Sealed subs and room gain... - AVS Forum
Forum Jump: 
 
Thread Tools
post #1 of 16 Old 02-18-2014, 03:56 AM - Thread Starter
Senior Member
 
Trace79's Avatar
 
Join Date: Dec 2012
Posts: 233
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 29
Can anyone help me understand this a little better? I'm under the impression that sealed subs do better in a small closed off room due to room gain. Don't all subs do better in smaller spaces? I've read that sealed subs are even preferred in smaller rooms due to this. Does this help them dig deeper or does it help in other frequencies?
Trace79 is offline  
Sponsored Links
Advertisement
 
post #2 of 16 Old 02-18-2014, 04:51 AM
AVS Special Member
 
bear123's Avatar
 
Join Date: Dec 2013
Location: PA
Posts: 2,444
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 148 Post(s)
Liked: 661

This is mainly due to helping them improve output at low frequency, unlike a ported sub, which won't gain as much, since they roll off much more sharply below their port tuning.

 

Sealed subs typically start rolling off much earlier than an equivalent ported sub, say, around 30-40 Hz.  Room gain will flatten this out and cause low frequency output to remain much higher.  A ported sub will often still hold some advantage close to its port tune, down to which point they tend to be very flat, followed by a sharp drop off.  Room gain usually only adds a couple of Hz in extension to a ported sub.

 

A ported sub will be fairly flat down to port tune, say 18-22Hz(some lower) regardless of room size.  A sealed sub must have a small enough room to maintain a flat response.


AVR:       Yamaha RXV-375

Display:  Panasonic  TH-50PC77U

LCR:       Hsu HB1.2  HC1.2

Sub:       (2) PSA XV15se

Blu Ray:  Sony BDP-S5100

Apple TV

Harmony 650

miniDSP

bear123 is offline  
post #3 of 16 Old 02-18-2014, 05:07 AM
AVS Special Member
 
Bill Fitzmaurice's Avatar
 
Join Date: Nov 2009
Location: New Hampshire
Posts: 9,322
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 1221
Quote:
Originally Posted by Trace79 View Post

Don't all subs do better in smaller spaces?
They do.
Quote:
I've read that sealed subs are even preferred in smaller rooms due to this. Does this help them dig deeper or does it help in other frequencies?
The reason sealed subs are generally preferred in rooms small enough to use them is that sealed subs are smaller. The advantage to a small room is that you don't have to use larger ported subs in them to reach flat to 20Hz.. But you can.
Quote:
This is mainly due to helping them improve output at low frequency, unlike a ported sub, which won't gain as much, since they roll off much more sharply below their port tuning.
Ported and sealed subs will realize exactly the same cabin gain in the same room. The significance of the roll off slope between sealed and ported is vastly overstated; with well designed subs of both types a difference in the end result will only be seen below 15Hz, which is of little consequence to most users.
oneeyeblind likes this.

Bill Fitzmaurice Loudspeaker Design

The Laws of Physics aren't swayed by opinion.
Bill Fitzmaurice is online now  
post #4 of 16 Old 02-18-2014, 05:08 AM
AVS Special Member
 
flickhtguru's Avatar
 
Join Date: Mar 2008
Location: Lebanon, PA
Posts: 2,458
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 105
I don't want to take credit but this is from Bill Fitzmaurice: you take 565 divided by the room's longest dimenstion and that is the frequency where room gain will start. So for a room with a longest dimension of 18ft the room gain would start around 31.5hz. So if you had a room like that then you would want a sealed sub flat to about 30hz then room gain would help you from there down.
bear123 likes this.

Shawn
flickhtguru is offline  
post #5 of 16 Old 02-18-2014, 08:58 AM
Senior Member
 
ClawAndTalon's Avatar
 
Join Date: Jan 2014
Posts: 323
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 26 Post(s)
Liked: 86
Quote:
Originally Posted by flickhtguru View Post

I don't want to take credit but this is from Bill Fitzmaurice: you take 565 divided by the room's longest dimenstion and that is the frequency where room gain will start. So for a room with a longest dimension of 18ft the room gain would start around 31.5hz. So if you had a room like that then you would want a sealed sub flat to about 30hz then room gain would help you from there down.

