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Kuzma Air Line tonearm Manufacturer's Comment

Sidebar 3: Manufacturer's Comment

Editor: I was pleased to read in the August issue that MF believes that the Air Line tonearm could be "the finest tonearm ever built." MF raised, however, a few points that I would like to address:

"Theoretical problems" with porous-wall bearings... Air bearings are used worldwide by leading manufacturers of the most precise industrial machinery in conditions far more demanding than their uses in audio. In the last decade, porous bearings (acting as an infinite number of small holes), as opposed to the much smaller number of larger holes in…

Conrad-Johnson Premier Eleven power amplifier

I love being seduced. I'm shocked to learn that not everyone does. The very qualities in live music that excite and intoxicate me are denigrated by many audiophiles as "colorations." It would seem they prefer the lean, chilly sound that they've dubbed "accurate." While I concede that almost all of their preferred audio components have ever-more-extended high frequencies, I'm not certain that that's the same thing as having greater accuracy. It sounds to me—to use Stravinsky's description of electronic music—"spayed for overtone removal." The overtones that I miss are those stripped from the…

Conrad-Johnson Premier Eleven power amplifier Page 2

Tu-be or not tu-be
Intriguing? You bet! The Premier Eleven is chock-full of intrigue, and also of high-quality parts. Designed to be the entry-level amplifier of Conrad-Johnson's flagship Premier line, it's rated at 70Wpc. It uses two 6550 output tubes per channel in a push-pull configuration, two 5751s control the voltage amp, and a pair of 6CG7s are the phase inverter/output drivers. The amp's output stage is described as being ultralinear, and boasting unusually wide-bandwidth output transformers rated in excess of 100kHz. Additionally, I find it to be one of the most gorgeous jewels…

Conrad-Johnson Premier Eleven power amplifier Page 3

Speakers that would logically be paired with this amplifier, such as my reference Martin-Logan Aerius or the ProAc Response 1S, really shone when driven by the Conrad-Johnson. The sound—from top to bottom—was extremely well-integrated and coherent. Timbrally, this amplifier has no presence at all. It doesn't have a romantic tendency—the signature of so much tubed gear. Neither does it exhibit the hardness in the upper midrange and overtone region that distinguishes so many tubed products designed to not sound romantic.

In tandem with speakers that share its lack of coloration and that…

Conrad-Johnson Premier Eleven power amplifier Specifications

Sidebar 1: Specifications

Description: Tubed stereo power amplifier. Power rating: 70Wpc into 8 ohms/70Wpc into 4 ohms/70Wpc into 2 ohms (18.45dBW, 15.45dBW, 12.45dBW, respectively) Current capacity: not specified. Frequency response: 20Hz-20kHz, +0/-0.5dB. THD: <1%. IM distortion: <1% (conditions not stated). Input impedance: 100k ohms. S/N ratio: 96dB ref. rated power (weighting not stated). Sensitivity: 950mV.
Dimensions: 17.5" W by 7.25" H (with feet) by 15" D. Weight: 48 lbs.
Serial number of unit tested: 6001147.
Price: $3295. Approximate number of dealers: 70.
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Conrad-Johnson Premier Eleven power amplifier Measurements

Sidebar 2: Measurements

The Premier Eleven's input impedance measured 110k ohms. The output impedance was between 0.48 and 0.56 ohms, varying only slightly with changing frequency and load. This is good performance for a tube amplifier, and I would expect the Premier Eleven's performance with varying loudspeaker loads to be more consistent than those of many tube designs. The voltage gain into 8 ohms was 25.7dB. Its S/N ratio measured 84.2dB (L) and 82dB (R), and DC offset was unmeasurably low in both channels.

Fig.1 shows the frequency response of the Premier Eleven at 1W into 8…

Conrad-Johnson Premier Eleven power amplifier Measurements part 2

In the Conrad-Johnson's THD+noise vs frequency plot (fig.5), the distortion increases more than we normally see at the frequency extremes. Though such a characteristic is not uncommon in tube amplifiers, it's somewhat more pronounced in the Premier Eleven than in most others. The rise in the bottom end may result in a softened bass performance in some circumstances; the top-end rise will produce distortion components well above the audible range.

Fig.5 Conrad-Johnson Premier Eleven, THD+noise (%) vs frequency at (from top to bottom at 1kHz): 4W into 2 ohms, 2W into 4 ohms, and…

Conrad-Johnson Premier Eleven power amplifier Measurements part 3

Feeding a combined 19+20kHz signal into the Premier Eleven driving 8 ohms and doing another spectral analysis results in the data shown in fig.8. None of the artifacts in this figure is greater than 0.01%, and their level didn't increase into a 4 ohm load. This is superb performance for a tube amplifier. The THD+N vs level measurements in fig.9 show that the Premier Eleven gives its maximum output power and generally lowest distortion into a 4 ohm load. The actual clipping levels are shown in Table 1.

Fig.8 Conrad-Johnson Premier Eleven, HF intermodulation spectrum, DC-22kHz, 19…

Conrad-Johnson Premier Eleven power amplifier Sam's Space, February 1994

Sam's Space, February 1994

Sam Tellig wrote about the Premier Eleven in February 1994 (Vol.17 No.2):

The Premier Eleven is not a 300B amp, but what the heck—I have to fit it in somewhere.

Some months ago I was favorably impressed with the Conrad-Johnson MV-125, a 125Wpc stereo amp that retailed for $3995. I had borrowed the amp from Howie Mandel and thought it offered good tube-bang for the buck. What I liked most about it was the same thing Martin Colloms liked in his review (footnote 1): a sense of spaciousness, the presentation of the recorded acoustic. This was a big…

Conrad-Johnson Premier Eleven power amplifier Follow-up: the Eleven A

Follow-up: the Conrad-Johnson Premier Eleven A

A Follow-up by Wes Phillips appeared in August 1995 (Vol.18 No.8):

In my original review in October 1994 of Conrad-Johnson's Premier Eleven power amp, I waxed enthusiastic over what I felt to be a truly special product. Did I say waxed enthusiastic? I was so besotted that my review read like a love letter to the Muses—specifically Euterpe, Polyhymnia, and Terpsichore.

Tom Norton cast a more dispassionate eye on the unit's measured characteristics—which is the whole point of our specs section—and wondered why the amplifier…