Интегральные усилители — Western Electric 91E

The Type No.91E is a valve integrated amplifier from Western Electric, designed and assembled in the USA at the company's Rossville Works in Rossville, Georgia, where it also makes 300B triodes by hand. Its name traces back to the 91A, which the Western Electric subsidiary ERPI commissioned in 1936 for the wall-mounted Type 500A cinema amplifier set, where a 300A tube produced at most 8 W to reproduce film soundtracks. US prices are USD 7,999 in champagne or black and USD 8,499 in nickel.

Key specs that matter

Rated output is 2 x 20 W into 4 or 8 ohm at 10% THD, falling to 2 x 16 W at 5% and 2 x 14 W at 3%. Six inputs are provided, including a phono stage with an MM/MC switch. MM sensitivity is 0.75 mV at 47 kOhm and 100 pF, MC sensitivity is 70 uV with a 1000 kOhm load that can be changed with plugs, RIAA accuracy stays within 0.5 dB from 30 Hz to 20 kHz, and signal-to-noise is 83 dB(A) for MM and 73 dB(A) for MC. The CD line input has 0.27 V sensitivity, 20 kOhm impedance, a 15 Hz to 32 kHz response at -3 dB and 101 dB(A) signal-to-noise. Bluetooth 4.2 handles SBC, MP3, AAC, FastStream and aptX at up to 96 kHz and 16 bit. The chassis measures 48 x 38 x 28 cm and weighs 22.2 kg, and consumption is 160 W running or 0.3 W in standby.

Engineering and use context

One matched pair of Western Electric 300B power triodes runs in a Class A3 parallel-feed single-ended circuit with no global feedback, driven by two ECC81 tubes. A patented steered constant current source power supply, which the company calls SCCS, lets the 300B deliver more than twice the output typical for this tube. Bias is set by a microprocessor, and the toroidal output transformers can be exchanged for impedance matching. A centred TFT screen shows input and volume, which is set by a digitally controlled optical encoder, and the IR receiver works with an Apple remote. The machined aluminium case has glass tube caging with etched labels and nickel-plated handles. USB and Ethernet ports are for service only, so the unit has no digital audio input for a computer. Mains settings cover 100, 115 and 230 V. Warranty is 90 days, extended to three years after registration.

Pairing

Turntables with moving magnet or moving coil cartridges connect directly to the phono stage, and phones or tablets stream over Bluetooth. A preamplifier output lets the 91E drive an external power amplifier, with a balanced XLR option at 600 ohm in that mode, while a power amplifier input accepts an outside preamp. A headphone output is also fitted.

Alternatives

Western Electric makes no other integrated amplifier, since its current amplifier range consists only of the 91E, the 97A monoblocks and the 116-C phono preamplifier.