So how much extra room gain will you get, like flat for another 10 hz down to 20 for example?  

 

I have a sealed room with an 18 ft long wall as it so happens, and I've tossed around the idea on a sealed sub. Many of them roll off at or around 30. 

ClawAndTalon is offline  
post #6 of 16 Old 02-18-2014, 09:34 AM
AVS Special Member
 
Bill Fitzmaurice's Avatar
 
Join Date: Nov 2009
Location: New Hampshire
Posts: 9,322
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 1221
Quote:
Originally Posted by ClawAndTalon View Post

So how much extra room gain will you get, like flat for another 10 hz down to 20 for example?
 The theoretical maximum is 12dB/octave, though 8-10dB is more realistic in an average room.
Quote:
I've tossed around the idea on a sealed sub. Many of them roll off at or around 30. 
That would be on the low side, and I'd want to see measurements before I believed it.

Bill Fitzmaurice Loudspeaker Design

The Laws of Physics aren't swayed by opinion.
Bill Fitzmaurice is online now  
post #7 of 16 Old 02-18-2014, 09:38 AM
Senior Member
 
ClawAndTalon's Avatar
 
Join Date: Jan 2014
Posts: 323
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 26 Post(s)
Liked: 86
Quote:
Originally Posted by Bill Fitzmaurice View Post


 The theoretical maximum is 12dB/octave, though 8-10dB is more realistic in an average room.
That would be on the low side, and I'd want to see measurements before I believed it.

Bill, it would appear that the new SVS SB2000 begins it's roll off at 30 hz according to their website. 

 

So I'd possibly be at 20 hz or close to it before a roll off on that sub?

 

Not to mention EASILY getting single digits with the gentle roll off... Unless I'm missing something 

ClawAndTalon is offline  
post #8 of 16 Old 02-20-2014, 08:26 PM - Thread Starter
Senior Member
 
Trace79's Avatar
 
Join Date: Dec 2012
Posts: 233
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 29
Quote:
Originally Posted by ClawAndTalon View Post

Bill, it would appear that the new SVS SB2000 begins it's roll off at 30 hz according to their website. 

So I'd possibly be at 20 hz or close to it before a roll off on that sub?

Not to mention EASILY getting single digits with the gentle roll off... Unless I'm missing something 

I too was looking at the SB-2000 for my room...well, duals actually. My room is very small at 14' x 9' x 8' and there is little room for a big ported sub. The only ported sub worth its salt I can have would be a SVS cylinder (was thinking the PC12+). The largest sealed sub I could get would be the SB13-Ultra. I know the Sb13 would be massive overkill in that room biggrin.gif and a pc12+ would probably be more than enough but I would lack the benefit of having duals. Two SB-2000's come to mind but I wonder if I would get that low-end from room gain that would match or come close to the pc12+? I also wonder if the SPL from 40hz and up would be more/less than a pc12+. Placement of duals SB2000 would be easy though.
Any thoughts?
Trace79 is offline  
post #9 of 16 Old 02-20-2014, 08:51 PM
AVS Special Member
 
basshead81's Avatar
 
Join Date: Mar 2013
Location: Fort Wayne, IN
Posts: 5,618
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Liked: 1342
Quote:
Originally Posted by Trace79 View Post

I too was looking at the SB-2000 for my room...well, duals actually. My room is very small at 14' x 9' x 8' and there is little room for a big ported sub. The only ported sub worth its salt I can have would be a SVS cylinder (was thinking the PC12+). The largest sealed sub I could get would be the SB13-Ultra. I know the Sb13 would be massive overkill in that room biggrin.gif and a pc12+ would probably be more than enough but I would lack the benefit of having duals. Two SB-2000's come to mind but I wonder if I would get that low-end from room gain that would match or come close to the pc12+? I also wonder if the SPL from 40hz and up would be more/less than a pc12+. Placement of duals SB2000 would be easy though.
Any thoughts?

