Type 91E Integrated Amplifier

In 1936 Western Electric commissioned the 91A amplifier and manufactured, installed, and maintained these early sound systems. Thus introducing a burgeoning Hollywood movie industry and moviegoers worldwide to the magical, yet naturalistic wonder of high fidelity sound reproduction. The 91E continues the legacy of Western Electric sound.

The Western Electric Type 91E Integrated amplifier is a Class A, single-ended (SE) design for high fidelity audio reproduction. It has more than double the conventional output power of the Western Electric Type 300B tube. This innovation was made possible by patented SE circuit topology. The 91E is made for the Western Electric 300B, to provide listeners with the highest possible performance and quality.

Many years beyond the vacuum tube era, the 300B remains the triode of choice for serious music lovers worldwide. The 91E, with its patented steered current source technology (SCS), has the best possible design allowing the 300B to truly sing,  elevating the listener’s audio  experience along with unforgettable industrial design. The 91E is a showpiece that balances rugged retro features, like nickel-plated handles and an oversized attenuator knob, with stylish glass tube caging and an easy-to read LCD screen for an overall modern elegance.

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Features

Single-Ended (SE) Topology
Implemented with single-ended (SE) tube amplifier technology. This allows for the most authentic listening experience possible, compared to push-pull configurations.
Steered Current Source Technology (SCS)
Experience double the traditional output power with advanced SE circuit design. This new level of performance is reached by using a fully linear, steered current source controlled exclusively by the tube’s output voltage. Lush detail in the midrange and masterfully articulated upper and lower frequencies are revealed.
Logarithmic Attenuator
A logarithmic attenuator is used to mimic the response of human hearing. The attenuator consists of only discrete resistors in a ladder configuration that are switched in and out of circuit with relays to produce a logarithmic attenuation of the output signal.
Interchangeable Output Transformer Block
Common output transformers are large and excessive. The 91E has smaller, interchangeable transformer block add-ons that allow users to match loudspeaker impedance. The result? Lower hysteresis, lower distortion, and a black-background soundstage.
LCD Screen
A bright and easy-to-read colour display shows the selected input, attenuator level, VU meter, and system status messages. The display also shows settings which can be adjusted by the included remote control.
Remote Control
The included infrared remote control allows for quick adjustment of amplifier settings such as input levels, balance, and LCD screen dimming.
Six Audio Inputs
Connect up to six (6) source devices.
Auto-Bias
Microprocessors automatically bias the 300B tube complement each time the amplifier is powered on. No manual adjustment is necessary.
Wireless Connectivity
Connect a device to stream audio wirelessly. This is a convenient option for iOS and Android users.

Specifications

Phono MM Sensitivity (10W / 4Ω) 0.75mV
Phono MC Sensitivity (10W / 4Ω) 70μV
CD Sensitivity (10W / 4Ω) 0.27V
CD Input Impedance 20kΩ
Phono MM Input Impedance 47kΩ | | 100 pF
SNR MM (10W / 4Ω, input 5mV) 83 dB(A)
SNR MC (10W / 4Ω, input 0.5mV) 73 dB(A)
SNR CD (10W / 4Ω, input 0.5V) 101 dB(A)
CD Frequency Response 15 Hz – 32 kHz (-3 dB)
Phono Frequency Response 30 Hz – 20 kHz (RIAA within +/- 0.5 dB)
Headphone Output Impedance 100Ω
Output Power / 4Ω / THD 10% 2 x 20 watts
Output Power / 4Ω / THD 5% 2 x 16 watts
Output Power / 4Ω / THD 3% 2 x 14 watts
Output Power / 8Ω / THD 10% 2 x 20 watts
Output Power / 8Ω / THD 5% 2 x 16 watts
Output Power / 8Ω / THD 3% 2 x 14 watts
BT* Standard v4.2
BT Codecs BC, MP3, AAC, FastStream, APTX
BT Sample Rate (adaptive) Up to 96kHz / 16-bit
BT frequency response 20 Hz – 20 kHz
BT SNR 96dB
Weight 49lbs / 22.2 kg
Dimensions 18.9 x 15 x 11.1” / 48 x 38 x 28cm
Chassis Machined Aluminum
Colors Nickel, Gold, Black
Operating Voltage 100V / 115V / 230V / 50-60Hz / 150 W
Power Consumption (Operation / Standby) 10W / 0.3W
Operating Temperature (Indoor) 18-32° C / 64-89° F
Operating Altitude 2000m or less
Mains Fuse 2A slow-blow
Electron Tube Complement 1x Matched Pair WE 300B, 2x ECC81

91E Integrated Amplifier - Black or Champagne £16998 (inc VAT)
91E Integrated Amplifier - Nickel £18500 (inc VAT)

Transformer Block Add-On 4-ohm or 16-ohm option £1098 (inc VAT)

300B Electron Tube

What makes the Western Electric 300B Tube so popular?

The Western Electric 300B is known all around the world for its sound quality, the same specification, materials, and testing standards have been used for 86 years. When you see the Western Electric name on the base, you know it means quality.

The WE 33B sound is balanced, powerful and refined with superb bass from the lowest frequencies. The midrange has a beguiling beauty with seductive vocals and instruments placed accurately and dimensional in front of the listener. High frequencies are transparent, sweet, open. The air and space is quite extraordinary and the soundstage is beautifully rendered with exceptional width and depth.

The magic of the Western Electric 300B is in its directly heated, oxide-coated filament. Though this combination is by no means unique to the 300B, the filament’s coating is. This special coating not only improves the lifetime of each tube, but also supports the dynamics required for superior music reproduction.

All pairs and quad sets are computer-matched based on a range of performance characteristics. We capture this data during final inspection and use it to identify eligible pairs. Offering tubes that are as close to identical as possible ensures optimal music playback. A matched set of Western Electric 300B vacuum tubes will always give you superb optimum sound quality.

Features

Average Characteristics
(Ef = 5.0 volts, a.c., Eb = 300 volts and Ec = -61 volts)
Plate current 60 milliamperes
Amplification factor 3.85
Plate resistance 700 ohms
Grid to plate transconductance 5500 micromhos

Limiting Operating Conditions for Safe Operation
(Not simultaneous ratings)
Maximum plate voltage: 450 volts
Maximum plate dissipation: 40 watts
Maximum plate current of an average tube for fixed grid bias: 70 milliamperes
Maximum plate current for manually adjusted grid bias or self-biasing circuit: 100 milliamperes

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Specifications

Classification
Moderate power, filamentary triodes for Class-A service.

Application
Audio-frequency amplifier in positions where power outputs of approximately ten watts or less are required at relatively low plate voltages.

Dimensions
Dimensions, outline diagrams of the tubes and bases, and the arrangement of electrode connections to the base terminals are shown under features.

Base and Mounting
These vacuum tubes employ medium, four-pin thrust type bases suitable for use in Western Electric 143B.  The 300B tube has the bayonet pin so located that it may also be mounted in a Western Electric 100M, 115B, or similar socket. The tubes may be mounted in either a vertical or horizontal position. If mounted In a horizontal position, the plane of the filament should be vertical.

Average Direct Interelectrode Capacitances
Grid to plate 15 µµf.
Grid to filament 9 µµf.
Plate to filament 4.3 µµf.

Filament Rating
Filament voltage 5.0 volts, a.c. or d.c.
Nominal filament current 1.2 amperes

300B Vacuum Tube - Single £695
300B Vacuum Tube - Matched Pair £1495
300B Vacuum Tube - Matched Quad £3095