Perlisten D215s: Is This the Most Accurate Subwoofer on the Planet?

[highfigh]

The push-pull sub design (where the drivers are in phase, but work one cone facing forward and the other facing the rear or cabinet interior) is not a new design.
M&K has been using it for decades with the same type of cabinet as this one. Linkwitz had offered a dipole version for almost as long.

The primary reason for this design is that it substantially reduces even order harmonic distortion (mostly the 2nd harmonic). The reason for this is that the drivers non-linearities are canceled by the pair moving in opposite directions in relationship to the magnet structure.

Unfortunately, this design has no effect on the odd-order harmonic distortion. You can see that in the graphs.

From the measurements, this is obviously a tremendous sub. I would, though, not consider buying this for several reasons:

• It's too expensive... you can buy a bunch of smaller subs for much less money that, in unison, will offer the same or better performance
• One gigantic sub doesn't offer stereo. $18K for a pair of subs? No, thanks.
• 6 or 8 smaller subs can offer much smoother in room response if you spread them out in the room
• This sub weighs 200lbs. Sorry, but I'm not buying anything that heavy.

Really? "As good, or better" from a bunch of smaller subs that can't operate as cleanly and have no choice but contribute to phase cancellations and comb filtering? And, how large is this room that it can have 6-8 subs?

If weight would prevent you from buying an incredible pair of main speakers, you still wouldn't? 200 pounds really isn't terribly heavy unless it has to be moved up stairs and even that can be done by rolling the shipping box up, with two people.

 

[Pogre]

Familiar with isobaric speaker arrangement? Those are usually facing each other and it's a great way to get a lot of low end from a small box, although they move in the same direction.Very big in car audio when I was doing that.

Yes I'm familiar with isobaric, but have never built or owned one. I know this isn't an all new thing, but I'm not aware of too many subs with this design, and even fewer have the build quality and power of this one. Kind of (a very expensive) perfect storm of engineering, high quality parts and power. Pretty cool, but I absolutely agree that one might be better off buying smaller subs in multiples for even better overall performance. This is one of those "if I were goofy rich" things. I'd get a couple of these at least.

 

[Pogre]

Really? "As good, or better" from a bunch of smaller subs that can't operate as cleanly and have no choice but contribute to phase cancellations and comb filtering? And, how large is this room that it can have 6-8 subs?

If weight would prevent you from buying an incredible pair of main speakers, you still wouldn't? 200 pounds really isn't terribly heavy unless it has to be moved up stairs and even that can be done by rolling the shipping box up, with two people.

Well... multiple subs set up properly are always better than one, unless the multiples are of very poor quality. 10k can get you 4 really good subwoofers that can be strategically placed for better performance over a larger area.

 

[highfigh]

Well... multiple subs set up properly are always better than one, unless the multiples are of very poor quality. 10k can get you 4 really good subwoofers that can be strategically placed for better performance over a larger area.

I hope that someone considering this level of performance would also consider room analysis and treatment, of some type. That, alone, can minimize the need to multiple subs in some cases.

 

[highfigh]

Yes I'm familiar with isobaric, but have never built or owned one. I know this isn't an all new thing, but I'm not aware of too many subs with this design, and even fewer have the build quality and power of this one. Kind of (a very expensive) perfect storm of engineering, high quality parts and power. Pretty cool, but I absolutely agree that one might be better off buying smaller subs in multiples for even better overall performance. This is one of those "if I were goofy rich" things. I'd get a couple of these at least.

Maybe it has to do with the end users thinking "I can't see it- why did I pay so much?".

 

[shadyJ]

Am I the only one wondering why Perlisten Audio didn't use Neodymium magnets for this sub? $9,000 screams "no corners cut," I'd expect neodymium for such a price, especially due to weight. 90 kilograms is waaay too much weight. @shadyJ do you think RS1 comes close to this..? Great review!

Neodymium isn't better than ferrite, merely lighter. You wouldn't want to use neodymium because it has much less surface area and can not disperse heat as well as iron ferrite. It would actually hurt performance to use a neodymium magnet with the same flux as iron ferrite in drivers like these. Iron ferrite can achieve the same flux (albeit with a lot more mass added) but acts as a much better heatsink.

