Can subwoofers be too large for a room? Output, rather than physical size.

Harkon321

Well-known Member
My new room is 3.8m x 3.5 x 2.3m. Dedicated room, sealed, literally seating and an AV cab in the room. Plan is two subwoofers, loads of placement options.

I've bought a huge amount of my equipment as ex demo or second hand for the new room. Currently all boxed ready to fit - MK IW150, MKIW95s, MKIW85s.

It's not a big room so shouldn't be hard to pressurize, but how big is big enough? I imagine at some point, if you're running a pair of huge PSA 18" subs or the pair of SVS PC4000s (that I've just been looking at in the classifieds), that you are only running them at a small amount of their potential. Loads of headroom (no distortion), but will it ever be used?

In my current living room set up (similar size) I've run Dali E12-F, Monolith+ and, currently, a MK V12. The MK V12 I've got in there at the moment is a capable sub, really good for music. The EQ needs redoing on since I've moved it, but it doesn't scare me. That's what I'm after... The explosion, or gunshot, or score that pins you to your seat.
But how big do you go to achieve that.... I'm guessing a pair of SVS PC4000 would certainly do it, but do I need to go that big? Is a pair of ported subs that big going to be a nightmare to EQ... I had planned on going sealed given the room dimensions.
 

rccarguy2

Well-known Member
I'd say a single pc4000 will be plenty in that room. In fact I'd probably would go dual sb3000 instead.

I have a single sbu13 which is basically the sb version of the 4000 in a room double your length and .5m higher ceiling and it copes ok, although I am closer to the limits relative, say about 90% of max. That's with sub running 3db hot and only in certain movies, aquaman had a lot of low end during tsunami scene. It hasn't bottomed out but can tell when doesn't have much headroom left.
 
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Ultrasonic

Well-known Member
How much is too much will depend on how loud and how low you want to go.

As single PSA S1512 may well be all you need, let alone a pair of 18" subs.

Do you have a microphone to have any idea what you're achieving with your current subs and if you're reaching their limits or not?
 
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rccarguy2

Well-known Member
Yeah you want headroom and better quality sub sounds better, goes power etc but if you fit two jtr rs2 in a small room and you have 40db of head room whats the point?

Like buying a HGV just to do your weekly shopping
 

willz

Active Member
Personal pref I guess, I'd happily but 4 18" subs in this 11 x 17ft room if the neighbors wouldn't call the police and by budget allowed.
 

Ultrasonic

Well-known Member
Is a pair of ported subs that big going to be a nightmare to EQ...

Just to add that I don't see any reason that bigger, more capable subs will somehow be harder to EQ. You could actually argue that more headroom gives you more scope to apply boosts without it causing problems.
 

rccarguy2

Well-known Member
Personal pref I guess, I'd happily but 4 18" subs in this 11 x 17ft room if the neighbors wouldn't call the police and by budget allowed.

How hot do you run it? I tried mine at +12db and it's sounds stupid just too much bass. Someone places a mug on the table and it's like a grenade going off
 

rccarguy2

Well-known Member
Same reason getting 300w amp for side and rears was overkill, and money should have been put somewhere else...so kinda regret spending so much on side/rear amplifiers.
Should just reuse my 100w amps
 

Ultrasonic

Well-known Member
Just to expand a bit on the point of whether you're reaching limits or not, with a single BK Monolith in my room it maxed out on real-world content at about the 85 dB level. With a single PSA S1510 it can do 100 dB on the same material and I've not yet pushed it further to see where it actually hits its limits. An S1512 should have slightly higher output capability I think. This is in a room only slightly larger than yours @Harkon321 .

Here's an old post with an early comparison:


You may want more than this, and the example isn't for one that pushes the limits at 20 Hz or below, but just making the point that there is scope for a big jump in capability over what you have without getting into multiple large ported sub territory.
 

Ultrasonic

Well-known Member
I’ve got a umic but not used it yet.

Great. My advice would be to use it to help you make a more informed choice of what to buy then :) .
 

KelvinS1965

Distinguished Member
I don't think it hurts to have some headroom. Distortion will tend to rise rapidly as the headroom limit is approached, so designing your room to allow you to run below this limit in your expected use would make sense. Better than running your subs near the limit all the time. To use the motoring analogy; that's like buying a Fiat Panda for long drive down an autobahn.

I went for a target of being able to hit 115dB from 20Hz upwards when I started my room. I went slightly over that as it turned out, but that means for my typical film listening levels of -10dB below reference I've got more than 10dB headroom in hand. That allows me to run a bit of a house curve too and still enjoy lower distortion.

After I built the room and did all the setting up, I also did some compression testing, so I could see where the subs start to reach their limits. That meant I could set a limiter in the sub amp (passive DIY subs driven by external iNuke amps) so the drivers are protected. In practice they don't get close to that limit, but bass is really clean sounding.

