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New DIY Mid High (90deg) - AKA PM90
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<blockquote data-quote="Peter Morris" data-source="post: 133041" 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">Here are some more details:-</span></span></span></p><p> <span style="font-family: 'Calibri'"><span style="font-size: 12px"><span style="color: #000000"></span></span></span></p><p><u><span style="font-family: 'Calibri'"><span style="font-size: 12px"><span style="color: #000000">HF Driver and Horn</span></span></span></u></p><p><span style="font-family: 'Calibri'"><span style="font-size: 12px"><span style="color: #000000">The one thing that makes this box work is the BMS 4594. It allows the crossover to the low mid to be around 600 – 700Hz. The new HE version has a slightly flatter frequency response and uses shorting rings for lower distortion. </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 BMS 4594 is coupled to one of RCF’s new HF950 horns. I suspect this is one of the best horn flares RCF have made. It’s used in their newTT2a and TT5a and has a cut of frequency of 400Hz.</span></span></span></p><p><u><span style="font-family: 'Calibri'"><span style="font-size: 12px"><span style="color: #000000"></span></span></span></u></p><p><u><span style="font-family: 'Calibri'"><span style="font-size: 12px"><span style="color: #000000">Pattern Control </span></span></span></u></p><p><span style="font-family: 'Calibri'"><span style="font-size: 12px"><span style="color: #000000">The size of the HF horn and the wavelengths involved allowed it to be mounted in the centre of the mid horn. By doing that, the MIDs are in a dipole configuration which controls the vertical pattern to around 40 – 50 degrees, maintaining good pattern control down to 200Hz. It performed exactly as predicted by the simulations I ran during the conceptual design stages. The only compromise is that the HF horn gets a bit wide between 800 – 1500Hz, although in practice it does not appear to be an issue.</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">Consider looking at some plots of your typical 15 and view the off axis vertical frequency response - this information is hard to find, but here are some examples below; in comparison this DIY box is excellent; the only boxes I know that will do marginally better are perhaps some of Danley’s large Synergy horns, but the compromise for achieving better pattern control is that the box needs to be significantly larger.</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 or below the crossover frequency the width of the mid horn is such that its shape has less impact than its overall width on controlling horizontal directivity. Because both the MID and HF horns have the same width, the directivity transition between the two is very well matched. The horizontal pattern and off axis frequency response are as good as I have seen.</span></span></span></p><p> <span style="font-family: 'Calibri'"><span style="font-size: 12px"><span style="color: #000000"></span></span></span></p><p><u><span style="font-family: 'Calibri'"><span style="font-size: 12px"><span style="color: #000000">Mid Horn</span></span></span></u></p><p><span style="font-family: 'Calibri'"><span style="font-size: 12px"><span style="color: #000000">The mid horn is an exponential horn with a compression ratio of about 3 to 1 and a length of about 600mm. As noted above, it’s ported at about 85Hz with ports venting into the mouth of the horn.</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">It uses 2 x RCF 12 inch neo’s, and once again I selected a very new and low distortion driver. </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">There are some slightly more powerful drivers that will produce a little more SPL; however they have larger magnets and are heaver. These drivers would have made the box close to 40Kgs which was more than I wanted ….. my prototypes are 34Kgs including paint and speaker grill. </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 modelled every suitable driver I could find during my research in Hornresp. To get the box to go down to 100Hz and still maintain a reasonable size enclosure required the horn to be ported at around 85Hz. I would have preferred to use a pure horn and not to port the box, but without it, the box became too big.