1、 MIL-PRF-25670B INCH-POUNDw/AMENDMENT 2 6 March 2006 SUPERSEDING prodrequiestabliin closperecommecompldocumentAMSC N/A Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHSMIL-PRF-25670B AMENDMENT 1 19 JULY 2002 PERFORMANCE SPECIFICATION EARPHONE ELEMENTS, GEN
2、ERAL SPECIFICATION FOR This specification is approved for use by all Departments and Agencies of the Department of Defense. 1. SCOPE 1.1 Scope. This specification covers the general requirements for earphone elements. These are ucts, which have screw type terminals and are used in communications hea
3、dsets for applications ring communication within high-noise conditions at either ground-level or altitude. These parts meet shed United States Air Force safety standards (see 6.1) for signal-generating equipment mounted se-proximity to the human ear. 1.2 Classification. Earphone elements are of the
4、following types, as specified (see 6.2). 1.2.1 Types. The types of earphone elements are as follows: MIL-PRF-25670/1 Medium Impedance (22 ohms) - (H-136/AIC), Ground Level MIL-PRF-25670/2 Low Impedance (19 ohms) - (H-143/AIC), High- and Low-Altitude - (H-143A/AIC), Low-Altitude, Immersible MIL-PRF-2
5、5670/5 High Impedance (1,000 ohms) - (M25670/5-01), Ground-Level, Immersible 2. APPLICABLE DOCUMENTS 2.1 General. The documents listed in this section are specified in sections 3, 4, or 5 of this cification. This section does not include documents cited in other sections of this specification or nde
6、d for additional information or as examples. While every effort has been made to ensure the eteness of this list, document users are cautioned that they must meet all specified requirements s cited in sections 3, 4, or 5 of this specification, whether or not they are listed. Comments, suggestions, o
7、r questions on this document should be addressed to: Defense Supply Center, Columbus, Attn: VAI, P.O. Box 3990, Columbus, Ohio, 43218-3990 or emailed to sounddscc.dla.mil. Since contact information can change, you may want to verify the currency of this address information using the ASSIST Online da
8、tabase at http:/assist.daps.dla.mil. FSC 5965 -,-,-MIL-PRF-25670B w/AMENDMENT 2 2 2.2 Government documents. 2.2.1 Specifications, standards, and handbooks. The following specifications, standards, and handbooks form a part of this document to the extent specified herein. Unless otherwise specified,
9、the issues of these documents are those cited in the solicitation or contract. FEDERAL STANDARDS FED-STD-H28 - Screw-thread Standards for Federal Services. COMMERCIAL ITEM DESCRIPTIONS A-A-52024 - Compass, Magnetic: Surveyors and Transit, Pocket; With Optional Ball and Socket or Ball and Socket Head
10、, and Jacobs Staff. DEPARTMENT OF DEFENSE SPECIFICATIONS MIL-F-14072 - Finishes for Ground Based Electronic Equipment MIL-PRF-87819 - Headset-Microphone, (Hearing Protection Type, High and Moderate Ambient Noise Levels), General Specification for DEPARTMENT OF DEFENSE STANDARDS MIL-STD-202 - Electro
11、nic and Electrical Component Parts, Test Methods for MIL-STD-810 - Environmental Test Methods and Engineering Guidelines MIL-STD-1285 - Marking of Electrical and Electronic Parts (Copies of these documents are available online at http:/assist.daps.dla.mil/quicksearch/ or http:/assist.daps.dla.mil fr
12、om the Standardization Document Order Desk, 700 Robbins Avenue, Building 4D, Philadelphia, PA 19111-5094.) 2.3 Non-government publications. The following documents form a part of this document to the extent specified herein. Unless otherwise specified, these issues of the documents are those cited i
13、n the solicitation or contract. AMERICAN NATIONAL STANDARDS INSTITUTE (ANSI) ANSI S1.12 - Laboratory Standard Microphones, Specifications for ANSI S3.2 - Method for Measuring Intelligibility of Speech Over Communication Systems ANSI S3.7 - Method for the Coupler Calibration of Earphones (Copies of t
14、hese documents are available online from http:/www.ansi.org or from the American National Standard Institute, 25 West 43 Street, 4thFloor, New York, NY 10036.) ASTM INTERNATIONAL ASTM B 545 Tin, Electrodeposited Coatings of (Copies of this document are available online at http:/www.astm.org or from
15、the ASTM International, P.O. Box C700, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959.) Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-PRF-25670B w/AMENDMENT 2 3 2.4 Order of precedence. In the event of a conflict between the text of th
16、is document and the references cited herein (except for related specification sheets), the text of this document takes precedence. Nothing in this document, however, supersedes applicable laws and regulations unless a specific exemption has been obtained. 3. REQUIREMENTS 3.1 Specification sheets. Th
17、e individual item requirements shall be as specified herein and in accordance with the applicable specification sheets. In the event of any conflict between the requirements of this specification and the specification sheets, the latter shall govern. 3.2 Qualification. Earphones furnished under this
