MET-31 Audio Transformer 600CT:600CT Equivalent & Substitute Parts

Part Overview

The MET-31 is a 1:1 audio transformer manufactured by Tamura, designed for data/voice coupling applications. It features 600 ohm center-tapped impedance on both primary and secondary windings, operating across the 300Hz to 100kHz frequency range. The component is currently in active production status with 2400 pieces available in new original inventory. Audio transformers of this specification are essential in professional audio systems, telecommunications equipment, and signal conditioning circuits where impedance matching and galvanic isolation are required. Substitute parts become necessary when primary sourcing is unavailable, when alternative packaging formats are preferred, or when extended operating temperature ranges are required for specific applications.

Substiute Parts

MET-31

TamuraIn Stock: 2507MET-31 Datasheet

Current PartRFQ

SP-67

Triad MagneticsIn Stock: 1814SP-67 Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

The SP-67 manufactured by Triad Magnetics qualifies as a direct electrical and mechanical substitute for the MET-31 based on the following matching parameters:

Critical Matching Parameters:

• Turns Ratio: 1:1 (identical)
• Primary Impedance: 600CT (identical)
• Secondary Impedance: 600CT (identical)
• Frequency Range: 300Hz ~ 100kHz (identical)
• Frequency Response: ±2dB (identical)
• Power Level: 50mW (identical)
• Mounting Type: Through Hole (identical)
• Termination Style: PC Pin (identical)
• Physical Dimensions: 0.410" L x 0.310" W / 10.41mm x 7.87mm (functionally equivalent to 0.409" L x 0.310" W)
• Height - Seated (Max): 0.465" / 11.80mm (identical)

Acceptable Parameter Variations:

• DC Resistance - Primary: 72Ohm (SP-67) versus 70Ohm (MET-31) - within acceptable tolerance for audio coupling applications
• DC Resistance - Secondary: 92Ohm (SP-67) versus 95Ohm (MET-31) - within acceptable tolerance for audio coupling applications
• Operating Temperature: -40°C ~ 85°C (SP-67) provides extended lower temperature range compared to -20°C ~ 85°C (MET-31)
• Voltage - Isolation: 1000VRMS @ 1 Second (SP-67) versus 1000VRMS @ 30 Seconds (MET-31) - both meet isolation requirement
• RoHS Status: ROHS3 Compliant (SP-67) versus RoHS Compliant (MET-31) - both meet regulatory requirement

Parameter Comparison

Engineering Selection Recommendations

MET-31 Selection Criteria:

• Primary choice when Tamura sourcing is available and preferred
• Suitable for applications with operating temperature range of -20°C to 85°C
• RoHS Compliant status meets standard regulatory requirements
• Moisture Sensitivity Level 1 indicates no moisture sensitivity concerns
• Packaging in Tube format preferred for certain assembly processes

SP-67 Selection Criteria:

• Direct substitute when Triad Magnetics sourcing is available or preferred
• Extended operating temperature range (-40°C to 85°C) accommodates applications requiring lower temperature operation
• ROHS3 Compliant status meets current and future regulatory requirements
• Moisture Sensitivity Level Not Applicable indicates superior environmental stability
• Bulk packaging format may be preferred for high-volume production runs
• Functionally equivalent DC resistance values within acceptable engineering tolerances for audio coupling applications

Both components maintain identical electrical performance in the 300Hz to 100kHz frequency band with ±2dB frequency response and 50mW power handling. Both are through-hole mounted with PC pin termination, ensuring direct PCB compatibility. Selection between MET-31 and SP-67 is determined by supplier availability, packaging preference, and environmental operating requirements rather than electrical performance differences.

Frequently Asked Questions (FAQ)

Q: Can SP-67 be used as a direct replacement for MET-31 in existing designs?

A: Yes. The SP-67 is electrically and mechanically compatible with the MET-31. Both components feature identical 1:1 turns ratio, 600 ohm center-tapped impedance on primary and secondary windings, 300Hz to 100kHz frequency range, and ±2dB frequency response. Physical dimensions are functionally equivalent (0.410" vs 0.409" length difference is negligible for PCB layout). Both use through-hole PC pin termination. No circuit modifications are required.

Q: What are the DC resistance differences between MET-31 and SP-67?

A: MET-31 primary DCR is 70 ohms versus SP-67 at 72 ohms. MET-31 secondary DCR is 95 ohms versus SP-67 at 92 ohms. These 2-3 ohm variations are within acceptable tolerances for audio coupling transformer applications and do not affect circuit performance in standard signal conditioning and impedance matching applications.

Q: Does the operating temperature range difference affect substitution?

A: The SP-67 operating temperature range of -40°C to 85°C is an extended specification compared to MET-31 at -20°C to 85°C. This means SP-67 is suitable for all applications where MET-31 is used, plus additional applications requiring operation below -20°C. For applications operating within -20°C to 85°C, both components perform identically.

Q: Are there packaging differences between MET-31 and SP-67?

A: Yes. MET-31 is supplied in Tube packaging while SP-67 is supplied in Bulk packaging. This is a logistical consideration rather than a technical one. Both components are identical when installed on the PCB. Packaging selection depends on assembly process requirements and inventory management preferences.

Q: What is the significance of the isolation voltage test duration difference?

A: MET-31 specifies 1000VRMS isolation @ 30 seconds while SP-67 specifies 1000VRMS @ 1 second. Both meet the 1000VRMS isolation requirement. The SP-67 specification is more stringent (shorter test duration indicates higher dielectric strength). Both components provide equivalent galvanic isolation performance in field applications.

Q: Are both components RoHS compliant?

A: Yes. MET-31 is RoHS Compliant and SP-67 is ROHS3 Compliant. Both meet regulatory requirements. ROHS3 represents the current regulatory standard, making SP-67 compliant with both current and anticipated future requirements.

Q: What is the Moisture Sensitivity Level difference?

A: MET-31 has MSL 1 (Unlimited), indicating no moisture sensitivity. SP-67 has MSL Not Applicable, also indicating no moisture sensitivity concerns. Both components are equally suitable for standard storage and handling conditions without special moisture control requirements.

Q: Can these transformers be used interchangeably in audio coupling applications?

A: Yes. Both MET-31 and SP-67 are specified for audio coupling in the 300Hz to 100kHz frequency range with identical ±2dB frequency response and 50mW power handling. They are functionally interchangeable in professional audio systems, telecommunications equipment, and signal conditioning circuits requiring 600 ohm impedance matching and galvanic isolation.