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Why do we need Xovers (anymore)?

adLuke

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Hi all,
I am reading a bit about sound basics for personal interest, so have lots of questions.
Reading about the crossovers (passive mainly, but some about active as well) there seems to be a great complexity and the designs seem really difficult by the Experts own admission.
My forecast (worthless of course)is that we'll be moving more and more toward active Xovers with multi amped active speakers (wireless transmissions and cheap amplifiers getting very common).
But now there is one thing I do not understand: if digital recordings are able to move lower frequencies in a whole channel to be sent to the subwoofer, why can't a chip split each channel into low/mid/high frequencies and send those separately so that each signal can be sent to the appropriate driver?
I.e. my question is: can we do without hardware Xovers (whether active or passive) and use software to do the job and avoid the problems created by the hardware?
 

Tim Link

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If you bake the crossover settings into the recording then all speakers have to be set up to handle that. Most speakers will not be able to play the content correctly unless the bass channel is summed back in. 5.1 surround recordings can have a baked in low frequency effects channel that is sent to the subwoofer only.

edit - My answer was based on the idea that you don't want to have active crossovers of any kind actually in the playback system, including ones that use DSP. I'm intrigued with the idea of simplifying the equipment required on the playback side by baking in the DSP crossover filters into the recording, which would now have discrete channels for highs, mids, and lows. It would work I think but would require standardization of speakers to sound right with the pre-determined crossover frequencies and slopes. These files could be re-summed for playback on older systems. I read about tests using headphones where they digitally separated high frequencies from lows and then re-summed them and tested to find out if people could hear the difference between the original file and the split and re-summed file. People could not reliably identify the re-summed files from the originals, which is a testament to how pure and accurate the digital filters can be. When they tried to do the same thing using high quality analog filters people could readily tell the analog filtered and re-summed sound from the original.
 
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Katji

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if digital recordings are able to move lower frequencies in a whole channel to be sent to the subwoofer, why can't a chip split each channel into low/mid/high frequencies and send those separately so that each signal can be sent to the appropriate driver?
I.e. my question is: can we do without hardware Xovers (whether active or passive) and use software to do the job

They do, in the DSP chip. Called frequency division instead of crossover. Plus software control.

So you can have adjustable crossovers, alternative speaker "voicing." Adjustable by controls on the speaker or on the remote control. Instead of the designer deciding which version sounds better overall...instead of committing to that, he can make them both available.
 
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tomtoo

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Hi all,
I am reading a bit about sound basics for personal interest, so have lots of questions.
Reading about the crossovers (passive mainly, but some about active as well) there seems to be a great complexity and the designs seem really difficult by the Experts own admission.
My forecast (worthless of course)is that we'll be moving more and more toward active Xovers with multi amped active speakers (wireless transmissions and cheap amplifiers getting very common).
But now there is one thing I do not understand: if digital recordings are able to move lower frequencies in a whole channel to be sent to the subwoofer, why can't a chip split each channel into low/mid/high frequencies and send those separately so that each signal can be sent to the appropriate driver?
I.e. my question is: can we do without hardware Xovers (whether active or passive) and use software to do the job and avoid the problems created by the hardware?

Thats what a dsp does. Signal comes in, gets split by the gods of math into Frequenzebands. Then send to different ad converters.
 
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A

adLuke

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I have seen the DSP discussions but from what I understand DSP and Xover are very different even if they are conceptually very similar.
But seems like I am wrong given the feedback.
Can any of you give me an indication of a thread to read or a search?
Just looking for DSP seems to bring me far, far away...:rolleyes:
 

somebodyelse

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I have seen the DSP discussions but from what I understand DSP and Xover are very different even if they are conceptually very similar.
But seems like I am wrong given the feedback.
Can any of you give me an indication of a thread to read or a search?
Just looking for DSP seems to bring me far, far away...:rolleyes:
DSP is digital signal processing - whether you use it for speaker/headphone correction, room correction or crossover is up to you. Similarly you can achieve it using dedicated hardware (a DSP chip) or software running on a general purpose CPU - it doesn't really matter, within their respective capabilities. If you look at the crossover software thread and the EQ software thread you'll find a lot of names appearing in both, and the capabilities are broadly similar to hardware options like those from MiniDSP, HifiBerry etc.
 

Katji

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Can any of you give me an indication of a thread to read or a search?
Just looking for DSP seems to bring me far, far away...:rolleyes:
Sometimes you need to add more keywords to focus the search. Google too...I searched for DSP - of 8 results on the first page, 4 are DSP as we know it here (wiki, Yamaha, miniDSP), 3 are Deutsche Schule Pretoria, 1 is Dioxin Sample Preparation. :)
Only this one seems useful:

A Beginner's Guide to Digital Signal Processing (DSP)

https://www.analog.com › beginners-guide-to-dsp
Digital Signal Processors (DSP) take real-world signals like voice, audio, video, temperature, pressure, or position that have been digitized and then ...
 
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adLuke

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Thanks very much for your help @somebodyelse and @Katji
I also found a very interesting thread by @dualazmak about his built:

Multi-Channel, Multi-Amplifier Audio System Using Software Crossover and Multichannel-DAC​



I think I am set for quite a bit of reading.
Thanks all for your contributions
 

dualazmak

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Hello OP @adLuke,

Your visits (and possible participations) to/on my project thread are quite welcome!

I do hope my thread would be worthwhile for your reference, and I will be happy if the thread would provide some suggestions for your progress in system building with XOs and hopefully with multichannel multi-amplifier setup.

As you may already aware of, I have Hyperlink Index posts here and here for my thread for your convenience of jumping to any specific topics there.

dualazmak
 
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