12" Tapped horn

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JD, I have to admit this PD 12SB30 driver has more in it then MTH-30 can deliver. As you can see in JDK’s hornresp that 38Hz is possible although at the cost of max SPL (the Xlimit of the cone will be reached earlier) and a much bigger box.
Like always you have to choose between the max SPL of 130dB for the 53Hz MTH-30 design or a max SPL of approximate 124dB from DJK’s 38Hz version. The MTH-30 has an internal volume of about 135 Litre and DJK’s idea will need an internal volume of about 210 Litre.

Edited by Djim69 - 29 August 2010 at 6:18pm

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Djim69 Members Profile Send Private Message Find Members Posts Add to Buddy List New Member Joined: 29 August 2010 Location: Benelux Status: Offline Points: 6	Post Options Post Reply Quote Djim69 Report Post Thanks(0) Quote Reply Posted: 29 August 2010 at 6:08pm
	JD, I have to admit this PD 12SB30 driver has more in it then MTH-30 can deliver. As you can see in JDK’s hornresp that 38Hz is possible although at the cost of max SPL (the Xlimit of the cone will be reached earlier) and a much bigger box. Like always you have to choose between the max SPL of 130dB for the 53Hz MTH-30 design or a max SPL of approximate 124dB from DJK’s 38Hz version. The MTH-30 has an internal volume of about 135 Litre and DJK’s idea will need an internal volume of about 210 Litre. Edited by Djim69 - 29 August 2010 at 6:18pm

_djk_ Members Profile Send Private Message Find Members Posts Add to Buddy List Old Croc Joined: 23 November 2004 Location: United States Status: Offline Points: 6002	Post Options Post Reply Quote _djk_ Report Post Thanks(0) Quote Reply Posted: 30 August 2010 at 9:38am
	Cone motion has to increase at a 12dB/oct rate. 53hz * 0.707 (one half octave) = 37.5hz Therefore the maximum output for a given cone displacement must be 6dB less for a half octave of bass extension. Note: You must be comparing apples with apples, ie: tapped horn vs tapped horn, or sealed box vs sealed box. A 2 cu ft 2nd order sealed box with an F3 of 30hz can only be 0.18% efficient (84.55dB). A 2 cu ft 4th order vented box with an F3 of 30hz can only be 0.36% efficient (87.56dB). A 2 cu ft 6th order vented box with an F3 of 30hz can only be 0.90% efficient (91.54dB).
	djk