Topic: My AT2022 is fine, till I plug it in my MT2...

[Breeze]

I finally got my AT2022 (unbalanced stereo) and it's perfectly adequate for my needs; not a stereo condenser but a good bang for the buck. But when I plugged it into my Microtrack II's 1/8" I noticed the Left channel was 18 dB down from the Right. Now I've covered the details extensively in other forums with no ideas proffered about what could cause this, so I don't want to make a long story of it here. In brief, the mic works properly in every other recording device, preamp and mixer I could find except the MT2 so barring some strange unforeseen interaction between the AT2022 and the MT2, the evidence points to the MT2 as the culprit. Since I mostly use it as a bit bucket for my Mini-Me, I'm not too concerned, but I'd still like to occasionally use the AT2022 direct into the MT2 1/8".

In my tests I found that if I introduced DC blocking caps between the mic and the MT2, the problem didn't present. So I figure if I make a cable with bypass caps built in I can at least use it that way. Now of course this is likely going to shave some low end off the mic and degrade the signal somewhat; and then there's the question of polarity. Would it make sense to use a non-polarized electrolytic here of say 47 uF in size? In fact if I made the voltage > 50v, I could also protect this mic from accidental exposure to phantom power (since I use a custom made XLRF to 2*XLRM cable as well).

So in the end <phew!>, can anyone recommend a cap type, voltage, and value that would make sense in this context? Thanks.
   

[SmokinJoe]

First, make sure the MT2 isn't putting out plug-in-power.  If it was, that might throw a wrench in the machine, I don't know.

Secondly, I've seen a few schematics where people use 10uF, so I think that's enough, and 47uF should be more than enough.

[Breeze]

Thanks SmokinJoe. I don't think there's any way of turning off the bias power on the MT2's 1/8" stereo mic input (4.5v BTW), only the phantom on the 1/4" TRS. But I did try the mic on an LS-5 with the bias voltage ON: the levels were in spec and it sounded just fine, so...

[F.O.Bean]

I'm excited to hear this thang

[Breeze]

I'm excited to hear this thang

I'm not a concert taper, but I'll see what I can do

[Breeze]

Secondly, I've seen a few schematics where people use 10uF...

Wish I could get a schematic for the MT2, but that's a no-go. Anyone know what caps are used as a DC block on the MT2 1/8" stereo in and on the 1/4" TRS's?

[carpa]

@breeze:  as I'm interested in this new stereo microphone for my Edirol R09hr or future device like the new Olympus ls20m videorecorder, I'd like to have your impression regarding sound quality, noise ecc....I'd use the mike for classical piano and chamber music  concerts.
I already own a littlebox plus two little omnis from Naiant, but I'd use a stereo mic coupled with littlebox ( minijack input) in case cards are preferred or directly into the recorder for a fast recording.

I've also read that such a mike could be used as a side mike for a figure 8 set, adding another mono mike; how can it be done  with a littlebox (I have both balanced xlr inputs and a stereo minijack unbalanced input).

Excuse me for posing too many questions...thanks a lot for any answer.

[Breeze]

@ Carpa: as I''ve mentioned, my recording interests are not so much in concert recording, but more in ambiance and sound effects (on a budget). I've been busy troubleshooting the above problem since I got the mic a week ago, but I plan on getting some recordings done ASAP and I'll post something here soon.

I find the noise floor definitely lower than the older AT822 this mic replaced. I've been concentrating on levels so I need to record more to make a proper assessment. But my initial impression is that it's a fairly neutral sounding mic but not a warm one. As for using it as a side mic for MS, I just tried it and it doesn't work that well. The mono signal recorded plugging into a single balanced input ends up with practically no low end, which shouldn't happen with a proper figure 8; it sounds much better when both channels are mixed to mono at the console and with the capsules in their rest position they point directly right and left, so that might work better. TBC...

