This page is authored by W. Marshall Leach, Jr.<\/p>\n\n\n\n
LSR&D:<\/strong> In the latter 1970s, three engineers who\n worked at the Georgia Tech Research Institute approached me with the \nidea of forming a company to manufacture and market audio power \namplifiers. This was the beginning of LSR&D, Inc. The letters L, S, \nR, and D were the first letter of the last name of the original four \npartners. One of the partners soon dropped out, but he was replaced soon\n after that. Our first product was a stereo amplifier which we called \n«The Leach Amp.» It was rated at 160 watts per channel into 8 ohms. It \nwas based on a circuit which I had published in Audio Magazine in 1976 \nand1977 in two papers titled «Build a Low TIM Amplifier.» The earliest \nLSR&D amplifiers can be identified by a dark colored E-I core \ntransformer immediately behind the front panel to the right of the \nswitch. We soon replaced this transformer with two round toroid \ntransformers. Although the toroid transformers were lighter, I always \nthought that the E-I core transformers made a «stiffer» power supply. A \nmono amplifier was introduced later. We called it «The Leach Superamp.» \nIt was based on a circuit I published in Audio Magazine in 1980 titled \n«Build a Double Barrelled Amplifier.» The Superamp was rated at 300 \nwatts into 8 ohms. Our company went out of business in the mid 1980s. \nThe three things that doomed us were financing, marketing, and \nsquabbling among partners. The two links below contain circuit diagrams \nand servicing hints for the two amplifiers. Unfortunately, I do not have\n a parts layout for the circuit board. I don’t have any of the LSR&D\n amplifiers, but I work with someone who has managed to collect several \nof them.<\/p>\n\n\n\n Electronics One:<\/strong> In the early\/mid 1970s, a former \nstudent of mine who was working part time at the company Electronics \nOne, Inc. contacted me about manufacturing an audio amplifier I had been\n working on. Electronics One was a very small company consisting on one \nengineer, one technician, and part-time help when needed. The company \noffered electronics consulting services and it manufactured small-scale \nelectronic components and systems under contract with customers. I \nsigned an agreement to allow Electronics One manufacture and sell audio \namplifiers based on circuits I had published in Audio Magazine. These \nwere stereo amplifiers rated at 100 watts per channel and were called \n«Leach LNF-1 Amplifier» and «Leach LNF-1A Amplifier.» The LNF-1 models \nwere housed in a shoe-box style chassis. The LNF-1A models were in a \nrack-mount chassis. I don’t think that the company was ever financially \nsound because of the uncertainty of the contract electronics business. \nThe owner was looking for a product, and he hoped the amplifiers would \nfill that need. But the company failed and the owner sold it sometime in\n the latter 1970s. It had closed, vacated its building, and the owner \nhad left town before I knew anything about the failure. The drawings \nlinked below are all I have on these amplifiers. There are some \nmodifications that I recommend to improve reliability. I have the \nprototype Electronics One LNF-1 and LNF-1A amplifiers in my lab and both\n are still working after all of these years.<\/p>\n\n\n\n I have seen two LNF-1A amplifiers sold on Ebay which had an auxiliary\n circuit boards mounted inside the chassis to convert the stereo \namplifier into a strapped mono amplifier. I never knew that any \namplifiers were sold with this modification. I recommend removal of the \nauxiliary circuit boards and operating the amplifiers as stereo \namplifiers.<\/p>\n\n\n\n