Low audio levels ATEM TVS through audio to SDI mini converte

When I connect one mike to a camera (HDMI), I have good audio levels in the ATEM TVS. But when I connect the mike to the sound board (Behringer: XENYX 1204USB) through a BlackMagic Analog to SDI mini converter, the levels are too low. The gain is all the way up already. If I raise the volume any further, I have a horrible buzzing background noise. Any suggestions on what I might be missing?

Digital audio levels are much lower than analog levels for headroom purposes.

+4 dBu = 0VU = −20 dBFS

The professional analog audio standard of +4dBu will measure 0VU on an analog audio console.
The digital audio standard of -20dBFS will measure around -20VU one the same console.
A typical audio console has a mic input gain of about +60db.
A typical microphone needs 30-40dB of gain to get a 0VU level. When converted to digital is loses 20dB of gain.

Bottom line: The console doesn't have anything left or "no headroom".

Hope this helps!
D

Professional "Line level" is +4dBu. Consumer "Line level" is unbalanced -10dBu (those red and white phono plugs). Microphones use "mic level" at somewhere around -30 to -60 dBu. It is a much lower signal level. The camera has a microphone preamp to boost the low mic level. The SDI miniconverter does not have this preamp, and expect a line level input. It is incapable of properly dealing with mic level audio.

Your options are:
You can go through the camera and use it's preamp.
You can go straight to the audio board - bypassing the miniconverter, and use a mic preamp in the board.
Or, you can add an external mic preamp before the miniconverter to boost the level.

Thank you for your answers. I understand the situation a little bit better now.

For my situation (school tv studio) I'd really like to use the soundboard if possible. The Behringer: XENYX 1204USB does have mic preamp so I am thinking maybe I did not connected it correctly to the miniconverter?

I use the RCA output.

This is analog sound going to the ATEM TVS, is there a way for me to bypass the converter as you suggest?

Would something like this work better than the mini converter?
Gefen GTV-AAUD-2-DIGAUD GefenTV Analog to Digital Audio Adapter from B & H

Thank you for your help!

Using RCA is the problem. RCA is an unbalanced connection meant for consumer quality equipment and is up to 14db less than your balanced 1/4" TRS outputs. The mini converter is expecting a balanced connection on a 1/4" TRS cable.

Your first post sounded like you went from microphone to SDI converter to audio board. If you are going mic -> audio board -> Sdi converter, it should work, but with the RCA connections, it would be about 14 dB low. Use 1/4" TRS connections at the converter, and either 1/4" TRS or XLR at the board.

Alright, so I tried the 1/4" at the converter and the XLR at the board and did not see any improvement.

However, I tried a different microphone and now it works!!!

I was using an inexpensive wireless handheld microphone. And while that one works well on the camcorder, it does not work so well with the sound board.

I now use a Shure SM58 microphone, wired with XLR connector and it works great.

Thank you for your help!!!

Digital audio levels are much lower than analog levels for headroom purposes.

+4 dBu = 0VU = −20 dBFS

The professional analog audio standard of +4dBu will measure 0VU on an analog audio console.
The digital audio standard of -20dBFS will measure around -20VU one the same console.

I know this is a way old post, however, this comment is in error. As I found it when I was searching for what the ATEM audio output was referenced to, I want to correct it for anyone else who might come across it in a forum search:

+4dBU and-20dBFS are exactly the same, there is no difference in level or distance to clipping (headroom).

This statement is correct:
"+4 dBu = 0VU = −20 dBFS"

However, these statements are not, and directly contradict the above true statement:
"Digital audio levels are much lower than analog levels for headroom purposes."
"The digital audio standard of -20dBFS will measure around -20VU one the same console"

Lemme 'splain...no, there is too much, lemme sum up (points for reference <g>).

An analog meter reading of 0VU references +4dBu, or 1.228 volts.
A digital meter reading of -20dBFS also references +4dBu, or 1.228 volts.

Max audio level on an analog meter reads +20VU and references +24dBu, or 12.28 volts.
Max audio level on a digital meter reads 0dBFS and also reference +24dBu, or 12.28 volts.
Both of these meters give 20dB of headroom to the point where clipping would occur.
Both of these meters read in dB increments...one is just dB above or below 0VU and the other is dB below full scale, but both result in the exact same voltage output levels from the mixer.

