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Perlisten Interview

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The following is an interview of Perlisten CEO and Co-founder Dan Roemer.

I see on the website the brief bios for Dan and Lars. Are there others deserving particular mention in association with the success of Perlisten?

Erik Wiederholtz, Stephen Mascenik and Peter Yang also are partners of Perlisten

The company timeline mentions a “high end manufacturing group.” Which manufacturing group is making Perlisten speakers?

Perlisten has its own manufacturing group near Dongguan City, China. Including transducers, crossovers, amplifiers, cabinets, painting, veneers, final assembly, and quality assurance.

When and how did Perlisten begin and what is the significance of the term perceptual in the name? What does that denote? What was the event that led to the formation of the company?

Perlisten = Perceptual Listening Experience. After all of the research hours, engineering, and manufacturing, what ultimately matters is enjoying the experience. The emotional connection to the art. We always want to keep this in perspective.

Please describe the target customer for Perlisten products.

I often describe audio reproduction as peeling layers back. Each layer reveals another level of performance and realism. This is our pursuit, and I see our customers as those who are very interested in seeking the highest levels of performance and enjoyment.

In regard to designing, what is Cosmol acoustic modeling? Please explain its advantages.

The technologies that Perlisten has developed are rather complex and, in fact, simply could not be realized just a few years ago. This is where the multi-physics modeling becomes an essential part of the development chain. We are able to consider new ideas and test them first in our models, then refine them to the point we are confident we can begin development. This is how we developed the DPC array incorporating multiple radiating surfaces in a complex 3D geometry. The benefit we achieved was a very unique way to control the wavefront. So the benefits are two-fold: 1) pursuing new ideas and 2) development time.

There is no description of the crossovers used inside Perlisten products. Please discuss the nature and parts caliber of Perlisten crossovers. Please use the S7 as an example.

The crossovers are a critical part of the whole speaker ‘array.’ Perlisten’s philosophy is to start with establishing the desired family of curves to deliver the sensitivity, bandwidth, power response, on- and off-axis directivity, etc., that we want —we’ve spent many years creating and establishing these targets. This requires the crossover to be used in somewhat of a non-traditional sense —overlapping bandwidths and varying slopes among other things. The result is a rather complex crossover, but very consistent and desirable results. We dictate 1% tolerance on the inductors and 2% on the remainder. We then pair match speakers to within 0.5dB. Air core inductors are used throughout the S7t. Metallized polypropylene film capacitors are used exclusively on the mid and tweeter networks, with metallized polyester on the woofers. Aluminum encased, non-inductive resistors are used throughout.

S7t woofer PCBA

S7t Mid/Tweeter Crossover PCBA

I believe that Dan Roemer said the software for the subwoofers is proprietary. Please discuss the development of the software for the subwoofers and what makes it more advantageous than a typical sub with standard controls.

Correct, the software was written by Stephen Mascenik. Because the amplifier and software are both developed by Perlisten, this allows us to control things unlike any other company that I am aware of. It all starts by developing intelligence into the amp —many, many criteria are monitored by the onboard processor (ARM Cortex-M3) and then we have spent years developing algorithms for how to handle this and adapt in real time. Some examples of this include signal input vs output, limiters, ac line voltage, amp temperature, etc.

The Datasheet for the D212s includes “multiple aluminum shorting rings” and “lightweight aluminum voice coil wire.” I am surprised to see aluminum used as a voice coil wire. Please explain how that can be in a premium subwoofer.

Every driver design is unique and designed from the ground up, but similar to the speakers it is the end goal of in-room performance where we start. Specifically, for the D212s a rather large +/-30mm linear excursion is required along with our target of very low moving mass and low inductance. This, as well as using 3 kilowatts. Managing all of this can be quite difficult —for example, simply increasing the voice coil windings will achieve large linear excursion, but the trade-off would be a very heavy mass and large inductance and possibly not meeting our power handling requirements. So in the end, utilizing aluminum wire (~1/3 the density of copper) allowed for higher linear travel and higher power handling (larger diameter wire for same resistance). Inductance is mitigated by the use of shorting rings. Then of course we optimize the motor – Bl(x), Le(x), Le(i), etc. to ensure linearity, stability and low distortion.

In Layman’s terms please explain what Klippel measurements are and their contribution to the design.

Klippel measurements are used to refine designs — both individual components and complete woofer/enclosure systems. The laser measurement system provides insight into various distortion mechanisms. As one example, at the engineering level this allows you to dial in the position of the voice coil for best performance (low distortion). The same can be said for the suspension components. Consider the design flow:

Initial designàFEA models àprototype samples àmeasurements (including Klippel) àrefine design and samples àverification measurements

By adding tools like Klippel and other measurements we are able to refine the design more and more (peeling the layers back).

