Pete B Posted June 19, 2018 Report Share Posted June 19, 2018 I'd like to measure an AR-5 type 8 ohm 1.5" midrange if anyone has a spare to loan. I'll post the .zma file here for general use. I'm also interested in the physical construction in case anyone has disected a dead one or would be willing to donate dead ones for me to do. I'm curious about the specs for these midranges, I have a pair of 4 ohm from AR-11 which I believe the same as the AR-3a type. I'm also interested in the physical construction, again if anyone has a dead one to donate for analysis. I measured a pair of AR-11 mids many years ago and am reposting them below, I'll remeasure them and post .zma files here. AR-11 Midrange (200010-1) Measurements 9/17/05: Midrange #1: Red label indicating that this was replaced Date code : 561 8018 Fc = 464.6 Hz Re = 3.15 ohms Qe = .92 Qm = 3.15 Qtc = .71 Midrange #2: Appears to be original Date code: 561 7812 Fc = 514.9 Hz Re = 3.18 ohms Qe = 1.04 Qm = 3.17 Qtc = .78 The impedance curve looks primarily like a simple sealed system with a fundamental resonance of 12.9 ohms at 521 Hz. Impedance is 4.0 ohms in the pass band at 3 kHz. There is a very small secondary peak of 4.27 ohms at 1098 Hz. Neither the midrange or tweeter utilize rear chambers and it is clear that the acoustical response is part of the crossover network. The midrange Fc being close to the crossover point, and the Qtc of .7 could form one section of a Linkwitz-Riley 4th order response. The acoustical response being one 2nd order section and the electrical being the other if properly designed. The large increase in impedance suggests that ferro fluid was not used in these drivers. I don't like the idea of an acoustical filter in front of the dome, however the construction of this midrange appears to be very well done. Link to comment Share on other sites More sharing options...
RoyC Posted June 20, 2018 Report Share Posted June 20, 2018 Hey Pete, I have a 1971 specimen with no screen you are welcome to. I don't remember if it is from an AR-5 or 3a. Roy Link to comment Share on other sites More sharing options...
Pete B Posted June 20, 2018 Author Report Share Posted June 20, 2018 Thanks Roy, PM sent. Link to comment Share on other sites More sharing options...
Pete B Posted June 20, 2018 Author Report Share Posted June 20, 2018 The face plate is 5.75" OD and the magnet is 4.5" OD. Link to comment Share on other sites More sharing options...
Pete B Posted June 26, 2018 Author Report Share Posted June 26, 2018 Robert, ra.ra kindly provided this drawing of the 200044 1.5" midrange that was used in the AR-58s. It includes ferro fluid and does not include a screen or front fiberglass pad but otherwise is likely the same, can anyone confirm this? The older mids did not include the glued on "Semi-horn", item 10 in that drawing. The diagram mainly provides construction details and notes but does not include actual dimensions or tolerances. Still a great diagram. 200044.tif Link to comment Share on other sites More sharing options...
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