 

[shadyJ]

This is exactly what I was thinking too! The extra driver basically adds little or nothing as far as overall spl and must be strictly for linearity and reducing distortion. Pretty inefficient, but like you said with 3k watts efficiency is a non issue.

No, the extra driver nearly doubles the output. It's moving nearly as much outward air mass as the forward-mounted driver. It is simply mounted in a way that uses internal air pressure to also counter-act non-linear motion from the other driver.

 

[shadyJ]

The push-pull sub design (where the drivers are in phase, but work one cone facing forward and the other facing the rear or cabinet interior) is not a new design.
M&K has been using it for decades with the same type of cabinet as this one. Linkwitz had offered a dipole version for almost as long.

The primary reason for this design is that it substantially reduces even order harmonic distortion (mostly the 2nd harmonic). The reason for this is that the drivers non-linearities are canceled by the pair moving in opposite directions in relationship to the magnet structure.

Unfortunately, this design has no effect on the odd-order harmonic distortion. You can see that in the graphs.

From the measurements, this is obviously a tremendous sub. I would, though, not consider buying this for several reasons:

• It's too expensive... you can buy a bunch of smaller subs for much less money that, in unison, will offer the same or better performance
• One gigantic sub doesn't offer stereo. $18K for a pair of subs? No, thanks.
• 6 or 8 smaller subs can offer much smoother in room response if you spread them out in the room
• This sub weighs 200lbs. Sorry, but I'm not buying anything that heavy.

If you just want low-distortion bass, you can get that from less expensive subs for sure. This sub is for those who are chasing after absolute state-of-the-art and have the money to do so. In a sense, this is for those who are shopping for Porsches and McLarens, not Civics and Camrys. Any of those cars will get you to your destination just fine, but some will do so with a great deal more precision. This sub doesn't make any sense for those on a tight budget, and your money will go further addressing room mode acoustic problems with a multi-sub system, no doubt. I agree that using a multi-sub system to take care of room modes should come first. However, if you have a lot of money and want the least compromised performance, these are a great choice.

 

[lovinthehd]

Neodymium isn't better than ferrite, merely lighter. You wouldn't want to use neodymium because it has much less surface area and can not disperse heat as well as iron ferrite. It would actually hurt performance to use a neodymium magnet with the same flux as iron ferrite in drivers like these. Iron ferrite can achieve the same flux (albeit with a lot more mass added) but acts as a much better heatsink.

I'd also expect neodymium would cost more?

 

[ryanosaur]

No, the extra driver nearly doubles the output. It's moving nearly as much outward air mass as the forward-mounted driver. It is simply mounted in a way that uses internal air pressure to also counter-act non-linear motion from the other driver.

I'm confused, here.
When I look up Push-Pull woofer configurations in the Alden and Dickason books, they don't mention any SPL 'bonus' the way they do for adding multiple Woofers in a standard multi-Driver configuration.
In short, everyone agrees on the even order distortion aspect of this... But beyond that, it just gets muddy.

Can you, or anybody, please clarify?

Thanks!

 

[ryanosaur]

I'd also expect neodymium would cost more?

Yes, even for a smaller sized magnet, as I understand it. Likewise, if I follow correctly, the neo magnet will likely still be stronger unless seriously undersized.

 

[TLS Guy]

I'm confused, here.
When I look up Push-Pull woofer configurations in the Alden and Dickason books, they don't mention any SPL 'bonus' the way they do for adding multiple Woofers in a standard multi-Driver configuration.
In short, everyone agrees on the even order distortion aspect of this... But beyond that, it just gets muddy.

Can you, or anybody, please clarify?

Thanks!

Having two drivers will get you 3db increase in output at the same power. However you can double the power input for a total of 6db.

My really big beef, is that for all the hype, this is a highly inefficient brute force design. In my book that is just not elegant and has no attraction for me.

What is required are highly efficient designs that also couple to the space in the room effectively and efficiently. I would have zero satisfaction, and felt I had accomplished little, with a design like that. There is nothing about that is really novel, only may be, better implementation of old well worn ideas.

