TH-18 Flat to 35hz! (Xoc1's design) - Page 3 - diyAudio
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Old 12th June 2011, 10:22 PM   #21
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ehh it starts falling off before 40hz...this is supposed to be flat to 35! (semi flat)
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Old 12th June 2011, 10:29 PM   #22
Djim is offline Djim  Netherlands
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Remember your own words :

Quote:
Originally Posted by m R g S r View Post
Now I am pretty sure that the point of this design was for 4 cabinets to be Flat to 35hz.....

Here is a sim for 4 cabs at xmax + with the 18 sound 2400 drivers...
Click the image to open in full size.
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Originally Posted by m R g S r View Post
I am doing it because I do want that extra 10hz that the ss15 doesn't have.

Last edited by Djim; 12th June 2011 at 10:38 PM.
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Old 12th June 2011, 10:37 PM   #23
hisense is offline hisense  United Kingdom
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Hi Djim,

Thanks for this - looks like i will have to try a pair of these..

Presume if these are run in close pairs this should improve the response below 40hz? Excuse the basic questions but how well do tapped horns take to eq being applied to extend response a little - do they unload the driver below tuning and x max will be the problem?

Thanks again,

Luke
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Old 12th June 2011, 10:50 PM   #24
Djim is offline Djim  Netherlands
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Quote:
Originally Posted by hisense View Post
Hi Djim,

Thanks for this - looks like i will have to try a pair of these..
Presume if these are run in close pairs this should improve the response below 40hz? Excuse the basic questions but how well do tapped horns take to eq being applied to extend response a little - do they unload the driver below tuning and x max will be the problem?

Thanks again, Luke
Hi Luke,
I'll try to explain as good as I can. Stacking multiple Tapped Horns will not lower the resonance of the design as HornResp predicts. But in this case the design limit (1/3 wavelength) is set out on 38Hz. So the response in stacks will get a boost at all frequencies above 38Hz but the 'knee' (point were the response drops) will never go below 38Hz in reality like some predictions suggest. So, there is no need to worry about Xmax. However, you will need a low-cut filter (same as high-pass) to prevent extreme excursion. The settings for this low-cut filter haven't been modelled yet.
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Old 12th June 2011, 11:06 PM   #25
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how does the BMS 15N840 fare in these sub 40hz designs? Good?
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Old 12th June 2011, 11:12 PM   #26
Djim is offline Djim  Netherlands
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Quote:
Originally Posted by hisense View Post
how well do tapped horns take to eq being applied to extend response a little - do they unload the driver below tuning and x max will be the problem?
Sorry luke, forgot to mention that EQ-ing doesn't make your amp grow bigger. I mean if you use a power amplifier that is able to produce 1500W you can boost whatever you like because the amp will never produce more than 1500Watts. Therefore in combination with the right settings for the low-cut filter the excursion will never get above safety levels.
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Old 12th June 2011, 11:33 PM   #27
Djim is offline Djim  Netherlands
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The Xoc1 TH18 is compatible with many 15" drivers as well. The disadvantage of using 15's is a slightly higher group delay. The BMS 15N840 (old model) seems to model well in a Xoc1 TH18. Of course you will need some eq (and low-cut filtering)


Click the image to open in full size.
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Old 12th June 2011, 11:35 PM   #28
hisense is offline hisense  United Kingdom
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Thanks for the info Djim, it all makes sense.

Looking fwd to creating some saw dust.. Will go for routed rebate contruction and brace as suggested.
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Old 12th June 2011, 11:52 PM   #29
Djim is offline Djim  Netherlands
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Looking forward to see the results!
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Old 13th June 2011, 02:45 AM   #30
tb46 is offline tb46  United States
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Hi Xoc1,

Just would like to say that I appreciate your efforts very much, and hope that you can provide more insights into box behaviour as in the Ansys pictures in Post #6/11. It looks like the bottom board was used as reference in the FEA simulation, and it would be interesting to see what it looks like turned (referenced) upside down, so that the whole mouth perimeter would be able to flex.

Anyway, great work, thanks.

Regards,
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