Topic: ZOOM M2 M3 M4 MicTrak Stereo Microphones & Recorders - 32 bit one-piece devices

[Ozpeter]

Something I've noticed on samples on YouTube, and now confirmed with my M3, is that the stereo image at the rear gets inverted - speaking towards the mic from the rear left actually plays back on the rear right, etc.  But I think I read somewhere that this is a known consequence of MS mic techniques.  Maybe it's more pronounced because the centre mic is a shotgun type.  At the dead centre at the back, there's a distinct reduction in signal but that could be useful in many situations.  I've heard a shotgun-based MS recording from the rear of a hall, up in the gallery, and the stereo image and apparent closeness of the recording was beyond expectation.

[Ozpeter]

First test- a domestic recording showing spectral analysis display set to show a 140dB range to ensure nothing untoward is lurking in the noise, and later I've shown frequency response and phase.  Looks good to me.  Beware, it gets loud.  But even though I recorded a spinning washing machinie with a tumble drier on top of it close up, it still needed +12dB approx of normalisation, so Zoom have clearly configured it to only need post processing gain reduction if the incoming audio was really loud.

https://youtu.be/zNzRcAY13FE

I don't know how badly YouTube mangles the original audio, but obviously the display shown comes from the original audio flle, unprocessed apart from normalising.

[Gutbucket]

Monitoring is present as soon as you turn it on (there's no record pause button).

Zoom F8 is the same with regard to monitoring.  Effectively in rec/pause as soon as turned on, although you can pause after you start recording.  Presumably other current Zoom recorders work similarly.

Something I've noticed on samples on YouTube, and now confirmed with my M3, is that the stereo image at the rear gets inverted - speaking towards the mic from the rear left actually plays back on the rear right, etc.  But I think I read somewhere that this is a known consequence of MS mic techniques.  Maybe it's more pronounced because the centre mic is a shotgun type.  At the dead centre at the back, there's a distinct reduction in signal but that could be useful in many situations.

The rear image flip you describe is a consequence of the polar pattern of the microphones used in X/Y, and of the polar pattern of the Mid microphone in M/S in combination with the Mid/Side ratio used.  The classic example of this is Blumlein configuration crossed fig-8's, and the result is the same if set up in the classic manner as X/Y, or as M/S.  With a Blumlein stereo pair, all sound sources located behind the microphone position will be picked up with the same sensitivity as everything in front, but upon playback the positional imaging of everything in back will be flipped Right/Left in comparison to everything in front.  Substituting supercard/hypercardioids that have a less sensitive "rear-lobe" than fig-8's, the same image flipping occurs for sources in back, but they will be picked up with reduced sensitivity.  With Mid/Side using a cardioid Mid and a 50/50 M/S ratio, the decoded output will be similar to X/Y using supercardioids.  Substituting a supercardioid Mid the output will be similar to X/Y hypercardioids. 

I don't know the pickup pattern of the capsule Zoom is using in the shotgun Mid here, but I presume its a supercardioid or cardioid. Its the interference tube that defines it as being a shotgun rather than the polar pattern of the capsule behind the interference tube, but typically something supercard-ish is used as that pattern minimizes sensitivity for everything off-axis more than any other pattern and thus provides the best starting point for creating a maximally exclusive "shotgun" design.

[Ozpeter]

Wow, thanks for that tech explanation.  I have used MS mics as the basis of all my serious recordings since 1984 but I remain slightly hazy about the underlying theory!  My go-to pair for classical recording was a Sennheiser MKH 30 and 40 (if I recall the models correctly), and that rear image reversal phenomenon was never very apparent, but of course when recording classical musicians in front, and the room reverb behind, there wasn't much to reveal any such problem.  Now, with the Zoom mic that weighs a few grams and is thus easy to hand hold and speak into at odd angles, the issue is more manifest (and as you explain, the capsules used would be relevant).

It grieves me that these days I have almost no chance of recording anything, let alone a classical performance in a good acoustic, but I am hopeful that before the end of the year I will be able to get some opportunities to discover whether the M3 is a breakthrough or a disaster!  Probably somewhere in between.

[Ozpeter]

The good news is that someone has tried the M3 for recording an orchestra with violin soloist.  The bad news is that he placed the mic somewhere towards the back of the hall, and afterwards applied compression and / or limiting, eq, and heaven knows what else.  So I'm not sure it's the test I was hoping to see (and, of course, hear).  (Also the violin soloist seems to be having some issues but it looks like it was a rehearsal and maybe she wasn't warmed up, to be fair).

https://youtu.be/qLEMRTx8n5M?si=541vZs85EciiUyQ2&t=1489

Perhaps more impressive when it comes to a demonstration of dynamic range is this video where the reviewer plays his trumpet straight into it at a variety of dynamics.  This does seem to show that not only is the 32 bit float recorder section doing what it should, but also the capsules and preamps seem comfortable with the considerable dynamic range.

https://youtu.be/qanMWDrx0wM?si=nNEDelbFLlU9Xibj

Sadly my present circumstances do not allow me to get out and do my own tests, but one day that will happen (otherwise, why did I buy the mic?!)

[lsanbourne]

I'd love to see someone plug two rigid extension tube podium-style microphones (the kind with a rigid section ~25 to 50cm or so long with XLR at one end and short gooseneck with microphone at the other end) directly into the XLRs on opposite sides and mount the entire thing on a clamp or stand, eliminating mic-bar and wiring.  The mics need to be light enough that the latching XLR connection can support them, but seems reasonable to me.  May want  to use a section of coat-hanger wire to connect the two and reduce strain on the XLRs with wider spreads.

