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Foam Core Board Speaker Enclosures?
Foam Core Board Speaker Enclosures?
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Old 10th December 2013, 04:25 PM   #2031
bcmbob is offline bcmbob  United States
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You are completely out of control. That's fantastic.
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"Arrange Whatever Pieces Come Your Way."
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Old 10th December 2013, 07:47 PM   #2032
xrk971 is offline xrk971  United States
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Foam Core Board Speaker Enclosures?
Default Cochlear sealed TL - Build Completed

This things sounds great! I am surprised how much bass actually comes out of the direct radiator cone. The mids and highs are exceptionally clear - the transparency and detail are quite astonishing with the few test tracks I have listened to. I like how it sounds and I think when in stereo the sound stage will be very nice.

It is 12 in tall x 5 in wide x 9 in deep. Here it is sitting on top of the old Yamaha RX360 amp with a TPA3116D2 and a TPA3110D2 (in blue snap top lid box). Second photo is the back side so you can see the nice curves that the foam core can make.
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File Type: png Cochlear-4.png (446.4 KB, 544 views)
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Old 10th December 2013, 08:23 PM   #2033
IG81 is offline IG81  Canada
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Pretty neat! Do you have a mic for some quick measurements? I'd like to see a near-cone plot for that one. How does it compare to the small Karlsonator?

I haven't done much enclosure experimentation lately, but had the FF85WK -wave pipe trotting back in my mind lately for some reason. The foamcore prototype I made almost a year ago showed some promise. I'm pretty certain what I was going for worked to some extent, but I'd have to compare with a more standard pipe to see if it offers any advantages.

Click the image to open in full size.

IG

Last edited by IG81; 10th December 2013 at 08:31 PM.
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Old 10th December 2013, 11:59 PM   #2034
xrk971 is offline xrk971  United States
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I will try to get a measurement in next few days but first have something to try...
Remember the tractrix foam core horn I made a while ago?
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Old 11th December 2013, 01:47 AM   #2035
BP1Fanatic is offline BP1Fanatic  United States
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Quote:
Originally Posted by xrk971 View Post
This things sounds great! I am surprised how much bass actually comes out of the direct radiator cone. The mids and highs are exceptionally clear - the transparency and detail are quite astonishing with the few test tracks I have listened to. I like how it sounds and I think when in stereo the sound stage will be very nice.

It is 12 in tall x 5 in wide x 9 in deep. Here it is sitting on top of the old Yamaha RX360 amp with a TPA3116D2 and a TPA3110D2 (in blue snap top lid box). Second photo is the back side so you can see the nice curves that the foam core can make.
That speaker looks AWESOME!
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Old 11th December 2013, 02:13 AM   #2036
IG81 is offline IG81  Canada
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Quote:
Originally Posted by xrk971 View Post
I will try to get a measurement in next few days but first have something to try...
Remember the tractrix foam core horn I made a while ago?
Yeah I do, tried it much yet? I've made a Tractrix of my own as well a while ago. Paper petal variety:

Click the image to open in full size.

IG
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Old 11th December 2013, 02:19 AM   #2037
xrk971 is offline xrk971  United States
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Foam Core Board Speaker Enclosures?
Default Cochlear w/ Tractrix

BP1Fan,
If you think that looks good, check out what it looks like with a front tractrix horn - now were cooking with fire! The sound is very wide dispersion and makes the driver appear substantially louder - although I detect some horn coloration as this was not at all optimized.
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Old 11th December 2013, 02:31 AM   #2038
xrk971 is offline xrk971  United States
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Foam Core Board Speaker Enclosures?
Default Cochlear sealed TL- near cone measurements

IG,
I have some near cone measurements (1 in from cone). My setup uses a Panasonic WM61A capsule and the built-in mic input on the laptop which was designed for video conferencing etc so I think it has a low pass filter at around 5kHz. I am pretty sure the speaker has plenty above this sharp falloff. What I can measure though is very flat - as expected from a cochlear spiral with stuffing. There appears to be NO reflections whatsoever and the response is amazingly flat. The bump at 30 Hz is the hum from the HVAC. The drop near 330 Hz probably corresponds to the closed-ended TL length of 36 inches (1-Lambda of 312 Hz)? Look at how clean the impulse response is, and the low THD of less than -40dB, and the nice -20 to 20 deg linear variation in phase.

Click the image to open in full size.
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Last edited by xrk971; 11th December 2013 at 02:57 AM.
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Old 11th December 2013, 03:12 AM   #2039
MisterTwister is offline MisterTwister  Tibet
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xrk971, do you have impedance measurements from that speaker? thanks
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Old 11th December 2013, 03:18 AM   #2040
xrk971 is offline xrk971  United States
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MisterTwister,
No, I don't have a way to measure impedance - as it is a sealed alignment, I would imagine it is a single peak somewhere near the tuning freq of the TL at about 300 Hz.
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