SP-29 Audio Transformer Equivalent & Substitute Parts

Part Overview

The SP-29 is a 10kCT:500CT audio coupling transformer manufactured by Triad Magnetics, designed for audio frequency applications with a 4.47:1 turns ratio. This through-hole component operates across the 300Hz to 100kHz frequency range with ±2dB frequency response and is rated for 50mW power level. The part is currently active in production with 1073 units in stock. Substitute parts are identified when equivalent electrical and mechanical parameters are available, enabling component selection flexibility for procurement, inventory management, or design optimization within the specified parameter constraints.

Substiute Parts

SP-29

Triad MagneticsIn Stock: 1179SP-29 Datasheet

Current PartRFQ

MET-17

TamuraIn Stock: 1589MET-17 Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the SP-29 is determined by strict equivalence across the following critical electrical and mechanical parameters:

Primary Substitution Criteria:

• Impedance matching: Primary 10kCT and Secondary 500CT
• Turns ratio: 4.47:1
• Frequency range: 300Hz ~ 100kHz minimum
• Frequency response: ±2dB
• Mounting type: Through Hole
• Termination style: PC Pin
• Physical dimensions: Compatible with 0.410" L x 0.310" W footprint and 0.465" maximum seated height

Secondary Compatibility Factors:

• DC resistance values within acceptable tolerance for circuit operation
• Power level rating sufficient for application requirements
• Operating temperature range coverage
• Regulatory compliance (RoHS, REACH, ECCN classification)

The MET-17 (Tamura) meets the primary electrical criteria and mechanical form factor requirements, enabling direct substitution in applications where the specified parameter set is sufficient.

Parameter Comparison

Engineering Selection Recommendations

SP-29 (Triad Magnetics) - Primary Selection:

• Wider operating temperature range (-40°C to 85°C) suitable for extended environmental conditions
• Higher isolation voltage rating (1000VRMS @ 1 Second) for applications requiring greater dielectric strength
• Higher power level rating (50mW) for increased signal handling capacity
• ROHS3 compliance status
• Bulk packaging for high-volume procurement

MET-17 (Tamura) - Substitute Selection:

• Meets core electrical specifications: 10kCT:500CT impedance, 4.47:1 turns ratio, 300Hz-100kHz frequency range
• Identical frequency response (±2dB) and secondary DC resistance (80Ohm)
• Compatible through-hole mounting and PC pin termination
• Physically equivalent form factor (0.409" x 0.310" x 0.465" max height)
• RoHS compliant
• Suitable for applications within -20°C to 85°C operating range and 40mW power requirements
• Tube packaging for smaller quantity orders

Selection Constraints:

• MET-17 is not suitable for applications requiring the full -40°C lower temperature limit
• MET-17 is not suitable for applications requiring 1000VRMS isolation voltage
• MET-17 is not suitable for applications requiring power levels exceeding 40mW
• Both parts are classified as EAR99 for export control purposes

Frequently Asked Questions (FAQ)

Q: Can MET-17 be used as a direct replacement for SP-29 in all applications?

A: No. MET-17 substitution is valid only when all of the following conditions are met: operating temperature range does not require below -20°C, isolation voltage requirement does not exceed 500VRMS, and power level does not exceed 40mW. For applications requiring the full SP-29 specifications, direct substitution is not appropriate.

Q: What are the critical electrical parameters that must match for substitution?

A: The following parameters must be equivalent: primary impedance (10kCT), secondary impedance (500CT), turns ratio (4.47:1), frequency range (300Hz-100kHz minimum), and frequency response (±2dB). These parameters define the transformer's core function in audio coupling applications.

Q: How do the DC resistance values affect substitution?

A: Primary DC resistance differs slightly (SP-29: 1.05kOhm vs. MET-17: 1kOhm), but both values are within acceptable tolerance for audio coupling transformer operation. Secondary DC resistance is identical (80Ohm) for both parts. These values affect circuit impedance and signal loss but do not prevent substitution when other parameters are equivalent.

Q: What is the significance of the different packaging formats?

A: SP-29 is supplied in bulk packaging, suitable for high-volume manufacturing and assembly operations. MET-17 is supplied in tube packaging, typically used for smaller quantity orders or component kitting. Packaging format does not affect electrical or mechanical compatibility but influences procurement strategy and inventory management.

Q: Are both parts RoHS compliant?

A: Yes. SP-29 is ROHS3 compliant, and MET-17 is RoHS compliant. Both parts meet current regulatory requirements for hazardous substance restrictions. Both are classified as EAR99 for export control and are REACH unaffected.

Q: What is the difference in isolation voltage rating between the two parts?

A: SP-29 is rated for 1000VRMS @ 1 Second isolation voltage, while MET-17 is rated for 500VRMS @ 30 Seconds. This difference reflects different manufacturing test conditions and dielectric strength capabilities. Applications requiring high-voltage isolation must use SP-29.

Q: Can MET-17 handle the same power levels as SP-29?

A: No. SP-29 is rated for 50mW power level, while MET-17 is rated for 40mW. For applications requiring power levels between 40mW and 50mW, SP-29 must be used. MET-17 is suitable only for applications at or below 40mW.