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Discussion Starter · #1 · (Edited)
Hey Guys,

So I currently have a build log/rant/blog going on over here in the Build Log Section.

It's all installed more or less wired in and working ok...
quick rundown for those who haven't read the log/blog/rant
Equipment
  • Android 6.0 Headunit to USB DAC
  • Burr Brown PCM2704 USB to S/PDIF Circuit Coaxed to
  • MiniDSP C-DSP 6x8 running via a custom shielded multicore to
  • PDX-V9 and a D1004 Pioneer Class D for Rear Fill
Driving
  • Polk db6501 Fronts
  • Factory Coax Rears
  • Rockford Fosgate P1S4-12 Sub in a 1 cu Ft Sealed Box

for the moment the rears are of no concern to me, they are still there running on a basic Class D Pioneer amp just in case i want to fiddle with Rear Filling (I have another thread about that somewhere here)

after extensive reading here and else where I've made a start on tuning this system, but having a few issues making sense of it all.

I've already read most of the basic threads here about crossovers, impulse response, T/A with the USB UMIK-1, T/A with inverted Phase Sub Cancellation etc.

so someone correct me if I'm wrong but the general jist of it is
  1. Install system and verify it's all working
  2. Check Gains/Levels on the physical side (amps, HU) and adjust to maximise signal without clipping
  3. adjust levels on the DSP to a reasonable level (what is reasonable? I'm getting reasonably consistant response across the system around 75db)
  4. Time Align Drivers
  5. Figure out Crossover Points and Set them to each driver
  6. EQ Each Driver 1 by 1 (in my case on the output side)
  7. EQ entire system as a whole (in my case on the input side)

First Question: What level should I be doing my RTA at?
currently I have it set to have a reasonable headroom and roughly what I would listen to at in the car, which turns out to be about a 75-80db level on REW Graphs and target EQ.

I do most of my testing and REW work currently outside of the car all together, I have the UMIK set up in the car, laptop outside the car and I remotely log into the laptop from inside the house and work from there on a much bigger screen :happy::happy: so even if i wanted to change the levels much I would have to walk back outside into the garage :laugh:

Second Question: Time Alignment of the Front Stage
so currently I'm doing T/A with the mic at where my head would be in the drivers seat, fixed position since i'm not actually IN the car to wave it around like kyle does on youtube (blessing himself with his mic... :wacko:)
it's pointed vertically where my head would be and I'm using the 90 degree calibration file in REW, seem about right?

so initially i followed the guide in this guide on how to do T/A with the UMIK-1 and impulse response graphs to which I got this graph in the end for the T/A of the front 4 drivers



which to me seems aligned...at least for the first sections of the wave, any other anomalies coming up there are limited to the T/A step size i have in the miniDSP.
which brings me to this issue, the values I used to get the above graph don't correspond to what I've read on T/A by physical measurement at all as below. It was measured with a 3000-3001hz Sweep on all drivers, no crossovers or EQ. the T/A Values seem to satisfy aligning the graph(unless i'm reading it wrong) but it doesn't make sense mathematically. The measurement was from the single mic, fixed in the drivers head position for all measurements.
If i recall I did
  1. FLS Reference Speaker at 3k
  2. Align FRS to FLS
  3. Align FLT to FLS
  4. Align FRT to FLS
which is why FLS has a 0ms delay since it was the reference point.



now I haven't done at T/A on the subs yet(we'll get to that) or the rears, but it doesn't sound half bad in the car at the moment, but the issue I have it it doesn't make sense for the Right side to have such a high delay, seeing as I'm in Australia, and we have Right Side Driver Seats.... so technically the Right side Drivers are the closest to me. :|
which brings me to the next question

How does one check or accommodate for speaker phase in this particular setup?


I understand that a speaker phase is directly related to that of a Time Delay as a sine wave phase inversion is really just also a delay of x ms for said sine wave, Time delay changes according to frequency I've read so you never get a perfect response, but you are trying to T/A so that they are in line during the crossover frequencies? I ask that because during the testing I had to invert the Front Left (passenger) side tweeter to make things work, I suspect it may be incorrectly wired (I still used the factory wiring to and from the amp,luckily the factory amp was active x-over as well, thus each speaker was wired 1 to 1).

how would one use REW to test the speaker phases?
in such a way that I can systemically test and check which speakers I have to invert before doing the T/A, EQ and other tuning.

Basically I suppose I would be asking, how should I be doing my T/A other than physically measuring it out with a tape measure as I did originally but wasn't happy with the results. Clearly the Tape Measure way doesn't account for driver phases or frequencies either.

Selecting Crossover Selection Points
so I've used these Polks before in a previous install, and thus found myself a used set for this installation, however this time active x-over.
I've already done full range sweeps on all the drivers in the install, and am trying to work out how to use this information to find out the best crossover point for all the drivers.

now according to Jazzi's tuning guide(of which is great help though I'm not sure what the theory behind the x-over selection is for subwoofers) once i add in the Qts Fs and other specs of my sub into the guide, I get a x-over of 63hz. So that's currently my only starting point for crossover frequencies.
this is the response curve for all my drivers so far tested 1 by 1, no EQ or x-over(except for the amp imposed 600hz max one for the subwoofer).


Drivers are:
Red: Sub woofer
Pink: Front Right Tweeter
Teal: Front Left Tweeter
Gold: Front Left Mid Bass
Green: Front Right Mid Bass

as is pointed out on the graph there seems to be a natural crossover at 3.4k roughly where the mids drop and the tweets rise, would this be my crossover point? or is there a different way to do it.
I seem to recall something about using driver phase data to find a crossover point instead of the SPL graph, but I don't know how to read any of the other REW graphs :(

currently I am using 3.5k as my x-over point, it works okay, but would like something to back up my choice with empirical data.

lastly how do I T/A the sub woofer to the front stage?

there seems to be 3 main ways
  • TA by distance
  • TA by impulse response? (HolmImpulse?)
  • TA by sub inversion then trial and error delay till freq cancellation then invert back
I tried inverting the sub at it's xover point (63hz in my case) and finding out when it cancels out the most with the front drivers and then inverting it back and voila, we SHOULD have perfect bass. It sounds easy but I couldn't get it to work, ostensibly because something is probably off with my front stage tuning setup... I just couldn't get any significant cancellation happening either by RTA or listening.

as a last resort I could have done a physical T/A to the sub by distance, but that doesn't work with the impulse method above used since the base driver require the REW high freq timing signal which the sub can't produce :|

hopefully by methodically documenting my tribulations i can help future users and eventually maybe consolidate this into a guide for future users (especially those wanting to use the C-DSP + REW + UMIK-1 combo) as there isn't much information here specific to that style setup (I read mostly about Helix setups)

any help would be appreciated :thumbsup:
 

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Discussion Starter · #2 ·
I can PM the full test sweep data from REW if anyone wishes to help me interpret the data. :)
Primarily the Phase and Impulse graphs if not point me to where I could read about said graphs ;)
 

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Wave Shepherd
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Hi Twizzly,

You're asking some great questions. I'll try to help.


First Question: What level should I be doing my RTA at?
currently I have it set to have a reasonable headroom and roughly what I would listen to at in the car, which turns out to be about a 75-80db level on REW Graphs and target EQ.
Perfect. You could work a little louder if you like, but if you're measuring at a volume similar to what you will be listening to most of the time, then you should have a high enough signal-to-noise ratio to get good data.


Second Question: Time Alignment of the Front Stage
People love to make this much more complicated than it needs to be. Use a tape measure from each speaker to where your nose is when you're in the best listening position, and plug those distances into one of many time alignment calculator tools (such as my spreadsheet which you seem to already have).

If you get the *acoustic* frequency responses of each of your drivers to match the targets that my spreadsheet also builds, then this is all the time alignment you have to do.

If you do not use my tool to adjust your acoustic frequency responses, then you can use a technique called nulling to find the best time alignment setting pretty quick and much more precisely than using an impulse response (which takes a bit of finesse and a lot of trial an error to figure out exactly what you're looking at).

