You can center the impulse where you want in rephase
That should be used to target the frequencies your fir is running before using optimization.
Although, I’ve had a small ripple in the phase on a fir I made once where minimal optimization fixed it and only put my like 1 degree away from flat/target. It was a trade off I found to be worth it at that time using a low tap filter
Pos had mentioned whatever is generated in red is actually what the filter will do.
For me is about using all the tools at hand to make it work the best and for me as long as it’s following my target to about -30db I’ll use it....
A bunch of stop band ripples in the -80db area don’t bother me
GD is an artifact of excess phase if I remember correctly. Meaning, if you input a measurement that has excess phase in it , instead of measured phase, and you make flat the areas you can without degradation (takes experience and common sense) the end result will be removed GD. The step will be better and the system will rise quickly.
As far as very high Q GD peaks go, I’ve tried and it takes an outrageous amount of taps to get those and I didn’t really notice much of a difference, maybe 1 or 2 in the 250-1k area might (maybe) help, I mostly just leave those alone as it’s most likely a compound reflection or a comb filter that is an install issue (locations, environment,enclosure etc)
I probably said that wrong somehow and feel free to correct me, but I think what I am trying to say is there.
As far as frequencies below 100hz, I can’t tell you too much as I don’t use ported boxes so GD for me is almost non existent, but there is a GD removal tool for ported boxes in rephase. I would imagine it works nice. Would need some outside measurements tho. I can’t speak to how boundary interference plays into that.
I also wanted a GD graph a while ago, and yeah it would help, I’ve just been discovering low Q (under 5) phase eq in the 100-1k range is all I can do without making it worse or making it sound wrong or have detrimental problems in imaging. I’ve completely stopped using phase eq above 1.6k and below 100hz
Eq does the trick as , again, it’s a measurement or Install issue that can’t be fixed with measurements.
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Question for pos.
Hi POS,
when you introduced your rePhase, you inquired about the possibility of correcting phase in bass reflex enclosure.
I have not finished reading the entire - 345 and counting pages - thread yet, so I do not know if you reported on your results, hence my question.
Kindest regards,
M
Hi POS,
when you introduced your rePhase, you inquired about the possibility of correcting phase in bass reflex enclosure.
I have not finished reading the entire - 345 and counting pages - thread yet, so I do not know if you reported on your results, hence my question.
Kindest regards,
M
I’m certain a corrected BR will sound better then non corrected. I mean , who wants that outrageous amount of delay from half of the bass response.
With that said , it’s not going to do squat about transient response, which BR is pretty bad at.
But for the most part , it can make cherry pie out of dog s*it
With that said , it’s not going to do squat about transient response, which BR is pretty bad at.
But for the most part , it can make cherry pie out of dog s*it
Group Delay is defined as the negative derivative (or slope) of the phase response vs. frequency.
A few links to refresh your memory
http://www.cjs-labs.com/sitebuildercontent/sitebuilderfiles/GroupDelay.pdf
Group Delay Graph
Minimum Phase
It is a matter of preference really. My personal experience is limited with BR corrections, just because I don't have the luxury of having that many taps in my system.
Yes it does: that transient response is minimum-phase.
Okay in an acoustical way , a resounding yes..... but a mechanical improvement as well? I’m thinking how a sub behaves in BR. Low Q sub for obvious reasons will be more versatile as far as transient response.
Aaahhhh yes that is what I was trying to say. I knew it was connected , and I did need a brush up thank you.
Since a BR is acting the same way, there is nothing stopping you of tuning a cabinet with a Q of 0.5 or so.
In that way one can get exactly the same response as a LT sub with an highpass filter.
(Not using any HP filter on LT is kind of stupid and asking for trouble.)
From a control theory point of view, those systems will be 100% identical.
Obviously both systems have their own advantages and disadvantages when it comes down to non-linear behavior as well as practical considerations for different reasons.
But that's inherent to the properties of those systems.
Hi pos,
thank you for the reply.
I understand that it is a matter of personal taste, so let me rephrase my inartfull language: Did the correction fulfill your expectations?
Hi b-force,
Could you please clarify this, perhaps in a p.m., so that we do not pollute this - already polluted - thread by OT issues?
Kindest regards,
M
thank you for the reply.
I understand that it is a matter of personal taste, so let me rephrase my inartfull language: Did the correction fulfill your expectations?
Hi b-force,
Could you please clarify this, perhaps in a p.m., so that we do not pollute this - already polluted - thread by OT issues?
Kindest regards,
M
Better to maybe open a separate new topic, because I think more people would like to know, otherwise just PM me.
Not sure what you mean here. Transient response is in the magnitude/phase response.
Compared to a sealed alignment BR will reduce driver excursion above the tuning frequency and increase it under it. That is about the only difference that remains once you turn both of them into a given filter using FIR (with a final slope of at least 24dB/oct of course).
You can for example use a BR alignment for a midbass driver, with a high tuning frequency (around crossover frequency) that will result in a large bump in its response. Once you compensate for all this in the FIR to build a crossover with a steep-ish slope (eg 48dB/oct) you end up with a system that behaves exactly like if you had build that same response upon a sealed midbass, but with much lower excursion in the lower range. That typically let you lower the crossover frequency, and/or use a driver with a lower excursion and higher efficiency.
That can be a good trade-off, but is more difficult to build than a sealed system (eg avoiding resonances of the tuning port in the passband), and can also be less "stable" than a sealed system. The higher the Q the more sensitive the response will be to system variations such as temperature (from the room, or from signal in the VC), manufacturing consistency, amplifier output impedance or suspension aging.
It was certainly audible with the right tracks and SPL, but not necessarily subjectively "better". Bass was sometimes "tighter", but then the balance was also different. There is a case to be made that regardless of the speakers used during production (number of ways, crossover frequencies and slopes, etc), virtually none of them are phase linear down low. So artistic decisions (levels, EQ, timing) do take that into account.
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