Audio troubleshooting - webcast

We held our first successful broadcast of a sacrament meeting yesterday using the webcast system.

The only problem we had was a low buzzing, or droning noise on the audio. It wasn't enough to overpower the speaking or organ, but it was constant through the 30 minute broadcast. Based on user feedback it did seem to subside a little bit the longer someone spoke at the microphone.

We are just using the analog audio out straight to the Teradek.

Obviously, without anyone being able to see our setup further, does anyone have any troubleshooting tips for me to look at closer? I'm new to this and don't have anyone locally that is familiar with this system in any way.

I was told Friday that we've never had a successful broadcast out of our building using the church system, so getting as far as I did was apparently a win.

jsorens6 wrote:We are just using the analog audio out straight to the Teradek.

The Teradek is expecting a stereo input. If you're just using a 3.5mm stereo cable, then the Teradek's right channel will just "float" and may be the source of the noise. See if there's a setting to use just the left channel for a mono broadcast. Otherwise, you'll need to somehow adapt the mono/left only output into a "stereo" signal. Also make sure it set so you're using the audio input and not anything from the camera.

russellhltn wrote:

jsorens6 wrote:We are just using the analog audio out straight to the Teradek.

The Teradek is expecting a stereo input. If you're just using a 3.5mm stereo cable, then the Teradek's right channel will just "float" and may be the source of the noise. See if there's a setting to use just the left channel for a mono broadcast. Otherwise, you'll need to somehow adapt the mono/left only output into a "stereo" signal. Also make sure it set so you're using the audio input and not anything from the camera.

Thanks! I'll definitely give that a try next.

russellhltn wrote:Otherwise, you'll need to somehow adapt the mono/left only output into a "stereo" signal.

This post by CalS201 shows how to do just that.

russellhltn wrote:

russellhltn wrote:Otherwise, you'll need to somehow adapt the mono/left only output into a "stereo" signal.

This post by CalS201 shows how to do just that.

Thanks! I was able to put the settings in the teradek to be only left audio input, but I still had the noise.

I'll go through his post and give that a try. Thanks again!

jsorens6 wrote:...we've never had a successful broadcast out of our building using the church system, so getting as far as I did was apparently a win.

Based on your comment above and that you have a Teradek Vidiu, I assume you are in a stake center with a rack of audio/video equipment located somewhere in the bldg (other than the chapel).

jsorens6 wrote:The only problem we had was a low buzzing, or droning noise on the audio.....it was constant.

Listen to these audio noise files (120hz hum and pink noise) to determine what kind of noise you hear.
HUM https://www.youtube.com/watch?v=pf-vULf ... Y&index=26
NOISE https://www.youtube.com/watch?v=ZU8kk41 ... LY&index=2

jsorens6 wrote:We are just using the analog audio out straight to the Teradek..... does anyone have any troubleshooting tips....

Here's some troubleshooting steps to locate the source of the hum/noise.

Step 1: Disconnect the audio cable from the Teradek and do a short webcast. If the hum/noise is still present then the Teradek may have a problem. Borrow one from a neighboring stake or the FM group to confirm.

Step 2: Assuming your audio is coming through EmTech AVDH-1 in the AV rack https://www.emtechelectronics.com/media ... _Front.JPG, set the AVDH-1 Volume control to 75-100%. Change the audio Source Selection switch from "Camera" to "Satellite" to "Aux" while doing a short webcast. If you hear noise while in all 3 positions then the AVDH-1 is probably the source of the hum/noise. Contact the FM group for a replacement.

Step 3: If you hear "noise" (not hum) when the AVDH-1 switch is only in the "camera" position you probably have low audio level coming from the AVDH-1 that you compensated for by raising the Teradek gain (when you raise the gain you amplify the signal AND THE NOISE floor). There is a level adjustment on the back of the unit to correct this. Contact the FM group to have their audio technician come to the bldg and set the correct level, after which you can lower the gain in the Teradek.

