[LAU] sortof OT -- ART tube pac preamp and compressor noisy?

Fons Adriaensen fons at linuxaudio.org
Tue Aug 13 15:53:38 UTC 2013

On Tue, Aug 13, 2013 at 08:08:38AM -0700, Rusty Perez wrote:

> Fons, you're right. I'm going from the xlr out on the tube pack to one
> of the xlr ins on the delta 1010lt. I kindof figured that was
> understood since I mentioned the xlr connections, but one cannot
> assume. Anyway, I'll look at the jumper situation. I really don't want
> to take my machine apart though. :-)
> Do I understand correctly that set on the mic setting, the card gives
> the xlr ins a 60 db boost?

According to the manual, +30 dB. Which is really too much if the
signal is coming from a preamp which can itself provide +60 dB. 
What happens is that the preamp produces a very low level hum,
and you boost that +30 dB. If you set the 1010lt to lower gain
you can send a stronger signal from the preamp, and the relative
level of the hum will be lower.

Unless the hum is generated at the input of the preamp. You can
easily check this (see if the hum depends on the gain setting).

> Also, when I get really close to my ART tube pac unit, I hear a quiet
> humming from the box itself. Is this normal for a piece of equipment
> with tubes in it? :-) Could this suggest a problem, and is this hum
> introducing itself in to my signal at low levels.

That is normal, what you hear is probably the transformer
of the power supply.



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