Issue with Behringer XAir12

Rookie2021
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Issue with Behringer XAir12

Postby Rookie2021 » Wed Oct 27, 2021 1:28 pm

First off I'm new to the Anan family of radios and SDR. I recently received the 7000 DLE MKII. Blown away is the best description. NR2 is a godsend for someone in a noisy suburban environment. PS-A is an awesome feature that drew me to this radio also. The panadapter shows it all. There is so much I will need to learn about the potential of this rig that I will not be getting bored for sure.

After coming from acheiving an audiophile type satisfaction from using outboard gear with my previous superhet radios I found the Anan to really not need it. The CFC tools can get you there. Hats off to Rob, W1AEX, for his excellent tutorial on setting this up. OK, with all that said on to the main reason for the post.

In the spirit of experimentation I wanted to try out one of my condenser mics with the radio. I am going into the rear line input and using an iBox transformer for balanced>unbalanced as I understand this radio is unbalanced in the rear. I have ferrite clamped down as a station habit. I used the XAir for preamp and only two Fx: Maxer and Exciter. These are modeled on the Aphex Aural Exciter and Optical Big Bottom. Nothing else being used in the Behringer. On the Anan I am using its EQ and CFC. I am close talking into the mic in an acoustically dead room. Monitor is off and I am using headphones. The Problem: I'm getting delay in my audio. This was never a problem using this unit with my other radios.

I would appreciate any knowledgable feedback. Thanks.
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w-u-2-o
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Re: Issue with Behringer XAir12

Postby w-u-2-o » Wed Oct 27, 2021 2:03 pm

I'm getting delay in my audio.

Please explain further. Do you mean that other people are hearing echo or reverb on your audio when you speak to them on the air? Or do you mean that when you use MON there is substantial delay in your monitored audio? Or do you mean something else?
Rookie2021
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Re: Issue with Behringer XAir12

Postby Rookie2021 » Wed Oct 27, 2021 4:05 pm

Others are reporting the delay. When I use MON I always get so much delay I can not really tell the over air effect.
As stated in the post the monitor is off. I haven't found it useful yet although I know it can be improved upon.
Again, never any issue with this using this unit on my other radios.
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w-u-2-o
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Re: Issue with Behringer XAir12

Postby w-u-2-o » Wed Oct 27, 2021 4:42 pm

You really didn't answer the question very clearly, but I'm going to assume by "delay" you mean echo or reverb.

This is a classic sign of RFI getting into your microphone (most likely) or into your Xair or iBox (less likely).

The reason it exhibits itself as echo is because the delay from microphone to antenna in SDR architectures like the one we all use is pretty long. The shortest you can practically make it with absolutely zero processing of any type (leveler and everything else off, off and off :) ) is about 30ms or so. With Xair processing and the rest of the things you normally use in Thetis (leveler, EQ stages, CFC, etc.) this can stretch to well over 100ms. Thus when you speak into the microphone, you get the first instance of that speech over the air 100ms (give or take) later, this delayed version gets back into the microphone at a reduced level and comes out 200ms after the first instance as a very clear echo.

Things you can do to fix this:

1) Reduce any stray RF at the operating location.

- Make sure your station grounding and bonding is well executed. Do you use a single point ground in the shack? Is everything, and I mean everything, attached to it? ANAN, amp, tuner, Xair, iBox, PC, etc?

- Add some snap-on ferrites to your coaxial cable, preferably at the antenna feed point. This will reduce any shield currents coming back into the station.

- Make sure all your coax is in good repair and connections are tight.

2) Reduce any remaining stray RF getting into the input of the Xair.

- This can be as simple as adding one or two snap-on ferrites on the mic cable where it plugs into the Xair (Personal note: I had to do this myself where my mic plugs into my audio interface when my antenna was very close to the house. Now with a different antenna further away it's no longer a problem.)

3) Keep any remaining stray RF out of the Xair and iBox.

- More ferrites on power cables and other audio cables.

How close is your antenna to your operating location?
Rookie2021
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Re: Issue with Behringer XAir12

Postby Rookie2021 » Wed Oct 27, 2021 5:24 pm

Ok thanks. Antenna approx 120 ft from the shack.
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w-u-2-o
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Re: Issue with Behringer XAir12

Postby w-u-2-o » Wed Oct 27, 2021 5:40 pm

Try a ferrite on the mic cable, first. That might just nip it in the bud.
Rookie2021
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Re: Issue with Behringer XAir12

Postby Rookie2021 » Wed Oct 27, 2021 8:58 pm

I have a bunch on that cable plus I only use star quad mic cabling. No cigar.
Rookie2021
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Re: Issue with Behringer XAir12

Postby Rookie2021 » Sat Nov 13, 2021 11:28 pm

I'd be interested in communicating with anyone else who has used in the past, or is currently using, the X-AIR unit with their Anan and compare notes. Thanks.
dynamicfusion
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Re: Issue with Behringer XAir12

Postby dynamicfusion » Mon Nov 15, 2021 9:38 pm

I now have several dozen hours behind Thetis and my 7000 dle mk ii. Thetis will always have a delay in it if using the MON feature, there is no way around it. I have reduced mine down to 50 milliseconds and have tried everything. My CPU in my machine is overclocked to 5.5ghz so I know that all hardware up and down the chain is working at optimal spec. This is simply a fact of life that we will have to accept.

