Should I use 1x15" or 2x12" Genelec subwoofers?

[Mort]

I have a pair of Genelec 8361a that I use with a 15" 7380a subwoofer. I'm happy with the overall response in my small 3mx3m square room.

I have an opportunity (at very modest cost) to switch the 1x15" sub for two 7370a 12" subs. (There is no way to get a second 15".)

Genelec prefers the 7380a 15" sub solution all else equal but they agree I might (emphasis on 'might') get a better bass response. Note that I do not need more SPL or dynamic range, just a better in room response. On the other hand, the subs are large, it's a small room and space is at a premium and my current response is pretty good

Also the only place I can put the two subs are directly behind the mains and against the back wall. This may limit any improvement.

Here is my current all room frequency response with GLM. I can upload mdats if anyone cares to look but I didn't think that's necessary.

Keep one or go for two? I really can't test this ahead of time, I have to make a choice.

Edit: updated with correct Grade report

 

[AudioJester]

Just eyeing that graph, your speakers have a broad room related dip 60-100Hz. GLM and the sub help address this.

Leaving a GLM calibration in the speakers (not sure can you do that with the sub?) - connect as 2.1 to a Dirac ART device. I think that would make a bigger difference, particularly if you also have bass resonances / overhang. Dirac ART also gives you the option of switching to a pair of non-Genelec cheaper subs.

 

[Mort]

Just eyeing that graph, your speakers have a broad room related dip 60-100Hz. GLM and the sub help address this.

Leaving a GLM calibration in the speakers (not sure can you do that with the sub?) - connect as 2.1 to a Dirac ART device. I think that would make a bigger difference, particularly if you also have bass resonances / overhang. Dirac ART also gives you the option of switching to a pair of non-Genelec cheaper subs.

They call you @AudioJester because you are funny!

I know the enthusiasm for DIRAC art is high right now but I'm not switching out GLM and my genelec subwoofers to fix what is most likely an unfixable room mode.

Not that I'm not curious, I would love a Dirac art pre-pro with which to play. Are you running Dirac art right now?

 

[AudioJester]

Yes, I have Dirac ART. Iam a fan boy, it does things no other DSP can in my systems. I have GLM, also have Audiolense, Audyssey, Acourate. Have tried other tools in past including filters designed by Mitcho.

I rate ART >>> GLM. I can get similar results to GLM with other tools, but I cant replicate what ART does with anything.

Got a X3800 and ART license on black friday sales. Currently in my HT 5.4.2 setup.

 

[Mort]

to fix what is most likely an unfixable room mode.

This is the meat of the issue.

Neither Dirac art, nor cardiod, nor anything will erase a serious room null, which I believe I have in my small 3x3M room. Most of us do...

 

[AudioJester]

@Mort I actually think all you need to do is add ART to what you have. Leave GLM callibration in speakers and use analogue inputs to speakers and sub ie 2.1. Are you using a PC as source?

Have a look at ART measurements here and AVS forums. While the biggest difference is bass resonances and smoother frequency response, nulls are being "nullified" with multiple bass sources in ART

 

[Ilkka Rissanen]

I have a pair of Genelec 8361a that I use with a 15" 7380a subwoofer. I'm happy with the overall response in my small 3mx3m square room.

I have an opportunity (at very modest cost) to switch the 1x15" sub for two 7380a 12" subs. (There is no way to get a second 15".)

I do not understand the original question.

7360A is with 10 in woofer
7370A is with 12 in woofer
7380A is with 15 in woofer

Your GRADE report states you have 8341A as main speakers and 7360A as a subwoofer.

 

[Mort]

Your GRADE report states you have 8341A as main speakers and 7360A as a subwoofer.

@Ilkka Rissanen thanks. I have multiple genelec systems and I copied the wrong grade report. I'll update that in a minute.

And yes there was a typo in my original.

I have an opportunity (at very modest cost) to switch the 1x15" sub for two 7380a 12" subs. (There is no way to get a second 15".)

That should read 'two 7370a 12"

 

[KenMasters]

Genelec prefers the 7380a 15" sub solution all else equal but they agree I might (emphasis on 'might') get a better bass response. Note that I do not need more SPL or dynamic range, just a better in room response. On the other hand, the subs are large, it's a small room and space is at a premium and my current response is pretty good

Also the only place I can put the two subs are directly behind the mains and against the back wall. This may limit any improvement.

Measure the uncorrected response of your current sub in the positions available to you and see how they line up. If none offer any improvement above 60Hz, give it a miss, however if otherwise, it might well be worth the trade.

