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Low Earth Orbit
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New DIY Mid High (90deg) - AKA PM90
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<blockquote data-quote="Peter Morris" data-source="post: 138746" data-attributes="member: 652"><p>Re: New DIY Mid High</p><p></p><p></p><p></p><p><span style="font-family: 'Calibri'"><span style="font-size: 12px"><span style="color: #000000">As I have mentioned earlier this box was built as a prototype. While I’m quite competent with most woodwork and metal work projects I don’t have a serious workshop or any drawing software.</span></span></span></p><p><span style="font-family: 'Calibri'"><span style="font-size: 12px"><span style="color: #000000"></span></span></span></p><p><span style="font-family: 'Calibri'"><span style="font-size: 12px"><span style="color: #000000">What I did was sketch up a full scale drawing of halve the box and checked it fitted the horn response design criteria.</span></span></span></p><p> <span style="font-family: 'Calibri'"><span style="font-size: 12px"><span style="color: #000000"></span></span></span></p><p><span style="font-family: 'Calibri'"><span style="font-size: 12px"><span style="color: #000000">I then worked out a way to construct the box with the tools I had. For example, many of the angles I just hand planed until correct.</span></span></span></p><p><span style="font-family: 'Calibri'"><span style="font-size: 12px"><span style="color: #000000"> </span></span></span></p><p><span style="font-family: 'Calibri'"><span style="font-size: 12px"><span style="color: #000000">At this stage the best I can do is measure what I have done and post it. The shape of the curved mouth of the horn is not that critical. The frequency response if you model that section as conical or exponential is similar. By making curved (exponential) it increases the volume enclosing the two12’s to about the correct amount.</span></span></span></p><p><span style="font-family: 'Calibri'"><span style="font-size: 12px"><span style="color: #000000"> </span></span></span></p><p><span style="font-family: 'Calibri'"><span style="font-size: 12px"><span style="color: #000000">One critical dimension relates to the clearance between the horn driver and the spokes of the 12”. It all fits but there is not much room for error. Check that what you are going to do all fits. The location of the 4 ports is also not that critical – against the side of the box and a few inches from the front of the box. </span></span></span></p><p><span style="font-family: 'Calibri'"><span style="font-size: 12px"><span style="color: #000000"></span></span></span></p><p><span style="font-family: 'Calibri'"><span style="font-size: 12px"><span style="color: #000000">The next thing I was planning to was build some 60 degree versions …. Now that I have tested the concept and it works I will take some more time and do some better plans ...and now that March is almost over I should have some more time. </span></span></span></p><p><span style="font-family: 'Calibri'"><span style="font-size: 12px"><span style="color: #000000"></span></span></span></p><p><span style="font-size: 12px"><span style="color: #000000"><span style="font-family: 'Calibri'">In the meantime if anybody has some drawing software and sketches it up I could compare it to what I have made and suggest any changes that maybe necessary.</span></span></span></p><p><span style="font-size: 12px"><span style="color: #000000"><span style="font-family: 'Calibri'"></span></span></span></p><p><span style="font-size: 12px"><span style="color: #000000"><span style="font-family: 'Calibri'">Peter</span></span></span></p><p><span style="font-size: 12px"><span style="color: #000000"><span style="font-family: 'Calibri'"></span></span></span></p><p><span style="font-size: 12px"><span style="color: #000000"><span style="font-family: 'Calibri'">Box dimensions: <span style="font-family: 'Calibri'"><span style="font-size: 12px"><span style="color: #000000">930mm - H x 430mm - D x 385mm - W</span></span></span></span></span></span></p><p><span style="font-size: 12px"><span style="color: #000000"><span style="font-family: 'Calibri'"><span style="font-family: 'Calibri'"><span style="font-size: 12px"><span style="color: #000000">Construction: 17mm ply (light weight pine braced)</span></span></span></span></span></span></p><p><span style="font-size: 12px"><span style="color: #000000"><span style="font-family: 'Calibri'"></span></span></span></p></blockquote><p></p>
[QUOTE="Peter Morris, post: 138746, member: 652"] Re: New DIY Mid High [FONT=Calibri][SIZE=3][COLOR=#000000]As I have mentioned earlier this box was built as a prototype. While I’m quite competent with most woodwork and metal work projects I don’t have a serious workshop or any drawing software.[/COLOR][/SIZE][/FONT] [FONT=Calibri][SIZE=3][COLOR=#000000] What I did was sketch up a full scale drawing of halve the box and checked it fitted the horn response design criteria. [/COLOR][/SIZE][/FONT] [FONT=Calibri][SIZE=3][COLOR=#000000]I then worked out a way to construct the box with the tools I had. For example, many of the angles I just hand planed until correct. [/COLOR][/SIZE][/FONT] [FONT=Calibri][SIZE=3][COLOR=#000000]At this stage the best I can do is measure what I have done and post it. The shape of the curved mouth of the horn is not that critical. The frequency response if you model that section as conical or exponential is similar. By making curved (exponential) it increases the volume enclosing the two12’s to about the correct amount.[/COLOR][/SIZE][/FONT] [FONT=Calibri][SIZE=3][COLOR=#000000] One critical dimension relates to the clearance between the horn driver and the spokes of the 12”. It all fits but there is not much room for error. Check that what you are going to do all fits. The location of the 4 ports is also not that critical – against the side of the box and a few inches from the front of the box. [/COLOR][/SIZE][/FONT] [FONT=Calibri][SIZE=3][COLOR=#000000] The next thing I was planning to was build some 60 degree versions …. Now that I have tested the concept and it works I will take some more time and do some better plans ...and now that March is almost over I should have some more time. [/COLOR][/SIZE][/FONT] [SIZE=3][COLOR=#000000][FONT=Calibri]In the meantime if anybody has some drawing software and sketches it up I could compare it to what I have made and suggest any changes that maybe necessary. Peter Box dimensions: [FONT=Calibri][SIZE=3][COLOR=#000000]930mm - H x 430mm - D x 385mm - W Construction: 17mm ply (light weight pine braced)[/COLOR][/SIZE][/FONT] [/FONT][/COLOR][/SIZE] [/QUOTE]
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