longdrive03 Posted September 27, 2007 Share Posted September 27, 2007 See the below thread about my initials questions and responses. Please tell me where I'm going wrong on the below plan. I think I'll take a trial run at the Super Heresy with 2 KP-22-E woofers per side, another brand mid driver (either on a K-703 horn or a 5 x 15" horn) and a K-79-K tweeter. DJK suggested in the below thread a 6 cf box SBB4 alignment with some eq tuned to around 30 hz. I've got 2 T2A autoformers that I'll use on the mid which is supposedly 110db 1w/1m. The KP-22-E measures 94.99 db on my WT2 so I should get 6 more db wiring two in parallel for 4 ohm load and using close placement. Looks like I'll need about 9db attenuation from the T2A using tap 2. I understand this tap has a factor of 8 times the driver impedance (17.5 at 750Hz) for 140 ohm so I'll use a 1.5uf cap before the T2A per the HII xover layout. The HII xover shows a 2.5mh coil and 68uf cap so I'll use a 1.25mh coil and 136uf cap for the dual woofers. I'll use the HII 18db on the tweeter (double 1.5uf and .16mh coil). Any problems with using double 2 uf with the .16mh coil like the KLF20 uses with the K-79 tweeter for a slightly lower xover point? Questions: Does anyone know the impedance of the 2.5mh coil in the HII design? Seems like I saw somewhere that it was around .3 ohms? By reducing to a 1.25mh what impedance should I look for on the coil? What about baffle step correction - does it need it? Internal cabinet size will probably be 48" tall, 15" wide and 15" deep (with some possible variation of the width and/or depth? Any suggestions on how high to place the bottom woofer on the front baffle? Gosh this guy asks a lot of questions! I know with all the technical know how on this forum some kind soul can help. Please feel free to show me the error of my ways and criticize, suggest, or boo at will. Thanks. Quote Link to comment Share on other sites More sharing options...
DrWho Posted September 27, 2007 Share Posted September 27, 2007 The only thing I might suggest is investing a little bit in some measurement equipment so that you can make sure your crossovers are working as intended. Changing taps on the autoformer is going to change the phase a bit. Moving the acoustical centers (dual woofers versus single) is also going to change the phase a bit depending on the axis you choose to align the system. Different drivers should have similar phase if the amplitude response is the same, but slight amplitude variations could dictate different EQ in the filters and then you end up with different phase again. I mention the phase thing because if you don't have perfect phase alignment through the crossover passband, you're going to end up with big holes in the response (not to mention wacky polars). Shouldn't the crossover frequency on a Heresy be low enough to employ an all pass filter on the LF to help time align the woofer to the squawker? I have no experience with these filters, but they sound promising if I'm understanding them correctly. Anyways, there really is no reason you couldn't just go with an entirely new design, but I think your proposed approach should sound decent too. I guess the real question is how crazy do you want to get? Quote Link to comment Share on other sites More sharing options...
djk Posted September 27, 2007 Share Posted September 27, 2007 "The HII xover shows a 2.5mh coil and 68uf cap so I'll use a 1.25mh coil and 136uf cap for the dual woofers. " The HII woofer is 4R, The K22E is 8R, so two K22E should use the same filter as the HII. "Shouldn't the crossover frequency on a Heresy be low enough to employ an all pass filter on the LF to help time align the woofer to the squawker?" Try two 0.35mH and two 12uF. Quote Link to comment Share on other sites More sharing options...
longdrive03 Posted October 1, 2007 Author Share Posted October 1, 2007 DJK: If the 2.5mh and 68uf filter is for a 4 ohm woofer then a 5mh and 34uf filter would be correct for a single KP-22-E since it's an 8 ohm woofer? Correct? Likewise, if you use a 2.5mh and 68uf filter on a single KP-22-E (8 ohm) woofer the xover point will be idoubled (approximately 1500 hz) instead of the 750Hz for the HII??? Correct? I used a 2.5mh 68uf filter on one KP-22 -E so I think I need to change to 5mh and 34uf to get the right xover point. Quote Link to comment Share on other sites More sharing options...
longdrive03 Posted October 3, 2007 Author Share Posted October 3, 2007 Are you suggesting a 24db with two .35mh instead of the 2.5mh coil and 68uf cap for the two KP-22-E (4ohms)??? Quote Link to comment Share on other sites More sharing options...
djk Posted October 3, 2007 Share Posted October 3, 2007 "Are you suggesting a 24db with two .35mh instead of the 2.5mh coil and 68uf cap for the two KP-22-E (4ohms)???" No,the extra parts are an allpass filter (time delay). Quote Link to comment Share on other sites More sharing options...
longdrive03 Posted October 3, 2007 Author Share Posted October 3, 2007 Where do you place them in relation to the 2.5mh coil and 68uf cap? Quote Link to comment Share on other sites More sharing options...
djk Posted October 4, 2007 Share Posted October 4, 2007 For a manufacturer the unbalanced is best, one half-sized inductor (bi-filar) and half the capacitor count. Not having ready access to bi-filar inductors, the home constructor is better off using the balanced version. The filter goes between the crossover network and the driver. http://i56.photobucket.com/albums/g196/dkleitsch/all-pass.gif'> Quote Link to comment Share on other sites More sharing options...
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