Head-Fi.org › Forums › Misc.-Category Forums › DIY (Do-It-Yourself) Discussions › K1000 impedance curve?
New Posts  All Forums:Forum Nav:

K1000 impedance curve?

post #1 of 13
6/8/05 at 8:16pm
Thread Starter 
Has anyone measured the impedance of the K1000 over the full spectrum?
If yes, would you mind sharing the graph or the .txt .zma or whatever format your measurement rig outputs?
Thanks
Reply
post #2 of 13
6/8/05 at 8:33pm
im willing to bet that it is nearly flat.

based on the freq response curve of the driver...

i do not know this to be fact though. it is an assumption.

do you have an osciloscope, and a waveform generator? it is not hard at all to test freq vs impedance with those 2 bits of gear and a resistor.
Reply
post #3 of 13
6/8/05 at 9:00pm
update:

if you are thinking of optomising crossover points, build up a active network.

i am assuming that this is the case, based on this thread:thread of yesteryear

with an active crossover, peculiar slopes are easy, phase distortions are easier to deal with, parts are cheaper (umm, price a GOOD cap for a 20 hz high pass passive vs the components for a similarly sounding active x-over) and lastly, drivers that vairy TREMENDOUSLY with frequency dont effect the x-over points or slopes.
Reply
post #4 of 13
6/8/05 at 9:41pm
I did measure the K1000 impedance. This was posted in another thread from a while ago -



Cheers,
Joe
Reply
post #5 of 13
6/8/05 at 10:08pm
Thread Starter 
thanks for your interest in the subject. I do have something cooking and hopefully will show it soon. I do have a way of measuring impedance (software and a pro card), but my jig is not ready yet. I guess it's time to actually solder it up.

Yes, I want to make a passive circuit and need the exact impedance for the sim.

"phase distortions are easier to deal with"

phase is phase regardless of the nature of crossover (active or passive). The same frequency response will result in the same phase response (in a minimum phase system, which individual active and passive filters are- just ask mr. Hilbert)

"parts are cheaper (umm, price a GOOD cap for a 20 hz high pass passive vs the components for a similarly sounding active x-over)"

I was thinking more in terms of shaping the top end. But even the low end is not all that bad once you consider the load. It takes some big caps and coils at 4-8 ohms, 120 ohm is much more doable.

"and lastly, drivers that vairy TREMENDOUSLY with frequency dont effect the x-over points or slopes."

Yes, that's why I asked if anyone measured the impedance. If it varies wildly, a simple circuit I was considering might not work. But if it it indeed is fairly flat as you indicated in your first post, then I would like to give it a shot.
Reply
post #6 of 13
6/8/05 at 10:11pm
Thread Starter 
Quote:
Originally Posted by Joe Woj
I did measure the K1000 impedance. This was posted in another thread from a while ago -



Cheers,
Joe
Thanks Joe, This is very nice. I can use the trace program to capture the values. Or, if you saved the txt file from Audio Precision and still have it, maybe you could email it to me?
jan@thuneau.com
Reply
post #7 of 13
6/8/05 at 10:45pm
I don't think I saved the ASCII output for this test. However, it's pretty easy to redo. I can re-run the test tomorrow and ship you the data. How many data points do you want and over what frequency range do you want measured? This graph was 512 data points.

Joe
Reply
post #8 of 13
6/8/05 at 11:09pm
Thread Starter 
You know, I just used the SPL trace program from FRD Consortium and got a vey good .zma that I can use in my lspCAD program.
So, no real need to email me the results. But, seeing how high the impedance peaks and how it never really gets below 135 Ohm, maybe a confirmation of the results would be in order? Did you measure both sides? If yes, how close are they to eachother?
Should you get somewhat different results this time I would love to get the txt file from you. Thanks.
Reply
post #9 of 13
6/8/05 at 11:31pm
In the usual battery of tests that I use for data posted on our website, I only test the left channel. Like I said, it's pretty easy to re-test so I can confirm the results with an additional run tomorrow. However, this actually looks like a pretty typical headphone impedance curve.

Joe
Reply
post #10 of 13
6/8/05 at 11:46pm
Thread Starter 
I trust your expertise. If you have a minute and don't mind testing them again maybe you can see how good the matching of the transducers is?
I'll take a 500 point zma file then. Thanks.
Reply
post #11 of 13
6/9/05 at 11:19pm
Hi Thuneau,
Sorry about the delay. I got caught up in some glass related issues. I'll have some confirmation and/or data by noon MST Friday. That's tomorrow, right?




Joe
Reply
post #12 of 13
6/10/05 at 12:05pm
Hi Thuneau,
The left/right impedance of the K1000 transducers is matched to within +/-2 ohms on the pair that I tested. The above graph is indeed accurate and I've e-mailed you a comma delimited text file, "AKG_K1000_impedance.adx"

Cheers,
Joe
Reply
post #13 of 13
6/10/05 at 1:39pm
Thread Starter 
Thanks again Joe. You rock!
I ran some sims in my loudspeaker software. The big impedance 200 Ohm swell is no problem. A zobel takes care of it easilly with fairly small cap values.
Reply
New Posts  All Forums:Forum Nav:
  Return Home
Head-Fi.org › Forums › Misc.-Category Forums › DIY (Do-It-Yourself) Discussions › K1000 impedance curve?