There are no surprises in the Red Rose Music R3's plot of impedance magnitude and phase against frequency (fig.1). The saddle in the magnitude trace at 46Hz indicates the tuning of the rear-facing port, the peak in the upper midrange is due to the crossover filters, and the rising impedance at ultrasonic frequencies is a result of the ribbon's inductance. The impedance drops below 4 ohms only in the lower midrange and in the mid-treble, and although the electrical phase angle occasionally reaches high values, this never coincides with low magnitude. Consequently,…
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This graph probably looks worse than it sounds, as the perceived in-room balance will also be strongly affected by the speaker's radiation pattern. The lateral dispersion is shown in fig.5 (actual responses) and fig.6 (the differences between the off-axis plots and the axial response). Although it's hard to see exactly what's going on these graphs, they do suggest that the reverberant field in a smallish room will have more energy in the presence region, which, together with the peak at the top of the woofer's passband, might compensate subjectively for the lack of on-axis energy in the same…
Manufacturer's Comment
Editor: We appreciate Michael Fremer's excellent review of the R3 ribbon speaker, and thank Stereophile for its consideration.
It is curious but true that if a piano is tuned in perfect fifths, the octaves will be out of tune. This required the development of the tempered scale. So much for logic in music.
Most companies tune speakers for flat response measurements. In addition to making measurements, my associates and I fine-tune Red Rose speaker models with music. We make recordings of classical, jazz, blues, and spoken-word artists, and optimize…
Sometimes tweaks take on a life of their own. Take the one of using Armor All to keep speaker surrounds from drying out, which you can read all about in the November 2001 "Fine Tunes No.41" I recently got another e-mail on the subject from Dan Mazza at Arizona Hi-Fi, who agrees with Mark Gdovin's objections to using Armor All. (Read Mark's comments on the entire issue in the readers' letters linked to "Fine Tunes No.41.").)
Dan has been, he informs, a member of an auto-racing crew for more than 25 years (for which I salute him), and has done some racing himself. He seems very aware of…
Few topics will get audiophiles into an argument more readily than a discussion of the relative merits of tubed and solid-state equipment. A poll on the Stereophile website showed 53% of respondents choosing solid-state as their preferred amplifier design, while 38% indicated a preference for tubes—the remainder choosing "other," which presumably means digital amplifiers. (There has been no corresponding survey regarding preamplifier designs.) Opinions tend toward the dogmatic, with one respondent declaring "solid-state is more accurate," another stating unequivocally that "tubes sound…
The amplification devices are MOSFETs, which many audiophiles think of as the solid-state equivalent of tubes. Khomenko considers this an oversimplification, but agrees that MOSFETs and tubes are similar in one important respect: both need to be driven by a source that has lots of current. He points out that there are many types of MOSFETs, just as there are many types of tubes. The MOSFETs used in the VK-40 were selected for their "soft" linear characteristics.
The VK-40's gain stage is biased at a very high 250mA, which, according to Khomenko, eliminates the need for a buffer and…
Allied with the dynamic quality was a high degree of resolution and transparency. This allowed me to hear not only the effects of system tweaks, but, more important, the subtle musical details that are an important part of the listening experience. I find that the best test of this characteristic is provided by highly familiar recordings, ones that, in most cases, I listen to only when I'm in "testing" mode. At 2:08 into track 3 of the first Chesky Jazz Sampler and Audiophile Test CD (JD37)—which, if it were an LP, I would have completely worn out by now—there is a cymbal that starts up 'way…
Sidebar 1: Specifications
Description: Solid-state preamplifier with optional phono stage. Inputs: 3 balanced (XLR), 2 unbalanced (RCA). Main outputs: 2 XLR. Tape output: 1 RCA. Maximum voltage gain: 20dB. Frequency response: 2Hz-150kHz, -3dB. Crosstalk: -80dB at 10kHz. Input impedance: 100k ohms. Output impedance: 200 ohms. Minimum amplifier input impedance: 10k ohms, 3k ohms with optional Six-Pack. S/N Ratio: 96dB unweighted. Distortion at 2V RMS output: 0.01%. Maximum output: 20V RMS. Optional VK-P20 phono module: Voltage gain: 58dB or 44dB, selectable.
Dimensions: 19" W by 5.75" H…
Sidebar 2: Associated Equipment
Analog source: Linn LP12 turntable (fully updated), Ittok tonearm, AudioQuest AQ7000nsx cartridge.
Digital sources: PS Audio Lambda II transport, Perpetual Technologies P-1A/P-3A digital processors, Balanced Audio Technology VK-D5SE CD player.
Preamplifier: Convergent Audio Technology SL-1 Ultimate.
Loudspeakers: Avantgarde Acoustic Uno 2.0.
Cables: Digital: Illuminati Orchid AES/EBU. I2S: Mystic Reference. Interconnect: Nordost Quattro Fil, Nirvana S-X. Speaker: Nirvana S-L, Nordost Valhalla, Nirvana S-L wiring harness for Avantgarde Uno 2.0.…
Sidebar 3: Measurements
All measurements of the BAT VK-40 were performed on serial number 040800072—the sample that had given RD some problems with the mono switch—with some spot checks on sample '71. No appreciable differences were noted. All tests of the line stage were done in full balanced mode (balanced input to balanced output), with some tests repeated for the unbalanced line input. The phono-stage measurements, of course, were performed using an unbalanced drive signal.
Starting with the preliminaries, the balanced input impedance was a very high 244k ohms, while the…