[linux-audio-user] [OT] recording levels (mismatch)

[Mark Knecht]

On Tue, 12 Oct 2004 19:16:37 -0700, Erik Steffl <steffl at bigfoot.com> wrote:
> Mark Knecht wrote:
> ...
> >>>>  I am trying to record from a receiver (not sure if that's the right
> >>>>name, it's the amp/tuner, the thingy that all other components like CD
> >>>>player, tape deck, video etc. connect to) and it seems like the levels
> >>>>are too low (the soundcard is soundblaster live platinum, using alsa
> >>>>drivers that come with kernel 2.6.5).
> ...
> > 1V amp PP output  -> 1000 Ohm output <---cable----> 1000 Ohm input
> >
> > In the above pirture to voltage the input receiver sees is 50% of the
> > voltage actually driven.
> ...
> > This stuff comes up a lot when interfacing studio equipment. This, and
> > the levels provided as per the post from Andreas, are generall the
> > root cause of this sort of problem.
> 
>    that might be the case, I see the signal being at about 20-40%,
> compared to about 50-70% 'normal' signal (in vu-meter).
> 
>    the big Q remains - what do I do? (I didn't try the headphones output
> yet, but everybody says that headphones output on the consumer receivers
> is of poor quality (then again, I listened to it via headphones and it
> was good enough for me...)).
> 
>         erik
> 
> 

Well, I'd guess the best answer, if this is what's really going on, is
to use an impedance matching transformer of some type. Get a high
input impedance, lower output impedance model. Don't know what this
would cost. Probably not cheap, but not really expensive either. This
is very typical for stage work. they get used to turn single ended
into balanced/differential signals, etc., so that you can run long
distances.

Another possibility would be to find a secondary amp to put in the
middle. A good quality headphone amp or something like that *might*
work.

These are all guesses. Take it with a grain of salt.

- MArk