MET-37 Audio Transformer Equivalent & Substitute Parts

Part Overview

The MET-37 is an active audio transformer manufactured by Tamura, designed for audio coupling applications requiring 500 ohm primary to 600 ohm secondary impedance matching. This through-hole mounted component operates across the 300Hz to 100kHz frequency range with a 0.918:1 turns ratio and 50mW power handling capability. The part is RoHS compliant and currently in active production with 1120 units in stock. Substitute parts are identified when inventory constraints, lead time requirements, or specific application certifications necessitate alternative sourcing while maintaining equivalent electrical and mechanical performance.

Substiute Parts

MET-37

TamuraIn Stock: 1190MET-37 Datasheet

Current PartRFQ

SP-50

Triad MagneticsIn Stock: 1165SP-50 Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the MET-37 is determined by strict equivalence across the following critical parameters:

Primary Impedance: 500CT ohms (center-tapped configuration)

Secondary Impedance: 600 ohms

Frequency Range: 300Hz to 100kHz minimum coverage

Frequency Response: ±2dB flatness specification

Power Level: 50mW minimum rating

Mounting Configuration: Through-hole with PC pin termination

Physical Envelope: Maximum dimensions 0.409" L x 0.310" W x 0.465" H seated height

Isolation Voltage: Minimum 500VRMS capability

The SP-50 manufactured by Triad Magnetics qualifies as a substitute part based on matching impedance values, frequency range, frequency response, power level, mounting type, termination style, and physical dimensions. Variations in turns ratio (1:1.1 versus 0.918:1), DC resistance tolerances, isolation voltage rating (1000VRMS versus 500VRMS), and operating temperature range do not disqualify substitution when the primary impedance matching and frequency response characteristics are preserved.

Parameter Comparison

Engineering Selection Recommendations

MET-37 (Tamura): Select this part when Tamura component qualification is required by design specification or when inventory availability of 1120 units in stock supports immediate procurement. RoHS compliance and MSL 1 rating provide standard environmental handling. Active product status ensures continued availability.

SP-50 (Triad Magnetics): Select this part when extended operating temperature range (-40°C to 85°C versus -20°C to 85°C) is required for application deployment in cold environments. The 1000VRMS isolation voltage rating provides additional safety margin over the 500VRMS specification. ROHS3 compliance and Not Applicable MSL status indicate favorable environmental compliance. Inventory of 1149 units supports equivalent procurement lead times. Both parts carry EAR99 ECCN and 8504.31.4035 HTSUS classification.

The SP-50 demonstrates superior performance specifications in isolation voltage and operating temperature range while maintaining electrical equivalence in impedance matching, frequency response, and power handling. Selection between these parts should be based on specific application environmental requirements and manufacturer qualification constraints rather than functional performance differences.

Frequently Asked Questions (FAQ)

Q: Can SP-50 directly replace MET-37 in existing PCB designs?

A: Yes. Both parts share identical through-hole PC pin termination, equivalent physical dimensions (0.409" to 0.410" length difference is negligible), and matching seated height of 0.465". PCB footprints designed for MET-37 accommodate SP-50 without modification.

Q: What is the significance of the turns ratio difference (0.918:1 versus 1:1.1)?

A: The turns ratio variation reflects different impedance transformation approaches. Both achieve the required 500 ohm primary to 600 ohm secondary impedance matching. The impedance values, not the turns ratio, determine circuit compatibility. Applications designed for 500CT to 600 ohm impedance matching function identically with either part.

Q: Are there frequency response differences between MET-37 and SP-50?

A: No. Both parts specify ±2dB frequency response across the 300Hz to 100kHz operating range. Frequency response flatness is identical.

Q: Does the higher isolation voltage of SP-50 (1000VRMS) create compatibility issues?

A: No. Higher isolation voltage rating is a performance advantage. Applications designed for 500VRMS isolation operate safely with SP-50's 1000VRMS rating. The higher specification does not introduce incompatibility.

Q: What is the impact of DC resistance variations (MET-37: 65/95 ohm versus SP-50: 67/98 ohm)?

A: DC resistance variations of 2-3 ohms represent approximately 3% tolerance on primary and secondary windings. These variations fall within standard transformer manufacturing tolerances and do not affect circuit performance in audio coupling applications.

Q: Can SP-50 be used in applications requiring -20°C minimum operating temperature?

A: Yes. SP-50 specifies -40°C to 85°C operating range, which exceeds the -20°C to 85°C requirement of MET-37. SP-50 is suitable for all temperature conditions specified for MET-37.

Q: What packaging differences exist between MET-37 and SP-50?

A: MET-37 is supplied in tube packaging; SP-50 is supplied in bulk packaging. Both are through-hole components with identical termination style. Packaging format does not affect electrical or mechanical compatibility.

Q: Are both parts RoHS compliant?

A: Yes. MET-37 is RoHS Compliant; SP-50 is ROHS3 Compliant. Both meet RoHS environmental requirements. ROHS3 represents current RoHS directive compliance.