The sound on this Coronet Monophonic Recording is engineered to perfection and is the final product of years and research and development of monaural recording techniques. All original recordings are made with Telefunken Microphones and Ampex 350-2 and 300-3 magnetic tape recorders affording a frequency response from 20 to 20,000 cycles per second. Original master discs are cut with modified Grampion cutter on a Scully Lathe using a special amplification system.