[Richard Crowley]

Thanks, Ty.

Sometimes I wonder if I should answer the “too-arcane” questions that aren’t really production-related. Maybe I should suggest other, more appropriate forums like GearSlutz for more audio hardware-related, and EEVblog for more general electronic-related questions?

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

[Richard Crowley]

It is easy to convert speaker-level (including 70v down to line-level to feed into the B amplifier. The car audio people do it all the time. They have little attenuator gadgets available for really cheap.

To switch the 70v speaker line, you just need some sort of DPDT switch. There are dozens of different styles of switches, and thousands of choices. Nothing magic here. Be sure to switch BOTH wires of the 70V ine.

Note also that it is not good form to leave a power amplifier with no load attached. Another reason to switch (or mix) at line level rather than messing with the speaker lines.

I would still recommend to avoid switching speaker level circuits if at all possible. And it seems easy to avoid it.

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

[Richard Crowley]

Not clear if you are asking about switching the 70V distribution lines, or the inputs to the 70V amplifiers? Is there some reason why you can’t switch the input to amplifier B?

The potential issue with switching the “B” 70V string over to the “A” amplifier is potential overload. You must establish how much load is on the “B string”, and how much load is on the “A string” in order to determine whether you have enough reserve capacity in the “A” amplifier to handle BOTH strings.

Switching (or simply summing) the “A” program into the “B” amplifier would be a much safer alternative.

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

[Richard Crowley]

Can we assume that you mean a Sennheiser EK 100 G3 receiver? Can we assume that you mean the “AF OUT” line-level 3.5mm output? There is no headphone jack that I can see?

Most cases of hiss have nothing to do with grounding. And that would appear to be the case here, at least judging by your reported symptoms. Since all parts of the system are battery-operated, there is no ground reference anywhere. And the system does not need any kind of ground to operate properly.

Excellent troubleshooting technique to evaluate each link in the audio chain separately.

Did you hear ANY difference in noise floor on all the various sensitivity settings on the transmitter?
And when you changed the audio level settings on the receiver?
I would have expected obvious changes in the noise floor when you adjust the audio levels.
And you confirmed that it is NOT in squelch (muted)?

Did you try different cables, especially between the mic and the phantom supply, and between the supply and the transmitter?
I didn’t see any mention of what you used to connect your XLR output (from the power supply or the MD46 mic) to the transmitter?

It is also not clear from your description whether the problem is that the audio signal level is too LOW, or whether the noise floor is too HIGH. They both produce the same resulting poor signal-to-noise ratio. But the causes (and solutions) are rather different.

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

[Richard Crowley]

Can I connect my XLR wireless receiver output to a venue sound system?
Assuming that the venue has a standard XLR microphone input, then yes, you can connect the output from your receiver into the venue system just as you would plug it into your camera.

How do I connect the output from the venue sound system to my camera?
That is not quite so straightforward as your first question. Because most modern sound systems use standard XLR microphone inputs exactly like your camera. However, there is no standard across ALL venue systems for extra outputs for visiting videographers.

Many venue systems have no extra outputs at all. Many older, more traditional places like older hotel banquet rooms or meeting rooms or ballrooms have only built-in systems with no extra outputs. Although higher-end systems may have something like a “Press Feed” which would be a mic-level or line-level output available to visitors (like you).

If the event is using a portable system, it likely has some sort of mixer which will very possibly have outputs that could be tapped into for sending to your camera. But depending on the gear they are using, and the configuration (how many outputs they have already occupied, etc.) you never really know what audio level or what kind of connector you must interface with.

Many event videographers have an audio interconnect kit. Mine is based on a very modestly priced isolation transformer, the Rolls DB25 “Matchbox” direct-box. That little box is an excellent multi-purpose tool for not only adapting various connectors, but also adapting various levels (from mic-level to line-level to speaker-level) and converting it into balanced mic-level to send to your camera mic input (just as you do with your wireless receiver).

Not only that, but an iso-transformer like that also performs the very critical function of isolating your camera from the venue system to prevent ground loops and hum. An isolation transformer protects both you AND the venue system from ground-loop-caused hum and other kinds of interference and noise. The output from the Rolls DB25 is a male XLR connector with a microphone-level signal that should plug right into your camera (through an ordinary XLR mic cable).

