desktop TL with 3" driver (with real bass)

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Henkjan

Henkjan

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Joined 2006
juoiga.nl
#1
I already mentioned it in another thread: I just completed a pair of desktop TL's using the Omnes Audio BB3.01 (is Tangband built designed by BPA).

I had a few starting points for the design:
- same baffle as the CT222 (a small BR with this driver)
- real bass
- easy to build

so I started the design using the allignment tables from MJK (weidok and I made a nice excel sheet that automates this) and the allignment from that (a 1:10 taper, driver at 1/3 of the line, tuning 55Hz) was the starting point for the Mathcad sheets. the 'driver offset' sheet gave very promissing results, so I made a sketch, and entered that into the sections sheet. just some tweeking and the results were imho excelent. I optimised the stuffing so I could use 1 sheet of Sonofil for each box
 

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#2
so, building it was fairly easy, just the normal 6 pieces + 1 extra... I applied the same notch filter as for the original BB3.01, so I could do without measurements this time, and soon I could start listening...

I wa stunned. the bass was amazing, most I have heard from this size of driver ever. (in a larger room the bass is somewhat less I found out later) even percussions sounds good, a accoustic bass sounds like a big instrument, etc.

I decided to do a combination of vineer and paint for the exterior to finnish them off, se the photo
 

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#3
on the stuffing: most of it goes into the closed end. the area around the driver remains empty, and only some 4 grams go into the open end. bass output is rather sensiive for the stuffing in the open end, so if you experiment use small changes...
 

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#5
a drawback of this design is that it will not fit every desktop, due to the large depth.... so why not flip it on it's end and move the driver a bit... this results in a 40cm tall and only 22cm deep box. would fit nicely next to any decent sized LCD screen or TV... so I modified the mathcad sections sheet, and the results were very similar to the original.. just a dB or so in the ripple, nothing more..
 

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#10
purplepeople said:
I tried something similar for my own desktop about 3 years ago. It was tuned to 100 Hz to match the Tangband driver.

http://www.diyaudio.com/forums/showthread.php?postid=620682#post620682

Does the line tuned much lower than the driver Fs really have that good a response or does it create ripples?

🙂ensen.
Click to expand...


I have the same driver TB W3-593 looking for a small cabinet with some bass, details on your build will be appreciated if the sound was good.

gychang
 
#11
Henkjan said:

I had a few starting points for the design:
- same baffle as the CT222 (a small BR with this driver)
- real bass
- easy to build

so I started the design using the allignment tables from MJK (weidok and I made a nice excel sheet that automates this) and the allignment from that (a 1:10 taper, driver at 1/3 of the line, tuning 55Hz) was the starting point for the Mathcad sheets. the 'driver offset' sheet gave very promissing results, so I made a sketch, and entered that into the sections sheet. just some tweeking and the results were imho excelent. I optimised the stuffing so I could use 1 sheet of Sonofil for each box
Click to expand...


what mods maybe needed for TB W3-593, if any? BSC circuit?

gychang
 
#12
purplepeople said:
Does the line tuned much lower than the driver Fs really have that good a response or does it create ripples?
Click to expand...
you can see the sim in the opening post... flat enough for ya ? 😎 the combination of a strong taper and the stuffed closed end does the trick.

I think this basis (~1:10 taper and 80-85cm line length, lots of stuffing in the closed end) might work with other TB drivers as well. but I expect you'll want to change the BSC somewhat.

also with the box upright, the BSC will be slightly different (I suggest to use the one for the Needle with the BB3.01 (0.56mH, 5.6 ohm, 5.6uF) in that case, BSC for the Ct222 is 0.39mH, 10uF, 5.6ohm)

the BB3.01 is a polyprop cone wide range made by TB for Blue Planet Accoustics, so availability is limited to germany and the surrounding countries. unless you don't mind paying 22 euro's for shipping them to Australia... (just PM me if you want a pair, they are very fine FR drivers, almost as good as the Vifa's for just over half the price, and 4 ohm)
 
#14
Henkjan said:

you can see the sim in the opening post... flat enough for ya ?
... I think this basis (~1:10 taper and 80-85cm line length, lots of stuffing in the closed end) might work with other TB drivers as well.
Click to expand...

Interesting... I had an idea for a 2.1 system using an autosound coaxial, but now with the lower response from the aggressive taper, it looks like I might be able to leave out the single woofer.


gychang said:



I have the same driver TB W3-593 looking for a small cabinet with some bass, details on your build will be appreciated if the sound was good.

gychang
Click to expand...


I don't know how the speakers are set up now. When I left Vancouver, I gave them to my cousin who is an audio engineer with one of the local multimedia technical schools there.

When I had them, I used with my office computer. The forward port is because there are no wall in the open plan office. The low port allows some LF reinforcement from the desk surface. The amplifier was ripped out from some old PC speakers that were going to be discarded by someone else.

The line is about 23 inches long with 3:1 taper as per the MJK alignment tables. There is no BSC. Instead I used the Media Player equalizer to attenuate everything from >1 kHz by 6dB. The 1kHz slider was set to -3dB and all the lower were set to 0dB. It's actually really effective. When I really wanted to impress the colleagues, I would turn up the SRS TruBass for that fake sub effect.

The project was designed to be really cheap. It uses common pine dimensional lumber from the home improvement store. The sides cut from are 1x10 (19mm x 240mm). Front, back and all the interior panels are 1x4 (19mm x 90mm). Approx 40 drywall screws and no glue since it is small and the multiple panels make it very rigid. The stuffing is polyester blanket I found at the dollar store and fills from the closed end past the driver to the back. The last 1/3 of the line is free air.

My cousin almost cannot believe that I made them from cheap wood, cheap screws and a $1 blanket. Morever, the drivers were purchased at a discount for about $15 each. I'd say the total cost was just under $50.

I'll dig around and see if I still have the 3D model. If I can find it, I'll add some dimensions and re-post it for you.

🙂ensen.
 
#15
Sorry to bring up an old thread, but I just got a pair of the TB W3-593's for a desktop speaker project for a friend. This box looks like a simple, small-ish solution!

I'd like to possibly change the shape of the box, possibly making something curvier. What basic guidelines should this cab novice follow?

Thanks- Kent
 
#18
kstlfido said:
I don't really know, just something that steps away from the cubic form, yet easy to construct. I thought of a cylinder shape. I have some 8" (20cm) dia. cardboard tubing to test it out.
Click to expand...

http://homepage.mac.com/planet10/TLS/projects/sampson/images/Babysnake_strike.jpg

This guy has a number of projects using PVC. I suppose it depends on how adventurous the design would be and for whom it's being built. These are just fun and would create conversation as computer speakers etc.
 
#19
Hi guys,

I got plenty of paper tube 160/150mm. Henkjans box has 186cm² area , my tubes have 176cm². Very close, so I will steal his alignment 😎.

Building "Tube-Needles" is almost impossible, but with these short TLs it can be done, no, will be done...

Joe
 
#20
Thanks for the help, folks. Sounds like 8" (203mm) dia. is too wide. Which is good, i'd like it to be a tad thinner. A 6" (152mm) tube should do OK, 181cm².

Attached is a rough idea. I have these brass endcaps with 6 bolt pattern. They would look cool!

-Kent
 

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