Free Field
This first measurement I took last. I placed the LM-1C on a Hsu subwoofer and measured a foot away. Very smooth response:
In the bass 80 Hz is about -4 dB, but please note the extension to 20kHz! This is a perfect HT speaker! Especially for the outlay. I strongly suspect on a dedicated stand it would be even better. The curve is so close to ideal I won't bother with EQ here.
On Entertainment Center
Jaggedness below 500 Hz attributable to the usual room/speaker interactions, however the upper shape of the response is pretty much on target. One good thing though is that the sensitivity at 1 kHz is actually a little better than predicted, and the response from around 600 Hz to 1 kHz is much smoother than predicted, a good thing. Plot was taken with 1/24th octave smoothing.
I also took the liberty of running some distortion measurements at 1 watt. The measurements past 800 Hz are all below 0.35% HD. Most excellent values for the spend. I may in fact have benefitted somewhat from the bass coil having unusually high resistance. I used a pair of coils to make it, and the total coil impedance ended up being around 1.2 Ohms, yielding a much smoother mid-bass response. Never stop looking for serendipity!
Nice work!! Did you ever try ground-plane test outside. I kept trying different methods indoors but one trip outside changed all of my testing to outside.
ReplyDeleteKen
Hi Ken, thanks for your kind words. Never really felt the need to get fancier than this, and in fact for my goal might have been counter productive.
ReplyDeleteFirst, I was deliberately making a desktop/bookshelf speaker. I wanted the bass of the speakers in place, not quasi-anechoic. This gained me 2-4 dB in sensitivity and improved the smoothness of the response once in place.
Also, this being a 2-way with a relatively high crossover point, I could use gated far-field with very high resolution to get me precise data through the important region. If this had been a 3-way I would have been forced to do quasi-anechoic to get consistent results through the woofer-mid intersection.
Best,
Nigel