Headset monitor and mics

WA2DVU
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Re: Headset monitor and mics

Postby WA2DVU » Fri Nov 17, 2017 3:47 pm

Thank you Scott for the info. I am not concerned with RX to TX Latency - 100ms is not too bad for my operation. Hooking up "my lashup" is no big deal. I have had no problems with RF floating around the shack. Hopefully with the mixer, RF does not rear its ugly head! Interesting that the hardware for zero monitor latency is in the blue box. Maybe someday we will be able to get rid of the box with a software update. 73, Bill, WA2DVU
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Conrad_PA5Y
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Re: Headset monitor and mics

Postby Conrad_PA5Y » Thu Feb 22, 2018 1:35 pm

I have only just got my ANAN-100D and having previously used an ANAN-10 at a radio club I ended up using a XENYX 802 to route and monitor audio directly. However I never found this to be particularly satisfactory because I like to hear any dynamic effects that I may have in the signal path, All my operating is DXing or weak signal VHF contests and as a result I deliberately compress and frequency limit the TX audio. Scott would describe it as awful :D

On 2m in particular I have a very noisy blower and need downward expansion to keep background noise down to an acceptable level. It is important that you can hear this I feel. Otherwise any breathing as the gate opens prematurely really does sound awful!

So it seems to me that I need to monitor the actual processed audio. Would I be correct in assuming that the lowest latency would be available by driving the line input directly from a mixer and listening via VAC with an ASIO driver? I have both a Behringer UMC202DD and a Focusrite Scarlet 2i2 available, the Behringer achieves around 9.6ms round trip latency with my (soon to be improved) system. I have no concept at this stage just how much latency the audio processing will add. The convenience of the USB version of the Xenyx 802 is appealing but I expect the latency to be too high.

I am also dismayed to find that I can only have one ASIO based VAC running.

Scott the link to your VAC article appears to be broken.

I mean this one.
http://wu2o.dyndns.org/wu2o_vac_tutorial_2.html

Regards

Conrad PA5Y
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Tony EI7BMB
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Re: Headset monitor and mics

Postby Tony EI7BMB » Thu Feb 22, 2018 7:40 pm

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w-u-2-o
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Re: Headset monitor and mics

Postby w-u-2-o » Thu Feb 22, 2018 9:24 pm

The link is working for me.

More to follow on the other questions later.

73,

Scott
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Conrad_PA5Y
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Re: Headset monitor and mics

Postby Conrad_PA5Y » Fri Feb 23, 2018 12:39 am

Perhaps its just blocked at work, it certainly works fine at home. Too late now but I will read it tomorrow.

Regards

Conrad
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w-u-2-o
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Re: Headset monitor and mics

Postby w-u-2-o » Fri Feb 23, 2018 5:54 pm

Conrad,

Sorry for the delay in answering, I was not at home yesterday.

Conrad_PA5Y wrote:...On 2m in particular I have a very noisy blower and need downward expansion to keep background noise down to an acceptable level. It is important that you can hear this I feel. Otherwise any breathing as the gate opens prematurely really does sound awful!
So many great strides have been made in the available audio processing features of PowerSDR. It is now second only to external rack processing or full-on digital audio workstation software. Unfortunately, this does not include the gate/expander. Perhaps someday there will be a gate that has adjustable attack/hold/release times. The expansion ratio is adjustable, that is the gate "percentage" setting. Put that at 100% and it is a pure gate. I've found that 90% works best for me, although I don't actually use the gate, I still perform my noise gating in external DAW software. However, I have moved all of my other audio processing into PowerSDR. If and when the gate in PowerSDR gets more sophisticated, I feel confident I can abandon the DAW entirely at that time.
Would I be correct in assuming that the lowest latency would be available by driving the line input directly from a mixer and listening via VAC with an ASIO driver?
Actually, no. The lowest latency is obtained using a high quality, zero latency audio interface with ASIO support for both transmit and receive. Doing this effectively shortens the audio paths, which are otherwise quite lengthy and torturous (refer to this thread). However, care must be taken to optimize the ASIO driver and buffer settings, and of course the VAC settings, to obtain the lowest possible latency. With a UMC202HD audio interface I could normally do about 10mS better than the "standard" audio path, and although I haven't measured it, I know I am doing even better with my near-zero latency Presonus Studio interface. Bryan, W4WMT, gets some really outstanding performance out of his professional PCIE digital audio card, but that thing costs a mint!
I have both a Behringer UMC202DD and a Focusrite Scarlet 2i2 available, the Behringer achieves around 9.6ms round trip latency with my (soon to be improved) system.
Experience has shown that the Behringer is a superior performer compared to the Focusrite. It has a faster and more stable driver that is easier to adjust.
I have no concept at this stage just how much latency the audio processing will add.
This is where you are going to become disappointed in the latency of the MON function. First, the total latency of the leveler, EQ, CFC compressors and post-EQ create is substantial, measured in many ten's of milliseconds. Then add to that about another 30mS of latency through the low latency transmit filter. The result, even with the most optimized VAC/ASIO setup, is not commensurate with real-time monitoring. This is why you are much better off creating a WAV file recording of your unprocessed audio coming in from the microphone/sound interface (radio or VAC) and then playing that into PowerSDR as a loop using the built-in facilities available via the Wave menu when making adjustments. Rob, W1AEX shows how he does that in his excellent Youtube videos-- see this thread.
I am also dismayed to find that I can only have one ASIO based VAC running.
Someday we may see a new VAC output that carries the same audio stream that goes to the radio CODEC. Preliminary work has been done on this and perhaps it will get into a future version of PowerSDR.

