Re: [Sursound] Strange 'buzz' in Ambisonic recording

[Dave Malham]

Against that, there's the statement that the buzz was also present "less
strongly, in the panned B-format from the soloists mic" where there
shouldn't be any bass gain at all. Sounds to me like something in the
playback set up. Can you go and listen to it on someone else's rig?

 Dave

On 7 May 2018 at 21:41, Bo-Erik Sandholm  wrote:

> I suspect that depending of chosen virtual mic configuration there is so
> much low frequency gain added that you boost the level of the nearly always
> existing 50Hz hum so much that you actually hear it.
> It has sometimes happened to me that I need to lower the input level of the
> signal to the ambisonic decoder otherwise i got signal clipping in the
> processing stage.
>
> BR Bo-Erik
>
> 2018-05-07 18:30 GMT+02:00 Gerard Lardner :
>
> > I'm very much an amateur here, so please forgive what might be a stupid
> > question!
> >
> > I recorded a concert on Saturday (John Rutter's /Gloria /and Karl
> Jenkins'
> > /The Peacemakers/) using an Ambisonic mic and some others. I'm encoding
> the
> > A-format to B-format using VVEncode in Reaper, and panning in the extra
> > mics using Wigware Ambipan. The result is then decoded to surround sound
> or
> > to stereo using VVDecode; all in the same Reaper set-up. I've used this
> > approach before, usually successfully.
> >
> > I find that, when the organ and brass are playing at full volume (I mean
> > in the orchestra, not just in playback), there is a 'buzzing' sound in
> the
> > playback. It sounds harsh, pitched at about 50 Hz. But if I listen to the
> > A-format files alone in Reaper or in VLC Media Player, there is no buzz.
> > Similarly, there is no buzz if I encode the A-format using the
> stand-alone
> > version of VVMic. The buzz is present both in the B-format from the
> > Ambisonic mic and, less strongly, in the panned B-format from the
> soloists
> > mic. It appears to be an artefact of my editing configuration; but it
> > didn't happen in a recording I made, using the same configuration, last
> > month. The only difference since then has been that my old hard disc,
> which
> > had developed some faults, was cloned onto a new SSD.
> >
> > Does this description suggest a specific problem/remedy to anyone? I know
> > I can produce a decent CD using the stand-alone VVMic route and panning
> in
> > the soloists into the stereo mix; but I'd like to get to the bottom of
> why
> > my Ambisonic configuration is doing this now.
> >
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-- 

As of 1st October 2012, I have retired from the University.

These are my own views and may or may not be shared by the University

Dave Malham
Honorary Fellow, Department of Music
The University of York
York YO10 5DD
UK

'Ambisonics - Component Imaging for Audio'
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Re: [Sursound] Strange 'buzz' in Ambisonic recording

[David Pickett]

>> On 7 May 2018, at 17:30, Gerard Lardner  wrote:

>> I recorded a concert on Saturday (John Rutter's /Gloria /and Karl
>Jenkins' /The Peacemakers/) using an Ambisonic mic and some others.
>I'm encoding the A-format to B-format using VVEncode in Reaper, and
>panning in the extra mics using Wigware Ambipan. The result is then
>decoded to surround sound or to stereo using VVDecode; all in the same
>Reaper set-up. I've used this approach before, usually successfully.
>>
>> I find that, when the organ and brass are playing at full volume (I
>mean in the orchestra, not just in playback), there is a 'buzzing'
>sound in the playback. It sounds harsh, pitched at about 50 Hz.

Some more information would be useful.

-- Which ambisonic mic were you using?

-- Does the buzz really only appear when the organ and brass are playing?

-- Is the buzz heard both in loud AND soft passages?

David

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Re: [Sursound] Strange 'buzz' in Ambisonic recording

[Jon Honeyball]

