Direct recording of digital audio signals in Ardour?

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audiodef
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I was just reading "Principles of Digital Audio" (I've read the third edition and was reading the sixth edition for the first time) when I was struck by a thought.

After I picked myself up and reported the thought to the police for assault and battery...

Most of my synths are digital. Be they analog modeling or otherwise, just before the audio outs, the signal is already digital. The signal goes through a D/A converter, travels to my mixer, where it is then re-sampled by Ardour when I record.

Is it just me, or is there a completely unnecessary step in here? Is there any way to simply send the already digitized audio signal to Ardour and bypass the need to re-sample a signal that was already a sampled signal to begin with? Or is my understanding of digital synth technology completely off (if it is, please be gentle!).

seablade
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It depends on your synth. If it is truly generating a digital signal and converting that to analog, then in theory it is possible, but whether the synth has a digital output is a different matter all together, and needs to be answered first.

Seablade

audiodef
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Most of them do not have digital outputs. I think two of them have SPDF outs. I guess it was worth thinking about. Maybe someday digital outs will be standard on synths. Come to think of it, I'm surprised that's not standard already.

seablade
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@audiodef

Just to be clear, you are aware S/PDIF is a digital out right?

Seablade

audiodef
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Yep.

I checked, and my V-Synth and Triton Extreme have S/P DIF outs. I'm still limited by not having the corresponding digital input on my sound cards, which are actually just two Firewire mixers.

The more I think about it, the more I'm wondering why this isn't a standard out for synths.

seablade
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Because in many cases anything short of AES output isn't used on a stage for various reasons (Length and non-locking connectors being the typical) and the outputs of synths like that tend to be designed with the stage in mind as much as the studio, if not more.

By the way, I thought the Triton had ADAT as well, but that might just be an option of the guy I knew who had one.

Seablade

ccaudle
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@audiodef:
> The more I think about it, the more I'm wondering why
> this isn't a standard out for synths.

Digital audio requires that different streams all be synchronized to the same clock in order to inter-operate (e.g. be mixed together).

So either you would be limited to using one synth at a time connected to your sound card digital input, or you would have to use a studio master clock, and each synth would require a clock synchronization input to force the local clock to slave to the studio master clock, along with the digital mixer which would be required, or the digital mixer would need asynchronous sample rate converters on each digital input so that all the incoming non-synchronized digital streams could be resampled to the local mixer clock before being mixed together or routed to the outputs.

Do you have a studio master clock? Do you really want to wire a clock tree to each device, in addition to the outputs coming from each device? Are you going to replace your mixer with a digital mixer, or with an audio interface that has enough digital inputs that you can do all the mixing in Ardour?

I think the reason it isn't standard on synths is because it is more trouble than it is worth for a synth. As you noted, some of your synths have it, but in a way that is only partially useful in a large studio environment (i.e. they don't have AES format outputs, and they don't have clock sync inputs). Probably decent balanced analog outputs would be more useful than digital outputs.