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Need suggestions for Open baffle Design

Rega

Kannan_madhu

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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-d2-AS15-X200_SP.pdf
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  • 0-SK-12FRX-Z_OM.pdf
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yogibear

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Ahuja FR is 12” and the bass drivers are 15”. You can stick to 18-20” wide baffles (my personal recommendation would be 24” if possible)

Initially you can use one 15” bass driver and later add one more driver if your bass amp can handle impedance dips down to 2 ohms.

You can experiment crossing around 140 to 100 hz.

Though Qts on bass driver is a little less. 7 would have been great but still very good choice of drivers and thinking as far as I can read about driver specs. (My phone refuses to open the pdf). Go for it.

Despite of using 18-20” wide baffles, adding one more bass driver would be very much beneficial but I would personally add them below the FR to keep FR at ear height. DIYers have added two more above FR making it a total of 4 each side resulting in incredible soundstage and dynamic bass.

Once you run the FR unfiltered, you will never want to put anything before that though my combo had always been FR plus Tube amp.
 

yogibear

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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.
 

Kannan_madhu

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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
 

yogibear

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High Qts on the FR will help you cross lower. I prefer a Qts of arpund 0.7 on bass drivers as well. Qts nearing 1 is preferred by some.

Ideally for an OB bass driver I would prefer, Qts 0.7 to 1, Fs 40 Hz or lower, acceptable Xmas, 16 ohm impedance, 15” or larger and 95 dB or more the better.
 

Kannan_madhu

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Last edited:

Naveenbnc

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Isnt that a boxed design ?
yes that was a boxed design, the only coincidence being Ahuja SK 12 FR + a 12" bass driver.
Our FM DrKrack made OB with Ahuja SK 12 FR, and they sound great for the price. I was lucky to listen them.
 

Hari Iyer

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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.
 

Hari Iyer

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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.
 

Kannan_madhu

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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.jpg as 200 ts1.jpg
 
Last edited:

yogibear

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@hari.
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.

Hari. Please help here as you are more versed with this software.
 

jls001

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Please study the Manzanita OB design too since you're interested in OB.
 
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