This weekend I was playing around with my system, creating an active 3 way + sub system using Transient Perfect loudspeaker DSP tools . Windows DSP speaker crossovers. Frequency Allocator crossover program. I managed to get a nice configuration then I made a "mistake." I switched on the Arbitrator, which uses some form of magic to make the crossovers transient perfect. Now I have to have transient perfect crossovers. The problem is that Allocator/Arbitrator require processing time and the delay messes up lip synch in my multi purpose music/HT system. If I fix the mains the surrounds are early, not a good effect.
While I have an engineering degree and had a fair amount of calculus, it was a long time ago and has not been used in decades. I can still handle basic calculus, but that's about it. Can anyone suggest some reading/self learning to get me up to speed on the math needed to understand and design transient perfect crossovers? I will go active, having plenty of quality amplifiers. In the past I just plugged the equations Linkwitz provided into a spreadsheet. Once you get into imaginary numbers my ability to create a spreadsheet formula gets left behind.
My main problem is I don't know where to start learning. Thanks in advance for your help.
While I have an engineering degree and had a fair amount of calculus, it was a long time ago and has not been used in decades. I can still handle basic calculus, but that's about it. Can anyone suggest some reading/self learning to get me up to speed on the math needed to understand and design transient perfect crossovers? I will go active, having plenty of quality amplifiers. In the past I just plugged the equations Linkwitz provided into a spreadsheet. Once you get into imaginary numbers my ability to create a spreadsheet formula gets left behind.
My main problem is I don't know where to start learning. Thanks in advance for your help.
Bob,
Down load the manual tot he Ultimate Equlaizer. I wrote the section on "How Does it Work". It's a different approach than what you are using since it is all FIR based. But the developer has continued to refine the code and the convolution engine to get latency down. I should be well with in acceptable limits for video sync.
web page: Bodzio Software
Manual PDF: http://www.bodziosoftware.com.au/Ultimate_Equalizer_Manual_5.pdf
P.S. If you consider each speaker which a conventional crossover as a "driver" in the UE, you can use the UE just to linearize phase of those existing speakers so a 5.1 system can be done with a total of 6 channels.
Down load the manual tot he Ultimate Equlaizer. I wrote the section on "How Does it Work". It's a different approach than what you are using since it is all FIR based. But the developer has continued to refine the code and the convolution engine to get latency down. I should be well with in acceptable limits for video sync.
web page: Bodzio Software
Manual PDF: http://www.bodziosoftware.com.au/Ultimate_Equalizer_Manual_5.pdf
P.S. If you consider each speaker which a conventional crossover as a "driver" in the UE, you can use the UE just to linearize phase of those existing speakers so a 5.1 system can be done with a total of 6 channels.
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Transient perfect or flat phase response crossovers require more delay the lower in frequency they are flat in phase, so for the short delay times required for video sync or live use you have to limit how low you need the phase to be flat.
There were several responses to my question in post #525
http://www.diyaudio.com/forums/mult...e-linearization-eq-fir-filtering-tool-53.html
that may help your understanding, #535, #544 go in to some specifics.
I'm sure there are different approaches to making transient perfect or flat phase response crossovers, but unfortunately there is no way to accomplish the goal in real time using a multi-way system, so video delay (and surround delay) will be necessary to perfect your system.
Art
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Bob, as others have mentioned, you may be interested in a FIR filter based solution, such as: Advanced Acourate Digital XO Time Alignment Driver Linearization Walkthrough Note the Digital XO section and the reference to: Thoughts on XO's.
Used in conjunction with JRiver's Media Center's 64 bit Convolution engine, which takes into account the FIR filter delay (even with a 65,536 tap linear phase filter) there are no video sync issues.
Hope that helps.
Mitch
Used in conjunction with JRiver's Media Center's 64 bit Convolution engine, which takes into account the FIR filter delay (even with a 65,536 tap linear phase filter) there are no video sync issues.
Hope that helps.
Mitch
Thanks for the responses. I was thinking I needed a few math courses, and try to make it all analog but you've got me going a different direction.
John K, looking at the hardware requirements, I'm glad I built an overkill computer.
Art, thanks for the information.
Mitch, I'll have to really study that, since I already use JRiver.
Whichever solution clicks in my brain first will probably be the way I go.
John K, looking at the hardware requirements, I'm glad I built an overkill computer.
Art, thanks for the information.
Mitch, I'll have to really study that, since I already use JRiver.
Whichever solution clicks in my brain first will probably be the way I go.