When nulling, be sure you use periodic pink noise in the REW frequency generator (called Pink PN), and use the RTA module of REW with the following settings: mode RTA 1/48th, FFT length to match the sequence length of the Pink PN generator (default is 65,536), averages none, window rectangular, update interval 1.


How does one check or accommodate for speaker phase in this particular setup?
See my previous answer. If you use my tool to generate targets for your individual drivers' frequency response, then phase is 100% guaranteed to match between drivers. That's the entire point of my tool.

If you do not use my tool, then you'll need to use time alignment to fudge the phase alignment to be close enough. Again, you could try using something like impulse response or one of many other techniques, but nulling is the most simple and most reliable way I have found to do that.


I understand that a speaker phase is directly related to that of a Time Delay as a sine wave phase inversion is really just also a delay of x ms for said sine wave, Time delay changes according to frequency I've read so you never get a perfect response, but you are trying to T/A so that they are in line during the crossover frequencies? I ask that because during the testing I had to invert the Front Left (passenger) side tweeter to make things work, I suspect it may be incorrectly wired (I still used the factory wiring to and from the amp,luckily the factory amp was active x-over as well, thus each speaker was wired 1 to 1).
Acoustic phase is a frequency-dependent time delay. The time delay will be different at every frequency if you have a constant phase change. The important thing to remember is that a pure time delay, such as the time of flight between when a speaker makes a noise and when the noise arrives at your ear, has zero phase change at all frequencies. So when you do time alignment to adjust for the time-of-flight differences between your closest speaker and your furthest one you are introducing absolutely zero phase changes.

The part that is not usually explained well is that a given frequency response will have a given (and unique and predictable) phase response. This is why the "classic" textbook crossover alignments work. A 4th-order Linkwitz-Riley crossover has exactly 360 degrees of phase difference between the high-pass and the low-pass filters at *all* frequencies which means you do *not* need to introduce any other processing to get the two speaker elements to sum together perfectly. You do *not* need to add time delay or anything else. Keep in mind this only works if the *acoustic* frequency response of the individual speakers match the crossover targets perfectly, which again, is the entire point of my spreadsheet tool.

But since this is not explained well usually, people don't trust this information and they do things differently, and then complain when all the pieces don't fit together correctly. Then they write all over the internet about how this or that is absolutely needed to do whatever, and so an echo chamber forms to further reinforce the false ideas that they are coming up with ... all because nobody believes acoustics doesn't have to be hard if you follow a few simple rules! Anyhow, enough ranting about that.


how would one use REW to test the speaker phases?
in such a way that I can systemically test and check which speakers I have to invert before doing the T/A, EQ and other tuning.

Basically I suppose I would be asking, how should I be doing my T/A other than physically measuring it out with a tape measure as I did originally but wasn't happy with the results. Clearly the Tape Measure way doesn't account for driver phases or frequencies either.
You can look at the direction the impulse response goes. The first peak should always point the same direction for all speakers. If you have the polarity inversed somewhere, the first peak will shoot the opposite direction (down instead of up for example). And yes, use the tape measure method. It's the best.


Selecting Crossover Selection Points
so I've used these Polks before in a previous install, and thus found myself a used set for this installation, however this time active x-over.
I've already done full range sweeps on all the drivers in the install, and am trying to work out how to use this information to find out the best crossover point for all the drivers.

now according to Jazzi's tuning guide(of which is great help though I'm not sure what the theory behind the x-over selection is for subwoofers) once i add in the Qts Fs and other specs of my sub into the guide, I get a x-over of 63hz. So that's currently my only starting point for crossover frequencies.
The theory behind the crossover selection sheet in my tool is if you know the right properties of a woofer, how much power you will give it, and how big the enclosure size will be, you can predict the excursion of the cone somewhat reliably. Then you compare the maximum excursion to the Xmax of the woofer and make sure you don't make the cone move beyond Xmax. The recommended high-pass filter frequency that pops out of that sheet is for the midbass or midrange driver only, and has nothing to do with what subwoofer you're using. You just happen to need to crossover the subwoofer at the same frequency to pick up the bass that the midrange/midbass woofer cannot do.