Compare to years ago when I ran a single BK Monolith and that wasn't as clean sounding and I could always tell where the bass was coming from (it was on the right of my screen). Partly because I only had a single sub and had room null issues (resolved in the new room), but also because it was running close to it's limits at times. I actually blew the driver twice, which gives some idea of how close it was running.

FWIW I'm running 2 quite large, but sealed 15" subs each driven by an iNuke DSP6000 amp (around 1500 watts RMS into 4 ohms). Room size is 6.5 x 3.8 x 2.4 metres.
 
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rccarguy2

Well-known Member
Talking of sub peak limitor I'm trying it out on my lexicon mc-8. So initially I did this

Set svs sub to -10db on amp plate
Calibrate lexicon to 78db on lexicon to check range is somewhere in the middle.
Run antimode calibration
Calibrate to 78db from the Lexicon
Now trying the lexicon sub peak limitor, it got to 105db on the lexicon sub peak limitor before antimode led clipping, sub audibly reaching cone limits but safetly

So what I've done is change svs sub to -5db on amp plate
Recalibrated lexicon sub level to 78db
Rerun lexicon sub peak limitor and now gets to 107db on the lexicon before antimode led clips.

Does this mean at upper limits of my sub the signal to the sub will be cleaner less likely to have distortion, as not over saturating the arc in the antimode?

I've just enabled the antimode sub sonic filter (that's at 10hz) and I get another 2db so now 109db on lexicon sub peak from the sbu13 until it sounds like it's reaching its limit.

Really like the lexicon sub peak limited feature..granted if I had quad jtr rs2 I would never need it, bit say if I had a bk gemeni, it would be incredibly useful. Came in handy with a older lower class rel sub years ago.
 

KelvinS1965

Distinguished Member
Not sure about your set up. It sounds more like a question about over-driving the input of the Antimode unless I missed something? I had one years ago (back when I had the Monolith), but can't remember much about it, except that it was quick and easy to use.

What I did was run successive sweeps in REW, slowly turning up the master volume. When you reach a point where the master volume went up by 1dB from the last sweep, but the trace goes up by less than 1dB, then you are at the point of compression. I think my nerve took over before the subs really got to that point (whilst wearing ear defenders I should add :D).

I'm sure I did some more another time, but I found these from when I first finished my room as an example. This was with 4 subs (2 front and 2 rear), but this year I took the rear ones out as I found that with all the room treatment I'd put in that the two front ones worked better. I was actually getting some cancellation, so the levels are higher now with 2 less subs. Can't find those sweeps now, but this should illustrate the idea:

Sub power sweeps.jpg
 

Liammonty123

Well-known Member
I’ve got dual ported 21s in a 1000cuft room. They are capable of 120db upwards from 15hz upwards. I like to watch most films at reference, and with releases like Tenet and BR2049, they sometimes hit above 120db. At these levels the impact is extremely visceral and certainly gives that ‘pinned to chair’ effect you are looking for. Granted even at these levels they are at about 70% max, but they still sound very clean doing so.

Its just a question really of what levels you like to listen at. If you are a bass head like me then you may want to consider larger subs, whilst also carefully considering placement options.
 

KelvinS1965

Distinguished Member
And also considering your hearing. ;)

Im not joking either; working on cars and playing drums and guitar won’t have helped, but I suffer with tinnitus these days. :(
 

BriD

Well-known Member
More subs is better for an even response around the room, and I'd personally go for sealed as they're a ton easier to integrate than ported imho.

There's no such thing as too much sub but generally a heftier driver gives a slightly slower sounding bass. I.e. you might be better with say 4x10' than 1x18'. Maybe. Depending on preferences and a lot of luck. 😁
 

Conrad

Moderator
You can't overdo it, but Ultrasonic made a good point here and in another thread, you start to get diminishing returns. Both in terms of cost, and space. It becomes wasteful.

It's certainly not the most cost effective way to do it but I have great TR in my room from sealed subs - mostly because I'm on a suspended floor. I have 6 15" drivers in <800 cubic feet (four subs, two dual opposed 15" and two single 15") and I can hit over reference, including a loudness curve at 5Hz. At 10Hz and 120dB I have about 3% distortion - REW doesn't show distortion below 10hz. I suspect I could get rid of some of the subs and get a very similar effect at the actual volumes I listen at.

Even with that output, the response is controllable and balanced with the mains, so it's not like if you go slightly overkill on the subs you'll end up with a response you can't do anything with.
 

willz

Active Member
How hot do you run it? I tried mine at +12db and it's sounds stupid just too much bass. Someone places a mug on the table and it's like a grenade going off

Run what? Monolith +, I run it at 12 o clock, DB at 0, but in movies need to move it to between -4 and -10db on my amp or it can overwhelm the main sound.