Hi Bob,
Actually, depending on what you want to do the computer requirements are not that bad. I have a W7 machine with 2.7 GHz processor and 2G ram and a single Delta 1010LT sound card and I can easily run anything that the sound card can handle. For example, if you have an existing 5.1 system using passive crossover speakers (or for that matter active crossovers) you can use the 6x1 option. That means basically you have 6 1-way speakers. As I said before, if you consider each speaker as a "driver" you can use the UE equalize the response of each speaker to your desired target and linearize phase as well. This just requires that you measure each speaker over it's full range. Then the amplitude and phase of the speakers, (including crossover induced phase shifts) is imported into the UE as a "driver". You end up with 6 inputs, one for each 5.1 channel, including the sub, and 6 outputs. which correct amplitude and phase of each speaker, again, including the sub. You can also add room eq for the sub if you like.
Now, if you want to go with active speakers and use the UE/CP as the crossover you need more computing power and dual sound cards and it get's messy, not to mention all the requires amps.
In other words, you can use the UE as a full blown multichannel active crossover with phase linearization. Or you can use it as a multichannel amplitude/phase correction equalizer. Another feature that is nice is that phase linearization can be turned on or off which means you can isolate the audible effects of phase linearization.
And the nice part is that you don't have to dick around with assembling pieces. The convolution engine is built in and it includes a measurement system as well. So, given that you have the hardware, (PC, sound card, mic, mic preamp) it basically plug and play.
Thanks, John. I hadn't thought of using the each speaker as a driver in UE for and then only needing the 8 outputs. I could theoretically do that with Frequency Allocator/Abritrator running multiple instances. UE sounds a lot easier. Mitch's article is starting to sink in, too.
I have an M-Audio Fire-wire 410 with enough outputs, but it doesn't allow software routing that would allow me to get the surround channels into Allocator/Arbitrator. It looks like M-Audio is still working on the Delta 1010LT replacement even though they have discontinued production of the Delta 1010 series. They did that with the FW410, it was unavailable for months before the FW610 appeared. Any suggestions for a suitable card under $500?
I have an M-Audio Fire-wire 410 with enough outputs, but it doesn't allow software routing that would allow me to get the surround channels into Allocator/Arbitrator. It looks like M-Audio is still working on the Delta 1010LT replacement even though they have discontinued production of the Delta 1010 series. They did that with the FW410, it was unavailable for months before the FW610 appeared. Any suggestions for a suitable card under $500?
Don't know off hand Bob. Also, I forgot that I am running the UE V4. I got out of the loop after that. UE5 requires a multi-core processor. My bad for not remembering that.
I would suggest that you contact the developer for sound card and minimum PC requirements for UE5. Bohdan's email is at the bottom of his web page. Tell him Kreskovsky sent you.
If you want to have the whole system transient perfect from the lower cutoff up to the upper cutoff frequency then there is no way around large latency.
If you just want to make your crossover transient-"perfect" you may as well use some signal processor like ADI's sigma DSP and the latency caused by this wouldn't be too great either.
Regards
Charles
If you just want to make your crossover transient-"perfect" you may as well use some signal processor like ADI's sigma DSP and the latency caused by this wouldn't be too great either.
Regards
Charles
My Oppo BDP-103 will allow me to correct lip synch with Allocator/Arbitrator. The issue I have is using a TP filter on the main channels and not on the center/surrounds so I have differing lip synch requirements.
The easiest solution seems to be get a sound card or two with enough inputs and outputs to allow me to run all channels on Allocator and then all are at the same delay. A check engine light on my car as inspection is due just put a serious dent in my progress towards that goal. For now TP is limited to 2 channel music.
The easiest solution seems to be get a sound card or two with enough inputs and outputs to allow me to run all channels on Allocator and then all are at the same delay. A check engine light on my car as inspection is due just put a serious dent in my progress towards that goal.
For now TP is limited to 2 channel music.As already said - it depends on how far you'd like to go with "transient perfect". If it is just for the crossover frequencies of a three-way system, the delays caused by a such a crossover aren't large and would probably not be noticed at all. If you want to cross a subwoofer at 80 Hz in tansient-perfect fashion you will have quite a large delay (in the area of 10 ms). If you want to have your woofer rolloff in transient perfect fashion as well you will end up with much more delay than that.
Be aware that there are also latency-free possibilities for transient-perfect crossovers but these are more demanding on the drivers.
Regards
Charles
Be aware that there are also latency-free possibilities for transient-perfect crossovers but these are more demanding on the drivers.
Regards
Charles
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