I'm not sure what numbers you're typing in or where you get them from, but a typical 2-way speaker system like the Polk 6501 should be crossed over around 80hz and not 63hz. They likely do not have enough excursion (Xmax) available to play without distortion with a crossover at 63hz or lower.


this is the response curve for all my drivers so far tested 1 by 1, no EQ.

.............

as is pointed out on the graph there seems to be a natural crossover at 3.4k roughly where the mids drop and the tweets rise, would this be my crossover point? or is there a different way to do it.
I seem to recall something about using driver phase data to find a crossover point instead of the SPL graph, but I don't know how to read any of the other REW graphs :(

currently I am using 3.5k as my x-over point, it works okay, but would like something to back up my choice with empirical data.
Change the vertical axes of your measurement to something like 40-100dB or even more narrow. It is very difficult to see what is happening when the data is compressed vertically like you have it now.

If you want to empirically choose a high-pass frequency for the tweeters, look at the harmonic distortion plot. Below some frequency, the various harmonic distortions will start to rise significantly. You want to high-pass the tweeters above that frequency range so they are playing in a bandwidth where they are not distorting. This is a rule of thumb, and everyone likes to do this differently. Also, sometimes 2x the resonant frequency of the tweeters (called Fs) is usually a safe place to start.

See the chart below for example. Just below 400hz the distortion rises sharply, so a good high-pass crossover point for this driver would be above 400hz, maybe higher.





lastly how do I T/A the sub woofer to the front stage?

there seems to be 3 main ways
  • TA by distance
  • TA by impulse response? (HolmImpulse?)
  • TA by sub inversion then trial and error delay till freq cancellation then invert back
I tried inverting the sub at it's xover point (63hz in my case) and finding out when it cancels out the most with the front drivers and then inverting it back and voila, we SHOULD have perfect bass. It sounds easy but I couldn't get it to work, ostensibly because something is probably off with my front stage tuning setup... I just couldn't get any significant cancellation happening either by RTA or listening.

as a last resort I could have done a physical T/A to the sub by distance, but that doesn't work with the impulse method above used since the base driver require the REW high freq timing signal which the sub can't produce :|
Because subwoofer frequencies are so hard to visualize on an impulse response plot, you'll have an incredibly hard time using that method. Use nulling instead, as you describe above very well, and you'll get the most consistent results. The cancellation you want to see should be as deep a valley as possible, with a symmetrical shape on either side. See my photo below for an example of what to look for. The chart below is the crossover at 300hz between a midbass driver and a full-range 3" driver.

 

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Not going to add much as Jazzi reply is very informative, but....

but the issue I have it it doesn't make sense for the Right side to have such a high delay, seeing as I'm in Australia, and we have Right Side Driver Seats.... so technically the Right side Drivers are the closest to me. :|
If I am reading this correctly, the higher delays would be on the right side speakers (in your case the drivers side). The closer speakers have the higher amount of delay, not the other way around.
 

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Discussion Starter · #5 ·
Perfect. You could work a little louder if you like, but if you're measuring at a volume similar to what you will be listening to most of the time, then you should have a high enough signal-to-noise ratio to get good data.
realistically I could set almost any level, since I don't actually sit in the car for the bulk of it, and thus don't have to endure super loud sweeps :laugh:

If you get the *acoustic* frequency responses of each of your drivers to match the targets that my spreadsheet also builds, then this is all the time alignment you have to do.
so basically I have to play further with the REW EQ to try get my response to fit the target curves from the spreadsheet?

The part that is not usually explained well is that a given frequency response will have a given (and unique and predictable) phase response. This is why the "classic" textbook crossover alignments work. A 4th-order Linkwitz-Riley crossover has exactly 360 degrees of phase difference between the high-pass and the low-pass filters at *all* frequencies which means you do *not* need to introduce any other processing to get the two speaker elements to sum together perfectly. You do *not* need to add time delay or anything else. Keep in mind this only works if the *acoustic* frequency response of the individual speakers match the crossover targets perfectly, which again, is the entire point of my spreadsheet tool.
that I understood and currently am working to EQ to the target curves from the spreadsheet, that said, the Polks have a traditionally quite a bright and sibilant sound I notice(especially the tweeters), currently Whitledge seems to do a good job of taming them, but again the system is far from 'tuned'. hopefully if i can get it to fit the curve right, this will no longer be of issue, however if not, is it advisable to notch out certain frequencies? or does that play with the purpose of the house curves/phase/LR crossover specifications?
that said is there any case we would be using a LR48 over a LR24?

