Four KM-84 Clones - Blind Test

[joulupukki]

Interesting. So with C2 at 2.2/3.9pF the high pass frequency shifts even higher? …and the mic would have an even higher sensitivity in the high end?

Ignore that question. I loaded those same .mdat files in REW and now understand what you mean. I should put in a pad capacitor in C2 in the MP mic and see what ends up happening in real life recordings. Ah, except I don’t wanna touch those tiny screws in that mic body again. I need to find some replacements. When I first started with those mics I wasn’t delicate enough and I ended up nearly ruining the slot on the screw head. :-|

 

[joulupukki]

I don't know if anyone else will find this interesting, but since I can't currently record all 6 microphones at the same time (because I need to get some better XLR connectors), I decided to see how pink noise is recorded by each of them. In the following image, what you'll see is that the KM84+ is used as the "base" EQ. I used FabFilter's Pro-Q3 to do an EQ match with the KM84+ recording pink noise.

If you see the yellow line going UP past zero, that means that in order to sound like the KM84+, the mic EQ has to be raised at that point. Lower than 0 means the EQ at the given frequency has to be lowered.

Something else interesting (confirming what I'm hearing) is that I swapped the MP SDC-84 capsule for a 3U Audio Capsule and did a recording with the MP SDC-84 of pink noise. See the big drop at the high end frequencies on the stock MP SDC-84 capsule?

With the KM84++ I'm seeing that the low end needs to be raised to match the KM84+. Also, like I can hear in the recordings, 5-15kHz has to be raised in order to match the KM84+ ... confirming why I'm not hearing as much definition out of the KM84++ as the KM84+.

This also includes the stock Takstar CM-60 and CM-63 and it's interesting to see that they both have a mid scoop compared with the KM84+. The CM-63 has a lot more high end above 8kHz compared with the KM84+. When I was comparing the CM-60 earlier this year against my Graeme Woller KM84 build, the CM-60 sounded really close except it had significantly more low end.

 

[jp8]

Interesting. So with C2 at 2.2/3.9pF the high pass frequency shifts even higher? …and the mic would have an even higher sensitivity in the high end?

No, maybe my description wasn't clear, but it's actually the other way around. The green line shows low-end roll-off with C2 = 0 pF and roll-off point moves to the left to a lower frequency.

Gain (or sensitivity) increases when C2 decreases and is limited by the open-loop gain of the JFET.

Jan

 

[joulupukki]

I fixed up the commercial XLR cables I had by pulling them apart and re-soldering the broken wires. I should have thought of doing that long ago. They should now last a much longer time.

Logistically, how could I best record 6 microphones at once? I've got 4 of them plugged in to a Zoom H6 and 2 of them into the Apollo Twin X but ...

They are now spread out far enough that I'm not sure that it's gonna be a fair enough comparison because I know even some movement of mic position on a source can make a difference. Thoughts? Here's my crazy makeshift mic clip. In initial recordings the stock Takstar mics definitely have less definition than all of the others and I can hear the mid scoop in them.

 

[kingkorg]

I fixed up the commercial XLR cables I had by pulling them apart and re-soldering the broken wires. I should have thought of doing that long ago. They should now last a much longer time.

Logistically, how could I best record 6 microphones at once? I've got 4 of them plugged in to a Zoom H6 and 2 of them into the Apollo Twin X but ...

They are now spread out far enough that I'm not sure that it's gonna be a fair enough comparison because I know even some movement of mic position on a source can make a difference. Thoughts? Here's my crazy makeshift mic clip. In initial recordings the stock Takstar mics definitely have less definition than all of the others and I can hear the mid scoop in them.

View attachment 140014

They are both spread between each other, and they obstruct each other's vents significantly. It is best to put each one on a stand in same position, same distance from the source, play same exact clip of pink noise, or some other material. Noise is most revealing tho. Even if you make couple millimeters of error in positioning it will be less than this.

 

[jp8]

How about using a stereo mic bar with those long slots for positioning the mics? Add 4 more screws, if you can find them. Then mount the mics as if in a line array, but then in a concave shape. Sound source positioned in the focal point. Perhaps flip the bar and record for a second time. Upper mic, which becomes lower mic in second take, should sound identical in both takes to confirm that sound field is symmetrical around the center of the bar.

Jan

 

[joulupukki]

Yeah, good points. Ideally I'd like to record the exact same thing with all of the mics at once since it'd be the same performance. I used to have a nice stereo bar that came with the SE Electronics sE5 Stereo Pair I had, but sold the whole thing after I realized I liked these KM-84 variants a LOT more.

Maybe to get the general idea of these mics I could just record them two at a time and try the best I can to keep the same mic placement and similar performance volume on each of the instruments. Since it'll be a little longer than a 10-second passage the mic characteristics would better be heard for each one. If I stay about 16" away from the mics when recording I could probably do them two at a time and the distance between two mics would more or less be negligible.

Sorry to say, but the blind test from post #1 was done with 4 of these mics being taped closely together. But, each mic had that "disadvantage" so it's not like one of them had it "better" than the other. Definitely not ideal, but for the experiment it did allow a decent capture of the mic characteristics.