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Product Archive

MS-275

MS-series amplifier with archived owner manual, commonly referenced in discussions around SoFAS-era platform combinations.

Category

Amplifier

Series

MS Series

Era

1992-1995 (archived FAQ/manual sources)

MS-275 amplifier photo — Archived MS275 product photo from Phoenix Gold FAQ MS/MPS page.

Specifications

Output Power (4 ohm @ 12.5/14.4V): 75/95 WRMS x2
Output Power (2 ohm @ 14.4V): 125 WRMS x2
Output Power (4 ohm bridged @ 14.4V): 280 WRMS x1
Frequency Response: +/-1dB from 20Hz to 20kHz
Signal to Noise Ratio: >100dB
Input Sensitivity: 200mV to 2V
Input Impedance: >30k ohms
Input Voltage Range: 10.5V to 15.0V
Power Supply Efficiency: >80%
Damping Factor: 250:1 (40Hz into 4 ohm, manual ref)
Bass EQ: 0 to +12dB @ 45Hz
Minimum Impedance: 2 ohm bridged / 1 ohm stereo
Dimensions: 8.5"L x 11.4"W x 2.4"H

Visual Identification Notes

Manual gallery includes original cover and control/spec interior pages.
Terminal-block and panel graphics should be photographed for model matching.
Document any aftermarket cosmetic modifications in gallery notes.

Known Issues

Capacitor aging and solder fatigue at thermal stress points.
Intermittent contacts from long-term storage oxidation.

Recommended Service Actions

Inspect board condition and prior service quality before recap plans.
Verify channel balance and idle behavior after component replacement.
Track all substitutions with fitment and temperature 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.

Related Forum Threads

Catalog scans and ad archive (contributor thread)
Crowdsourced scan quality standards and indexing conventions for source documentation.

Gallery

MS-275 amplifier photo — MS-275 amplifier photo
Archived MS275 product photo from Phoenix Gold FAQ MS/MPS page.

MS-275 manual cover — MS-275 manual cover
Owner-manual cover extracted from archived PDF for visual identification and layout reference.

MS-275 manual page 2 — MS-275 manual page 2
Manual interior page used as technical and historical reference material.

MS-275 manual page 3 — MS-275 manual page 3
Additional manual page for control labels, tables, and period styling details.

Historical Notes

MS-Series Manual Archive Baseline
The Phoenix Phorum manual archive includes original MS-series documentation for MS250, MS275, MS2125, and MS2250, while the archived Phoenix FAQ indicates a 1992-1995 MS/MPS production window.

Source-Backed Verification

MS-Series archived FAQ specs and timeline
Cross-checked
- The FAQ provides per-model output tables for MS250, MS275, MS2125, and MS2250.
- The page states MS/MPS production years as 1992-1995.
- The FAQ distinguishes MS as high-impedance-optimized and MPS as low-impedance-optimized designs.
Source: Archived Phoenix Gold FAQ - MS/MPS Amplifiers
Open source page
MS-Series models with archived owner manuals
Cross-checked
- Manual index lists MS250, MS275, MS2125, and MS2250 owner manuals.
- The same directory also includes MS TA documentation and MAC-200 reference material.
- Archive PDFs provide direct model-specific material for visual ID and technical page expansion.
Source: Phoenix Phorum Manual Archive - MS/MAC Amps
Open source page
MS275 bridged value discrepancy across archived FAQ pages
Imported - Needs Primary Verification
- MS/MPS page lists MS275 bridged output as 280 WRMS x1 at 14.4V (4 ohm bridged).
- MS Special page lists FAS2400's MS275 section as 260 WRMS x1 at 14.4V (4 ohm bridged).
- This archive keeps the discrepancy visible and marks the bridged value for revision check pending additional primary evidence.
Source: Archived Phoenix Gold FAQ - MS Special Edition
Open source page

Sources / Notes

Archived Phoenix Gold FAQ - MS/MPS Amplifiers
Primary source used for MS275 spec table values and product photo.
Open source
MS275 Owner Manual
Primary manual source used for TRI-LINEAR behavior and current-draw references.
Open source
MS-Series Manual Index
Directory listing confirms archived MS-series documentation.
Open source

Model Disclaimer Block

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