{"product_id":"1962-chapman-model-305-audio-amplifier-for-restoration","title":"1962 Chapman Model 305 Audio Amplifier For Restoration","description":"\u003ch1\u003e1962 Chapman Model 305 Audio Amplifier For Restoration\u003c\/h1\u003e\n\u003cp\u003e\u003cspan lang=\"EN-US\"\u003eOn offer today we have a vintage 1962 Chapman Model 305 Audio Amplifier For Restoration. Cosmetics are generally good, with the black grille cover slightly blemished with scuffs and corrosion, and a few scratches on the sides of the amp.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan lang=\"EN-US\"\u003eManufactured by the well regarded British manufacturer Chapman Reproducers Ltd. \/ Derritron Ultrasonics, this amplifier is not a plug and play but a rare survivor of a compact footprint alternative to the Mullard 5-10\u003c\/span\u003e.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eApproximate Size (WHD)\u003c\/strong\u003e:-  30 x 14 x 7.2cm\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"color: #ff2a00;\"\u003e\u003cstrong\u003eWe are selling this amplifier as a Restoration project only. This is not for immediate connection to a mains power supply. The amplifier will be supplied with the input socket covered with a \"Failed' PAT test label stating \"For Restoration Only.'\u003c\/strong\u003e\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003eIt is offered in 'restoration condition' as it has been in storage for many years without use and, therefore, has not been powered. Accordingly, the passive components will probably have aged with the resistors having 'gone high,' and the electrolytic capacitors probably showing leakage. \u003cspan lang=\"EN-US\"\u003eOn removing the baseplate, we note that numerous capacitors have been replaced but the signal input and mains input have not yet been installed.  \u003c\/span\u003e\u003c\/p\u003e\n\u003cp class=\"MsoNormal\"\u003e\u003cspan lang=\"EN-US\"\u003e The valve line up is as follows:-\u003c\/span\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli class=\"MsoNormal\"\u003e\u003cspan lang=\"EN-US\"\u003eRectifier:- a yellow print Mullard EZ81, \u003c\/span\u003e\u003c\/li\u003e\n\u003cli class=\"MsoNormal\"\u003e\u003cspan lang=\"EN-US\"\u003eInput stage:- two Mullard Old Shield ECC83\u003c\/span\u003e\u003c\/li\u003e\n\u003cli class=\"MsoNormal\"\u003e\u003cspan lang=\"EN-US\"\u003eOutput stages:- four Mullard EL84.    \u003c\/span\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cspan lang=\"EN-US\"\u003eAll seven valves have been tested and give good emission. \u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan lang=\"EN-US\"\u003eThis example dates from approximately 1962 when Chapman Reproducers Ltd. changed their trading name to Derritron Ultrasonics after being acquired by the Derritron Group in 1960. It carries a makers plaque with this name under the top grille on the RHS of the top deck.   \u003c\/span\u003e\u003c\/p\u003e\n\u003cp class=\"MsoNormal\"\u003e\u003cspan lang=\"EN-US\"\u003eThe circuit topology presents as dual mono \u003c\/span\u003e\u003cspan\u003eultra-linear output stage, comprising two EL84 valves in push-pull, feeding a grain concentrated Partridge transformer type 8913.  This is the type of output stage normally used in high quality monaural amplifiers, providing no compromise in performance and reliability, and ensuring long life and long term stability.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp class=\"MsoNormal\"\u003e\u003cspan\u003eFrom research, the specification was found to be:-\u003c\/span\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli class=\"MsoNormal\"\u003e\u003cspan\u003eInput sensitivity 350m\/V RMS for 8 watts output.\u003c\/span\u003e\u003c\/li\u003e\n\u003cli class=\"MsoNormal\"\u003e\u003cspan\u003eFrequency response within 0.2dB 30-20,000Uz range\u003c\/span\u003e\u003c\/li\u003e\n\u003cli class=\"MsoNormal\"\u003e\u003cspan\u003eValves 2 x ECC83 ; 4 x EL84 and EZ81.\u003c\/span\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003ePlease click on the following link for more \u003ca href=\"https:\/\/mullardantiques.co.uk\/collections\/vintage-hifi-and-accessories\" target=\"_blank\"\u003evintage HiFi\u003c\/a\u003e \u003c\/p\u003e","brand":"Chapman Reproducers \/ Derritron Ultrasonics","offers":[{"title":"Default Title","offer_id":57170187157879,"sku":null,"price":349.99,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0303\/5122\/8972\/files\/1962_Chapman_Model_305_Audio_Amplifier_For_Restoration.jpg?v=1781538480","url":"https:\/\/mullardantiques.co.uk\/products\/1962-chapman-model-305-audio-amplifier-for-restoration","provider":"Mullard Antiques and Collectibles","version":"1.0","type":"link"}