Spectral analysis would be a good clue here — sounds like clipping of LF to me

jon

> On 7 May 2018, at 17:30, Gerard Lardner  wrote:
> 
> I'm very much an amateur here, so please forgive what might be a stupid 
> question!
> 
> I recorded a concert on Saturday (John Rutter's /Gloria /and Karl Jenkins' 
> /The Peacemakers/) using an Ambisonic mic and some others. I'm encoding the 
> A-format to B-format using VVEncode in Reaper, and panning in the extra mics 
> using Wigware Ambipan. The result is then decoded to surround sound or to 
> stereo using VVDecode; all in the same Reaper set-up. I've used this approach 
> before, usually successfully.
> 
> I find that, when the organ and brass are playing at full volume (I mean in 
> the orchestra, not just in playback), there is a 'buzzing' sound in the 
> playback. It sounds harsh, pitched at about 50 Hz. But if I listen to the 
> A-format files alone in Reaper or in VLC Media Player, there is no buzz. 
> Similarly, there is no buzz if I encode the A-format using the stand-alone 
> version of VVMic. The buzz is present both in the B-format from the Ambisonic 
> mic and, less strongly, in the panned B-format from the soloists mic. It 
> appears to be an artefact of my editing configuration; but it didn't happen 
> in a recording I made, using the same configuration, last month. The only 
> difference since then has been that my old hard disc, which had developed 
> some faults, was cloned onto a new SSD.
> 
> Does this description suggest a specific problem/remedy to anyone? I know I 
> can produce a decent CD using the stand-alone VVMic route and panning in the 
> soloists into the stereo mix; but I'd like to get to the bottom of why my 
> Ambisonic configuration is doing this now.
> 
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Re: [Sursound] Strange 'buzz' in Ambisonic recording

[Bo-Erik Sandholm]

I suspect that depending of chosen virtual mic configuration there is so
much low frequency gain added that you boost the level of the nearly always
existing 50Hz hum so much that you actually hear it.
It has sometimes happened to me that I need to lower the input level of the
signal to the ambisonic decoder otherwise i got signal clipping in the
processing stage.

BR Bo-Erik

2018-05-07 18:30 GMT+02:00 Gerard Lardner :

> I'm very much an amateur here, so please forgive what might be a stupid
> question!
>
> I recorded a concert on Saturday (John Rutter's /Gloria /and Karl Jenkins'
> /The Peacemakers/) using an Ambisonic mic and some others. I'm encoding the
> A-format to B-format using VVEncode in Reaper, and panning in the extra
> mics using Wigware Ambipan. The result is then decoded to surround sound or
> to stereo using VVDecode; all in the same Reaper set-up. I've used this
> approach before, usually successfully.
>
> I find that, when the organ and brass are playing at full volume (I mean
> in the orchestra, not just in playback), there is a 'buzzing' sound in the
> playback. It sounds harsh, pitched at about 50 Hz. But if I listen to the
> A-format files alone in Reaper or in VLC Media Player, there is no buzz.
> Similarly, there is no buzz if I encode the A-format using the stand-alone
> version of VVMic. The buzz is present both in the B-format from the
> Ambisonic mic and, less strongly, in the panned B-format from the soloists
> mic. It appears to be an artefact of my editing configuration; but it
> didn't happen in a recording I made, using the same configuration, last
> month. The only difference since then has been that my old hard disc, which
> had developed some faults, was cloned onto a new SSD.
>
> Does this description suggest a specific problem/remedy to anyone? I know
> I can produce a decent CD using the stand-alone VVMic route and panning in
> the soloists into the stereo mix; but I'd like to get to the bottom of why
> my Ambisonic configuration is doing this now.
>
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[Sursound] Strange 'buzz' in Ambisonic recording

[Gerard Lardner]

I'm very much an amateur here, so please forgive what might be a stupid 
question!


I recorded a concert on Saturday (John Rutter's /Gloria /and Karl 
Jenkins' /The Peacemakers/) using an Ambisonic mic and some others. I'm 
encoding the A-format to B-format using VVEncode in Reaper, and panning 
in the extra mics using Wigware Ambipan. The result is then decoded to 
surround sound or to stereo using VVDecode; all in the same Reaper 
set-up. I've used this approach before, usually successfully.


I find that, when the organ and brass are playing at full volume (I mean 
in the orchestra, not just in playback), there is a 'buzzing' sound in 
the playback. It sounds harsh, pitched at about 50 Hz. But if I listen 
to the A-format files alone in Reaper or in VLC Media Player, there is 
no buzz. Similarly, there is no buzz if I encode the A-format using the 
stand-alone version of VVMic. The buzz is present both in the B-format 
from the Ambisonic mic and, less strongly, in the panned B-format from 
the soloists mic. It appears to be an artefact of my editing 
configuration; but it didn't happen in a recording I made, using the 
same configuration, last month. The only difference since then has been 
that my old hard disc, which had developed some faults, was cloned onto 
a new SSD.


Does this description suggest a specific problem/remedy to anyone? I 
know I can produce a decent CD using the stand-alone VVMic route and 
panning in the soloists into the stereo mix; but I'd like to get to the 
bottom of why my Ambisonic configuration is doing this now.


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