</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 port also minimizes the cone excursion, which was matched to the selected driver and its power rating, thus maximizing the efficiency. Cone excursion should not be a problem above70 Hz. </span></span></span></p><p><span style="font-family: 'Calibri'"><span style="font-size: 12px"><span style="color: #000000">The trick with this design is that the 12 inch is operating only in its piston range typically below approximately 700Hz. The volume between the cone and horn mouth acts as a low pass filter. Many designs using that use 12 inch mids required the mid to operate up to 1200 Hz or more, however, when using the lightest cone available it is generally not possible to get a 12 inch driver to go above 700Hz and operate as a piston. By operating the MID only in its piston range ensures low distortion and excellent sound quality.</span></span></span></p><p><u><span style="font-family: 'Calibri'"><span style="font-size: 12px"><span style="color: #000000"></span></span></span></u></p><p><u><span style="font-family: 'Calibri'"><span style="font-size: 12px"><span style="color: #000000">Box Construction</span></span></span></u></p><p><span style="font-family: 'Calibri'"><span style="font-size: 12px"><span style="color: #000000">The box is constructed with lightweight 17mm ply, but it has significant bracing and many of the internal surfaces are curved resulting in a lightweight ridge enclosure. There is also virtually no dead space within the box, as every part of the box forms either the horn flare or the speaker enclosure. This minimizes its size and weight. Even the pole mount is integrated into the enclosure to provide extra bracing between the base and centre speaker enclosure.</span></span></span></p><p><span style="font-family: 'Calibri'"><span style="font-size: 12px"><span style="color: #000000"></span></span></span></p><p><u><span style="font-family: 'Calibri'"><span style="font-size: 12px"><span style="color: #000000">Listening Tests</span></span></span></u></p><p><span style="font-family: 'Calibri'"><span style="font-size: 12px"><span style="color: #000000">Without a doubt this speaker exceeds the sonic performances of any speaker I have ever owned. It sounds better and measures better; its impulse response is as good as I have ever seen and there are very few speakers in the world that can reproduce a square wave both on and off axis (horizontal and vertical).</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="color: #000000"><span style="font-family: 'Symbol'"><span style="font-size: 12px">·</span> </span><span style="font-family: 'Calibri'"><span style="font-size: 12px">EAW – KF730-UX8800, KF650z-UX8800, KF750-UX8800,DSA 250</span></span></span></p><p><span style="color: #000000"><span style="font-family: 'Symbol'"><span style="font-size: 12px">·</span> </span><span style="font-family: 'Calibri'"><span style="font-size: 12px">Nexo PS15</span></span></span></p><p><span style="color: #000000"><span style="font-family: 'Symbol'"><span style="font-size: 12px">·</span> </span><span style="font-family: 'Calibri'"><span style="font-size: 12px">RCF TT22a, TT2a</span></span></span></p><p><span style="color: #000000"><span style="font-family: 'Symbol'"><span style="font-size: 12px">·</span> </span><span style="font-family: 'Calibri'"><span style="font-size: 12px">Turbosound Flex, TMW115, TMW112</span></span></span></p><p><span style="color: #000000"><span style="font-family: 'Symbol'"><span style="font-size: 12px">·</span> </span><span style="font-family: 'Calibri'"><span style="font-size: 12px">Meyer UPA </span></span></span></p><p></p><p><u><span style="font-family: 'Calibri'"><span style="color: #000000"><span style="font-size: 12px">Reference Material</span></span></span></u></p><p><a href="http://www.rcf.it/en_US/products/precision-transducers/neodymium-low-frequency-transducers/mb12n351" target="_blank"><span style="font-family: 'Calibri'"><span style="font-size: 12px"><span style="color: #0000ff">http://www.rcf.it/en_US/products/precision-transducers/neodymium-low-frequency-transducers/mb12n351</span></span></span></a><span style="font-family: 'Calibri'"><span style="color: #000000"><span style="font-size: 12px">- RCF 12 inch</span></span></span></p><p><a href="http://www.rcf.it/en_US/products/precision-transducers/horns/hf950" target="_blank"><span style="font-family: 'Calibri'"><span style="font-size: 12px"><span style="color: #0000ff">http://www.rcf.it/en_US/products/precision-transducers/horns/hf950</span></span></span></a><span style="font-family: 