Re: RCA Output voltage

High-voltage outputs theoretically *allow for* greater dynamic range, better noise *immunity* (not just covering it up), and overall better S/N. To see any REAL benefit from it, however, your next downstream component (amp, crossover, whatever) needs to be able to accept the greater input. If your amp's input clips any anything over, say, 2V, you won't be able to crank the deck's output any more than you would a standard deck, and you won't see any significant difference.

As an example, if your system has a noise floor of 0.05V (I'm just pulling numbers out of my ass here for the sake of illustration, BTW - these things are normally measured in dBu, dBV, or other similar scales, rather than in absolute voltages), and your deck has a max output of 1V (actually, I think 1.8V is most common, but I'll use 1V for easier reference), the noise will be a lot more noticeable than if your deck can push signal at 5V, and thus much higher above the noise floor. (Just a quick calculation in my head, I believe the 1V example would be only a 13dB S/N ratio; the 5V example would allow up to 20dB... assuming, again, that the amp or crossover's input can accept that level).

This actually is not a new concept... pro audio gear has for decades traditionally used +4dBm as a "standard" signal level, while consumer (home) audio equipment uses -10dBm. Connecting, say, a home tape deck's output to a pro mixer's input requires a lot of input gain, and with it increased chance of noise, while feeding a pro mixer's output to a home tape deck requires careful control of the output gains to avoid clipping the deck's inputs. Pro gear, of course, uses the "hotter" signal for exactly the same reason: better dynamic range, better noise rejection, better S/N ratio.


MOSFET wrote:
A couple of things. First, when a HU says 4 or 5 volt pre-amp (RCA) output,
that is a maximum number. Nominally, your HU typically puts out a much
lower voltage. Also, pretty much EVERY HU made today puts out AT LEAST 2 or
more volts which, 15 years ago, was considered high voltage. So there
really isn't much difference between the high voltage and low-voltage
outputs.

Second, I have owned a high voltage (4 volts) HU (an Alpine 7939) and
several non high voltage HU's (2-3 volts) including my current HU, an Alpine
9853, and I don't notice any difference in sound quality. I think this
whole voltage thing has more to do with marketing than any meaningful sound
quality improvement. As I frequently point out, if 4-5 voltage pre-amp
outputs were the end-all-be-all, why don't multi-kilobuck high-end home
equipment (Mark Levinson, Krell, Conrad Johnson, etc.) use them? The
answer is that THEY DON'T help sound quality wise.

What they CAN do, however, is sometimes cover up induced noise problems
(like alternator whine caused by ground loops) by allowing you to turn the
gains on your amp lower. However, I see this as a band-aid. A 5 volt
pre-amp output may allow you to REDUCE noise problems, but it can never
ELIMINATE them. A good installation with proper grounding on all components
CAN ALWAYS (at least in my experience) eliminate ground-loops. And other
types of induced noise can be dealt with as well. To me, it makes more
sense to deal with the problem, rather than trying to cover it up.

So for that and other reasons, I don't see much benefit in high voltage
outputs (of course, I don't think a high voltage output HURTS anything). I
just wouldn't make that a very high priority in selecting a HU.

My $.02,

MOSFET

"Deez Nutz" <aaron_inscho@xxxxxxxxxxxxxxx> wrote in message
news:1156913819.133798.235180@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

I was curious to know does it matter the amount of voltage a hu put out
to the rca jacks? I have a Boss hu and it says it has 5 volt pre amp
outs. I am fixing to get a new car in which I will be purchasing a new
hu, and I wanted to find out if the voltage output was something to
weigh into the decision. Thanks in advance for any and all suggestions.




.

Relevant Pages

  • Re: Megapixels and noise
    ... ISO Camera ADC DN Gain Read S/N on ... Max photons (volts) electrons noise 18% gray card ... You are saying column 3 is correct and ADC quantization ...
    (rec.photo.digital.slr-systems)
  • Re: Megapixels and noise
    ... ISO Camera ADC DN Gain Read S/N on ... Max photons (volts) electrons noise 18% gray card ...
    (rec.photo.digital.slr-systems)
  • Re: Megapixels and noise
    ... ISO Camera ADC DN Gain Read S/N on ... Max photons (volts) electrons noise 18% gray card ... You are saying column 3 is correct and ADC quantization ...
    (rec.photo.digital.slr-systems)
  • Re: Why Is High Feedback Considered Bad In Audio? In Simple Terms
    ... adrian@xxxxxxxxxxxxxxxxxxxxxxxxxxxx (Adrian Tuddenham) wrote: ... What sort of noise levels do you need? ... AFAIK they're still unbeatable for high voltage low current switching ... rheostat allowing manual charge rate adjustment. ...
    (sci.electronics.design)
  • Re: Why Is High Feedback Considered Bad In Audio? In Simple Terms
    ... adrian@xxxxxxxxxxxxxxxxxxxxxxxxxxxx (Adrian Tuddenham) wrote: ... What sort of noise levels do you need? ... AFAIK they're still unbeatable for high voltage low current switching ... rheostat allowing manual charge rate adjustment. ...
    (sci.electronics.design)