Four KM-84 Clones - Blind Test

[k brown]

the cm4 is an insane buy, almost as good as schoeps (or better than many of their offerings honestly, but not all) for way way less money. it has a few caveats, like that it can't be used in small booths because its vents are sensitive to reflections at 90 degrees, but for performance and field recording? difficult to find a better mic at any price

Weelll . . . that overstates things a tad.

The flatness of the frequency response is their most remarkabe feature; that and the unbeatable value. But they do not have the low self noise and resolution of a Schoeps, or indeed most other mics in that league.

For recording Classical music, they make terrific spot mics; there the flat response is perfect, and the self noise is never an issue.

 

[joulupukki]

My son ordered a pair through the Benelux distributor. If all goes well, we'll have them before X-mas. He used to have a pair of CM2s, but he sold them off, because he found the them sounding utterly boaring...

Jan

I’m on the list to get a pair from this same dealer but probably won’t see them ‘til late in the year or early next year. Will be interesting to put them to work!

 

[IBarfoot]

I must admit I have a number of the previous Line Audio CM3 wide cardioids, they are superb, amazing value for money and never dissapoint.
I used to purchase them direct but sadly Brexit has done for that, being in the UK. I should realy look at buying some of the CM4 by the sound of the comments here.

 

[k brown]

I must admit I have a number of the previous Line Audio CM3 wide cardioids, they are superb, amazing value for money and never dissapoint.
I used to purchase them direct but sadly Brexit has done for that, being in the UK. I should realy look at buying some of the CM4 by the sound of the comments here.

I've never heard that the CM4 sounds any better than CM3. The polar pattern is very slightly different; they only came out with the CM4 because the capsule used in the CM3 became unavailable.

 

[Dylan W]

Ok, here's a bonus blind test! Sorry, no video this time and you'll have to pull down the wav files yourself to listen.

In no particular order, the mics in this test are:

• Microphone Parts SDC-84
• @jp8 KM84+
• @jp8 KM84++
• Takstar CM-60
• Takstar CM-63
• My Graeme Woller KM84 build in a Takstar CM-60 body

I no longer have the KM-184 since I had to return it or I would have included it.

This collection of WAV files contain static mixes from each mic. The instruments in this track are acoustic guitar, mandolin, banjo, and upright bass. No fancy playing, just quick and dirty to get something. The only thing I've done is a little panning and some crude volume balance and automation. Oh, and I did add a tiny bit of room/reverb to all instruments except for the upright bass just so it didn't feel completely dry.

The purpose of this test was for me to see how these microphones sound if I were to stack them in a mix from every instrument. I can hear differences between the mics. It's interesting hearing good / bad qualities based on listening to a particular instrument/mic combo. I wouldn't ever record this way for a real album. Two of these mics I definitely wouldn't use.

I recorded the mics in pairs of two so there are three "performances". Mics 1 and 2 were recorded together as were 3 and 4 ... and 5 and 6. Each mic had its own mic stand and clip with about 1 inch of separation. For guitar they were about 6-8 inches away from where the neck meets the body. Mandolin about 12-14" away – same with banjo (with the mics pointing where the neck meets the banjo head). With upright bass the mics were pointed directly in front of the bridge with about 6-8" from the tip of the bridge.

Any guesses as to which ones are which?

No guesses, but here are my thoughts. Listening once technically and once emotionally:

I liked Mic 6 best, felt it put me "closest" to the music

Mics 2, 3, 4, 5 somewhere in the middle.

5 sounded muffled/boomy, but very good midrange resolution, could be second-best with EQ.

2, 3, and 4 hard to tell apart. I preferred either 3 or 4 depending on the listen, 4 the most detailed but also harshest. 2 least favorite by a small margin

Mic 1 least favorite, sounded cheap and muffled


I would go
6
3/5/4
1

 

[joulupukki]

No guesses, but here are my thoughts. Listening once technically and once emotionally:

I liked Mic 6 best, felt it put me "closest" to the music

Mics 2, 3, 4, 5 somewhere in the middle.

5 sounded muffled/boomy, but very good midrange resolution, could be second-best with EQ.

2, 3, and 4 hard to tell apart. I preferred either 3 or 4 depending on the listen, 4 the most detailed but also harshest. 2 least favorite by a small margin

Mic 1 least favorite, sounded cheap and muffled


I would go
6
3/5/4
1

Thanks for listening and for your guesses! I almost forgot to give the answers. They are:

1. Takstar CM-60
2. Takstar CM-63
3. My Graeme Woller KM84 build in a Takstar CM-60 body
4. Microphone Parts SDC-84
5. @jp8 KM84+
6. @jp8 KM84++

In these tests I've been surprised at how the MP SDC-84 has sounded more harsh to me than the others. There's definitely a bump in the high end which surprised me. #3, my Graeme Woller build, is almost identical to that. I feel like the @jp8 mics do a pretty good job at not being harsh on the high end, but ... I'd like to see a little more definition in the KM84++ and so if I had to choose my favorite at this point, I'd go with a KM84+.

 

[k brown]

Worth keeping in mind that per @jp8, the FET bias trimmer in the CM-63 is likely not set right; so for most fair test it should be tested for optimum setting.

 

[joulupukki]

Worth keeping in mind that per @jp8, the FET bias trimmer in the CM-63 is likely not set right; so for most fair test it should be tested for optimum setting.

I’ll have to figure out how to measure and set that on that particular mic. The other major difference on the KM84++ (in the CM-63 body) is that the venting below the capsule is significantly different than the CM-60.

 

[jp8]

Worth keeping in mind that per @jp8, the FET bias trimmer in the CM-63 is likely not set right; so for most fair test it should be tested for optimum setting.

Indeed! Though I'm not sure it would make a day and night difference at low levels (say: sub-100 dBSPL). Or even be noticeable at all. But when close miking on e.g. snares, then definitely.

The same applies to the CM-60, of which the supply voltage on the impedance converter is only 7.2V, seriously limiting headroom. @Voyager10 conveniently summarized all the CM-60/63 mods here:

https://groupdiy.com/threads/takstar-cm-60-suggested-mods-improvements.84885/post-1159287

Jan

 

[jp8]

Thanks for listening and for your guesses! I almost forgot to give the answers. They are:

1. Takstar CM-60
2. Takstar CM-63
3. My Graeme Woller KM84 build in a Takstar CM-60 body
4. Microphone Parts SDC-84
5. @jp8 KM84+
6. @jp8 KM84++

In these tests I've been surprised at how the MP SDC-84 has sounded more harsh to me than the others. There's definitely a bump in the high end which surprised me. #3, my Graeme Woller build, is almost identical to that. I feel like the @jp8 mics do a pretty good job at not being harsh on the high end, but ... I'd like to see a little more definition in the KM84++ and so if I had to choose my favorite at this point, I'd go with a KM84+.

Not to discredit my own stuff, of course, but I assume most of the tonal differences that can be heard stem from the combination of capsule + mic body back chamber/vents. And to a much lesser extent to the head amp circuits. All are essentially flat, though the amount of feedback applied around the JFET does affect the Frequency Response somewhat. The feedback capacitor is different in each of the KM84 based mics in this test.

I would have expected the GW KM84 and the KM84+ to sound quite similar, as they have the same 3U capsule, 3U transformer and same CM-60 body. The only major differences are the added RFI filter and 3G or 5G bias resistors for lower noise. But if they do sound different, then I just don't have an explanation for that. Maybe other component choices? I'm not such a believer in magically different sounding capacitors, but perhaps it does matter after all?

Think I've said it before, but I assume the audible differences in the high end between the KM84+/CM-60 and KM84++/CM-63 are most likely caused by the different back chamber and vent designs. Both circuits are flat, but the KM84++ has a bit more extended low end. And higher max SPL and lower loise, but I would not expect that to be audible in these recordings.

Anyway, I think this was another great blind test from @joulupukki ! Highly appreciated!

