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Blaupunkt 12" for under  - 8 of these good for an infinite baffle build?
Blaupunkt 12" for under  - 8 of these good for an infinite baffle build?
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Old 31st March 2019, 08:15 AM   #11
googlyone is offline googlyone  Australia
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Blaupunkt 12" for under  - 8 of these good for an infinite baffle build?
Nothing in the above gives any indication of Xmax other than assumption - unless I have gone blind. (Which I seem to do on a regular basis

This is super critical for infinite baffle, and indeed any serious sub work.

Does someone have this information?
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Old 31st March 2019, 09:49 AM   #12
basreflex is offline basreflex  Spain
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the fact that the airchamber under the spider is ventilated makes that there is no air forced along the voicecoil, minimizing aircoooling.
it is difficult to estimate the magnet airgap width. the airgap length seems large to allow for production tolerances and cone torque/twist. the winding height could be estimated from this video being the scorched tainted paper voicecoilformer.
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Old 31st March 2019, 02:38 PM   #13
bjorno is offline bjorno  Sweden
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Quote:
Originally Posted by googlyone View Post
Nothing in the above gives any indication of Xmax other than assumption - unless I have gone blind. (Which I seem to do on a regular basis

This is super critical for infinite baffle, and indeed any serious sub work.

Does someone have this information?
Hi googlyone,All

I wrote:
Before any conclusions can be made when eyeballing this Driver: Do a consistency check:
xmax is around 12.5 mm, Sd is ~509 cm^2(506 if calculated) but the parameters are all inconclusive and doesnt match like fs= 32 Hz ,no way: but could be 42-43 Hz . Further is that Exm is missing, probably by purpose to misslead./b

Isn't this Information you could base a Design? You hang up your Serious? consideration/assumption that an IB only could work properly if a single Parameter like xmax is the crucial Parameter when the most important indication is that of the given Parameters are corrupted.

I never assume, I do educated guesses like I've Posted: So why didn't you check my findings?

I gave you an indication of your ‘’Xmax’,fs and Sd’ and that is much more than ‘Nothing ‘

Here is what I based my guesses on, for the given Driver:*

b

*
Blaupunkt_GBW120_SD_Xmax.JPG

Blaupunkt_GBW120_scrutinized_A.JPG

Blaupunkt_GBW120_scrutinized_B.JPG
Attached Images
File Type: jpg Blaupunkt_GBW120_SD_Xmax.JPG (562.8 KB, 186 views)
File Type: jpg Blaupunkt_GBW120_scrutinized_A.JPG (352.6 KB, 181 views)
File Type: jpg Blaupunkt_GBW120_scrutinized_B.JPG (387.5 KB, 179 views)
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Old 30th July 2019, 06:18 PM   #14
Aaron DIY is offline Aaron DIY
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I measured the Fs of the GBW120. Fs= 39Hz +or- 0.5Hz. Sorry to muddy the waters of these specs further. My credentials are: I am a compete noob at audio. This is my first build.

Measured the Fs using a 10ohm resistor in series with driver in free air (no baffle if that matters). Used a o-scope to measure the voltage drop across the resistor while feeding a sine wave sweep through the system. Narrowed it down, then did progressively smaller and slower sweeps. Lowest voltage=Fs. Did I get it right?

Only used the o-scope because my multimeter's precision is poor at low ac voltages.

Side note: these drivers live up to their price point. The basket to cone is glued off axis a few degrees. The center cover thingy does not come close to lining up with the mounting holes.

Thanks to Bjorno whose educated guesses have helped a lot. The box I built before receiving the driver will still work ok despite Blaupunkt's BS
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Old 18th August 2020, 01:06 AM   #15
floatadventure is offline floatadventure  Sweden
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Thank you everyone so much for the replies and the info. I read everything but I also ended up buying 8 of them and building a speaker. It doesn't have the deep end response I wanted. I have a lot to learn about speakers. I'll post a picture of the build here tonight.
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Old 19th August 2020, 07:07 PM   #16
BP1Fanatic is offline BP1Fanatic  United States
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Build this BP6P with the Blau's!

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Old 19th August 2020, 08:26 PM   #17
Brian Steele is offline Brian Steele  Grenada
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There is a measurement process error in that article, which likely explains why the measured low end response seems to be higher than what Hornresp predicts, rather than vice-versa. Do you see it?
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Old 19th August 2020, 08:45 PM   #18
BP1Fanatic is offline BP1Fanatic  United States
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The fact he didn't measure outside? He did state close-mic above this pic.

Click the image to open in full size.
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Old 19th August 2020, 08:47 PM   #19
BP1Fanatic is offline BP1Fanatic  United States
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Also, the enclosure is not on the ground.
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Old 19th August 2020, 08:52 PM   #20
Brian Steele is offline Brian Steele  Grenada
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Nope.

Close-miking a 6th Order Parallel BP system that way should work out well - if the vents are the same CSA. That's not the case here.
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