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Vend Altec 515 A
Auteur Message
Senior Member

Messages : 350
Groupe : MELAUDIA.membre
Inscription : 11/04/2010
Statut : Hors ligne
Message : #11
RE: Vend Altec 515 A

la traduction exacte du vendeur sur Ebay:

Last chance to buy these. If I get no bids this time, I'll box them up and put them back on the shelf for a while.

I was the Senior Engineer for acoustic products with Altec Lansing in the 1980's at the Oklahoma City facility and these speakers are from my personal collection.

The original model 515 woofer was well suited for the large vented straight bass horn enclosures like the 210 and 211 models it was used with when installed in movie theatres across the USA in the 1940's and 50's. With its high gap flux density, flat wire voice coil and light moving assembly, its conversion efficiency was very high to match the sensitivity of the 288 HF compression driver on the multicellular horns of the day. Available audio amplifier power was typically only 10-30 watts.

In my quest to build the ultimate bass horn driver for large (eight foot path length) folded horns using reactance annulling with a small back air chamber, I reconed these woofers in 1990 using the standard 8 ohm voice coil from the 416/604, and the low mass 21184-4 cone used in later model 515B's. The slightly stiffer, but more stable tan spider was also used. To eliminate front-to-back losses from air leakage, the vented dust cap was replaced with a solid one, with venting accomplished through perforations in the voice coil support as was done with the 420/417/418. The photos show the custom designed bass horn enclosures used with these drivers in a D'Appolito array system, including a 299-8A HF driver on a 511E horn (I was the design engineer for the 299 driver). A signal delay for the high frequency section provided correct time/phase alignment at the 500 Hertz crossover frequency. This system had bandwidth down to 40 Hertz, low distortion, and with a modest amount of audio power, could produce 105 dB SPL outdoors, at 100 feet from the system. Email with any questions you may have about the woofers or the bass horn enclosures, which may also be for sale.

I am retiring from audio engineering after 43 years and no longer have the space for these old gems. If you are considering some unique vintage woofers for your home hi-fi or other project, these speakers might be just what you are looking for. They are in excellent working condition, with some of the magnet structures obviously missing some paint. One of them is the currently sought after "RWB" version. Total service time on these woofers is less than 100 hours with normal program material. The measured Thiele-Small parameters for these drivers have little variation from unit to unit and the average values are as follows: Re = 6.9 ohms, Fs = 26.4 Hz, Qts = 0.242, Qes = 0.250, Qms = 7.99, Le = 0.68 mH, Vas = 23.2 cubic feet, Mms = 57.0 grams. These drivers are essentially an eight ohm 515B.

08/11/2018 10:23:11
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