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Daft scoop question.... |
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jbl_man 
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Joined: 12 January 2005 Location: London. Status: Offline Points: 11308 |
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 Topic: Daft scoop question....Posted: 29 April 2007 at 9:17am |
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Ok,really silly question this..but....what does it sound like when u mount the driver the wrong-way-round?...the cone facing into the horn scoop,the magnet sticking out the front...totally inpractical i know,but might work for an install? anyone tried it?
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TONY.A.S.S.
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Joined: 21 February 2007 Location: United Kingdom Status: Offline Points: 6867 |
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Posted: 29 April 2007 at 10:26am |
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I've always assumed that the sound emitted from the rear is the same as the front, only 180 degrees out of phase. Speakers such as EV S118 had this arrangement because the speaker would not fit in the conventional way. I think thats about as technical as it gets.
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jbl_man
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Posted: 29 April 2007 at 11:12am |
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I thought the sound from the front of the cone all seemed to couple the air better,and was less obstructed by the frame/spider/magnet...just out of interest,maybe someone can try fitting a scoop with the driver upside down and report?
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Rog
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Rogers Archive Posts Joined: 23 March 2010 Status: Offline Points: 2166 |
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Posted: 29 April 2007 at 11:35am |
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Well, the effect of the front chamber now being bigger will effect the performance more than if the sound goes though the frame. By reversing the driver you now have a bigger front chamber, which will lower the low cutoff point, but not by much, will lower the upper cutoff point and reduce sensitvity. So a bit lower and not so loud. Most 18" drivers displace around 9 to 12 litres, so when you reverse the driver you add that and the 2 to 3 litres from the space in front of the cone. On large front chamber scoops the 14 litres will not make much difference, but on small chambered scoops 14 litres is quite a lot. I've done tests and meaurments of drivers used in all types of boxes and can find no difference in sound by reversing the driver. That is if the new chamber size is taken into account and the drivers polarity is reversed.
An interesting design can be had from reversing the driver in a scoop then building a box around it that is ported. But I'm not going to tell you what happens. You need to experiment yourself on this one Ian. Note I didn't say you need to experiment on yourself Ian. Well, you could do.
Edited by Rog Mogale - 29 April 2007 at 11:38am |
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jbl_man
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Posted: 29 April 2007 at 12:20pm |
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i just spotted this Rog....
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norty303
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Joined: 18 August 2004 Location: Eastbourne Status: Offline Points: 8800 |
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Posted: 29 April 2007 at 12:36pm |
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Isn't that a 6th order bandpass with a loooong flared port on the front chamber then?
21 eh? Achieved so much and yet so young......  Edited by norty303 - 29 April 2007 at 12:37pm |
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My laser stuff: Frikkin Lasers
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levyte357
The 10,000 Points Club 
Joined: 10 May 2004 Location: UK, London Status: Offline Points: 11743 |
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Posted: 01 May 2007 at 1:52am |
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Is that 21 in base 50? |
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"Who am I? I'm the guy who does his job.. You must be the other guy".
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Rog
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Rogers Archive Posts Joined: 23 March 2010 Status: Offline Points: 2166 |
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Posted: 01 May 2007 at 3:27am |
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No, just more like 50  Thank you for the birthday wishes guys, nice to know there's a few people left that don't hate me.
"Isn't that a 6th order bandpass with a loooong flared port on the front chamber then?"
Well as a long flared port has gain, isn't that a horn.......
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Rog
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Rogers Archive Posts Joined: 23 March 2010 Status: Offline Points: 2166 |
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Posted: 01 May 2007 at 3:30am |
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Lev,
I talked to Alex.
All the V18-1200's have been sold to guys in yard, so I got Alex to make a small run of them to give to people for demo's.
Should be ready in about 2 weeks. Sorry there were none about when I thought there were.
Rog.
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COWFOOT
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Posted: 02 May 2007 at 3:38am |
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Great move Rog in debuting the V18-1200 with Stone Love.Nuff free publicity.
I heard that Stone Love just got a bunch of amps that had the brand name removed.Where they came from I do not know.
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levyte357
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Posted: 04 May 2007 at 6:02pm |
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OK. Cheers. |
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"Who am I? I'm the guy who does his job.. You must be the other guy".
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An interesting design can be had from reversing the driver in a scoop then building a box around it that is ported.