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

[Danzilla31]

Wow Shady those results are very impressive! Especially for a sealed sub. For that price tho as you say they should be that good. Great review

 

[shadyJ]

@shadyJ
That is some high praise!
While you were there, did you get to play around with it in a listening environment?

No, this sub was far too heavy for me to do a full review. But hey, it sounded great with the test tones!

 

[luis1090]

This design reminds me of the M&K subwoofers from maybe 10? years ago. If I remember right they were well regarded and had many positive reviews. Nothing remotely as massive and powerful as this Perlisten but it have me wondering if any of those engineers have any input in this design because is really close in design and I don't know of any other current company using this design.

 

[ryanosaur]

This design reminds me of the M&K subwoofers from maybe 10? years ago. If I remember right they were well regarded and had many positive reviews. Nothing remotely as massive and powerful as this Perlisten but it have me wondering if any of those engineers have any input in this design because is really close in design and I don't know of any other current company using this design.

This type of build is cool, but most people want the Drivers to add to output rather than simply improve distortions. Any kind of isobaric or push-pull design uses that extra driver to achieve different goals than SPL, so whether its a $50 Driver or a $400... you can see how that might add up.
Can you imagine a Funk or Harbottle Driver being doubled up like that?

I'm impressed that these guys went after this in such a way. It's a commitment to be certain!

 

[TLS Guy]

The push-pull creates a positive and negative pressure, but since the drivers are playing out of phase yet are mounted in opposite directions of each other, the pressure that they cause in the sealed cavity helps to reduce the nonlinear travel that only occurs in one direction of the driver's travel. Think of the air as a direct mechanical link between them. If the driver has a problem in the inward excursion, the linear outward excursion from the other driver pushes the problematic inward travel of the first driver into greater linearity. The force of the opposite driver uses air pressure to induce better behavior for the adjacent driver.

That is right. I await the measurements with interest.

I can't believe that the design concept of this speaker has much merit. Worse I think your open air measurements will be totally misleading in terms of how this speaker would actually behave in a room.

First of all this speaker may be a sealed box, but it will not behave anything like a sealed box speaker as we have come to know them.

Since the speakers are out of phase, sure there will be a coupling. However both positive and negative pressures in the box will be cancelled apart from any non linearity between the divers. So the closed box model would not apply in any meaningful sense whatsoever. So essentially there will be NO restoring force from the box on the drivers. So the restoring force has to be provided almost entirely by the suspension of the drivers. So this is much more akin to the infinite baffle model and not the sealed model.

However there is a significant difference. In the classic IB model there is only forward radiation. The rear radiation is lost in the huge space behind the driver which should not connect with the room. So there is no cancellation. The system Q in these systems closely follows driver Q and restoring force is from the driver suspension entirely.

Now this speaker is a Dipole as the speakers are out of phase, and so side radiation will be cancelled. This has to be the radiation pattern.

Note the nulls either side of the speaker. However unlike a Quad ESL for instance, a sub is dealing with very large wave lengths, greater than the width of the cabinet by far. So front back cancellations will be far more significant I suspect. So no wonder they need such an enormous xmax. This I fear is likely to lead to deterioration over time, due to increased laxity of the suspension, having to provide the restoring force. This has long proved to be the achilles heel of IB designs.

I have the strong suspicion that free air measurements of this speaker may differ greatly from in room performance.

This seems to me an inherently highly inefficient design due to cancellations from the out of phase speaker design. I am highly sceptical that the non linearity of backward and forward motion, is going to be improved by the inherent coupling of the drivers in this design. My intuition is that the huge driver excursions required will negate that advantage and actually be worse, especially over time.

There is no way that this can be an efficient design, and has to be very much in the brute force category, which as I think you know, I abhor.

Good design always works with nature's forces, to create synergy and mechanical advantage, which enhances efficiency and reducing stress on mechanical parts.

I would actually wager pretty good money, that my TLs which do not require sub drivers, would outperform that design concept. The Proms started a week ago and there was a really good performance of the Poulenc organ concerto. Daniel Hyde let the voice of Jupiter really rip and the whole room really shook, with the drivers barely moving. The was like in the RAH, where the expert panel said after, all their chairs were vibrating, and so were mine. This work also has a large part for percussion, and they were totally tight and life like. That is what I am after, and essentially reject inefficient brute force approaches.

