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phac can’t adjust anything automatically for the environment, so your left adjusting manually regardless
Same with Helix.
Look... i don't use PhaC myself most of the times. But all PhaC does in the end is set a 1st or 2nd order allpass filter with a frequency and in case of 2nd order a bandwith just like the variable phase slider in the Helix software does.
With Helix you move the slider and it automatically calculates the resulting allpass filter, frequency and bandwith, PhaC does the same, you move a slider and it automatically calculates the resulting allpass filter, frequency and bandwith for a frequency that you define. Only difference is, that Helix does this in 5.something degree steps and PhaC in 1 degree steps.
I already agreed with you that you should do that with some other software like Smaart or similar tools to minimize the amount of time needed, because you can see the result in the measurement software.
cathul said:
When watching it in real time in Smaart this is a real good way to set the phase as desired in a very quick way. Way quicker than typing in different allpass filters with bandwiths and stuff like that.
So PhaC can work if you use it a bit outside of the workflow as intended by Frank Miketta.
So i don't get it why you're arguing with me now.
 

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And this is why I made this guide - for people without trained ear.
Without 10 years experience.
Now they can make it too…
But as dumdum and I both said, you are "correcting" based on the electrical signal, which may not be correct acoustically.
 
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Same with Helix.
Look... i don't use PhaC myself most of the times. But all PhaC does in the end is set a 1st or 2nd order allpass filter with a frequency and in case of 2nd order a bandwith just like the variable phase slider in the Helix software does.
With Helix you move the slider and it automatically calculates the resulting allpass filter, frequency and bandwith, PhaC does the same, you move a slider and it automatically calculates the resulting allpass filter, frequency and bandwith for a frequency that you define. Only difference is, that Helix does this in 5.something degree steps and PhaC in 1 degree steps.
I already agreed with you that you should do that with some other software like Smaart or similar tools to minimize the amount of time needed, because you can see the result in the measurement software.

So i don't get it why you're arguing with me now.
I’m saying you can’t use phac alone as it’s pointless… the original post is about this.

phac is an automated system used for ‘correcting’ the phase response based on filters applied not a phase slider like in the helix, it’s a process that doesn’t work in a real world environment, I can’t say that I use the phase slider in helix either… occasionally I will apply an all pass filter, but that’s it as far as phase manipulation goes

the original post is about using phac with other dsps, not smaart. Most people don’t have smaart so phac is pretty much useless for me
 

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Well, PhaC is taking into account all the phase shifts from crossovers and driver filters, which the phase slider in Helix doesn’t. In this way PhaC might be more accurate after all. And as the OP outlined you need to transfer everything from the Mosconi to the Helix (or vice versa) to get accurate results, didn’t he?
 

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Discussion Starter · #26 ·
But as dumdum and I both said, you are "correcting" based on the electrical signal, which may not be correct acoustically.
I heared that and I’ve answered to that already, check my comments…
 

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1. it works for me... and all my people i know with Mosconi like the phac u can try it out.
it fix the phase shift made of the crossover and eq, plus it helps with the group delay so the result should be better sound stage.

2. I forgot about it i will check it but i don't think it will help u anyways.

Edit:
Checked it and it is not possible though the helix allpass display.

A demo of how it works with smaart:
it does not !!! Fix phase from crossovers , it’s makes them worse

If you need a sim , I’ll prove it.
 

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Discussion Starter · #29 ·
Admins can u delete this thread?
Seems nobody try it and everybody sure that it is not working without trying…
So if it isn’t helpful delete it.
 

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Admins can u delete this thread?
Seems nobody try it and everybody sure that it is not working without trying…
So if it isn’t helpful delete it.
Sorry if you felt like that some of us were being condescending, we did not mean it like that at least I can’t speak for everybody but I didn’t.

around here there’s some very respected names in car audio sound quality. and these are the exact issues that ruffle some peoples feathers because you have engineers that are good engineers but they’re not audio people.

it’s cool to develop a product that can do something, but when it’s counterproductive to our end goals it sure makes trying to help people hard when theremoving backwards instead of forwards

APFs have uses , but not like that. The problem is it can make the passband have a good phase, but the stop band is a catastrophe.

and that’s the part I think the engineers break down and don’t realize that almost everything that we hear is a mix of all the speakers playing.

so when you have detrimental timing discrepancies in the interaction areas there’s no way to come back from that…

And then you hear these catchphrases like, all past filters fix crossover phase twist. Which is actually the exact opposite of what they do, they add more phase twist. They simply move in the wrong direction.

All passes are a good tool to have, just not for this…

so again sorry if you felt like your contribution was under attack, It’s not you it’s the premise and the idea of these bells and whistles that are put in the products that doesn’t work.
 

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Frank of Mosconi knows exactly what hes doing. That said, I just don't exactly see a point in doing this. Crossovers work properly when used as intended and implemented correctly. No need to correct phase for a tweeter down to 100hz lol
 
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Frank of Mosconi knows exactly what hes doing. That said, I just don't exactly see a point in doing this. Crossovers work properly when used as intended and implemented correctly. No need to correct phase for a tweeter down to 100hz lol
It doesn’t as far as I know, it adjusts the freqs at the top end of the cover by x amount of degrees, if the other end of the all pass filter effects the lower freqs that’s a side effect of the phase shift being tiny, the helix phase shift does the exact same in reality, uses a second order all pass filter

However it still doesn’t change the facts we’ve both mentioned in that it doesn’t take into account any phase shift induced by the vehicle so may improve things or make it worse

the only time it can be handy is if you have two crossovers on a narrow band with driver as they interact and change the phase by more than if they were spaced apart, but again this assumes the driver has perfectly flat phase in the first place

you can model this in jl tun’s newest release or see it also on the helix software if you turn the all pass filters on 👍🏼
 

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These discussions always confuse me. Any guidance is appreciated -

If I have two mid-ranges, and they both have proper response, but when played together create a dip, I can play around with an AP filter and try to fix that dip ?
This is what I do now but its all guesswork, I just play around with a 1st or 2nd order (and inverted or not) AP of different frequencies on one channel until I get better summation and no weirdness elsewhere (and I always follow that up later with a listening test where I turn it on and off).
I understand I can see in Helix what the phase plot is doing when I do this but that it probably won't match what's actually happening in the car.

