# Helix and APF



## bnae38 (Oct 3, 2015)

Hi guys,

Hoping to catalyze a conversation on this front (by people much smarter than me ). Still running a ps8 (which i love, but considering a helix).

Finding myself very interested in this method of correction in a limited fashion (as compared to full fir filtering). I have a few spots in particular that are causing cancellation, the biggest of which are troubles between left and right drivers.

Would be a wonderful spot for APF in my opinion, but there isn't a whole lot out there regarding measurement, apf implementation and successful correction of phase cancellation problems.

Hoping someone has played with APF on the helix and had some success doing so, would love to hear about it! Not just for trouble spots but broader phase cohesion. 

Thread might not take off, but worth a shot.


----------



## AVIDEDTR (Sep 11, 2008)

Played with it on a PSIX HELIX amp and from what I can see it only works from 500hz to 20000hz. I found it didn't really help the latest vehicle I was commissioned to tune. 

Needed it from 90hz to 145hz where in my opinion would help the most but I guess helix ran out of memory in the chip.


----------



## AVIDEDTR (Sep 11, 2008)

bnae38 said:


> Hi guys,
> 
> Hoping to catalyze a conversation on this front (by people much smarter than me ). Still running a ps8 (which i love, but considering a helix).
> 
> ...


I personally think the PS8 is reference grade processor and would recommend not to switch for a function that MAY or MAY NOT work for your application.


----------



## bnae38 (Oct 3, 2015)

AVIDEDTR said:


> Needed it from 90hz to 145hz where in my opinion would help the most but I guess helix ran out of memory in the chip.


Hmm that is a bummer, was looking at the 100-200hz range as well.


----------



## AVIDEDTR (Sep 11, 2008)

At home I use second order AP filters thru a rane, which helps with speaker placement / room issues that causes a -13db drop from 70hz to 150hz. I cant move my seating position or speakers away from a wall which contributes to the dip in frequencies. Audibly I have yet to notice anything strange by using AP filters. Without AP filters cuts/boosts of EQ did nothing. With AP filters and EQ cuts/boosts, I was able to recover 11db and finally enjoy listening instead of tweaking.


----------



## bnae38 (Oct 3, 2015)

AVIDEDTR said:


> At home I use second order AP filters thru a rane, which helps with speaker placement / room issues that causes a -13db drop from 70hz to 150hz. I cant move my seating position or speakers away from a wall which contributes to the dip in frequencies. Audibly I have yet to notice anything strange by using AP filters. Without AP filters cuts/boosts of EQ did nothing. With AP filters and EQ cuts/boosts, I was able to recover 11db and finally enjoy listening instead of tweaking.


Cool, good stuff.


----------



## oabeieo (Feb 22, 2015)

You can set a loop back in REw and measure phase real time in RTA
You measure the left driver make it as good as possible take a screen shot and than pan to right and compare and adjust right until lines intersect. 

You can also have rew do a auto "time to mic delay" it sounds out some HF chirps before a measurement. You have to get rid of time to mic delay or phase reading will be ugly and make no sense because of reflection and time difference


----------



## oabeieo (Feb 22, 2015)

The phase control in helix really clears up the midrange 

I wish I knew how to make that kind of phase control on a biquad 

A standard 1st or 2nd order APF will rotate phase to- 180° at a rate depending on the Q of the filter. The helix has the ability to shift increments of 11.5° Over the entire passband of that driver. Minidsp can't do that and the way the helix does it is preferred. I'm sure it can be done in biquad, I just don't know how to assemble one from scratch. To correct myself the non fir minis can't , a fir mini can quite easily with phase eq and actually do a better job of it .( but that's another story) 

If your not all about FIR do the helix that single feature can get you massive strides in imageing by one simple click on midrange.


----------



## thebookfreak58 (Jun 18, 2012)

This looks like a handy explanation.

https://timobeckmangeluid.wordpress.com/2014/02/12/eqin-a-system/

Keen to have a play once it's available for the P SIX DSP MK1


----------



## bnae38 (Oct 3, 2015)

Interesting read, thanks.


----------



## bnae38 (Oct 3, 2015)

:beerchug:

After reading it thoroughly now that I'm not at work (lol), that is pretty damn cool and definitely a great start to this thread..

Fixing phase at Xo is the first thing i wanted to look at.


----------



## bnae38 (Oct 3, 2015)

AVIDEDTR said:


> Played with it on a PSIX HELIX amp and from what I can see it only works from 500hz to 20000hz.


Confirmed (on all products).. bummer. Not much use up there.

Hopefully not a hardware limitation.


----------



## forty5cal1911 (Sep 11, 2006)

Don't know how I missed this thread. 

Fairly disappointed in the inability to utilize APF below 500 even on the newer units with upgraded processors. 

Oabeieo:

Are you currently using a Helix utilizing APF's or have you implemented this in an install or tune?



> You can set a loop back in REw and measure phase real time in RTA
> You measure the left driver make it as good as possible take a screen shot and than pan to right and compare and adjust right until lines intersect.
> 
> You can also have rew do a auto "time to mic delay" it sounds out some HF chirps before a measurement. You have to get rid of time to mic delay or phase reading will be ugly and make no sense because of reflection and time difference


You got any pointers, links or resources for this?

Looking forward to an interesting thread as the new software and hardware is getting rolled out.


----------



## bnae38 (Oct 3, 2015)

I have heard rumors of functionality below 500hz from BlackHhr, but not able to confirm in demo mode??


----------



## AVIDEDTR (Sep 11, 2008)

I tried all channels on the PSIX and LINEOUTS. 500hz to 20000hz is all that was unlocked with 4.06

Sent from my STV100-3 using Tapatalk


----------



## forty5cal1911 (Sep 11, 2006)

I just verified again on the DSP.2 hardware that any band below 500 you attempt to set the APF on resets the Freq to 500.


----------



## bnae38 (Oct 3, 2015)

forty5cal1911 said:


> I just verified again on the DSP.2 hardware that any band below 500 you attempt to set the APF on resets the Freq to 500.


Yeah i saw the same on demo mode, even with the pro mk2. If i bypass it, i can go lower, but it jumps back to 500hz if i uncheck that.

Think everyone is busy with NAB, we'll likely have an answer in a few days .


----------



## BlackHHR (May 12, 2013)

bnae38 said:


> I have heard rumors of functionality below 500hz from BlackHhr, but not able to confirm in demo mode??


Rumors leads to drama.

As I said to you on messages, Until I get to speak to them I do not have an answer for you. Not being able to use the filters below 500 hz ? Until I get training on this, speculation is all I can give.


----------



## bnae38 (Oct 3, 2015)

BlackHHR said:


> Rumors leads to drama.
> 
> As I said to you on messages, Until I get to speak to them I do not have an answer for you. Not being able to use the filters below 500 hz ? Until I get training on this, speculation is all I can give.


****ty move on my part, sorry.


----------



## BlackHHR (May 12, 2013)

AVIDEDTR said:


> I tried all channels on the PSIX and LINEOUTS. 500hz to 20000hz is all that was unlocked with 4.06
> 
> Sent from my STV100-3 using Tapatalk


Just spoke to them in the suite in Vegas. 

It is scale-able in freq from 20 hz - 20,000 hz. Slider (#1) is 500 - 20,000.

Slider (#2) is 32 hz or above from what I gathered from my conversation from a few minutes ago.

Joey will make a video when he returns from Vegas on how to use the APF features.


----------



## AVIDEDTR (Sep 11, 2008)

BlackHHR said:


> Just spoke to them in the suite in Vegas.
> 
> It is scale-able in freq from 20 hz - 20,000 hz. Slider (#1) is 500 - 20,000.
> 
> ...


Slide 1 is 500hz to 20000hz 1st or 2nd order.
Each band 2 to 30 can be 1st order at the freq set by factory default. If you attempt to switch to 2nd order the Freq automatically switches to 500hz and is adjustable to 20000hz


----------



## AVIDEDTR (Sep 11, 2008)

look at the bands


----------



## aholland1198 (Oct 7, 2009)

I emailed AF a few weeks back about this. Said they are working on a solution for below 500. That company is always quick to respond. 


Sent from my iPhone using Tapatalk


----------



## bnae38 (Oct 3, 2015)

aholland1198 said:


> I emailed AF a few weeks back about this. Said they are working on a solution for below 500. That company is always quick to respond.
> 
> 
> Sent from my iPhone using Tapatalk


Thanks


----------



## oabeieo (Feb 22, 2015)

forty5cal1911 said:


> Don't know how I missed this thread.
> 
> Fairly disappointed in the inability to utilize APF below 500 even on the newer units with upgraded processors.
> 
> ...



Slooks like you got it now. Great post btw 

Pointers, well it's a pain in the butt to get it all set up being I had to teach myself how to do it. It took a few months but it's pretty slick 

Set a loop back and either manually or use timing reference get rid of time to mic delay 

Open RTA with some noise 
Check mark phase and play noise you'll see the phase trace . 

Pointer : don't move the mic ....the rest should be pretty self explanatory 
Just get the first side to look parrtellel with the magnitude as much as possible 
The power response will force the phase to descend in frequency in car to about 1k so don't bother trying make it flat , just make it the same on both sides.
( for a one seat car) from mic pos.

Just really want symmetry, it's mostly the differences between left and right in phase that's even audible. Except in LF, 

You won't notice big changes except in minimum phase. If there's reflections the trace will be skewed and may have to move mic closer to speakers and redo t=0
Just try to make sure the mic is directly in front of driver seat if need move forward to account PLd as much as possible.

It won't be perfect, it will just get better. Obviously setting flat FR on both sides first will do most of work for you. So do that first


----------



## forty5cal1911 (Sep 11, 2006)

Thanks for the pointers Oabeieo! That's exactly what I was looking for and is very helpful. You are the man Sir.

Now if it would only warm up so I could actually do some work in the garage for longer than 5 minutes.


----------



## oabeieo (Feb 22, 2015)

forty5cal1911 said:


> Thanks for the pointers Oabeieo! That's exactly what I was looking for and is very helpful. You are the man Sir.
> 
> Now if it would only warm up so I could actually do some work in the garage for longer than 5 minutes.


