Klyne SK-5A Preamplifier
Klyne Audio Arts' SK-5 preamplifier has been in production since about 1984. The latest version, the SK-5A, is of the minimal-frills school, having no tone controls and a minimum of inputs and tape recorder connections.
The SK-5A's outputs are unusual. Each channel has two output jacks of opposite polarity which can be used together, as a balanced-line output, or individually. With this system, one can directly bridge-drive a stereo power amp for higher output power even if the amp lacks internal bridging circuits. This would involve feeding one of the amplifier's inputs from the preamp's normal output and the other amp input from the corresponding inverted output, and connecting the speaker between the two "hot" output terminals of the amplifier. (One such bridged amp would be needed to drive each speaker.) The SK-5A can also be used to drive the two channels of a regular stereo power amp in opposite phase (with one speaker wired out of phase) to reduce peak demands on the amp's power supply. This would involve using the normal output for one channel and the inverted output for the other channel. Using both the normal and inverted outputs for each channel, the SK-5A can also directly drive a stereo power amp that has differential (balanced) inputs. In many cases, balanced operation is such an amplifier's best-sounding mode. With any of these connections, the polarity of both the normal and inverted outputs can be easily reversed, by means of a front-panel "Phase" switch, to get the best sonic results from various program materials.
In all, this is an interesting and useful system that may well show up in future designs.
Physically, the unit is quite attractive, with a platinum-gold anodized front panel and knobs and black-stained oak side panels. A black/gray front panel is also available at a slightly higher price.
The chassis construction is straightforward and simple. It consists of a piece of metal bent to form the sides and front subpanel, a separate bolted-on back panel, and top and bottom covers. A large, double-sided p.c. board takes up the whole interior of the unit. This is one of the most attractive p.c. boards I've seen. The parts layout is beautiful, and I especially liked the Klyne dragonfly logo on the board. First class!
Front-panel controls, from left to right, include a three-position source selector switch, a combination tape-monitor/mono switch (with mono mode available only in "Source" position), the balance and volume controls, and the aforementioned "Phase" switch (which mutes the output when set to its center position). The muting circuitry also operates for 30 S when the unit is first turned on. (The power switch is on the rear panel, as Klyne feels the unit should be left on all the time.) A two-color LED to the right of the phase switch lights up in red when the unit is first turned on or when it is placed In mute mode, and turns green when the turn-on delay ends or muting is disabled.
On the rear panel are Tiffany phono jacks for signal input and output connections, a gold-plated ground post, a small power-on/off rocker switch, and an a.c. input assembly. This assembly includes a line filter, a power fuse, a voltage selector switch, and a three-pin male socket for the a.c. power cord.
Construction and parts quality of this unit are first-rate.
Use and Listening Tests
Equipment used to evaluate the Klyne SK-5A consisted of an Oracle turntable fitted with a Well Tempered Arm and a Koetsu Black Goldline cartridge, a California Audio Labs Tempest CD player, Nakamichi 250 and Technics RS-1500 cassette decks, and Siefert Research Magnum III loudspeakers. An Audio Research SP11 preamp, slightly more than one year old, was used for some listening comparisons. The power amps used were a Sumo Polaris and an amplifier of my own design that has 845 triode tubes and develops 100 watts per channel.
A word about my current listening setup: Signal sources and preamps are placed along one wall of my living room. This equipment is connected to the power amplifiers by 30-foot lengths of Monster Cable Interlink Special cable, which has a capacitance of 1,500 pF per channel. The amplifiers are located near the speakers, which flank a corner fireplace, and are connected to them by short cables.
I frequently connect tape recorders, CD players, or phono preamps directly to the 30-foot cables with no intervening preamps. When doing this, I adjust volume at the amplifier end using a dual 50-kilohm external control with 1-meter interconnect cables going to the power amps. The sonic effect of this particular external volume control is detectable but generally quite tolerable.
When I first received the SK-5A, I hooked it up and listened casually for a number of days. I reacted quite favorably to the way it sounded in my system, as did other listeners. Operation of all the controls was flawless, with no clicks, pops, or surprises.
A month or two after running test measurements on the unit, I set it up again in my listening room to find out more about its sonic performance. Record reproduction was musically very satisfying. Definition, detail, space, and harmonic structure were very good, with low irritation levels. I first had the phono section set to moving-magnet mode. (If a phono stage is reasonably quiet, its MM input mode will work with MC cartridges, like the Koetsu, which can deliver 0.5 mV at 5 cm/S.) Gain was just adequate and noise was noticeable (too much), but the sound was as described above. To my amazement, when I set the SK-5A to MC mode with 22 dB of added gain, the sound was substantially the same, though with lower noise, of course. This is the first time I have found the sound as good when going through a unit's MC pre-preamp as when going straight into the MM phono stage. The noise levels in the moving-coil mode were low enough for me-I could hear the noise near the speakers when the gain was set to normal playing levels and the arm was off the record, but it did not intrude when records were playing.
The sound of my tape players was good through the SK-5A's line section. However, when playing CDs through the line section, I found the sound a little less open, darker, and harder than when using the line section of the SP11 or going direct from the CD player (via the 30-foot interconnect cables) into the volume control at the power amps. I can't account for this, as none of the other sources sounded that way when going through the line section.
I really like this preamp, especially the way it enhances my enjoyment of the music on phonograph records. It's well worth a serious audition.