'Calibri'"><span style="color: #000000"><span style="font-size: 12px">- RCF Horn</span></span></span></p><p><a href="http://www.jblpro.com/ProductAttachments/VP7315_64%5b1%5d.pdf" target="_blank"><span style="font-family: 'Calibri'"><span style="font-size: 12px"><span style="color: #0000ff">http://www.jblpro.com/ProductAttachments/VP7315_64[1].pdf</span></span></span></a><span style="font-family: 'Calibri'"><span style="color: #000000"><span style="font-size: 12px"> - see off axis frequency response</span></span></span></p><p><a href="http://www.electrovoice.com/product.php?id=29" target="_blank"><span style="font-family: 'Calibri'"><span style="font-size: 12px"><span style="color: #0000ff">http://www.electrovoice.com/product.php?id=29</span></span></span></a><span style="font-family: 'Calibri'"><span style="color: #000000"><span style="font-size: 12px"> down load Pdf – see off axis frequencyresponse</span></span></span></p><p><a href="http://www.renkus-heinz.com/upload/st-stx4-datasheet-1.pdf" target="_blank"><span style="font-family: 'Calibri'"><span style="font-size: 12px"><span style="color: #0000ff">http://www.renkus-heinz.com/upload/st-stx4-datasheet-1.pdf</span></span></span></a><span style="font-size: 12px"><span style="color: #000000"><span style="font-family: 'Calibri'">- similar concept </span></span></span></p></blockquote><p></p>
[QUOTE="Peter Morris, post: 133041, member: 652"] Re: New DIY Mid High [FONT=Calibri][SIZE=3][COLOR=#000000]Here are some more details:- [/COLOR][/SIZE][/FONT] [U][FONT=Calibri][SIZE=3][COLOR=#000000]HF Driver and Horn[/COLOR][/SIZE][/FONT][/U] [FONT=Calibri][SIZE=3][COLOR=#000000]The one thing that makes this box work is the BMS 4594. It allows the crossover to the low mid to be around 600 – 700Hz. The new HE version has a slightly flatter frequency response and uses shorting rings for lower distortion. [/COLOR][/SIZE][/FONT] [FONT=Calibri][SIZE=3][COLOR=#000000]The BMS 4594 is coupled to one of RCF’s new HF950 horns. I suspect this is one of the best horn flares RCF have made. It’s used in their newTT2a and TT5a and has a cut of frequency of 400Hz.[/COLOR][/SIZE][/FONT] [U][FONT=Calibri][SIZE=3][COLOR=#000000] Pattern Control [/COLOR][/SIZE][/FONT][/U] [FONT=Calibri][SIZE=3][COLOR=#000000]The size of the HF horn and the wavelengths involved allowed it to be mounted in the centre of the mid horn. By doing that, the MIDs are in a dipole configuration which controls the vertical pattern to around 40 – 50 degrees, maintaining good pattern control down to 200Hz. It performed exactly as predicted by the simulations I ran during the conceptual design stages. The only compromise is that the HF horn gets a bit wide between 800 – 1500Hz, although in practice it does not appear to be an issue. [/COLOR][/SIZE][/FONT] [FONT=Calibri][SIZE=3][COLOR=#000000]Consider looking at some plots of your typical 15 and view the off axis vertical frequency response - this information is hard to find, but here are some examples below; in comparison this DIY box is excellent; the only boxes I know that will do marginally better are perhaps some of Danley’s large Synergy horns, but the compromise for achieving better pattern control is that the box needs to be significantly larger. [/COLOR][/SIZE][/FONT] [FONT=Calibri][SIZE=3][COLOR=#000000] At or below the crossover frequency the width of the mid horn is such that its shape has less impact than its overall width on controlling horizontal directivity. Because both the MID and HF horns have the same width, the directivity transition between the two is very well matched. The horizontal pattern and off axis frequency response are as good as I have seen. [/COLOR][/SIZE][/FONT] [U][FONT=Calibri][SIZE=3][COLOR=#000000]Mid Horn[/COLOR][/SIZE][/FONT][/U] [FONT=Calibri][SIZE=3][COLOR=#000000]The mid horn is an exponential horn with a compression ratio of about 3 to 1 and a length of about 600mm. As noted above, it’s ported at about 85Hz with ports venting into the mouth of the horn. [/COLOR][/SIZE][/FONT] [FONT=Calibri][SIZE=3][COLOR=#000000]It uses 2 x RCF 12 inch neo’s, and once again I selected a very new and low distortion driver. [/COLOR][/SIZE][/FONT] [FONT=Calibri][SIZE=3][COLOR=#000000] There are some slightly more powerful drivers that will produce a little more SPL; however they have larger magnets and are heaver. These drivers would have made the box close to 40Kgs which was more than I wanted ….. my prototypes are 34Kgs including paint and speaker