[carpa]

thanks a lot. When you say that this mic doesn't seem to have a warm sound, you mean something concerning a bright performance on the upper end or you find it lacks low end? I ask this because the frequency plot shows some 6 db per octave roll-off starting from 150 hz down...
thanks again

[Breeze]

After quickly recording some tracks off my sound system last night, my initial enthusiasm for this mic is veering towards disappointment. I've been spending too much time troubleshooting the chain and not enough actually listening to the mic. Yes the low end is anemic as it tapers off a good 10 dB at its lowest and the high end is somewhat shrill and uneven: I definitely have to re-eq the resulting material so it sounds more natural but getting it to sound like the source is a chore, and likely impossible.

But besides that and more of a concern to me is the lack of clarity in the imaging. The subtlety of the mixes get lost; slapbacks and other mix details are hard to distinguish. I think there's too much variation between the capsules (specs say 3dB at 1k which is a lot and it could be worse at other Fqs). This is definitely a cheaper mic. In fact, it doesn't sound a whole lot better than some of the home-made mic's I've made in the past. It's a marginal step up.

I'm going to try some more tests and I'll use it in the field and see what it sounds like there. As for the MS thing: I used Voxengo's MSED to separate mid and side off commercial tracks and the side track usually does sound thin and lifeless. Sorry, I don't have a lot of experience with MS so it's possible that the AT2022 can be used as a side mic but I don't know how well it can perform that function.

TBC...

[Nick's Picks]

hmmm
I would think this mic is cool...and versatile w/the moving caps.
but I'm surprised to hear your disappointment in its "focus"...

isn't the mic itself powered by battery ?
if so, then wouldn't you just run "line in" w/o plug in power ..., maybe a converter to make it 2x1/4" mono jacks for the top ?

[Breeze]

hmmm
I would think this mic is cool...and versatile w/the moving caps.
but I'm surprised to hear your disappointment in its "focus"...

isn't the mic itself powered by battery ?
if so, then wouldn't you just run "line in" w/o plug in power ..., maybe a converter to make it 2x1/4" mono jacks for the top ?

Yes I expected more out of this mic too. Mind you, I haven't ruled it out completely because recording pre-recorded material in a smaller room will have consequences on the pickup of the microphone since it's much more susceptible to room modes and reflections than a concert venue or an open air environment. I placed the mic at the equilateral juncture of the speaker spread and my room does have some acoustic treatment overhead and on the front wall behind the speakers. 

I'm not not sure I understand what you mean about phantom power: yes it's powered by an AA battery and my problem with the MT2 seems to be a problem with the MT2 (!). I did the above tests with an FMR RNP through an RME ADI-8 converter and I use a custom cable that runs the unbalanced XLRF to 2 XLRM (pin 3 GND to 1 & 3 at the XLRMs). I'm going to run some more tests tomorrow through my Mini-Me to rule out the signal chain and see if it's any better. And I may have time this weekend to to some outdoor recordings.

Stay tuned... 

[Nick's Picks]

ok..., living room tests aside...


the mic is powered.  It sends a line or mic level signal.  no phantom, no 5v PiP necessary.   right ?
if so (as I understand the mic), then it should just be run "mic in" w/no Plug in power.   or, you could run it "line in".
I'm just verifying that you are not sending the mic any voltage.

[kirk97132]

there is only a MT-1 manual in the TS archive, BUT, that manual states that the 1/8" mic in jack has 5v PIP power, it does not offer any way to disable it or bypass it.

[Breeze]

there is only a MT-1 manual in the TS archive, BUT, that manual states that the 1/8" mic in jack has 5v PIP power, it does not offer any way to disable it or bypass it.

That's true for the MT2 as well. But AT also states that this mic can handle a bias voltage without issue (which is typically under 5 volts), but not phantom power (typically 48 volts). The MT2 is rather high at 4.5 volts; maybe there's an out of spec part in the AT2022 that can't handle it? ASAP, I'll to a test providing DC bias voltage from a variable voltage source to see if the left channel breaks down before it hits 5 volts. Maybe that's the problem. I never got to measure the voltage on an LS-5 where this mic worked fine with the bias voltage enabled (can't seem to find that spec anywhere). Maybe it was lower...