Is there a way to use a supercardioid for this purpose?

https://www.dpamicrophones.com/instrument/4099-instrument-microphone

[Colin Liston]

I recently got a MicTrak M2 stereo mic and was wondering if anyone has found a decent windscreen or dead rat for this mic.

[Ozpeter]

I repurposed one from another mic.  Sadly I still haven't given mine a test run yet.  I must stop buying stuff that I don't have time to use...

[Ozpeter]

Sorry, Colin, I misread M2 for M3.

But... I really am tempted to add the M2 to my collection of grossly underused recording devices.  Here in AU it's going for around half recommended price for the next few days, and I can't resist a bargain.  But looking through the manual of it, there seems to be much more to it than meets the eye.  There's onboard normalisation after recording if desired, and export to other bit depths onboard too.  And it can be used as a 32 bit float USB-C mic too (or 24 bit).  Much of the functionality seems based on the Zoom F3 except you don't get to choose the source - it's the inbuilt mics in stereo or mono, and that's it.  But Zoom have a serious amount of experience with small inexpensive mic capsules, and there would be no point at all in building a 32 bit float device with totally crap mics, so...  OF course it's far from a stealth device, proclaming itself to be a recording mic as loud as it can, but in my uses that's not a problem.

Watch this space...

[Gutbucket]

I'd love to see someone plug two rigid extension tube podium-style microphones (the kind with a rigid section ~25 to 50cm or so long with XLR at one end and short gooseneck with microphone at the other end) directly into the XLRs on opposite sides and mount the entire thing on a clamp or stand, eliminating mic-bar and wiring.  The mics need to be light enough that the latching XLR connection can support them, but seems reasonable to me.  May want  to use a section of coat-hanger wire to connect the two and reduce strain on the XLRs with wider spreads.

Is there a way to use a supercardioid for this purpose?

https://www.dpamicrophones.com/instrument/4099-instrument-microphone

Sure.  A coincident pair in the center, in this case the internal mics of the recorder, works very nicely between either omnis or a directional pair (or both).  Choice of which mostly depends on the room, the acoustics, how far back the recording position.   Generally a pair of omnis are best spaced wider (something 3' apart minimum is good), where as a near-spaced directional pair needn't be spaced as far (something like 2' apart is good) if angled +/- 45 degrees apart.

I mostly use DPA 4098H supercards for this in my arrays, which are choir mics intended for hanging, similar to 4099.

If using both omnis and near-spaced directionals on either side of a coincident center pair (recording 6 channels), space the directional pair 2' apart angled +/- 45 degrees and  increase the minimum spacing of the omnis to 4'. 

In either case, 5' or 6' between omnis is usually better than the minimum spacing I suggest above.

[Ozpeter]

Here is my first test of the Zoom M2 Mictrak.  It is simply a recording of the silence in my suburban garden after midnight, massively amplified by normalising.  There was some very light rain on the garden umbrella, barely audible out there at the time, but on this recording it's now really loud.  Far away you can hear the rumble of a distant motorway.  At the end there's a short recording of me speaking quietly in the same environment on a separately normalised file, to give some idea of how quiet it really was.

My elderly ears can't hear any system noise at all, despite the massive digital gain.  But maybe yours can?  Anyway, I am hugely impressed with this odd looking device - especially at half price!  Sadly, the first batch produced had a fault which caused RF breakthrough to spoil the sound, and its reputation was badly damaged.  Subsequent production runs (after that one was withdrawn and money refunded) seem fine.  Certainly I couldn't hear anything amiss.  I'll be doing a few more tests in the next couple of days, I hope, and will post the links here in due course.

https://youtu.be/Fb1r11dYpUY?si=wAutkTTvWA3TtDpM

[Edit - I just checked and the price I paid was about the typical price of a Zoom H1N.  I mean, I can't complain, can I?!]

[Ozpeter]

Today I made a very quick video which included some testing of the M2.  The supplied wind muff does help with wind noise but it really needs something more effective out of doors.  Of course for recording music indoors, that's less of a problem (apart from strong air conditioning in a hall!).  Right at the end I included a spur of the moment recording of a dog barking at me as I passed its garden gate.  It's a quite good demo of what 32 bit float is all about.

I just checked the F3 user manual and that device seems to lack some of the neat features of the M2 - perhaps the M2 is aimed at a more amateur market which needs help!  In particular, the ability to export in 24 or 16 bits, to create a normalised copy internally, and to play back at a normalised replay level (which is really, really handy).

https://youtu.be/UGMiVgoUerU

[Ozpeter]

And here's another one showing the Zoom M2 being used as a USB-C mic connected to the Pocket 3 camera.  In this mode it has some handy features such as changeable output level, mute button, replay via headphones of what has been recorded on the external device, and choice of 24 bit or 32 bit float output to the recorder.  Sadly the latter can't be recorded by the Pocket 3.  But I wonder whether the F3 accepts USB-C mics with 32 bit float output?  A 32 bit float USB-C mic at this price point has to be pretty rare.

https://youtu.be/p6I4rtF_dWc?si=m7DpAXvif0xyjJ-z

[Ozpeter]

On Christmas Day the weather forcast warns me that we will have the most severe thunderstorms for many years.  Oh great.  Well, nevermind - I will take the M2 with me to the family party and see if I can record some good 32 bit float low frequency test material while I chomp on the turkey.   

[Niels]

According to Zoom these devices should share the F series preamps, which should be good thing.

The functionality of the M4 is interesting to me as it offers both XLR and mini-jack input and perhaps even passable build-in mics(?). The missing mini-jack stereo input of the F3 makes it a no-go for me.
However, the design layout of the M4 is not my cup of tea, to say the least, but I will set up some price alerts should a lower price make this device more appealing.