Low cost dsp based crossover module - diyAudio
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Old 7th December 2009, 01:18 PM   #1
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Default Low cost dsp based crossover module

Hey guys,

Been following diyaudio threads for a while on how to build crossovers for a custom set of active loudspeakers but not knowing all the parameters of my enclosure/drivers i'll choose, I hardly see how passive crossover would be efficient option...A digital crossover rack mounted unit is also a bit out of my budget...:-(

Doing a google search, I found this neat small DSP module that could be used as a digital crossover. www.minidsp.com
From what i understand, It's a small DSP with a PIC that is configurable via their software. It's a startup from Hong Kong from what i can see, anybody heard of them? At 125USD/module, it sounds like a great fit for my student budget!

I'm planning to get a board this week and will let you know how it goes. Will follow up with some pics and review of how it sounds.

In the mean time if any of you has any other suggestions, let me know!
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Old 7th December 2009, 06:27 PM   #2
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Can't wait to hear about your experience. The website is a little lacking on details. If they could provide a simple IDE for developing DSP algorithms this could be a fantastic user community supported project.
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Old 7th December 2009, 10:19 PM   #3
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Alright, will order the board today and let you all know how it goes! I wanted to make a 3 way box, but for now on, a bi-amped box will be a good start! :-) With one module, I can do my left and right, so i just need a small stereo amp module and i'll be good.

But yeah, I agree with you about the website. Needs a bit more details on how to configure the module... The link I found useful is the manual that I got from here. It seems dead nut simple to load/reload configurations or modify the algorithm settings.

I'll try to send an email to their support to see if the IDE is an option... For now on, I can't see myself writing DSP algorithms though... As long as their plug-in configuration works and they update them with new ones, I'll be happy!
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Old 8th December 2009, 02:09 AM   #4
gooki is offline gooki  New Zealand
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Interesting - keep us up-to-date.
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Old 8th December 2009, 04:29 AM   #5
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Before his sad passing, Bob Stout mentioned he was working with some sort of low cost usb programmable dsp chip.

I think a really interesting area for DIY would be wavefront reconstruction and similar dsp heavy approaches. It's something the home audio industry will take quite some time to adopt, since product lines are format driven (ie 5.1).

I'd love a board that combined:
- reasonable FIR capability
- DAC
- an IC based amp of modest power
- ethernet connectivity with PoE

Combine such a thing with reasonable cost full range drivers and a few woofers, and one play around with all sorts of wavefront forming approaches at fairly reasonable cost.
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Old 8th December 2009, 01:13 PM   #6
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Alright! Ordered the board and got a reply from them that i should receive by mid week. Gotta get my cabinet and speaker ready now! Darn... :-)

Wigginjs, I did ask in a separate email to them if they were planning to issue an IDE for the board, and already got a reply.. (man, they're fast!:-)
From what the dude said in his email, IDE is not going to happen anytime soon. Too much work to support the product and problem with making their tools available to everybody (not open source I guess?). On the other hand, he did say that if I had some specific ideas, they would put them together and add them together for future configurations.. Fire them an email with your comments/ideas, you'll see that they've been really responsive with my questions...

Jason, i like the idea of PoE + DSP, neat idea but isn't PoE is only 15W? Or I guess that you could power it with a PoE injector of whatever you need?
Their website talks of future boards so I did ask them what's the deal with that... Apparently, it'll come out end of December/early next year and is basically Digital In/Out and Digital Amp.... maybe what you're looking for...

Anyway, more to follow when I receive the actual board!
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Old 9th December 2009, 01:58 PM   #7
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These look interesting.

I want to create a three way active crossover but with these it looks a little problematic..

If I could take a mono input to two of the units and output four bands (tre,mid,wof,sub) from each I'd at least have a configurable crossover. Might need a y adaptor across the two input rca's (would that work?)

The problem comes when controlling them. Presumably I'd need to run the software twice, once for each device.

Then comes using them with a digital input. Would it be possible to have a single digital in, controllable with a single potentiometer for analogue output level, again with the same crossover outputs.

My knowledge of electronics is very limited!

Like you I intend on building my own three way speakers and find the idea of building passive crossovers much less appealing than buying some power amps and passive crossovers.

Regards,

Jai
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Old 9th December 2009, 05:16 PM   #8
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very nice, maybe it can be used to biamp an OB as well
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Old 9th December 2009, 05:34 PM   #9
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Quote:
Originally Posted by Crossoverman View Post
Jason, i like the idea of PoE + DSP, neat idea but isn't PoE is only 15W?
Yeah, it's only like 12W usable also. But for wavefront synthesis approaches the whole goal is to have the sources summing coherently, so I don't think per source gain is as important. Though comb filtering will cause a loss at high frequencies depending on the spacing that you may need some power to overcome.
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Old 9th December 2009, 05:41 PM   #10
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Quote:
Originally Posted by jason_watkins View Post
Before his sad passing, Bob Stout mentioned he was working with some sort of low cost usb programmable dsp chip.

I think a really interesting area for DIY would be wavefront reconstruction and similar dsp heavy approaches. It's something the home audio industry will take quite some time to adopt, since product lines are format driven (ie 5.1).

I'd love a board that combined:
- reasonable FIR capability
- DAC
- an IC based amp of modest power
- ethernet connectivity with PoE

Combine such a thing with reasonable cost full range drivers and a few woofers, and one play around with all sorts of wavefront forming approaches at fairly reasonable cost.
Stuff like this makes me wish I hadn't dropped out of uni! That's exactly what I was learning to do at uni, including DSP programming and the maths involved, etc... Oh well.

It would be nice to see affordable commercial DSP crossover units (or do they already exist?) Affordable is quite a variable though, I appreciate.

[Edit] - fellow Arsian? :d
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