Do two subs rated for medium room size combine to be rated for large room

[chuck ciali]

I have a large open family room approximately 14'x32'x8' that opens onto a kitchen and sun room. I am looking to replace an NHT Sub one subwoofer. I am wondering if getting two subs like the RSL Speedwoofer 10S will perform as well as a single larger sub like the HSU ULS-15 mk? I do a mix of audio listening and movie watching.

Thanks
Chuck

 

[William Lemmerhirt]

Hi chuck. IMO the answer is, kind of. Lol. As far as output is concerned, yes you can add multiple subs and gain output and headroom. However, a subwoofer can only play as low as it can play. So even if you have 10 subs that roll off at 25hz, they’ll never have meaningful output at 20hz.
I always recommend buying the single best sub you can, and then immediately start saving for a second one if needed. Others might say having multiples is more important, but if you only care about one seat in particular, careful placement and setup can give great results with a single. Also, I really enjoy subs with deep extension, so that’s why I’ve formed opinion in that way. I’ve done subs in a few different ways, and for my money, the single best one you can get with a second soon after suits my logic system. Especially if you listen at same volumes, a great single can be, well, great!

 

[everettT]

More subs are more even sound. If they are colocated then you get an increase in SPL. But that dosent ever make up the ability to pressurize a room .

 

[Drunkpenguin]

I saw in increase with duals, but its not double like you would think. I would guestimate a few percentage points maybe. One big sub is usually plenty for most people. Multiple subs can smooth out response and help when you have multiple rows of seats to address, but I would say if you have to choose go for 1 big one.

 

[ryanosaur]

Thought I have seen it mentioned to be a +3-4dB increase in output, per additional sub, real world usage.

 

[ryanosaur]

I like William's approach. I've been using an old HTIB in a very large room >8000'3. Though not earth shattering, room adjusted, crawled out... it has performed admirably. Had I upgraded to a single VTFU15HMk2, I would have experienced significant greater performance. Two would be ideal.
Instead, I ended up in my 2000'3 room, and am waiting on two Ultra X13s. Probably overkill, but the price was right! In my smaller room, not looking for output so much as good extension and complete audio immersion (perhaps, sub-mersion? (hope I don't drown!)). I digress:
If you go sealed, look at Rythmiks 15" subs. One would get you started for certain. Two would be great, and you'll get better extension I think than any other sealed sub. The ULS15s are supposed to be beasts, and very affordable, but the extension is only going to possibly come from room gain (which I think is minimized in larger rooms like yours). That said, the VTF15Hmk2, Outlaws, and Monoliths are all very highly recommended too! If you're not aiming for deepest extension, you could also look at the other ported Hsus... VTF3 or 2, especially doubled, should handle your space pretty respectably.

 

[everettT]

Thought I have seen it mentioned to be a +3-4dB increase in output, per additional sub, real world usage.

A slight bit, but they would have to be colocated to increase them noticeably, and then ....

 

[William Lemmerhirt]

Thought I have seen it mentioned to be a +3-4dB increase in output, per additional sub, real world usage.

This is a pretty good rule of thumb but don’t forget about the room size/shape and placement of subs and LP. In my room(large) all 3 of my subs are set at about 72db individually, but are at 78-80db collectively, so yeah, I get 3-4 extra per sub. They are not co-located, but rather one in each of 3 corners. Hopefully a fourth someday.

 

[William Lemmerhirt]

A slight bit, but they would have to be colocated to increase them noticeably, and then ....

Actually I’ve found the opposite in my room. My subs(3) are not coloacated and when running the test tone starting with one, and adding the other two, I get 3-4db with each one.

 

[William Lemmerhirt]

I saw in increase with duals, but its not double like you would think. I would guestimate a few percentage points maybe. One big sub is usually plenty for most people. Multiple subs can smooth out response and help when you have multiple rows of seats to address, but I would say if you have to choose go for 1 big one.

I agree. One great one vs two not great ones. Of course everyone’s mileage is different, and not everyone agrees with me. But...
Usually you can expect about 3db for a second sub. Also, iirc each boundary adds about 3db. So for “X” amount of subwoofer output in free air, when you bring it in a house, there’s automatically cabin gain. So theoretically when you place a subwoofer on a sidewalk and then move it to a corner, you should see 3db increase just for the extra boundary. Obviously that’s an oversimplification not accounting for modes etc.

