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Old 25th October 2007, 03:29 PM   #21
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Hi GM,

I am using a helmoltz resonance calculator and it definately says that you need to double the vent length and area for the same tuning frequency for double the cabinet volume (which you would need to do for 2 drivers). Where am I going wrong then? Is this not true for MLTL?
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Old 25th October 2007, 04:29 PM   #22
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Greets part deux!

I don't know what you may be doing wrong, probably nothing other than needing to use a different calculator , which BTW will typically calc a too long vent in a MLTL since it doesn't factor in the MLTL's high aspect ratio TL loading on it, making it shorter for a given Fb WRT a simple golden or acoustic ratio cab. For best accuracy you'll need to use MJK's MathCad software or probably AKABAK. There may be others, but for sure all the free mainstream box programs I'm aware of can't do it.

Anyway, let's look at it this way and see what your program calcs...... with 2x the drivers, Vb and the same Fb, input a single vent of 2x the area of one (i.e. original diameter*~1.4142) and you should get a slightly shorter vent length than the one it calcs for the original single driver alignment. This is due to less friction compared to using two of the original diameter vents. If it does, then how can using two of the original diameter vents be twice as long?

GM
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Old 25th October 2007, 06:10 PM   #23
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Thanks GM. I will try one of the calcs you recommend and start from scratch.
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Old 28th October 2007, 07:58 AM   #24
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Quote:
Originally posted by keladrin
helmoltz resonance calculator and it definately says that you need to double the vent length and area for the same tuning frequency for double the cabinet volume (which you would need to do for 2 drivers).
Does the calculator account for 2 drivers?

dave
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