Nht 1259

[zlast]

I was measuring the T/S parameters of the NHT 1259 (origonal 4 ohm version) using the process outlined here:

http://sound.westhost.com/tsp.htm

Using a computer with tone generating software, 10.1 ohm resistor and multimeter, and the LS-PARAM.XLS I get the following results:

QMS: 3
QES: .66
QTS: .54
VAS: 150 liters

I am using a 45 liter sealed enclosure for the VAS measurement, with the same tone generator - resistor - multimeter setup as above. QMS, QES, QTS are all near manufacturer specifications, but VAS is considerably different than the 190-230 liters specified by the manufacturer. Has anyone else measured the 4 ohm 1259? Are my measurements off ? Is there some flaw in my measurements? I have repeated the measurements 3 times and get similar results. The 1259s are from the ORIGONAL group purchase through Ken Kantor....anyone else own/measured these? Are the parameters different than later 1259s ?

[infinia]

Hi
What was the measurement of both fs's?

edit> I mean free air Fs and 44 liter Fb.
I would be upset when Vas was larger than spec.

[zlast]

Free air (suspended about 4 feet off floor - no objects within 3 feet) = 20 Hz

FS is 45 liter enclosure = 40 Hz

Both measurements made with the tone generator, resistor, multimeter setup. THe concern about accurate measurements is over designing a Linkwitz transform circuit for several drivers. I started with the 1259 and want to make sure the results are correct befor designing the transform circuit. Any ideas ?

[infinia]

Hi Zlast
I would just put them in a reasonably small sized box using your meas T/S. I don't think you'll be too far off using your meas. Vas. Re-measure Fb, Q in the final enclosure and use those for the LT circuit. Design the LT for new Fs and Q watching gain doesn't go much above 8-10 dB.

BTW I calc Vas = 140 liters