Concept, Beolab 11 style isobaric sub using Ikea Blanda metal bowls. - Page 3 - diyAudio
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Old 28th June 2012, 01:46 PM   #21
bjorno is offline bjorno  Sweden
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Quote:
Originally Posted by Studio Au View Post
Really wish I knew what I was looking at?

Doesn't seem like a very smooth response in any of the graphs.
You're kidding or are totally unaware of Speaker engineering and how to interpret HR simulation graphs. You must (In head) extrapolate HR to include damping materials..in the enclosure volumes.

b
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Old 28th June 2012, 02:13 PM   #22
bjorno is offline bjorno  Sweden
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Adding a picture where the ported enclosure is (sub) filtered at 80 Hz using LR4 LPF:
The small ripple seen in the off-band will totally disappear when damping materials are added.

b
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Old 28th June 2012, 04:54 PM   #23
bjorno is offline bjorno  Sweden
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Quote:
Originally Posted by bjorno View Post
..The small ripple seen in the off-band will totally disappear when damping materials are added.
This fact can be seen here:

b

PS: My posting to this thread was not in the first place to show my weird 'Bowl'
design but the supplied 'rookie' calculations of the consequences when
using the TangBand driver in different configurations.
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Old 28th June 2012, 11:15 PM   #24
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Quote:
Originally Posted by Studio Au View Post
50 Uk $45 Us. Grrr

Look good though, would they work well in a sealed 11L enclosure?
I run mine in a 11L ported box, 2" tube, 11" long, light stuffing in the port. They hit 40Hz clean but there's nothing useful below ~35Hz.

The thing with projects like this is you very quickly hit the limitations given by Hoffman: small size, bass extension, efficiency. Pick any two.

The Tang Band driver (for me) represents a decent compromise: you get to use small boxes. They'll go to ~40Hz at decent SPLs (a pair was enough for a room 20m by 10m playing Metallica and some others at decent levels), but you'll need plenty of clean power to get there.
At excursions passing 5mm one-way, distortion begins to increase. Its clearly audible on test tones (especially below port tuning), but on music it's not too bad. Even so, if you're repeatedly running these drivers to that sort of excursion, I'd recommend the use of larger drivers.

We use my speakers for movies - tried Terminator, Resident Evil, etc. In a UK-sized living room, a pair of these drivers will hit cinema levels. Put them against a wall for even more output. An infrasonic filter should be considered essential, for sealed or ported designs: these drivers will not go properly low, nor should they be asked to.

Using a sealed cabinet means you'll likely hit output limitations earlier than ported boxes, however...

- despite being a teenager (you know what teenagers can be like with volume), I haven't managed to cause these drivers any great strain. They cope with movies and everything else as well as I could ask.
- because they're in a dedicated subwoofer, you can stick it in a corner or against a wall. I don't have that option (they're built in to the main cabinets), so you'll likely gain some SPL there.
- the slot loading will also, I suspect, gain you some extra output.

Methinks you'll be fine with a pair in sealed cabinets, but if you want a little more output, a pair of

W5-1138SMF - TB speakers 5 inch paper cone subwoofer - Europe Audio

Will have more cone area than a single 6".
Alternatively, perhaps look at the 8" drivers and Linkwitz Transform circuits

Chris
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Old 29th June 2012, 06:24 PM   #25
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This design is always going to use two drivers.

I had a big 15" pro woofer, held up by a big spike running open with no baffle, really liked the sound, just supper low level bass re-enforcement. I'd like to see how a properly designed small(ish) sub will work.

I think I'll wait until I eventually build my large horn system before I approach the 15" woofer route again. Small subs for now.

Thanks for all the graphs. I will try and study them.
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Old 29th June 2012, 07:29 PM   #26
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I meant two drivers per side of the design, 4 drivers total. 4x5"s would give more output than 2x6"ers.

Chris
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Old 29th June 2012, 08:33 PM   #27
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Now were talking...
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Old 29th June 2012, 10:50 PM   #28
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Ran some quick numbers using the older version of the 5" woofer (the specs of the newer one are similar).

4 of those drivers (total) in a 22L (again, total) sealed cabinet without slot loading would give a Qtc of 0.75 (slight rise in response - nothing to worry about).

Keeping excursion sane at a mere 5mm one-way would give a SPL of 98dB at 40Hz. Remember winISD gives figures for half-space.

I've done a comparison between 4x 5" drivers sealed vs 2x6" drivers ported.

With a suitable highpass added to prevent the drivers bottoming out below port tuning, the pair of 6"ers appear to win this one - see attached. Note the Xmax for the 5"ers are ~9mm, so both systems are being pushed hard here.

If you're willing to go ported, the 6"ers would better use the cabinet volume IMHO.
If you want to stay sealed, the 5"ers will give decent performance. You might like to read this - rather useful information about getting the most out of a sealed subwoofer.

Chris
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File Type: png SPL.png (33.2 KB, 228 views)
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Old 29th June 2012, 11:45 PM   #29
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Thanks for all the effort.

Ported is always an option, where would you put it?

I'll try and draw up some sketch up 3d models of certain setups as aesthetics will always play a role.

2x6"s ported, can this design be modified to make it better?

Last edited by Studio Au; 30th June 2012 at 12:05 AM.
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Old 30th June 2012, 09:44 AM   #30
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You could (for a clean aesthetic) fire the ports into the slot between the two halves, but I've no idea how that'll affect the output.

Note: to avoid chuffing, a 2" port should be used. This comes to be around 11" long, so a 90 degree bend may be needed to fit it in the small space.
You could go for a smaller diameter port to then reduce the length, but chuffing might become an issue.
The author here seems to think you'll be okay:
Cerberus

Quote:
Originally Posted by Studio Au View Post
2x6"s ported, can this design be modified to make it better?
Better in what way?
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