grill. [/COLOR][/SIZE][/FONT] [FONT=Calibri][SIZE=3][COLOR=#000000]I modelled every suitable driver I could find during my research in Hornresp. To get the box to go down to 100Hz and still maintain a reasonable size enclosure required the horn to be ported at around 85Hz. I would have preferred to use a pure horn and not to port the box, but without it, the box became too big. [/COLOR][/SIZE][/FONT] [FONT=Calibri][SIZE=3][COLOR=#000000]The port also minimizes the cone excursion, which was matched to the selected driver and its power rating, thus maximizing the efficiency. Cone excursion should not be a problem above70 Hz. [/COLOR][/SIZE][/FONT] [FONT=Calibri][SIZE=3][COLOR=#000000]The trick with this design is that the 12 inch is operating only in its piston range typically below approximately 700Hz. The volume between the cone and horn mouth acts as a low pass filter. Many designs using that use 12 inch mids required the mid to operate up to 1200 Hz or more, however, when using the lightest cone available it is generally not possible to get a 12 inch driver to go above 700Hz and operate as a piston. By operating the MID only in its piston range ensures low distortion and excellent sound quality.[/COLOR][/SIZE][/FONT] [U][FONT=Calibri][SIZE=3][COLOR=#000000] Box Construction[/COLOR][/SIZE][/FONT][/U] [FONT=Calibri][SIZE=3][COLOR=#000000]The box is constructed with lightweight 17mm ply, but it has significant bracing and many of the internal surfaces are curved resulting in a lightweight ridge enclosure. There is also virtually no dead space within the box, as every part of the box forms either the horn flare or the speaker enclosure. This minimizes its size and weight. Even the pole mount is integrated into the enclosure to provide extra bracing between the base and centre speaker enclosure. [/COLOR][/SIZE][/FONT] [U][FONT=Calibri][SIZE=3][COLOR=#000000]Listening Tests[/COLOR][/SIZE][/FONT][/U] [FONT=Calibri][SIZE=3][COLOR=#000000]Without a doubt this speaker exceeds the sonic performances of any speaker I have ever owned. It sounds better and measures better; its impulse response is as good as I have ever seen and there are very few speakers in the world that can reproduce a square wave both on and off axis (horizontal and vertical). [/COLOR][/SIZE][/FONT] [COLOR=#000000][FONT=Symbol][SIZE=3]·[/SIZE] [/FONT][FONT=Calibri][SIZE=3]EAW – KF730-UX8800, KF650z-UX8800, KF750-UX8800,DSA 250[/SIZE][/FONT][/COLOR] [COLOR=#000000][FONT=Symbol][SIZE=3]·[/SIZE] [/FONT][FONT=Calibri][SIZE=3]Nexo PS15[/SIZE][/FONT][/COLOR] [COLOR=#000000][FONT=Symbol][SIZE=3]·[/SIZE] [/FONT][FONT=Calibri][SIZE=3]RCF TT22a, TT2a[/SIZE][/FONT][/COLOR] [COLOR=#000000][FONT=Symbol][SIZE=3]·[/SIZE] [/FONT][FONT=Calibri][SIZE=3]Turbosound Flex, TMW115, TMW112[/SIZE][/FONT][/COLOR] [COLOR=#000000][FONT=Symbol][SIZE=3]·[/SIZE] [/FONT][FONT=Calibri][SIZE=3]Meyer UPA [/SIZE][/FONT][/COLOR] [U][FONT=Calibri][COLOR=#000000][SIZE=3]Reference Material[/SIZE][/COLOR][/FONT][/U] [URL="http://www.rcf.it/en_US/products/precision-transducers/neodymium-low-frequency-transducers/mb12n351"][FONT=Calibri][SIZE=3][COLOR=#0000ff]http://www.rcf.it/en_US/products/precision-transducers/neodymium-low-frequency-transducers/mb12n351[/COLOR][/SIZE][/FONT][/URL][FONT=Calibri][COLOR=#000000][SIZE=3]- RCF 12 inch[/SIZE][/COLOR][/FONT] [URL="http://www.rcf.it/en_US/products/precision-transducers/horns/hf950"][FONT=Calibri][SIZE=3][COLOR=#0000ff]http://www.rcf.it/en_US/products/precision-transducers/horns/hf950[/COLOR][/SIZE][/FONT][/URL][FONT=Calibri][COLOR=#000000][SIZE=3]- RCF Horn[/SIZE][/COLOR][/FONT] [URL="http://www.jblpro.com/ProductAttachments/VP7315_64%5b1%5d.pdf"][FONT=Calibri][SIZE=3][COLOR=#0000ff]http://www.jblpro.com/ProductAttachments/VP7315_64[1].pdf[/COLOR][/SIZE][/FONT][/URL][FONT=Calibri][COLOR=#000000][SIZE=3] - see off axis frequency response[/SIZE][/COLOR][/FONT] [URL="http://www.electrovoice.com/product.php?id=29"][FONT=Calibri][SIZE=3][COLOR=#0000ff]http://www.electrovoice.com/product.php?id=29[/COLOR][/SIZE][/FONT][/URL][FONT=Calibri][COLOR=#000000][SIZE=3] down load Pdf – see off axis frequencyresponse[/SIZE][/COLOR][/FONT] [URL="http://www.renkus-heinz.com/upload/st-stx4-datasheet-1.pdf"][FONT=Calibri][SIZE=3][COLOR=#0000ff]http://www.renkus-heinz.com/upload/st-stx4-datasheet-1.pdf[/COLOR][/SIZE][/FONT][/URL][SIZE=3][COLOR=#000000][FONT=Calibri]- similar concept [/FONT][/COLOR][/SIZE] [/QUOTE]
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