| 4 Pi Design Questions [message #61737] |
Sun, 17 January 2010 22:09  |
Nichol1997
Messages: 21
Registered: December 2009
Location: Virginia
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Chancellor |
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Wayne,
I have been modeling the bass response of your 4 Pi design using the JBL 2226H drivers in WinISD. I have calculated the net volume of the enclosure to be approximately 2.74 cubic feet. Given your port dimensions and the net volume of the enclosure, the tuning frequency appears to be 27 Hertz.
I would like to alter the response curve by making a slightly larger enclosure (3.6 cu ft) and raising the tuning frequency to 40 Hertz. This can be achieved by increasing the height of the enclosure by 7 inches. I would like to keep the port on the front baffle but move it to the bottom of the enclosure. From your previous posts it seems that standing waves may become an issue, is this correct?
Do I also need to worry about midrange frequencies escaping from the port and canceling with the front-wave of the speaker?
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| Re: 4 Pi Design Questions [message #62255 is a reply to message #62252] |
Sat, 03 April 2010 09:32  |
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Wayne Parham
Messages: 18793
Registered: January 2001
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Illuminati (33rd Degree) |
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I use Dayton capacitors sometimes, yes. If a person orders a standard crossover with no upgrade options, they will have Jantzen, Erse, Solen or Dayton polypropylene caps.
But as for the Jantzen 22uF capacitor, you can use it where the schematic calls for 20uF. If we get an order for Z-Caps, that's what we use. We use Z-Standard caps in all positions except for the 0.47uF part, which is a Z-Superior. Not because I think it needs this, but because the 0.47uF size isn't available in the standard line. If someone was interested, we would be happy to use Z-Superior parts in all positions for a little extra cost, but we don't stock them. Most people that want the high-end caps want Auricaps.
As a related aside, 16Ω resistors are substituted with 15Ω parts and 12.5Ω resistors are used in place of 12Ω when Mills resistors are chosen. We use Dayton non-inductive 10 watt resistors for the standard option, Mills 12 watters for upgrades. The Zobel resistor is a non-inductive 100 watt, 8Ω part with a built-in heatsinking case which doubles as a mounting bracket. The 15 guage coil used in the 0.5mH position is actually a Jantzen air-core 0.47mH part. No other substitutions are required for any values, in any options or lines. All coils are Jantzen air-cores, whether 18 guage (standard) or 15 guage (upgrade), but the large 5mH coil used on the cornerhorns is an Erse Super-Q. All capacitors are poly caps.
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