if you seriously want to go this route then maybe something like a UMIK1 would ideally be preferable

https://www.minidsp.com/products/acoustic-measurement/umik-1?gclid=EAIaIQobChMIoZfZ0vL36AIV34BQBh3yEQdQEAAYASAAEgL1LPD_BwE




Offline Timber_MG

Re: New Sub Positioning
« Reply #8 on: April 21, 2020, 09:54:45 AM »
Just be sure to disable all effects on the windows mixer for both the playback and recording device. While an accurate mic is nice to have, for the LF a +/- 2dB tolerance typical of these mics is somewhat dwarfed by the +/- 20dB effects of room modes.So take the very top and bottom of the frequency range of these mics with a bag of salt but it'll still give you a baseline and some experience for a nice lockdown project.

Offline PAPPA3

Re: New Sub Positioning
« Reply #9 on: April 24, 2020, 05:39:54 PM »
For a single sub the alternative is positioning the sub at ear height or close to

Have you tried this?  I.e. have you tried using a sub riser i guess to get it to that height?  Do you do this for finding the best placement for the sub or do you leave it there permanently?

Offline Timber_MG

Re: New Sub Positioning
« Reply #10 on: April 24, 2020, 07:10:40 PM »
Have you tried this?  I.e. have you tried using a sub riser i guess to get it to that height?  Do you do this for finding the best placement for the sub or do you leave it there permanently?

I have done this with a small 4" speaker + EQ (in software after the measurement) on a mic stand and it allowed me to measure a bunch of things really quickly. Even at floor level it'll give one useful insights into evaluating different positions before one starts lugging a subwoofer around.

Edit: read then post: The exercise is to allow the inversion of the sub position with the mic as the mic is much easier to move around. Another name for a frequency response is a transfer function and if you swap mic and sub positions the measurement is theoretically the same. You can place a sub on a couch quite easily, even if the couch changes the response, you're looking at resonances +/- 20dB sometimes.
« Last Edit: April 24, 2020, 07:12:57 PM by Timber_MG »