Pair Vintage Altec Lansing 291-16A Field Coil Drivers Start Price USD 1,650.00 Current Price USD 1,650.00 Time Left - Bid Count 0 Buy It Now Price - Reserve Price - Start Time Monday, October 06, 2008 End Time Monday, October 13, 2008 Location Stanton, California See more about 'Pair Vintage Altec Lansing 291-16A Field Coil Drivers' Description This is a second time, I am proud to introduce you on the auction a beautiful pair ALTEC LANSING 291-16A FIELD COILs (Please refer to the pictures) a renovation of the Lansing 287 FIELD COIL in a very SIMILAR appearance, TECHNICAL and SPECIFICATION.   You need a 60VDC power supply to operate the field coil.   Both Field Coil drivers are perfectly working.   Each driver weighs 25 lbs before packing.   The auction includes (2) 291-16A drivers and (2) Mint Original 291-16A Diaphragms in flawless condition. Both are measured 11.7 Ohms. They are 16-Ohm impedance, however, some audiophiles consider as 24-Ohm impedance.   Our research along with many audiophile friends is to maximize the weight of the copper Field Coil and minimize the distance between field coil and the coil gap to  delivery a stable and maximum  magnetic field to the voice coil gap.   ************************************************************_     ___Below is a description that posted on EBAY more than 3 months ago. Note: The 288 and 291 series have exactly the same structure except the diaphragm.___ ___Note: The edge of 291 series diaphragm is dopped with symbiotic to eliminate the unexpected noise that created from surrounding of the aluminium dome__   This is a remarkable modification of the famous AlNiCo Altec Lansing 288 driver to Field Coil Magnet which is similar to the Lansing 287. Back in the old day by the transition of converting all field coil to AlNiCo permanent magnet Altec Lansing Company held the same structure of 287 and converted it to AlNiCo 288 red-white-blue model which represent all the 288 bubble cover cap series. The structure of Altec 288 and 287 is very similar except the magnet and a bit different at the edge of the diaphragm;   Does it really matter between the two different types of magnet? Does it make the vibration of the diaphragm response differently? Which one is more stable, uniform and stronger magnetic field than the other? Is it valuable to convert AlNiCo to field coil? Along with my many audiophile-friends and for more than 6 years of experience listening and study to of vintage speakers I will try to answer these tough questions.   The field coil feeds its magnetic field by a provided current. As long as the current is constant the field coil must be constant. Thus the field coil can produce very stable and uniform magnetic field. Nowadays, we have a big advantage compare to the old TUBE days that many DC power supplies are available, stable, high quality and affordable that can be used to supply power for the field coil. On the other hand, while the speaker playing (especially at high frequencies) the AlNiCo or any permanent magnet certainly can not be able to supply a stable or uniform magnetic field spontaneously, continuously but instead the atoms or molecules randomly change their magnetic poles then trying to self-align to gain the total strength. This is a reason why the vibration of a diaphragm is out of control and produces a tremendous amount of unexpected high pitch due to unstable Magnetic Field. You may confuse the high pitch with the desired high frequency reproduction. This unexpected high pitch may kill your ear, like someone scratches his fingers on the black board.   The strength of magnetic field is not difficult to conquer by FIED COIL. I will not mention this and leave it for you. The most and very important role in sound reproduction is the UNIFORM and STABLE of Magnetic Field as mentioned earlier.    The models  AlNiCo Altec 288 (288, 288B, 288C, 288G, 288H, 288L, 288-8K, 288-16K) and also IPC, 291-16A, 299 and early 290 are sensitive with clear, present, detail and “loud” (plus noise too!) similar to the famous JBL 375 AlNiCo that is a renovation of the famous WE 594A field coil. However, the 288 series and JBL 375 has a serious sound defect at the peak of the sound wave when diaphragm moving to the peak (the farthest distance from at rest). This high pitch noisy sound makes many listeners are confused between the “LOUD” high frequency noise and the desired music of “WARM” high frequency reproduction. In the other words, AlNiCo drivers produce distortion that you can hear when the diaphragm moves to the peak. The sound is “cracked” like “a tip hair has split end.” The cracked sound may reduce 30% to 50% when couple with horn especially to the ALTEC 311-90 horn because of the air pressure changing smoother than without horn. Incredibly, The Field Coil Magnet amazingly solves this problem even without using any horn.      The 288 field coil performs in a very different manner compare to AlNiCo. It sounds extremely smoother, warmer, very musical playback. It does not torture your ear when the music loud as the 288 AlNiCo does (especially the Altec 299).         You may view the ALTEC 288C link below:   288C:  http://www.voiceofthetheatre.com/images/288C%20copy.jpg   288C: http://www.voiceofthetheatre.com/images/288C.2.jpg And 291-16A: http://www.voiceofthetheatre.com/images/291.16A.1.jpg 291-16A: http://www.voiceofthetheatre.com/images/291.16A.2.jpg   You may expect shipping shall be costly.   Thank you for your patient to visit my auction and wordy description.   Very important note: PLEASE DO NOT BID IF YOU ARE NOT SURE TO PAY OR WORRIED about high SHIPPING COST.             Place a Bid!