Lab 12 Based Offset Driver - Mass Loaded - Transmission Line (OD-ML-TL) Design by Bj

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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.
 

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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.
 
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 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
 
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. :eek:
 

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  • tb46 Hornresp Design.jpg
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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. :eek:

Are the volumes too high? It might be the fold right at the bottom, you'd probably have to manipulate that last turn (bottom back) to keep the taper even.

Edit: Something like meow.
 

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  • tb46 Hornresp Design.jpg
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Single fold = 51". Double fold = 25.5".

I'm not smart enough to figure out a single fold, let alone double fold.:confused:

Attached is my latest stab (only took about 6 hours).

I have the L12 and L23 lengths correct, not positive about the volume. However, I can not figure out how to make the L23 fold twice to reach the front of the enclosure (based on Oliver's drawing from the link of page 14).

Hopefully one of the pros will jump in and assist with the folding.
 

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  • OD-TL_tb46_NWCgrad folding attempt #2.jpg
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Aaargh, spent way to long today on this and still cannot get it how I want it.:sad: It's driving me nuts (well nuttier, my wife already thinks I'm nuts).

Hah, yeah, I tried to fold one once, I'm sure there's some tricks to it that once you learn make it easier.

One of these days, maybe Oliver will make a youtube video in fast-motion of how he does it with AutoCAD :)
 
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