No problem buddy,
I so much wish I had more time to do screen shots and post up how tos 

You'll figure it out and please share the phase real time .

It's pretty important and not a lot of folks know rew does it , in fact I almost shelled out 800$ for smaart just for that feature and rew did it the whole time


----------



## bnae38 (Oct 3, 2015)

Looking forward to playing with this, thanks for the pointers.

Keep em coming


----------



## bnae38 (Oct 3, 2015)

oabeieo said:


> Slooks like you got it now. Great post btw
> 
> Pointers, well it's a pain in the butt to get it all set up being I had to teach myself how to do it. It took a few months but it's pretty slick
> 
> ...


Hi O,

Trying to set this up just to try. I'm not seeing phase on the rta even with 'show phase of harmonics' ticked. Any ideas?

I know I'm forgetting something stupid, haven't happened upon it yet... :/


----------



## forty5cal1911 (Sep 11, 2006)

Are you generating the signal from REW? Also I don't think pink noise displays the phase needs to be a sweep.

Guess you got your DSP.2 in?


----------



## bnae38 (Oct 3, 2015)

forty5cal1911 said:


> Are you generating the signal from REW? Also I don't think pink noise displays the phase needs to be a sweep.
> 
> Guess you got your DSP.2 in?


Not yet, couple more days . Getting ready. edit: yes I'm generating with REW.

I must be way off base... i was thinking i was reading about phase measurement using PN?

Yeah i had always thought (prior to the last few days) that it had to be done with sweeps.


----------



## bnae38 (Oct 3, 2015)

oabeieo said:


> Check mark phase and play noise you'll see the phase trace .


----------



## forty5cal1911 (Sep 11, 2006)

I haven't been able to get phase response on any pink noise measurements only in sweeps.

I've been playing with this since O posted those pointers and am working out a few things. Hopefully we can get a thread on using the APF to better match phase response right to left as well as at the xover points.

Also, due to the reflections in car it helps to window the measurements AND you need to generate the IR offset.


----------



## bnae38 (Oct 3, 2015)

forty5cal1911 said:


> I haven't been able to get phase response on any pink noise measurements only in sweeps.
> 
> I've been playing with this since O posted those pointers and am working out a few things. Hopefully we can get a thread on using the APF to better match phase response right to left as well as at the xover points.
> 
> Also, due to the reflections in car it helps to window the measurements AND you need to generate the IR offset.


Gotcha thanks


----------



## bnae38 (Oct 3, 2015)

Regarding APF on the helix and 500hz, I got a reply from Julian this morning. See below.



You are correct. With the release of the DSP PC-Tool V4 all supported devices got an allpass filter support. These can be activated manually in the DCM menu.

The actually limited of 500 Hz is a software depended limited which was made due to some low frequency noises we are facing with specific filter adjustments. We are actually working on a solution to remove the limited completely which would allow to adjust the apf in all possible ways. One of the next updates will contain an solution which might shortly mute the channel during an apf configuration.


----------



## forty5cal1911 (Sep 11, 2006)

bnae38 said:


> Regarding APF on the helix and 500hz, I got a reply from Julian this morning. See below.
> 
> 
> 
> ...


That's great news. Thanks for keeping us updated!


----------



## bnae38 (Oct 3, 2015)

Got it finally, friggin USPS sent it San Diego 1st.. grr. Jesus this thing is small lol.

Set the jumper off for signal sense turn on.. Noticed the rcas only accept up to 4v, so I'll take out the Ald line drivers I suppose. Not sure yet if I'm going to install this weekend or hold off a bit for the next firmware release.. Not that I have an idea when that'll be.


----------



## oabeieo (Feb 22, 2015)

bnae38 said:


> Hi O,
> 
> Trying to set this up just to try. I'm not seeing phase on the rta even with 'show phase of harmonics' ticked. Any ideas?
> 
> I know I'm forgetting something stupid, haven't happened upon it yet... :/


Pink noise sure does show phase , 

You have to have a loop back in your sound card . Basicly a cable that goes from an output right back into the input. You'll have to make a sound card cal as well

And there's a setting in preferences that has to be set. Can't remember I think it's use loop back and something else. It's been awhile I'll Re create it and post it. Sorry for delay on getting back to you.


----------



## oabeieo (Feb 22, 2015)

oabeieo said:


> Pink noise sure does show phase ,
> 
> You have to have a loop back in your sound card . Basicly a cable that goes from an output right back into the input. You'll have to make a sound card cal as well
> 
> And there's a setting in preferences that has to be set. Can't remember I think it's use loop back and something else. It's been awhile I'll Re create it and post it. Sorry for delay on getting back to you.


EDIT 
OKAY WTF I can't seem to get it to work now. 

I think when I did do it I had a older version of rew 
Well I know I did , I'll get to bottom of this hang tight I'll ask the guy that made rew on another forum . I know I had it working at least a few times 

(On a side note I wiped my hard drive trying to get a dsp to work since I have installed a newer version of rew, so that's the glitch) 

I will get back to y'all on this may take a day or so .


----------



## bnae38 (Oct 3, 2015)

No worries, thanks man.


----------



## Niick (Jun 3, 2015)

oabeieo said:


> bnae38 said:
> 
> 
> > Hi O,
> ...


 you cannot measure phase in real time with REW. The "show phase of harmonics" is a distortion measurement function. It is not going to allow you to measure the transfer function of your system, only the spectrum. To measure the transfer function (magnitude, phase, impulse response) of your system using REW you have to use the main sweep/measure function. The RTA window in REW won't do it. 

The setting in preferences that you're thinking of is "use loop back as timing reference" which applies to REW'S main measurement feature. It does nothing for RTA measurements, which are inherently single channel spectrum measurement. 

There is a free program that does measure phase in real time using noise, it's ARTA.


----------



## bnae38 (Oct 3, 2015)

Any news?


----------



## oabeieo (Feb 22, 2015)

Yeah . The maker of rew told me that my memory must be playin tricks on me  

This is weird ..... now I'm not sure of myself and am trying to remember what software I was on. I sincerely thought it was rew it must have been another one ....


----------



## oabeieo (Feb 22, 2015)

I've tried a few different trial softwares in last year.
This is really buggin me now. Ya know when you think back and just remember what screen your on and what it looked like. Sorry guys. I guess it's my mistake and now I can't remember what I was using. This frikkin sucks . Having to have wiped my drive is making me feel dumb now.


----------



## bnae38 (Oct 3, 2015)

Huh.. bummer.

John m is a great guy, maybe we'll see it in the future?


----------



## oabeieo (Feb 22, 2015)

He is , I asked him to consider adding it 

real time phase via RTA - Home Theater Forum and Systems - HomeTheaterShack.com

I going to start downloading trials again now to find out what I was doing


----------



## bnae38 (Oct 3, 2015)

oabeieo said:


> He is , I asked him to consider adding it
> 
> real time phase via RTA - Home Theater Forum and Systems - HomeTheaterShack.com
> 
> I going to start downloading trials again now to find out what I was doing


Haha don't sweat it. Thanks man.


----------



## forty5cal1911 (Sep 11, 2006)

bnae38 said:


> Got it finally, friggin USPS sent it San Diego 1st.. grr. Jesus this thing is small lol.
> 
> Set the jumper off for signal sense turn on.. Noticed the rcas only accept up to 4v, so I'll take out the Ald line drivers I suppose. Not sure yet if I'm going to install this weekend or hold off a bit for the next firmware release.. Not that I have an idea when that'll be.


You putting that bad boy in this weekend?  Are you planning to start fresh with your settings or you going to notate your current settings and move them over?

So my question is what would be a drawback to using a Signal Sweep for plotting phase measurement?


----------



## Niick (Jun 3, 2015)

There is no drawback. It just isn't real time.


----------



## forty5cal1911 (Sep 11, 2006)

Niick said:


> There is no drawback. It just isn't real time.


Thanks Nick! Great AudioTools for iOS videos by the way.


----------



## Niick (Jun 3, 2015)

There is a free program called ARTA which can measure real time transfer functions, giving you phase, magnitude, and the utterly, ultra-critical coherence. 

This program can be purchased as well, the only difference between the paid and free versions being the ability to save, import, and export data. 

ARTA might not be as easy to learn, but it does some things that are absolutely critical, in my opinion, that rew doesn't do. The main thing being coherence.


----------



## Niick (Jun 3, 2015)

forty5cal1911 said:


> Niick said:
> 
> 
> > There is no drawback. It just isn't real time.
> ...


right on man, glad you liked 'em 

My video making skills are..... Quite poor, hahaha.


----------



## forty5cal1911 (Sep 11, 2006)

Yeah I'm pretty interested in ARTA and took a run through the User Manual. Can ARTA do those functions independent of the Measurement Box using just a mic?

Also is LIMP the program you would use to perform those measurements?


----------



## Niick (Jun 3, 2015)

Yes, ARTA is broken into 3 programs. There's the main ARTA, then there is LIMP and STEPS. 

LIMP is an impedance measurement program, and STEPS is a really cool, POTENTIALLY super accurate way of measuring distortion. But it can also do some phase and magnitude stuff, too, and if you connect the proper accessories, you can measure things like driver xmax and distortion limited SPL. 

I personally have yet to make use of STEPS. 

I do use LIMP daily, for impedance. 

The main ARTA module is the one you'd use for real time phase, magnitude, and coherence. 

All you need to use ARTA in this manner is the EXACT same things you'd need to use REW, a 2 (or more) channel audio interface, a loop back connection connecting the output of the interface to one of the two input channels, and a measurement mic on the other input channel. USB mics will not work for this. 

The measurement box from the ARTA manual is not needed for this. It's handy for impedance measurements though, using LIMP. I have a similar little jig that I made for impedance measurement. I got my instructions for my impedance jig from the REW help files, as I used to use REW for impedance, but lately it's been giving strange results that don't jive with any of my 3 other main methods of measuring impedance, so for me, REW has been retired.


----------



## bnae38 (Oct 3, 2015)

forty5cal1911 said:


> You putting that bad boy in this weekend?  Are you planning to start fresh with your settings or you going to notate your current settings and move them over?
> 
> So my question is what would be a drawback to using a Signal Sweep for plotting phase measurement?