So, feeding a 0VU analog signal into an analog console will read 0VU.
Similarly, feeding a -20dBFS digital signal into an analog console will also read 0VU, not -20VU.
Feeding a 0VU analog signal into a digital console will read -20dBFS.
Similarly, feeding a -20dBFS digital signal into a digital console will also read -20dBFS.

Hope this helps,
Jeff

Spot on Jeff. Lots of confusion on this topic with new shooters especially.
Cheers

Well, it is not so simple
There is no real standard between 0VU and analog output(s) levels. Yes, usually it's +4dBu. But not allways. Levels can also be 0dBu, -2dBu etc, it depends from hardware (for example- servo balanced vs impedance- balanced etc). There is broadcast hardware with much higher line levels (like +14 dBu or something).

Also, consumer digital audio uses wrong levels (without normal headroom) and have usually +12dB (or similar) offset to "normal" reference zero, so gain structure can be totally wrong, if you dont use trim.

There is also -18dBFS = 0VU = +4dBu standard (mostly professional audio "thing"). Many prosumer and consumer devices uses something like -12dBFS or -6dBFS as reference zero (e.g. 0VU).

And one more topic- how clipping is handled (hard vs soft clip, clipping level etc). This can be very tricky sometimes, especially in PA work, because analog consoles have too much headroom for amps so using limiters is crucial.

[Gary Adams]

Hello All. One thing worth mentioning. Most of our line level (+4 in our case) analog circuits have a 10 dB headroom while the digital circuits have 20 dB. So the analog portion of the ATEM will clip at +14. Usually it's the high frequencies in digital that go higher but if you are using analog with digital you need to be careful of the levels.

Regards, Gary

Well, it is not so simple

Ah, very true. I should have thrown "typically" in there, which +4dBu and -10dBv usually are considered, however, your point is spot on that we must always check the equipment specs when interfacing them. My max +24dBu example is also only typical: depending on the mixer, it could also "commonly" be +18, +20 or +22.

I did find in my experimentation that if I send a -14dBFS 1kHz tone from my mixer (+4dBu@0dBFS) to the ATEM's XLR inputs, the level reads -20dBFS on the ATEM EXT input and Master output with both faders set to 0dB (edit: I initially wrote 0dBFS, but the fader settings go to +6dB), so there is a 6dB loss internal to the ATEM (analog/digital conversion). However, although I've not tested it yet, rumor has it that the XLR outputs don't exhibit that loss. Anyone seen that themselves?

Thanks,
Jeff



Sent from my iPad using Tapatalk

This is my experience-
viewtopic.php?f=4&t=65308

What is it (software bug maybe?) I do not know, but this is not unity gain for sure.

At least ATEM's inputs seems to have soft clip, right?

This is my experience-
viewtopic.php?f=4&t=65308
What is it (software bug maybe?) I do not know, but this is not unity gain for sure.
At least ATEM's inputs seems to have soft clip, right?

Wow, yeah, I'm not getting any clipping at all like that, but I don't think I'm hitting it that hard. This is what I'm trying to avoid with upping my audio level into the ATEM. We come in from the audio mixer on XLR and the ATEM (old HD version) outputs feed destinations as follows:

• HDMI Program to Live Stream via Teradek Vidiu (used to be SDI to PC running vMix via Decklink card)
• HD/SDI Aux to lobby TV with SDI/HDMI mini-converter at TV
• Composite NTSC SD output to NTSC CATV converter for backstage and green room distribution

We use the XLR outputs to provide audio for the CATV feed fed by the Composite NTSC SD output, which is XLR/TRS cable to Rolls HE-18 for transformer isolation and balanced to unbalanced conversion.

None of this clips for us, but we're only running around -18 to -12dBFS on our mixer, which apparently ends up being -24 to -18dBFS on the ATEM meters based on the 6dB loss we're seeing. So, this is what started me on this audio level research, trying to figure out what the audio in/out specs were for the ATEM and Teradek Vidiu were and how to make sure we avoid clipping.

I'll be working on pushing levels up for this weekend's service so I'll see if there is any clipping and report back.

Thanks,
Jeff