The design of active crossovers- Douglas Self wants your opinions - Page 11 - diyAudio
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Old 5th January 2011, 10:30 AM   #101
Previously: Kuei Yang Wang
 
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Hi,

Quote:
Originally Posted by MatchASM View Post
As a German native, you may be interested in an article from the January 2011 issue of Stereoplay. It describes how we got to the current state where virtually all large-scale PA XOs are DSP-based, to correctly steer the many driver arrays that are commonly used. It's a nice little summary of history, of which I find especially the beginning very interesting (although developments then were much slower than they are now).
This sounds very interesting.

I still remember the early analogue "processor" PA systems and the beginnings of "steered arrays" before I got out of Pro-Audio. Almost all implementations I see nowadays for larger scale PA's are simply infeasible without DSP.

As usual, the Pro-Audio side is in the Vanguard, HiFi will catch up.

I am already beginning to see "steered directivity" systems for home AV applications.

Ciao T
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Old 5th January 2011, 11:04 AM   #102
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Quote:
I am already beginning to see "steered directivity" systems for home AV applications.
They are in fact available for quite some time now:

Digital Sound Projector - Yamaha - United States

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Charles
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Old 5th January 2011, 11:15 AM   #103
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Hi,

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Originally Posted by phase_accurate View Post
They are in fact available for quite some time now:

Digital Sound Projector - Yamaha - United States
IF (big if) I understood the way these work they are not classic steered arrays... But I may be wrong.

Ciao T
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Old 5th January 2011, 12:49 PM   #104
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They indeed are steered arrays but not classic ones. They are indeed about 4 arrays in one !!!

1. Front center direct radiating
2. Front left and right: for each one a steered beam that is meant to bounce off the sidewalls.
3. Back: steered beam that is meant to bounce of the back wall with an intermediate hop via the ceiling.

It has some dozens of tiny wideband drivers each with its own tiny class-d amp.

Regards

Charles
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Old 5th January 2011, 01:25 PM   #105
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Hi,

Quote:
Originally Posted by phase_accurate View Post
It has some dozens of tiny wideband drivers each with its own tiny class-d amp.
My understanding was that the drivers as such where not actually fed audio as such, but just (digital) impulses.

Maybe this was about a prototype, instead the real ones went back to traditional steered arrays?

Ciao T
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Old 5th January 2011, 01:50 PM   #106
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Originally Posted by janneman View Post
Matt,

You'll find that most DSP vendors like TI and ADI have turn-key software packages that reduce the programming effort to graphically interconnect functional blocks on the screen and downloading to the DSP. Some or free, some aren't, and you still need to know what you're doing, but there's no need to get down into the weeds anymore.

jan didden
This is certainly interesting and requires more investigation I think
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Old 5th January 2011, 02:51 PM   #107
Davey is offline Davey  United States
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Yes, there are a number of DSP solutions. The ADAU devices from Analog are popular and a development kit and SigmaStudio software are available. Some of these setups are the heart of a few commercial solutions (like the miniDSP) as well.

SigmaStudio? Graphical Development Tool | SigmaStudio Overview | ADAU1701 | Audio Signal Processors | Audio/Video Products | Analog Devices

Cheers,

Dave.
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Old 5th January 2011, 03:13 PM   #108
dewardh is offline dewardh  United States
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Originally Posted by ThorstenL View Post
Secondly, you would need to cover the issues of interfacing the digital world with the analogue one, an area where in much of the available gear appalling atrocities are committed. This is probably one area where your unique abilities and skills can add much and when I last looked you had not really done much work there (DAC and ADC interfacing has some unique challenges)...
It was probably a tiny bit of exageration when I wrote that the only (low level) analog circuits of (any remaining) interest were microphone pre-amps . . . you are correct in noting that the interface to the A/D converter and from the D/A remain. But if ever there was a function that suggests a single-chip "solution" that's it, and if the chip designers haven't done it already I'm sure they soon will. Something like the INA134 and DRV135, perhaps, optimized for direct connection to the converters (if those won't work as-is).

A discussion of crossovers, then, would be about . . . crossovers (or more accurately, signal splitters). A discussion of how we implemented them back in the dark ages with analog circuits would make a welcome chapter (that could be skipped by anyone interested merely in modern crossover design and implementation), but all the important aspects of the entire "crossover" discussion could be done without a single reference to physical implementation. The following chapter on how we "make it real" would take only a couple paragraphs to show why it's no longer done "analog" except in the most trivial cases (small two-way active monitors, for example).
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Old 6th January 2011, 03:37 AM   #109
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It seems the thread has drifted to another book about another related subject.

As one who is in the process of of converting a near-field 2-way to active crossover, I'm actually interested in the OP subject. I don't see that DSP makes any economical sense in simple or analog speaker systems unless it is part of a larger digital system such as PC based, Home Theatre or as earlier discussed; commercial installations.

I accept that others, professionals particularly, may now be accustomed to all-digital processing in audio, at least in their workplace or at the computer desk. This does not mean that we all use these systems or have any need for ongoing adjustability or complex functions in crossovers. So how about a little more constructive thinking on the OP subject?
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Old 6th January 2011, 03:53 AM   #110
Pano is offline Pano  United States
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Originally Posted by Ian Finch View Post
So how about a little more constructive thinking on the OP subject?
You mean this?

Quote:
Originally Posted by DouglasSelf View Post
I would be very glad to know about it if anyone thinks that anything is is missing. Even in 480 pages I cannot hope to cover the whole field, but I want to make sure that nothing important is left out.
I thought that was (mostly) what folks were talking about.
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