Step 4: If you hear "hum" (not noise) when the AVDH-1 switch is only in the "camera" position you probably have a ground loop in the audio cable between the AVDH-1 and the chapel preamp. I have seen this happen in several bldgs when the audio installers connect the balanced cable "shield" to ground at both ends of the cable. The usual remedy is to "lift" (remove) the ground at one end. This is best handled by the FM group audio technician or someone that can identify the proper cable on the back of the AVDH-1.

Hope this helps you find the source of the hum.............

jsorens6 wrote:Thanks! I was able to put the settings in the teradek to be only left audio input, but I still had the noise.

If "Left only" isn't doing it, and the Terakek isn't using the some kind of "combined" setting (camera and audio input), then the problem is somewhere else.

Where are you getting the audio from? If it's the "Record out" in the chapel, then I don't think the AVDH-1 is part of the process.

Based on your comment above and that you have a Teradek Vidiu, I assume you are in a stake center with a rack of audio/video equipment located somewhere in the bldg (other than the chapel).

That is correct, ours is in the library.


Listen to these audio noise files (120hz hum and pink noise) to determine what kind of noise you hear.
HUM https://www.youtube.com/watch?v=pf-vULf ... Y&index=26
NOISE https://www.youtube.com/watch?v=ZU8kk41 ... LY&index=2

It is definitely a HUM, thanks for the references.

Step 1: Disconnect the audio cable from the Teradek and do a short webcast. If the hum/noise is still present then the Teradek may have a problem. Borrow one from a neighboring stake or the FM group to confirm.

I have knocked that one out. It goes away when I take the cable out.

Step 2: Assuming your audio is coming through EmTech AVDH-1 in the AV rack https://www.emtechelectronics.com/media ... _Front.JPG, set the AVDH-1 Volume control to 75-100%. Change the audio Source Selection switch from "Camera" to "Satellite" to "Aux" while doing a short webcast. If you hear noise while in all 3 positions then the AVDH-1 is probably the source of the hum/noise. Contact the FM group for a replacement.

We do have that AV rack. I will try that tonight. Thanks!!

Step 4: If you hear "hum" (not noise) when the AVDH-1 switch is only in the "camera" position you probably have a ground loop in the audio cable between the AVDH-1 and the chapel preamp. I have seen this happen in several bldgs when the audio installers connect the balanced cable "shield" to ground at both ends of the cable. The usual remedy is to "lift" (remove) the ground at one end. This is best handled by the FM group audio technician or someone that can identify the proper cable on the back of the AVDH-1.

Hope this helps you find the source of the hum.............[/quote]

Thanks again! Step 4 will be next in the queue if step 2 doesn't fix it.

russellhltn wrote:

jsorens6 wrote:Thanks! I was able to put the settings in the teradek to be only left audio input, but I still had the noise.

If "Left only" isn't doing it, and the Terakek isn't using the some kind of "combined" setting (camera and audio input), then the problem is somewhere else.

Where are you getting the audio from? If it's the "Record out" in the chapel, then I don't think the AVDH-1 is part of the process.

I am getting it from the AVDH-1 audio out port referenced in the previous post. I'll be checking that out tonight, thanks!

jsorens6 wrote:I am getting it from the AVDH-1 audio out port referenced in the previous post. I'll be checking that out tonight, thanks!

There's certainly opportunity for ground loops as the satellite rack and sound system racks tend to be separate and located in different places. I'm not sure how the AVDH-1 isolates it's inputs or outputs.

The "Record out" jack in the chapel come from the sound system and is transformer isolated - no ground loop issues.

I need to go through the above process to identify/isolate a hum that's been in our stake webcasts for quite a while. I know it's not the Teradek because most of the time I use Wirecast and it has the same hum.

We had this same problem in our satellite rack. We could not isolate or remove it. We have all old analog gear, nothing new or HDMI in that rack other than the scaler for the camera feed to convert video to HDMI.
We ended up moving the Teradek to the Chapel and using the audio out from the chapel and the humming noise disappeared.

The next problem we had was the the audio output jack was a Mic level, not line level. I know the Teradek can take either if you change the settings, but the audio level to the Teradek was not consistent.
We put a mixer in between the wall jack and the Teradek and used line level out to the Teradek.

