Phono input impedance is 47k ohms with the MM board, 470 ohms with the MC. Note that these gain figures include the XVII's line-stage gain.
No gain specs are provided for the phono boards, but the gain can be inferred from the specified input sensitivity: The MM board's sensitivity of 150mV referenced to 1V output translates to just over 50dB of gain the MC board's calculated gain is 64dB. Two phono boards are available: one high-gain type for low-output moving-coil cartridges, and one low-gain for moving-magnet pickups. This is augmented by a removable phono board soldered between the input jacks and the phono stage.
#Exposure x7 coupon Patch
The phono stage occupies a small patch of circuit board on the unit's right side. Line-stage input impedance is specified at a lowish 10k ohms.
Although this use is not recommended, the XVII can reportedly drive headphones.
#Exposure x7 coupon driver
The complementary class-A output driver can source a significant amount of current and drive impedances as low as 1k ohm. Each line-stage channel comprises eight bipolar transistors, about 20 resistors, a couple polystyrene caps, and a few electrolytic caps the last, unusually, are used as coupling caps. A tape output bufferwhich uses just a single pair of transistors per channeladds slightly to the parts population. The line stage occupies just two 1½" by 2¼" pieces of the large circuit board. The size of the power supply is surprising considering the minimalist circuitry it drives. (The XVII is the first Exposure preamp to include a power supply in the same chassis as the audio circuitry.) These rather high voltage rails assure a high input-overload margin. This regulated ☒4V also supplies the input to the cascaded phono-stage regulatorsa pair of Linear Technology 337/317 TO-220 deviceswhich then supply ☑8V to the phono section. A pair of large TO-3 devices supplies ☒4V to the line stage. These feed four regulation stages: two for the phono section and two for the line section. As with all Exposure products, the capacitors are custom-made. A 250VA custom-made toroidal transformer (5" in diameter by 2¾" deep) supplies a bridge rectifier and two electrolytic filter caps. The XVII's massive power transformer would look more at home in a power amplifier than in a preamp.
Exposure's power amps have unbalanced inputs on XLR jacks for connection to the XVII (footnote 1). They're included because Exposure believes XLR connectors sound better than RCAs. The XLR jacks are single-ended, with only pins 1 and 2 wired. The XVII's main output appears on a pair of RCA and XLR jacks in parallel. The phono and CD line inputs are both higher-quality jacks. The chassis rear holds five pairs of line-level inputs and one phono input, all on gold-plated RCA jacks. The austere front panel has two rotary switchesone source selector and one record-out selectorand volume-control and power rocker switches. The XVII looks identical to Exposure's integrated amplifiers. The XV virtually defined the concept of musicality in an affordable product would Exposure's more ambitious XVII preamp live up to the XV's reputation? I was intrigued by the XVII after reviewing Exposure's superb $1295 XV integrated amplifier (Vol.16 No.2). The less the preamp does to the signal, the better.īut are there great-sounding, full-function preamplifiers for under $1500? This question led me to the $1495 Exposure XVII preamp, which incorporates a phono stage with easily switchable moving-magnet and moving-coil phono boards. Conversely, if a preamp sounds great, it'll get out of the music's way, letting through to the amplifier and loudspeakers exactly what's coming from the source components. No matter how good your source components or your loudspeakers, if a preamp sounds poor, it will degrade the system's overall musical performance. Every source component must pass through the preamp, which imposes its sonic signature on the music. This is unfortunate, because the preamplifierthe heart of any audio systemexerts a large influence on the system's overall sound quality. Further, many inexpensive products don't deliver the musical goods it's the rare product that combines great sound with an affordable price. This situation leaves the LP aficionado with fewer choices for affordable preamps. Moreover, many manufacturers are omitting phono stages altogether, on the assumption that people don't listen to LPs anymore. There are plenty of great preamps on the market, but they tend to be expensive or line-stage onlyor expensive line stages. It's hard to find a good full-function preamp ( ie, one that includes a phono stage) at a reasonable price these days. Marshall's famous phrase, "What this country needs is a good five-cent cigar," should be modified for the 1990s to be "What this world needs is a good $1500 preamplifier."
0 kommentar(er)