Gonna hold off I think, wife got her tonsils out the other day. Just kind of whimpering like a puppy most of the time lol, gotta hurt.. Just gonna lay low with her.

I'm going to start fresh with the helix again, starting with figuring out which rew eq filters to use for eq sim.. usm810 works best with ps8, not sure what to expect with helix. Always changing a few things every time I do it over.. going to be boosting nulls a lot less next go around.. I've got a decent idea of what works tonally/visually on overall frequency response so I can come back to that for reference.

Looking forward to playing with apf.. Still hoping the <500hz fix comes out sooner than later. 

I built a remote already and that's ready for install. Knurled silver knobs and a switch. Looks pretty spiffy


----------



## forty5cal1911 (Sep 11, 2006)

bnae38 said:


> Gonna hold off I think, wife got her tonsils out the other day. Just kind of whimpering like a puppy most of the time lol, gotta hurt.. Just gonna lay low with her.
> 
> Looking forward to playing with apf.. Still hoping the <500hz fix comes out sooner than later.
> 
> I built a remote already and that's ready for install. Knurled silver knobs and a switch. Looks pretty spiffy


Yep gotta take care of your wife first thing for sure!

You and me both on the APF's. I intended on working on some phase measurements this weekend myself.... we'll see if that pans out as well.


----------



## bnae38 (Oct 3, 2015)

Yeah in theory it seems like it'll be a solid change.

No more boosting at xo to get proper response.. Or fudging ta to get summing and wrecking arrival times..

Those are the options without it. 

That, and a 170hz cancellation I wanna play with once firmware is released.


----------



## subterFUSE (Sep 21, 2009)

It will be good when they activate APF below 500 Hz, since the midbass region is the most likely place we would need to use them.


----------



## Niick (Jun 3, 2015)

One more quick word of advice. Measuring in-car phase ABOVE a few hundred hertz or so is a non-trivial exercise. 

There will be many who might tell you that attempting to measuring acoustic phase in cars is pointless. 

I personally disagree with this line of thinking, BUT, it isn't an easy thing to do. No matter whether the program you're using has the capability to do it or not, getting USEFUL phase data in the mid to upper frequencies in a car is very tricky.


----------



## bnae38 (Oct 3, 2015)

Niick said:


> One more quick word of advice. Measuring in-car phase ABOVE a few hundred hertz or so is a non-trivial exercise.
> 
> There will be many who might tell you that attempting to measuring acoustic phase in cars is pointless.
> 
> I personally disagree with this line of thinking, BUT, it isn't an easy thing to do. No matter whether the program you're using has the capability to do it or not, getting USEFUL phase data in the mid to upper frequencies in a car is very tricky.


Thanks Niick. I wasn't planning on paying any thought to phase above 500hz, and more likely above 350.

Any thoughts on measuring? Ie single point center of head (probably what I'd try), or another method?


----------



## Niick (Jun 3, 2015)

As far as lower frequency stuff, down there where the phase response is easily readable you're getting into the longer wavelengths, therefore, mic to mic variation is much less significant. So all you have to do is place the mic in the center of where the listener's head would be, and you're good. 

Of course, this isn't the case with mid to upper frequency stuff. Up there as wavelengths get shorter, spatial averaging is king. 

But you seem to be well aware of these general concepts so I'd say you're on the right track


----------



## bnae38 (Oct 3, 2015)

Niick said:


> As far as lower frequency stuff, down there where the phase response is easily readable you're getting into the longer wavelengths, therefore, mic to mic variation is much less significant. So all you have to do is place the mic in the center of where the listener's head would be, and you're good.
> 
> Of course, this isn't the case with mid to upper frequency stuff. Up there as wavelengths get shorter, spatial averaging is king.
> 
> But you seem to be well aware of these general concepts so I'd say you're on the right track


What i figured, thanks.

Looked at some past results and am anticipating my changes.. 

This'll either be pretty cool, or pretty good at making things way complicated/worse. 

Ooo look a phase problem. I'ma fix that. Hey now it sounds worse... Fingers crossed that's not how it plays out lol


----------



## Niick (Jun 3, 2015)

Right! Yeah, it's not hard to really start chasing your tail if you don't have a handle on what's important, and what isn't. 

Did you see the ultra short video I posted a link to that's titled something like "example of need for all-pass filter" 

Here is the link in case you haven't seen it 

https://youtu.be/tWiWxXMXOlk


----------



## bnae38 (Oct 3, 2015)

Cool, yeah my RMB has a spot for it too. Odd...

thx

edit: pic is from hanatsu method sweeps of LMB and RMB, couple oddball results omitted. The right mid bass is wiggy around 160hz.


----------



## oabeieo (Feb 22, 2015)

Thanks for helpin niick . Sorry haven't had time to get to a solution . 

I know I've tryed it , I'll try that one again for sur 

It's pretty beneficial knowing what's happening acoustically.


----------



## oabeieo (Feb 22, 2015)

Niick said:


> One more quick word of advice. Measuring in-car phase ABOVE a few hundred hertz or so is a non-trivial exercise.
> 
> There will be many who might tell you that attempting to measuring acoustic phase in cars is pointless.
> 
> I personally disagree with this line of thinking, BUT, it isn't an easy thing to do. No matter whether the program you're using has the capability to do it or not, getting USEFUL phase data in the mid to upper frequencies in a car is very tricky.


True. However using it to get an idea what's happening at 200hz with a helix phase control would be pretty nice. And if you study single points of mic in midrange (under 800-1k) you can see pattern in the madness that to me makes some sence. Yeah a million breaks in it and the trace jumps all over the place and is almost non sencilcle but the same pattern sometimes pops out and at least makes sence to me. Sorta. IIRC there was smoothing too ....and would stabilize it somewhat no? 

I'm downloading ARTa again right now. :bank head:


----------



## Niick (Jun 3, 2015)

bnae38 said:


> Cool, yeah my RMB has a spot for it too. Odd...
> 
> thx
> 
> edit: pic is from hanatsu method sweeps of LMB and RMB, couple oddball results omitted. The right mid bass is wiggy around 160hz.


I'd highly using "wrapped" phase plots only.......


----------



## bnae38 (Oct 3, 2015)

Niick said:


> I'd highly using "wrapped" phase plots only.......


It's easier for me to visualize what's going on when i unwrap them and lay them out in front of me. Why do you recommend this?


----------



## Niick (Jun 3, 2015)

bnae38 said:


> Niick said:
> 
> 
> > I'd highly using "wrapped" phase plots only.......
> ...


the best way I can answer this is by showing you. Give me a day or so and I'll try my best to make a short video detailing how I use the phase trace and why I recommend this.


----------



## bnae38 (Oct 3, 2015)

Thanks


----------



## forty5cal1911 (Sep 11, 2006)

bnae38 said:


> Thanks


x2 That'd be great Nick!


----------



## Niick (Jun 3, 2015)

My apologies for not having been able to make the phase video yet, but I will, I promise! 

Until then, here is a quote from an article on reading phase data:

"WRAPPED VS UNWRAPPED PHASE
Most measurement systems have the option to ?unwrap? the phase response. This extends the phase graph beyond ±180° and allows you to view the phase trace as a single continuous line. Using this for alignment is a mistake, not only because the graph becomes compressed making it harder to read phase differences accurately, but it is prone to errors due to the way it is calculated. Use with caution!
When we look at an unwrapped phase response, the measurement system actually has to work out when the phase is jumping from +180° to -180° (or vice versa) and then splice the data together to make a single line. Any errors in the measurement can be compounded when the phase is unwrapped. This works fine in electronic measurements, but errors are introduced as soon as you add a loudspeaker and environment. Some measurements also have a group delay option, but this has to be calculated from the unwrapped phase, meaning those same errors also occur in the group delay.
I?ve seen many people (myself included) look for fancier ways to use their measurement systems, but unless you?re working in very controlled environments, know exactly what you?re looking for, and have a specific use for group delay or unwrapped phase, stick to the regular old boring wrapped phase."

The entire article can be found here:

http://www.audiotechnology.com.au/wp/index.php/how-do-you-measure-up-part-iii-the-difficult-phase/

Being that we don't have an intuitive mechanism for understanding the phase trace the same way we do for understanding, say, an RTA display, means that for most people learning to read the phase trace takes time and practice. I know it certainly did for me. And I'm still learning

When I look towards folks who have many more decades experience than I with sound system tuning, acoustic analysis, etc. for advice in these matters, I almost unanimously find them all saying the same thing. That the wrapped phase trace is the one to use. 

But, when I make the video, we will definitely check it out both ways, and with a few different programs, to really get a feel for it.


----------



## bnae38 (Oct 3, 2015)

Niick said:


> My apologies for not having been able to make the phase video yet, but I will, I promise!
> 
> Until then, here is a quote from an article on reading phase data:
> 
> ...


Cool, looking forward to it.


----------



## oabeieo (Feb 22, 2015)

As far as plain ole measurements go what about a 5 cycle window in the IR tab?

Just discovered that recently..... if want to see a bit better the filtered ir can be beneficial 

Niick can you explain how this works ....it depends on the frequencies your measurements are makes it work different. How come?


----------



## forty5cal1911 (Sep 11, 2006)

I have some similar but pretty basic questions.

We know how difficult it is to get accurate phase reading say in the midrange while measuring in vehicle. What is the recommended method to even begin to get an accurate plot on this? Use a windowed / gated measurement of short duration combined (or like O suggests filtered IR?) with close mic position?

Very interested in the methods being used by anyone who is getting results here. Also, it would seem that phase consistency left <-> right within the same driver set would be ideal as well as phase alignment at the crossover point to the preceding driver set.


----------



## oabeieo (Feb 22, 2015)

forty5cal1911 said:


> I have some similar but pretty basic questions.
> 
> We know how difficult it is to get accurate phase reading say in the midrange while measuring in vehicle. What is the recommended method to even begin to get an accurate plot on this? Use a windowed / gated measurement of short duration combined (or like O suggests filtered IR?) with close mic position?
> 
> Very interested in the methods being used by anyone who is getting results here. Also, it would seem that phase consistency left <-> right within the same driver set would be ideal as well as phase alignment at the crossover point to the preceding driver set.