This resolved our audio issues.

Due to the locations of the Ethernet jack, and the microphone jack, we now have some cables taped to the floor with gaffer tape.
We picked up a pair of Blackmagic Design Micro Converter BiDirectional SDI/HDMI boxes and are using Coax to extend the video from the back of the chapel to the front of the chapel.
https://www.amazon.com/gp/product/B07C2H1K9R

These little boxes are amazing and gets you past the length limits of HDMI. They are USB powered and since the church recommended Sony - HDRCX405 camera is also USB powered, a surge protector with USB ports gets you past the need for wall warts. We went with this surge protector. https://www.amazon.com/gp/product/B071X9XNWR
We also bought some hook&loop(velcro) cable ties and just strap everything up to the tripod.

studerje wrote:We had this same problem in our satellite rack. We could not isolate or remove it. We have all old analog gear, nothing new or HDMI in that rack other than the scaler for the camera feed to convert video to HDMI.
We ended up moving the Teradek to the Chapel and using the audio out from the chapel and the humming noise disappeared.

The next problem we had was the the audio output jack was a Mic level, not line level. I know the Teradek can take either if you change the settings, but the audio level to the Teradek was not consistent.
We put a mixer in between the wall jack and the Teradek and used line level out to the Teradek.

This resolved our audio issues.

Due to the locations of the Ethernet jack, and the microphone jack, we now have some cables taped to the floor with gaffer tape.
We picked up a pair of Blackmagic Design Micro Converter BiDirectional SDI/HDMI boxes and are using Coax to extend the video from the back of the chapel to the front of the chapel.
https://www.amazon.com/gp/product/B07C2H1K9R

These little boxes are amazing and gets you past the length limits of HDMI. They are USB powered and since the church recommended Sony - HDRCX405 camera is also USB powered, a surge protector with USB ports gets you past the need for wall warts. We went with this surge protector. https://www.amazon.com/gp/product/B071X9XNWR
We also bought some hook&loop(velcro) cable ties and just strap everything up to the tripod.

Thanks for this information. As of today we still haven't been able to resolve it. FM group has dispatched the EMCOR audio tech to meet with me tomorrow morning. I'll have this piece of information handy.

studerje wrote:We had this same problem in our satellite rack. We could not isolate or remove it.............
We ended up moving the Teradek to the Chapel.......................... The next problem we had was the the audio output jack was a Mic level, not line level.......................We put a mixer in between the wall jack and the Teradek and used line level out to the Teradek.

Mikerowaved wrote:I need to go through the above process to identify/isolate a hum that's been in our stake webcasts for quite a while. I know it's not the Teradek because most of the time I use Wirecast and it has the same hum.

Don't live with these audio problems. Talk to your Stake PFR and have him put in a work request to your FM group to get the problems corrected. It will make your job easier and it doesn't cost you anything!

CalS201 wrote:

studerje wrote:We had this same problem in our satellite rack. We could not isolate or remove it.............
We ended up moving the Teradek to the Chapel.......................... The next problem we had was the the audio output jack was a Mic level, not line level.......................We put a mixer in between the wall jack and the Teradek and used line level out to the Teradek.

Mikerowaved wrote:I need to go through the above process to identify/isolate a hum that's been in our stake webcasts for quite a while. I know it's not the Teradek because most of the time I use Wirecast and it has the same hum.

Don't live with these audio problems. Talk to your Stake PFR and have him put in a work request to your FM group to get the problems corrected. It will make your job easier and it doesn't cost you anything!

yeah, we plan to. the problem is that we had them out once. they just showed up, no call no notice, said they fixed the problem and closed the ticket. Just need to get around to opening another ticket.

Update.... FM group is replacing our Teradek unit this week. They haven't been able to figure out what has been causing the problem yet. Fingers crossed!

jsorens6 wrote:Update.... FM group is replacing our Teradek unit this week. They haven't been able to figure out what has been causing the problem yet. Fingers crossed!

Your previous post mentioned you moved the Teradek to the chapel and you no longer had any "hum" issues. So it can't be a bad Teradek.