 

[shadyJ]

I'm confused, here.
When I look up Push-Pull woofer configurations in the Alden and Dickason books, they don't mention any SPL 'bonus' the way they do for adding multiple Woofers in a standard multi-Driver configuration.
In short, everyone agrees on the even order distortion aspect of this... But beyond that, it just gets muddy.

Can you, or anybody, please clarify?

Thanks!

The push-pull configuration itself doesn't grant you any additional SPL over that of a normal two-driver sealed sub. In fact, it may have a slight cost in efficiency since the sealed internal volume tends to be smaller (although not that much since the Perlisten motors are so powerful). But a sub like this isn't out to win SPL drag races, it is trying to achieve the maximum possible sound quality, not sound quantity.

 

[TLS Guy]

The push-pull configuration itself doesn't grant you any additional SPL over that of a normal two-driver sealed sub. In fact, it may have a slight cost in efficiency since the sealed internal volume tends to be smaller (although not that much since the Perlisten motors are so powerful). But a sub like this isn't out to win SPL drag races, it is trying to achieve the maximum possible sound quality, not sound quantity.

Unless the drivers are connected in series then you can expect 3 db just based on dropping the impedance and then you double power handling and that adds another 3 db. That does not apply to an isobaric arrangement, so unless there is something very unusual about this box, like being much smaller than calculations would call for, then I don't understand why general principles would not apply here. After all both drivers are raditing on one side of the cone to the room, admittedly one from the rear of the cone, but I fail to see how that would affect output. If somehow they have sacrificed the increased output from two drivers, then this design is a real dog.
Apart from the drivers and extended x-max, I fail to see how this design has advanced the cause and moved us forward.

 

[Eppie]

The push-pull configuration itself doesn't grant you any additional SPL over that of a normal two-driver sealed sub. In fact, it may have a slight cost in efficiency since the sealed internal volume tends to be smaller (although not that much since the Perlisten motors are so powerful). But a sub like this isn't out to win SPL drag races, it is trying to achieve the maximum possible sound quality, not sound quantity.

Did you get a chance to ask about the S4b or R5t? Any chance we'll get to see a review on something from the lower tier?

 

[shadyJ]

Did you get a chance to ask about the S4b or R5t? Any chance we'll get to see a review on something from the lower tier?

There are other Perlisten speakers I would like to look at, and they are open to more reviews, so I am sure we will be seeing a review of some other Perlisten speakers in the future.

 

[jeffca]

Really? "As good, or better" from a bunch of smaller subs that can't operate as cleanly and have no choice but contribute to phase cancellations and comb filtering? And, how large is this room that it can have 6-8 subs?

If weight would prevent you from buying an incredible pair of main speakers, you still wouldn't? 200 pounds really isn't terribly heavy unless it has to be moved up stairs and even that can be done by rolling the shipping box up, with two people.

First off, given the frequencies being covered, comb-filtering is not a issue since the room reflections and nodes do more to degrade the bass response than having subs spaced out in the room. When the frequencies get below 100Hz, you'd need a huge room for comb filtering to even begin to become a consideration. You might want to research that.

I have a modest, finished basement and 4 Rythmik 12" servo subs in it where I use them as speaker stands for the front L/R speakers. There's enough space to easily add 4 more subs in the rear. 4 subs, though, are enough to cause the concrete floor to vibrate while still playing very cleanly.

As to the weight issue, each of these Rythmik subs weighs in around 55 lbs. All together, they weigh just a hair more than the Perlisten sub. When I need to move them, I don't mind that.

They can easily make it to 20 Hz and, aggregately, do it as cleanly as the Perlisten sub.

As to cost, they, in total, are around $2,200. Adding 4 more would still come in less than half the cost of the reviewed sub and blow that thing away in a room or a lab. Also, the servo system really does it's bit to decrease distortion.

In the end, low bass reproduction comes down to the total radiating area of the drivers. More drivers means more radiating area (two 12" drivers = one 18"). It also means less distortion since the drivers need to work much less hard to reproduce the low frequencies.

