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Double 10" Sealed Enclosure Advice please |
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JonB67 
Young Croc 
Joined: 22 April 2016 Location: UK Status: Offline Points: 1376 |
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 Posted: 07 May 2020 at 7:01pm |
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Post up a build thread. We all love a build thread. Lots of pics please
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Jack1991
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Joined: 05 February 2020 Location: Bristol Status: Offline Points: 495 |
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Posted: 07 May 2020 at 4:14pm |
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Update: all glued now. Time for a few ciders!
 Then tommorow sand fill and router! Also should i be posting the build in here? I kind of went a bit off topic and now its its turning into the build page for the whole project. Edited by Jack1991 - 07 May 2020 at 4:14pm |
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Jack1991
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Joined: 05 February 2020 Location: Bristol Status: Offline Points: 495 |
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Posted: 07 May 2020 at 11:59am |
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Yes it is going to be a 12v sound system. I have a Pioneer 8704 4 channel class d amplifier for it. I may get a dsp in the future but im still learning and dont really understand the dsp settings etc just yet. So going to try and learn as i go with it. Will check that link out now too mate cheers
Edited by Jack1991 - 07 May 2020 at 12:00pm |
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Earplug
Old Croc 
Joined: 03 January 2012 Location: Europe Status: Offline Points: 7216 |
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Posted: 07 May 2020 at 10:42am |
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+1 What I was worried about as well. Just don´t stick any ferrite material in an air core inductor. |
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Earplugs Are For Wimps!
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APW
Young Croc
Joined: 13 November 2012 Location: Kent, UK Status: Offline Points: 1174 |
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Posted: 07 May 2020 at 10:02am |
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The main issue isn’t the change in inductance, its core saturation…. Basically in the "real world" air cored inductor don’t saturate (…. they do but at very very high power levels), as soon as you introduce a peace of ferric material into the inductor core space you no-longer have an air cored inductor and at some point you will hit the saturation knee, at this point your inductor is now non-linear and distortion accrues. The smaller the amount of magnetic material in the core the lower the power it which it will saturate so a small screw will saturate at low power were as a large pump of iron will saturate at higher power levels. …. And then we have Eddy currents in the core to consider! |
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Earplug
Old Croc
Joined: 03 January 2012 Location: Europe Status: Offline Points: 7216 |
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Posted: 07 May 2020 at 9:21am |
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Haha, ok - it obviously depends on the size of screw/bolt you use. And 0,401 -> 0,411 is a 3% increase. 0,401 -> 0,550 is a 37% increase! Or are you using some other idea of %?  I would also be worried about saturation effects that any bolt in there might cause at high currents. |
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Earplugs Are For Wimps!
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Jo bg
Young Croc
Joined: 08 March 2017 Status: Offline Points: 552 |
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Posted: 07 May 2020 at 5:20am |
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By the way your stack looks perfect for a mobile system. Have a look at this wonderful 12V amp with dsp by a member here
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Jo bg
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Joined: 08 March 2017 Status: Offline Points: 552 |
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Posted: 07 May 2020 at 5:13am |
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This would make dispersion not exactly symmetrical, If your massive likes to stay on one side of the sound... Note that sound does not stop suddendly at 90 degree its just the point where should be around 6db down over most of his passband, it slowly rolls off from on axis. Difference should not be night and day, and you can try it quickly just unscrewing the horn, so try and see if it.suits you.
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Jack1991
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Joined: 05 February 2020 Location: Bristol Status: Offline Points: 495 |
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Posted: 06 May 2020 at 9:06pm |
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Oh ok cool thats a good idea, makes sense. I will fit it with the lines going vertical instead of horizontal then, thanks.
Would it be worth having 1 going horizontal and one going vertical?? Edited by Jack1991 - 06 May 2020 at 9:10pm |
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Jo bg
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Joined: 08 March 2017 Status: Offline Points: 552 |
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Posted: 06 May 2020 at 8:59pm |
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Yes, you can see the walls are wider on the horizontal plane , there should be 90 degree dispersion on that plane.
Difference should be apparent off axis, not in front. As the stack is not tall you could try also putting the 90 in the verticl plane to give more highs to people nearby. This could reduce comb filter, as you reduce the common area of the two horns, but you get more reflections from ground and ceiling if inside. Compromises as always.
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Jack1991
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Joined: 05 February 2020 Location: Bristol Status: Offline Points: 495 |
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Posted: 06 May 2020 at 8:41pm |
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The horns for the tops i have noticed have 2 lines on. Do i want to have these lines going horrizontal or vertical? Im assuming its to show the 90 or 60°dispersion maybe?
Either way i can barely see a difference at all but im sure there ment to go a certain way??  Edited by Jack1991 - 06 May 2020 at 9:08pm |
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Peter Jan
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Joined: 16 December 2008 Location: Belgium Status: Offline Points: 1019 |
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Posted: 06 May 2020 at 8:13pm |
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You know... over the last 2-3 decades people have said/asked me about this about fixing aircoil inductors on plastic formers with metal screws and I did measure things up a few times. To know for myself in the first place and to have figures in my head to be able to state solid figures and not just an interpretation/appxoximation of a theory. So (again) I grabbed a few parts out of the drawer and measured things up. Took a coil of 0,4 mH, measured in free air : 0,401 mH Fixed the coil to a piece of 18mm birch ply with a 16 mm long steel woodscrew : 0,408 mH Added an extra 1 mm thick steel washer : 0,411 mH So it's a bit more than one tenth of a percent, but certainly not anywhere near 20 % or so. While fixing the screw with a screwdriver, my meter displayed about 0,550 mH, but my advice would be to not let the screwdriver in, you know My memory seems a tiny bit out of whack (on that one tenth of a percent), but I think I'm still gonna stick by what I said earlier anyway. As always ... your mileage may vary  |
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Jo bg wrote: