radiogram Posted October 25, 2010 Share Posted October 25, 2010 1. Searching the forum for K33 sensitivity, I find a wide range from 92.5dB to 98.5dB being mentioned. What is the actual sensitivity spec of the K33 Woofer? 2. As per Klipsch Cornwall II brochure, the speaker's overall sensitivty is sepcified at 101dB @ 1w/m. How did the sensitivity increase to 101dB when the K33's sensitivity is only in the 90's? Does cabinet the loading increase it? Quote Link to comment Share on other sites More sharing options...
djk Posted October 25, 2010 Share Posted October 25, 2010 Old Cornwalls were rated at 98.5dB at 4', new Cornwalls are rated at 1M, add 1.7dB for the difference in distance. Old K33E specs: Name: 15162 Type: Standard one-way driver Company: Eminence Speaker LLC Comment: K33E No. of Drivers = 1 Fs = 34.46 Hz Qms = 7.39 Vas = 301.7 liters Cms = 0.268 mm/N Mms = 79.47 g Rms = 2.328 kg/s Xmax = 8.2 mm Xmech = 12.3 mm P-Dia = 336.6 mm Sd = 889.6 sq.cm P-Vd = 0.729 liters Qes = 0.41 Re = 3.39 ohms Le = 0.96 mH Z = 4 ohms BL = 11.93 Tm Pe = 150 watts Qts = 0.388 no = 2.903 % 1-W SPL = 96.78 dB 2.83-V SPL = 100.5 dB Quote Link to comment Share on other sites More sharing options...
radiogram Posted October 25, 2010 Author Share Posted October 25, 2010 Djk - Thanks. Now this is interesting - 1W SPL = 96.78 dB; 2.83V SPL = 100.5. The only value of R being nominal impedence for which 2.83V would yield an increase of 3.72dB compared to 1Watt is R=3.4 Ohms, which is actually same as the Re. However, ALK has actually measured the K33's nominal impedence to be around 6 Ohms. If we use 6 Ohms, then @ 2.83 V the SPL will be higher by 1.25 dB compared with 1 Watt. Now, I am confused. Quote Link to comment Share on other sites More sharing options...
djk Posted October 26, 2010 Share Posted October 26, 2010 The 100.5 dB is a computed value from T/S taking into consideration the motional impedance (BassBoxPro v6.0). The actual impedance at 224hz is 3.42 ohms, at box resonance it is about 4.38 ohms ( a phase angle of 0° on both), it rises to around 6 ohms with a phase angle of about 56° around 875hz. Impedance and efficiency are a moving target, one number doesn't really describe what's going on. BB says the driver hits 101.5dB at 150hz with 2.83V in a Cornwall sized and tuned box. The 15162 spec is a late 70s vintage K33E (AFAIK). Remember too, a type B network has about 0.5 ohms DCR on the inductor, and that will reduce the level a bit from these numbers, as much as 0.8dB IIRC. Modern practice is to add 3dB~4dB for 'room gain' to the 'hard numbers', Quote Link to comment Share on other sites More sharing options...
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