 

[everettT]

Actually I’ve found the opposite in my room. My subs(3) are not coloacated and when running the test tone starting with one, and adding the other two, I get 3-4db with each one.

You need a 6db increase to have a noticeable effect on output. I can see getting 3db, but thats just the second sub not both.

 

[TLS Guy]

I have a large open family room approximately 14'x32'x8' that opens onto a kitchen and sun room. I am looking to replace an NHT Sub one subwoofer. I am wondering if getting two subs like the RSL Speedwoofer 10S will perform as well as a single larger sub like the HSU ULS-15 mk? I do a mix of audio listening and movie watching.

Thanks
Chuck

If the subs are spaced you will gain 3db, if they are side by side you will gain 6 db.

 

[lovinthehd]

Isn't it actually if they're within 1/4 wavelength of each other for acoustic coupling?

 

[shadyJ]

If you double the amount of subs in one room, you double the headroom because you have doubled the acoustic energy being dumped into the room. You may not actually measure a precise 6 dB increase at every frequency, and if there are phase conflicts you might even lose SPL at some frequencies, but at other frequencies you could easily see more than a 6 dB gain. If you do want to see a 6 dB gain at every frequency you need to place the sub next to each other, but if you do that, it does nothing to address the room modes.

 

[chuck ciali]

All:

Thanks for the detailed feedback and recommendations... and quick turn around. My take away is as William recommended first "buying the single best sub you can, and then immediately start saving for a second one".

Now to decide on which one!

-chuck

 

[ryanosaur]

Now to decide on which one!

Having spent a lot of time looking, researching and asking questions, myself: you are in the right place!

I just chose Outlaw Ultra X-13. For me it was the sale price that tipped me here.

Next on my list was Rythmik: check out the 15" variety for your room. You could go sealed or ported with them depending on the quality of sound you are after.

Hsu is probably the value leader in terms of performance vs cost, and should be considered very strongly.

The Monolith subs from Monoprice are quickly becoming favorites for their performance.

And last but not least: SVS. You should probably look at their 4000 series for your room. The new 3000 series will probably work fine, as well.

Most of these are reviewed here on Audioholics, too!

Happy hunting!

 

[Danzilla31]

Having spent a lot of time looking, researching and asking questions, myself: you are in the right place!

I just chose Outlaw Ultra X-13. For me it was the sale price that tipped me here.

Next on my list was Rythmik: check out the 15" variety for your room. You could go sealed or ported with them depending on the quality of sound you are after.

Hsu is probably the value leader in terms of performance vs cost, and should be considered very strongly.

The Monolith subs from Monoprice are quickly becoming favorites for their performance.

And last but not least: SVS. You should probably look at their 4000 series for your room. The new 3000 series will probably work fine, as well.

Most of these are reviewed here on Audioholics, too!

Happy hunting!

Hey how are those subs working out for you have you them in yet? How do they sound?

 

[ryanosaur]

Hey how are those subs working out for you have you them in yet? How do they sound?

I’m on the slow boat, amigo! My receiver is still at warranty service, and I think Outlaw only just today is going to process my order! I’m also confirming my order for the philharmonics today! I might not see the subs for two more mondays, and the BMRs could run a little longer since he’s waiting on an order of Raals. I’ll share when I’m all in, though. But the big one is going to be about 5 mos out! When the 3’s should be ready!

 

[ryanosaur]

@Danzilla31, Just got my official invoice from Outlaw! No tracking number yet, but they're only shipping from Oregon to Sonoma County. I should have them next week! *fingers crossed

Now about that AVR... the tech said maybe two more weeks for the part to come in. any delays, and my x-13's will have a fine patina of dust before I even get to hook them up!

 

[Danzilla31]

@Danzilla31, Just got my official invoice from Outlaw! No tracking number yet, but they're only shipping from Oregon to Sonoma County. I should have them next week! *fingers crossed

Now about that AVR... the tech said maybe two more weeks for the part to come in. any delays, and my x-13's will have a fine patina of dust before I even get to hook them up!

At least they'll be 2 pretty looking pieces of audio heaven with a fine patina of dust on them!