Also, there is no woofer on the planet that can take much more than 800 Watts at a sustained level. Most consumer woofers top out around 400. Having 3.5kW driving 2 woofers is a gigantic waste of money. It's BS. It is, though, a great marketing ploy to get the ignorant to spend $9K on a sub (it costs more so it must be better!).

Again, not saying that the Perlisten isn't a great performing sub, but, it's too big, too heavy and too expensive for my tastes.

This is from a bass player and audio engineer.

 

[shadyJ]

They can easily make it to 20 Hz and, aggregately, do it as cleanly as the Perlisten sub.

As to cost, they, in total, are around $2,200. Adding 4 more would still come in less than half the cost of the reviewed sub and blow that thing away in a room or a lab. Also, the servo system really does it's bit to decrease distortion.

In the end, low bass reproduction comes down to the total radiating area of the drivers. More drivers means more radiating area (two 12" drivers = one 18"). It also means less distortion since the drivers need to work much less hard to reproduce the low frequencies.

Also, there is no woofer on the planet that can take much more than 800 Watts at a sustained level. Most consumer woofers top out around 400. Having 3.5kW driving 2 woofers is a gigantic waste of money. It's BS. It is, though, a great marketing ploy to get the ignorant to spend $9K on a sub (it costs more so it must be better!).

Again, not saying that the Perlisten isn't a great performing sub, but, it's too big, too heavy and too expensive for my tastes.

This is from a bass player and audio engineer.

No offense, but your claims about the performance of your subs is just supposition until it gets measured. Also, two 12"s do not quite equal an 18". And there is more to drivers than cone area. It's nice that you are happy with your subs, but your comments reflect that you are missing the point of the Perlisten sub as well as misunderstanding basic design elements.

 

[highfigh]

View attachment 49654
First off, given the frequencies being covered, comb-filtering is not a issue since the room reflections and nodes do more to degrade the bass response than having subs spaced out in the room. When the frequencies get below 100Hz, you'd need a huge room for comb filtering to even begin to become a consideration. You might want to research that.

I have a modest, finished basement and 4 Rythmik 12" servo subs in it where I use them as speaker stands for the front L/R speakers. There's enough space to easily add 4 more subs in the rear. 4 subs, though, are enough to cause the concrete floor to vibrate while still playing very cleanly.

As to the weight issue, each of these Rythmik subs weighs in around 55 lbs. All together, they weigh just a hair more than the Perlisten sub. When I need to move them, I don't mind that.

They can easily make it to 20 Hz and, aggregately, do it as cleanly as the Perlisten sub.

As to cost, they, in total, are around $2,200. Adding 4 more would still come in less than half the cost of the reviewed sub and blow that thing away in a room or a lab. Also, the servo system really does it's bit to decrease distortion.

In the end, low bass reproduction comes down to the total radiating area of the drivers. More drivers means more radiating area (two 12" drivers = one 18"). It also means less distortion since the drivers need to work much less hard to reproduce the low frequencies.

Also, there is no woofer on the planet that can take much more than 800 Watts at a sustained level. Most consumer woofers top out around 400. Having 3.5kW driving 2 woofers is a gigantic waste of money. It's BS. It is, though, a great marketing ploy to get the ignorant to spend $9K on a sub (it costs more so it must be better!).

Again, not saying that the Perlisten isn't a great performing sub, but, it's too big, too heavy and too expensive for my tastes.

This is from a bass player and audio engineer.

When the same signal comes from multiple points at different distances to the mic, ear, etc, comb filtering will always happen. The point of using multiple subs is to smooth the peaks and valleys of the 'comb' but that doesn't address the ability of the subs to produce the sound with low distortion or respond quickly to the signal, with critical damping.

If you think nine grand is expensive, you should look around- there are many speakers that are priced much higher and may not sound as good.

 

[Kiwi_Alan]

FYI: The push-pull configuration was patented by Ken Kreisel in 1996 and used extensively in Miller & Kreisel (M&K) sub-woofers.

Kreisel Sound Timeline

The world’s top studios and recording engineers use speakers and subwoofers designed by Ken Kreisel.

www.kreiselsound.com