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THAM 12 - a compact 12" TH

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Chaps View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Chaps Quote  Post ReplyReply Direct Link To This Post Posted: 18 December 2012 at 1:39pm
It have been a looong time since i last was in the garage for building subs (JBells SS15), but .. Now i'm back and excited to get started on something new.

The THAM12 looks very interesting to me. I was actually looking into finding some Danley TH-Minis, but they ended up being to expensive where i live. It looks to me, as the THAM12 is very close to the Danley design.

Anyway .. I was looking at your sims on different speakers and i stumbled across something that got me wondering ..

The B&C 12PS100 is rated very low in effeciency compared to for example the PD 12.SB30, when looking at the spec sheets.
The difference at 70Hz is about 7.5 dB.
That would normally make me go for the PD, even though the B&C is capable of handeling almost twice the power. This will only gain it 3dB in advantage anyway.

Now, when i see your simulations, they seem to be very close at 1W. Is there a simple explanation to this? Is the PS100 just a more suited driver and therefore have a bigger efficiency boost or? 
Can you tell anything about how they will behave at full tilt?

I am suspecting that the TH-Mini is using the PS100, so there must be a good explanation for that Smile

 Thanks in advance!

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Post Options Post Options   Thanks (0) Thanks(0)   Quote mobiele eenheid Quote  Post ReplyReply Direct Link To This Post Posted: 19 December 2012 at 12:01pm
PD States the test cabinet is a closed 975 liter box. B&C states the test cabinet is a 40 liter reflex tuned to 48 Hz. So two extremely different enclosures. You simulated those drivers in the same enclosure, which by the way is a cabinet that alters the efficiency of different drivers towards the same frequency response.
 
Both drivers are excellent horn/ bandpass drivers, tho different efficiency-wise (n0) and optimized for different frequency ranges.
 
In my experience, results when measured will be greater then simulated. Likely to happen is that the 12SB30 is percieved louder due to more output starting above 70 - 100 Hz. Whereas the 12PS100 will have more output below 50 Hz. All at the same input power.
 
For heavens sake lets not forget about power compression differences.
 
Best regards Johan
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Chaps View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Chaps Quote  Post ReplyReply Direct Link To This Post Posted: 19 December 2012 at 1:06pm
Thanks for clearing that up. Totally missed the different cabinets used for measurement.

The 12SB30 sounds compelling, as the box will be high passed around 50Hz, so no need for the driver to due well beneath that frequency. Much rather have a little extra output in the 70-100Hz region.
So frem specs and sims it lookes like the only real advantage of the 12PS100 is the capability of 700/1400 watts compared to the 12SB30s 400/800 watts.  Only a couble of dBs in difference for almost double the price.

I see though, that the PS100 is specified to +/- 8mm xmax (16mm in total) whereas the SB30 is 7mm. Anyone knows if PDs specs i also +/- ? If not, could the extra xmax be a great advantage of the B&C in this design?

Alot of questions, i know .. Bear with me Embarrassed
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Timebomb Quote  Post ReplyReply Direct Link To This Post Posted: 22 December 2012 at 9:15pm
The PD Specifies +/-7mm xmax (5mm overhang) 

How high are people running these cabs?  Anyone think hitting 200Hz is possible?  Im quite tempted to knock one together to find out...
James Secker          facebook.com/soundgearuk
James@soundgear.co.uk               www.soundgear.co.uk
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Post Options Post Options   Thanks (0) Thanks(0)   Quote lukam Quote  Post ReplyReply Direct Link To This Post Posted: 23 December 2012 at 12:45pm
Here is a measurement from my prototype 12'' tapped horn. It has the same folding as martinsson but a bit longer horn path and is a bit bigger. Loaded with 18sound 12LW1400 it takes 1400W without exceeding xmax. Simulations predict a lot more excursion than it is in reality. In this prototype I have a small resonance at 63hz that I'm trying to get rid of. The low extension sounds lower than the measurement predicts and I can boost it at 47hz and get alot more low end... for such a small box prety impressive.
I think you can get to arround 150Hz with the crossover before it starts to sound bad. 


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Post Options Post Options   Thanks (0) Thanks(0)   Quote mrloud Quote  Post ReplyReply Direct Link To This Post Posted: 16 January 2013 at 10:03pm
What are opinions for B&C 12TBX100 in tham 12?

Martinsson can U try it on your test to see diaghram...?

Thanks!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Chaps Quote  Post ReplyReply Direct Link To This Post Posted: 06 February 2013 at 10:59am
Finally .. I have two (almost) finished THAM12s loaded with PD.12SB30 Smile Thought i would share a pic.



Just needs grills and perhaps another layer of paint.
Only had them fired up for a few minutes so far, so can't really say much, but the sound quality was just great!
Have a gig on saturday with a lot of time to play around. That will be interesting Tongue


Edited by Chaps - 06 February 2013 at 11:01am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote supremesoundz Quote  Post ReplyReply Direct Link To This Post Posted: 06 February 2013 at 11:12am
Look good! Look so compact. Do you have any build pictures?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Chaps Quote  Post ReplyReply Direct Link To This Post Posted: 06 February 2013 at 11:24am
Originally posted by supremesoundz supremesoundz wrote:

Look good! Look so compact. Do you have any build pictures?

Thanks!

Build pictures will be uploaded under "New projects forum". Just need to get all the pictures from phone to computer. Will get them online this week, together with pics of them from my gig on saturday.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote t.geessounds Quote  Post ReplyReply Direct Link To This Post Posted: 07 February 2013 at 1:06am
nice
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tv00 Quote  Post ReplyReply Direct Link To This Post Posted: 15 April 2013 at 2:17pm
@ovidias I'm curious about your modified design, can you post how you did it?
I can see that you did more than making the design additional 5 cm longer, with this extra fold just before the driver.
I have had 4 pcs rcf lf12n401 laying around for ages, so I want to build 4 boxes for them!
-Additional LF extension would be nice, the design is so compact that adding a little extra volume is no problem.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kingkwak Quote  Post ReplyReply Direct Link To This Post Posted: 16 April 2013 at 8:18pm
What sort of weight do they come in at?
To much power? NEVER.
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