There is no such thing as overkill, you can always turn the sub down and the less it has to work to achieve a desired output level, the better it will sound. That being said the sb13 and pc12+ would be similar in output above 30hz, the pc+ would have a bit more below 30hz.
basshead81 is offline  
post #10 of 16 Old 02-20-2014, 09:31 PM - Thread Starter
Senior Member
 
Trace79's Avatar
 
Join Date: Dec 2012
Posts: 233
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 29
Yes
Quote:
Originally Posted by basshead81 View Post

There is no such thing as overkill, you can always turn the sub down and the less it has to work to achieve a desired output level, the better it will sound. That being said the sb13 and pc12+ would be similar in output above 30hz, the pc+ would have a bit more below 30hz.

Yes, I know I can always turn the gain down. But knowing my friends and I when we get drunk would be like when a redneck says, "hey yall, check this out!" biggrin.gif

If I did get an SB13 it would go under the desk where the TV sits, facing the MLP and only about five feet away. Same if I got dual SB2000s, but one would go somewhere else.

The PC12+ would be tucked away in a corner.

If I could get below 20hz at decent SPL with a sealed sub, this would be preferred.
Trace79 is offline  
post #11 of 16 Old 02-20-2014, 09:57 PM
AVS Special Member
 
derrickdj1's Avatar
 
Join Date: Sep 2011
Posts: 1,364
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 55 Post(s)
Liked: 139
Even though sealed subs are great for smaller rooms, sealed subs can be used in a larger HT. I run Chase subs SS 18.2 and stacked SS 18.1 in a 5300 cu ft space and have excellent output/LFE. Four 18 in drivers move a lot of air for a good pressure effect. These passive subs are smaller than the Rythmik and HSU ported 15 in. subs.

Klipsch RF 7 based HT 7.4, Pioneer SC 35, Acurus Five 200 amp, Chase SS 18.2(2), VS 18.1(2), Samsung BDP F 7500, Asus/My Book Live HPC 4 TB

Yaquin VK 2100 amp, McIntosh XR 5 speakers, Samsung BDP F 7500
derrickdj1 is offline  
post #12 of 16 Old 02-21-2014, 12:56 AM
AVS Special Member
 
fatbottom's Avatar
 
Join Date: May 2003
Location: UK
Posts: 3,335
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 204 Post(s)
Liked: 142
Quote:
Originally Posted by Trace79 View Post

I too was looking at the SB-2000 for my room...well, duals actually. My room is very small at 14' x 9' x 8' and there is little room for a big ported sub. The only ported sub worth its salt I can have would be a SVS cylinder (was thinking the PC12+). The largest sealed sub I could get would be the SB13-Ultra. I know the Sb13 would be massive overkill in that room biggrin.gif and a pc12+ would probably be more than enough but I would lack the benefit of having duals. Two SB-2000's come to mind but I wonder if I would get that low-end from room gain that would match or come close to the pc12+? I also wonder if the SPL from 40hz and up would be more/less than a pc12+. Placement of duals SB2000 would be easy though.
Any thoughts?

I use a SB Ultra 13 in a 3.5 m x 3m room. Sounds great, not overkill (tried SB 12" and needed more grunt for movies) the 12" didn't rumble the room like the 13.5" can.

Krell Evolution 900e x 7

Bose Jewel speakers.

 

Jealous of my speakers?

fatbottom is online now  
post #13 of 16 Old 02-21-2014, 01:53 AM
Advanced Member
 
kramskoi's Avatar
 
Join Date: Dec 2005
Location: south-central Louisiana
Posts: 507
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 26
Quote:
Originally Posted by Trace79 View Post

I too was looking at the SB-2000 for my room...well, duals actually. My room is very small at 14' x 9' x 8' and there is little room for a big ported sub. The only ported sub worth its salt I can have would be a SVS cylinder (was thinking the PC12+). The largest sealed sub I could get would be the SB13-Ultra. I know the Sb13 would be massive overkill in that room biggrin.gif and a pc12+ would probably be more than enough but I would lack the benefit of having duals. Two SB-2000's come to mind but I wonder if I would get that low-end from room gain that would match or come close to the pc12+? I also wonder if the SPL from 40hz and up would be more/less than a pc12+. Placement of duals SB2000 would be easy though.
Any thoughts?
Well I can tell you that with a 14' length...your room gain should start at about 40Hz. You will have a modal peak at about 40Hz, like my room (14x11x8), where I had to make a big cut from 35 - 45 Hz after the Linkwitz Transform was engaged. I don't think the SB-13 Ultra would be overkill at all. You are looking at an estimated 4 liters of displacement peak to peak [assuming 30 - 32mm xmax x 635 cm^2 Sd]. Bosso's formula says you need 10 liters peak to peak for the "real deal" (1008 cu. ft. x .01]. I say [one way displacement / cubic feet] should be higher than 40 for a "compelling" experience. With one SB13, you will be at 20, best case [32mm xmax]. I am not sure of the xmax capabilities of the Ultra driver, but I would guess around 30 mm or better. Overkill starts at two or more...wink.gif

