Infinity crossover coil value
in [Repair]
|
From: BOB Urz "sound" on 20 Jan 2007 00:14 Ross Herbert wrote: > On Fri, 19 Jan 2007 18:36:48 -0600, BOB Urz <"sound"@(remove) > inetnebr.com> wrote: > > >I had a customer bring in an Infinity KPX00 crossover for a 6.5" car > >unit. Coil L2 has burnt marks on it, Its a 24db linkquitz riley filter > >(or so the spec sheet says). > >Customer claims low tweeter output > > > >http://manuals.harman.com/INF/CAR/Owner's%20Manual/KAPPA%20PERFECT%206-1%20om.pdf > > > >in: > >(+) > >-------| > > | > > == C=15.7ufd > > | C=14ufd R=(1,2,4) OUTPUT > > |------------][------------/\/\/\/\/\------| > > > | > > >L2 (burnt) | > > > * > >(tweeter) > > | * > > | | > >------------------------------------------------ > >(-) (-) > > > >So, the input is a series cap inductor combination with a 15.7 MFD and > >unknown coil in series with the amp. The center tap of the two feeds a > >14MFD cap and then goes through a series resistor adjustable pad > >to the tweeter. I tried to read the coil on my sencore, and it measures > >about .3 MH. It won't pass any ring test (air core) so i know turns are > >shorted and this value is suspect. Any clue on the value of this coil? > > > >Strange, this seems to be a 3rd order filter rather than what the tear > >sheets says. > >Only one coil on the high pass with two caps. > >Minus the pad, it looks like the 3rd order 18 DB filter here: > > > >http://www.apicsllc.com/apics/Misc/filter2.html > > > >and these calculated 3500hz values are (4 ohm nominal) > >C=7.5 ufd > >L=0.1364 mh > >C2=22.7 > > > >standard replacement coil values are .1,.13,.15,.20,.27,.33 and etc. > > > >Thoughts? > > > >Bob > > > > > >----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==---- > >http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups > >----= East and West-Coast Server Farms - Total Privacy via Encryption =---- > > I would be rather concerned about what actually caused the inductor/s > to be cooked so badly. Assuming you managed to replace them and get it > going again, what's to say that the owner is not going to repeat the > exercise? > > He would have to be driving these things extremely hard to cause the > burnouts so perhaps they are not matched to his amps power output and > speakers correctly or he is running both amp and speakers into severe > overload. In this case I would suspect that the speakers aren't in too > good a shape either. The drivers are intact. Yes, i believe they were driven hard. But i am not the sound police. Only the repair man. So he wants the crossovers fixed and i will fix them if i can. But if he fry's them again its on his dime. I didn't design them and did not overdrive them. Bob ----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =----
From: BOB Urz "sound" on 20 Jan 2007 00:19 Arny Krueger wrote: > "BOB Urz" <"sound"@(remove) inetnebr.com> wrote in message > news:1169258413_9495(a)sp6iad.superfeed.net > > Richard Crowley wrote: > > > >> "BOB Urz" < wrote ... > >>> I had a customer bring in an Infinity KPX00 crossover > >>> for a 6.5" car unit. Coil L2 has burnt marks on it, > >> > >> You can't measure (or observe) the one on the other side? > > > > While not quite symmetric, the other channels crossovers > > coil is burnt worse than the one i am looking at now. So, no > > chance for a good part measurement. > > How badly burnt? > > I've seen some pretty ugly messes based on an heavy-gauge wire choke that > was still OK. > > For openers, unless they were burnt open or fused, I'd measure both coils > and see if they still measure the same. > > On a really bad day, wind up a coil of the same gauge wire and same number > of turns in the same form factor and measure it. Given unlimited time and doing it for the sake of doing it, the coil could be rewound by determining the size of wire, buying a spool, counting the turns of the old coil and trying to duplicate it. Its an exercise in wasting a lot of time. I just need to get a value and throw in another coil. Preferably, of a bigger wire size so it might be more robust. (my guess is 20g on this one) When i can get no rings out of them on the sencore, you can about guarantee some turns are shorted. Bob ----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =----
From: Ross Herbert on 20 Jan 2007 00:43 On Fri, 19 Jan 2007 23:14:01 -0600, BOB Urz <"sound"@(remove) inetnebr.com> wrote: >> I would be rather concerned about what actually caused the inductor/s >> to be cooked so badly. Assuming you managed to replace them and get it >> going again, what's to say that the owner is not going to repeat the >> exercise? >> >> He would have to be driving these things extremely hard to cause the >> burnouts so perhaps they are not matched to his amps power output and >> speakers correctly or he is running both amp and speakers into severe >> overload. In this case I would suspect that the speakers aren't in too >> good a shape either. > >The drivers are intact. Yes, i believe they were driven hard. >But i am not the sound police. Only the repair man. >So he wants the crossovers fixed and i will fix them if i can. >But if he fry's them again its on his dime. I didn't design them >and did not overdrive them. > >Bob > I entirely agree Bob. I was trying to intimate that perhaps along with carrying out the wishes of the owner to repair these things, that a little education might be needed to avoid a repeat. If he doesn't want to heed your warnings, then sure, repair them as often as needed - it's his money he's burning. The only caution with this procedure may be that when his speakers (or the amps) eventually do clap out he may try to blame you for their demise by saying you can't possibly have repaired the x-overs correctly because they hadn't died at the time the x-over first failed, so why should they have died after you repaired them. You can't reason with some people.
From: Arny Krueger on 20 Jan 2007 06:36 "BOB Urz" <"sound"@(remove) inetnebr.com> wrote in message news:1169270006_10549(a)sp6iad.superfeed.net > When i can get no rings out of them on the sencore, you > can about guarantee some turns are shorted. That appears to be self-contradictory. Are you trying to saythat even though the coils pass a shorted-turn test, you still think they are too far gone to be worth measuring?
From: Bob Urz on 20 Jan 2007 11:50
Arny Krueger wrote: > "BOB Urz" <"sound"@(remove) inetnebr.com> wrote in message > news:1169270006_10549(a)sp6iad.superfeed.net > > >>When i can get no rings out of them on the sencore, you >>can about guarantee some turns are shorted. > > > That appears to be self-contradictory. > > Are you trying to saythat even though the coils pass a shorted-turn test, > you still think they are too far gone to be worth measuring? > > You DON'T understand Arny. Rings are GOOD on the sencore test. Low ring count or NO ring count means the coil is shorted. http://www.freepatentsonline.com/5717338.html This coil would show NO rings on the inductor ring test. Its shorted. If its shorted, the measured value of inductance is not going to be accurate. The ultimate solution is use the crossover circuit topography with the listed value of caps and known crossover point (3500hz) and use algebra to solve for the inductor value (solve for one unknown). I have been too busy to try to figure that out. I also don't know why the tear sheets says its a 24db filter, when the hand drawn schematic from the crossover does not show that. It would need another inductor for that. With two caps and a inductor, it appears to be a 3rd order. I have barely a few hours in the shop before i have to head off to set up for Jeff Daniel's and do FOH sound for two shows today. Maybe someone with a lot of time on there hands can ID the filter from the ascii drawing, and find the math to reverse engineer the inductor value. There's a challenge for you Arny if your up to it. I am guessing its in the .13 range at this point. Bob ----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |