Mics used for main pair are often chosen for having good off axis response to
give clarity and coherence to the stereo image.
A close mono recording mic is sometimes chosen for a particular colour, brightness or bass response.
For example the Cm3 has more of a proximity effect than the Mk21, which can be used to an advantage to create a deep resonance, while the Mk21 has a greater clarity and definition as a main stereo mic.
I like the piece, but for that purpose (heavy processing) you could record that piano with anything - any OK recording would do, even with a pair of Shure SM57s.
btw - I just got my pair of CM3s a few days ago and right now I am going to record some stereo acoustic guitar tests and do some mono comparisons with Gefell UM70 and M70 - all that through another GS hyped product - DAV BG1U. (a hype I am glad I bought into - I really like this preamp, it just simply WORKS the way I imagined it should)
These mics remind me somewhat of the Naiant company's mics, in terms of the kind of company and the manufacturing method. And the "not much bigger than an XLR connector" thing. But when I bought my Naiants some years back they were radically cheaper than these CM3's. And stupidly good at the price. Omnis though.
OK, I had a first serious recording session trying to use Line Audio mics, with a certain African musician playing balafon and I had a problem. I wanted to use CM3s in DIN stereo configuration above the balafon, but they were picking up some exaggerated sub frequency vibrations that were not heard in the room, I tried different placing, but it didn't work, so I switched for the pair of Shure KSM141, which worked without any problems or exaggerated low boom.
I attach the files - they should not be listened to as A-B comparison, since the position was a bit different and the tempo and the takes are different between CM3 and Shure examples... But the only way to get rid of this exaggerated "boom" was low cut... (example of this treatment attached).
Is something wrong with my mics or do these mics exaggerate the lows and are extra sensitive to vibrations (something that I can't work with)? I noticed certain "bassiness" or too heavy proximity effect when test recording acoustic guitars, too, but here - balafon - they were played at least 1 m away, so we can't blame that on proximity and the vibrations were not heard in the room, so it's not a credible reproduction of what we could here - which is my main judging point for mics - KSM141 represented much better what was going on in the room.
I am a bit dissapointed and after not working for this particular task, I am thinking of returning them. No other mic was exaggerating those low frequencies and I also tried KSM141 in omni and Gefell UM70 in cardioid and omni and there was no exaggerated boom...
Did you use the shockmounts? LF can sometimes travel very well through floors and mic stands. The CM3 has unusually flat response, down to the very bottom of the frequency range, and indeed have strong, but unusual proximity effect. They don't have a built in low cut has other mics have so you might, for some close mic'ing applications (about 4 feet or less) need to taylor the low end a bit.
Also, check the KSM141 and the UM70 cardioid response curves, you'll see a very noticeable low end drop. So to get that type of LF response, a bit of low cut is indeed going to be required when using a CM3, which is much more linear. Different mics for different applications!
Ok, I tested them again yesterday in a session. Unfortunately I didn't have time to do more, but I managed to set up a comparison of spaced pair of KSM141 in omni and CM3 in the same position above the balafon on the same take with the same preamps - some average (but very OK) preamps in Yamaha AW1600 recorder.
I like the tone of CM3, but they do exaggerate the extended low bass vibrations - the chart for KSM141 in omni extend well down below very linear, too, but there is none of that rumble to be heard. But that's nothing a low cut of some 18dB at around 85Hz couldn't solve, though. Still I am curious why is that? I don't buy into the argument that they go down in a more linear way than other mics - for example here's the omni frequency response of KSM141 (the second chart)
There's even a visible sub bass lift and still no rumble heard in omni setting.
Anyway - I like the tone of CM3 and I would use them instead of KSM141 on balafon, but since I was afraid to screw the session with the mic I don't know well enough, yet, I couldn't use them this time. Solving the problem with low cut didn't seem right to me, since there was no problem with other mics... I was afraid something is wrong with the mic.
I'll keep them, because for the price they are good. But I have a clearer picture of what they are now. They are a 230EUR (per pair) mic with a nice tone, but not "killer of Schoeps" or anything of that sort. Also if a friend would ask me what to take (as the only mic pair) on a recording field trip to Guinea I wouldn't recommend that mic, since it doesn't seem to be so reliable in ALL the situations... Something like a KSM141 seems to be more of a reliable workhorse. Or maybe a pair of RODE NT55. But they are almost twice the price of CM3. And I expect a pair of Schoeps MK21 would deliver that wide cardioid "mojo" and the tone comparable to CM3 (or maybe a bit clearer?) with no compromises and a feeling of reliability and "no fuss".
