Posted by Wayne Parham [ 22.214.171.124 ] on October 15, 2005 at 14:20:16:
In Reply to: Re: Hornsub shootout RESULTS posted by Wayne Parham on October 15, 2005 at 12:02:43:
The Tuba 24 was the first to be tested. It weighs in at about 65 lbs and measures 24" x 24" x 24". It uses a single Eminence HL10A, although this one has a prototype HL10C driver. The difference is the C model is 4 ohms and has a smaller 0.75" cooling vent. Other than that, performance appears to be identical.
Dimensions: 24" x 24" x 24"
Power handling: 300wrms
Impedance: 6Ω or 12Ω (depending on driver)
Frequency range: 40Hz - 200Hz
Max Output: 128dB/M
Distortion at 100 watts: 5%
First, we measured impedance and found Zmin to be 6.0Ω. So 24.5v is required for 100 watts, 34.6v for 200 watts, 49v for 400 watts and 60v for 600 watts.
Next, we measured output at 28.28v. This is a little more than 100 watts. Since we measured 10 meters away, the values correspond to 2.83v/1M.
From this, we perform an inverse FFT to obtain impulse and step response:
Measurement at 100 watts:
The blue line is SPL, and the violet line shows distortion. Average distortion is 25dB under the fundamental, which is about 5%. Since measurement was taken at 10 meters, add 20dB to find SPL at 1 meter. With 100 watts input, the 10 meter measurement works out the same as 1 watt input measured at a distance of 1 meter.
Measurement at 200 watts:
Output at 200 watts measured at 10 meters is about 105dB average between 70Hz and 170Hz, which is 125db at 1 meter.
Measurement at 400 watts:
Output at 400 watts measured at 10 meters is about 108dB average between 70Hz and 170Hz, which is 128db at 1 meter.
Measurement at 600 watts:
Increasing power from 400 watts to 600 watts results in little increased acoustic output.
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