# High preamp voltage and low ohm line-out impedance



## dsw1204 (Mar 23, 2015)

Just wanted to get a little more understanding of my old Eclipse 8-volt head units. I understand the 8-volt preamp voltage...the higher the preamp voltage the lower the gain settings on the amplifier, right?

But, I do not quite understand what the "55 ohm line-out impedance" means. Can one of you knowledgeable people tell me what that means and how it makes the sound better? 

I appreciate any info you guys can tell me.


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## dsw1204 (Mar 23, 2015)

I was really hoping someone could enlighten me on this subject. Surely, someone knows. Any of the old-school Eclipse gurus out there?


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## JPOSEY (Nov 9, 2011)

I'm no electrical engineer, but you are right regarding the higher voltage outputs. The gains on the amplifier can be set lower therefore their is lower noise floor. The 55 ohm impedance was important when connecting multiple amplifiers to the same outputs. Back in the 80's we generally only had one or two sets of rca's and if the impedance was worse the signal would not be able to drive multiple amps to their optimum levels. I'm sure someone can explain it better than me.


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## dsw1204 (Mar 23, 2015)

I remember, somewhere on this forum, a discussion where one member was talking about a Pioneer head unit had 4 volts and was comparing it to an Eclipse 8 volt unit. His explanation was, if I recall correctly, was that since the amp being used had an input sensitivity of only up to 4 volts, that the Pioneer would be as quiet as the Eclipse. Another member was arguing with him that since the Pioneer's line-out impedance was 400 ohms and the Eclipse was only 55 ohm, that that made the Eclipse the better unit. But, he did not explain why that made it better.

Thus, the reason for my thread here.


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