You've done all of the hard work to verify your
audio analyzer and we measured a microphone cable and we measured an EQ
and now we're gonna measure a speaker in a room and we're doing this
at home because we want to make sure that we know how to get really good data
and know how to take action on it so then we when we get out into the field
we can move really quickly okay and we're not just sitting there sort of
scratching our heads like wondering is this working correctly like what does
this do what are our expectations around the analyzer when measuring a speaker in
a room what do we expect to see because if I just turn the measurement on right
now this is gonna be a bunch of crazy lines and I'll be like I don't know what
that is if this is my first time measuring a speaker none of it really
makes sense so my suggestion is that we get another trace to compare it to in
this situation I have a JBL prx 615 M right here wouldn't it be great if I
just had a trace that I could load into smart and say here's a JBL PR x6 15 m in
a room that someone else has measured that I can compare it to sometimes you
can do that if you google for JBL PR x6 15m impulse response sometimes you will
find someone out there that has already measured something like this and put it
up on a website you can download it import that into smart do you have
something to look at and say like okay this is someone else measured a speaker
in a room let me see if mine looks like that and then I have something to
compare it to if you are using Meyer sound speakers then it's a pretty easy
process of opening map xt inserting you know whatever speaker you're using put a
microphone in front of that hit predict
and then you have some data here you can say okay this is what this speaker looks
like in an anechoic chamber this isn't what my speaker is gonna look like but
it's going to be similar okay I'm gonna have this sort of amplitude and I'll
have some phase it looks similar to this then at least I know I'm on the right
track with map xt you can actually export all this stuff and import those
traces into smart and you can have your traces there or Sat live but I have all
those and I'm gonna give them to you because when I was at Merlin's mbeans
workshop in Banff back in August another guy in there named beau did all this
work for us and he put it all into a folder and gave it to me now I'm gonna
share it with you so this is what that's gonna look like you've got all of these
TRF files so I'll put a link below this video and you'll just be able to load
these TRF files for any speaker that you want so if we were measuring upq for
example I could just grab this and load it into smart and that's actually what
I'm gonna do because I looked around for a while I was not able to find any
impulse response for a PRI X 6 15m I did find the YZ data and I was thinking like
maybe I can load this into YZ and then I can export an impulse response and then
import that into smart I don't think you can do that if you can do that let me
know how to get YZ data into an impulse response into smart or something like
that but as far as I can tell you can't do that so my suggestion for your
workaround is to load any speaker so in this case I'm gonna load a u P Q 1 P and
the way I did that is just go here import trace data file I've got all my
Mayer sound traces here so I picked another speaker that's just another
similar speaker with a 15 inch low-frequency driver and a high
frequency driver no problem at least have something compared to so here's
that imported trace okay so maybe I'll have an amplitude
kind of like this maybe I'll have some phase kind of like this okay great so I
think I'm ready to go ah but what about the delay
what delay do I expect to see in the delay finder here I have measured my X
32 and I know that the X 32 takes about 0.85 milliseconds just to get in and out
of the console so let's open up a sticky note and make some notes here so 0.85
milliseconds to get through the X 32 then the next thing I need to add is the
time of flight how long is it going to take to get from the speaker to the
microphone through the air well this is about six inches so I put half a
millisecond here because I'm just estimating one millisecond per foot so
six sensors is half a foot so half a millisecond 0.85 plus 0.5 is 1.35 so I'm
going to estimate that that delay finder down there is going to be about one
point three five milliseconds that's the first thing I'm going to look at when we
load this up why do I care about this well if it's something way off like it's
40 milliseconds or negative 500 milliseconds then I know that there's a
problem and I don't have something set up correctly so I'm just always sort of
thinking quickly like keeping my eye on this to make sure something's not going
wrong and it's not something crazy okay enough preamble let's actually take
the measurement
you
you okay so what did we get one point eight
five one point eight five that's pretty close to one point three five okay at
least I know I'm not way off here in purple is my live trace
you
and let me save it let me take the measurement again and actually save the
trace so we can look at it with a little bit more ease and that's hard to see
