[falz]

What exactly is the benefit of having a lower numbered impedance from
RCA pre-amp outputs of a head unit? It certainly seems that higher
voltage outputs is generally better, but how do lower Ohms fit this
equation?

For example, the 2007 Pioneer decks have 4v output, but the lower end
models are 1k ohm (DEH-P390MP) , while as the products get more
expensive (DEH-P490MP), they are 100 ohm. Can someone spell this out
for me? Is less noise introduced into the signal at lower impedance,
or is that only related to higher voltage? Are all higher voltage (4v
+) units 1k ohm?

--falz

[GregS]

In article .com, "falz" wrote:
What exactly is the benefit of having a lower numbered impedance from
RCA pre-amp outputs of a head unit? It certainly seems that higher
voltage outputs is generally better, but how do lower Ohms fit this
equation?

For example, the 2007 Pioneer decks have 4v output, but the lower end
models are 1k ohm (DEH-P390MP) , while as the products get more
expensive (DEH-P490MP), they are 100 ohm. Can someone spell this out
for me? Is less noise introduced into the signal at lower impedance,
or is that only related to higher voltage? Are all higher voltage (4v
+) units 1k ohm?

For one thing, you can more easily split up the output, and it will just
have less load effects. Thats about it. Most equipment uses op-amp
for the output, and most can't deliver much power, so high resistors
are used to stabilize and protect them. To have a 100 ohm drive means having
a beefy stage, probably just a headphone driver. Since it can't stabilize
ground noise, it does nothing else.

greg

[falz]

On Feb 5, 7:46 am, (GregS) wrote:
For one thing, you can more easily split up the output, and it will just
have less load effects. Thats about it. Most equipment uses op-amp
for the output, and most can't deliver much power, so high resistors
are used to stabilize and protect them. To have a 100 ohm drive means having
a beefy stage, probably just a headphone driver. Since it can't stabilize
ground noise, it does nothing else.

Looks like it doesn't do a whole heck of a lot in my scenario then,
I'm not sure who would be splitting RCA output when even relatively
inexpensive decks have front/rear/sub pre-outs! Thanks for the answer.

--falz

[Chad Wahls]

"falz" wrote in message
oups.com...
What exactly is the benefit of having a lower numbered impedance from
RCA pre-amp outputs of a head unit? It certainly seems that higher
voltage outputs is generally better, but how do lower Ohms fit this
equation?

For example, the 2007 Pioneer decks have 4v output, but the lower end
models are 1k ohm (DEH-P390MP) , while as the products get more
expensive (DEH-P490MP), they are 100 ohm. Can someone spell this out
for me? Is less noise introduced into the signal at lower impedance,
or is that only related to higher voltage? Are all higher voltage (4v
+) units 1k ohm?

--falz


More drive current available. It helps in reducing noise somewhat as the
signal is not as easily "pushed around" My RFI and EMI. The lower the
output impedance the better regardless of how many times it will be split,
etc.

Chad