What does a microphone cable look like in Smaart?
Why do I care? Well, this is the very first thing that I recommend that you measure
in Smaart. We want to take little tiny baby steps, right? We're not
going to go out and measure like 10 speakers all at once and some big sound
system. We're gonna measure little things at home so we can practice and this next
step of practice is going to be thinking about expectation answering this
question of do I have good data think about what to expect then we start the
measurement and that's pretty much what we see then we can already start to have
trust in the operating system okay trust in the analyzer so the very first
smallest easiest step I think is to measure a microphone cable so let's take
a look at my setup here here's my audio interface and what do I have I just have
my loop here my Y cable it's plugged into the butt of the audio interface
here
and that is just taking two exact copies to two different inputs on my audio
interface here so then in smart I made sure to give that a name I called it
loop and then over here in the measurement config I made a new pair
called mic cable set the measurement signal to the loop and the reference
signal to the reference it was that easy so here we are in spectrum and if I hit
play on my reference measurement and then turn on the generator with a sine
wave great I see something on the generator now if I turn on the loop
perfect they're exactly the same level I can even zoom way in and see that they
are super good white you can zoom really far in it's amazing there's like no
limit to how much you can zoom in
I wonder if I can get exactly clothes probably not I'm not
going to touch it anymore
okay click out here to zoom back to default now let's head over to my
transfer function let's just say I open this up and nothing's happened yet so I
press G to turn on the signal generator and then at first I don't see anything
so then I look over here on the right and realize how this is xed out so I
need to hit play okay now I'm starting to see something
but I only see a tiny point here what's going on with that well it looks like I
left the signal generator set to sign so of course there's only one point here
right so let's change that back to pink noise where it should be
and I'm gonna reset this graph so that magnitude is here in the top and phases
in the bottom okay this still doesn't look correct I only have information up
until 250 Hertz and I've got this weird shape in the phase what the hell is
happening here well if I look over here on the right I
see that I've got a one in the delay field I'm not sure if that's correct so
I could start turning it down like this or I could just hit the delay tracking
oh it doesn't want to do it look at that so if that doesn't work click find
oh it's still messed up okay if we insert that then it's gonna be all
messed up so what is our problem here well let's check our transfer function
again
table measurement signal is loop then I plug it in all the way
and references ref
what is the problem here well let's check out the signal generator and see
if the problems there oh I have it set the pseudo-random okay so it's been
banded down to below 150 so that's why a I'm only seeing information up to 150
Hertz and be the delay tracker doesn't work ok let's put this back on random
there we go now I can use automatic delay tracking it's still acting funny
let's reset let's click find there we go zero so talking
about expectations when I open this up I'm measuring in my cable I expect the
delay to be zero right it should be zero milliseconds to get from out of the
audio interface back into the audio interface the comparison between the the
trips that those two things take should be zero this should take exactly the
same time to get from one into the other okay from the comparing the input to the
the reference input to the loop input takes exactly the same time right it's
just a Y cable next thing looking at my live impulse response here I should just
see a tick right there's nothing else happening just goes Boop and comes right
back down and I can zoom in on this just for fun yep there it is just a peek
on the magnitude display I expect it to be perfectly flat with a hundred percent
coherence the whole way you can't even see the coherence I'm turning it off and
on but it's just this red line up here okay perfectly flat unless something
weird is going up to my microphone cable and the same thing with the phase right
and if I set this off by point zero one point zero two milliseconds at a time I
think that's one sample and smart then you can see it go off a little bit and
if we go back to where we started with which was our one millisecond offset
then you'll see 360 degrees a phase offset at one kilohertz that's because
the time period of one kilohertz is one millisecond
I set this back to 0 there we go everything perfectly flat tada
microphone cable please if you don't make it past this step let me know write
in a comment below or a question this is just a great step here to do at home to
make sure that everything is hooked up correctly and you've got your
measurement pair set up and you can see yes magnitude yes impulse response yes
phase perfect sound design