Placing a second sub

[nitpicker1]

I'm researching how to place my second sub and was wondering your opinion about these guides being applied loosely in home theatre as well?

https://www.lynxproaudio.com/lx-resources/uploads/2016/05/Lynx-Pro-Audio-Expert-Guide-Positioning-Subwoofers.pdf

https://www.diva-portal.org/smash/get/diva2:1020371/FULLTEXT02

I figure they must apply in some way, it's all sound in confined spaces. But professional DJ audio all seem to point towards keeping subs together for best spread and minimum cancellation. While on YT and forums I find home HiFi people insisting on having them far apart.

Reason I'm getting another, is I was playing random 30-100hz specific test tones via DD toolbox app one day while walking around listening area and I noticed a very low ~50hz dip in one seating area, while strong in another. Incidentally the single sub I have now, stands to the left of the center, inside the tower, and that entire side of the room was strong in all tests I did. The dip happens right in front a the other side of the TV stand/table, where I'm thinking the second sub is going to stand (a typical newbie front stage... I know). Since it's almost near field, I'm hoping it could work out. DJ audio calculations in the lynx link above suggests them being no more than 2.26 meters apart if 100Hz crossover, center to center. Mine would be 1.6 meters.

I know buying $100 mic = "this is the way..." and look at graphs all day until I dream about them, I'm just hesitant because of budget... And it would just be parked in a box after being done with it or sell it again. Wanting to go by ear, if I can. I have a very low budget but trying my best to cover OK sound since I spend a lot of time on movies and tv shows. I love the immersive effect it has. The subs are cheap 180W RMS/250W MAX 12" things, but even just a single made a world of difference than just the single 10" side-firing woofers in my towers. Now I'm just looking to roughly even out response. WAF factor is strong, so front wall only.

Then there's this Audioholics YT vid that suggests further apart again.

I have no choice other than going by ear and getting inspiration from guidelines and experience for now.

 

[Purité Audio]

REW’s ‘room simulation’ you can virtually re-create your room including two subs and then virtually drag everything around.
Keith

 

[Elkerton]

Welti and Devalier's research of multiple subs in a square room (worse case) recommends the placement of 2 subs in a room at mid points on opposite walls for the best Mean Spacial Variance (MSV), that is the evenest bass over a large area in the room. The downside is a reduction of Mean Output Level (MOL), which means the subs have to be played louder. This has worked Very well in my own listening room. Read section 4 paragraph 3 for the conclusions if the whole paper is too much:

https://audioroundtable.com/misc/Welti_Multisub.pdf

 

[privilege15]

Trial and error. Disregard the smart articles and go by REW measurements, your personal experience and you will find the best location that works best in YOUR room. Don't hesitate to try placing the subs even behind your main listening position (MLP). And since you have two subs, try to keep them symmetrical against your ears. For example, if you place one sub on the right side of your room, put the second one on left at the same distance relative to the other one and your ears. If you are experimenting and placing one sub at the front and one behind the MLP also keep them symmetrical and dead centre between your ears.

While you won't be able to determine the direction of the sound source, you will feel the pressure on your ear drums that the subs generate and if you happen to place them unevenly relative to your MLP, you will feel more pressure from the closest sub and the direction it is positioned from and less from the one further away. Try to keep them symmetrical at all times if possible.

 

[nitpicker1]

Thanks for input, it helps.

I find myself browsing microphones even if I weren't planning on it, as I think there will always be a question mark in my head unless I see actual results...

I don't know anything about quality or mics... But UMIK-1 and UMM-6 seem to be popping up a lot... Are they the minimum I should go for?

 

[staticV3]

I don't know anything about quality or mics... But UMIK-1 and UMM-6 seem to be popping up a lot... Are they the minimum I should go for?

The UMIK-1 is great.

If you have a known good 3.5mm microphone input device, then you can save some money with a Primo EM257, see here:

Could use some 101 advice

Hello, First of all I‘d like to say I’m super impressed with the wealth of exact information and knowledge available here. I had a homestudio once but started traveling about five years ago and haven’t done anything with recording music since. It is now that I’ve temporarily settled in a place...

www.audiosciencereview.com

Here's one shop which sells the EM258:

Primo EM258 Mono module, with 3.5mm plug, 1.5m

A tiny (6 mm dia) high quality Primo EM258 capsule, wired as a complete working microphone module, ready to build into a housing or enclosure.Requires capsule and cable to be supported. These rubber holders fit the capsule: Primo 6mm holder and 6 mm Microphone Holder Good ultrasonic responseCan...

micbooster.com

Lastly, check out Multi Sub Optimizer.

 

[DVDdoug]

I don't know anything about quality or mics... But UMIK-1 and UMM-6 seem to be popping up a lot... Are they the minimum I should go for?

Any calibrated measurement mic is fine. They aren't "flat" but they come with a calibration file to make them measure flat (with REW, etc.).

USB calibration mics are also calibrated for SPL. With an analog mic that depends on the gain of the preamp so you have to do your own SPL calibration (with an SPL meter) or ignore it if you're only measuring frequency response.

Of course it is best to experiment and measure. But Toole has a recommendation of both subs on the same wall, 25% of the room-width from the side-walls. (He doesn't say this is always the best setup.)

)

 

[sigbergaudio]

Trial and error. Disregard the smart articles and go by REW measurements, your personal experience and you will find the best location that works best in YOUR room. Don't hesitate to try placing the subs even behind your main listening position (MLP). And since you have two subs, try to keep them symmetrical against your ears. For example, if you place one sub on the right side of your room, put the second one on left at the same distance relative to the other one and your ears. If you are experimenting and placing one sub at the front and one behind the MLP also keep them symmetrical and dead centre between your ears.

While you won't be able to determine the direction of the sound source, you will feel the pressure on your ear drums that the subs generate and if you happen to place them unevenly relative to your MLP, you will feel more pressure from the closest sub and the direction it is positioned from and less from the one further away. Try to keep them symmetrical at all times if possible.

If the goal is as even frequency response as possible, symmetric placement isn't necessarily the best approach.

 

[nitpicker1]

I decided to just close my eyes and pull the trigger on the UMIK-1, figured I might as well just save time and stop overthink it...


Another thing I was wondering... Now that I'll have a mic. I've always wanted to try and make a speaker on my own. I figured this mic may become a good tool for that.

In this video he explains using wool in the top of his speaker to make sound move slower to get a better "decorrespondance of frequency peaks", does he generally mean the hunt for a flat frequency response? Slight warning: He has a test tone going at the same time, which may be annoying

 

[ozzy9832001]

For my room, the best placement for the 2 subs was one between the speakers and the other on the right sidewall about half way.

 

[nitpicker1]

Did lots of learning and measuring today. Ended up with both within speakers, worked out surprisingly well, a small dip towards the crossover point, but nothing that bothered me. With the single sub before placing the second sub, I noticed 76Hz was entirely gone - while around 35Hz was boosted with 10dB in one of the main seats. I tried to put them together further along the wall so they centered in the room, but that measured worse than within speakers each side of TV.

After placement, I managed to get a much better dB level across the listening area. With 1 sub it varied ~10dB across the listening area. It's much more even now. I also quickly realized it could help me set a proper level on all speakers, been using smartphone until now, which I realized had been about 10dB off target, even for normal speakers...

May play around with other placements later, like rear, but need longer RCA's first. Could research wireless, but I prefer to wire when I can..

Happy for now, glad I bought both a second sub and a measuring mic.