[Elecraft] LINE OUT output too low?

[Jim Brown]

On Wed, 17 Dec 2008 07:28:32 -0500, Paul Christensen wrote:

>> "FWIW, standard Line Out is 1Vp-p at 600 ohms line impedance.  matt"

>I think you'll find standard, nominal "Line-In/Out" consumer levels to be 
>referenced to -10 dBV irrespective of Z, where 0dBV = 1 Vrms. 

Yes. 600 ohms has not been part of audio practice, pro or consumer, for at 
least 40 years. ALL line level and mic level audio circuits, pro and 
consumer, are low impedance source, high impedance termination. The signal 
is transferred as a voltage, not as power or current. Typical output 
impedances are on the order of 100 ohms, input impedances are typically 
10K for pro line level, 50K for consumer line level. 100 ohms is chosen 
primarily because it is a good value for isolation of op amps from the 
capacitance of the cable that it drives. This capacitance can be 
significant in pro installations, but rarely in consumer applications. 

>This standard started with the old IHF, merged into EIA, and then 
>somewhere along the way I believe AES became the recognized 
>standard-setting organization in North America.  K9YC would know

I can't speak to the history of these standards, but The AES Standards 
Committee is an international body, of which I am a member. 

>-10 dBV is equivalent to 0.316 Vrms.  If we assume a worst-case 10 dB 
>peak-to-average ratio (and probably a lot less depending on the K3's AGC 
>menu settings), then the maximum distortion-free signal voltage handling 
>required is 0 dBV or 1 Vrms or 2.83 Vp-p.

Yes.

For those who are interested, there's more on this in the tutorials on my 
website. http://audiosystemsgroup.com/publish

73,

Jim Brown K9YC