The theory behind the crossover selection sheet in my tool is if you know the right properties of a woofer, how much power you will give it, and how big the enclosure size will be, you can predict the excursion of the cone somewhat reliably. Then you compare the maximum excursion to the Xmax of the woofer and make sure you don't make the cone move beyond Xmax. The recommended high-pass filter frequency that pops out of that sheet is for the midbass or midrange driver only, and has nothing to do with what subwoofer you're using. You just happen to need to crossover the subwoofer at the same frequency to pick up the bass that the midrange/midbass woofer cannot do.

I'm not sure what numbers you're typing in or where you get them from, but a typical 2-way speaker system like the Polk 6501 should be crossed over around 80hz and not 63hz. They likely do not have enough excursion (Xmax) available to play without distortion with a crossover at 63hz or lower.
all the numbers I have put in for the crossover section are of the Fosgate Subwoofer, thus the 63hz, since I don't actually have the details of Fs,Vas,Qes,Qts or so on of the polks but readily have for the subs. that's why i got such a low number of 63hz.

I suspect lost in translation was the need to find 2 different crossover points

Sub > Midbass
Midbass > Tweets

of which currently Sub >Midbass is 63hz at LR24. (low pass and high pass respectively)

Change the vertical axes of your measurement to something like 40-100dB or even more narrow. It is very difficult to see what is happening when the data is compressed vertically like you have it now.

If you want to empirically choose a high-pass frequency for the tweeters, look at the harmonic distortion plot. Below some frequency, the various harmonic distortions will start to rise significantly. You want to high-pass the tweeters above that frequency range so they are playing in a bandwidth where they are not distorting. This is a rule of thumb, and everyone likes to do this differently. Also, sometimes 2x the resonant frequency of the tweeters (called Fs) is usually a safe place to start.


axis fixed, does give a bit of a better view.
going off that alone, the xover will be about 75 for the sub to mid and 3.5k for mid to tweet

I'm having a hard time making sense of the harmonic distortion graphs, in theory waht you says makes sense, you want the drivers to be playing in a region that they aren't distorting, however i can't seem to validate that with the data.




are the graphs for mid and tweet respectively of the driver side.

Because subwoofer frequencies are so hard to visualize on an impulse response plot, you'll have an incredibly hard time using that method. Use nulling instead, as you describe above very well, and you'll get the most consistent results. The cancellation you want to see should be as deep a valley as possible, with a symmetrical shape on either side. See my photo below for an example of what to look for. The chart below is the crossover at 300hz between a midbass driver and a full-range 3" driver.
should I be just running a RTA off REW for this purpose? invert the sub play pink? noise then see where it has destructive interference? I'm not 100% sure about the settings I should be using in the REW RTA, be it smoothing, the Fourier Transform Length or Averages, hence why all my data is sweeps ala Hanatsu's guide.
 

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Discussion Starter · #6 ·
Not going to add much as Jazzi reply is very informative, but....



If I am reading this correctly, the higher delays would be on the right side speakers (in your case the drivers side). The closer speakers have the higher amount of delay, not the other way around.
actually you're right from an acoustic point of view, however my train of thought so far was distance * some value = delay, thus increase in distance = increase in delay, which is counter intuitive to the point of doing the propagation delay in the first place. since we are delaying closer sources to allow sources further away to propagate to our position. However I suspect i'm not the only one to think of that, since we are associating a distance with a time measurement.

so yes you were reading correctly, I was interpreting wrong.
 

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Wave Shepherd
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so basically I have to play further with the REW EQ to try get my response to fit the target curves from the spreadsheet?
Yes.


