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Old 13th December 2013, 09:50 AM   #2071
xrk971 is offline xrk971  United States
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Quote:
Originally Posted by wesayso View Post
Asus Xonar Essence ST soundcard is not a bad start and with an add on card it can be multi channel...
Thanks Wesayso.
Yes, I have looked at this and it looks nice. It may end up more than a miniDSP but you get more channels.
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Old 13th December 2013, 02:55 PM   #2072
Carlp is online now Carlp  United States
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You're a FC machine, X!
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Old 13th December 2013, 02:57 PM   #2073
xrk971 is offline xrk971  United States
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Thanks Carl
Figuring out how to internally brace this is tricky.
Having fun and almost running out of FC again.
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Old 14th December 2013, 02:25 PM   #2074
xrk971 is offline xrk971  United States
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Default Teardrop Build Completed

The Tear Drop foam core speaker is now completed. The build was a lot of fun and demonstrates the ability of FC to form smooth complex curves with an inflection (concave on both sides at different points). I was able to fit my hand and glue gun inside the cavity once the cap was cut off in order to glue the 3 internal braces which form a 6-pointed star spider. Even without the brace, the structure was very rigid. I filled it with denser stuffing in the tail and progressively going to very light stuffing in the main cavity and the front 1/3 without any stuffing. Added some 24 ga Cat5 wiring with crimp terminals, and away we go...

How does it sound? Very nice, similar to the Nautaloss and very transparent, in that the speaker disappears as there are no hard edges for diffraction.

A very cool speaker for the FC builder with some more advanced curve-forming skills. About 4 hrs total build time.

This speaker can benefit from a driver with a round bezel.

Measurements next...

Click the image to open in full size.
Attached Images
File Type: png Teardrop-3-zeppelin.png (402.7 KB, 397 views)
File Type: png Teardrop-2-brace.png (432.7 KB, 425 views)
File Type: png Teardrop-4-cap.png (440.0 KB, 379 views)
File Type: png Teardrop-5-final.png (416.1 KB, 936 views)

Last edited by xrk971; 14th December 2013 at 02:28 PM.
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Old 14th December 2013, 02:40 PM   #2075
xrk971 is offline xrk971  United States
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Default Measurements of Tear Drop and Nautaloss

After realizing that I was measuring room effects which caused a drop-off at 300 Hz, I was more careful with arranging the setup this time. I skewed the speaker axis 45 deg to room walls, added a sheet of 2 in thick open cell foam on the floor beneath speaker and mic. Put a pillow underneath the mic tripod, and draped a loose blanket over the tripod legs. Note that my measurement only goes up to about 5-6 kHz as the laptop soundcard has a low pass filter.

The measurements were made at a height of approximately 35 to 39 in high off the floor and 4 in away from speaker cone.

The "room treatments" were amazing in that the 300 Hz drop off immediately disappeared and the bass extension goes to the approx 150 Hz that was predicted by the model for the Nautaloss. Here are the measurements of the Nautaloss with the room treatments (green) compared with the old (red) and compared with the Tear Drop (blue).

Click the image to open in full size.

Both speakers performed quite well with the Nautaloss getting the edge in flatness of frequency response in the higher registers.

Here is the Nautaloss measurement with THD and Phase also shown:

Click the image to open in full size.

Here is the Tear Drop measurement with THD and Phase:

Click the image to open in full size.

The THD figure of -50 dB from 200 Hz on up is quite amazing. The Nautaloss also gets the nod for the impulse response as the Tear Drop, although very good, has a slightly higher secondary negative peak.

I think that either of these would be excellent choices for near-field critical listening as monitors above 200 Hz.
Attached Images
File Type: png Teardrop-Cochlear-Compare-Meas-4in-39inhigh.png (52.9 KB, 459 views)
File Type: png Cochlear-Meas-4in-39inhigh.png (47.8 KB, 588 views)
File Type: png Teardrop-Meas-4in-39inhigh.png (57.1 KB, 465 views)

Last edited by xrk971; 14th December 2013 at 02:44 PM.
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Old 14th December 2013, 03:21 PM   #2076
tb46 is offline tb46  United States
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Hi xrk971,

This is all very neat :-). Have you tried to use your Nautalos as a BLH w/ the driver (or drivers) mounted in the center? Also, you can add your tractrix horn pointed sideways.

Regards,
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Old 14th December 2013, 03:26 PM   #2077
IG81 is offline IG81  Canada
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Pretty cool! These measurements are more like it and nicely flat overall.

IG
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Old 14th December 2013, 03:27 PM   #2078
xrk971 is offline xrk971  United States
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Well that becomes a Cornu BLH. I have not specifically tried the 36 in long Nautaloss spiral as a BLH. It would not produce very deep bass at 150 Hz.
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Old 14th December 2013, 03:31 PM   #2079
tb46 is offline tb46  United States
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Hi X,

You're probably correct looking at path length and mouth size.

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Old 15th December 2013, 11:29 AM   #2080
xrk971 is offline xrk971  United States
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The spiral Nautaloss is good enough for me to commence with the stereo pair for the first unit. In progress...
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