Sounds like you need to request a technician with knowledge and experience specific to troubleshooting audio issues. FM technicians are usually what I call "generalists" --- jack of all trades, master of some--- so you may need to specifically request the FM to bring in an audio specialist. In my previous area the FM group would fly in a specialist a few times a years to visit several bldgs over a few days and fix all the more difficult audio issues.

CalS201 wrote:

jsorens6 wrote:Update.... FM group is replacing our Teradek unit this week. They haven't been able to figure out what has been causing the problem yet. Fingers crossed!

Your previous post mentioned you moved the Teradek to the chapel and you no longer had any "hum" issues. So it can't be a bad Teradek.

Sounds like you need to request a technician with knowledge and experience specific to troubleshooting audio issues. FM technicians are usually what I call "generalists" --- jack of all trades, master of some--- so you may need to specifically request the FM to bring in an audio specialist. In my previous area the FM group would fly in a specialist a few times a years to visit several bldgs over a few days and fix all the more difficult audio issues.

Hum is a known issue when trying to connect the chapel sound system to the EmTech AVDH-1 in the AV room. The Installation guide for the AVDH-1 even suggests the solution - which is add an audio isolation transformer at the back of the AVDH-1. I have attached the installation guide that shows which cable & connector on the rear of the unit - look for the notes labeled #2.

To definitively determine the hum source just disconnect cable #2 and run a short webcast to check for hum. If the hum is now gone, you can first try disconnecting the shield wire from the 3 pin connector, second try removing any jumper between pin2 & 3 . If neither eliminates the hum, then call FM and tell them to install the RDL audio isolation transformer mentioned in note#2.

CalS201 wrote:

jsorens6 wrote:Update.... FM group is replacing our Teradek unit this week. They haven't been able to figure out what has been causing the problem yet. Fingers crossed!

Your previous post mentioned you moved the Teradek to the chapel and you no longer had any "hum" issues. So it can't be a bad Teradek.

Sounds like you need to request a technician with knowledge and experience specific to troubleshooting audio issues. FM technicians are usually what I call "generalists" --- jack of all trades, master of some--- so you may need to specifically request the FM to bring in an audio specialist. In my previous area the FM group would fly in a specialist a few times a years to visit several bldgs over a few days and fix all the more difficult audio issues.

That was someone else responding in the thread that moved their Teradek and it went away.

Replacing the Teradek did reduce the hum about 50% but it's still an issue. As an added bonus, the auto configuration now works for us as well!

Thanks for the additional tip in this comment and the next one. I'll definitely pass it along. Thanks!

Follow up if anyone is following this thread...........we never did resolve the issue. The hum has been consistent through multiple configurations and Vidiu units.

I finally figured out a workaround yesterday though! I pulled out one of the hearing assist devices and used the the audio off that to plug straight into the Vidiu unit and the sound is 10,000% better with no hum.

I hope that helps someone else as well.

jsorens6 wrote:I finally figured out a workaround yesterday though! I pulled out one of the hearing assist devices and used the the audio off that to plug straight into the Vidiu unit and the sound is 10,000% better with no hum.

Sure sounds like a ground loop. An isolation transformer should have solved it (as long as someone didn't try to tie the grounds together.)

russellhltn wrote:

jsorens6 wrote:I finally figured out a workaround yesterday though! I pulled out one of the hearing assist devices and used the the audio off that to plug straight into the Vidiu unit and the sound is 10,000% better with no hum.

Sure sounds like a ground loop. An isolation transformer should have solved it (as long as someone didn't try to tie the grounds together.)

Yup, probably just a ground loop. It happens in many bldgs and has a documented solution in the EmTech AVDH1 commissioning manual (see note #2 in the
attachment) . The EmTech recommended isolation transformer is an RDL TX-10B, but the TX-1A works as well and have an adjustable level control.
https://www.ebay.com/sch/i.html?_from=R ... a&_sacat=0

In 4 bldgs I've had hum issues with, 3 issues were solved with the transformer and the 4th was just a wiring error.