I used DRA Labs' MLSSA system and a calibrated DPA 4006 microphone to measure the Manger p1's frequency response in the farfield, and an Earthworks QTC-40 mike for the nearfield responses. When I picked up the Manger speakers from Herb Reichert, he told me that he suspected that the p1's sensitivity was lower than the specified 89dB/W/m. My estimate was indeed lower, at 85.6dB/2.83V/m. Manger specifies the impedance as 4 ohms, which would mean that the p1 is actually drawing 2W from the amplifier with a 2.83V signal. The solid trace in fig.1 shows that the…
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Manufacturer's Comment
I would like to thank Stereophile for this well-written and excellent review.
As a designer and manufacturer of a unique loudspeaker technology, it is satisfying to know that a magazine exists with a well-intentioned and competent editorial staff. In the case of our review, Herb Reichert perfectly describes his perception of the particular sound reproduction abilities of the Manger sound transducer, which is at the heart of all Manger loudspeakers. The research that led to the invention of the Manger sound transducer was all about a better transient…
I was less than thrilled by Editor-in-Chief Jim Austin's suggestion to review the solid-state Krell K-300i integrated amplifier ($7000, plus an additional $1000 for the optional DAC). I had recently reviewed another $7000 integrated amplifier, the quite different hybrid Aesthetix Mimas, and while I ended up liking the Mimas a whole lot, I felt decidedly lukewarm about having to recalibrate expectations for another integrated, especially one that costs far less than my reference Dan D'Agostino Progression monoblocks ($38,000/pair) and whose DAC option is a fraction of the price of my…
I began with Muddy Waters's "Good Morning Little Schoolgirl" from his 1964 album Folk Singer (24/192 MQA, Chess/Tidal). Timbres were virtually neutral with just a touch of inviting warmth, dimensionality was impressive, and the guitar's cleanly articulated dynamic nuances drew me in. The Krell K-300i sounded great.
I was equally enamored of the reproduction of mezzo-soprano Marianne Crebassa's rendition, with pianist Fazil Say, of Debussy's "La mer est plus belle ques les cathedrals," from their album Secrets (24/96 WAV/Erato 564483). The sound was smooth and inviting—I loved the warm…
Sidebar 1: Krell Designer Dave Goodman on iBias and Other Features
The K-300i uses modern techniques that we've implemented in the recent designs and upgrades we've issued since the split. First, it has a differential current-mode input stage that drives a fairly conventional output stage. Though we've done such designs before, I discovered that by fine-tuning parts of the gain stage I could significantly reduce distortion—specifically the second-harmonic component. The predominant characteristic is now the third harmonic, which we've found makes the K-300i sound much better.
In…
Sidebar 2: Specifications
Description: Solid-state integrated amplifier with iBias, class-AB output stage, and optional D/A module. Analog inputs: 2 balanced (XLR), 3 single-ended (RCA). Optional digital inputs: 1 Toslink optical; 1 S/PDIF coaxial; 2 HDMI (HDMI 2.0a, HDCP 2.2; supports DSD audio and 4K video); 1 USB-A (USB 2.0 host); 1 USB-B (USB 2.0 audio device); 1 Bluetooth with aptX. Outputs: 1 pair speaker outputs; 1 pair single-ended preamplifier outputs (RCA); 1 HDMI output; 1 12V trigger output. Output power: 150Wpc into 8 ohms (21.8dBW), 300Wpc into 4 ohms (21.8dBW). Voltage…
Sidebar 3: Associated Equipment
Digital sources: dCS Rossini DAC & Rossini Clock;
Mytek Brooklyn DAC+; Apple 2017 MacBook Pro computer with 2.8GHz Intel i7, SSD, 16GB RAM; Intel NUC7i7BNH with 8GB RAM, 128GB SSD running Roon; Linksys routers (2), Small Green Computer Systemoptique optical isolation bundle, TP-Link gigabit ethernet media converters plus multimode duplex fiber optic cable (2); Small Green Computer linear power supplies (4) & Small Green Computer 200W Linear Power Supply; external hard drives, SSD USB sticks, iPad Pro.
Power amplifiers: Dan D'Agostino Master…
Sidebar 4: Measurements
I measured the Krell K-300i using my Audio Precision SYS2722 system (see the January 2008 "As We See It"). I usually precondition amplifiers by running them at one- third power into 8 ohms for an hour. The Krell almost made it, turning itself off after 55 minutes, with the front-panel display showing the message "Over temperature left channel." The top panel over the heatsinks was hot, at 142.8°F (61.6°C), but cooler over the transformer at 113.1°F (45.1°C). This is a tough test for an amplifier with a class-AB output stage, as one-third power results in the…
My in-person introduction to Devialet's products was under auspicious circumstances. I was in Paris for what would be a month-long vacation; my wife was there to give some lectures, but I was free to roam the city, take pictures, practice my bad French, and enjoy the excellent food—the experience of a lifetime except that, a few days in, I was missing music. Still early in my visit, I wandered by the big Devialet retail store near the Paris Opera; it was closed but it gave me an idea. I soon had two Gold Phantom powered loudspeakers in our Paris studio apartment.
That was my hands-on…
Because the Expert Pro is such a versatile product—it's basically a music computer that incorporates everything except the music-data source at one end of the system and the loudspeakers at the other—you have to tell it what you want it to do. If you want to use a turntable, you need to set the analog inputs to phono and set the gain and loading parameters appropriate to your cartridge. If you want to use SAM to make loudspeaker-specific adjustments, you'll need to turn that on, choose your loudspeaker from a long list, and assign that function to a button on the remote control. (Because…