Avcoil prototype T-7FR 8 inch field coil full range pair LAST PAIR

PLEASE NOTE THAT THIS IS THE LAST PAIR! First designed in 2007 as an optional Lowther replacement that upgrades to a field coil format. Ideal for horn loading above 80hz and can be used in a front loading cabinet with rear horn and or transmission line. Usable response of 50 to 20k depending on loading. The cone and extender cone use a proprietary pulp that is composed of various length fiber from banana, coconut, and pineapple fibers. The fibers of the pulp are spun to allow the best distribution within the cone and provide stiffness where most needed and minimize resonant peaks. This overcomes most of the problems of full range speakers which need low mass for good transients, yet maintain stiffness for extended response and low distortion. A special small center cone mechanically couples direct to the voice coil at 6k and extends response to beyond 20k to give lifelike highs. To reduce mass and allow greater high frequency distribution, a center deflector is used instead of the traditional dust cap. Made of aluminum, it also acts as a heat wick to reduce the operating temperature of both the voice and field coil. It also allows a wider distribution of sound above 10k. The development of the 8 inch speaker took several years as a new approach was desired to upgrade and improve what has been an audio staple for many years. Going back to a field coil allows the speaker to have the equivalent of a much larger permanent magnet. The advantages of large magnets in giving high flux in the gap are well known. A special copper shunt ring is also used to lower distortion and smooth impedance. A major issue that is addressed is the matching of the speaker to the amp. To minimize instability, a very smooth impedance curve has been obtained in the 50 to 20k bandwidth that varies between 6 and 22 ohms. The resonant peak is at 100 hz and the impedance slowly rises with frequency to around 24 ohms at 20k. It also minimizes the effect of the interconnect speaker cables. The use of Zobel filters should not be needed and is not recommended. This speaker is not recommended for high level listening applications such as large home theater rooms or to play rock music at concert levels. Ultra low mass is achieved giving outstanding transients and a unique musical quality that has to be heard to be appreciated. This listing is for a closely matched pair of prototype T-7 8FR. They are in good working condition with a minimum of scratches and abrasions. Developed and built by speaker designer and consultant Sam Saye. His other recent projects include the upgrade of Dr Bruce Edgar’s Titan horn system to field coil in 2005, upgrades to the Classic Audio Loudspeaker lineup to include all field coils in 2006, development assistance of the the BE 4016 beryllium diaphragm for Materion 2007-11, and most recently development of the prototype all horn field coil system for ESD Acoustics. Frequency response; 100-16k plus minus 3db. 65-20k plus minus 6db. Impedance; 16 ohm nominal. Voice coil; one inch copper on nomex former. Recommended enclosure; Open baffle of one square meter or larger, front and rear loading to 80 to 100hz horns. Transmission line can be added to extend low frequency to below 40hz. Small infinite or ported enclosure application will reduce the openness and musicality of the speaker. The item “Avcoil prototype T-7FR 8 inch field coil full range pair LAST PAIR” is in sale since Wednesday, April 10, 2019. This item is in the category “Consumer Electronics\Vintage Electronics\Vintage Audio & Video\Vintage Speakers”. The seller is “coil-guru” and is located in Lakeside, California. This item can be shipped to United States, Canada, United Kingdom, Denmark, Romania, Slovakia, Bulgaria, Czech republic, Finland, Hungary, Latvia, Lithuania, Malta, Estonia, Australia, Greece, Portugal, Cyprus, Slovenia, Japan, China, Sweden, South Korea, Indonesia, South africa, Thailand, Belgium, France, Hong Kong, Ireland, Netherlands, Poland, Spain, Italy, Germany, Austria, Bahamas, Israel, Mexico, New Zealand, Singapore, Switzerland, Norway, Saudi arabia, Ukraine, United arab emirates, Qatar, Kuwait, Bahrain, Croatia, Malaysia, Brazil, Colombia, Panama, Jamaica, Barbados, Bangladesh, Bermuda, Brunei darussalam, Bolivia, Ecuador, Egypt, French guiana, Guernsey, Gibraltar, Guadeloupe, Iceland, Jersey, Jordan, Cambodia, Cayman islands, Liechtenstein, Sri lanka, Luxembourg, Monaco, Macao, Martinique, Maldives, Nicaragua, Oman, Peru, Pakistan, Paraguay, Reunion, Viet nam, Uruguay.

• Model: T7-8FR
• Country/Region of Manufacture: United States