SP-32 Audio Transformer Equivalent & Substitute Parts

Part Overview

The SP-32 is an audio coupling transformer manufactured by Triad Magnetics, designed for audio frequency applications requiring impedance matching between 500 Ohms primary and 50 Ohms secondary. This through-hole mounted component operates across the 300Hz to 100kHz frequency range with a 3.16:1 turns ratio. The part is currently in active production status with 736 units in stock. Substitute parts are identified when equivalent electrical performance, mechanical compatibility, and operational parameters align within the specified tolerances for this transformer category.

Substiute Parts

SP-32

Triad MagneticsIn Stock: 796SP-32 Datasheet

Current PartRFQ

MET-39

TamuraIn Stock: 1760MET-39 Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the SP-32 is determined by strict alignment of the following electrical and mechanical parameters:

Primary Substitution Criteria:

• Turns ratio of 3.16:1 (Primary:Secondary)
• Primary impedance of 500 Ohms
• Secondary impedance of 50 Ohms
• Frequency range covering 300Hz to 100kHz minimum
• Frequency response of ±2dB or better
• Power level rating of 50mW or greater
• Through-hole mounting configuration
• PC pin termination style
• Physical dimensions compatible with 0.410" L × 0.310" W footprint and 0.465" maximum seated height

The MET-39 manufactured by Tamura meets all primary substitution criteria. Both components share identical impedance ratios, frequency response specifications, power ratings, and physical mounting characteristics. Differences in DC resistance, isolation voltage, operating temperature range, and packaging format are secondary considerations that do not preclude functional equivalence in audio coupling applications.

Parameter Comparison

Engineering Selection Recommendations

SP-32 Selection Criteria: The SP-32 is the primary choice when the application requires ROHS3 compliance, extended low-temperature operation down to -40°C, or higher isolation voltage specification of 1000VRMS. The SP-32 is actively produced with current inventory of 736 units.

MET-39 Selection Criteria: The MET-39 serves as a functional equivalent when ROHS3 compliance is not mandatory and operating temperature range of -20°C to 85°C is acceptable. The MET-39 offers higher inventory availability with 1,662 units in stock and is supplied in tube packaging. The MET-39 is actively produced and maintains identical electrical performance across all critical audio coupling parameters.

Compliance Considerations: Both parts maintain active product status and comply with applicable regulatory frameworks (ECCN: EAR99). Selection between SP-32 and MET-39 should be based on specific application requirements regarding isolation voltage, temperature range, and compliance certifications rather than functional audio coupling capability.

Frequently Asked Questions (FAQ)

Q: Can MET-39 replace SP-32 in all audio coupling applications?

A: MET-39 provides functional equivalence for audio coupling applications within the specified frequency range (300Hz ~ 100kHz) and power level (50mW). Both transformers deliver identical impedance matching (500:50 Ohms), turns ratio (3.16:1), and frequency response (±2dB). Selection depends on application-specific requirements for isolation voltage, operating temperature range, and compliance certifications.

Q: What is the difference in isolation voltage between SP-32 and MET-39?

A: SP-32 provides 1000VRMS isolation at 1 second, while MET-39 provides 500VRMS isolation at 30 seconds. Applications requiring higher isolation voltage must use SP-32.

Q: Are the physical dimensions identical between SP-32 and MET-39?

A: Physical dimensions are functionally identical. Both components measure 0.410" L × 0.310" W (approximately 10.4mm × 7.87mm) with maximum seated height of 0.465" (11.80mm). Both use through-hole mounting with PC pin termination, ensuring direct PCB compatibility.

Q: What is the operating temperature difference between these parts?

A: SP-32 operates from -40°C to 85°C, while MET-39 operates from -20°C to 85°C. Applications requiring operation below -20°C must use SP-32.

Q: How do the DC resistance values affect substitution?

A: Primary DC resistance differs slightly (SP-32: 60 Ohms vs. MET-39: 55 Ohms), while secondary DC resistance is identical (8 Ohms). The 5 Ohm difference in primary resistance is within acceptable tolerance for audio coupling applications and does not preclude functional equivalence.

Q: What packaging differences exist between SP-32 and MET-39?

A: SP-32 is supplied in bulk packaging, while MET-39 is supplied in tube packaging. This difference affects handling and storage procedures but does not impact electrical or mechanical performance.

Q: Are both parts RoHS compliant?

A: SP-32 is ROHS3 compliant, while MET-39 is RoHS compliant. Applications requiring ROHS3 certification must specify SP-32.