The S7t has an open bottom with two generous ports. Explain Perlisten’s philosophy in regard to determining whether the ports should be left open or plugged.

Leaving the ports open will allow the S7t to play the lowest of frequencies.This is the desirable configuration for 2-channel full range without subwoofers. However, when using a sub(s) there maybe occasions where adding the plugs will be beneficial. The plugs create sealed box response and somewhat limit extreme LF output from the S7t. This may aid in blending a subwoofer to the mains.

Which company makes the carbon fiber woofers and mid/tweeters for Perlisten?

Our development partner was Textreme (now Composite Sound) located in Sweden but manufactured near Chicago, IL. We bring the formed diaphragms to our factory where the surrounds are attached and the final transducer assembly is made.

Composite Sound – Engineered Speaker Cones and Diaphragms – Composite Sound (composite-sound.com)???

Were grills placed on the midrange/tweeter drivers in order to protect them? Is there a reason related to sound quality why they are used? Can they be removed optionally?

The 28mm mids flanking the central tweeter dome are a part of the DPC array, which uses three transducers superimposed on a waveguide. In this case the grilles and their perforations are part of the waveguide geometry. This was a research project within the research project. In short, if the grilles are removed, the waveguide geometry is compromised.

The subwoofers use an unusual configuration of being in 90-degree opposition to each other. Please explain the reason that was chosen and the benefits.

The D212s uses a push-pull configuration where one driver is ‘flipped’ relative to the other. This creates a natural cancellation of asymmetries within the drivers (even after all the work to optimize the driver). In the case of the D212s we measured up to 10dB additional reduction of even-order harmonic distortion!

Please describe the DPC-Array. Evidently it is not the carbon fiber drivers, as the R Series also utilizes DPC-Array.

The DPC array is the combination of various transducers superimposed on a waveguide. This allows for specific horizontal and vertical dispersion control, higher power handling, lower distortion and wider useable bandwidth. This technology is patent pending. Our R-series speakers use the same technology with different transducers and geometry.

Is there an atypical sharing/overlap of the frequency spectrum by the mid/bass drivers and the mid-treble drivers? Is this extended from what would be expected of traditional driver integration, that is, does the operational band of these drivers overlap more than would be expected of more traditional designs?

Correct. This offers insight into how we control vertical dispersion to lower frequencies.

Is Textreme a brand name? What is its significance to the thin ply carbon fiber drivers?

Yes. TPCD allows the model response of the diaphragm to be optimized for each design (control of breakup modes). Additionally, Textreme typically is lighter than traditional carbon fiber diaphragms.

The website discusses a “timbre matching technique.” What is that timbre matching technique? What is involved in the timbre matching technique beyond construction of the drivers with Textreme and the waveguide?

Perlisten’s philosophy on timbre matching goes beyond simply using the same drivers. We look at the whole family of curves on axis and off. Vertical vs horizontal as well. Then once the desired result was achieved and confirmed by listening tests, we rolled this ‘sonic signature’ into the various sibling models. The first model was the S7t, then came the S5m, S4b, S5t, etc. The differences then between models are more related to sensitivity and LF extension.

Are the midrange carbon fiber drivers compression drivers? Wave guides are critical for compression drivers. Is that why they are placed into the waveguide?

Horn and waveguide essentially are describing the same thing —controlling the wavefront. The S7t combines multiple transducers with a waveguide without using compression. A compression driver/transducer is a completely separate category and comes with its own set of trade-offs.

When you were here for setup, I recall being told that HDF (High Density Fiberboard) is used for the cabinet. What else is done to the cabinet to dampen vibrations?

Yes, HDF throughout. We do several braces vertically and horizontally as well as adding layers of bitumen damping material to the interior surfaces in several locations.

Please explain the advantages of the combination of the midrange’s lower frequency crossover point as well as small size. One might think that the smaller size might produce more noticeable beaming, or the use of two drivers might cause comb effect. How do the twin midranges work without conflicting?

In fact, all 3x 28mm domes play together from approximately 1.1kHz (-10dB) where the wavelengths are large enough.The advantages are higher sensitivity, power handling, reduced thermal compression, and of course this allows for directivity control and beamforming. The beamforming is created by these drivers’ relative positioning as well as the amplitude and phase handled by the crossovers.

 

Copy editor: Dan Rubin

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