M808A Dual Channel Mircrophone & Instrument Preamplifier

The M808A is a sophisticated dual channel strip tube microphone/instrument/line level preamplifier designed to faithfully amplify and reproduce your microphone and Instrument’s signal, with rich and clean sonic output for professional recording systems. When pushed to its limits M808A produces excellent harmonic characteristics with rich overtones that resemble a warm and familiar vintage sound.

With switchable Pentode/Triode mode operation, various gain and unique harmonic colorations can be obtained. The state-of-the-art Saturation (THD) detecting circuit built in the M808A probes the total harmonic distortion of the mic input tube which allows the engineer to quickly verify on the fly the clean headroom before tube saturation occurs with a pilot light on the front panel. 

Although M808A has been designed from the ground up and has not been based on any traditional designs, the sonic characteristics of the preamp have been compared to tube British consoles of the 1960s. Part of the secret behind the big sound of the M808A is the Class A single-ended operation and its hand-wound audio transformers. 

Further sonic possibilities are available through the lossless active tube filters that consist of 4 useful HPF & LPF Frequencies with −6 dB per octave (−20 dB per decade) attenuation, making quick-cut decisions on program material a breeze.

Any high-quality condenser, dynamic, or ribbon microphones with output impedances ranging from 33Ω to 600Ω can be utilized successfully with excellent results. Numerous devices, including microphones, bass and electric guitars, instrument pickups, keyboards, organs, drum machines, line-level mixes, and much more can be routed to the M808A.

With the DIRECT/INSTRUMENT IN (DI) inputs, such instruments can be "directly" injected into the preamp, and a transformer-balanced signal will derive on the LINE OUT. Since the M808A is fully transformer-balanced from input to output, many balanced and unbalanced effect units can also be used through the insert points. Devices such as vintage tape echos, reverbs, equalizers, compressors, and even effect pedals can be used with excellent results.

Whether the device connected to the INSERTS is balanced or unbalanced, these signals will be transformer balanced at the LINE OUT jacks. The LINE IN feature of the M808A is ideal for keyboards, drum machines, and mix bus insertion and adds sonic coloration and make-up gain. This alternate LINE IN insertion point puts the signal right before the gain knob control into the 6350 tube and the rest of the chain and is an alternate way of bringing line-level signals to the preamp. Furthermore, Line level signals can also be patched to MIC IN input with the use of an external line-to-mic level attenuator to run the signal through the entire signal chain.

From the drawing board, the M808A has been designed with innovative features to produce the best sound quality and reliability possible. With a power supply with an auto-detectable line voltage feature operating from 86VAC to 265VAC, it will operate globally. The M808A features a fully regulated SMPS power supply for all its internal voltage nodes, contributing to extreme reliability, high power supply ripple rejection, low noise floor, and short circuit protection.

Our factory takes pride in producing high-quality audio transformers with low leakage inductance. Every microphone and output transformer in the M808A is designed and finished in-house, with each one individually wound, tested, and potted. All four audio transformers in the M808A have been potted in MuMetal shielding for the quietest operation.

Applications:

• Tracking

• Recording

• DI

• Sound Design

• Saturator

• Mix Bus

Key Features:

• Custom Designed And Manufactured Bakelite VU Meters With Traditional Ballistics

• Custom Designed Hand Wound Input & Output Transformers Hermetically Potted in MuMetal Casing

• Class A Operation Throughout The Signal Chain

• Up to 80dB Of Gain

• Channel Strip Design With MIC IN, LINE IN/OUT, DI, And Effect Inserts

• Low Noise Design Topology

• Custom Manufactured GR Style Bakelite Knobs From Original Moulds

• New Old Stock Matched Valves For Each Unit Manufactured

• Switchcraft® & Neutrik® Audio Connectors

• Active True Bypassable FILTER Section Featuring 4 Useful HPF & LPF Filter Frequencies of 50Hz, 150Hz, 5kHz, 2kHz @ −6 dB per octave (−20 dB per decade) Butterworth 1st order.

• Premium Grade 6350 ★★★★★ Output Tube

• Metal Film Resistors, Foil & Film Capacitors, Rubycon® & NIPPON Chemi-Con® Elcos Throughout The Unit

• All Through-hole Components And No SMDs

• Japanese Made TOCOS® Sealed Potentiometers

• Carling Toggle Switches

• Modular Design Throughout The Unit

• Fully Regulated & Adjustable SMPS Power Supply With Soft Start On HV Node

• High-Quality Sealed Japanese Relays With Gold Contacts For All Localized Signal Switching

• Individual Anti Pop Soft Start & Stop Phantom Power Switching & Indicator Lamp Per Channel

• Buffered & Isolated VU Meter Driver Circuit With Selectable +4dB Or +8dB Range

• Saturation THD Indicator Of The Input Valve

• 86V to 260VAC 50-60Hz Global Line Operation.

Specifications:

• MIC IN Input Impedance: (2KΩ) Accepts Microphones ranging from 33Ω - 600Ω

• MIC IN (Pentode Mode) Maximum Gain: Approximately 80dB

• MIC IN (Pentode Mode) Frequency Response: 10 Hz to 23 kHz ± 1dB @ 100Ω Source Impedance

• MIC IN (Triode Mode) Maximum Gain: Approximately 70dB


• MIC IN (Triode Mode) Frequency Response: 10 Hz to 20 kHz ± 1dB @ 100Ω Source Impedance

• LINE OUT Impedance: 600Ω or 150Ω @ +4dB Output

• INSERTS (SEND) Output Impedance: 250Ω

• INSERTS (Receive) Input Impedance: 100KΩ

• DI/INSTRUMENT Input Impedance: 1MΩ

• Signal to Noise Ratio: >75 dB, (A-weighted)

• Maximum Output Level for 1% THD: +10dB

• THD + Noise at +4 dB: 0.2% 2nd Harmonic Dominant (0.15% A-weighted)

• Crosstalk: -80dB Between Channels

• Power Requirements: 86V to 260VAC 50-60Hz For Global Line Operation.