Plugged in to the back line in will result in additional latency as the rig has to encode the audio data, send it to the CPU, process it in THETIS, and then send it back to the rig.

VAC has audio delay in its own right, albeit not as much.

My solution was proposed by K1GMM on his youtube. He uses 2 DAC's (i know a little ridiculous) but to apply his theory to your case, you have your behringer 12 that does the processing. This is DAC #1. You then send the line out of DAC #1 in to DAC #2 at line level input channel 1. You can then monitor yourself live without delay. Think about this setup, I have mine setup this way and it works brilliantly. You can turn the thetis MON on at first bootup just to verify you dont have any artifacts or scratchies in your audio.

Feel free to ask any questions.
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w-u-2-o
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Re: Issue with Behringer XAir12

Postby w-u-2-o » Tue Nov 16, 2021 1:26 am

dynamicfusion wrote:I now have several dozen hours behind Thetis and my 7000 dle mk ii. Thetis will always have a delay in it if using the MON feature, there is no way around it. I have reduced mine down to 50 milliseconds and have tried everything. My CPU in my machine is overclocked to 5.5ghz so I know that all hardware up and down the chain is working at optimal spec. This is simply a fact of life that we will have to accept.

This is a well known issue. It has nothing to do with the speed of the computer. You could have a 10GHz processor and it would be no better. The latency is nearly wholly driven by the internal sample rate for audio in Thetis, which is 48KHz, and the topology of the passband filters used. Latency of the linear phase filters in milliseconds is length/48, e.g. for length 2048 that is approx. 43ms. The low latency filters, which are really minimum phase FIR filters, exhibit a latency of approx. 20ms regardless of length. On top of this there is also a number of different buffers, both external to Thetis and internal to Thetis which also add a few milliseconds, but the bulk of the delay is in the filters. Total buffer penalty and filter topology, combined with audio sample rate (again, that is fixed at 48KHz inside Thetis regardless of what VAC is set to), is what defines latency.

Plugged in to the back line in will result in additional latency as the rig has to encode the audio data, send it to the CPU, process it in THETIS, and then send it back to the rig.

VAC has audio delay in its own right, albeit not as much.

The VAC path, properly adjusted, will save approx. 20ms over any path that relies on the internal CODEC in the ANAN hardware.

It's also very important to remember that ANY internal audio processing in Thetis adds latency. Phase rotator, leveler, pre-EQ, CFC, post-EQ, VOX/expander, each stage you utilize adds latency. With all of that in use, latency will exceed 100ms, give or take (I've not measured it in a long time, if you'll pardon the pun!)

My solution was proposed by K1GMM on his youtube. He uses 2 DAC's (i know a little ridiculous) but to apply his theory to your case, you have your behringer 12 that does the processing. This is DAC #1. You then send the line out of DAC #1 in to DAC #2 at line level input channel 1. You can then monitor yourself live without delay. Think about this setup, I have mine setup this way and it works brilliantly. You can turn the thetis MON on at first bootup just to verify you dont have any artifacts or scratchies in your audio.

Given all the delays inherent in digital audio processing, and in particular in Thetis, MON is not a good way to monitor oneself in real time. It is also important to understand that MON is directly picked off of the DAC feed which means it also includes any predistortion if PureSignal is in use. For an accurate representation of transmitted audio PureSignal needs to be turned off.

One needs to make a distinction between mere sidetone and actual real-time audio monitoring. Sidetone is easy if you are using any of the more common professional interfaces like the Behringer UMC202HD, Steinberg, Presonus, M-Audio, etc. All of those interfaces include an internal direct input send to the headphone output which can be mixed with receive audio. Can't speak to how you do that with an XAir.

For real-time audio monitoring of the actual, fully processed transmit audio, things get much more complex. Even the fastest DAW software may not be capable, especially if a lot of complex processing is used. The DAW suffers from the same issues as Thetis in this respect. If you are using old school analog processing equipment things become a bit easier.

Broadcast processors like those from Orban or Omnia represent a worst case in this area. They often exhibit delays of 500ms or greater!
dynamicfusion
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Re: Issue with Behringer XAir12

Postby dynamicfusion » Tue Nov 16, 2021 6:49 pm

Quite right WU2O!

And here I am using an Omnia 9 haaaaaaa.

Fortunately it comes lately with a low latency driver that has 12ms inherent latency, certainly better than the 100+ ms latency on the "high quality mode" (which is really just look ahead limit processing).

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