Need suggestions for Open baffle Design

Kannan_madhu

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Location
Thrissur, Keralam
I have read very good feedback on Ahuja SK 12 FR full range driver here and want to make one open baffle speaker with this driver. Since the bass response will be less i would like to add a helping woofer my initial plan is to build some thing like PA Trio as i dont want huge baffles due to space constraints. Amplification part plan is to go for a class AB or A for the full range with out filters and Class D with sub filter . How good will be the sound quality if i use comparatively smaller baffle like trio ? will there be harshness in mid range ? And can i get sufficient base if i use a PA driver like Ahuja AS15 200 or two of them( FR curve shows response above 90db till 40hz ) ?


Ahuja AS 15 200
Power Rating
200W RMS
Nominal Diameter
380 mm (15”)
Nominal Impedance
8Ω
Sensitivity (1W/1m )
98dB
Magnet Weight
1.54kg
Resonant FrequenceY (Fs)
45Hz
DC resistance (Re)
6.0Ω
Electromagnetic Q (Qes)
0.58
Mechanical Q (Qms)
9.6
Total Q (Qts)
0.54
Compliance Equivalent Volume (VAS)
115 Litr
Surface Area of Cone (Sd)
830cm2
Reference Efficiency (ηo)
2.1%
Voice Coil
2.0”
Overhang (Xmax)
3.5 mm
Moving Mass (Mms)
73gm
BL Product (BL)
13.4TM
Overall Diameter
385 mm
Depth
165 mm
Baffle Hole Diameter
355 mm
Bolt Mount Diameter (PCD)
373 mm (8 Bolts)
Weight
4.9kg

may be some thing like this

images
 

Attachments

  • ahuja as15.jpg
    ahuja as15.jpg
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  • 0-SK-12FRX-Z_OM.pdf
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If Ahuja has a similar bass driver but with higher Qts and 16 ohm impedance, then the OB can compare with the best of OB projects... and at a fraction of cost.
SK 15FR has qts 0.77 but its a fullranger
sk15frx.jpg


i think there is no model which offers higher q in mid woofer range
 
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I have done simulation of both the Ahuja 12" and 15" FR drivers in the Basta simulator with the published parameters. I have noted a roll-off of around 150Hz with them. Dont expect much bass with them if you are using them in OB. You will need to compliment them with a TL or other subwoofer to get the low end lift. I will try and post the simulated response if i am able to locate the images in my laptop.
 
I hope you have gone through Ravindra Desai design with Ahuja12" FR and Iwai 12"
As far as i know Ravindra Desai use a Box simulator (WinIsd) for box simulation which is a very basic simulator. You will need advance simulators like LA, Mathcad or Basta to give a proper simulation results.
 
I entered the given values in ahuja website to basta and this is what i got ,but i dont know if i have made any errors or missed some values as per basta user guide in the first set of driver values we have to enter three values rest will be calculated by software. But the calculated values were different from those were given in the website. And where should i place the mic in simulator ?
ahuja as 200 ts.jpgas 200 ts1.jpg
 
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Hello all,

Here is another article from a person who needs no introduction.
In simple language, he lets you know what you are getting into when you are DoingItYourself.

I have no experience in open baffles and so I will not be participating in this actively.
But hopefully some day, I'll probably team up with @yogibear to do an open baffle design.

Till then you all have fun with this: http://www.linkwitzlab.com/conclusions.htm

Regards,

Ravindra.
 
Thanks for the suggestions. I went through the suggested pages . Can low qts be a problem in active amplified system ? can some one help me with the simulation ?
 
I can suggest a couple of alternate dipole OB bass designs and they probably cannot be simulated, but they will surely click with the Ahuja bass driver. However, I need to know, how big your room is and what active crossover do you have for active amplification ?
Room is around 9m ×4.5 m right now I have a Linkwitz Riley crossover crossed at 2k . But my plan was to power the fullranger directly from a class a or class ab and use class D Sub amp with frequency selectable low pass filter . I have this one with me

Aiyima DC12-24v TPA3116 Subwoofer Amplifier Board Support 100W Bass Output

I also have lm3886 and lm1875 boards in hand so I can try that too
 
It’s a sad truth that the ratio of OB worthy drivers is 1:10 compared to all other designs and OB bass is hardest to tame. )

I shall go ahead and say the ratio is 1:10000 if you are considering a single full range driver for OB duty. You may need to consider field coil speakers for this requirement imo.
 
@Hari Iyer ,

@Kannan_madhu needs your help.
I just thought I'll repost since @yogibear actually addressed another Hari and so you could have missed this one, genuinely.

Also, as stated in post # 13, kindly share your simulation results.
I am eager to learn from the young and the dynamic generation.

Regards,

Ravindra.

Will try and post Abuja FR driver simulation by tomorrow.
 
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