....... the Polks have a traditionally quite a bright and sibilant sound I notice(especially the tweeters), currently Whitledge seems to do a good job of taming them, but again the system is far from 'tuned'. hopefully if i can get it to fit the curve right, this will no longer be of issue, however if not, is it advisable to notch out certain frequencies? or does that play with the purpose of the house curves/phase/LR crossover specifications?
that said is there any case we would be using a LR48 over a LR24?
You can absolutely cut frequencies you feel are too hot. This is what I did with my Jazzi curve and the cut is mostly in the 1-4khz range. My guess is that most people think their tweeters are too "bright" or "harsh" or whatever so they turn down the tweeters or tune the treble downwards over the entire range from 1-20khz, when actually the sound they find objectionable is in the 1-4khz range and a really broad EQ filter cutting that area is all that's needed. I usually have 2 filters around that area with moderate cuts in the -2dB to -4dB range for each.

A steeper slope like 48dB/octave is useful if you want to play a speaker as low in frequency as possible before you run into the area where distortion gets too high, or you risk damaging it from overpowering the voice coil and melting it. The downside is much more phase shift, which eventually becomes very noticeable.


all the numbers I have put in for the crossover section are of the Fosgate Subwoofer, thus the 63hz, since I don't actually have the details of Fs,Vas,Qes,Qts or so on of the polks but readily have for the subs. that's why i got such a low number of 63hz.

I suspect lost in translation was the need to find 2 different crossover points

Sub > Midbass
Midbass > Tweets

of which currently Sub >Midbass is 63hz at LR24. (low pass and high pass respectively)
Oh, that's what you're confused. That sheet in my tool is to find the HIGH-pass filter setting. So you should be using the specs from the Polk 6" woofers to find *their* high-pass frequency instead, not using the specs from the subwoofer.

I couldn't find much info on them, but it looks like you'd be much better off using 80hz as a starting point with the 6501 set. Certainly avoid 63hz and lower.


I'm having a hard time making sense of the harmonic distortion graphs, in theory waht you says makes sense, you want the drivers to be playing in a region that they aren't distorting, however i can't seem to validate that with the data.
From your graphs, it looks like you are still using the passive crossovers that come with the Polk 6501 set, or you have some electronic crossover engaged already? If you're really running the tweeters without any crossovers, be super careful how loud you are doing measurements. I would not play pink noise to be safe, and when running a sweep have the lower frequency start around 500hz or higher within the sweep window in REW.

You correctly found the spike in distortion on the woofer measurement near 92hz, but we usually don't care as much about it for woofers since we need to play them near their resonant frequency to get the bass we want. The spike in distortion on the tweeter trace is there but it doesn't look the same because the spike in distortion is always relative to the frequency response. Since the tweeter has some kind of high-pass behavior going on, the frequency response is falling below ~2.5khz and the distortion seems like it is flat. But actually, the distortion is getting closer to the trace of the frequency response, and that is what you're looking for. I wrote some stuff on your image, see below.




should I be just running a RTA off REW for this purpose? invert the sub play pink? noise then see where it has destructive interference? I'm not 100% sure about the settings I should be using in the REW RTA, be it smoothing, the Fourier Transform Length or Averages, hence why all my data is sweeps ala Hanatsu's guide.
Yes, invert the polarity of the sub and play periodic pink noise through the sub and a single one of your 6" midrange drivers, all other speakers should be muted. This is the best way to do nulling since it is interactive and you can see the results in real time. I tried to write out the settings for you, maybe you missed it?

When nulling to set time alignment with a subwoofer, be sure you use periodic pink noise in the REW frequency generator (called Pink PN), and use the RTA module of REW with the following settings: mode RTA 1/48th, smoothing should be greyed out, FFT length to match the sequence length of the Pink PN generator (default is 65,536), averages none, window rectangular, overlap to something low like 50%, update interval 1, peak hold to zero, peak decay to zero, and all the checkboxes on the right side unchecked.

See the screenshot below.

