Sidebar 3: Confounding, Cables, and Room Acoustics
In designing an experiment, one of the essential requirements is the avoidance of confounding. If you want to determine the effect of a single variable, you must change only that variable, and keep everything else constant. If you change more than one variable (unless it's part of a more complexly designed, multivariable experiment), then any differences in outcome may be due not to the variable of interest, but to the other, confounded variables.
This concept is relevant not only to scientific research but to conclusions drawn…
Sidebar 4: Measurements
I used DRA Labs' MLSSA system and a calibrated DPA 4006 microphone to measure the Focal Aria 936's frequency response in the farfield, and an Earthworks QTC-40 for the nearfield responses. The Earthworks microphone has a small, ¼" capsule, and so presents minimal obstruction to air flow in the ports. For logistical reasons, I measured a different sample from those auditioned by Robert Deutsch. The speaker was bolted to its plinth for the measurements, so that the downward-firing port was the specified distance from the floor. All measurements were performed with…
It was spring. I was planting kale and cabbage, wearing bib overalls, and listening to Pigboy Crabshaw (aka Elvin Bishop) on my iPhone. My girlfriend, "bb," came out, and just stood there laughing. "What's this? American Gigolo: The Alabama Years?"
Now, please, don't start worrying about your newest Stereophile reviewer. I've owned my share of Julie London and Jennifer Warnes records, but these days I'm more into Hazel Dickens and Maybelle Carter. It's summertime, fish are jumpin', and that dirt-road American music is getting me high.
But wait! Before I go fishing and napping, I…
The Roksan K2 BT played this song perfectly—not too rough, not too soft, but just the way I needed it to be. These Columbia recordings were made between 1927 and 1930; I doubt anyone could record Johnson's guitar more vividly today, and the 1993 CD remastering was done with taste and restraint. The K2 BT played the attitude and vibrato of Johnson's slide guitar with a vibrant, satisfying realism. Carl Sagan chose "Dark Was the Night" to be included on the "Golden Record" carried by both Voyager space probes because "It properly encapsulated the essence of loneliness that mankind often faces…
Sidebar 1: Specifications
Description: Integrated amplifier with phono stage and Bluetooth/aptX input. Analog inputs: 1 line level, 1 moving-magnet phono, 1 BT, 1 Bypass. Audio outputs: 1 Speaker L & R, 1 Preamplifier, 1 Headphones. Power output: 140W into 8 ohms (21.5dBW), >250W into 4 ohms (>21dBW). Input sensitivity: 510mV. Damping factor: >110 (8 ohms). Voltage gain: 5.7dB (preamplifier), 31.6dB (power amplifier), 37.3dB overall (pre & power). Power requirements: 100–120V, 50/60Hz; 220–240V, 50/60Hz.
Dimensions: 16.8" (432mm) W by 3.5" (90mm) H by 14.8" (380mm) D…
Sidebar 2: Associated Equipment
Analog Sources: VPI Traveler turntable & tonearm, Thorens TD-124 turntable & SME 3009 II tonearm; Miyajima Spirit (mono), Ortofon 2M Black & 2M Red, Shure M44-78 cartridges.
Digital Sources: Puresound A-8000 CD player, Oppo DV-980H SACD/CD player, Line Magnetic LM 502CA DAC.
Preamplification: April Sound BB1, Blue Horizon BN:09-11-009, Sentec EQ11 phono stages; Audio Note S1, Intact Audio step-up transformers.
Integrated Amplifiers: Creek 4330, Line Magnetic LM518 IA, Rogue Audio Sphinx, Naim NAIT 5si.
Loudspeakers: DeVore…
Sidebar 3: Measurements
I measured the Roksan Kandy K2 BT using my Audio Precision SYS2722 system (see www.ap.com, and the January 2008 "As We See It"). Before performing any measurements on an amplifier, I run it for an hour with both channels operating at one-third its specified maximum power into 8 ohms. Like the earlier Kandy K2, reviewed by Art Dudley in May 2010, the K2 BT got very hot after 30 minutes, at which point I cut short the conditioning.
The first test I usually perform with an amplifier after this preconditioning period is to examine its behavior with squarewaves…
The duet may be the most challenging form of jazz. Both musicians are on, all the time; there's no place to coast or hide. In a sense, this can be liberating. Pianists, say, can switch from melody to harmony to extended improvisation without worrying about whether the sax or trumpet will get in the way. But they'd better have something interesting to say, or the experiment in freedom will soon turn lame. Ditto for bass players: they can run scales or arpeggios for a while, but if that's all they can do, they're exposed as one-dimensional.
Pianist Kenny Barron and bassist Dave Holland have…
The founder and until recently the long-term editor of The Absolute Sound, Harry Pearson (left above), has passed away. His protege Michael Fremer (right above) offers an appreciation here and Robert J. Reina, a long-term friend, is writing his own rememberance of HP in the February 2015 issue of Stereophile. (The January issue has already gone to press.)
Wednesday & Thursday, November 12&150;13, 5:30–9pm: North Carolina
Dealer Audio Advice will host two consecutive Music Matters events, with special guest Michael Fremer of Stereophile magazine and AnalogPlanet.com. The Wednesday evening event will take place at Audio Advice's Raleigh location (8621 Glenwood Avenue), while the Thursday night event will be held at the dealer's Pineville showroom in Charlotte (11409 Carolina Place Parkway, near Carolina Place Mall). Several manufacturer representatives, including Dave Gordon (Audio Research), Alex Brinkman (Ayre Acoustics), and Jett…
