Предусилители — Cary Audio SLP-98

The SLP-98 is a hand-built, hand-wired vacuum tube preamplifier from Cary Audio of North Carolina, built as two boxes - an audio chassis and an outboard supply - with remote volume control. Cary offers it in two forms - the SLP-98P with an onboard moving magnet phono section and the SLP-98L, which keeps only the line stage. The circuit runs in Class A with triodes and uses no global feedback.

Key specs that matter

Five inputs are fitted, four at line level plus one for a moving magnet cartridge on the P version. Line gain is 20 dB and the phono section adds 43 dB. Input impedance is 50,000 ohms on the line inputs and 47,000 ohms on the phono input, while output impedance is 440 ohms. Rated output is 2 V, with a ceiling of 12 V. Cary lists a frequency response of 5 Hz to 163,000 Hz and noise and hum at 88 dB below full output. The main chassis measures about 127 mm high, 318 mm wide and 305 mm deep, and the pair of boxes weighs 10 kg together.

Engineering and use context

Four 6SN7 octal double triodes form the line stage. In the phono section two 12AX7 tubes provide gain and two 12AU7 tubes act as buffers, so the vinyl path stays entirely in valves. Moving the transformer to its own enclosure keeps its field away from the low-level phono circuitry, and that external unit uses an EI laminate transformer rated at a 200% duty cycle with four 560 uF capacitors rated at 400 VDC for reservoir storage. Resistors are 1% metal film types and the coupling capacitors are polypropylene film with hand-soldered copper terminals. Mains input is switchable for 117 or 234 VAC at 50 or 60 Hz, and the unit draws 44 W in use. Cary quotes a three minute warm-up after switch-on and about 100 hours of running before the parts settle. Factory upgrade options include Mundorf or Jensen capacitors and Lundahl step-up transformers for moving coil cartridges. The chassis is anthracite black with a silver or black faceplate.

Pairing

The moderate output impedance and rated level suit most solid-state or valve power amplifiers with input impedances well above 10,000 ohms, and the high output ceiling leaves headroom for insensitive amplifiers. Cary's own stereo and mono power amplifiers are the obvious partners. The phono input is set up for moving magnet cartridges, so a low output moving coil design needs the optional Lundahl transformers or an external step-up.

Alternatives

The Cary Audio SLP-05 is the brand's other valve preamplifier, with eight 6SN7 tubes, balanced inputs and outputs, and a 5AR4 rectified external supply.