Close mic is the only way. 
Gating will reveal a bigger part and get a few hundred cycles of resolution 

On another forum someone posted a picture of a lightbulb next to two mirrors on two walls in a corner. As a very good analogy of what we see with the measurements. In the picture it looked like 8 lightbulbs , and so it is . 

Our "rooms" are far too reflective and even with a solid filter we can only see a little bit more . 

Have you tryed a filtered IR? It can vary so much depending on distance, location, and surfaces....

I sorta wish I had my pc I'll try and post some screen shots tonight when I get home .


----------



## Niick (Jun 3, 2015)

Let me state first that I am not trying with this post to prove one way or another that phase at upper frequencies in a car should or shouldn't be measured. Many people are convinced that it should not, and not to waste your time trying to measure it. I only want to help those who ARE attempting to measure it, to be able to pull it off. Then, they can decide what to do with the data. 

With that out of the way, lets continue 


So, the easiest way to get reliable, readable, repeatable phase data across the mid to upper spectrum is simply to use Smaart v7.5 or v8. 

Its in-car phase measurement capability is second to none. Dare I say MUCH more usable then the infamous TEF 20 (or 25). More useable because it's WAY faster and real time. 

The TEF analyzers were amazing tools in their day, and actually they still are. There was an old quote from Richard Clark that someone once posted in a thread on this forum:

"i have had my present TEF-20 for several years and presently have no idea what is current--Crown sold their interest in test equipment to Gold Line--what they have done since is anyones guess---i don't know what to recommend--most of the PC based units i have seen are so cheezy i would not advise anyone to shell out good money for them--but thats just my opinion"

Now, this original post was from 2013 I think, and at that time the quote itself was quite old. The TEF 20 analyzer has LONG been out of production, replaced by the TEF 25 analyzer.

These days, EASERA allows TEF measurements to be made entirely software based, thus allowing you to change parameters without having to re-measure. The original TEF machines had a hardware tracking filter that required remeasuring if you wanted to change parameters.

The man credited as the inventor of the TEF machine, Richard C Heyser, is one of my absolute heros.

I say all this about the TEF analyzer so as to make sure that no one gets the impression that I'm in any way discounting the brilliance of the machine or it's inventor. 

Today's reality is that PC based measurement, despite what Mr. Clark might have thought about it decades ago, is now EVERY BIT as capable, and in many instances far more capable, than any of the old hardware solutions ever hoped to be. 

Now, as far as Smaart goes, I say 7.5 or 8 because I have no idea how well earlier versions can pull this off. I have worked with earlier versions, but it was a long time ago and I knew far less about what I was doing even than I do now!) 

With REW, Frequency dependent windowing might be your best way. 

I have a vehicle here (2500 Dodge Truck) that I'm currently building door baffles for. It is going to be running Morel Elate 9 inch midbass in each door. there is also a Morel dome midrange and Morel dome tweeter to complete the front stage. It's all powered by old, great condition PPI "Art" series amplifiers. DSP control is Helix 8 channel. 

The owner has agreed to let me keep the truck till wednesday, which is my day off. By that time the doors will be done and I will make a video showing EXACTLY how I measure phase in cars, and I'll also show REW, Holm, and ARTA. 

Stay tuned.


----------



## oabeieo (Feb 22, 2015)

You have all the cool tools niick. 

Yeah I don't think anyone is trying to prove anything and most of us are rew users and are in the infant stages of learning as much as you know. No body on this forum can explain things as masterfully as well as you can and I don't think anyone that is sharing there experience is saying there way is 100% perfect. Come on it's a chat room not a university so don't be so worried about coming off as a know it all. No one cares we just try and help each other, sometimes it's useful info sometimes not so much, but it sure is fun being able to chat with others and share experience. So please , teach us!  

Like for me, I get mixed results with rew. And it seems the closer I get to the speaker I'm measureing the better it gets, but some times it works decent, that's what I think is the missing factor here the inconsistency and from what I've learned from other knowledgeable folks on forums... I mean , 

As cool as smart v 7-8 is , were not using that platform. So is there anyway you can make it more a Rew orientated . Thanks


----------



## Niick (Jun 3, 2015)

Sometimes I feel that I should clarify my intentions before talking about topics like this, as these discussions have been known in the past to stir up alot of debate. 

yes. my plan is to use v8 to acquire a type of "baseline" reading. Then manipulate the settings in REW until I'm confident that It's more or less telling us the same thing. 

In addition to the in car data, I will have the quasi-anechoic response of the same drive units measured on my baffle, with Hilbert Transform minimum phase overlayed to kind of 'sanity check" the baffle measured response. 

So we'll be able to overlay the "out of car" magnitude, IR, and phase with the "in car"

I'll do this in both Smaart and REW, this way maybe we can get a better idea of exactly how the vehicle effects the measured TF at the listening position. 

It should be fun


----------



## oabeieo (Feb 22, 2015)

Well that's a good ole southern "hot damm" This should b sweet 
J.k. :d 

But seriously, yeah definitely want to see how you control the fine settings within rew. 


On a side note it wasn't arta I was using when I made phase with rew , (but I am playing with arta again....and it's confusing ) it was rew and I was in a calibration of soundcard somehow it showed phase on the RTA window as long as I didn't shut off the calibration. 
Not a intended use of rew , and it was phase of harmonics and somehow was displayed in the RTA window as a phase trace. A guy on the home theater shack showed me how to get to it. So I was completely using it incorrectly that day I got it to show that and couldn't get back. What I did was run a calibration for a loop back for sound card and the noise it generated for setting levels was on and I opened the RTA window while the calibration noise was on and it shows a phase trace. Again not a intended use of rew was not meant to be used like that. But I didn't know , at the time I found it I didn't know what a "window" was ir what "IR" meant . So I blaberjab and than I'm all ****ed up. So
At least I know I wasn't loosing my ****, but it also means even tho I've learned what everything means doesn't mean I know how everything works completely. Definitely a learning curve to this. And when you feel your really starting to get it there's something that hangs you up. Ugh . So yes. Niick dood we would love a super solid tutorial on not how to take measurements we got that, we need to know how to do ALL the hidden features. Dood that would so frikkin tight. I mean yeah I can go and make decent use of ALL of the features rew has and I know decently what it all does. But within the fine details there has to be a better way to decipher this ****.

Okay I'm rambling


----------



## Niick (Jun 3, 2015)

If I remember, I'll try to take a look at the "show phase of harmonics" check box and what it does as well. 

Remember, in order to really get a feel for all of the different settings and how they behave, you don't need to be measuring ANYTHING acoustical. In fact, you don't even need an audio interface or any cables whatsoever. 

All you need is two free programs, Voicemeeter and EKIO.

In fact, with voicemeeter alone you can route REW'S internal generator back into REW and measure pure pink noise or white noise or periodic pink or white noise or sine waves or whatever, all to your hearts content. 

Being able to do this is very handy, because, these signals are predictable, therefore you can draw certain conclusions about what the measurements SHOULD show.


----------



## oabeieo (Feb 22, 2015)

So I'm sure you know all about this niick but I'll tell everyone else. 

So on another forum someone explains a very important thing and maybe I'll share or try to 
Which will make all of this make more sence.

For a long time I've been trying to figure some things out and I believe I'm on the right track now

Phase is measured in degrees right, 
So it's measurements are much like how a circle can be measured from 0 to 360 degrees. 
I've been trying to figure out how do I get the hypothetical circle to mean something in distance from me to speakers. After all the differences in path lengths is causing most of our phase issues to begin with. 

So I just discovered how radians fit into the whole problem. If you look at this radian to degree conversion that was just shared to me (open all the tabs it's in one of them) 

https://en.m.wikipedia.org/wiki/Radian

What you'll find is some math that converts radians to degrees. And if you look at this table you'll find how wavelength fits in the calculation 

http://www.jdbsound.com/art/frequency wave length chart 2013.pdf

To read phase we have to know how all the different conversions work. This is the conversion I have been lacking , and I knew half of it most my life. 

So Basicly. Let's take t=o or the very beginning of a waveform. The time a frequency comes out of a speaker. It's measured against the signal generation (whatever that is) so to simply things let's find out how the phase difference between two speakers at 100hz.

Left speaker is 1 foot away and right speaker is two 2 feet away. Path length difference of 1' or 12". So at 100hz the wave length is 11.25 feet long. So 360° Is equal to 11.25 feet at 100hz. The higher the frequency the shorter the distance. Now to find out where the heck between the path length difference the phase difference is you have to measure the size of the wave length and treat it as a circle representing 0- 360° . Than apply the degree to radian conversion using wavelength as the circumference using plain old 2 Pi r and the radian to degree conversion and you can determine exactly how many degrees of phase is between the drivers. And because of how that measurement math functions is why phase would read on a graph as falling as frequency rises when comparing time domain to frequency domain. Like in our measurements. Which is why we often need to wrap the phase so see it all. 

Anyway I thought it was pretty interesting and I'm decently handy at math and it makes it make a whole lot more sence to know the conversions when trying to read phase measurements and how to make use of the measurements. If I have a problem area I can run the conversion at whatever frequency there's a difference and see how it would change things work in the time domain, after all we live in the time domain and sound travels through it at a certain speed. So you have to know all the mathematics of all the different domains represented in a single measurement and the elegant gearing that joins them.


----------



## bnae38 (Oct 3, 2015)

Fyi 

-----
Hi Ben,



we are planning a release within the next ten days. This release will contain wider adjustment ranges for the apf.



Best regards



Julian Fischer


----------



## forty5cal1911 (Sep 11, 2006)

bnae38 said:


> Fyi
> 
> -----
> Hi Ben,
> ...


Awesome!


----------



## Niick (Jun 3, 2015)

Ok, so it's almost here. I'm actually very much looking forward to making this video  I'll be making the video tomorrow. Here are some pics of the Midbass drivers that will be measured. 

I figured I could show you guys that have been following this thread what Ive been up to over the last couple days, this way too we'll all have an idea of what I'm going to be measuring in the video. 

The vehicle is a 2012 RAM 2500. The owner has until now done all of his own installation. However he doesn't have the time necessary to dedicate to building midbass baffles/mounting structure, so, thats what i did for him. He has also switched from Zapco DC amps to an 8 ch. Helix DSP and PPI "Art" amps. The last time I tuned his system he had the Zapco DC amps. 

here are the pics of the midbass assemblies that I built for him. They house 9" Morel Elate midbass drivers. We decided to go with the grille from the Morel AdMW 9. You can kinda see in the pictures that the assemblies are bolted in from the rear. 

