Line level specification?

[David Nebenzahl]

Several recent threads here about connecting audio equipment make me
wonder about "line level" connections. I know what they are and where
they're used, but I'm wondering: is there an industry standard for them?

I know that standard line-level impedance is 47K ohms, but what I don't
know is the voltage level specification, if any. I suspect that there's
no one set voltage level, but isn't there a more-or-less standard
*range* of voltages for line level? (My guess, if I had to take one,
would be somewhere around 100 millivolts.)

Googling doesn't produce any definitive results here.


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[Dave Platt]

In article >,

David Nebenzahl > wrote:
>Several recent threads here about connecting audio equipment make me
>wonder about "line level" connections. I know what they are and where
>they're used, but I'm wondering: is there an industry standard for them?
>
>I know that standard line-level impedance is 47K ohms, but what I don't
>know is the voltage level specification, if any. I suspect that there's
>no one set voltage level, but isn't there a more-or-less standard
>*range* of voltages for line level? (My guess, if I had to take one,
>would be somewhere around 100 millivolts.)

Prior to the development of CDs, the usual standard for line-level
signals was 1 volt peak-to-peak for full-power output.

CD players, when released, tended to use a 2 volt peak-to-peak
full-scale signal. I believe that this was done in order to help
improve the dynamic range of line-level inputs (keeping full-scale
signals further away from the input's noise level).

This 2:1 increase in voltage led to occasional problems. There were
some audio components (preamps, tape decks, etc.) which would distort
(or even clip!) at the higher voltage level. This may have
contributed to some extent to the reputation for "harsh sound" that CD
players developed in the early days.

I'm not sure whether either the 1- or 2-volt-peak-to-peak level was
ever formally standardized by any of the major industry groups.

--
Dave Platt > AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
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[Arny Krueger]

"David Nebenzahl" > wrote in message
.com
> Several recent threads here about connecting audio
> equipment make me wonder about "line level" connections.
> I know what they are and where they're used, but I'm
> wondering: is there an industry standard for them?
> I know that standard line-level impedance is 47K ohms,
> but what I don't know is the voltage level specification,
> if any. I suspect that there's no one set voltage level,
> but isn't there a more-or-less standard *range* of
> voltages for line level? (My guess, if I had to take one,
> would be somewhere around 100 millivolts.)
> Googling doesn't produce any definitive results here.

That's probably because there are no definitive results to find. :-(

Consumer line levels I've encountered vary from maybe 35 millivolts (DIN
jacks) to 100 mv (a typical sensitivity for an RCA jack input on an
integrated amplifier or preamp tape recorder or tuner input) to 1.5 volts (a
typical consumer power amp) to 2.5 volts (a fairly gutsy consumer CD player)

Most consumer gear seems to position the input level control ahead of any
active stage, which helps with the dynamic range situation.

[Richard Crowley]

"David Nebenzahl" wrote ...
> Several recent threads here about connecting audio equipment make me
> wonder about "line level" connections. I know what they are and where
> they're used, but I'm wondering: is there an industry standard for them?
>
> I know that standard line-level impedance is 47K ohms, but what I don't
> know is the voltage level specification, if any. I suspect that there's
> no one set voltage level, but isn't there a more-or-less standard
> *range* of voltages for line level? (My guess, if I had to take one,
> would be somewhere around 100 millivolts.)

Not only is there no "line-level standard voltage", but there isn't even
a standard *impedance.* Perhaps the best you can do is to follow the
history of "line level" from telephony 100 years ago and trace the
evolution (or perhaps more properly "devolution").

Now "professional line level" is much closer to having standard
impedances and levels than consumer "line level" which is all over
the map.

When I am building equipment with "consumer line-level" I design
to: 2V p-p nominal, 100-1K ohm output impedance, and 10K
input impedance.

> Googling doesn't produce any definitive results here.

Sometimes when Google reports that there isn't anything,
it is telling the truth.

[David Nebenzahl]

On 2/15/2010 9:35 AM Richard Crowley spake thus:

> "David Nebenzahl" wrote ...
>
>> Googling doesn't produce any definitive results here.
>
> Sometimes when Google reports that there isn't anything,
> it is telling the truth.

Well, just to be clear, what I meant is that while Google produced lots
of results from my searches, those results weren't at all definitive.
(Not Google's fault, of course.)


--
You were wrong, and I'm man enough to admit it.

- a Usenet "apology"