[aceinc]

Many people say the Perlisten D212 & 215 subs are great, and they should be for the price they are asking.

In reviewing their design they appear to be "Push/Pull dual woofer." The purported purpose is to maintain linearity of the drivers.

In thinking about the affect of this type of alignment it seems to me it would be effectively an open baffle with twice the motor strength (or half the surface area).

Am I wrong?

My reason for looking at this is because I want to increase the 20-40hz in my current system and am trying to decide what to build. I currently have 2 GR Research dual 12" OB subs, 1 Rythmic audio 15" sealed sub and two 10" sealed Dayton Titanic subs. I would replace the two 10" sealed subs with something specifically designed for 20-40hz.

If the perlisten design offers an advantage I, being of limited budget, would look to build something similar.

[WGH]

If the perlisten design offers an advantage I, being of limited budget, would look to build something similar.

I have never seen or heard a Perlisten sub, looks interesting. My audio buddies have GR Research dual 12" OB subs and dual Rythmic Audio sealed subs. The two different REL subs I have owned blow them all away. Anybody can make a sub that will play into the teens and twenty's, building a fast sub that disappears and can blend seamlessly while still digging into the teens is hard to do.

If your 2 GR Research dual 12" OB subs, 1 Rythmic audio 15" sealed sub and two 10" sealed Dayton Titanic subs don't do it for you then it's time to step up and play with the big boys.

The Perlisten D212 is $7,995. A REL No.31 is $7000. For what it sounds like you are after then two REL No.32 would work perfectly except for the $10,000 each price.
https://rel.net/shop/powered-subwoofers/reference-series/no-31/

What's a guy to do? The REL Gibraltar G1 MkII show up used regularly, check Hi-Fi Shark. I got a new G1 MkII from Upscale Audio in Oct. 2023 for $4,395 (list $5,500). It's the real deal. You will never in a million years build a sub this good because there are no off-the-shelf parts available that can be bought to build one. And you will still need an amp.
https://www.audiocircle.com/index.php?topic=187300.msg1963493#msg1963493

Note: the original REL G1 subs are going for cheap, they look the same but are really old now and the 12" driver has a known design flaw that causes it to fail which is why there is a MkII.

[aldcoll]

With that kind of sub power and diversity I would first look at the room. 

A  $200 microphone would be a good start.

I used my ear and time to get a hinky odd shipped room to pretty decent and better then I thought.  All with DiY.

Plenty of threads here on AC.  The room is 1/3 to 1/2 of the room.  After may years I am kicking my self for waiting  till this winter.

Alan

[aceinc]

What's a guy to do?

I am very pleased with my bass for music. I would like more bass extension for HT.

<philosophy>
There are a couple of approaches to keep me out of bars & other places which would get me in trouble. I can make sawdust (using up my free time) & save money, or I can spend so much money I can't afford any other vices. I would prefer the former to the latter.
</philosophy>

The REL review was interesting and provides a target to shoot for.

[aceinc]

With that kind of sub power and diversity I would first look at the room. 

A  $200 microphone would be a good start.

I used my ear and time to get a hinky odd shipped room to pretty decent and better then I thought.  All with DiY.

Plenty of threads here on AC.  The room is 1/3 to 1/2 of the room.  After may years I am kicking my self for waiting  till this winter.

Alan

I have and have used REW to tune my subs to the room. It did make a difference.

It gets a bit tiring tweaking 5 different subs. There are two things I could still play with;

• Rejigger the DSP on my Crown XTI 2002 which drives my 10" Titanics to optimize each one individually before balancing.
• Rerun the Audyssey on my sound processor after all my sub twiddling.

I typically do not use Audyssey when playing music. only HT.

[WGH]

It gets a bit tiring tweaking 5 different subs.

I would like more bass extension for HT.

How big is your room? My first thought was you have tried all the subs in your list and found them lacking in one way or another. Not all at once 

I loved the sealed REL Gibraltar G2 sub, the 10" driver output was flat to 25 Hz which was perfect for music but the G2's output at 20Hz was 13 dB lower, not so good for the sci-fi movies I love. You might be running into the same lack of ultra-low frequencies with all the speakers you have. They may do 20 Hz but their output is a lot less than it is at 30 Hz. The Crown XTI 2002 amp is only 475W @ 8 ohms, that's not enough for strong 15-20 Hz performance either, my REL G2 had 450W for a single 10" long throw driver.

Unfortunately I don't have any experience with ported home theater speakers, that design may be just what your room needs if used only for home theater. The REL HT/1510 Predator is -6 dB at 20 Hz and only $1,699. A lot of people use REL HT subs for music too, the price is certainly lower than their Reference Series.
https://rel.net/shop/powered-subwoofers/serie-ht/ht-1510-predator/

Check out the REL Acoustics Fan Forum on Facebook. REL customer support is an active participant and answers questions. Maybe you can find out how ported subs compare to sealed. Forum members may have compared REL subs to other affordable brands like the SVS SB16-Ultra Subwoofer (-3 dB at 16 Hz). One may have flubby bass and one may have tight bass.
https://www.svsound.com/products/sb16-ultra

REL Acoustics Fan Forum
https://www.facebook.com/groups/RELFans

[WGH]

Find out what Mark built, that sub should do it.

I have a DIY 2x12 HT sub - literally can hear the joists move when that bomb hits at volume.

[aceinc]

How big is your room? My first thought was you have tried all the subs in your list and found them lacking in one way or another. Not all at once 

My room is ~15'x25'x9' my fronts & OB subs are ~4' off one of the 15' walls. I listen about 13' away from these speakers.

I run the 2 OB subs off the speaker output (effectively in parallel to) my Magnepan 2.7s which they stand next to. I run the 3 sealed subs in the rear of the room off of the sub out of my sound processor (Marantz AV 7704).

I have used REW to balance the subs. I do listen to all subs at once.

[WGH]

I was poking around the internet this morning and discovered that Audioholics has a big subwoofer review section with measurements. The reviews don't often compare subs but in one case they do, the Creative Sound Solutions SDX12 DIY Kit sub.
https://www.audioholics.com/subwoofer-reviews/css-sdx12

The main review page includes reviews of Perlisten R212s, Perlisten D215s and the REL Acoustics HT/1510 Predator II Sealed Subwoofer
https://www.audioholics.com/subwoofer-reviews


CSS SDX12 sub with sealed flat pack kit $560
https://www.css-audio.com/online-store/Subwoofers-and-Bass-Module-c159572511

Note that the Audioholics reviewer used a Behringer NX3000D amp which has 800W @ 4 ohms in bridged mode ($460)

"The SDX12 was capable of absorbing a surprising amount of power we suspect a more powerful amplifier may have achieved higher output."
"The compression test for this subwoofer was interesting. Basically, it didn’t compress. We ran out of amplifier power..."
"Group Delay was commendably low, falling below 1 cycle to well below 20hz."
"The deep bass output of this subwoofer is impressive when compared to the commercial competition. There are very few twelve-inch sealed subwoofers that can achieve this level. Further, moving up to the larger dual passive radiator kit is likely to gain 6-9 dB of additional output below 40hz."

[youngho]

In thinking about the affect of this type of alignment it seems to me it would be effectively an open baffle with twice the motor strength (or half the surface area).

Am I wrong?

Yes. Can see some discussion here: https://www.avsforum.com/threads/push-pull-subwoofer-theory.2434410/

[WGH]

Yes. Can see some discussion here: https://www.avsforum.com/threads/push-pull-subwoofer-theory.2434410/

Cool info, thanks 👍