Solid State Power Amp Reviews

Big changes are afoot at Mytek. First up: The Mytek Brooklyn AMP+, the newest version of the compact, class-D Brooklyn AMP. The AMP+ is already in production.

In my 2018 review of the original Brooklyn AMP, I wrote that the class-D amplifier exuded "a consistent sense of truthfulness, striking resolution that was never analytical, spacious soundstages, superb dynamics, and some of the 'blackest' backgrounds I've ever heard...with the right recordings." I continued, "The AMP let me revel in its reproduction of the low end, with zero overhang or bloat, and profoundly impressive retrieval of micro- and macrodetail—but in doing all this, its touch was always light and never surgical."

Since then, Mytek president, founder, and chief designer Michal Jurewicz has been busy. Late last year, the company split from its longtime collaborator HEM, which operates the factory in Poland that has been making most Mytek products on contract for years. Because of the split, every Mytek product was discontinued. With the start of the pandemic, Jurewicz temporarily vacated the company's Greenpoint, Brooklyn, headquarters for sparsely populated upstate New York where, freed from everyday busy-ness, he designed new products and planned out the company's rerouted future. Plans were made to introduce whole new product lines and to update the company's existing products. First up, the Brooklyn AMP+ ($2495).

Why class-D?
I asked Jurewicz. "Class-D amplifier topology is based on one very sound principle," he responded via email. "If class-D topology is realized perfectly, the amplifier transfer function would be a straight line, meaning the amplifier will be perfectly linear with zero distortion. The challenge is to get the output squarewave as close to an ideal square as possible. When this is accomplished, the unit not only sounds better; it is also more efficient." Add to that efficiency light weight, far less heat dissipation, and plenty of power in a compact space, and it's easy to see why many audio manufacturers have entered the class-D amplifier market.

My first Stereophile review, in 2016, was of the Spec RPA-W7EX Real-Sound power amplifier, a class-D amp that measured badly but impressed Art Dudley and me. "This modest-looking amplifier was positively surgical in its retrieval of low-level information," I wrote, "yet it achieved the not-so-easy feat of doing so without sounding sterile or clinical."

In the five years since, many class-D amplifiers have been released, evidence that class-D sound has found favor as an alternative to heavy, conventional solid-state amps and often hot-running tube amps. The quality of class-D amplifiers has improved and grown more consistent.

On its exterior, Mytek's AMP+ looks no different from its predecessor, except for the plus sign in the logo. Its dimensions are the same—a "half-rack"–sized 8.5" wide × 1.74" high × 9.5" deep—as is the machine's faáade, its textured finish resembling polished alligator skin, in black or silver. Pushing a small, front-mounted button powers the amplifier; the "M" logo, backlit in your choice of colors, fades when it's powered down. Back-panel inputs and outputs are unchanged: one pair of balanced (XLR) and one pair of unbalanced (RCA) inputs, an IEC AC jack, and two pairs of binding posts for speaker cables. Nine tiny DIP switches enable conversion of the AMP+ from stereo to bridged mono; you can accomplish the same thing by downloading and installing Mytek's Control Panel app (which also lets you set the color of the front-panel backlight).

The AMP+ employs class-D modules from Danish firm Pascal A/S, modified by Mytek. The power specifications are impressive, especially considering the small package size: 250Wpc into 8 ohms, 300Wpc into 4 ohms, 400Wpc into 2 ohms. It's bridgeable to produce a mono amp that can put out 500W into 8 ohms and 600W into 4 ohms.

The original AMP included stick-on nubs for feet. The AMP+ has proper screw-on rubber feet.

Inside is where the main changes are. "We changed the MOSFET transistors of the AMP to be at least five times faster," Jurewicz told me. "The AMP+ has more detail, which results in a larger, deeper, more 3D soundstage. There's a faster clock, from 450kHz to now 653kHz. This allows us to move the output filter [higher], which translates as more air, a lighter top end. It's less analytical and makes the sound finer with a wider array of speakers. Class-D amplifiers will typically always have this filter, which is essentially a coil and a capacitor, on the output; that's supposed to turn the squarewave into regular sound, typically around 30kHz. When you move the filter up, it improves the sound because it affects the audio less." The output filter frequency in the AMP+ has been increased to close to 50kHz.

"Sometimes, when people listen to the AMP+ version," Jurewicz continued, "they say that the older Brooklyn AMP had this nice midrange, which is essentially a grunge produced by distortions, but it seems to be acceptable in the older model. The new model is cleaner, with a bigger soundstage and more detail. The AMP+ is more precise. I would look to achieve that midrange sweetness of the earlier AMP through other means, using other components that are in that direction. "The price of the Brooklyn AMP+ is the same as the original: $2495. Your Brooklyn AMP can be upgraded to AMP+ status for $500 at the company's Brooklyn headquarters. An upgraded AMP and a newly manufactured AMP+ are electronically and functionally identical, Jurewicz says (footnote 1).

Listening
I assessed the AMP+ against the AMP using Schiit Sol and Kuzma Stabi R turntables (the latter with the Kuzma 4Point arm and Koetsu Rosewood cartridge). I also used a Mytek Brooklyn DAC+/preamp, and Klipsch Forte III and RP-600M loudspeakers. A 6' pair of Shindo XLR-to-RCA interconnects connected the DAC/preamp (used as a phono preamp and for volume control) to the Mytek amps. Auditorium 23 speaker cables connected the AMP+ to either the Klipsch RP-600Ms or the Fortes.

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Footnote 1: Indeed, the sample under review is a former Brooklyn AMP, upgraded in Brooklyn to AMP+ status.