whtboy Posted January 11, 2006 Share Posted January 11, 2006 I've done some searching but haven't found any impedance vs. frequency plots for the K55 or K77 drivers. Does anyone know where I could find some? I don't have any highend test equipment. Thanks! -jacob Quote Link to comment Share on other sites More sharing options...
BEC Posted January 11, 2006 Share Posted January 11, 2006 Here is what I measured on a K-55V and K-55M. Bob Crites k-55mimp.pdf Quote Link to comment Share on other sites More sharing options...
whtboy Posted January 11, 2006 Author Share Posted January 11, 2006 Does the impedance on a midrange driver not vary as much as on a woofer normally? Or perhaps it doesn't get really ugly until you reach frequencies below where the mid would normally operate anyway? I was expecting it to be all over the place. Thanks Bob!!! -jacob Quote Link to comment Share on other sites More sharing options...
whtboy Posted January 11, 2006 Author Share Posted January 11, 2006 Uh, scratch that. I didn't see the big peaks until I started entering the numbers into Excel. Plots coming shortly! -jacob Quote Link to comment Share on other sites More sharing options...
whtboy Posted January 11, 2006 Author Share Posted January 11, 2006 I can't get these Excel charts to work to save my life. I'm guessing there isn't a way to get it to interpret the X-axis on a logarithmic scale. I put the numbers into a worksheet and made a chart of the values below 2kHz if anyone is interested. Are there any free tools out there that can generate plots with a logarithmic X-axis? -jacob Quote Link to comment Share on other sites More sharing options...
whtboy Posted January 11, 2006 Author Share Posted January 11, 2006 Bob, Do you know what the stock crossover points are on a stock Cornwall I? -jacob Quote Link to comment Share on other sites More sharing options...
Jeff Matthews Posted January 11, 2006 Share Posted January 11, 2006 I see you're working at it, Jacob. Let me know when you're done. Make a new post. Quote Link to comment Share on other sites More sharing options...
BEC Posted January 11, 2006 Share Posted January 11, 2006 Would be about 600 and 6000 or so. Pretty gentle slope on the cross from mid to tweet, so depends a lot on how you look at it. Bob Crites Quote Link to comment Share on other sites More sharing options...
whtboy Posted January 11, 2006 Author Share Posted January 11, 2006 Cool, thanks Bob! Can't wait to get my new diaphragms and caps in! -jacob Quote Link to comment Share on other sites More sharing options...
Deang Posted January 11, 2006 Share Posted January 11, 2006 "I was expecting it to be all over the place."Impedance IS all over the place. Those numbers are just of the K-55 without a horn or network attached. The K-55-V is an Atlas Sound PD5-VH. Spec sheet with raw impedance plot of the driver attached. Atlas PD5-VH-VT.PDF Quote Link to comment Share on other sites More sharing options...
BEC Posted January 11, 2006 Share Posted January 11, 2006 Dean, Those K-55s I tested were on a K-400 horn. Bob Quote Link to comment Share on other sites More sharing options...
WMcD Posted January 11, 2006 Share Posted January 11, 2006 I always find Excel charts a bit of a challenge. If you right click on the x axis you bring up a format x axis dialog box. Then you find an option for log scale. My guess is that the impedance plot is for a horn attached. The leftmost peak is the diaphragm resonance. This is just like a sealed box woofer where the diaphrage resonance causes an impedance peak. This is like a mini woofer. The one farther right and then the next smaller one even farther right are impedance peaks caused by the horn itself. You see the peaks in the plots of acoustic throat impedance .of horn by Harry Olson. Gil Quote Link to comment Share on other sites More sharing options...
whtboy Posted January 11, 2006 Author Share Posted January 11, 2006 Excellent! Thanks for the tip. This is looking much better now. Yes, according to the pdf Bob wrote up it appears the driver was loaded in a K400 horn for the test. Is it common for drivers to have really uneven impedance plots like this? -jacob EDIT: man, microsoft sure makes some great office applications. too bad they don't stick to what they know and just leave operating system design to the cs engineers =) Quote Link to comment Share on other sites More sharing options...
whtboy Posted January 11, 2006 Author Share Posted January 11, 2006 I'm curious how much the impedance plots vary between drivers of the same model. EDIT: Bob, were there any other components (such as part of a crossover) in the circuit when you did the test, or is this the raw plot of the driver on the wire? Quote Link to comment Share on other sites More sharing options...
Al Klappenberger Posted January 12, 2006 Share Posted January 12, 2006 Guys, Here's my Zo plot of the K55V BTW: "V/V" on the left edge means 0-20 Ohms. On the other plot (K77) it's 0-10 Ohms. The upper plot is the reactive "phase" component of the impedance. + means inductive, - means capacitive. It's inductive (of course).Al K. Quote Link to comment Share on other sites More sharing options...
Al Klappenberger Posted January 12, 2006 Share Posted January 12, 2006 Here's the K77 tweeter: Al K. Quote Link to comment Share on other sites More sharing options...
Deang Posted January 12, 2006 Share Posted January 12, 2006 Cornwall II with network. Quote Link to comment Share on other sites More sharing options...
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