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#1
Posted to rec.audio.car
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"Low Ohm" RCA preamp outputs (100 ohm vs 1k ohm?)
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 |
#2
Posted to rec.audio.car
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"Low Ohm" RCA preamp outputs (100 ohm vs 1k ohm?)
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 |
#3
Posted to rec.audio.car
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"Low Ohm" RCA preamp outputs (100 ohm vs 1k ohm?)
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 |
#4
Posted to rec.audio.car
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"Low Ohm" RCA preamp outputs (100 ohm vs 1k ohm?)
"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 |
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