Members bigmike216 Posted January 2, 2006 Members Share Posted January 2, 2006 just try the one that's in the cabinet already before you go about making your own. Link to comment Share on other sites More sharing options...
Members dboomer Posted January 3, 2006 Members Share Posted January 3, 2006 Originally posted by tlbonehead Only the middle 15 covers the full 40-2,000hz. With the bottom 15 rolled out at 250hz or so the two drivers are not reproducing the same freq which is good because of the distance they are apart that would cause cancelation. Allot of speaker companies make them this way. Peavey makes a great sp4 speaker and they call this type of box Quasi 3 way if I remember right. The early SP4's used to work like that but the new ones actually crossover about an octave and a half higher. Our engineers developed a special "non-textbook" crossover that treats the bottom woofer seperately so that phase cancellation problems are kept to a minimum. As a result you get more output. Link to comment Share on other sites More sharing options...
Members laidback Posted January 3, 2006 Members Share Posted January 3, 2006 he ought to be thoroughly confused by now! If I understand the original question, you were asking if there was a way to know if the box was originally wired for 4 or 16 ohms. If you thought the original speakers hadn't been changed, the easy way out would be to see if the woofers were wired in series or parallel. Since the original drivers have been changed, I don't think there's a way to know for sure, especially with the xover components inaccessible. If this were my project, I'd decide what impedance I wanted (determined by how the box was going to be used) and buy/build/modify a crossover to get what I needed. (I'd also be sure the 2 woofers weren't overlapping, but that's another subject.) I do agree with the others that you rarely see 16 ohm boxes in PA, so they were "probably" 4 ohms (unless the original drivers were 16 ohm drivers, parallelled to give 8 ohms...not all that likely.) Of course, that doesn't explain how the 2 boxes were then parallelled for 2 ohms, unless maybe they were old enough that they were running off a tube amp. You could abuse some of the robust tube amp designs pretty badly before you let the magic smoke out of the transformer... Link to comment Share on other sites More sharing options...
Members agedhorse Posted January 3, 2006 Members Share Posted January 3, 2006 Originally posted by laidback I do agree with the others that you rarely see 16 ohm boxes in PA, so they were "probably" 4 ohms (unless the original drivers were 16 ohm drivers, parallelled to give 8 ohms...not all that likely.) Of course, that doesn't explain how the 2 boxes were then parallelled for 2 ohms, unless maybe they were old enough that they were running off a tube amp. You could abuse some of the robust tube amp designs pretty badly before you let the magic smoke out of the transformer... There were quite a few early PA amps that could do 2 ohms... the Peavey CS-800 was one from that era. Not many tube amps came equipped w/ 2 ohm taps due to their limited output power. Link to comment Share on other sites More sharing options...
Members moody Posted January 3, 2006 Author Members Share Posted January 3, 2006 Originally posted by laidback he ought to be thoroughly confused by now! I've been around these parts a good long time, it takes more than this to confuse me. Originally posted by laidback I do agree with the others that you rarely see 16 ohm boxes in PA, so they were "probably" 4 ohms (unless the original drivers were 16 ohm drivers, parallelled to give 8 ohms...not all that likely.) Of course, that doesn't explain how the 2 boxes were then parallelled for 2 ohms, unless maybe they were old enough that they were running off a tube amp. You could abuse some of the robust tube amp designs pretty badly before you let the magic smoke out of the transformer... These boxes are probably early 80's I'd say. I know that they were 'originally' 4ohms. I also know that they have been through a bit since then and have been 'rewired' at least once. I have no idea if rewiring comprised of changing the crossover or not, but the obvious change would be to 16ohm?? I do know that the crossovers currently in it do not match the crossovers of other speakers of the same sort that I have seen. Link to comment Share on other sites More sharing options...
Members moody Posted January 3, 2006 Author Members Share Posted January 3, 2006 Ok. Presuming the crossovers don't work at 4ohms. I am wiring these cabs up tonight and I will see. Are there any basic schematics for crossovers around? It sounds like the different signal to the bottom speaker would be advisable and I very much doubt that my current crossover does it. Don't point me to ready made crossovers on american websites because the chances are I won't be able to get them. Link to comment Share on other sites More sharing options...
Members bigmike216 Posted January 3, 2006 Members Share Posted January 3, 2006 Which order crossover slope would you like? Link to comment Share on other sites More sharing options...
Members moody Posted January 3, 2006 Author Members Share Posted January 3, 2006 Originally posted by bigmike216 Which order crossover slope would you like? And you manage to make a liar out of me. I don't know what you mean by order. Is that like a quick or a gradual change? If it helps at all, I think it's a 1" horn, so probably a higher crossover point, but I have no idea really. Link to comment Share on other sites More sharing options...
Members moody Posted January 3, 2006 Author Members Share Posted January 3, 2006 OK. They are wired up. They sound very toppy without much mids, Sounds good flat with an ibanez lespaul recording, not so great for vocals. (plenty of low bass, not much mid, plenty of high. Also got to turn the gain well up to get enough volume out of them. Could well be a hole in the midrange, how do I tell for sure. (I could play a recording of something through them and record it maybe?) Link to comment Share on other sites More sharing options...
Members moody Posted January 3, 2006 Author Members Share Posted January 3, 2006 Ok. I'm thinking that regardless of whether this crossover is right that I'm better off putting together a good one with good components that I can trust. Where do I pick up a schematic? Link to comment Share on other sites More sharing options...
Members agedhorse Posted January 3, 2006 Members Share Posted January 3, 2006 Here's a good start:Crossover design calculator Start with say 1.8kHz (you might call it 1,8kHz down under ) and a slope of 12dB/octave (second order). That will get you a good start. You might also look at 12dB/oct on the high pass filter to the horns and 6dB (just a coil in series with the woofers) on the low pass to the woofers as it's simpler and the mechanical/electrical rolloff of the woofer will push the slope to 12dB soon enough. Link to comment Share on other sites More sharing options...
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