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Low Earth Orbit
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60 Degree DIY Mid Hi - AKA PM60
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<blockquote data-quote="Peter Morris" data-source="post: 146419" data-attributes="member: 652"><p>Re: 60 Degree DIY Mid Hi</p><p></p><p></p><p></p><p><span style="font-size: 10px">Hi Raimonds,</span></p><p><span style="font-size: 10px"></span></p><p><span style="font-size: 10px"></span><span style="font-size: 10px">One of the biggest issues for me has been trying to develop crossover and correction EQ settings for the DIY.</span></p><p><span style="font-size: 12px"><span style="font-size: 10px"></span></span></p><p><span style="font-size: 12px"><span style="font-size: 10px">I wanted:</span></span></p><p><span style="font-size: 12px"></span></p><p><span style="font-size: 12px"><span style="font-size: 10px">- Flat phase and amplitude response </span></span></p><p><span style="font-size: 12px"><span style="font-size: 10px">- Excellent time domain behaviour</span></span></p><p><span style="font-size: 12px"><span style="font-size: 10px">- Well controlled directivity especially in the horizontal plane. </span></span></p><p><span style="font-size: 12px"><span style="font-size: 10px"></span></span></p><p><span style="font-size: 12px"><span style="font-size: 10px">Most people think that a flat amplitude response measured at the Front of House (FOH) mixing position is what is required. I often hear the results of this approach and it’s not good.</span></span></p><p><span style="font-size: 12px"><span style="font-size: 10px">It does not allow for the effect boundaries have on the response, that we expect some HF roll off with distance, and that the measurement system does to match how we process and hear sound. </span></span></p><p><span style="font-size: 12px"><span style="font-size: 10px"></span></span></p><p><span style="font-size: 12px"><span style="font-size: 10px">Toole’s paper discusses some of this and it seem to align with what I expected … i.e. Most people like 6-8 dB LF boost and a little HF roll off with distance; that’s what sounds natural. Flat (measured at FOH) will sound harsh … it is all of course dependant on the particular space you are in and your personal preference.</span></span></p><p><span style="font-size: 12px"><span style="font-size: 10px"></span></span></p><p><span style="font-size: 12px"><span style="font-size: 10px">The conclusion I have come to is you should EQ the speaker flat as measured in an anechoic chamber … (if you can find one that’s big enough and goes low enough). You may need to make a few minor adjustments as a result of the directivity not being perfect so you still archive the best compromise in a "perfect" room (whatever that is).</span></span></p><p><span style="font-size: 12px"><span style="font-size: 10px"></span></span></p><p><span style="font-size: 12px"><span style="font-size: 10px">In a real room there will be resonate modes with a reverberate field that is not consistent across the frequency spectrum. You will of course need to make system EQ adjustments to find the best compromise for each different room.</span></span></p><p><span style="font-size: 12px"><span style="font-size: 10px"></span></span></p><p><span style="font-size: 12px"><span style="font-size: 10px">Unfortunately the best I have been able to do is fly the speaker so they are far enough away from any boundaries relative to the lowest frequency I’m trying to measure…. and listen.</span></span></p><p><span style="font-size: 12px"><span style="font-size: 10px"></span></span></p><p><span style="font-size: 12px"><span style="font-size: 10px">I also took note of one of Earl Geddes papers where he suggests that horizontal pattern control was more important that the vertical pattern because of our hearing mechanism. He also suggested that a speaker's direct response and power response should match between 700Hz – 7000Hz … Although he is concerned with HiFi speakers I’m inclined to agree with his logic with respect to PA speakers..</span></span></p><p><span style="font-size: 12px"></span></p><p><span style="font-size: 12px"></span><span style="font-size: 10px"><a href="https://www.youtube.com/watch?v=fE2nWVwFT9k" target="_blank">https://www.youtube.com/watch?v=fE2nWVwFT9k</a></span></p><p><span style="font-size: 12px"><span style="font-size: 10px"></span></span></p><p><span style="font-size: 12px"><span style="font-size: 10px">Check out the directivity curve on the 60 degree horn I used. Also note that at the crossover point the directive of the LF section (dipole) has an impact and should result in an even better DI.