"Frequency response is NOT efficiency response."

 

Klipsch RB-35's main

Klipsch RB-35's surround

Acoustech HT-65 center

Cerwin-Vega CV-2800

 

Subwoofer

B&C 21SW152-4  [21" critical-Q]

 

kramskoi is offline  
post #14 of 16 Old 02-21-2014, 02:51 AM
Senior Member
 
Lecter83's Avatar
 
Join Date: Aug 2012
Location: España / Asturias - Gijón
Posts: 377
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 38
Quote:
Originally Posted by kramskoi View Post

With one SB13, you will be at 20, best case [32mm xmax]. I am not sure of the xmax capabilities of the Ultra driver, but I would guess around 30 mm or better. Overkill starts at two or more...wink.gif

According to the review of its big brother the hometheaterhifi PB13 web, reads as follows:

The driver does not end just with an extra inch and a half in size. It is capable of 3" excursion, which means it can move a lot of air.
http://www.hometheaterhifi.com/volume_14_3/svs-pb13-ultra-subwoofer-9-2007-part-1.html

It's a really rough, not exact. But perhaps it can serve as a reference and I guess the tour between SB13 and PB13 will be similar.

I add:

3" tour seems excessive to me, I have no reason to doubt the data, but I think it's best to ask Ed Mullen to be sure.
Lecter83 is online now  
post #15 of 16 Old 02-21-2014, 03:09 AM
AVS Special Member
 
fatbottom's Avatar
 
Join Date: May 2003
Location: UK
Posts: 3,335
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 204 Post(s)
Liked: 142
I read the SB Ultra 13 driver has a bit more cone excursion compared to the PB/PC models..

Krell Evolution 900e x 7

Bose Jewel speakers.

 

Jealous of my speakers?

fatbottom is online now  
post #16 of 16 Old 02-21-2014, 05:24 AM
Senior Member
 
ClawAndTalon's Avatar
 
Join Date: Jan 2014
Posts: 323
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 26 Post(s)
Liked: 86
Quote:
Originally Posted by Trace79 View Post


I too was looking at the SB-2000 for my room...well, duals actually. My room is very small at 14' x 9' x 8' and there is little room for a big ported sub. The only ported sub worth its salt I can have would be a SVS cylinder (was thinking the PC12+). The largest sealed sub I could get would be the SB13-Ultra. I know the Sb13 would be massive overkill in that room biggrin.gif and a pc12+ would probably be more than enough but I would lack the benefit of having duals. Two SB-2000's come to mind but I wonder if I would get that low-end from room gain that would match or come close to the pc12+? I also wonder if the SPL from 40hz and up would be more/less than a pc12+. Placement of duals SB2000 would be easy though.
Any thoughts?

To help you with due diligence, check and see if the PSA XS15, or the perhaps even the XS30 has dimensions which would be suitable for your room. PSA also has the XV 30f, which is a ported sub with two front firing 15"s stacked vertically (to save space). But, again check and see if the footprint and dimensions would work for you. YMMV and yade yade, but I personally don't think you'd get much gain from duals in that listening space as long as there are no audible nulls in your sitting area. That's just me though...

 

Room gain is always going to be tricky. The long wall formula, while being a decent first step, is a very general rule. Different subs, and more importantly different rooms, and their contents (bed, sofa etc) will skew the appropriate answer for your particular listening space. http://www.data-bass.com/data?page=content&id=80

ClawAndTalon is offline  
Reply Subwoofers, Bass, and Transducers

User Tag List

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off