So yeah, this is what we'll be measuring tomorrow in the video. I'm going to try to include as much relevant information as I can. If anyone has any specific questions about measuring phase, just post em and I'll try my best rto address them each in the video.


----------



## bnae38 (Oct 3, 2015)

Wow, nice work. Can't wait for the video, good timing


----------



## forty5cal1911 (Sep 11, 2006)

Looking forward to this Nick! Great looking build. I'm sure your client is going to be *VERY* pleased.


----------



## bnae38 (Oct 3, 2015)

Niick said:


> If anyone has any specific questions about measuring phase, just post em and I'll try my best rto address them each in the video.


Thought of one think Nick. Wondered if you could show different types of xo ie Butterworth bessel lr etc and how that affects measured phase. Curious to see if there is any benefit we can see in phase response by flipping through them.

Then again, there might not be much there.. but since we're going down the phase rabbit hole, might be intetesting?


----------



## Niick (Jun 3, 2015)

bnae38 said:


> Thought of one think Nick. Wondered if you could show different types of xo ie Butterworth bessel lr etc and how that affects measured phase. Curious to see if there is any benefit we can see in phase response by flipping through them.
> 
> Then again, there might not be much there.. but since we're going down the phase rabbit hole, might be intetesting?


Yes, we can absolutely do that. So unfortunately i simply ran out of time the other night, by the time i got the vehicle set up to tune, it was 8 PM.

But worry not, the owner lives right down the street, and we will get er done. I promise. Just keep filling me in on ideas for the video/topics. I work alot better if I have specific questions/ topics than if I just have general ideas. The more specific the better.


----------



## bnae38 (Oct 3, 2015)

No worries.

I guess what I'd like to see is a "simplified" method of measuring phase with rew and what you would consider the best practice for using the phase adjustments at xo in the helix to get the best phase cohesion between drivers in the car.

From there, apf use for trouble spots would be great. My right midbass is goofy around 160hz as i posted earlier. I am not sure what kind of correction would make sense there. A highish Q 2nd order apf at 160hz would bring that area to match the other side, but wouldnt it slope off 360 degrees below the left mid bass above the apf point? (might be wrong). If I'm not wrong, would a 2nd apf be used to bring that back up above 200hz to match the left side?

Hard to say where the line is between useful information and taking things over the top to the point its complicating things; but I'll leave that to you .

Maybe pointers on what is reasonable to try to correct vs what we should ignore would be helpful too.

Thank you sir!


----------



## bnae38 (Oct 3, 2015)

Seems like a lot to ask of you, honestly.

Plz trim things down as you see fit, don't want to ask you to shoot a full blown documentary lol.


----------



## bnae38 (Oct 3, 2015)

Bump. Car troubles on my end.. delaying dsp.2 install further.

Not in a rush anyway since I'm somewhat waiting on the firmware fix.


----------



## bnae38 (Oct 3, 2015)

Looks like new firmware went live 

DSP PC-Tool Version 4 DSP PC-Tool, Audiotec Fischer GmbH | Innovative Car Audio


----------



## subterFUSE (Sep 21, 2009)

Anyone know if the new USB HEC module will charge an iPhone?


Sent from my iPhone using Tapatalk


----------



## forty5cal1911 (Sep 11, 2006)

subterFUSE said:


> Anyone know if the new USB HEC module will charge an iPhone?


According to the manual it does not support charging.

http://www.audiotec-fischer.de/files/BAs/BA_HD-AUDIO%20USB-INTERFACE.pdf

I got the new software in but haven't played with APF yet. Hopefully will get some time this weekend.


----------



## bnae38 (Oct 3, 2015)

forty5cal1911 said:


> According to the manual it does not support charging.
> 
> http://www.audiotec-fischer.de/files/BAs/BA_HD-AUDIO%20USB-INTERFACE.pdf
> 
> I got the new software in but haven't played with APF yet. Hopefully will get some time this weekend.


Cool, looking like next weekend for me. 
:juggle2:


----------



## forty5cal1911 (Sep 11, 2006)

Was really looking forward your phase demo Nick.

I know how it is Ben. I've been covered up with projects at work and haven't really had any time at all let alone for tuning.

So one of my major questions regarding phase alignments is which is most important / effective. Aligning phase at the xover points per channel (ie left and right) to achieve phase continuity from driver to driver or aligning phase per driver set (ie left and right midrange).

As I understand it is difficult to get an accurate phase reading in these ranges without some serious software is it even going to be worth trying for phase alignment left and right in the midrange.


----------



## dengland (May 25, 2014)

Niick said:


> here are the pics of the midbass assemblies that I built for him. They house 9" Morel Elate midbass drivers. We decided to go with the grille from the Morel AdMW 9. You can kinda see in the pictures that the assemblies are bolted in from the rear.


That is some really nice work!


----------



## Babs (Jul 6, 2007)

subterFUSE said:


> Anyone know if the new USB HEC module will charge an iPhone?
> 
> 
> Sent from my iPhone using Tapatalk


If you're using the camera adapter (new one), it's got a separate charge-back lightning port. Plug that into a car charger in the console and keep on keepin' on.


----------



## Niick (Jun 3, 2015)

I got the confirmation today. I was told the truck with the Helix DSP filly active system, the one I did the midbass drivers in the doors, it will be dropped off for me Wednesday morning so that I can use it to make the video. 

The video shall be called "Measuring Phase In Cars.... and Other Stuff"


----------



## bnae38 (Oct 3, 2015)

Niick said:


> I got the confirmation today. I was told the truck with the Helix DSP filly active system, the one I did the midbass drivers in the doors, it will be dropped off for me Wednesday morning so that I can use it to make the video.
> 
> The video shall be called "Measuring Phase In Cars.... and Other Stuff"


:beerchug:


----------



## Niick (Jun 3, 2015)

I'm going to review the questions in the later part of this thread that pertain to the video, but if you or anybody thinks of anything else they'd like to see, let me know and I'll do my best to incorporate it. 

I have basically the whole day just to make this video, so I should be able to cover a fair bit of ground. 

Expect it to actually be uploaded either late Wednesday (tomorrow) night or early Thursday morning. 

This will be my first pre-planned video that goes into to real detail on tuning topics. So, in other words, it should be my best one so far. (that's a pretty low bar though! Ha!)


----------



## bnae38 (Oct 3, 2015)

No other thoughts on my end Nick. We appreciate it!


----------



## Niick (Jun 3, 2015)

https://youtu.be/4sUl20bN94M

This just shows me getting set up. Unfortunately I'm very limited on time, I am not going to have the vehicle for as long as I had hoped, but I'm recording as we speak, so wish me luck, I'll do my best.


----------



## Niick (Jun 3, 2015)

All right guys, that's it. I'm done. I'm EXTREMELY frustrated. I had relatively good lighting because I had all the lights in the shop off, it was miraculously slow in the first part of the day. But that didn't last, and now, with the lights on, you can't see the screens in the video. 

Plus, I only have the vehicle for a very limited amount of time. 

Making videos was a noble idea, but the logistics of actually pulling it off is simply not possible. I don't have e the equipment, the lighting, or the time. 

I apologize for letting you guys down, but I'm done. I quit. It's too much. 

I don't have the time, I don't have the equipment, I don't have the lighting. 

The preparation to successfully make a video that you all can see, and pull it off during business hours, is just not gonna happen. 

But I tried. BELIEVE ME, I tried. 

I did get some video though, and I suppose I'll at least post what I was able to get. It ain't much though. It ain't anything like I wanted. 

Man, I'm really regretting ever even attempting to try this now. 

Sorry everyone. I let you all down


----------



## bnae38 (Oct 3, 2015)

Niick said:


> All right guys, that's it. I'm done. I'm EXTREMELY frustrated. I had relatively good lighting because I had all the lights in the shop off, it was miraculously slow in the first part of the day. But that didn't last, and now, with the lights on, you can't see the screens in the video.
> 
> Plus, I only have the vehicle for a very limited amount of time.
> 
> ...


No worries Nick, we'll survive .


Thanks for attempting.


----------



## phil r (Sep 25, 2014)

forty5cal1911 said:


> Was really looking forward your phase demo Nick.
> 
> I know how it is Ben. I've been covered up with projects at work and haven't really had any time at all let alone for tuning.
> 
> ...


i have also been asking myself this question for a while.....would like to read some opinions....my only software is REW
thanks


----------



## bnae38 (Oct 3, 2015)

Welp.. the helix goes in tomorrow. Wish I had more info on proper phase measurement/how to use the phase control at xo for starters. Any thoughts?


----------



## brumledb (Feb 2, 2015)

bnae38 said:


> Welp.. the helix goes in tomorrow. Wish I had more info on proper phase measurement/how to use the phase control at xo for starters. Any thoughts?


There is lots of info on how to use REW to examine phase.

Go to post #4.

Setting Loopback Timing Reference Correctly - Home Theater Forum and Systems - HomeTheaterShack.com


----------



## bnae38 (Oct 3, 2015)

brumledb said:


> There is lots of info on how to use REW to examine phase.
> 
> Go to post #4.
> 
> Setting Loopback Timing Reference Correctly - Home Theater Forum and Systems - HomeTheaterShack.com


tyvm


----------



## bnae38 (Oct 3, 2015)

Apf is... pretty cool . Ditto for variable phase on each driver (same thing basically).

Am able to guess and check with good results for the most part. Measuring phase/predicting/applying correct apf's still not something I've really mastered but.. Fairly easy to see on the rta when things are working with summing response.

Digging this dsp.2. Couple glitches, nothing serious. One major setback was TA wasn't working early on using the measured setting. Don't really want to admit how long it took me to notice lol... a lot of my summing issues moved to different spots, was wondering wtf was going on.

Can switch it to ms and it still displays length too. Appears to be working properly set that way. Unknown if it was just a one time glitch, but i let Julian at AF know.


----------



## bnae38 (Oct 3, 2015)

I have one 2nd order q1.4 apf at 155hz(?) on the right midbass, fixed LR summing there. Also have midrange phase at 225deg on both, gets me good at xo as far as acoustic summing anyway..

