Date: July 17, 1999 at 21:53:39
From: djk, [dip334.inav.net]
Subject: Re: Two 12" MTX drivers (200 watts each)

Date: July 17, 1999 at 20:04:02 From: Igor, [pm3-13-14.dial.stratos.net] Subject: Two 12" MTX drivers (200 watts each) Their model number is ( I am not sure which one is which so I'll give you everything written on here): on the basket: 12rd828 8 ohm 91 9213 on the cone: 3cf243 On the magnet: 21A673 I would like to build a nice subwoofer for a home theatre setup ( I have a subwoofer outlet on the back of my reciever). All I need is an amp ( $50-60). I am just a beginner, but can follow instructions very well. Also know how to work with wood. dk: The 12rd828 is the model number,9213 is the year and week it was made.Unfortunately I don't have that part number in my database.On the other hand there are many other models with similar numbers that will allow me to make an educated guess.A two foot cube(22.5x22.5x22.5" internal)will yield about 6.6 cu ft.If you want sonotube I would use a piece 24" dia by 30" long with double endcaps and a 14x14x7.5" plenum for mounting the drivers.This should give an F3 around 40hz(sealed)with a Qtc of between .6 and .8 with heavy fill.A simple filter added to the amp will make it flat to about 28hz.If you wanted to port it the box will need to be three times as big and you will need to measure the parameters.As to the amp Maplin makes a kit that is 175 watts for about $50,you will need a power supply from Apexjr for about $30,and figure another $20 or so for incidentals. djk