[ardour-users] monitor questions

Mark Knecht markknecht at gmail.com
Wed Dec 20 06:37:13 PST 2006

On 12/20/06, Atte André Jensen <atte.jensen at gmail.com> wrote:
> Hi
> I'd like to have the sound of the track being recorded mixed with the
> sound of playing tracks. Basically my setup is a microphone connected
> directly to the computer with headphones connected. It would be nice to
> be able to set the monitor level independently from the level going to
> disc + possibly apply a tiny bit of reverb.
> So I read http://ardour.org/manual/recording/monitoring and have a few
> questions:
> 1) I'm currently running jack with a latency of 23ms. Is that too much
> for software monitoring and what's the optimal latency (besides "as
> little as possible"). Also how is software monitoring setup in ardour?
> 2) I guess hardware monitoring could be accomplished by simply
> connecting the input of the mic to the output of the sound card in the
> connections window in qjackctl, right? But by doing this the only way I
> have of controlling the level of the recorded signal coming to
> headphones is by adjusting the input level of the mic. Should I have
> another (simple) application running that sits in the monitor signal
> chain to adjust volume, and if so what would be a good choice?
> --
> peace, love & harmony
> Atte

   Hi. I hope I'm understanding both what you want to do and your
setup correctly. If I'm mistaken then take the following with a grain
of salt.

   If the mic is USB and the sound card is some other hardware device
then I do not think you can do 'hardware' monitoring at least in the
sense that I think about it.

   Imagine the audio path:

1) Sound into mic.
2) Mic digitizes and puts it on the USB cable
3) USB is buffered into Jack - one delay
4) Jack mixes it, routes it and sends it toward your monitor path in
the sound card - second delay

You end up with 2 latency delays as far as I know.

   More normally 'hardware' monitoring, then way I know it, is
completely handled within the sound card. With my HDSP9652 and
hdspmixer I can route a specific hardware input directly to a specific
hardware output with no latency delays. If I hear music coming through
the card I can play my guitar and have it be exactly in time with the
music I'm hearing because the guitar I'm hearing never went into the

   In parallel I will record the guitar and then nudge it to be
aligned, if necessary, but the audio I hear just goes through the
sound card.

   Some low-end sound cards support hardware monitoring in them. You
can route a mix input to the output using some mixer or I suppose Alsa
commands from a terminal. (Tom complicated for me!) Almost all the
high-end cards are going to support this feature.

   I do not think that any audio path that goes into the computer and
through Jack is considered 'hardware' monitoring.

Hope this helps,

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