[linux-audio-user] A machine for live gigging?

[Clemens Ladisch]

Julien Pierre wrote:
> However, besides the obvious portability advantage of USB devices, there
> is one other interesting feature of USB audio, which is to isolate the
> A/D and D/A converters outside the generally noisy computer case, and
> this can provide higher audio quality than an internal PCI device. But
> only the higher-end USB devices would really have that advantage. I have
> used some low-end ones that were just as noisy as the first ISA
> Soundblaster 1.0 (Edirol UA-1A if you must know).

The UA-1A is bus-powered, and so picks up any noise on the +5V line.

The noisiness of that depends partly on the mainboard, but mostly on
the power supply unit.  On my system with an Asus P4P800 MB and an
Enermax PSU, I don't hear any noise, while on another system with an
Intel TE430VX OEM board and a noname PSU, there is noise.

In the latter case, the CPU is powered by the +5V line, too, and the
noise can be reduced greatly by running distributed.net/SETI at Home/
whatever in the background to prevent the CPU from switching to idle
mode.


Regards,
Clemens