</span></span></p><p><span style="font-size: 12px"></span><span style="font-size: 10px"><a href="http://www.eighteensound.it/PRODUCTS/Products/CatID/5/ProdID=180#.VkM-GmkbraQ" target="_blank">http://www.eighteensound.it/PRODUCTS/Products/CatID/5/ProdID=180#.VkM-GmkbraQ</a></span></p><p><span style="font-size: 12px"><span style="font-size: 10px"></span></span></p><p><span style="font-size: 12px"><span style="font-size: 10px">With respect to the time domain issues and identify resonances etc, your TDA program was most helpful (thank you). The fundament design criteria was to have all of the drivers operating in their piston range. This helps in eliminating many of the time domain problems that can occur. It also means that any lumps and bumps in the frequency response can be corrected perfectly with EQ without causing other issues. </span></span></p><p><span style="font-size: 12px"></span><span style="font-size: 10px"></span></p><p><span style="font-size: 10px"></span></p><p><span style="font-size: 10px"></span></p></blockquote><p></p>
[QUOTE="Peter Morris, post: 146419, member: 652"] Re: 60 Degree DIY Mid Hi [SIZE=2]Hi Raimonds, [/SIZE][SIZE=2]One of the biggest issues for me has been trying to develop crossover and correction EQ settings for the DIY.[/SIZE] [SIZE=3][SIZE=2] I wanted:[/SIZE] [SIZE=2]- Flat phase and amplitude response [/SIZE] [SIZE=2]- Excellent time domain behaviour[/SIZE] [SIZE=2]- Well controlled directivity especially in the horizontal plane. [/SIZE] [SIZE=2] Most people think that a flat amplitude response measured at the Front of House (FOH) mixing position is what is required. I often hear the results of this approach and it’s not good.[/SIZE] [SIZE=2]It does not allow for the effect boundaries have on the response, that we expect some HF roll off with distance, and that the measurement system does to match how we process and hear sound. [/SIZE] [SIZE=2] Toole’s paper discusses some of this and it seem to align with what I expected … i.e. Most people like 6-8 dB LF boost and a little HF roll off with distance; that’s what sounds natural. Flat (measured at FOH) will sound harsh … it is all of course dependant on the particular space you are in and your personal preference.[/SIZE] [SIZE=2] The conclusion I have come to is you should EQ the speaker flat as measured in an anechoic chamber … (if you can find one that’s big enough and goes low enough). You may need to make a few minor adjustments as a result of the directivity not being perfect so you still archive the best compromise in a "perfect" room (whatever that is).[/SIZE] [SIZE=2] In a real room there will be resonate modes with a reverberate field that is not consistent across the frequency spectrum. You will of course need to make system EQ adjustments to find the best compromise for each different room.[/SIZE] [SIZE=2] Unfortunately the best I have been able to do is fly the speaker so they are far enough away from any boundaries relative to the lowest frequency I’m trying to measure…. and listen.[/SIZE] [SIZE=2] I also took note of one of Earl Geddes papers where he suggests that horizontal pattern control was more important that the vertical pattern because of our hearing mechanism. He also suggested that a speaker's direct response and power response should match between 700Hz – 7000Hz … Although he is concerned with HiFi speakers I’m inclined to agree with his logic with respect to PA speakers..[/SIZE] [/SIZE][SIZE=2][URL]https://www.youtube.com/watch?v=fE2nWVwFT9k[/URL][/SIZE] [SIZE=3][SIZE=2] Check out the directivity curve on the 60 degree horn I used. Also note that at the crossover point the directive of the LF section (dipole) has an impact and should result in an even better DI.[/SIZE] [/SIZE][SIZE=2][URL]http://www.eighteensound.it/PRODUCTS/Products/CatID/5/ProdID=180#.VkM-GmkbraQ[/URL][/SIZE] [SIZE=3][SIZE=2] With respect to the time domain issues and identify resonances etc, your TDA program was most helpful (thank you). The fundament design criteria was to have all of the drivers operating in their piston range. This helps in eliminating many of the time domain problems that can occur. It also means that any lumps and bumps in the frequency response can be corrected perfectly with EQ without causing other issues. [/SIZE] [/SIZE][SIZE=2] [/SIZE] [/QUOTE]
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