I fail to see how this design moves us forward in the least. To me it sounds like a real dead end. I would take a lot of persuasion to put out any hadr cash for it.

I would say because of the nature of the design, only reliable conclusions can come from free air measurement as well as in room ones. I say this, as I think your open air measurements could be satisfactory and in room responses exceedingly lumpy.

I await your measurements with interest as above.

 

[its phillip]

I wonder if Perlisten would send me a pair in exchange for my ULS-15s

 

[ryanosaur]

I wonder if Perlisten would send me a pair in exchange for my ULS-15s

Ah, optimism springs eternal!

 

[shadyJ]

That is right. I await the measurements with interest.

I can't believe that the design concept of this speaker has much merit. Worse I think your open air measurements will be totally misleading in terms of how this speaker would actually behave in a room.

First of all this speaker may be a sealed box, but it will not behave anything like a sealed box speaker as we have come to know them.

Since the speakers are out of phase, sure there will be a coupling. However both positive and negative pressures in the box will be cancelled apart from any non linearity between the divers. So the closed box model would not apply in any meaningful sense whatsoever. So essentially there will be NO restoring force from the box on the drivers. So the restoring force has to be provided almost entirely by the suspension of the drivers. So this is much more akin to the infinite baffle model and not the sealed model.

However there is a significant difference. In the classic IB model there is only forward radiation. The rear radiation is lost in the huge space behind the driver which should not connect with the room. So there is no cancellation. The system Q in these systems closely follows driver Q and restoring force is from the driver suspension entirely.

Now this speaker is a Dipole as the speakers are out of phase, and so side radiation will be cancelled. This has to be the radiation pattern.

View attachment 49619

Note the nulls either side of the speaker. However unlike a Quad ESL for instance, a sub is dealing with very large wave lengths, greater than the width of the cabinet by far. So front back cancellations will be far more significant I suspect. So no wonder they need such an enormous xmax. This I fear is likely to lead to deterioration over time, due to increased laxity of the suspension, having to provide the restoring force. This has long proved to be the achilles heel of IB designs.

I have the strong suspicion that free air measurements of this speaker may differ greatly from in room performance.

This seems to me an inherently highly inefficient design due to cancellations from the out of phase speaker design. I am highly sceptical that the non linearity of backward and forward motion, is going to be improved by the inherent coupling of the drivers in this design. My intuition is that the huge driver excursions required will negate that advantage and actually be worse, especially over time.

There is no way that this can be an efficient design, and has to be very much in the brute force category, which as I think you know, I abhor.

Good design always works with nature's forces, to create synergy and mechanical advantage, which enhances efficiency and reducing stress on mechanical parts.

I would actually wager pretty good money, that my TLs which do not require sub drivers, would outperform that design concept. The Proms started a week ago and there was a really good performance of the Poulenc organ concerto. Daniel Hyde let the voice of Jupiter really rip and the whole room really shook, with the drivers barely moving. The was like in the RAH, where the expert panel said after, all their chairs were vibrating, and so were mine. This work also has a large part for percussion, and they were totally tight and life like. That is what I am after, and essentially reject inefficient brute force approaches.

I fail to see how this design moves us forward in the least. To me it sounds like a real dead end. I would take a lot of persuasion to put out any hadr cash for it.

I would say because of the nature of the design, only reliable conclusions can come from free air measurement as well as in room ones. I say this, as I think your open air measurements could be satisfactory and in room responses exceedingly lumpy.

I await your measurements with interest as above.

The measurements are up. But I think you misunderstand the arrangement of the sub design. Yes, the drivers are wired in opposite phase, but they are not in opposite phase with respect to the enclosure, so there is no dipole cancellation pattern. One driver is facing outward and the other driver is facing inward. Acoustically, the behavior is basically a normal sealed sub, albeit one with extremely low distortion. The push-pull design probably does not lend itself to high efficiency, but who needs efficiency when you have 3,000 watts. No one buys a Porsche for the MPGs.

