Let's create an 'open source' hardware project.

[gmarsh]

Just like the Jehovah's haven't converted me by knocking on my door hundreds of times, I fear that hundreds of posts in ZMB's thread isn't going to make many people actually want to pursue open source. Perhaps something more tangible can get people excited.

We've got plenty of experience on this forum in analog/digital audio design, clock design, DSP, and who knows what else. Who says we can't pool a few of our talents together, use a few heads, bang a few heads and create some sort of open, collaborative, "big" yet fun hardware project with a DIY audio theme?

My idea of an "open source" hardware project is something like what the ADI Blackfin DSP geeks are up to. They've taken a cheap DSP chip, created a "BF533 STAMP" board with lots of ram/flash/peripherals and a range of add-on boards, and ported ucLinux and the GCC compiler toolchain to the DSP. http://blackfin.uclinux.org/ has all the details on that.

Drawing inspiration from that but thinking "audio! audio!", what's a project we could undertake? Here's a couple of ideas:

- a DSP board, a Behringer DEQ type of thing, which could be used for active speaker crossovers, room equalization, and who knows what else.

- A digitally controlled preamp, receiver, or something in between.

Thoughts? ideas? comments?

[BrianDonegan]

Aren't all the project (or most of them) posted here open source? I think we may be confusing "open source" with "do-it-all"?

[gmarsh]

Originally posted by BrianDonegan
Aren't all the project (or most of them) posted here open source? I think we may be confusing "open source" with "do-it-all"?

If you publish your hardware and software designs - PCB's, HDL, uC/uP source code, etc... and do so under a public domain or perhaps GNU/BSD license, it's "open source" IMO. And that counts as lots of things.

I guess what I'm suggesting is a "perhaps too complicated for 1 guy in his spare time" type of collaborative project - with all the aspects of the design made public.

[chris719]

Maybe some kind of digital filter where one could choose from many filter profiles and just upload the code to the DSP? Although digital filtering might be better suited to FPGAs.

[rfbrw]

How about a minimal disk based record/playback system. If more is needed it can be added.

[chris719]

Sounds good, PATA would interesting to implement as you could then use formatted compact flash cards instead of hard disks if you wanted for noise reasons, and still maintain compatibility with HDD. Although, today's fluid bearing 7200 RPM drives are pretty much inaudible from a few feet away depending on the model.

[hifimaker]

Interms of a DAC, it would be great to incorporate balanced analog outputs and a modern DAC chip like the the TI/BB 1792/4 or the Wolfson 8740. The Chinese Zhalou 2.5 had interesting feature of placing the core DAC chip on a daughter card that allowed interchangeble DAC modules. Designing a base set of capabilities that are augmentable with a daughter card for the DAC chip and I/V stage would be an interesting concept. A design platform approach might have a broader acceptance in our community. There is also a lot of knowledge over at www.head-fi.org, and the Pitcan Island guys (former www.diyaudio.com folks)over at www.diyhifi.org.

Designing DAC's seems to be a specialized art. It is surprising how few DIY DAC designs are not built around more modern DAC chips. Especially given how long 1792/4 and 8740's have been in production and well reviewed commercial implementations around these chips have been.

Something to consider.

-David

[chris719]

Since I doubt people will agree on a DAC like you said, maybe the player or DSP only has to output SPDIF or I2S.

[BrianDonegan]

it would be great to incorporate balanced analog outputs and a modern DAC chip like the the TI/BB 1792/4 or the Wolfson 8740

http://www.diyaudio.com/forums/showt...47#post1004747

[gmarsh]

Originally posted by chris719
Maybe some kind of digital filter where one could choose from many filter profiles and just upload the code to the DSP? Although digital filtering might be better suited to FPGAs.

DSP's are specifically designed for digital filtering - a MAC instruction is 99% of the time used to process an IIR or FIR filter tap.

And DSPs tend to be muchmuchmuch cheaper than FPGAs - you'll find FPGAs doing filtering at very high sample rates (>10MHz) while DSPs are used almost universally at audio rates.