To be fair I could too easily destroy this sub, it does the lows better but it's just no louder than my PC speakers, quality is better, but in terms of loudness and if I didn't have neighbours I'd want much louder.
 

Ultrasonic

Well-known Member
@Harkon321 I'll post a graph showing the performance of my single subwoofer below but first I want to make a point about frequency sweep measurements. During these the sub is essentially only playing one frequency at a time which is very different to what happens in violent movie sequences like explosions or rockets taking off where there are lots of frequencies all at once. The graph in my thread I linked to showing my Monolith reaching its limits at around 85 dB was in this context. Frequency sweep tests would have shown higher peak levels.

For my PSA S1510, if I run a flat EQ I can't actually reach its limits where I have the gain currently set. For movies I run an EQ with a more peaked bass response though, for which I just made the following measurements:

S1510 Compression Test_peaked response.jpg


So this shows limits being reached below around 25 Hz but above this higher levels would be possible. I left the room for each of the measurements for repeatability but I really don't think I'd have wanted to be in the room for the loudest. These levels are seriously loud/violent, and cause things all over my house to vibrate, not just in the room where the sub is.

What the above graph doesn't show is how distortion increases as the volume gets up. Here's REW's distortion figures for the same five measurements:

S1510 Compression Test Distortion.jpg


There are questions over the accuracy of distortion measurements, and some contributions will be from things in the room resonating rather than purely what the sub is doing, but there is no denying we're getting to some high figures here below 30 Hz. More and larger subs would definitely improve this. For movies I'll be honest I do question how important this is though (as distinct from music), in that when these levels might happen is going to be for big explosions etc where the source signal is hardly 'clean' to begin with. However, I can't claim to have heard a lower distortion system reproduce similar levels to compare.

I'm not knocking those here who have way more capable subwoofer systems than me, but I do think for the OP's 3.8m x 3.5 x 2.3m room it is easier to get into overkill territory for most people than posts on this forum often tend to suggest. (For context my room is about 4.65 m X 3.35 m X 2.35 m.)

The advantages of multiple subwoofers for a more even response is a separate question of course.

Hopefully this gives some useful context to my 'it depends how loud and how low' someone wants to go affecting when there is 'too much sub' for a room to be useful.
 
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milano j

Active Member
My room is just a little larger than the OP room l was running one REL HT1508 and a T7I the 1508 was far too powerful even at respectable volume levels it was wasted in this size of room and its fabric ie "drywall no brick" which does matter so regretfully l sold both REL subs. wasn't really a fan of the T7i but the 1508 was in another league or 10 above in performance
So l downgraded firstly to a REL ht1205 of which once run in was performing great but l still felt l was missing out on some subtle low level bass and at times pretty directional sounding. l knew another ht1205 wouldn't really solve this issue so l decided to go for a REL T9i best move l have made and l feel l have found the perfect balance of bass for my room size and also for my house and also for my neighbor as l live in a semi detached also l would suggest you go for sealed subs faster cut off less boom ....if my room was a good bit larger l would have had two REL HT1508's where they would really excel and l miss the ht1508 but l had to be realistic here is my ht1205 and T9i limited Edition it's a work of art
 

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Branislav

Member
My new room is 3.8m x 3.5 x 2.3m. Dedicated room, sealed, literally seating and an AV cab in the room. Plan is two subwoofers, loads of placement options.

I've bought a huge amount of my equipment as ex demo or second hand for the new room. Currently all boxed ready to fit - MK IW150, MKIW95s, MKIW85s.

It's not a big room so shouldn't be hard to pressurize, but how big is big enough? I imagine at some point, if

An audio engineer will first calculate a base resonant frequency of that room and for your room is 45 Hz. Whichever speaker you put in, it cannot play anything bellow that frequency (it might be good to limit frequency range on your amplifier, if it has such an option).

Second - where you will put a subwoofer(s) to avoid "boom" sound - an unwanted coloration where one frequency is amplified by resonant waves. In technical terms - how to avoid stand waves. Subwoofers are easier to place than other speakers since our ear cannot detect a direction of where a low frequency sounds come from.

Finally - how much of those speakers you need depends on the sound volume you want to have and that depends mostly on speakers efficiency. For same sound "volume" (how loud is the system), the following two systems are equal: speakers efficiency 85 dB + power amplifier 300 W and speakers efficiency 95 dB + power amplifier of 30 W. These 2 are THE SAME! I will always point this out - power really does not mean anything.

My room is very similar to your, it is just 4.5m in length, 3.5m width and 2.4m in height and I am using 2 big floorstanders. I have a subwoofer but I really never use it, there is too much bass already (cannot avoid stand waves and coloration). Small rooms are sh*t for audio...

For your room, a calculator tells me that all sounds bellow 300 Hz will be colorized, so... good luck in speakers placement. Acoustic calculator: Room modes
 
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