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121 wedge New build

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dlyxover View Drop Down
Young Croc
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Post Options Post Options   Thanks (0) Thanks(0)   Quote dlyxover Quote  Post ReplyReply Direct Link To This Post Topic: 121 wedge New build
    Posted: 22 October 2008 at 5:47pm
Im using BMS 12" and1" for a compact wedge/top cab
 
frequency responce
 
vent air velocity
 
 
Not convinced by the tuning winISD and bass box pro give differnt port lengths with the same input data.
 
Im going to build a prototype in the next 2 weeks.
 
Any input welcome


Edited by dlyxover - 01 March 2019 at 4:31pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Deadbeat Quote  Post ReplyReply Direct Link To This Post Posted: 22 October 2008 at 6:19pm
They should give roughly the same answers, working I should think on the same lumped parameter model.

Besides, you should be manually tuning the ports as well. Wink

Could you post both your BB and winisd inputs? I use BB myself.
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dlyxover View Drop Down
Young Croc
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Post Options Post Options   Thanks (0) Thanks(0)   Quote dlyxover Quote  Post ReplyReply Direct Link To This Post Posted: 22 October 2008 at 7:01pm
 
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dlyxover View Drop Down
Young Croc
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Post Options Post Options   Thanks (0) Thanks(0)   Quote dlyxover Quote  Post ReplyReply Direct Link To This Post Posted: 22 October 2008 at 7:06pm

Im a bit vexed on which to try first for the port length.

Ive read that people find bass box pro more reliable
 
whats the best way to go about manually tuning?
 
cheers
 
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Old Croc
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Deadbeat Quote  Post ReplyReply Direct Link To This Post Posted: 22 October 2008 at 8:01pm
When I take a big interest in a project, I make my ports a little longer, then spend a while with some tools for cutting it down and using an impedance measurement jig to determine tuning.

The graphs are almost identical, or is it my quite bad eyesight? Maybe look at end correction?
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dlyxover View Drop Down
Young Croc
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Post Options Post Options   Thanks (0) Thanks(0)   Quote dlyxover Quote  Post ReplyReply Direct Link To This Post Posted: 22 October 2008 at 8:14pm
the graphs are almost identical.
 
Im going to start with the bass box pro length.
 
what do you mean by end correction?
 
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Deadbeat View Drop Down
Old Croc
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Deadbeat Quote  Post ReplyReply Direct Link To This Post Posted: 22 October 2008 at 8:24pm
Bassbox Pro and winisd both have a port end correction coefficient which they modify port length by internally - this is usually denoted as 'K' and is why Bassbox asks you whether it has one or two flush lengths. Due to the massive change in acoustical resistance from the inside of the port to the outside, the port appears longer than it is. Think of it as the air in the port still thinking it's in the port as it exits. The exact coefficient changes with position of the port as well - you may find corner ports to act a little longer than they should.

If you search on here, I've done some pretty long posts on this - my hands are a bit tired atm sorry.
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dlyxover View Drop Down
Young Croc
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Post Options Post Options   Thanks (0) Thanks(0)   Quote dlyxover Quote  Post ReplyReply Direct Link To This Post Posted: 22 October 2008 at 8:38pm
I did wonder how winISD dealt with that.
 
thats cool, ive been reading some of them already becouse im wanting to use corner ports.
 
Im gona put a plan us in a bit, a friend of mine has smart im going to try and get him to help me with it when it built for the final tweeks and crossover.
 
Thank you for your help Deadbeat its really appreachiated


Edited by dlyxover - 23 October 2008 at 1:07am
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Old Croc
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Deadbeat Quote  Post ReplyReply Direct Link To This Post Posted: 22 October 2008 at 8:55pm
You're welcome. Do be sure to post your build pics!
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Young Croc
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Post Options Post Options   Thanks (0) Thanks(0)   Quote dlyxover Quote  Post ReplyReply Direct Link To This Post Posted: 23 October 2008 at 2:30am



Edited by dlyxover - 10 September 2011 at 12:57am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ceharden Quote  Post ReplyReply Direct Link To This Post Posted: 23 October 2008 at 2:40am
Use WinISD Alpha, the later version.  You can select the amount of end correction it uses for the port position.  It also has more graphs available etc.

For corner mounted ports you will get quite a lot of effective length increase so start a bit shorter than the simulations, you can always glue an extra bit on the back if the tuning is too high.  In WinISD select both ends flanged or flush mounted as this will be closer to reality.


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dlyxover View Drop Down
Young Croc
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Post Options Post Options   Thanks (0) Thanks(0)   Quote dlyxover Quote  Post ReplyReply Direct Link To This Post Posted: 23 October 2008 at 2:49am
I did try iy but the drive is not in the data base.
When I manually add the data it tells me its all wrony.
 
I try downloading it again.
 
If the port get much longer I'll have to have a re-think 
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