Btw, I'm still working on my website where I will elaborate on the KM84+ and KM84++ head amp circuits.

Jan

 

[k brown]

Not to discredit my own stuff, of course, but I assume most of the tonal differences that can be heard stem from the combination of capsule + mic body back chamber/vents. And to a much lesser extent to the head amp circuits. All are essentially flat, though the amount of feedback applied around the JFET does affect the Frequency Response somewhat. The feedback capacitor is different in each of the KM84 based mics in this test.

I would have expected the GW KM84 and the KM84+ to sound quite similar, as they have the same 3U capsule, 3U transformer and same CM-60 body. The only major differences are the added RFI filter and 3G or 5G bias resistors for lower noise. But if they do sound different, then I just don't have an explanation for that. Maybe other component choices? I'm not such a believer in magically different sounding capacitors, but perhaps it does matter after all?

Think I've said it before, but I assume the audible differences in the high end between the KM84+/CM-60 and KM84++/CM-63 are most likely caused by the different back chamber and vent designs. Both circuits are flat, but the KM84++ has a bit more extended low end. And higher max SPL and lower loise, but I would not expect that to be audible in these recordings.

Anyway, I think this was another great blind test from @joulupukki ! Highly appreciated!

Btw, I'm still working on my website where I will elaborate on the KM84+ and KM84++ head amp circuits.

Jan

And in the case of the CM-60 vs CM-63, the considerable difference in the distance between the diaphragms and the grills; the CM-60 being much more recessed gives it an unpleasant peak near the top that the much less recessed CM-63 doesn't have.

Since the two capsules are otherwise pretty much the same, the difference in polar patterns (if their published ones are even remotely accurate) must be due the different acoustic environment behind the capsules (the '63 is shown having a pattern between card and subcard).

 

[pmfalcman]

Logistically, how could I best record 6 microphones at once?

Thoughts? Here's my crazy makeshift mic clip.

PVC pipes clamps are great for improvised mic holders.
Few of these, couple of wood screws and a piece of wood.
You can fix them to a piece of wood plank on both sides (two rows) for more compact arrangement. Just make sure not to align top and bottom clamps perfectly (ca 1 cm shift) otherwise the screws will collide.
Easy to slide the mics to align diaphragms' planes and even rotate the clamps slightly.

 

[joulupukki]

PVC pipes clamps are great for improvised mic holders.
Few of these, couple of wood screws and a piece of wood.
You can fix them to a piece of wood plank on both sides (two rows) for more compact arrangement. Just make sure not to align top and bottom clamps perfectly (ca 1 cm shift) otherwise the screws will collide.
Easy to slide the mics to align diaphragms' planes and even rotate the clamps slightly.

View attachment 140762View attachment 140763

Ooo, that’s clever! What do you use to attach said assembly to a mic stand?

 

[pmfalcman]

Ooo, that’s clever! What do you use to attach said assembly to a mic stand?

I have a Manfrotto clamp (Art. 035) combined with another one, a cheap clamp intended to affix photographic lights to pipes. Just use it "upside down", sort of






You can also get a two-sided spigot, driil the wood and glue it in. Takes less space.

 

[Lemurcello]

Thanks for listening and for your guesses! I almost forgot to give the answers. They are:

1. Takstar CM-60
2. Takstar CM-63
3. My Graeme Woller KM84 build in a Takstar CM-60 body
4. Microphone Parts SDC-84
5. @jp8 KM84+
6. @jp8 KM84++

In these tests I've been surprised at how the MP SDC-84 has sounded more harsh to me than the others. There's definitely a bump in the high end which surprised me. #3, my Graeme Woller build, is almost identical to that. I feel like the @jp8 mics do a pretty good job at not being harsh on the high end, but ... I'd like to see a little more definition in the KM84++ and so if I had to choose my favorite at this point, I'd go with a KM84+.

I think that the KM84++ and Woller KM84 are the best, followed by the KM84+ and SDC-84.