 

[TLS Guy]

The measurements are up. But I think you misunderstand the arrangement of the sub design. Yes, the drivers are wired in opposite phase, but they are not in opposite phase with respect to the enclosure, so there is no dipole cancellation pattern. One driver is facing outward and the other driver is facing inward. Acoustically, the behavior is basically a normal sealed sub, albeit one with extremely low distortion. The push-pull design probably does not lend itself to high efficiency, but who needs efficiency when you have 3,000 watts. No one buys a Porsche for the MPGs.

So is the does the inward facing driver have the magnet sticking out of the cabinet, or is it in a tunnel, so the whole of the inward facing speaker is in the cabinet, or is it an isobarik arrangement? We really need a diagram of this sub. Certainly the measurements looked like a standard sealed arrangement. Having a motor system and a suspension with a 30 mm xmax is quite a design achievement.

 

[NINaudio]

So is the does the inward facing driver have the magnet sticking out of the cabinet, or is it in a tunnel, so the whole of the inward facing speaker is in the cabinet, or is it an isobarik arrangement? We really need a diagram of this sub. Certainly the measurements looked like a standard sealed arrangement. Having a motor system and a suspension with a 30 mm xmax is quite a design achievement.

You can see the magnet system of the second woofer behind the grills in the main picture and there's also an exploded view and see through type drawing that shows that as well.

 

[NINaudio]

Also, on the products web page there is a better diagram that shows some of the bracing too:

https://www.perlistenaudio.com/products/d212s/

 

[TLS Guy]

Also, on the products web page there is a better diagram that shows some of the bracing too:

https://www.perlistenaudio.com/products/d212s/

I see that now. I found the original diagram very confusing. So the actual enclosure space is very small. So that compressive space is small enough that there will be rapid temperature oscillations, with heating on compression and cooling on release. In addition playing a loud movie you might get a very nasty surprise and generate a sonic boom. A deafening boom is certainly on the cards, for the changes in pressure powerful motor systems could create with such a small volume of air.

Bob Carver once told me he got the shock of his life when he was experimenting with a small powerful sealed sub, and generated a sonic boom from rapid pressure change.

 

[Sed]

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!

 

[Pogre]

This type of build is cool, but most people want the Drivers to add to output rather than simply improve distortions. Any kind of isobaric or push-pull design uses that extra driver to achieve different goals than SPL, so whether its a $50 Driver or a $400... you can see how that might add up.
Can you imagine a Funk or Harbottle Driver being doubled up like that?

I'm impressed that these guys went after this in such a way. It's a commitment to be certain!

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.

 

[highfigh]

Okay, the aluminum voice coil sounds interesting and the justification makes perfect sense to me. In fact, why don't more manufacturers use aluminum instead of copper for voice coils? It seems like you'd have nothing to lose and all to gain from my limited understanding.

Also, the push/pull configuration. Does that create negative pressure inside the box between the 2 drivers when they're in action? Is that what helps with linearity and control?

Some manufacturers do use Aluminum voice coils- mostly pro brands, for higher power handling.

Push pull affects the air inside of the box the same way a single driver does and it does minimize certain kinds of distortions- Jamo used this in their PP-3000 speakers from the mid-'80s. We sold a lot of that model but, unfortunately, most brands were using foam surrounds at the time and I doubt many are still in operation. I hate foam surrounds- too many ways for them to degrade.

 

[Pogre]

Push pull affects the air inside of the box the same way a single driver does

On steroids, lol.

 

[highfigh]

If I had known you guys were going there, I might have made the drive.....

 

[highfigh]

On steroids, lol.

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.

 

[jeffca]

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.

 

[highfigh]

This design reminds me of the M&K subwoofers from maybe 10? years ago. If I remember right they were well regarded and had many positive reviews. Nothing remotely as massive and powerful as this Perlisten but it have me wondering if any of those engineers have any input in this design because is really close in design and I don't know of any other current company using this design.

Read this, from their site-

The story

This is the story of a few discerning audiophiles with the same passion, who started a company with some of the best talent in the industry and tons of industry awards to prove it.

www.perlistenaudio.com