So for now, I'll stick to them. I think it is more that I like the characteristics of wide cardioid - a blend of cardioid focus and more natural picture of omni. So, my wet dream is not solved. Still have to save for a pair of Schoeps MK21... (so - for masturbatory purposes - if anyone can post more direct comparisons between Schoeps MK21 and Line Audio CM3 in different settings and on different instruments would be welcome).
Maybe those shock mounts are useless, but KSM141 in the same situation were on a regular mic holder and still no such strong vibrations picked up... now it can be debated whether this is a quality of CM3 or its deficit...
It is true that the situation was very specific - heavy hitting musician - and the balafon is played with rather large semi hard beaters: http://www.bristoldrumming.com/cart/...raditional.gif ,
which all transmits quite some strong vibrations - but the thing is - only CM3 did exaggerate those in a recording. I could get rid of it with low cut and no damage to the overall sound, but it surprised me. It can't be proximity, since the mics were quite high above the balafon.
It seems in your case it they capture too much low end (but this is why we have high pass filters I guess!)
It's what actually struck me in a positive way when I first heard them BUT it might mean they need a bit of care when setting up for certain situations. For me, it's really a nice problem to have.
Experimenting with a CM3, I noticed that if the housing is removed,
it loses much of the bass response. It also causes the mic to sound
less focused and detailed. I was impressed by the degree to which
the housing creates the sound of the mic (at least on close sources).
Hi again, I'd like to add that 1) each CM3 is built and critically measured and tested before leaving the Line Audio plant and 2) I test again everything I ship. So in The Listener's case, I'm sure it's not a deffective mic (or pair of mics); yes, the CM3 is very different from most SDC's and this is what makes it appealing to most... and indeed, it's a great mic for the price. I would be very interested in hearing another MK21 versus CM3 test, but the ones I heard seem to indicate that the CM3 is definitely extremely close in performance - yet not in price. Would I use a Schoeps MK21 instead of a Line Audio CM3 on a given situation, most likely yes (although the small size of the CM3 is still a strong point), but can I afford a pair of those Schoeps, no! I do believe that the CM3 is a great addition to any mic collection as it gives a totally different response than most pencil mics can offer, with the exception of the equivalent Schoeps combo, which few studios have or could afford. A very useful mic at a very attractive price, hand built in Sweden... is it the perfect mics for every application, no, but when you need ruler flat response with extended LF response (yes, as we now know it this can be an issue in some situations) they're hard to beat.
Hi, what we all can hear recorded with your CM3's without low cut is, in my opinion, typical for that kind of instruments sort of rumbling. That happens with most of vibraphones, marimbas, ksylophones etc. One may not hear that recording more melodic (lines like) kind of playing but it usually appears with that kind of african playing - it's a melody but repeted and very dense so we have that chord sort of sound too. I work a lot with vibraphonist and other mallet players and some effects are extremely more brutal and sound like mic would just explode in a while. If you put your ear to the instrument (i do not recommend that for long time though) you'll feel your ear can't stand that for any longer and that doesn't mean you should send it back to manufacturer. These mallet instruments are not well tempered (like piano) instruments and are never "perfect" (which makes them so perfect at the same time). Even the most expensive model of Yamaha vibraphone where 3 overtones of each bar are tuned is not perfectly tuned instrument and some chords doesn't sound perfect (read: from the scientific point of view). Especially african, hand made balafone, one of a kind, tuned by someone's ear probably using knife.
I find your CM3 with no low cut recording the very best as i can hear the real resonance produced by a great imperfect/perfect instrument. The shure mic doesn't go low enough to transport it. If you don't like how it sounds - OK, eq it!, just doesn't seam like a mic problem to me at all.
Though i would never compare microphone to human's ear (as i think mics are made not to copy ears but rather as a part of a recording system chain which works together, where all parts are important) i highly belive in checking the mic position with your ear first ,together with kind of studying the real sound of the instrument. (not trying to be nasty, that's just my approach). best wishes.