73,

Scott
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Conrad_PA5Y
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Re: Headset monitor and mics

Postby Conrad_PA5Y » Fri Feb 23, 2018 11:33 pm

Scott thank you.

Its very late now because I have been on EME, however I will make some comments tomorrow. It seems like I will be buying a small mixer and maybe running a gate as a VST plug in. I have some good ones. Great idea with the loop, now why didn't I think of that!

I suspect that Bryan, W4WMT is using an RME Hammerfall then. I have an audio engineering background so I know what is out there.

More to follow.

73

Conrad PA5Y
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w-u-2-o
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Re: Headset monitor and mics

Postby w-u-2-o » Fri Feb 23, 2018 11:50 pm

I don't remember the make, but I believe that Bryan is using a multi-channel rack mic pre-amp with AES outputs and is feeding that into an AES IO card. He is also using a Bodnar GPSDO with dual outputs such that one output is a 48KHz world clock to the audio equipment and the other is 10MHz to the radio. Since they are phase locked he has zero under/overruns in the VAC buffers. Not your average setup! :mrgreen:

I will say that the Presonus Studio 192 Mobile I have is quite fast. The only other USB 3 interface I can think of at any sort of reasonable price is the Zoom UAC-2, but I don't know of anybody who has tried it yet. The low price and reasonably good performance of the Behringer UMC202HD is hard to beat for best value.

If you haven't already, I recommend you peruse the various "stickied" audio threads in the PowerSDR sub-forum.

73!

Scott
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Tony EI7BMB
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Re: Headset monitor and mics

Postby Tony EI7BMB » Sat Feb 24, 2018 12:10 pm

This is not a bad price for USB 3 Conrad https://www.waltons.ie/home/products/vi ... interface/
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Conrad_PA5Y
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Re: Headset monitor and mics

Postby Conrad_PA5Y » Sat Feb 24, 2018 12:32 pm

The UAC-2 on paper looks very good but the drivers can make or break a product so I would be reluctant to be the first to buy one. The price of the of the Presonus Studio 192 Mobile is way too high for me, I need faster PC before I start splashing out on high end sound cards. Anyway hopefully over the weekend I will get chance to experiment a little.
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Conrad_PA5Y
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Re: Headset monitor and mics

Postby Conrad_PA5Y » Wed Feb 28, 2018 6:31 pm

I played it safe(ish) and bought a Behringer UMC404HD,

I will use a virtual mixer and therefore it has enough ins and outs to route my audio from various other radios. The direct monitoring seems a little more versatile than the UM202HD with the addition of a 'mix' control which allows simultaneous monitoring of the playback and direct audio, the ratio can be varied with a pot. One thing that I was not able to find out is how the 4 channels are presented in windows, hopefully as a pair of stereo channels but that is by no means guaranteed. I find that trawling the forums for information is not that productive as you get contradictory information. There are a few you tube videos to watch so maybe that will make things a little more clear.

I should be able to use ASIO on VAC 1 and a none ASIO output on VAC 2 to achieve simultaneous routing of RX1 to WSJT A and and RX2 WSJT B for the H and V polarization respectively, latency is not much of an issue for that particular application. Truthfully I do not know if it will work as expected but I paid under 100 Euros so took a chance.

It will be here next week.

I think that I will also buy Reaper, it seems to have a very versatile mixer and for $60 it is a bargain. Besides I fancy using it for its intended purpose, if I ever find the time.

Then I start with CW, I don't care for break in of any type due to relatively slow TX/RX relays but I do expect this to be 'interesting' as well.

73

Conrad PA5Y
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w-u-2-o
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Re: Headset monitor and mics

Postby w-u-2-o » Wed Feb 28, 2018 8:38 pm

Conrad,

I don't think you are going to be able to do what you want if you use two different drivers on VAC1 and VAC2. The performance differences between the various drivers cause ASIO output to appear many milliseconds before WDM or MME output. The delay is clearly audible. Hence you will likely be better off if you use WDM or MME for both VAC1 and VAC2, assuming you need the audio output from RX1 and RX2 to be synchronous.

And, because VMB does not provide more than two virtual channel strips, that might also pose a challenge. You may actually be better off using a number of Muzychenko VAC cables. You'll have to figure that out.

Personally, I'd like to see an option for VAC1 to carry VAC2 data, in a fully synchronous fashion, on a third and fourth audio channel. That would be fully supported by VMB, as it can handle 8 channels per virtual channel strip (normally for handling Dolby 7.1 audio, but, hey, if it works...)

73,

Scott
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Conrad_PA5Y
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Re: Headset monitor and mics

Postby Conrad_PA5Y » Thu Mar 01, 2018 12:22 am

Hello Scott. The latency difference between VAC1 and VAC2 does not matter for fixed H and V channel WSJT EME decoding. As long as the worst case is delay less than 1 second or so. More than this and weak decodes may fall outside of permitted EME delay parameters, especially with new stations who often do not understand the importance of an accurate PC clock. The decoders operate independently of each other and do not require that the streams are coherent. There is no need to listen to the audio and so this will work. I have done something similar previously with audio from 2 transceivers and 2 sound-cards.

On the other hand the ability to stream coherent IQ data from RX1 and RX2 would be a MAJOR plus for use with adaptive RX applications, I currently use an Afedri AFE822x 2 channel SDR with a pair of 144/28 transverters with a common LO and Linrad/MAP65. This is coherent and fully adaptive but it would be much better to use the transverters >ANAN-100D > MAP65 or ANAN-100D> LINRAD > MAP65 as a coherent RX system. I knew that this was not possible and that it is unlikely to happen any time soon so I am not disappointed. It's a real shame because the hardware can support coherent operation.

Regards

Conrad

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