[sdiy] Request brain dump on balanced lines

[metasonix]

> Impedance=600 ohms
> Levels? I think they run +4dB which would be 1.225Vrms
> or 3.5Vp-p. As far as I/F circuits go, transformers
> sound better, but active is cheaper. 

The old broadcast standard was 0 VU defined as 
0 dBm = 1 milliwatt into 600 ohms
which is 0.7746 volts rms.
Most professional balanced gear produces / accepts +4 dBm. 
Semi-pro devices often can't put out that much. 
-10 dBm is more commonplace, especially with unbalanced
line level connections.

Decent professional balanced gear should be able to put
out +20 dBm or more into a 600 ohm load.

In a lot of vintage transformer-coupled gear, 
one sees inputs and outputs with impedances from
50 ohms to 1000 ohms. 
150 or 250 ohms was often used with microphones.


> For the ultimate in transformers, check out:
> http://www.jensen-transformers.com/

Jensens are excellent, but I know companies that make
even better ones....


-- 

Eric Barbour
Owner, METASONIX (www.metasonix.com)
Senior Editor, Vacuum Tube Valley magazine