 

[Mort]

1/12 smoothing
Blue is the subwoofer alone in the room, no DSP.
Orange is the summed mains and sub in room, no DSP
Green is my final result with GLM (and a shelf in Wiim)

Measure the uncorrected response of your current sub in the positions available to you and see how they line up. If none offer any improvement above 60Hz, give it a miss, however if otherwise, it might well be worth the trade.

Not much there is there? Here is the Genelec report on my subwoofer.

 

[AudioJester]

Erin recently showed some SBIR simulations regarding this very issue. Cardioid looks like one solution.

 

[Mort]

Unfortunately I don't think cardiod would help below 100hz.

 

[mj30250]

The 60Hz cliff would bother me, that's right in the zone of kick drums and chest punch. If it were me I'd put the sub on furniture sliders and measure the response from all practical positions in the room. If any of those locations filled in the dip, I'd likely swap out the single sub for the two smaller ones.

 

[Mort]

The 60Hz cliff would bother me, that's right in the zone of kick drums and chest punch. If it were me I'd put the sub on furniture sliders and measure the response from all practical positions in the room. If any of those locations filled in the dip, I'd likely swap out the single sub for the two smaller ones.

Yes, the sub crawl is the best method.

I have two challenges with that. The room doesn't allow many positions and the Genelec subs are massive. (15" is 175lbs / 80kg).

In the past when I had smaller subs, I was not able to find a place where I eliminated that hole.

Room sim on REW was not particularly helpful but it's a complex tool. I might need more time with it.

 

[AudioJester]

Meant to ask - is there an audible issue with your current setup?
Looks pretty damn good to me!

 

[Mort]

Meant to ask - is there an audible issue with your current setup?
Looks pretty damn good to me!

Only that suck out at 60-80. It's definitely great quality audio.

 

[GD Fan]

Seems a little risky to me to make the switch. What if the FR curve worsens due to forced placement which sounds somewhat suboptimal?

 

[sonitus mirus]

Only that suck out at 60-80. It's definitely great quality audio.

Honestly, given the constraints, this feels like a lot of effort and risk for a pretty small possible gain.

At the volumes you are listening at, the 7380A is barely breaking a sweat. You are not short on output or headroom, so switching to two 7370As is really only about whether placement differences might smooth things out. And there's the catch.

If both subs have to sit right behind the mains and close to the back wall, they are probably going to light up the room modes in almost exactly the same way. In that situation, two subs behave less like a proper multi sub setup and more like a single source with extra boxes. A deep 60–80 Hz hole that is position related is unlikely to magically fill in.

That dip looks like a room geometry issue rather than a lack of bass energy. DSP is great at taming peaks, but nulls are a different beast.

If you had more freedom to spread the subs out, I would be a lot more tempted by the dual 12 idea. As things stand, the response already looks quite solid overall, and it seems very possible the swap makes things worse rather than better. I would probably stick with the 15.

 

[Mort]

Honestly, given the constraints, this feels like a lot of effort and risk for a pretty small possible gain.

At the volumes you are listening at, the 7380A is barely breaking a sweat. You are not short on output or headroom, so switching to two 7370As is really only about whether placement differences might smooth things out. And there's the catch.

If both subs have to sit right behind the mains and close to the back wall, they are probably going to light up the room modes in almost exactly the same way. In that situation, two subs behave less like a proper multi sub setup and more like a single source with extra boxes. A deep 60–80 Hz hole that is position related is unlikely to magically fill in.

That dip looks like a room geometry issue rather than a lack of bass energy. DSP is great at taming peaks, but nulls are a different beast.

If you had more freedom to spread the subs out, I would be a lot more tempted by the dual 12 idea. As things stand, the response already looks quite solid overall, and it seems very possible the swap makes things worse rather than better. I would probably stick with the 15.

I actually have a little wiggle room with placement. Thing is I have played with both REW room sim and did sub crawls with other subs before I bought the Genelecs. There has never been a configuration without that dip. Mostly it's been worse. But I could place the second sub on the yellow dotted line. Room sim slightly prefers a lower crossover, like 50hz, but it's modest.

Seems a little risky to me to make the switch. What if the FR curve worsens due to forced placement which sounds somewhat suboptimal?

If the 7380a was not on the second floor and did not weigh 170lbs, it would be a lot easier! Genelec subs are ridiculous.

 

[Mort]

I do not understand the original question.

@Ilkka Rissanen A question if you have time. Are you able to confirm that GLM has drawbacks when using different sized subwoofers? What happens if I mix a 7380a and a 7370a in a small room? Genelec support said it was discouraged because they are 'tuned differently'. That never sounded right to me, but I am not an expert.