RCA Output voltage

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.

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" > wrote in message
oups.com...
> 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.
>

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" > wrote in message
> oups.com...
>
>>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.
>>
>
>
>

i havent read all the dribble others have wrote but i know
this........(((5v is very very good))) cause alot of amps wont take
more than that but they could start making amps to take more volts from
outputs.
i have 2 jensen cd players with 5v outs...i love them more than any
other piece of car audio i ever owned..
the sound is increditable.
yes it makes a giant difference...
never go under 5v outs...

also you look at high priced recievers theyll have 5v outs......

heres 1 of my secrets. go look at a $500+ reciever n try to find 1 like
its specs for less.

Pro gear, of
> course, uses the "hotter" signal for exactly the same reason: better
dynamic
> range, better noise rejection, better S/N ratio.
>
Pro gear typically uses balanced signals, unlike home and car pre-amp
outputs, which COMPLETELY irradiates extraneous noise (which is necessary in
a pro environment where you typically have VERY long pre-amp runs AND all
sorts of electromagnetic interference).

MOSFET

better
> noise *immunity* (not just covering it up),

How is better noise immunity NOT covering noise up? THINK about it. It's
the same thing, Matt, just another way of looking at it.

I mean, you either have a noise problem or you don't, right? So IF YOU DO,
and your "noise immunity" (as you call it) comes into play, explain to me
how that is not just another way of saying covering up the noise.

Sometimes I get the feeling your turning into Captain Matt.

MOSFET

And one more thing, while we're on the subject, Matt....

How about answering the OP's question? I mean, your post was VERY
impressive sounding and all (even though it made about as much sense to me
as one of Bob's rants). But I reread it and noticed you didn't answer the
question.

QUESTION:
Deez wants to know will a high voltage HU make an audible difference:

ANSWER:
Brandonb: Nope
Me: Tried both kind, didn't hear a difference.

You: Theoretically blah blah noise floor at -10dBm vs. +4dBm dBu, dBV, DVD,
VCR, ESPN blah blah blah....

Will Deez hear a difference, Matt? Yes or no?

MOSFET

MOSFET wrote:
> Pro gear, of
>
>>course, uses the "hotter" signal for exactly the same reason: better
>
> dynamic
>
>>range, better noise rejection, better S/N ratio.
>>
>
> Pro gear typically uses balanced signals, unlike home and car pre-amp
> outputs, which COMPLETELY irradiates extraneous noise (which is necessary in
> a pro environment where you typically have VERY long pre-amp runs AND all
> sorts of electromagnetic interference).

"Irradiates"? Heheheh... only in a nuclear-powered system

Not all pro components have balanced I/O... most, but not all.

Balanced I/O reduces and ALMOST completely erradicates (I think that's the word
you were after) noise *induced in the wiring* (not completely, and not in all
instances - check out various stories around the 'net of church sound systems
pickup up truckers' CBs!) but have no effect on various noise floors inherent in
all electronic gear.