[ardour-users] Analog Input level Monitoring for delta1010LT ?

[Doug McLain]

Jason Jones wrote:

> 
> Thanks for the info.  This is *exactly* what I needed to know.  With 
> this info, I'll be ready to rock on Monday.  As far as JAMin goes, I've 
> never used it.  For now, I don't think I want to learn about it - just 
> because I'm going slightly crazy trying to figure out ardour and this 
> Delta card I got 2 days ago.  Isn't it great how I leave so much time to 
> learn how to do something before I actually do it? :)  Computer nerds 
> are weird... ;-)

I approve.  Swim or die, i say!  Fun, isn't it?

> Luckily, I found the envy24control about 30 minutes before I installed 
> my delta.  I would have gone insane without it.  But, because I'm so 
> inexperienced with it, there are *loads* of stuff I don't know much 
> about.  For instance...  I don't have a clue (or a very big clue) about 
> the loads of faders in the "analog volume" portion of the program.  
> There is DAC, (Digital to Audio Converter, maybe?) ADC (Analog -> 
> Digitcal Converter?), and another one...  I figured out that the DAC is 
> the one I needed to turn up so I could hear the headphones, but that's 
> about it.  The others, I haven't had time to fiddle with.....  Anyway...

Yeah, all of the controls may be a little daunting at first, not to 
mention the potential confusion created with varying number schemes 
within the same app (DAC0-7 vs PCM1-8, etc).

DAC analog vol controls are a direct gain control of the analog signal 
at the analog line pre-amp.  Take envy24control in its default state. 
PCM Out 1/2 are directly routed to H/W Out 1/2.  This means that any PCM 
data that jack sends to alsa_pcm:playback_1/2 (which is PCM Out 1/2 in 
envy24control) goes directly to H/W Out 1/2, which is the analog rca 
line outs 1 and 2.  Any adjustments you make on the monitor mixer page 
will have no effect.  The analog adjustments DAC0 and DAC1 are your only 
control.

If you route H/W Out1/2 to Digital Mix L/R, respectively, now you are 
going to hear whatever audio is on the 'Monitor Mixer'.  DAC0 and 1 
still need to be up, they are at the analog preamp level so always have 
to be up no matter what you assign to your H/W Outs.  Now that you are 
monitoring the Digital Mix, you need to 'send' audio to the Mix to be 
able to hear anything.  On the 'Monitor Mixer' tab, what you will hear 
is what can be seen in the left-most, large Digital Mixer meter.  To 
'send' audio there, simply unmute and raise the levels for whatever 
channels you want to monitor.  For example, to duplicate the earlier 
configuration (PCM1/2 directly routed to H/W1/2), unmute and raise the 
level completely for the *Left* side only on PCM Out1.  Ditto for PCM 
Out 2, except just the *right* side.  Using a typical stereo wav file 
being played back should show you how audio appears on the Digital Mixer 
as you made the adjustments.  Does it make sense why left on 1 and right 
on 2?  PCM1 is the left channel of a typical stereo audio signal, PCM2 
is the right.  If you were to up both left and right on PCM1, you are 
sending the left half of a signal to both sides, creating a mono signal. 
  Do it on both PCM Out 1 and 2, and you have a mono signal at twice the 
amplitude.  I used PCM Out 1/2 here as examples, using a typical stereo 
wav file as an audio source, but this applies to all the ins/outs, etc.

Now, to monitor some live inputs, head down to any of the HW In 
channels, and unmute/up level on an In channel that you have an input on 
(mic, guitar, etc).  Make sure to up the level at the analog pre-amp as 
well, making sure to account for the numbering difference (H/W In 3 is 
controlled by ADC2, etc).  At this point I sometimes run 2 instances of 
envy24control (yup you can do that) so I can watch the level meter while 
adjusting the proper ADC.  Once that is adjusted, unmute and raise level 
on the monitr mixer tab and the audio will be sent to the Digital Mixer 
and you should hear it.  That's that...

The IPGA0-7 adjustments on the analog page is an additional gain boost 
for line inputs.  If you turn up an ADC all the way on a given channel, 
and the signal is still not hot enough, this amplifies it internally, 
thus adding distortion.  In my opinion, anytime you use these you are 
band-aiding a problem somehwere else.

> One other problem we had was....  monitoring / changing the levels of 
> the mic inputs (ins 1 and 2), or any inputs for that matter.  I couldn't 
> find any controls anywhere that intuitively told me "These are the 
> faders you need to adjust in order to control the level of input".  I 
> just assumed the card didn't have that capability.  I read the manual 
> (which, unfortunately, was written for windows), so I knew about the 
> jumpers on the card (mic / line level)..  Is that the only way to adjust 
> the input levels?  I'm kinda sensing that it's not, and I'm just missing 
> something somewhere.  I hope this is the case.

Like I said above, the ADC (and as a last resort, IPGA) sliders adjust 
input level at the analog pre-amp stage.  I have all my analog RCA 
inputs connected to the patch jack (post gain pre-fader on board) on 
each corresponding channel of the board, so my procedure for setting 
input levels is, I have all ADC's up all the way on the 1010LT, and I 
use the gain pots on the board to set input levels.  Basically I'm using 
the board for nothing other than its moc pre-amps, since all my tracks 
are miked inputs.

Doug
-- 
http://nostar.isa-geek.com/