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It seemed logical to begin by comparing the ProLogue Three preamp with the CAT SL-1 Ultimate, keeping the Audiopax amps in the system. In evaluating preamps and power amps, I always do some matched-level comparisons, which in this case was complicated by the fact that the CAT preamp has a switched-resistor volume control with fairly large steps. What I did was to set the CAT's volume at a moderate level, measure the voltage at the amplifier speaker terminals when playing the 1000Hz tone on Stereophile's original Test CD (Stereophile STPH-002-2), and set the ProLogue Three's continuously…
Sidebar 1: Specifications
Prologue Three: Tube line-stage preamplifier. Tube complement: two 5AR4, two 12AX7, two 12AU7. Maximum gain: 12dB. Frequency response: 4Hz–110kHz, ±3dB. THD: <0.2% at 775mV RMS output. Signal/noise: >93dB(A) ref. 775mV. Input impedance: 110k ohms. Output impedance: 2800 ohms. Power consumption: 46W.
Weight: 23.5 lbs (10.7kg).
Serial Number Of Unit Reviewed: 05060314.
Price: $1395.
Prologue Seven: Tube monoblock power amplifier. Tube complement: four KT88, two 12AX7, two 12AU7. Power output: 70W (18.45dBW). Frequency response: 20Hz–85kHz, ±…
Sidebar 2: Associated Equipment
Digital Sources: PS Audio Lambda II CD transport, Perpetual Technologies/ModWright P-1A/P-3A digital processors, Monolithic Sound P3 power supply.
Preamplifier: Convergent Audio Technology SL-1 Ultimate.
Power Amplifier: Audiopax Model Eighty Eight Mk.II monoblocks.
Loudspeakers: Avantgarde Acoustic Uno 3.0, Silverline Audio Prelude, Fujitsu Eclipse TD-712z.
Cables: Digital: Mystic Reference I2S, Illuminati Orchid AES/EBU. Interconnect: Nordost Quattro Fils & Valhalla, AudioQuest Sky, PS Audio xStream Statement. Speaker: Nordost Valhalla.…
Sidebar 3: Measurements
The Prologue Three's maximum gain was to specification at 12.2dB, and the preamplifier preserved absolute polarity; ie, it was noninverting. The input impedance was usefully high, at around 100k ohms in the bass and midrange. It dropped, slightly but inconsequentially, to 77k ohms at 20kHz. The output impedance was also to specification in the midrange and treble at 2.7k ohms, which is higher than usual, but rose to a high figure of 11.5k ohms at 20Hz. This preamplifier really does need to be used with an amplifier having an input of 50k ohms or more if the bass…
As I write this, I am recuperating from four days of frenzy at the 1986 Winter CES in Las Vegas, Nevada. I am also pondering why I was so unexcited by most of what I saw and heard of the high-end exhibits; high-end audio may have reached a developmental plateau of sorts.
In my CES report elsewhere in this issue, I comment at length on what appears to be a lack of direction in audio—a lack of consensus about where we're going and how best to get there. While we all seem to strive for the same thing—the recreation of live music in the home—we view that ultimate goal from many different,…
Some reviews seem ill-fated from the get-go: samples break; systems go wrong; test equipment gives anomalous measurements; and at times the reviewer starts to doubt his or her ears when it seems impossible to get the component being reviewed to sound anywhere as good as reported by other writers. Such was the case with this review of the Celestion 3000. When Celestion's Barry Fox visited Santa Fe three days before Christmas 1989 with early samples of the speaker, we were dismayed to find that the ribbon of one of the pair was crinkled and immobile, apparently due to the extruded-aluminum…
The 45° corner mounting of the ribbon will also ensure a freedom from the "stereo hot seat" syndrome: a listener off to one side of the central seat will be more on the ribbon axis of the more distant speaker, thus receiving a stronger HF signal from it which will go some way toward compensating for the earlier arrival time of the sound from the nearer speaker. It also means that the speaker can be placed closer to a side wall than a speaker with the treble driver conventionally mounted on the front baffle, image-confusing HF reflections from the side wall being more suppressed with the…
The soundstaging was good, if not holographic, while instrumental and vocal images having any treble energy were thrust forward. The transition region between the woofer and ribbon was beautifully managed, however, there not being even a hint of discontinuity in the midrange. Low frequencies were powerful, with excellent extension noticeable on organ pedals, but overall I thought the 3000's bass register sounded a little disconnected from the rest of the range. This surprised me, as the SL600 and SL700 excel in the "tunefulness" of what bass they do have, by which I mean the way the low…
Levels of coloration in the low treble and midrange were low. My piano recording on the Stereophile Test CD reveals midrange problems on conventional two-way moving-coil speakers by some notes jumping out of the soundstage. The Celestion 3000 was remarkably clean in this respect, the Steinway tonality emerging unscathed. The flute and piano tracks on the Stereophile Test CD also reproduced as being extremely true to the sound of the original instruments, a slight accentuation of flute breath noise notwithstanding.
At higher frequencies there was some liveliness apparent in the low treble…
Sidebar 1: Specifications
Description: Two-way, sealed-box, stand-mounted loudspeaker. Drive-units: 21" by 0.5" aluminum-ribbon tweeter, 8" (200mm) polyolefin-cone woofer. Crossover frequency: 900Hz. Crossover slopes: 3rd-order, 18dB/octave, high- and low-pass. Frequency response: not specified. Low-frequency extension: –3dB at 66Hz, –6dB at 49Hz (both free-space measurements). Sensitivity: 86dB/2.83V/m. Nominal impedance: 4 ohms. Amplifier requirements: up to 100W program.
Dimensions: 25.6" (650mm) H by 13" W (330mm) by 11.8" (300mm) D. Internal volumes: 28 liters (woofer enclosure…