I have a dip at about 600hz and a couple above in overall response. Can see why looking for 180deg points on phase plots. Playing with rew ap filters in generic eq.. From what i can extrapolate, they are 2nd order variable Q. But anyway, not sure where to go from here, open to suggestions .

Other stuffs: unwrapping is still my preferred way to view (i know wrapped is the ideal way to view but..). Ideally, does phase track with a constant slope for both sides? I still have a hump at XO (400hz), though they sum now. Also, do you guys typically view phase in linear or log scale? 


thx

Ps, not going to give phase much thought above... 1-1.5k probably.

Wrapped









Unwrapped


----------



## sqnut (Dec 24, 2009)

bnae38 said:


> Welp.. the helix goes in tomorrow. Wish I had more info on proper phase measurement/how to use the phase control at xo for starters. Any thoughts?


Phase angle calculation time delay frequency calculate phase lag time shift between voltage difference time of arrival ITD oscilloscope measure two signals formula angle current voltage phi phase shift time difference - sengpielaudio Sengpiel Berlin

Enter the xover frequency of the driver and the delay on the driver and it calculates the phase angle. Think of phase as fine tweaking your TA.


----------



## tonny (Dec 4, 2010)

I did play a bit around with the allpass filters in my Mosconi 8to12 dsp, the first thing I did was to get the left and right frequentie response the same with crossovers eq and time delay, get the delay right between left and right and then look how left and right add up together where they don't ad up right try and put 3 allpass filters in there so they add up right, this was a nice improvement which is doable with most measurement systems for example with Rew, I did use Fuzzmeasure as I find it more easy to use but it only works on a Mac.... 
The only problem with most measurement programs is that they can't measure the real acoustic phase! 

After this setting I used the same settings as above exept for the allpass filters and measured the real time phase with Smaart a different measurement program what can measure the real time phase response! Most off the allpass filters where in the good area but not 100% optimal, I could further fine tune the exact frequentie where the filter is added and also further fine tune the Q off the filter to get the left and right phase response as good as possible. I ended with only 2 allpass filters one around 800hz and one around 1700hz one less as the first option. 

I did compare both setting by ear and the second one was best! Even that one the frequentie measurements the left and right did cancel out each other around 10khz... 

Are there more people that did play with the allpass filters and how did you tune them?


----------



## bnae38 (Oct 3, 2015)

I tried using REW to estimate phase changes with apf and tried a handful of filters to get L and R sides to match, did not work (as expected sorta..). Hmm..


----------



## tonny (Dec 4, 2010)

bnae38 said:


> I tried using REW to estimate phase changes with apf and tried a handful of filters to get L and R sides to match, did not work (as expected sorta..). Hmm..


REW and most programs calculate the phase out off the frequentie response... 
That won't show the real phase that you are trying to adjust with the crossovers and allpass filters....


----------



## bnae38 (Oct 3, 2015)

tonny said:


> REW and most programs calculate the phase out off the frequentie response...
> That won't show the real phase that you are trying to adjust with the crossovers and allpass filters....



Measured phase seems to coincide with my cancellations I get between sides etc. Fairly sure it's measuring fine.

It's the predictions in rew eq using apfs that isn't always working the way I'd think.


----------



## bnae38 (Oct 3, 2015)

tonny said:


> I did play a bit around with the allpass filters in my Mosconi 8to12 dsp, the first thing I did was to get the left and right frequentie response the same with crossovers eq and time delay, get the delay right between left and right and then look how left and right add up together where they don't ad up right try and put 3 allpass filters in there so they add up right


Fwiw, I did all my driver to driver eq, xo's and ta first. Curious what you mean by 3 allpass filters?


----------



## Niick (Jun 3, 2015)

bnae38 said:


> Welp.. the helix goes in tomorrow. Wish I had more info on proper phase measurement/how to use the phase control at xo for starters. Any thoughts?


 So, I can tell you this. The basic concept can be explained with words. If you're adept at using measurement software, then the logistics of pulling off these basic concepts can be figured out.

So, contrary to popular belief, REW DOES measure the actual phase, it CAN calculate the phase based on the magnitude (this is what happens when you click "show minimum phase.... It does a Hilbert Transform of the magnitude to show the minimum phase response that such a system could, in theory, have). 

The logistical problem with performing phase alignments in REW is that after EACH AND EVERY sweep, you have to go in and manually set your reference delay (by clicking in the little gear in the upper corner of the IR window and inputting a previously arrived at time in ms) 

It is imperative that you use the same reference delay number for each measurement that you're attempting to align. 

Then, of course, you use the overlay window to compare each set of measurements and decide which one needs more or less delay/phase shift. 

An all pass filter IS NOTHING MORE than frequency dependent delay.

Finally, when comparing two traces to see which one needs adjusting, the slope of the phase trace shows you relative arrival time. The steeper the slope, the greater the delay. 

That's really it. match the slope of the traces, use polarity to get them to overlay, if necessary. 

a lot of this basic concept I was able to capture on video before the lighting went to ****. Unfortunately, I found myself explaining all of this stuff using Smaart and SysTune, then when I would try to show how you'd do it in REW, I'd get so lost in the logistics of trying to pull it off with REW that I'd loose my train of thought.... 

I'll take a look at the videos I did get today, because it sounds like some of it might actually still be of use to some folks.


----------



## bnae38 (Oct 3, 2015)

Hi nick, can you explain the reference delay a little more? Probably pretty basic stuff you you, but still getting a grip on it.

So let's say I do my left side only, using acoustic time delay, then compare to the right side only, again using acoustic time delay. These may not be in proper sync? 

Looking at my plots, they "seem" correct, but I might be wrong..

Threw a loopback with audio out together at work, I can try that too in rew using the other sync method. 

Fwiw, I'm using a usb umik, but I also have an imm6 analog Mic available that I used to use before the umik. Actually, very nice little Mic with cal etc. I had made my own trrs adapter/breakout cable with a switch for soundcard cal. Worked decent in the past.


----------



## bnae38 (Oct 3, 2015)

Bumping this up, anybody had a chance to play at all with apf?

I have not really.. but hopefully again this coming weekend.


----------



## oabeieo (Feb 22, 2015)

sqnut said:


> Phase angle calculation time delay frequency calculate phase lag time shift between voltage difference time of arrival ITD oscilloscope measure two signals formula angle current voltage phi phase shift time difference - sengpielaudio Sengpiel Berlin
> 
> Enter the xover frequency of the driver and the delay on the driver and it calculates the phase angle. Think of phase as fine tweaking your TA.



That's a pretty good calc sq thanks for sharing that.

I just recently learned how to calculate it on my own. 
The calc is good and works great! 

And to elaborate on this, the radians is the actual conversion 
I like how it converts radians to degrees for you. All in one go. Pretty nifty


This will also let you know how much phase difference is between left and right at any given frequency based on distance, which requires one more calc but everyone knows how to calculate PLD to ms. It doesn't (greatly) matter where phase is unless there's a second driver going against it or if there's radical time differences greater than 1/4cy 

At crossover is a good place to start, however I would focus more on somewhere before the 1st combfilter. If your right on top of the 1st comb directivity issues will make you spin your wheels and the dominant sound will surly cause issues especially in a 3way front. 

At crossover will just determine where the theoretical phase would be at crossover based on that frequency. And the sentiment is get alignment there and the rest will work its way on up the passband on its own....anechoicly sure . In car , maybe is totally on axis and very low reflections maybe some resemblance sure. But it doesn't quite work that way for most of us. 

So find where the combfilters are. 1 eq a test speaker to be stupid flat out in the back yard or somewhere non reflective. Put full range speaker in your speaker location and measure at listening position. You will see the frequency response has lots of peaks and nulls. That's the combfilter. The first null is the first comb. It will be somewhere past the Schroeder ( room modes) around 160-300hz depending on car and location. Where the responce peaks it's highest is constructive interference and usually is a artifact of horn loading and nulls are destructive interference and you'll notice it's in even intervals. 

So think of it like two different things happeng simultaneously. 

At some even frequencies there will be a horn loading condition and at some odd frequencies there will be cancellations (or vice versa). The goal is to find which frequencies that cancel when the other side speaker is turned on. So it's not by a reflection that's canceling the one side. 

You'll find that it is almost always around 250hz. 160-330hz depending on car width mostly. Using this calc can give you an idea on how it should be vs. how it's measured. Set your crossovers giving the speaker that cancels the least right past that null closest to desired crossover. If your speakers can't handle it get better speakers or go more on axis. Once you have gotten down to 2 combfilters measure phase difference right before the 1st comb and get both sides to be smooth with each other. Than and only than the rest will fall into place on its own. At least the best it can be with what ya got. seems the helix only has one phase shift per channel so that would be the best way that I can think of.

However all this can be done a hell of a lot easier with a good music track and your ears. 
If you can set your crossover around 160hz or use a nice low order filter on midrange around 200hz. Set time delays using standard tape measurements by ms. Than listen to good sq music and adjust the right side speaker phase until vocal is nicely centered between speakers. Done. Key is get that crossover below 200hz so most the interaction between drivers is all room mode zones. 


The more I think about trying to measure phase in car to adjust the one phase control is just silly for helix users. You'll spin your wheels to no end. 
Fir users ....go crazy with yourself ....you'll eventually get there and beat the odds just to find out at the end that dam null is the weakest link and there's no electrical fix for it. What I'm saying is if everyone wants to measure phase in car you have to first know where your combfilters are so your measurements don't play tricks on you. You eventually get the mic closer and closer and closer and closer to the speaker just to get a clean measurement. 

Once you know the acoustical behavior of your system it sure makes reading phase a lot easier. Especially when phase dives hard at 300 on one side and not at the other....


----------



## oabeieo (Feb 22, 2015)

Niick said:


> So, I can tell you this. The basic concept can be explained with words. If you're adept at using measurement software, then the logistics of pulling off these basic concepts can be figured out.
> 
> So, contrary to popular belief, REW DOES measure the actual phase, it CAN calculate the phase based on the magnitude (this is what happens when you click "show minimum phase.... It does a Hilbert Transform of the magnitude to show the minimum phase response that such a system could, in theory, have).
> 
> ...