My thoughts:

• Woller KM84 built in a Takstar CM-60 body: Great balance overall, leans towards being mid-heavy, and is the most linear of all.
• Microphone Parts SDC-84: Has a bit of an annoying frequency range around 500-1000 Hz with some nasal frequencies, but I also hear more pleasing air around 10-20 kHz.
• KM84+: Great balance between lows and highs, but I hear some peaks around 1-3 kHz. This mic doesn’t deliver much top-end detail compared to other mics.
  KM84++: This voicing reminds me a bit of AKG mics. I would call it modern, with clean-sounding bass and less intensive low mids. It sounds like a modern version of the KM84, but for my taste, the problem is that this mic lacks sufficient bass and/or low mid response to balance the overall brightness. I hope this can be addressed.
  
  Overall, I really like how the KM84++ is voiced, and it seems that others do too (based on survey). This mic feels light in the low mid area and has a touch of AKG sound, while still retaining the Neumann high-mid brightness. I believe this is how the KM184 is supposed to sound (or a modern KM84). I'd really like to purchase this mic, or even two, if the low-frequency deficiency is resolved. Just my two cents!
  
  I'm impressed by the work you have done! Wishing you success!

 

[jp8]

Thanks for your observations and compliments!

The low-end voicing of the KM84++ can be changed to a certain extent by changing a resistor, which tames the low-end resonant peak caused by the coupling capacitor and transformer inductance. You'll have to determine the right value based on your own preference and it may also vary from transformer to transformer. I used an ASTDS T8 transformer, but joulupukki a 3U transformer. If your preamp has a switchable input impedance, you could also change the low-end voicing to your taste by selecting a different input impedance.

I'll make the KM84+ and KM84++ PCBs available through PCBWay for a number of mic bodies. First for Takstar CM-60 and 63, then for Alctron T-02A and maybe others on request later.

Jan

 

[k brown]

I'll try this question again -

What is it people don't like about the sound of the stock CM-63?

 

[jp8]

I have started a new thread, introducing the KM84+ and KM84++, which I described on my website.

https://groupdiy.com/threads/km84-revisited.89448/

 

[k brown]

I guess I'll be the 'heretic' of this thread and suggest that the awesome sound of the KM 84 was almost entirely due to the brilliant design of the capsule and very little to do with it's electronics.

A big reason it sounded so good (especially as a Classical spot mic) was it's unusually flat off-axis response.

Would not surprise me at all if that capsule were mated with a more sophisticated circuit, that it would sound even better.

 

[jp8]

I'll be the first to admit that the sound of a microphone is mainly determined by its capsule and capsule surroundings (head basket, back chamber, vents etc). I think I've mentioned that more than once. And that is exactly why I like the 3U cardioid capsule, in combination with the right SDC body having the right back chamber and the right vents design (also mentioned by 3U Audio, btw). To my taste, it sounds balanced and in shootouts on Youtube, I could not hear a difference between the 3U and an original KM84.

You mentioned how you appreciate the flat frequency response of the KM84. Well, I think that answers your question from post #97: the CM-63 is not flat and people preferred the flat(ter) response of the 3U capsule in the blind tests.

Whether the KM84, or 3U capsule or any other capsule for that matter would sound better with other electronics? Maybe... But we should first define what is "better". Less THD? Some like a bit of "color" and use it as an artistic effect. More headroom? Some use the transformer LF compression at high SPLs to their benefit on snares. There is a place for almost any type of circuit. That's also why I designed several other circuits having more headroom, lower distortion and lower noise than the KM84. One of them being the KM84++. The other three, one with transformer and two w/o, outperform the classic Schoeps in many ways. I'll publish their specs in due time, but will not share the schematics. Whether they will also sound any better or different? I'll leave that up to my son to decide, for whom I build them.

Although some microphone properties are a matter of taste, there are, however, several properties that you typically want any microphone to have: low noise, good RFI rejection, high CMRR, good moisture protection, in most cases high headroom and high reliability. Maybe these are more important properties of head amp circuits than sound? Could be... But of course: YMMV and it is not forbidden to be a heretic in that respect.