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1850horn rear chamber size? |
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Sencesync 
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Joined: 17 April 2005 Location: United States Status: Offline Points: 180 |
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 Topic: 1850horn rear chamber size?Posted: 20 August 2005 at 8:26pm |
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anyone know how much volume the rear chamber is for the 1850horn?
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rastaman
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Joined: 20 May 2005 Location: United States Status: Offline Points: 421 |
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Posted: 20 August 2005 at 8:30pm |
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1 litre = 1,000,000 millimetres cubed
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Sencesync
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Posted: 20 August 2005 at 8:39pm |
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Rastaman, thats NOT what im looking for. im looking for the rear chamber volume size. not the convertion for millimeters to litres...
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Sencesync
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Posted: 20 August 2005 at 11:51pm |
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see this is why im trying to get the info from others. because i keep comming up with 69.74 litres no matter how many times i check it. and i HIGHLY doubt that thier is nearly 2.5cuf (70.8 litres) of rearchamber space in the 1850horn. so please tell me other-wise because i dont believe that there is that much room, it would seem like there should be less room.
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rastaman
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Posted: 21 August 2005 at 10:12am |
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Ballpark it, it looks not bad to me.
Take the 3 largest measurements of the rear chamber as if it were a cube, you get about 87l, take the 3 smallest you get about 56l. Somewhere Rog talks about designing short horns as a sealed box unit first, which for the 1850 recommended enclosures are 90-220. Course I could be making the exact same mistakes as you, but oh well. |
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Timber_MG
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Posted: 21 August 2005 at 3:53pm |
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Subtract the volume occupied by the driver. Other than that, high
scool geometry will get you to the answer fairly quickly.
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rastaman
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Posted: 21 August 2005 at 4:24pm |
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Yeah Rog says in the FAQ a standard 18" will occupy about 7litres if
memory serves. Seeing as he specs the 1850 for just about everything,
thats probably his standard
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Timber_MG
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Posted: 21 August 2005 at 5:02pm |
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I'd expect that spec from PD, though to be truly exact one would have
to look at a little more detail (like thickness of the wood its being
mounted in)
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tb_mike
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Joined: 01 October 2004 Location: New Zealand Status: Offline Points: 2744 |
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Posted: 28 August 2005 at 2:57am |
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if you were one who must split inaudible hairs that is |
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loophole
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Posted: 10 September 2005 at 9:01am |
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not that inaudible mike.
an 18" hole in a double-thickness baffle (ie 36mm) is over 5 litres. certainly not incondsiderable i measure the rear chamber to be about 68 litres too. that seems about right, but im almost certain the pd1850 must be more than 7 litres... i would say about 15-20 is more along the right lines. and even that seems small compared to how much space it visibly takes up in the chamber |
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minaximal
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Joined: 26 September 2004 Location: United Kingdom Status: Offline Points: 1780 |
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Posted: 16 September 2005 at 7:36am |
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i contacted mark from pd a while ago, and he said they work on a volume of approximately 6 litres of displacement from the 1850, i worked out the concave cone area to add up to around 3 litres to the throat area. looking back at my old spreadsheets: if the baffle hole for an 18" is 43cm dia, and 1.8cm deep, thats 2.6l on top of 3 litres, before counting the actual throat area. although dont forget the pistonic motion of a driver increases and decreases the area with each stoke... haha nothing is that simple |
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Timber_MG wrote:
, and these are things which can easily get forgotten.