18、 specification shall be products that are authorized by the qualifying activity for listing on the applicable qualified products list before contract award (see 4.3 and 6.3). 3.3 Materials. All materials shall enable the parts to meet the requirements of this specification. Materials, which have mea
19、surable changes in property due to aging, shall not be used, such as natural rubber-based products or ferrite-based magnets. All metal surfaces shall be corrosion-resistant. Cementing compounds (adhesives), which are water-soluble, shall not be used. 3.3.1 Insulating and impregnating compounds. Such
20、 compounds applied shall not in any way degrade the performance of conductor insulations, to which they are applied. Neither shall they corrode or otherwise cause the deterioration of adjacent materials (metals, plastics, etc.). 3.3.2 Diaphragm material. The diaphragm material shall be mylar, or a m
21、aterial having equivalent or superior flexibility, stability and durability under specified conditions, as approved by the qualifying activity. 3.3.3 Pure tin. The use of pure tin, as an underplate or final finish, is prohibited both internally and externally. Tin content of earphone components and
22、solder shall not exceed 97 percent, by mass. Tin shall be alloyed with a minimum of 3 percent lead, by mass (see 6.7). 3.4 Interface. 3.4.1 Interface requirements. Earphone elements shall be designed in accordance with the applicable specification sheet and the general requirements specified herein.
23、 3.4.2 Transformers. If a transformer is used, it shall be located inside the earphone element case, to ensure low-profile and smooth installation in headset earcups. 3.4.3 Threaded parts. All threaded parts shall be in accordance with FED-STD-H28, to ensure interchangeability of spare parts. 3.4.4
24、Finish. Final finish shall withstand the conditions cited in MIL-F-14072, Type I (Exposed). 3.4.5 Coil clearance. The voice coil shall not rub against adjacent parts after assembly. Irregularities of the voice coil surface, resulting from fabrication processes, are considered to be a part of the voi
25、ce coil. 3.4.6 Diaphragm. The earphone elements shall be constructed to have equalization of pressure on both sides of the diaphragm when subjected to changes in ambient pressure as low as 3.4 inches of mercury (1.67 pounds per square inch). Provided by IHSNot for ResaleNo reproduction or networking
26、 permitted without license from IHS-,-,-MIL-PRF-25670B w/AMENDMENT 2 4 3.4.7 Weight. Weight shall be as specified (see 3.1). 3.4.8 Color. Color shall be as specified (see 3.1). 3.5 Performance. 3.5.1 Frequency response (see 4.5.2). The frequency response at ground level shall be within the limits sp
27、ecified in the frequency response range (see 3.1). The frequency response at simulated altitude, when specified (see 3.1), shall be performed for qualification and in group C only and shall be within the limits specified in the frequency response range. 3.5.1.1 Smoothness of frequency response curve
28、. The response in the 1,000 to 5,000 Hz range shall not vary by more than 3 dB, within any 500 Hz increment. 3.5.2 Sensitivity (see 4.5.3). The sensitivity shall be as specified (see 3.1). 3.5.3 Impedance (see 4.5.4). The impedance at 1,000 Hz, measured at 20 C, and between 100 Hz and 3,000 Hz, shal
29、l be within the specified limits (see 3.1). 3.5.4 Harmonic distortion (see 4.5.5). The harmonic distortion shall not exceed the specified percent (see 3.1). 3.5.5 Dielectric withstanding voltage (see 4.5.6). There shall be no arcing or breakdown between the points of contact. 3.5.6 Stray magnetic fi
30、eld (see 4.5.7). The stray magnetic field of the earphone element shall cause no more than the specified deflection (see 3.1) of a magnetic compass at the distance as specified (see 3.1). 3.5.7 Effect of stray magnetic field on the earphone element (see 4.5.8). The earphone element shall suppress no
31、ise due to a stray magnetic field, by not generating a discernible signal. 3.5.8 Speech intelligibility (see 4.5.9). The intelligibility scores shall meet or exceed 95 percent, for an ambient sound pressure noise level not exceeding 75 dB overall sound pressure level. The elements shall be installed
32、 in standard headsets meeting MIL-PRF-87819, and tested in a representative operating Intercommunication Set AN/AIC-250, or equivalent. 3.5.9 Endurance (see 4.5.10). The frequency response and sensitivity shall not vary more than 3 dB from the initial readings recorded in accordance with 3.5.1 and 3
33、.5.2, respectively. Following the test, the harmonic distortion shall be as specified (see 3.5.4). 3.5.10 Moisture resistance (see 4.5.11). The product shall resist degradation in performance due to moisture penetration, and the frequency response, sensitivity, harmonic distortion, and dielectric wi
