Re: Audio Selection

Conrad, PA5Y

Hello where did you read that? I had always assumed that it did and was rather better at it than VAC.  I am very interested to learn how this stuff works.






From: <> On Behalf Of jdow via
Sent: 30 August 2021 00:41
Subject: Re: [SDR-Radio] Audio Selection


I see, VMP does not even try to match clocks dynamically. I guess its author figures that's a bear and a half, too.


On 20210829 15:14:16, Conrad, PA5Y wrote:

That is the best-case scenario for virtual soundcards, but it is dependent on the routing, whether you are using MME, WDM/KS or ASIO . But virtual soundcards have a buffer, to help with under runs or over runs and therefore data may not arrive when expected. To some extent there will be some sample shifting due to timing errors. This means that degradation can occur.


But VMP handles all of this very well and certainly produces the best results.


If you read this:


It is all explained, but you must read the whole thing as well as some hyperlinked pages to get a picture.  I wish that I could find a better reference, there is a lot that I don’t understand, and it really affects my EME operating. If your signals are well above the noise floor then this issues are a lot less important, or at least that is what I observe.




From: <> On Behalf Of Siegfried Jackstien via
Sent: 29 August 2021 23:21
Subject: Re: [SDR-Radio] Audio Selection


What if the soundcard is just a virtual card.....and you have a handfull of them all calculated from your main cpu clock...?!? 

How "exact" are they?? 


Dg9bfc sigi 


Am 29.08.2021 21:34 schrieb "Conrad, PA5Y" <g0ruz@...>:





From: <> On Behalf Of jdow via
Sent: 29 August 2021 21:34
Subject: Re: [SDR-Radio] Audio Selection


Dream along with me.....

You'd think that, wouldn't you; but, only when you figure crystals are all perfectly on frequency including your sound card crystals....


On 20210829 09:30:34, Siegfried Jackstien wrote:

Set all sampling rates to same setting 48000 then no resampling problems...

Greetz sigi dg9bfc 


Am 29.08.2021 17:36 schrieb Gedas <w8bya@...>:

Hiya Conrad, long time. Thanks !

Gedas, W8BYA EN70JT
Gallery at (under repair)
Light travels faster than sound....
This is why some people appear bright until you hear them speak.

On 8/29/2021 7:11 AM, Conrad, PA5Y wrote:

Voice Meter Potato (VMP) also gets my vote. I use it for many tasks including running demodulated audio from SDRCv3 or Linrad (for EME)  to WSJT-X.  I always found Sample Rate Conversion artefacts when using VAC. It has a similar effect to poor phase noise on weak signals with up to 2dB degradation when compared to a radio (K3S or TS-890) and a soundcard. This does not happen with VMP. I don’t know this for sure, but I think if you use soundcard with a decent clock such as a UMC202HD as the master output device this becomes the reference clock. I could be wrong as this is not made clear. However, I am sure that VMP is much better than any other virtual soundcard solution that I could find 18 months ago. It also has ASIO on the virtual inputs which has much lower latency and does not get mangled by Windows.


You can monitor any signal via the main output device. Like a real mixer it as solo buttons.




Conrad PA5Y


From: <> On Behalf Of Siegfried Jackstien via
Sent: 28 August 2021 21:21
Subject: Re: [SDR-Radio] Audio Selection


i use potatoe from the same company ... works superb

also downloaded vac plus vac_a and vac_b and hificable

so now have 4x vac besides the 3 that potatoe brings with .. means 7 virtual cables used here together with the full blown mixer

(and additionalli installed lighthost and a few vst plugins to give my audio a better punch and sound)

so .. i can highly recommend the mixer and the virtual cables

greetz sigi dg9bfc




Am 28.08.2021 um 18:30 schrieb Max Mucci, N5NHJ via

Hello Gedas,

A very helpful software mixer I use for almost everything:

VOICEMEETER by VB-AUDIO – The world´s most used Virtual Audio Mixer & Sound Tool 


Friday, August 27, 2021, 5:23:20 PM, you wrote:


Using a RSPdx with SDRC V3.1 and Laptop with W/10.


All works aok but then I had the bright idea to install VB Audio to get some VAC going so I could run WSJT etc.


That went smooth and was able to make many FB decodes overnight.


1. I wish there was a way to be able to hear what the RSPdx is tuned WHILE it's audio is being ported over to WSJT via the VAC. Is there an easy way of monitoring what the VAC is transferring?


2. The next part has me scratching my head......I am done with WSJT and just want to do some listening on this W10 laptop with the RSPdx. When I go to SDRC/OPTIONS/AUDIO/PLAYBACK/DEVICES I can see my Realtek PC speakers on one line and the VAC on the 2nd line.


I select the Realtek PC speakers, hit OK then re-start SDRC hoping to be able to hear the receiver via the speakers but get zip. Is there an easy way to switch from one to the other? I thought the OPTIONS tab is where I make this selection but apparently not. Thanks


Gedas, W8BYA EN70JT


Gallery at (under repair)
Light travels faster than sound....
This is why some people appear bright until you hear them speak.











73 de Max, N5NHJ (I8NHJ)





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