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Date: March 10, 2015 at 17:29:31
From: Dave, [c-73-35-42-214.hsd1.fl.comcast.net]
Subject: Help Porting a Cabinet


Thanks in advance to anyone who can help me out. I need some idea as to how to best make this work. I am going to build two compact low profile 2X8 subs. The interior dimensions of the cabinets will be 12x18x20 . This is the driver I will be using

• Nominal Diameter8"
• Power Handling (RMS)150 Watts
•
• Power Handling (max)300 Watts
• Impedance4 ohms
•
• Frequency Response30 to 200 Hz
• Sensitivity87 dB 1W/1m
•
• Voice Coil Diameter1.5"
Thiele-Small Parameters
• Resonant Frequency (Fs)30.2 Hz
• DC Resistance (Re)3.53 ohms
•
• Voice Coil Inductance (Le)1.76 mH
• Mechanical Q (Qms)5.86
•
• Electromagnetic Q (Qes)0.35
• Total Q (Qts)0.33
•
• Compliance Equivalent Volume (Vas)1.19 ft.ณ
• Mechanical Compliance of Suspension (Cms)0.53 mm/N
•
• BL Product (BL)10.1 Tm
• Diaphragm Mass Inc. Airload (Mms)52.5g
•
• Maximum Linear Excursion (Xmax)8.8 mm
• Surface Area of Cone (Sd)213.8 cmฒ
•
Materials of Construction
• Cone MaterialPaper / Kevlar
• Surround MaterialRubber
•
• Voice Coil Wire MaterialCopper
• Voice Coil FormerKaptonฎ / Polyimide
•
• Basket / Frame MaterialSteel
• Magnet MaterialFerrite
•
Mounting Information
• Overall Outside Diameter8.19"
• Baffle Cutout Diameter7.09"
•
• Depth4.23"
• # Mounting Holes8
I am looking for an f3 of 30hz. The problem is I need the ports to be in the front baffle. The baffle will be 12X18 so I don’t have a lot of space. My efforts produced either 2ea 3x15 round ports or 2ea 2x2x16 slot ports. Am I on the right track? How do you calculate triangular ports and is it true they always seem to tune lower than their simulations or formulas would suggest? I am also concerned about port honk, chuff, or whistle. Here is another thing I never found a real answer to; I always wondered, does the volume of the ports subtract from the cabinet volume? Anyway, no options on cabinet dimensions, just porting. Suggestions? Oh and thanks again to anyone who can enlighten me on this!

Moderated By: brian@diysubwoofers.org


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