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Multi-Way Conventional loudspeakers with crossovers

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Old 14th February 2004, 08:29 AM   #111
rabbitz is offline rabbitz  Australia
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Give me a couple of days and I'll email you a series xo.
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Old 17th March 2004, 01:29 AM   #112
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Something that's been bugging me:

The Esquire and rabbitz's design have similar volumes. The Esquire uses a 1.625"L port while rabbitz's is about 3.75"L (both have similar port diamaters). My results using WinISD are closer to rabbitz's.

What's the deal?
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Old 17th March 2004, 02:37 AM   #113
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Default Re: Re: rabitz comment

Quote:
Originally posted by rabbitz


There might be a way of measuring individual drivers in a series crossover..... don't know....... maybe simple as disconnecting the other driver and replacing it with a resistor...... does anyone know?

Replacing the other driver with a resistor won't work.

Take the driver you don't want to measure, attach a long cord (low DCR) and put it in the closet in another room. Or put it outdoors.
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Old 17th March 2004, 01:56 PM   #114
rabbitz is offline rabbitz  Australia
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Quote:
Originally posted by coolkhoa
Something that's been bugging me:

The Esquire and rabbitz's design have similar volumes. The Esquire uses a 1.625"L port while rabbitz's is about 3.75"L (both have similar port diamaters). My results using WinISD are closer to rabbitz's.

What's the deal?
I'll see if I can get rid of that bug.

Firstly, even though the port diameters look close, they are not and there is quite a difference in length when using different diameters. In WinISD, try again with a 39mm dia and then try with a 32mm dia...... the length will be about half. Also the Fb I used was a little lower.

Secondly, the Esquire uses a different BR alignment. Mine and WinISD used a QB3 where the Esquire uses a SC4 which is quite different. He also did some fine tuning on the port after building which looks like reduced the length further.

Hope this clears it up for you.

You can always do it the long way by calculator:

L = ((1.463 x (10^7 x R^2))/(Fb^2 x Vb)) - 1.463R

L=length in inches, R=radius of port in inches, Fb=tuning freq Hz, Vb=box volume in cubic inches

Software's easier hey!
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Old 17th March 2004, 07:57 PM   #115
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Quote:
Originally posted by rabbitz

Firstly, even though the port diameters look close, they are not and there is quite a difference in length when using different diameters. In WinISD, try again with a 39mm dia and then try with a 32mm dia...... the length will be about half.

WinISD only has preset diameters for the port...couldn't verify (I should try it manually). Yes, the Esquire and your design use different alignments, but consider this: According to the designer of the Esquire, Vifa's literature suggests a QB3 alignment a bit different from yours.

Should we consider this design?
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Old 17th March 2004, 08:12 PM   #116
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Is this idea still alive? I just finished reading the entire topic and have gotten very interested. Just whish I had seen this sooner (I've been away from diyaudio.com for a long time).
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Old 17th March 2004, 09:16 PM   #117
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Yes, the idea is still alive.

I wonder if the smallest of the Woodstyle enclosures (5.3 L) from Madisound would be a good starting point for newbies to build the P13/D27 combo. It's a tad small if you take into account the volume taken by the drivers and port, though.
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Old 17th March 2004, 09:37 PM   #118
weeghel is offline weeghel  Netherlands
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Where can I read more about this?
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Old 18th March 2004, 11:05 AM   #119
rabbitz is offline rabbitz  Australia
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Quote:
Originally posted by coolkhoa



WinISD only has preset diameters for the port...couldn't verify (I should try it manually). Yes, the Esquire and your design use different alignments, but consider this: According to the designer of the Esquire, Vifa's literature suggests a QB3 alignment a bit different from yours.

Should we consider this design?
I don't know where the Vifa data comes from. That only uses a 25.4mm port with a length of 38mm and a volume of 5 litres. All of these are variables, so if you change 1 or more the result is going to be different. There's more than one way to skin a cat (sorry cat lovers).

I've used a Vb=5.3 litre with 5.5 actual box volume and the 39mm port size is to get the port noise down.

In WinISD try typing a different port diameter in manually and see what happens to the length...... changes - gets shorter for a smaller dia and longer for a larger dia. Then have a look at the Vent Mach... if the port's too small it will go into the red. I try and keep it below 18.

weeghel, if you want more info have a look at the Wiki and you'll see it in the list.
http://www.diyaudio.com/wiki/index.php?page=Projects
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Old 18th March 2004, 11:16 AM   #120
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thanks
I checked the wiki out yesterday, but hadn't seen this page. I guess it's the vifa newbie project? Not much info on there yet.

I've been looking for an excuse to start a new speaker project, maybe this is one
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