34、thstanding voltage shall be as specified in 3.5.1, 3.5.2, 3.5.4, and 3.5.5, respectively. There shall be no loosening or deformation of parts or other damage due to exposure to moisture. 3.5.11 Barometric pressure (reduced) (see 4.5.12). The product shall resist degradation in performance due to bar
35、ometric pressure, and the frequency response and sensitivity shall not vary more than 3 dB from the initial readings recorded in accordance with 3.5.1 and 3.5.2, respectively. 3.5.12 Thermal shock (see 4.5.13). The product shall resist degradation in performance, when exposed to alternating temperat
36、ure extremes. The frequency response and sensitivity shall not vary more than 3 dB from the initial readings recorded in accordance with 3.5.1 and 3.5.2, respectively. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-PRF-25670B w/AMENDMENT 2 5 3.5
37、.13 Vibration, high frequency (see 4.5.14). The product shall resist degradation in performance due to high frequency vibration, exhibiting no structural failure or other defects as a result, and the frequency response and sensitivity shall not vary more than 3 dB from the initial readings recorded
38、in accordance with 3.5.1 and 3.5.2, respectively. 3.5.14 Shock (specified pulse) (see 4.5.15). The product shall resist degradation in performance due to shock, exhibiting no evidence of breaking, cracks, deformation or loosening of parts, which would cause the product to fail. Minor dents and scrat
39、ches, which do not impair acoustic performance, shall be ignored. Following the test, the frequency response and sensitivity shall not vary more than 3 dB from the initial readings recorded in accordance with 3.5.1 and 3.5.2, respectively. 3.5.15 Salt atmosphere (corrosion) (see 4.5.16). The product
40、 shall resist degradation in performance due to salt-fog and shall meet the specified frequency response envelope (see 3.5.1) as specified (see 3.1), sensitivity (see 3.5.2) and dielectric withstanding voltage (see 3.5.5) requirements. 3.5.16 Fungus resistant (see 4.5.17). The product shall be const
41、ructed of fungus-inert materials, and shall show no evidence of fungus or other corrosion, which may cause a mechanical failure. The frequency response and sensitivity shall not degrade due to fungus and shall be in accordance with 3.5.1 and 3.5.2, respectively. 3.6 Marking. Earphone elements shall
42、be marked in accordance with MIL-STD-1285, with the type designation, date code, and the manufacturers Contractor And Government Entity (CAGE) code, as specified (see 3.1). 3.7 Workmanship. Earphone elements shall be processed in such a manner, as to be uniform in quality. They shall be free from lo
43、ose parts, excess solder, sharp edges, burrs, flaking, scratches, peeling, metal chips, and other foreign material. Soldering, impregnation of coils, plating, staking, riveting, and machine screw assemblage shall be neat and thorough. The coil shall be properly centered; void of foreign objects in t
44、he air gap and shall not drag on the frame or magnet. There shall be no foreign material present in the air gap, when viewed through a microscope having a minimum magnification of 15. 3.8 Recycled, recovered, or environmentally preferable materials. Recycled, recovered, or environmentally preferable
45、 materials should be used to the maximum extent possible provided that the material meets or exceeds the operational and maintenance requirements, and promotes economically advantageous life cycle costs. 4. VERIFICATION 4.1 Classification of inspections. The inspection requirements specified herein
46、are classified as follows: a. Qualification inspection (see 4.3). b. Conformance inspection (see 4.4). Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-PRF-25670B w/AMENDMENT 2 6 4.2 lnspection conditions. Unless otherwise specified, all inspectio
47、ns shall be performed in accordance with the test conditions specified below. a. Temperature - Room ambient, +15 C to +35 C. b. Pressure - Normal atmospheric. c. Humidity - Room ambient up to 90 percent relative humidity. All acoustical measurements shall be made above a reference level of 20 micro-
48、Pascal (Pa). All acoustical testing shall be made in a free-field environment. A “free-field environment” is one, which simulates free-field conditions to the extent that the inverse-pressure versus distance law or inverse-square law (sound level drops 6 dB for every doubling of the distance from th
49、e source) should hold within 1 dB at all frequencies, for which measurements are made. If the 2 (two) distances in question are d1and d2, then the decibel difference D is: D = 20 log (d1/d2). Ambient noise shall not change the measurements more than 1 dB. 4.3 Qualification inspection. Qualification inspection shall be performed at a laboratory acceptable to the qualifying activity (see 6.3) on sample units produced with
