Mesa/Boogie Quad Preamp — Vintage All-Tube Rack Guitar Preamplifier — Circa 1989 — USA — Serial 01438

Reverb Condition: Good

Asking Price: $1,999.99 + Shipping — Offers Welcome

POWERED ON AND TESTED IN STORE

Offered is an original-era Mesa/Boogie Quad Preamp, handcrafted in Petaluma, California, USA. This professional rackmount tube guitar preamplifier combines two independently voiced channels, four selectable operating modes, dual five-band graphic equalizers, and built-in spring reverb.

The Quad was developed as part of Mesa/Boogie's professional rack amplification system and remains an important example of the company's late-1980s all-tube preamplifier design.

PRODUCTION YEAR AND IDENTIFICATION

- Manufacturer: Mesa/Boogie

- Model: Quad Preamp

- Rear serial label: 01438

- Production era: 1987–1990 original-generation Quad

- Estimated manufacturing year: Circa 1989

- Country: USA

- Manufacturing location: Petaluma, California

- Finish: Black

- Format: 19-inch rackmount, three rack spaces

Mesa's documented production chronology places the original Quad Preamp within September 1987 through August 1990, with the later FU-2A generation beginning in August 1990.

Serial 01438 is consistent with the original production generation. The exact manufacturing date has not been independently verified.

ORIGINAL MESA DESIGN

The Quad incorporates two independent all-tube preamplifier channels sharing a common instrument input.

Mesa's original operating instructions describe Channel 1 as closely related to the Mark IIC design and Channel 2 as closely related to the Mark III.

Channel 1 — Rhythm 1 / Lead 1

Designed for classic Mesa clean and lead voicings, with independent controls for:

- Volume

- Treble

- Bass

- Middle

- Master

- Lead Drive

- Lead Master

Additional pull-function tone shaping includes Bright, Shift, Deep, and Lead Bright functions as identified on the panel.

Channel 2 — Rhythm 2 / Lead 2

Voiced for a wider range of crunch, overdrive, and high-gain applications, with its own independent controls for:

- Volume

- Treble

- Bass

- Middle

- Master

- Lead Drive

- Lead Master

Channel 2 also incorporates selectable pull-function voicing adjustments.

The two channels provide four distinct operating modes, with separate gain structures and extensive analog tone control.

DUAL FIVE-BAND GRAPHIC EQUALIZERS

Each channel has a dedicated five-band graphic equalizer with the following factory-labeled frequencies:

- 80 Hz

- 240 Hz

- 750 Hz

- 2,200 Hz

- 6,600 Hz

These two equalizers provide independent frequency shaping for the corresponding channels.

Factory switching provisions allow the equalizers to be assigned and controlled through compatible external switching equipment.

Both five-band equalizer assemblies and their slider controls are present in the photographs.

SPRING REVERB

The Quad's original design incorporates an analog spring reverb system combining two reverb tanks of different sizes and decay characteristics.

This is an actual spring-based reverb circuit, not digital reverb modeling.

The front panel includes a Reverb control, with additional external provisions for reverb cancellation and boost.

The installed reverb components have not been separately inventoried for originality.

EXTERNAL SWITCHING

The original Quad provides multiple external switching connections.

The rear panel includes:

- Four mode-switching connections: Rhythm 1, Rhythm 2, Lead 1, and Lead 2

- Two graphic-EQ switching connections

- Reverb Cancel switching connection

- Reverb Boost switching connection

- Four-pin FU-2 footswitch connection

The FU-2 connection and rear switching jacks are visibly present.

The Quad can interface with compatible external MIDI-controlled switching equipment, but this should not be confused with a verified onboard programmable MIDI system.

No FU-2 footswitch, external MIDI controller, or footswitch cable is included.

REAR-PANEL AUDIO CONNECTIONS

The photographed rear panel includes:

Input

- One 1/4-inch instrument input

Main Outputs

- Channel A main output

- Channel B main output

Recording Outputs

- Channel A recording output

- Channel B recording output

The recording-output circuit was designed to provide a separately equalized direct signal suitable for recording applications.

Effects Loop

- Effects Send

- Return A

- Return B

- Line Level / Low Level selector

The original design allows interfacing with mono-send and dual-return effects configurations.

These connections are intended for integration with compatible guitar power amplifiers, effects processors, and professional rack systems.

TUBE DESIGN AND CONSTRUCTION

The Quad is an all-tube guitar preamplifier.

Published model references describe an eight-tube 12AX7-family preamplifier configuration.

The exact brands, production dates, and remaining service life of the installed tubes have not been independently established.

There is no verified record of recent retubing or internal restoration.

The enclosure is a black metal rackmount chassis with integral rack ears, extensive top ventilation, and an original-style Mesa/Boogie front-panel layout.

POWER AND ELECTRICAL DETAILS

- Rear factory marking: 117V AC

- Rear fuse marking: 1 1/4 A

- Integrated AC power cord

- Front power switch

- Front standby switch

- Power indicator

- Six mode/EQ indicator LEDs

The existing attached AC power cord is included with the unit.

The original manual identifies the FU-2 footswitch system as a means of selecting operating modes. During initial power-up, multiple mode/EQ indicator LEDs may illuminate before a mode is selected.

FUNCTIONAL CONDITION

POWERED ON AND TESTED IN STORE

The preamplifier has been powered on and tested.

Photographs document the illuminated front power indicator and mode/EQ indicator lights.

No specific functional defect has been reported.

The original FU-2 footswitch is not included. Comprehensive verification of every external switching combination and connection has not been separately documented.

This listing does not claim recent professional servicing, calibration, or restoration.

COSMETIC CONDITION

Reverb Condition: Good

This vintage unit shows visible cosmetic wear consistent with previous use and rack installation.

Photographed wear includes:

- Multiple scratches and scuffs on the upper metal cover

- Surface marks and finish wear on the side panels

- Wear around the rackmount brackets and mounting points

- Dust and general age-related surface marks

- Minor scratches and handling marks around the chassis edges

- Wear and markings visible on the underside

The front panel retains its Mesa/Boogie branding, original-style control layout, dual equalizer assemblies, and identifying labels.

Please inspect the photographs carefully for the complete cosmetic condition.

ORIGINALITY AND SERVICE HISTORY

This unit displays the external features associated with the original-generation Mesa/Boogie Quad Preamp.

However, the following have not been independently verified:

- Exact manufacturing date

- Originality of every internal component

- Previous repairs or modifications

- Tube replacement history

- Previous ownership history

- Recent professional service history

No claim of complete factory originality, recent restoration, or newly installed tubes is made.

INCLUDED IN SALE

- One Mesa/Boogie Quad Preamp, serial 01438

- Attached AC power cord

- Installed internal components and tubes

Not included: FU-2 footswitch, external controller, MIDI switching equipment, footswitch cables, rack case, or additional accessories.

This is an original-era American-made Mesa/Boogie Quad Preamp with four operating modes, independent channel equalization, extensive switching capability, and built-in spring reverb.

Its vintage construction, factory-designed features, photographed cosmetic condition, and reported testing status are disclosed above.

Price: $1,999.99 + Shipping — Offers Welcome

440 Instruments

Augusta, GA