The Rolls DB25 “Matchbox” also features a built-in “volume control” that allows you to adjust for a wide variety of audio signal levels coming from the venue system. So that you can optimize the signal going to your camera.

Along with the “Matchbox” you will need a few interconnect cables for various sources like XLR (typically male XLR for an output, so you need a cable with a female XLR), or 1/4 inch TS or TRS “phone plug”, and maybe also RCA and 3.5mm (like for headphones or earbuds) also.

However, that scenario requires a “hard wire” between the venue sound mixer and your camera. In some cases, you are close enough to the venue mixer, or can safely run mic cable between the venue system and your camera.

It sounds like they are recommending that you use a SECOND wireless “hop” between the output of the venue sound system and your camera. You can get cables for the transmitter that allow it to be plugged into one of the outputs from the venue sound system (much as described above).

Do you have two wireless systems? If not, you will need to either use an XLR mic cable, or rent (or buy?) another wireless system.

In any case, it is very advantageous to contact the operator of the venue sound system (whether in-house or outside contractor) to arrange for a house-mix feed for your camera. You can work out details like what kind of feed they have, what kind of connector, what signal level (mic-level or line-level).

Sorry for writing such a long epistle, but always good to be well-prepared and equipped.

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

[Richard Crowley]

How much is “a tad”? If it is only one frame plus or minus, then you are done. Your photo cut off the scale of the timeline so we don’t know what we are looking at?

These are audio-only tracks? What about the audio from the video track(s)? You were able to sync one(?) of those tracks with the video? Your question seems rather confusing without the whole picture of what is what.

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

[Richard Crowley]

Yes, you need specifically a “stereo-breakout” style of Y-adapter cable. The traditional kinds of Y cables will not properly break out the left and right channels separately. If it doesn’t say specifically “stereo-breakout” don’t buy it.

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

[Richard Crowley]

It might be an interesting experiment. You might want to buy from someplace that will let you return one of them if the back-to-back scheme doesn’t work.

There may be three issues with doing this:

[Richard Crowley]

Remember that the microphones in DSLRs are little 73-cent omnidirectional capsules buried inside the body behind a pinhole. Even worse than the kinds of microphones built into “proper” video camcorders. In fact the same “technology” (or lack thereof) as you find in a cell phone (which is expected to be used a few mm from your mouth.) That is why you see a variety of small, lightweight microphone products that mount in the camera shoe of your DSLR. Particularly the line of range of on-camera mics from Rode.

Note also that most hyper-cardioid and “shotgun” microphones actually have a small lobe directly to the back of the mic. And some people exploit that lobe to capture camera operator speech. It might be worth trying as the rear lobe is much less sensitive than the forward lobe and that somewhat equalizes the dramatic distance difference. But you would be much better off if you recorded the camera operator mic on a SEPARATE channel from the primary mic.

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

[Richard Crowley]

I don’t know what is “the way to go” for your particular situation. Only you can answer that question for yourself. but I am saying that a forward-pointing shotgun (or hyper-cardioid) of some kind in one channel, and a lav (or headset) mic for the camera operator is a popular solution for many people. Remember that you should ALWAYS monitor (and meter) your audio while you are recording. A solution may be a pair of good headphones with a boom mic attached. There are a growing variety of these available at popular prices, made popular by the gaming crowd.

Figure-8 microphones exist, but they are note really suitable for your application. For one thing they are rather fragile, made mostly for controlled conditions in a recording studio. Expensive and not likely to survive well in a “run-n-gun” field situation. And for another, you get exactly the same pickup pattern and sensitivity forward and backward. That is almost certainly NOT what you want for a camera operator inches away from the “back” of the microphone, and a subject perhaps several feet away from the “front” of the microphone. You are practically guaranteed significantly different sound levels, and with a figure-8 microphone you are stuck with a 50/50 mix of “front” and “back”. AND you are stuck with BOTH front and back recorded on the same channel. A terrible situation for mixing in post-production.
And even worse if you need to use the video live or with no editing. Not suitable on several levels.

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