Just tell everyone it's a big ole waste of time already unless your car is a convertible. 

I've spent way too much time on this just to discover what I already knew and it was completely pointless and my ears told me more than any one single APF and rew could ever say at measureable min phase frequencies in car. 

Once things become mixed phase it's a ****in disaster...seriously


----------



## oabeieo (Feb 22, 2015)

Think about what niick said sleep on it.

Negative phase is delay and positive phase phase means everything else is delayed. Casually speaking. (Don't get me started on casual vs. non casual filters that's a brain warp by itself) 

For no sound can move faster than the speed of sound so it has to mean just that. 

Than think about reading phase measurements in terms of just that. If something looks like it has positive phase it really means the measurement picked up reflections and or everything else is delayed. There always has to be a t=0 and if that is wrong in some parts and not others the measurements are dirty or something is coming out sooner than the t=0 which could be frequency dependent. Which is why frequency dependent windowing works. (To an extent)



Try measurements as close to speaker as possible. Set reference db 
Than move mic away raise amplitude to reference db and set t=0. Maintain reference db for power responce uniformity across measurements. 

Keep moving mic further and further keeping reference level and get rid of mic delay. 
Watch your measurements and you'll notice some very interesting time issues that are directly connected to your comb filters.


----------



## bnae38 (Oct 3, 2015)

Killin' my apf buzz O..



Thx for the thoughts


----------



## oabeieo (Feb 22, 2015)

bnae38 said:


> Killin' my apf buzz O..
> 
> 
> 
> Thx for the thoughts



Sorry  
The helix APF is the best way a APF can be implemented so don't feel discouraged, 

And I probably explained it a bit weird but should be mostly solid. 

Since I last posted in this thread I've been digging , and reading and experimenting.. I honestly was trying to beat niick to the punch but it was a lost cause.... I definitely learned quite a bit and rediscovered even more in a more fulfilling way.

Don't get me wrong please phase measurements have there uses. And I was truly mistaken by a small portion of what I said before in this thread. 

I've learned phase measurements are very tricky and truly require knowledge of what is happening acoustically with the room to interpret them correctly.

Rew does a fantastic job job at separating the mixed phase portions so you can put the puzzle together. It definitely had good use without any doubt , but for tuning a single phase adjustment on a single speaker your ears IMO can do far better job much much faster than dragging out all the mics and laptops and spending the time chasing the dragon over what....a 22° Phase offset.... at least in the midbass/lowmidrange 

I definitely understand the desire to read meaningful measurements as I strive to learn this **** as much as anyone else. The big issue is in a car things get nasty. Loading quarter space into half space is so problematic when it comes to a mic measurements. Once the measurement is posted on the screen it's so easy to interpret the measurements as empirical and it just doesn't quite work that easy. 

I'm not saying stop measurements and not saying it's a waste of time completely. I strongly encourage everyone to figure this stuff out. Hell I feel like I've just begun learning how to take usable measurements. Once I learned the mechanics of phase and how wavelength translates to radians it all started falling into place and all the features within rew are obvious why they do what they do and why the tools within it has to be done that way...

It's just the interpretation that I'm warning about. I can get a nice looking phase measurement with a simple gated window however is it correct????
That's where knowing what's happening acoustically at the mic location becomes huge brain damage. It's where your flat phase responce may not look flat and you adjust it till it's flat and it sounds worce or a certain element wasn't accounted for and made the measurement look that way when in fact it was probably correct from the get go.

Tape measure TA is pretty important when comparing two speakers phase between left and right. Weather it has a solid center image or not tape measure TA needs to be in place so at least its close and you can weed out the reflections from the measurements and get that glimpse of what's happening and truly discover why tape measure TA settings have or lack a solid center image...and combfilters are the reason tape measure TA wouldn't have the best center image. I bring up center because when phase is correct between sides the center comes into focus. If it were me I would do tape measure TA and use the APF as a focus lense like on a camera and nail down the center. All easily done by ear, and with a 1st order filter on midrange it makes the phase difference between midbass and midrange combine to make a new combfilter that helps overcome other combfilters....IME at least  


There's a way to get a usable measurement. It just takes some conciderations and a sober approach that's all


----------



## bnae38 (Oct 3, 2015)

I want 2 things to start with, solid transition from midbass to midrange, and to fix a cancellation at 170hz between midbasses. Those are the two reasons I'm in this thread and now own a helix. Both are a pita. 

I have the 170 issue "solved" already with an apf. Is it the best way to do it? Maybe.. Still learning.

As for the midbass to midrange transition, they sum correctly with either the midrange or midbass out of phase 180. Always been that way. Measure great that way. Sound goofy that way... hollow, off, etc..

Currently have the midrange at 225deg phase, best I could rough in.. Is it the best setting, surely not..

Anyway, if I can nail down these couple things, any capability beyond that is just a bonus.


----------



## oabeieo (Feb 22, 2015)

bnae38 said:


> I want 2 things to start with, solid transition from midbass to midrange, and to fix a cancellation at 170hz between midbasses. Those are the two reasons I'm in this thread and now own a helix. Both are a pita.
> 
> I have the 170 issue "solved" already with an apf. Is it the best way to do it? Maybe.. Still learning.
> 
> ...



What's happening at 170 a null or peak?


----------



## bnae38 (Oct 3, 2015)

It's a cancellation with both midbass playing, null in 170hz area.

Info here, was happy to see apf worked there 

http://www.diymobileaudio.com/forum...dbass-cancellation-options-angle-upwards.html


----------



## oabeieo (Feb 22, 2015)

bnae38 said:


> It's a cancellation with both midbass playing, null in 170hz area.
> 
> Info here, was happy to see apf worked there
> 
> http://www.diymobileaudio.com/forum...dbass-cancellation-options-angle-upwards.html



OKay so u mention the null shows up only when both speakers play against each other. So that's a destructive interference comb filter. So where is the peaks of comb? 200-300-600? Which bands do you turn down on your eq? 

But more than that which bands between 400-1.2k still sound too loud even when turned way way down? 


Sucks your comb is right at the very beginning of the combfilter range for a midbass passband.

I asked because said the APF would fix something that Low but would need another APF to set it back...which the helix didn't have. 

Any available channels left on helix that you can loop back into that driver and add another APF run on driver? Yeah adding a Ad/Da loop as well but **** it it would still be better than a nasty combissue. 

If you can do that at that low in the passband you should be able to set it back right after the null. You would be a wavelength off if you set it back by pulling phase back to 360deg and a very simple delay on other side could offset it back.

That would be one way.......however can you get the midrange to play down to 160? 

I would choose the driver that cancels the least from side to side and make that the dominant driver. That's where a 1st order filter could come into play... if the mid can't play down to 160 get a better driver that can...if it plays better...

I would let the suckout happen and don't eq everything else down to it, and use a 1st order filter on the midrange and let it fill in the gap...overlap in drivers in the 70-200hz range is preferred anyway and creates a array for best handling these nulls that happen below 250hz. 

If your mid isn't capable get one that is. Or move the speakers. 

The single APF function I personally wouldn't use on anything below 250hz . The single APF really should be used on the 250hz up range. If it even needs it (however I would suggest all cars would do better with a proper phase adjustment on mid if PLD is greater than about 6"). 

Here's the dealiio , the helix APF isn't really an APF like minidsp makes APFs. 
Helix moves phase of the entire band from crossover and up. A minidsp APF would move phase all the way to -180° At a rate depending on the Q of the filer. 

That's what makes the helix unique and it's better use of phase adjustment for a car but really should be used to correct a total offset not a single phase dip . 

So if you can loop back into it than you can cascade it and make it into something more like the mini version , able to correct phase at one spot in a pass band by cascading APFs....
And the only reason that even possibly work is because 160 would be the very end of the passband of the midbass. Otherwise cascading apfs would cause problems with the rest of the passband as far as timing goes. So if u did cascade APFs you would need extremely steep slopes on that driver to avoid crossover issues and a nice low order filter on midrange to make dominant and mask the delay caused by the crossover.


----------



## oabeieo (Feb 22, 2015)

And what's weird is all these phase measurements work better and better the lower you go below 250hz, so much so you almost don't even need to get rid of time to mic delay because everything is minimum phase at that point.


----------



## oabeieo (Feb 22, 2015)

You know bane , I tried some sims of what I told you last night and the times smear was horrendous, that cascading filters in that manner is not a good idea .

Especially in that phasey of an area . My bad was just thinking 



I would go back to the first order filter on the midrange and put your all pass filter on the mid range and not the midbass 

If you're using an optical in you could put a mini shark between those channels and create an F IR filter that would take care of it pretty freaking easy or you could use analog But that would be a lot of conversions...

Or do what I recommend in your thread , get a 10" or something and stick it in passenger footwell. Sealed box sub that can play to 200 with fidelity like a dyn or something of the sort
If you don't want to do that I would definitely get the sub woofer ,midbass and the mid range all to play 170hz , I would do that by using first order filters on the subwoofer and in the mid range , The sub woofer would barely have to give any power I would cross it over at like 50 or 60 Hz 6db , , and crossover the mid range around 250 Hz with the first-order filter as well that would big things act like an array in the Time smear would be largely in audible


----------



## bnae38 (Oct 3, 2015)

Lots to take in .

Thats what she said...


Anyway. I have my MR/MB crossed at 400hz atm. Both midranges dip at this point fairly hard so it just made more sense to do it there. 

I might play with working them lower again at some point, helps bring the stage up even more. But.... I do like having the extra cushion to crank the volume should i desire.

My phase tracks fairly well LR with the apf in place, see prior posts.


I'll be fully digging in again this weekend .


----------



## Souths1der (Aug 27, 2014)

Do you put the filter on the electronic crossover point, or the acoustic?


----------



## bnae38 (Oct 3, 2015)

Souths1der said:


> Do you put the filter on the electronic crossover point, or the acoustic?


Not sure what you mean?


----------



## Souths1der (Aug 27, 2014)

Well, I'm still a newbie in this world. Maybe I'm misunderstanding some things. I thought that the electrical and acoustic crossovers could be different. Meaning, if I had my Mids and Tweeters crossed over at 3kHz that would be my electrical crossover. But it's possible that my acoustic crossover when I do measurements could be something different.

