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Sealed sub - choice and quantity
Sealed sub - choice and quantity
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Old 1st February 2019, 11:45 AM   #1
stretchneck is offline stretchneck  United Kingdom
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Default Sealed sub - choice and quantity

Hi,

I will shortly be building a pair of Jeff Bagby's Spirit Wind 2 way monitors - these use the Audio Technology 18H mid/bass driver.

I'm going to extend their response with subs, but cannot decide on what would work best in my 5m by 5m room (which I understand is the worst shape!).

The sub's would be sealed and use NCore plate amps, or multichannel power amp plus DSPmini, to do a linkwitz transform (if necessary) to extend the frequency response if needed. I'm targeting flat down to 30Hz at 90dB.

Option 1: Pair of subs acting as stands for the monitors (Like Jeff's Kairos 3 ways), but using the Audio Technology Flexunits 10" or 12" driver - these drivers are quite expensive! Also I don't know if they'd be a good match for a sealed sub?

Option 2: Same as above, but using either SB acoustics 12" sb34nrx75-6 or 15” SB42FHC75-6, Dayton Audio RSS315HFA-8 12" Reference HF or RSS460HO-4 18".

Option 3: Multichannel power amp and four subs using cheaper Dayton audio RSS265HF-8 10" Reference HF. But enclosures would have to be smaller I guess.

What would likely be the 'better' solution? I'm aiming for low group delay, fast transient response and a dynamic sound.

I am presuming that larger Sd is always better!

Last edited by stretchneck; 1st February 2019 at 11:56 AM.
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Old 1st February 2019, 11:57 AM   #2
scottjoplin is offline scottjoplin  Wales
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Option 3
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Old 1st February 2019, 01:11 PM   #3
Windforce85 is online now Windforce85  Poland
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Use RSS265HO-4 driver as most suitable for subwoofer of your preference by a fair margin (do not ask why at this stage), then mix 2nd and 3rd option building compact subwoofers pair as stands for monitor and another identical pair of subwoofers placed at the opposite side of the room, at your back. Another best 10" drivers available for this kind of installation are Peerless XLS10 (P830452) and Seas L26R4OY. You will need to do Linkwitz-transform on the DSP but it is perfectly normal.

Then apply delays to either front or back pair of subwoofers (in case of front pair, obviously delay all three ways) which is equal to the distance between front and back subwoofers. Additionally, try flipping the phase of pair at your back.

Experimentally find best bass response which is characteristic to your particular room and your listening place, but of course you can evaluate it in measurements using cheap UMIK-1 USB mic and REW software which is free.

Last edited by Windforce85; 1st February 2019 at 01:19 PM.
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Old 2nd February 2019, 08:01 AM   #4
stretchneck is offline stretchneck  United Kingdom
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RSS265HO-4 is definitely the best choice - thanks for pointing it out to me.

I also had another nice idea - having 4 smaller subs also provides for the possibility of a stacked pair under each of the monitors as well as the likely better option of placement 2 front and 2 rear - so allows some good flex with placement.

Many thanks once again - nice to have feedback on ideas. I'll post some feedback on build once it occurs (I have the drivers for the Spirit Winds, just need to start building).
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Old 2nd February 2019, 10:01 AM   #5
Windforce85 is online now Windforce85  Poland
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It is possible to use REW room mode simulator which can loosely estimate room mode suppression via 4 identical LF devices before even you build it. Remember, REW results are only estimation, not simulation and real-life results are often slightly different by all means.

Another possibility is to use random subwoofers placement and Multi Sub Optimizer software. Having compact subwoofers is always convenient from this point of view. From my memory, best sound was obtained everytime when one pair of LF extensions was placing close to monitors, creating 3 way stack. Hiding subwoofers under sofa caused seat to vibrate what is not welcome behaviour in music (but in HT - yes!).

Last edited by Windforce85; 2nd February 2019 at 10:03 AM.
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Old 2nd February 2019, 10:04 AM   #6
scottjoplin is offline scottjoplin  Wales
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It's much easier if you only need good bass over a small area and can move your listening position
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Old 2nd February 2019, 10:31 AM   #7
stretchneck is offline stretchneck  United Kingdom
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Thanks guys
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Old 2nd February 2019, 11:08 AM   #8
poseidonsvoice is offline poseidonsvoice  United States
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Sealed sub - choice and quantity
Hi!

Stretchneck, this link may prove to be useful to you:

Tuning multiple subs

Also, I posted a step by step recommendation here:

Budget subwoofer 'swarm'?

Best,

Anand.
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Old 9th February 2019, 08:52 PM   #9
stretchneck is offline stretchneck  United Kingdom
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Hi,

So have been reading the provided information. REW room mode simulator seems to suggest that a single sub-woofer placed exactly in the middle of the front wall would be best. Multi-sub does provide smoothing of response depending upon listening position, but the benefit appears to be otherwise minimal?

Really glad that REW room mode simulator was suggested to me - but REW would suggest that a single sub is best?... Seems that a square room is a pain!
Attached Images
File Type: png Square Room single sub.png (353.9 KB, 191 views)
File Type: png Square room four subs.png (379.6 KB, 191 views)

Last edited by stretchneck; 9th February 2019 at 09:18 PM.
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Old 10th February 2019, 02:04 AM   #10
Think is offline Think  Netherlands
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Sealed sub - choice and quantity
Exactly in the middle of 2 walls is going to create big nulls or cancellations, everywhere in the room.

option 3 Multiple mono sealed small subs not to far apart ( <1/4 wavelength in theory) from each other, near your tops and near corners or at least against walls sounds best to me. If you have more then 2 it's worth to elevate 1 or more.
1: phi (golden ratio) or about 5:8 is best to use when placing speakers, especially for your tops.


If your speakers are closer to the ceiling then the floor (and should also not be half way) then hanging the subs at the ceiling also makes sense. Often not very practical, but best to do with small sealed subs because of their size and weight.

IMO sealed sounds best by far and smaller rooms compensate for the roll off and if needed a little lows boost is fine to use.
Don't EQ the life/feel out of it.

Last edited by Think; 10th February 2019 at 02:08 AM.
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