 

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so currently I'm doing T/A with the mic at where my head would be in the drivers seat, fixed position since i'm not actually IN the car to wave it around like kyle does on youtube (blessing himself with his mic... :wacko:)
it's pointed vertically where my head would be and I'm using the 90 degree calibration file in REW, seem about right?
So.....I have done all of my previous REW tuning with fixed mic positions, using several positions and averaging them all, while not sitting in vehicle. I recently watched a YT video (I think it was the Kyle referenced above) where he is sitting in the vehicle, using RTA, and taking live measurements while sweeping the mic L/R, and REW takes live averages from there. What is the difference between this method for any REW measurment vs the fixed mic position?

I am about to re-do some/all of my tunning so was considering the "sweeping" method this time around if it was better? I dont hear much talk about it though, so wanted to get opinions on this. :confused:
 

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So.....I have done all of my previous REW tuning with fixed mic positions, using several positions and averaging them all, while not sitting in vehicle. I recently watched a YT video (I think it was the Kyle referenced above) where he is sitting in the vehicle, using RTA, and taking live measurements while sweeping the mic L/R, and REW takes live averages from there. What is the difference between this method for any REW measurment vs the fixed mic position?

I am about to re-do some/all of my tunning so was considering the "sweeping" method this time around if it was better? I dont hear much talk about it though, so wanted to get opinions on this. :confused:
two differents ways of measuring, you have to differentiate between physical sweeping, vs frequency sweeping.

kyle prefers to use an RTA and a noise track and 'averages' by moving the mic around whilst in the car.

Others like myself, prefer to use a frequency sweep that is done via a fixed mic that is averaged out in REW.

which way is better? depends on who you ask.

personally since I run a miniDSP, pretty much all my heavy lifting regarding EQ settings and tuning is within the REW interface, the DSP is just for loading those EQ settings and setting gains.

whereas kyle uses a Helix, which doesn't have direct integration with REW, but he CAN adjust stuff on the fly, and see the end result straight up on the RTA.

something myself and others using a miniDSP can't do as easily, so we rely on the frequency sweep average -> REW EQ -> target house curves -> produce a EQ filter set -> load filter set into DSP -> resweep.

for kyle if i recall correctly its

Noise Track/Generator -> RTA -> Helix DSP live tune -> RTA.

basically kyle's tuning is based on his observation of the RTA, changing settings in the Helix DSP and going back to the RTA to see the result, and so on, which is pretty similar to the workflow most would use with higher end DSP's where you can do filtering and EQ on more than just a few frequencies.

for example I only have 6 PEQ's to work with on my output stage, so that's only 6 EQ filters set around a particular frequency with a particular Q.

since I have so little to play with, I let REW assist me in the tuning, unlike Kyle and the Helix.
 

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two differents ways of measuring, you have to differentiate between physical sweeping, vs frequency sweeping.

kyle prefers to use an RTA and a noise track and 'averages' by moving the mic around whilst in the car.

Others like myself, prefer to use a frequency sweep that is done via a fixed mic that is averaged out in REW.

which way is better? depends on who you ask.

personally since I run a miniDSP, pretty much all my heavy lifting regarding EQ settings and tuning is within the REW interface, the DSP is just for loading those EQ settings and setting gains.

whereas kyle uses a Helix, which doesn't have direct integration with REW, but he CAN adjust stuff on the fly, and see the end result straight up on the RTA.

something myself and others using a miniDSP can't do as easily, so we rely on the frequency sweep average -> REW EQ -> target house curves -> produce a EQ filter set -> load filter set into DSP -> resweep.

for kyle if i recall correctly its

Noise Track/Generator -> RTA -> Helix DSP live tune -> RTA.

basically kyle's tuning is based on his observation of the RTA, changing settings in the Helix DSP and going back to the RTA to see the result, and so on, which is pretty similar to the workflow most would use with higher end DSP's where you can do filtering and EQ on more than just a few frequencies.

for example I only have 6 PEQ's to work with on my output stage, so that's only 6 EQ filters set around a particular frequency with a particular Q.

since I have so little to play with, I let REW assist me in the tuning, unlike Kyle and the Helix.
Thanks, very good info.....
I also have a Mini C-DSP with 6 PEQ's! I guess for me it may be best to stick with the freq sweep and static placements, and tune this way.
 
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