Reply to thread

Message: <blockquote data-quote="PV Audio" data-source="post: 2394982" data-attributes="member: 554493">Okay, here are the main box formulas, courtesy of DIYsubwoofers.org :Vb = 20*Qts^3.3*VasFb = (Vas/Vb)^0.31*FsF3 = (Vas/Vb)^0.44*FsdBpeak = 20*LOG(Qts*(Vas/Vb)^0.3/0.4)Vb = net box volume (litres)Fb = box resonant frequency (Hz)F3 = -3dB frequency (Hz)dBpeak = maximum peak or dip in system responseVas = Equivalent air compliance (litres)Qts = total Q of the driver at its resonant frequencyFs = resonance frequency of the driver (Hz)Dv = internal diameter of port (cm)Lv = (23562.5*Dv^2*Np/(Fb^2*Vb))-(k*Dv)Dv = port diameter (cm)Fb = tuning frequency (Hz)Vb = net volume (litres)Lv = length of each port (cm)Np = number of portsk = end correction (normally 0.732)The value for k, the end correction, can be fine-tuned by using the following values to derive the appropriate end correction figure for each end of the port, then adding them togetherFlanged End: 0.425Free End: 0.307e.g. if both ends were flanged,k = 0.425 + 0.425 = 0.850if one flanged, one free,k = 0.425 + 0.307 = 0.732if both ends were free,k = 0.307 + 0.307 = 0.614Normally, k=0.732 is assumedSlot PortsIf you wish to use a slot port, first determine the diameter of a round port that has the same cross-sectional area as the slot. The following equation can be used to do this:Dv' = 2*((W*H)/pi)^0.5where,Dv' =  diameter of equivalent round portW = width of slotH = height of slot</blockquote>

Top