let's change the color info color green
so not quite the upq right first of all I've got the
microphone super close and it's right in front of the high frequency driver right
so it's not going to be flat because of that and that may also be doing weird
things to the phase reading if I have it so close to the speaker and like really
close to one driver another thing to keep in mind is that we are comparing a
$10,000 speaker in an anechoic chamber to a $500 speaker in a room right in
front of it all these things to keep in mind but now I can make some comparisons
okay yeah here's my amplitude trays sure here's my phase trace and I'm moving it
around with the cursor keys just to get make it a little bit easier to look at
so look I've got a bunch of extra wrap arounds here
okay now in these initial steps I'm not even thinking about why this stuff is
happening I might think about a little bit but I'm mostly just observing like
okay when I measure this speaker in this room at this location with my
measurement microphone at this location what do I see on the graph okay if I
move the microphone then what do I see so in this video I just want to help you
take those first steps so now you can start playing at home and start
practicing measuring this stuff looking at the data and starting to maybe see
where some trends are happening but most importantly I think that practice here
is just learning to read this data the next things I'm going to do are let's
just see what it looks like to move this microphone in the vertical plane and
let's see what happens if we move the microphone farther away those would be
the just first two steps I'll take with you so I'll leave should I leave both of
these traces open let me close the upq trace we'll just use leave this first
trace open and let's watch the live trace as I move the microphone lower I'm
going to turn on delayed tracking
here is our new setting so what's going on the amplitude here well I can see I
have less high frequencies and that makes sense to me because I was writing
from the high frequency driver and now I'm far from it relatively what else
what happened here in the phase this is really weird if we look at the green
trace I'm flat up here in the high end and if we look at the blue trace the
flat area is here in the low end so I think the thing we just discovered
is that when I have when I'm using this delay tracker it's gonna lock on
somewhere and where it locks on that's where the phase is going to be flat so
to my audio analyzer this is zero and everything
now that's wrapping around that's sloping away from it it's happening in
the past okay it's coming in late but in the blue trace now my microphone is
right in front of the low frequency driver so to my audio analyzer this is
now zero and it's locked on here around what six hundred Hertz
everything's sloping up away from it is coming in the future
negative delay okay everything below it sloping up is in the past it's coming
late okay so this is just one thing I learned
from moving the microphone around in the vertical plane that the delay finder is
going to lock on to an area and then that's what's gonna be flat in my phase
response here let's try moving the microphone farther away and see what
that does
alright let's talk about the time first so now I move the microphone farther
away so let's just do a quick estimate here we've got 0.85 milliseconds from
the x32 plus what's our time of flight now I
could get out the measuring tape or my laser distance measure but let's just
say that's about six feet I'm just gonna eyeball it so I'm gonna put six
milliseconds in here time of flight
so that should be then 6.85 milliseconds this is my estimate for around what the
delay locator should be so what'd we get five point seven one milliseconds pretty
close right again just quickly estimating so that I can see is the
delay locator set correctly all right let me close this great so that's the
delay locator amplitude now I can see compared to my previous traces has kind
of balanced out first of all it's obviously lower right because I move the
microphone farther away and I didn't change my preamp gain I didn't change
the offset here so lower level that makes sense I moved farther away and the
phase is now similar to my very first trace
this guy
and that tells me that the delay locator is now locked on to the high frequencies
right it's using that is zero time and now everything below that is arriving
later okay I don't want to say anything else about
what this is or why or what to do with it I just want you now to start taking
these first steps yourself start doing some measurements at home and if you're
not getting these kinds of results let me know if you're having trouble
importing some of these Mayer sound traces that I'm going to give you let me
know if you're not getting these measurements then stop now fix this
before you move forward because you want to be able to get into the field and
immediately start taking these kind of measurements so that you can see what
you're working with and start taking action with the data alright thanks for
sticking with me I know this was a long one so let me know how it works out for
you
sound design