[linux-audio-user] open & free soundcard

On Thu, 18 Aug 2005 15:10:50 +0200, joke
<joke@email-addr-hidden> wrote:

> Hi friends,
>
> for some days I was looking for some open & free hardware and specially
> soundcards.
> I find some informations about openhardware... but not really on the
> question of soundcard
> (some dac to build yourself). I would like to know if some of you guys
> using open & free
> soundcard and if not at least a way to do it yourself... or even if you
> know people who had
> a project to release some prototypes or have similar projects.
> I could be really great to use a gnu/linux plateform with so much & good
> free audio software
> and to use an open & free soundcard to record & play this sounds!!

Hi,

AFAIK there are no "open hardware" solutions out there that you could
use to build your own soundcard. It's just that the economy of hardware
manufacturing and writing (free) software is totally different.

It would not be impossible to roll your own, depending on what you mean
by "soundcard" and your level of engineering skills.

Let's assume you want a 8in/8out device with 24/96 capability. It would
be easiest to make an external interface that you could connect to the
PC via (say) firewire. I imagine the board would have some audio codecs,
a firewire (or other) controller, and (say) an ARM to control the
operation of the unit as a whole.

At this point, you would have to

1) design, test and prototype the board. This assumes a fair knowledge
of electrical engineering and system design. As of prototyping, think
of a 2-(or 4-)layer PCB with a good couple of quad-flat-pack SMDs on it,
you're not gonna do it in your backyard.

2) write a (Linux) driver for your device, or provide specs and get
someone else to write a driver. This is admittedly the easier part.

As you can see, 1) poses a certain financial and technological barrier
to entering the "soundcard makers" camp. With the simplest possible
specification, I still estimate the costs of prototyping it to
multi-thousands (in Euro or US$). It's just not economically viable
when the stores are full of dirt cheap hardware.

As to the "dac to build yourself", I would also say nope. Not counting
educational, demo or other such purposes, you cannot build a usable
AD/DA converter. (From discretes, that is. If you are an ASIC supplier,
things look different ;). Common bit-resolutions need such an accuracy
of components (not primarily with regard to absolute ratings, but to
parameter scatter among "identical" components) irrespectively of the
AD/DA conversion method used that the components need to be integrated
on the same silicon. (Think of thermal issues.)

My 2 eurocents. Sorry if this was all trivial.

Tom
Received on Thu Aug 18 16:15:06 2005