In 1998, PSB's Paul Barton revised the Alpha. The drive-units acquired magnetic shielding…
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The original PSB Alpha was reviewed for Stereophile by Jack English in July 1992 (Vol.15 No.7). A modest-looking two-way priced at just $199/pair, it combined a reflex-loaded 6.5" woofer using a plastic-doped paper cone with a 0.5" plastic-dome tweeter. JE summed up the Alpha by saying it "is simply one of the best buys in audio, providing a musically satisfying sound...a sensational audio bargain." It went on to become one of the best-selling audiophile speakers ever, with over 50,000 pairs sold.
The Alpha A/V's lows were not unmusical, the piano-toned bass guitar on Mary Chapin Carpenter's live "Stones in the Road" (from Party Doll, Columbia CK 68751) acquiring a pleasing thrum. And on well-recorded classical orchestral music---the Walter Legge-produced 1956 Kingsway Hall recording of Brahms's Symphony 1 with Klemperer has been spending much time in the Levinson '31.5 (EMI Classics CDM 5 67029 2, a 24-bit remastering)---the Alpha's slight bass overhang usefully warmed up the low end of the orchestra. But it appears that Paul Barton has loosened the low-frequency alignment of the…
Sidebar 1: Specifications
Description: Two-way stand-mounted, reflex-loaded loudspeaker. Drive-units: shielded 0.5" plastic-dome tweeter, magnetically shielded 6.5" coated-fiber-cone midrange/bass unit. Crossover frequency: 3kHz. Frequency response: 68Hz-21kHz, ±3dB on-axis; 68Hz-10kHz, 30 degrees off-axis. Sensitivity: 90dB/2.83V/1m. Impedance: 6 ohms nominal, 5 ohms minimal. Recommended power: 10-80W.
Dimensions: 12.75" (324mm) H by 7.75" (197mm) W by 9.75" (248mm) D. Cabinet volume: 0.39 cubic feet (11 liters). Weight: 11 lbs (5kg) each.
Serial numbers of units reviewed: 04110-…
Sidebar 2: Associated Equipment
Office System
Digital source: Meridian 500 CD transport, Panasonic A-120 CD/DVD player, Musical Fidelity X-24K 24/96 D/A processor.
Amplification: Yamaha @PET RP-U100 desktop receiver, Advent A300 receiver.
Cables: Canare interconnects, AudioQuest CV-4 loudspeaker cable.
Accessories: Pentium MMX 166MHz with Digital Audio Labs CardDeluxe soundcard connected to D/A via 75 ohm S/PDIF link, running Windows 98, WinAmp 2.5, and CoolEdit 2000.
Home system
Digital sources: Mark Levinson No.31.5 CD transport and No.30.6 D/A processor,…
Sidebar 3: Measurements
Despite its diminutive size, the Alpha A/V was quite sensitive, my B-weighted estimate coming in at 88.5dB/2.83V/1m. It is also a kind load for an amplifier or receiver to drive, its impedance (fig.1) dropping below 6 ohms only in the lower midrange and at the port-tuning frequency of 45Hz.
Fig.1 PSB Alpha A/V, electrical impedance (solid) and phase (dashed). (2 ohms/vertical div.)
The small wrinkles visible in the impedance plots at 200Hz and between 400 and 500Hz imply the presence of some kind of resonant behavior at these frequencies.…
But when you look at the curves more closely, there are other differences. The 1999 sample's upper-midrange peak is a little lower in frequency, which ties in with both the slight nasality and the forward upper mids I noted in my auditioning. The 1992 sample has a slight peak at 2.1kHz; in the newer version, this has moved up in frequency to 3.2kHz.
Fig.5 shows how the Alpha's response varies to the sides of the tweeter axis. (Just the differences are shown in this graph, which means that the on-axis response appears to be a straight line.) As very often is the case, the speaker's…
Nevertheless, when you look at the plot of the Alpha's spatially averaged in-room response (fig.7), lacks of energy can still be seen in the middle of the midrange and between 1.25kHz and 3kHz. In my auditioning, I picked up on this as an upper-midrange forwardness.
Fig.7 PSB Alpha A/V, spatially averaged, 1/3-octave, free-field response in JA's listening room.
In the time domain, the step response (fig.8) indicates that the Alpha's drive-units are connected with the same positive acoustic polarity, with the HF unit leading the woofer slightly in time. The discontinuity…
"J-10, tweakoman," began the e-mail from one of Stereophile's Web mavens and a contributor to "Industry Update," the estimable Barry Willis, "hockey pucks are the cure for what ails you."
I wondered where he wanted me to put 'em.
"Yes, plain old generic black-rubber hockey pucks. Forget the spiked feet under the speakers. Take 'em off and slip three or four hockey pucks under them instead. Haven't tried 'em as footers under other gear, but their density and vibration-damping qualities seem equal to or better than most expensive tweako materials. My local discount sporting-goods…
My first reaction to the Prima Luna Prologue One was based solely on looks: For $1095, I might not have been disappointed had it sounded no better than a Bose Wave Radio. Its casework straddles the breach between vintage and modern in a way that little else does, at any price. The dark gray-blue finish, hand-rubbed to a tactile gloss, wouldn't look out of place on an Alfa GTV (the new one, which resembles a drop of oil). And for the first time in my experience, a high-end audio manufacturer has figured out a way to make a protective tube cage easy to remove and replace: with banana plugs and…
Sidebar 1: Specifications
Description: Single-box line-level tube preamplifier and push-pull tube power amplifier. Tube complement: two each 12AX7A, 12AU7, EL34. Inputs: 4 single-ended. Output power: 35Wpc into 8 ohms (15.4dBW). Voltage gain: 20dB. Output impedance: 4 or 8 ohms. Frequency response: 20Hz–30kHz, ±0.5dB. Input impedance: 100k ohms. Input sensitivity: 300mV.
Dimensions: 11.5" W by 7.7" H by 15" D. Weight: 36 lbs.
Serial number of unit reviewed: 04031452.
Price: $1095. Approximate number of dealers: 1 (sold direct).
US distributor: Upscale Audio, 2504 Spring…