[Richard Crowley]

Probably a very large percentage of 3.5mm TRS connections are un-balanced stereo. Mic-level, line-level, or headphones/earbuds, etc. 3.5m is a common and popular consumer connection style.

Virtually 99.999% of XLR connections are balanced monaural. Whether mic-level or line-level.
XLR is a professional (and prosumer) connection style.

It is not clear what the microphone on the camera is for?
Or why you think you need an external recorder for it?
Why not simply plug the on-camera mic into the camera and record in-camera?

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Recording audio without metering and monitoring is exactly like framing and focusing without looking at the viewfinder.

[Richard Crowley]

[Eric Toline] “The bad news is they are discontinued by JBL.”

But the good news is that vendors are clearing out the first-generation “LSR” series. I got my LSR308 monitors for $150 each which is the bargain of the year. Shop around.

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Recording audio without metering and monitoring is exactly like framing and focusing without looking at the viewfinder.

[Richard Crowley]

There are certainly high-end, near-field monitors like Genelec which are a sure bet. But at a significant price.

IMHO, the best value for excellent performance at a great price these days is the JBL 3 series (305P, 306P, 308P). I have a pair of 305 and just got a pair of 308

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Recording audio without metering and monitoring is exactly like framing and focusing without looking at the viewfinder.

[Richard Crowley]

Also check out https://incompetech.com/music/royalty-free/

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Recording audio without metering and monitoring is exactly like framing and focusing without looking at the viewfinder.

[Richard Crowley]

Does “short interview” mean on-camera interviewer grabbing subjects and positioning them in front of a stationary camera? Is the interviewer on-camera? Or does it mean a mobile (shoulder-mount) camera roving around looking for subjects?

The first scenario typically uses a hand-held mic which the interviewer alternates between their mouth and the subject’s mouth. Or the interviewer has a separate headset mic for themselves and uses the hand-held exclusively on the subject. The interviewer is responsible for getting and keeping the microphone close to the subject’s mouth, especially in a high-noise environment. It would be helpful to have the interviewer wearing good isolation headphones so they can ONLY hear the program audio. That helps the interviewer/reporter HEAR what they are doing.

As has already been mentioned the most popular mic for this in North America is the ElectroVoice RE50. The ElectroVoice RE50 is just an EV 635a microphone inside a larger shell for added mechanical isolation (to reduce handling noise) and additional breath/pop/wind filtering An EV 635a mic could be a viable alternative but without the extra mechanical isolation and pop-filter of the RE50. You can put an external foam pop-filter over the 635a.

In Europe, the Sennheiser MD42 seems to be the go-to microphone for hand-held reportage. And a newcomer is the Rode “Reporter”. These are all dynamic microphones with deliberately less sensitivity (compared to condenser mics) to provide better separation (signal-to-noise ratio) between the desired signal (the subject’s speech) and the surrounding noise.

OTOH, if “short interview” means “run-n-gun” mobile camera operator chasing down subjects and asking questions themselves, perhaps one of the few legitimate use-cases for a camera-mounted microphone like a short shotgun, etc.

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Recording audio without metering and monitoring is exactly like framing and focusing without looking at the viewfinder.

[Richard Crowley]

We can’t really get any farther without knowing exactly what you mean by “noise”. Can you post a sample clip somewhere where we can hear it? We need to hear the normal audio along with the noise so that we can hear the proper dynamic reference.

The output of the mixer is “for” whatever you want to use it for. SOME people use mixers like that for “powered or amplified speakers”, but many others have never used them like that. It really makes no difference at all.

You can try it, but plugging the camera power into utility mains power won’t reduce this “noise”, and quite possibly can make it worse. But only YOU can do the experiment with YOUR gear.

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Recording audio without metering and monitoring is exactly like framing and focusing without looking at the viewfinder.

[Richard Crowley]

You can see the manual online at the URL below.
On page 7 is a description of the red button (power and “check”), and what the various LED colors mean.

It appears that the red button turns the receiver on/off, and is also used to check the battery state.
Your reported symptoms would seem to indicate that you are not turning the unit off,
And the red LED means that the battery needs recharging.

Ref: https://en-us.sennheiser.com/global-downloads/file/9816/AVX_Manual_06_2015_EN.pdf

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Recording audio without metering and monitoring is exactly like framing and focusing without looking at the viewfinder.

[Richard Crowley]

What exactly does “noisy feed” mean here? There are a dozen different kinds of “noise” and the diagnosis can be quite different for different kinds of noise.

Do you hear noise in the mixer (as from the headphone output) separately (before you connect the camera)? Effective audio path troubleshooting and diagnosis attacks the problem step-by-step. One microphone at a time, etc.

There is nothing about the Mackie 1203 VLZ3 that makes it any more (or less) “optimal” for music recording vs. using it with a camera. You should be able to connect the XLR outputs from the Mackie mixer into the Canon camera XLR inputs at either mic-level or line level. Of course you must match the levels at each end. If you use the line-level inputs to the camera, then you must set the mixer ouputs to line-level. And same for mic-level. (set for mic-level at each end).

The Sennheiser wireless receivers should not care whether the phantom power is turned on or not. We don’t know what “3 hard-wired mics” you are talking about? Presumable one or more are condenser mics if you are asking about phantom power.

Do you have the same “noise” when the camera is operating from battery power and not connected to mains power? Ground-loop (or other grounding problem) is one source of some types of “noise”. But without better details of exactly how things are connected and other details, we really can’t offer any more specific suggestions.

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Recording audio without metering and monitoring is exactly like framing and focusing without looking at the viewfinder.

[Richard Crowley]

[Mark Suszko] “Well, a parabolic might,”
Highly doubtful.

You are asking for discrimination between a vocal and a rather loud instrument with many overtones just inches away from the singer’s mouth. And the instrument and the vocal are in the same general band of frequencies. What you are asking for just is not possible with the technology that we currently know about.

Besides, parabolic reflectors severely limit the low-frequency response (unless you have an enormous dish) which is fine for listening to quarterbacks call plays, but will sound like someone is playing an instrument through the telephone.

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Recording audio without metering and monitoring is exactly like framing and focusing without looking at the viewfinder.

[Richard Crowley]

No microphone at 10x your budget will do what you are asking. You cannot achieve that kind of directionality from even 3 feet.

Put an ordinary microphone on an ordinary stand in front of the performer’s mouth for the vocal. If you use an ordinary directional (“cardioid”) microphone you will get the kind of vocal/instrument isolation you seek.

There are many choices for a directional vocal mic, a mic stand, and an XLR to phone (IOS/Android) adapter that will fit within your $100 budget.

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Recording audio without metering and monitoring is exactly like framing and focusing without looking at the viewfinder.