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Shootout: KF650e vs DX1565
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<blockquote data-quote="Silas Pradetto" data-source="post: 57001" data-attributes="member: 34"><p>Re: Shootout: KF650e vs DX1565</p><p></p><p></p><p></p><p>Hi Ivan, this is a very good question and I didn't really answer it in my OP. In this particular case, maximum output is more closely related to 'maximum overall sensitivity'. Here's why:</p><p></p><p>The amplifiers used to power these boxes for this demo provide 1250 watts into an 8 ohm nominal load. I did not impedance sweep the boxes to determine exactly how much power was being used under the measurement conditions. The thought process that went into these measurements was like this - both the LF sides of things were rated at less continuous wattage than the amplifier can deliver. The Fulcrum is rated 700W and the KF650 rated 1000W on the LF side. Both the MF/HF sides are rated less than the amplifier output as well - Fulcrum being 350W and the KF650 being 400W. I set the limiters on the amp to these values, based on the voltage formula. When taking the measurements, my goal was to measure in the same way that Fulcrum does, "increasing output until any one subsection of the box is driven to full rated power." However, the amp didn't provide enough voltage/wattage to actually comply with this requirement, meaning the amp clipped before any subsection was driven to full rated power. With a 6dB crest factor pink noise stimulus, I'd need 6dB above rated power of each passband to get to this point, so I'd need an amp capable of 2800 or 4000 watts at 8 ohms on the LF, and 1400 or 1600 watts at 8 ohms for the HF sides of things. In this case I only had 1250 available, so I pretty much expected the amp to run out of headroom first. </p><p></p><p>The difference between 1250 and 1600 or 1400 watts is very minimal - about 1dB. Since both boxes ran out of headroom on their MF/HF bands far before the LF bands, just due to the way 'flat' needs to be EQ'd, the fact that the LF sections had a ton of headroom didn't really matter. So both boxes were driven to within 1dB of their maximum output when the amp clipped. </p><p></p><p>Hopefully that answers the question - when the boxes were driven to amp clipping with pink noise, things still sounded good; nothing sounded like it would explode. I was wearing ear muffs so my ear certainly wasn't distorting. Under an actual music program things may have ended up differently, but the measurements I took matched well with the paper specs of both boxes. Fulcrum says 131dB continuous for the DX1565, and EAW claims 139dB peak for the MF of the 650, so removing 6dB for their continuous spec, they'd be 131 vs 133dB. Seems to match up pretty well.</p></blockquote><p></p>
[QUOTE="Silas Pradetto, post: 57001, member: 34"] Re: Shootout: KF650e vs DX1565 Hi Ivan, this is a very good question and I didn't really answer it in my OP. In this particular case, maximum output is more closely related to 'maximum overall sensitivity'. Here's why: The amplifiers used to power these boxes for this demo provide 1250 watts into an 8 ohm nominal load. I did not impedance sweep the boxes to determine exactly how much power was being used under the measurement conditions. The thought process that went into these measurements was like this - both the LF sides of things were rated at less continuous wattage than the amplifier can deliver. The Fulcrum is rated 700W and the KF650 rated 1000W on the LF side. Both the MF/HF sides are rated less than the amplifier output as well - Fulcrum being 350W and the KF650 being 400W. I set the limiters on the amp to these values, based on the voltage formula. When taking the measurements, my goal was to measure in the same way that Fulcrum does, "increasing output until any one subsection of the box is driven to full rated power." However, the amp didn't provide enough voltage/wattage to actually comply with this requirement, meaning the amp clipped before any subsection was driven to full rated power. With a 6dB crest factor pink noise stimulus, I'd need 6dB above rated power of each passband to get to this point, so I'd need an amp capable of 2800 or 4000 watts at 8 ohms on the LF, and 1400 or 1600 watts at 8 ohms for the HF sides of things. In this case I only had 1250 available, so I pretty much expected the amp to run out of headroom first. The difference between 1250 and 1600 or 1400 watts is very minimal - about 1dB. Since both boxes ran out of headroom on their MF/HF bands far before the LF bands, just due to the way 'flat' needs to be EQ'd, the fact that the LF sections had a ton of headroom didn't really matter. So both boxes were driven to within 1dB of their maximum output when the amp clipped. Hopefully that answers the question - when the boxes were driven to amp clipping with pink noise, things still sounded good; nothing sounded like it would explode. I was wearing ear muffs so my ear certainly wasn't distorting. Under an actual music program things may have ended up differently, but the measurements I took matched well with the paper specs of both boxes. Fulcrum says 131dB continuous for the DX1565, and EAW claims 139dB peak for the MF of the 650, so removing 6dB for their continuous spec, they'd be 131 vs 133dB. Seems to match up pretty well. [/QUOTE]
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