In reading about APF's, it seems people mention to put an APF at the crossover point. I have no problem with trial and error, and listening for what sounds best. Just looking for the right starting point.


----------



## thebookfreak58 (Jun 18, 2012)

I too would like some guidance into how to apply/use an APF.

I get using the Jazzi tool and EQing to house curves.

I get using the tape measure to set the T/A.

But I am a bit unsure how to measure, read and use the phase stuff...


----------



## tonny (Dec 4, 2010)

Souths1der said:


> Well, I'm still a newbie in this world. Maybe I'm misunderstanding some things. I thought that the electrical and acoustic crossovers could be different. Meaning, if I had my Mids and Tweeters crossed over at 3kHz that would be my electrical crossover. But it's possible that my acoustic crossover when I do measurements could be something different.
> 
> In reading about APF's, it seems people mention to put an APF at the crossover point. I have no problem with trial and error, and listening for what sounds best. Just looking for the right starting point.


It is correct that the electrical and acoustical crossover will be different in most cases! And it's the acoustical output that counts, so always look at that. 

I my opinion if you get the crossovers and time delay right you don't need an allpass filters in the crossover area... I use them where left and right don't add up right together! You can do that by just measuring the frequentie response and see what it does, or if you want to make it even better measure the real time phase response and fine tune them with that.


----------



## oabeieo (Feb 22, 2015)

tonny said:


> It is correct that the electrical and acoustical crossover will be different in most cases! And it's the acoustical output that counts, so always look at that.
> 
> I my opinion if you get the crossovers and time delay right you don't need an allpass filters in the crossover area... I use them where left and right don't add up right together! You can do that by just measuring the frequentie response and see what it does, or if you want to make it even better measure the real time phase response and fine tune them with that.


How are you doing real time phase? 

I tryed and was wrong in my approach 

What software do you use 

Thanks


----------



## subterFUSE (Sep 21, 2009)

Real time phase can be done in Smaart or SysTune 


Sent from my iPhone using Tapatalk


----------



## bnae38 (Oct 3, 2015)

Smaart is stupid expensive, how about systune?


----------



## bnae38 (Oct 3, 2015)

Nm..


----------



## oabeieo (Feb 22, 2015)

subterFUSE said:


> Real time phase can be done in Smaart or SysTune
> 
> 
> Sent from my iPhone using Tapatalk



We know that silly  we've only been banging our heads on this for however long now LOL 

I was just asking him what he used out of curiosity


----------



## tonny (Dec 4, 2010)

oabeieo said:


> How are you doing real time phase?
> 
> I tryed and was wrong in my approach
> 
> ...



Most off my measurements I take with Fuzzmeasure, and sometimes REW. 
I did measure the phase with Smaart as that was the easiest way for me to do that.


----------



## sqnut (Dec 24, 2009)

My take on phase is pretty rudimentary, if I can't fix whatever sounds wrong with timing and response, I'm kinda wasting my time trying to fix it with tweaking the phase. The fact that we can't measure direct and reflected sound separately, and because 90% of what we hear in a car are reflections, phase coherence in a car is a bit of oxymoron. 

If I can't fix things with timing and response then trying to fix them with variable phase is like trying to have soup with a fork, keeps me busy but I stay hungry.


----------



## ErinH (Feb 14, 2007)

sqnut said:


> My take on phase is pretty rudimentary, if I can't fix whatever sounds wrong with timing and response, I'm kinda wasting my time trying to fix it with tweaking the phase. The fact that we can't measure direct and reflected sound separately, and because 90% of what we hear in a car are reflections, phase coherence in a car is a bit of oxymoron.
> 
> If I can't fix things with timing and response then trying to fix them with variable phase is *like* trying to have soup with a fork, keeps me busy but I stay hungry.


"like", implying you don't have the means to try so you don't know. Let me say from experience, then: you are missing out.


----------



## oabeieo (Feb 22, 2015)

tonny said:


> Most off my measurements I take with Fuzzmeasure, and sometimes REW.
> I did measure the phase with Smaart as that was the easiest way for me to do that.



Fuzzmeasure ....never heard of it. I'll check it out thanks


----------



## bnae38 (Oct 3, 2015)

That's a little more reasonable price-wise. What are your thoughts on fuzzmeasure tonny?


----------



## bnae38 (Oct 3, 2015)

Wait a min... mac only?


----------



## tonny (Dec 4, 2010)

bnae38 said:


> Wait a min... mac only?



indeed mac only....


----------



## sqnut (Dec 24, 2009)

ErinH said:


> "like", implying you don't have the means to try so you don't know. Let me say from experience, then: you are missing out.


Looks like you misread both the content and context of my post :shrug:


----------



## bnae38 (Oct 3, 2015)

Realized I can use a 30 day trial of systune for free. 

Duh..


----------



## brumledb (Feb 2, 2015)

I have Smaart7 and eventually I am going to figure out how to use it to align phase. I have read the manuals (more than once) and it seems simple enough but the couple of times I have tried to use it I could not get good results. But I just reread a lot of the manual and it makes more sense now. Maybe the next time I try I will finally succeed.


----------



## oabeieo (Feb 22, 2015)

bnae38 said:


> Realized I can use a 30 day trial of systune for free.
> 
> Duh..



We'll get to work dammit ! 
Lol 

Get us some red meat


----------



## bnae38 (Oct 3, 2015)

oabeieo said:


> We'll get to work dammit !
> Lol
> 
> Get us some red meat


Wish I'd noticed that earlier in the weekend.. 

I'll dl and start playing tomorrow.


----------



## bnae38 (Oct 3, 2015)

Well i've got the trial, will probably play tomorrow.

No cal file input for the umik, kinda disappointing.

Looks like smaart supports that, but i cant find a trial download for that....

Question: with systune, i'm not really sure about my delay offset setting. Running on the desktop speakers at the moment a bit..

Using the auto button for delay offset results in an ever-increasing offset and phase trace shifting left to right over time. When I'm in the car and place the mic stationary at the headrest and play PN, should i just hit the peak button to cal offset for the left side and ditto for right side before hoping to get meaningful measurements?


----------



## Niick (Jun 3, 2015)

bnae38 said:


> Well i've got the trial, will probably play tomorrow.
> 
> No cal file input for the umik, kinda disappointing.
> 
> ...


the reason the systune folks didn't put mic Cal file support on the list of important things, is because with sound system tuning, of any kind, even a measurement mic of moderate quality is FAR flat enough to use for sound system tuning and alignment. 

I used to go to great lengths to use the normalization plug in within systune to offset my measurement mic response from the measured data. Then I realized, it makes absolutely no difference to the end result. Dont sweat mic Cal files. It's really not as critical as people think. 

The reason your computer desktop speakers are resulting in an ever shifting phase trace (watch the live IR, it will illuminate the concept as well) is because either as a result of the drivers or the hardware, ultimately what is going in is that the A to D feeding mic signal to systune and the D to A feeding sound to your speakers are not clock synchronous. 

If you're using a USB mic, you simply cannot do live, real time IR/phase. This type of measurement system relies on the A to D and D to A sharing the same sample clock, or at least having a master clock signal that they both share. You must use a hardware audio interface and XLR mic to be able to make ultimate use of software like systune and Smaart.

EDIT: Sorry I missed that last part. So, assuming you have a clock synchronous A to D and D to A, then as far as using the "peak" button , this simply finds the part of the IR that is at the highest amplitude, which, more often than not, in a car, is not the initial arrival. the "peak" button can be used to get your reference delay close, but what you want to do is simply observe the IR, and manually use the delay spinners to increment the IR to the initial arrival. In systune, be sure to check "wrap at half length". this puts time zero in the middle of the graph, instead of the far left.


----------



## bnae38 (Oct 3, 2015)

I have an imm6 rig i used to use (all analog). I suppose i can give that a shot for this?


Thanks Nick!


----------



## bnae38 (Oct 3, 2015)

Where do i find "wrap at half length"?

Edit (in IR). got it..


Edit 2: forgive my noobishness, but why view IR? I planned on viewing phase in one window and magnitude in the other.


----------



## Niick (Jun 3, 2015)

bnae38 said:


> Where do i find "wrap at half length"?
> 
> Edit (in IR). got it..
> 
> ...


why view the IR???!!! 

WHY VIEW THE IR???!!!!!! 

 NO, Just kiddin.  

But seriously, EVERYTHING is contained within the IR. I ALWAYS look at the IR first to see where in time is my signal arriving relative to my reference, and (with saved overlays) relative to other signals. 

Also, the IR is an immediate indicator of signal polarity. Yes, phase can also indicate polarity, but above a few hundred hertz, in a car, reading the phase is far from easy. Sometimes it's far from possible.

So ya got immediate indication of polarity, timing, and last but not least, measurement signal quality/correlation. The IR/ETC will immediately make evident any noise in the measure OR reference signal. Poor signal to noise causes a "noisy" looking IR.

Having the freedom to take time domain measurements in real time, like with SysTune, is a completely different paradigm than taking static traces like in REW. The methodology and work flow is drastically different with SysTune. This ability opens up whole new possibilities. Things that would have never even been conceived of with REW. 

Keep plugging away at it.


----------



## bnae38 (Oct 3, 2015)

Didn't get a chance to play today.. 

I need to make the most of the 30 day trial, I know.. 

Soooon.


----------



## bnae38 (Oct 3, 2015)

Any new cost effective developments in measuring real time phase?

Been awhile since I've played with that and obviously my trial versions for smaart or systune have long expired. I'm guessing John M isn't going there on rew..

Not something i'm too concerned about measuring again, would just be interesting to view that kind of data when the mood arises


----------



## Babs (Jul 6, 2007)

bnae38 said:


> Any new cost effective developments in measuring real time phase?
> 
> 
> 
> ...



The only one I know of besides Room EQ Wizard, which is free, is Transfer Function in AudioTools for iOS. But it’s resolution for phase is nowhere as good as Smaart or Systune down in lower frequencies. Gets very notchy. But it does work. So while REW has much better resolution, it’s sweep-generated and not real-time. Transfer Function in AudioTools is real-time with pink noise generator. 


Sent from my iPhone using Tapatalk Pro


----------

