{"product_id":"bruel-kjaer-4220-pistonphone-microphone-accessories-excellent-w-hard-case","title":"Brüel \u0026 Kjær 4220 Pistonphone - Microphone Accessories - Excellent w\/ Hard Case","description":"\u003ch3\u003eWhy this one\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003eExcellent condition - light signs of use, no obvious issues\u003c\/li\u003e\n  \u003cli\u003eFully tested - flawless results across all functional checks\u003c\/li\u003e\n  \u003cli\u003eDelivers 124 dB at 250 Hz with ±0.2 dB calibration accuracy.\u003c\/li\u003e\n  \u003cli\u003eComes complete with its original hard case - protected and ready to deploy.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eCondition: Excellent\u003c\/h3\u003e\n\n\u003cp\u003eThis microphone accessory is in excellent condition. It has passed our full 5-point functional test with perfect results. Please review all photos carefully, as they provide an accurate representation of the cosmetic condition of the product.\u003c\/p\u003e\n\n\u003ch3\u003eWhat's included\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003eBrüel \u0026amp; Kjær 4220 Pistonphone\u003c\/li\u003e\n  \u003cli\u003eHard Case\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eAbout this model\u003c\/h3\u003e\n\u003cp\u003eThe Brüel \u0026amp; Kjær 4220 is a precision pistonphone - a compact, battery-operated acoustic calibrator designed for verifying the accuracy of sound level meters and measurement microphones. It generates a pure 250 Hz tone at exactly 124 dB SPL at the microphone diaphragm, with a calibration accuracy of ±0.2 dB. Its two symmetrically mounted pistons and floating retaining spring design eliminates shaft eccentricity and bearing backlash, ensuring highly repeatable results. The unit accepts 1\", 1\/2\", 1\/4\", and 1\/8\" microphones via adaptors and operates across a temperature range of - 10 to +55°C, making it suitable for both laboratory and field use.\u003c\/p\u003e\n\n\u003cp\u003eA great opportunity to own a Brüel \u0026amp; Kjær 4220 Pistonphone at this price point.\u003c\/p\u003e","brand":"Brüel","offers":[{"title":"Default Title","offer_id":55147467833681,"sku":null,"price":315.0,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0775\/6913\/0833\/files\/dbcf0249-ddb6-4180-b446-66c0bc3bc3eb.jpg?v=1790865672","url":"https:\/\/www.audiotrader.co.uk\/products\/bruel-kjaer-4220-pistonphone-microphone-accessories-excellent-w-hard-case","provider":"Audio Trader","version":"1.0","type":"link"}