Product Archive

MQ-430

Four-channel TRI-LINEAR "High Definition" Phoenix Gold amplifier with a PWM MOS-FET switching supply and Triple-Darlington output stage, prized for sound quality rather than raw power. Best known today as the amplifier section reused in the limited-edition FAS-2300 (Frank Amp'n Stein).

Specifications

Channels: 4 (bridgeable; TRI-LINEAR simultaneous stereo + bridged mono)
Output Power (4 ohm @ 12V DC, 4-ch driven): 30 WRMS x4
Output Power (2 ohm @ 12V DC, 4-ch driven): 60 WRMS x4
Output Power (4 ohm bridged, 2-ch): 100 WRMS x2
THD at Rated Power (4 ohm): 0.01%
SMPTE IM (4 ohm): 0.05%
DIM (4 ohm): 0.07%
Frequency Response: 15Hz to 20kHz +/-1dB
Signal to Noise Ratio: >100dB (20Hz to 20kHz)
Input Sensitivity: 200mV to 2V
Load Impedance: 2 to 16 ohms
Input Impedance: 10k ohms
Idle Current: 2 Amps
Current Consumption (full power hard clip): 16A (4 ohm stereo) / 32A (2 ohm stereo) / 35A (2 ohm stereo, 4 ohm mono)
Power Supply Efficiency: >80%
Damping Factor (20Hz to 10kHz): 1000:1
Adjustable Bass EQ: 0 to +12dB @ 40Hz
Voltage Range: 10.2 to 15.5V DC
Dimensions: 11"L x 11.4"W x 2.4"H

Visual Identification Notes

Front-of-panel branding reads "MQ-430 Power Amplifier" with the Phoenix Gold logo (see manual cover).
End panel carries GAIN and BASS controls per pair, a STR/BRDG output switch, a floating/common ground switch, and ON / THERMAL / OVERLOAD LEDs (manual page 3).
Manual specifies an 11"-long chassis; confirm board revision marking (REV-B and REV-C boards are both documented by the community).
Optically isolated design with a master/slave 3.5mm "sync" jack for multi-amp installs.

Known Issues

Aging electrolytic capacitors and oxidized connection points typical of the era.
Community reports of low perceived output on some units; gain-stage and resistor values are commonly inspected before recap.
Condition varies widely due to mixed service history across surviving units.

Recommended Service Actions

Start with a controlled, current-monitored power-up before any load testing.
Verify supply rails and per-channel symmetry; an oscilloscope is recommended for gain-stage checks.
Log every replaced component with sourcing and measurement notes.

Parts List

Main power reservoir capacitor (4700uF / 50V class)
Original: 4700uF 50V radial electrolytic (legacy OEM variant)
Replacement: 105C low-ESR radial capacitor, matched lead spacing
Verification: Community Verified
Dual op-amp for preamp / crossover stage
Original: Legacy dual DIP-8 op-amp (marking varies by production run)
Replacement: Low-noise audio op-amp DIP-8
Verification: Proposed

DigiKey Recommendations

4700uF 50V low-ESR radial capacitor
DigiKey: P12345-ND
Placeholder DigiKey reference. Confirm ripple current, lead spacing, and can diameter against board footprint before finalizing.
Open DigiKey reference
Audio-grade dual op-amp replacement
DigiKey: P23456-ND
Placeholder DigiKey reference. Verify stability and compensation in original circuit before bulk install.
Open DigiKey reference

Related Repair Guides

Signal-path noise diagnosis (generic workflow)
Template process for hum, hiss, and channel imbalance root-cause analysis before replacing semiconductors.

Gallery

MQ-430 owner's manual cover
Owner's manual cover - MQ-430 Power Amplifier (Phoenix Gold, Portland, OR).

MQ-430 features and specifications
Features and full specification page: TRI-LINEAR output, Triple-Darlington stage, power ratings, THD/IM figures, current draw, and dimensions.

MQ-430 end-panel controls
End-panel diagram: per-pair gain and bass controls, STR/BRDG output switch, floating/common ground switch, and ON / thermal / overload LEDs.

MQ-430 installation - location and mounting
Installation guidance: mounting location, orientation cautions, clearance, and mounting-template notes.

MQ-430 electrical installation
Electrical installation: battery ground, fuse block, power and speaker wiring, soldering technique, and LED meanings.

MQ-430 system design and 6dB crossover table
System design notes and a 6dB/octave passive-crossover component-value table with high-pass / low-pass filter diagrams.

MQ-430 12dB and 18dB crossover tables
12dB and 18dB per-octave passive-crossover component-value tables with corresponding filter diagrams.

MQ-430 system wiring diagrams 1-2
System wiring diagrams: System 1 (stereo speakers with subwoofer) and System 2 (TRI-LINEAR output).

MQ-430 system wiring diagrams 3-4
System wiring diagrams: System 3 and System 4 (TRI-LINEAR output with bandpass and isobaric examples).

MQ-430 adjustments
Adjustment procedure: input-sensitivity / gain setting, bass-EQ usage, and output-mode setup.

MQ-430 master/slave connection
Master/slave "sync" connection guidance for multi-amplifier installs and the amplifier terminal diagram.

Historical Notes

MQ-430 Platform and FAS-2300 Reuse
The MQ-430 was a four-channel, sound-quality-focused amplifier from the early Phoenix Gold lineup. Secondary history describes it as relatively low in popularity, which left roughly 100 unused MQ-430 boards; these were paired with the MS-2125 to build the limited-edition FAS-2300 (Frank Amp'n Stein) in 1992. Per-channel output values are preserved in the archived FAQ.
Early Phoenix Gold and M-Series Emergence
Archived Phoenix FAQ material lists M-series output tables and identifies a 1992-1995 production window, while secondary history notes describe the broader late-1980s to early-1990s brand ramp.

Source-Backed Verification

MQ-430 specifications from owner manual and archived FAQ
Cross-checked
- The owner manual rates the MQ-430 at 30 WRMS x4 (4 ohm) and 60 WRMS x4 (2 ohm) with four channels driven at 12V DC, and 100 WRMS x2 bridged into 4 ohms.
- The manual also lists 0.01% THD, >100dB S/N, 15Hz-20kHz +/-1dB, 1000:1 damping factor, 10.2-15.5V DC range, and 11"L x 11.4"W x 2.4"H dimensions.
- The archived MS Special FAQ lists higher figures (30/50 WRMS x4 at 12.5/14.4V and 90 WRMS x4 at 2 ohm/14.4V); the difference is explained by the FAQ's higher test voltages versus the manual's 12V DC rating.
- The manual describes a TRI-LINEAR output (simultaneous stereo + bridged mono), a PWM MOS-FET switching supply, a Triple-Darlington output stage, and a gold-plated G10 board.
Source: MQ430 Owner Manual (archived PDF)
Open source page

Sources / Notes

MQ430 Owner Manual (archived PDF)
Primary owner-manual source for full specifications, features, controls, and wiring diagrams.
Open source
Archived Phoenix Gold FAQ - MS Special Edition
Secondary archived source listing MQ430 output values (at higher test voltages) within the FAS2300 section.
Open source
MQ Amps Manual Index
Directory listing confirms archived MQ430 documentation.
Open source

Model Disclaimer Block

Repair information is provided at user's own risk. Verify all measurements and polarity before power-up.