And moving the phase slider up is moving a 2nd order AP filter up in frequency from the crossover point (unless its the subwoofer channel when you are moving down in frequency, and the phase slider doesn't do anything on the woofer channels)

Is that more or less correct ?

Where it gets complicated to me is if you've aligned phase between two mids, and now you bring in the woofers or mids. I can use the same trick in the x-over regions to match ie improve the summation between those 2 drivers. But if I apply an AP (or phase slider) between a mid and a woofer, I have now potentially messed up the phase between the mid's again.

Skizer I've heard you say you don't feel like you need a tool like Smaart that you can do it just using REW and summation.
I've never really learned how to use or understand the phase plots in REW and don't know if they're useful or if I need a loopback or more than my Umik-1 to use them.
 

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Skizer I've heard you say you don't feel like you need a tool like Smaart that you can do it just using REW and summation.
I've never really learned how to use or understand the phase plots in REW and don't know if they're useful or if I need a loopback or more than my Umik-1 to use them.
Agreed - this would be good to know.
Dave
 

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These discussions always confuse me. Any guidance is appreciated -

If I have two mid-ranges, and they both have proper response, but when played together create a dip, I can play around with an AP filter and try to fix that dip ?
This is what I do now but its all guesswork, I just play around with a 1st or 2nd order (and inverted or not) AP of different frequencies on one channel until I get better summation and no weirdness elsewhere (and I always follow that up later with a listening test where I turn it on and off).
I understand I can see in Helix what the phase plot is doing when I do this but that it probably won't match what's actually happening in the car.

And moving the phase slider up is moving a 2nd order AP filter up in frequency from the crossover point (unless its the subwoofer channel when you are moving down in frequency, and the phase slider doesn't do anything on the woofer channels)

Is that more or less correct ?

Where it gets complicated to me is if you've aligned phase between two mids, and now you bring in the woofers or mids. I can use the same trick in the x-over regions to match ie improve the summation between those 2 drivers. But if I apply an AP (or phase slider) between a mid and a woofer, I have now potentially messed up the phase between the mid's again.

Skizer I've heard you say you don't feel like you need a tool like Smaart that you can do it just using REW and summation.
I've never really learned how to use or understand the phase plots in REW and don't know if they're useful or if I need a loopback or more than my Umik-1 to use them.
except the part your asking skizr something ,

if there’s a dip and an allpass helps fill the dip that’s only fixing a frequency responce issue

the problem is the time domain is corrupted. It no longer is in time with everything else especially the other side speaker

without Dirac or an fir that has arbitrary phase correction that can solve the real issue and keep a clean impulse , then it’s pointless and it’s better to just ignore the dip.

Just because the mic shows a dip don’t mean you have to try and fix it, the energy is still there.
 

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So how/when would you apply an AP filter ?
I've read some of your tuning posts and they usually leave me baffled so keep it simple :)
 

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So how/when would you apply an AP filter ?
I've read some of your tuning posts and they usually leave me baffled so keep it simple :)
You can do it in situations as you have mentioned, but you really need to verify that what you are doing isn't just filling a hole in the response. Make sure it is actually making a positive change to what you are hearing. Is that frequency range smeared? If so, did it snap into place? you can also use them to phase-align speakers through crossovers.
 
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APFs have uses , but not like that. The problem is it can make the passband have a good phase, but the stop band is a catastrophe.
and that’s the part I think the engineers break down and don’t realize that almost everything that we hear is a mix of all the speakers playing.

so when you have detrimental timing discrepancies in the interaction areas there’s no way to come back from that…

And then you hear these catchphrases like, all past filters fix crossover phase twist. Which is actually the exact opposite of what they do, they add more phase twist. They simply move in the wrong direction.

All passes are a good tool to have, just not for this…
If you talk to Frank Miketta about the theory it totally makes sense to use a tool like PhaC or the Helix phase control for exactly this purpose.
From the workflow point of view with PhaC you are correcting phase differences that are caused by crossovers through the different slopes, especially with odd order crossovers and driver specific filters that all have an effect on phase after you have done the time alignment, and you do the PhaC on both side drivers, not only on one driver, and you do the PhaC on the crossover freqency, not an arbritary frequency that you see fit.
As allpass filters cause a frequency dependant delay they actually can work under these circumstances as you f.e. usually need to delay the highpassed speakers due to the phase shift caused by crossover slopes.
But again, it only works correctly if you're doing the time alignment as the very first step before setting driver specific filters including crossovers.

Problem is, you always have to measure if you really have an actual problem in this area after the car messed around with the acoustical phase due to all the reflections and stuff like that.

I personally listened to cars where the PhaC worked like expected and intended, but i also heared my own car where it didn't really work as expected and intended.
 

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However it still doesn’t change the facts we’ve both mentioned in that it doesn’t take into account any phase shift induced by the vehicle so may improve things or make it worse
One question (well, actually it's more than one...). Isn't this phase shift of the cars acoustics done to all drivers at the same time? F.e. in the area where you pass over the duty from midrange to tweeter?
If yes, the relative phase would stay the same even due to the induced phase shift by the car, right?
In this case, an allpass filter as created by either PhaC or the Helix phase control would still work as intended.
 
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