Lab 12 Based Offset Driver - Mass Loaded - Transmission Line (OD-ML-TL) Design by Bj - Page 17 - diyAudio
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Old 12th May 2013, 12:23 PM   #161
Zero D is offline Zero D  United Kingdom
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when the girl feels like dancing
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Old 12th May 2013, 12:49 PM   #162
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Old 12th May 2013, 12:52 PM   #163
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@ DrDyna

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Old 12th May 2013, 09:21 PM   #164
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Lol!
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Old 13th May 2013, 06:31 AM   #165
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Funny stuff their Dr Dyna!

I have been trying to translate tb46's hornresp data into an enclosure but so far am failing miserably.

Can anyone assist? Thanks, Steve
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Old 13th May 2013, 12:25 PM   #166
DrDyna is offline DrDyna  United States
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Funny stuff their Dr Dyna!

I have been trying to translate tb46's hornresp data into an enclosure but so far am failing miserably.

Can anyone assist? Thanks, Steve
Oh, the TQWT? If it was me, I'd either build it in one tall peice, so it essentially looked exactly like the schematic looks in hornresp, or fold it over once backwards, then loop the mouth back around so it ends under the driver.

Edit: A crude sketch.
Edit2: Driver position should be higher, but, I think that's the general idea.
Attached Images
File Type: jpg tqwt sketch.jpg (17.2 KB, 228 views)

Last edited by DrDyna; 13th May 2013 at 12:36 PM.
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Old 13th May 2013, 12:41 PM   #167
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The speaker should be mounted 85cm or a third way up the line path.
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Old 13th May 2013, 12:47 PM   #168
NWCgrad is offline NWCgrad  United States
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Thanks, I had thought that's how it would look but was having doubts.

Modeled in Hornresrep and compared to the OD-ML-TL design and it is almost exact on all parameters (SPL, cone excursion, group delay, etc). Also compared to a sealed design (88.7 L, Qtc = 0.605) and at maximal cone excursion the sealed was down in SPL until 10.5 Hz, at 15 Hz the sealed was down by 6.5 dB and from 20-40 Hz was down an average of 9.@ dB (max - 11.7 dB@20 Hz; min - 6.3 dB@40 Hz). From 40 Hz to 120 Hz the sealed was down by an averagebof 3.5 dB.

Looks like tb46's little TL may be a cool option for my HT.
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Old 13th May 2013, 02:25 PM   #169
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Originally Posted by DrDyna View Post
Oh, the TQWT? If it was me, I'd either build it in one tall peice, so it essentially looked exactly like the schematic looks in hornresp, or fold it over once backwards, then loop the mouth back around so it ends under the driver.
For [sub] bass duty [<120 Hz], just folding the long ones in half and either spacing it up for bottom firing or cutting out the terminus [mouth/'vent'] in one or more sides is fine. Also, IME there's more performance advantage to mounting the driver at the extreme closed end ['top'] to maximize boundary gain/negate floor bounce regardless of what a typical sim indicates.

GM
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Old 13th May 2013, 06:16 PM   #170
NWCgrad is offline NWCgrad  United States
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Here are my initial efforts for developing an enclosure for the model provided by tb46 (see attachment). I think the unfolded is pretty accurate, but somehow my calculated volumes did not perfectly match the Hornresp data from which the parameters were taken. Error is probably because I converted to Imperial measurements instead of working in metric.
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File Type: jpg tb46 Hornresp Design.jpg (282.4 KB, 214 views)

Last edited by NWCgrad; 13th May 2013 at 06:19 PM. Reason: typo's
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