Large or small reinforcement subs?

[YoutubeUniversity]

Summary: So I just built a nice set of HT speakers and need reinforcement subs to even the response. The questions is how much heat do I need on the meat?

Full story: The front stage is anthology towers and a finalist center channel designed by Jim Holtz and Curt Campbell. Rear surrounds are Sopranos by Jeff Bagby. The room is 17x23.
The thing is, with the 2 towers and center channel, that gives me 6 Dayton RS225 mid woofers in the room that already play into the high 20hz range at more than enough volume. The problem is since I currently have seating for 11 in there, the bass response is pretty uneven between seats, mostly around 40-50hz especially. I have acoustic panels and corner bass traps added but obviously the response is going to be slightly uneven since all the bass is coming from the mains. I did some modeling in REW and sticking a pair of subs in the back corners looks like it will flatten everything out.

So if I already have an acceptable amount of bass in the room already and just want to even the response, do I actually need the surface area of a pair of 12s for example or can I get by with even a pair of little 8s. Especially when the main range thats being reinforced is 40+. The room has a mode at 25hz giving a 15db boost if needed so everything is going to extend down pretty well.
BTW the surround is just sitting on there for testing right after I finished it.

 

[Hetfield]

Summary: So I just built a nice set of HT speakers and need reinforcement subs to even the response. The questions is how much heat do I need on the meat?

Full story: The front stage is anthology towers and a finalist center channel designed by Jim Holtz and Curt Campbell. Rear surrounds are Sopranos by Jeff Bagby. The room is 17x23.
The thing is, with the 2 towers and center channel, that gives me 6 Dayton RS225 mid woofers in the room that already play into the high 20hz range at more than enough volume. The problem is since I currently have seating for 11 in there, the bass response is pretty uneven between seats, mostly around 40-50hz especially. I have acoustic panels and corner bass traps added but obviously the response is going to be slightly uneven since all the bass is coming from the mains. I did some modeling in REW and sticking a pair of subs in the back corners looks like it will flatten everything out.

So if I already have an acceptable amount of bass in the room already and just want to even the response, do I actually need the surface area of a pair of 12s for example or can I get by with even a pair of little 8s. Especially when the main range thats being reinforced is 40+. The room has a mode at 25hz giving a 15db boost if needed so everything is going to extend down pretty well.
BTW the surround is just sitting on there for testing right after I finished it.
View attachment 51852

Gorgeous speakers, you built them yourself? Finish is beautiful.

Sent from my Pixel 4 XL using Tapatalk

 

[William Lemmerhirt]

Have you taken any FR measurements? I’d be very interested in seeing them.

The speakers are listed with an f3 of 32hz. So playing meaningful in the high 20’s? Maybe.
For a movie theater experience, you absolutely need subwoofers. While your towers are very nice, there’s no way that they can compete with a sub that plays flat and clean to 20hz or lower. You asked about an 8” subwoofer. There’s not an 8” subwoofer(it hurts even to write that lol) that I can think of that would bolster the low end of your mains in a room that size in any meaningful way. Especially if it’s on concrete.
Imo. A nice pair of 15’s from Rythmik, HSU, monolith, SVS , PSA and the usual ID suspects would do nicely.

 

[Pogre]

What crossover are you using, and yes I agree with Bill. Some fr measurements would shed a lot of light on the situation if you wanna get serious about your bass. Are you using any dsp or room correction?

*Edit: I misread that. No matter how low your speakers play they simply cannot keep up with a subwoofer's performance in deep bass. Bill is spot on. You should be looking at some real subwoofers.

 

[lovinthehd]

8" sub is sort of an oxymoron. I agree with Pogre & Bill.....

Great looking speakers you built, tho!

 

[YoutubeUniversity]

Gorgeous speakers, you built them yourself? Finish is beautiful.

Thanks, yea it took a bit because of different components being backordered and the whole paint process is a nightmare and you eventually just give up on it being perfect and accept little dings and chips. You can't see it unless you are up close.

Have you taken any FR measurements? I’d be very interested in seeing them.

The speakers are listed with an f3 of 32hz. So playing meaningful in the high 20’s? Maybe.
For a movie theater experience, you absolutely need subwoofers. While your towers are very nice, there’s no way that they can compete with a sub that plays flat and clean to 20hz or lower. You asked about an 8” subwoofer. There’s not an 8” subwoofer(it hurts even to write that lol) that I can think of that would bolster the low end of your mains in a room that size in any meaningful way. Especially if it’s on concrete.
Imo. A nice pair of 15’s from Rythmik, HSU, monolith, SVS , PSA and the usual ID suspects would do nicely.

Thanks for the advice so far. I have space behind the rear couches for 2 12's. 15's might be a bit big. It's amazing the budget subs, I can't even DIY one cheaper. I'm not sure if I'd do store bought or DIY. If I did do DIY though I could get a crown amp and then some drivers off parts express. It's hard to know where the drivers offered land vs the various retail subs to know what effective quality I'm building. I don't see a point in making entry level DIY.

As far as EQ:
Everything is run off of an old but nice Pioneer SC-27. So I have octave GEQ down to 63, and 3 band PEQ down to 63 and up to I think 250. Crossover is full range right now. I can set the roll off for each speaker if I add subs though. I think I'd leave the towers full range though to simulate a 4 sub setup.

At the moment the GEQ has:
63hz -2db
250hz +2.5db

The PEQ has:
78hz, Q:2, -6db
149hz, Q:3.4, -4db

I included an average FR from the front and back right couch. The good news is I added a rear set of tri traps to my existing front traps today and it helped a good amount. I used to have a bit of a hole around 300-600 that the traps fixed. It's still there on the back row though but slightly smaller. BTW I've usually run a 10db slope from around 100 down and it's always sounded flat to me so I'm aware it doesnt look pretty but it's kinda naturally doing that anyway. I'm already pulling a huge room mode down at 78hz and shelfing 63 down a bit to try and make it smooth. However the rear row just has a big knee after 60.

Sadly I have no way to target the lower sub range with the setup I have unless I go to separate amps. Then I could use my old 2x4 MiniDSPs I have laying around from my car audio days.

The screen is in the other room right now as I'm about to paint the ceiling black instead of the dark blue which I tried a few weeks ago but I don't like.

 

[Pogre]

A sub or 2 with a proper crossover, some measurements and eq should help with getting that bass response straightened out. Top end looks pretty damned smooth tho. That's a credit to your speakers, which I agree with the guys, look very nice.

DIY with subs isn't necessarily the cheaper route until you get into multiples and use the same power supply. That's when savings really start kicking in. The advantages to using a proper sub or 2 is you have a lot more flexibility with placement and eq options. The room is in charge below a certain frequency (different for every room, but always with bass frequencies) and finding the right sub placement is a big part of taming your bass.