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Low Earth Orbit
DIY Audio
New DIY Mid High (90deg) - AKA PM90
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<blockquote data-quote="Peter Morris" data-source="post: 132552" data-attributes="member: 652"><p>Re: New DIY Mid High</p><p></p><p></p><p></p><p></p><p><span style="font-size: 12px"><span style="color: #000000"><span style="font-family: 'Calibri'">Hi Uwe,</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'">The horn is a standard HF950. RCF's picture doesn’t really show the guide veins (fins) in the throat. The HF 950 with a BMS 4594 measures very much like RCF’s spec sheet in terms of directivity.</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'">I actually did some very rough modelling before I built the proto type. It turned out as expected; the two MF horns exits act as a dipole keeping the vertical pattern around 50 degrees at the crossover point, slowly becoming wider as the frequency decreases. There is good control down to about 300Hz. The issue is the HF horn only maintains its pattern control down to about 1.5Hkz to 2.0KHz at which point it becomes a bit wide, as you would expect having a height of 300mm.</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'">There is no other HF horn that I could find that did any better and still be able to fit into a reasonable size box ... many actually exhibited the classic pattern flip below about 1.5 KHz.</span></span></span></p><p><span style="font-size: 12px"><span style="color: #000000"><span style="font-family: 'Calibri'"></span></span></span>e.g. <a href="http://www.eighteensound.it/PRODUCTS/Products/CatID/5/ProdID=180#.VH7dfWkbrq4" target="_blank">http://www.eighteensound.it/PRODUCTS/Products/CatID/5/ProdID=180#.VH7dfWkbrq4</a></p><p></p><p><span style="font-size: 12px"><span style="color: #000000"><span style="font-family: 'Calibri'">RCF use the HF950 in their new TT5a which is crossed at 650Hz. I would expect the HF directivity to be very much the same. The width of the box will probably mean it has similar horizontal dispersion to the TT but vertically it will be somewhat narrower below 600 Hz. I have drawn what I expected in red on the TT5a directivity plots. </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'"></span></span></span><span style="font-size: 12px"><span style="color: #000000"><span style="font-family: 'Calibri'">My very rough measurements so far seem to confirm this.</span></span></span></p></blockquote><p></p>
[QUOTE="Peter Morris, post: 132552, member: 652"] Re: New DIY Mid High [SIZE=3][COLOR=#000000][FONT=Calibri]Hi Uwe, The horn is a standard HF950. RCF's picture doesn’t really show the guide veins (fins) in the throat. The HF 950 with a BMS 4594 measures very much like RCF’s spec sheet in terms of directivity. [/FONT][/COLOR][/SIZE] [SIZE=3][COLOR=#000000][FONT=Calibri]I actually did some very rough modelling before I built the proto type. It turned out as expected; the two MF horns exits act as a dipole keeping the vertical pattern around 50 degrees at the crossover point, slowly becoming wider as the frequency decreases. There is good control down to about 300Hz. The issue is the HF horn only maintains its pattern control down to about 1.5Hkz to 2.0KHz at which point it becomes a bit wide, as you would expect having a height of 300mm. There is no other HF horn that I could find that did any better and still be able to fit into a reasonable size box ... many actually exhibited the classic pattern flip below about 1.5 KHz. [/FONT][/COLOR][/SIZE]e.g. [URL]http://www.eighteensound.it/PRODUCTS/Products/CatID/5/ProdID=180#.VH7dfWkbrq4[/URL] [SIZE=3][COLOR=#000000][FONT=Calibri]RCF use the HF950 in their new TT5a which is crossed at 650Hz. I would expect the HF directivity to be very much the same. The width of the box will probably mean it has similar horizontal dispersion to the TT but vertically it will be somewhat narrower below 600 Hz. I have drawn what I expected in red on the TT5a directivity plots. [/FONT][/COLOR][/SIZE][SIZE=3][COLOR=#000000][FONT=Calibri]My very rough measurements so far seem to confirm this.[/FONT][/COLOR][/SIZE] [/QUOTE]
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