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View Full Version : Worth the extra $ for higher preamp voltage???



rjay
04-21-2011, 11:02 PM
So I am looking at two units; JVC KD-HDR70 or JVC Arsenal KD-AHD79, both are identical except for the preamp voltage. Arsenal has 5volts and other unit has 2.5volts. Only a $10 difference for the Arsenal unit, which I will prob go with. Is there a noticable difference with going with the higher voltage or not really? Only will be running a mono amp (Boston Acoustics 400m).

VWBobby
04-21-2011, 11:59 PM
Higher voltage pre-outs are good for longer RCA runs and lower distortion. Since you don't have to crank your amp gains as high, you have less chance of noise. If the power is higher, it will drive a longer run of RCA's without needing more gain. ;)

Kangaroux
04-22-2011, 12:04 AM
^^^ yea that's pretty much it lol.

go with the 5v.

dragnix
04-22-2011, 12:05 AM
for an extra $10, why the hell not?

RAM_Designs
04-22-2011, 12:06 AM
I like my 8V HU. :D

IMO it makes a difference.

rjay
04-22-2011, 07:33 AM
Thanks for the info. I was going to go with the Arsenal unit anyways, since its only $10 higher, but I was just curious. Thanks again

slim2fattycake
04-22-2011, 09:12 AM
Higher voltage pre-outs are good for longer RCA runs and lower distortion. Since you don't have to crank your amp gains as high, you have less chance of noise. If the power is higher, it will drive a longer run of RCA's without needing more gain. ;)

No, but for 10 dollars why not.

Louisiana_CRX
04-22-2011, 10:04 AM
id save the money and buy a cheap fifth....you can match the amp gains to 2.5 or 5v input....and it will sound the same

jco1385
04-22-2011, 10:10 AM
go for the 2.5v, send me the $10

Buck
04-22-2011, 11:15 AM
Get the 5v. I'm actually considering getting a line driver to bump my pre-amp voltage to 8-9v.

blazeplacid
04-22-2011, 11:22 AM
audibly you wont notice any change

but your mind will constantly think

"what would it sound like if I had paid $10 more for the 5V"

trust me, ive been there. Its all in your head and it will drive you crazy

Buck
04-22-2011, 11:29 AM
audibly you wont notice any change

but your mind will constantly think

"what would it sound like if I had paid $10 more for the 5V"

trust me, ive been there. Its all in your head and it will drive you crazy

Eh, I'd disagree.

Kangaroux
04-22-2011, 11:55 AM
Eh, I'd disagree.

on high enough quality speakers you may notice more noise on a 2v than a 5v. and also, its nice to have 5v in the case that you need to use an RCA splitter because the voltage still stays reasonably high (>2v)

slim2fattycake
04-22-2011, 01:22 PM
on high enough quality speakers you may notice more noise on a 2v than a 5v. and also, its nice to have 5v in the case that you need to use an RCA splitter because the voltage still stays reasonably high (>2v)

How are you going to hear noise from low preout voltage if you set your gain right?

VWBobby
04-23-2011, 11:17 PM
Obviously a lot of people in this thread haven't played around with pre-amps and power amp gain settings....
Anytime you bump up your gain, you are amplifying more noise. Garbage in, garbage out.
Lets say you have a 15 foot run of RCA's from the front to the back and need to crank up your amp 3/4 of the way to match your front speakers. Usually you will hear a slight hiss. The noise floor is higher and sometimes the sound is compressed or squashed sounding.
Anyone who's played electric guitar or bass knows all about the noise associated with high gains, cheap cables (microphonics) and change in tone. Same subtle hints happen in car audio if you listen for it.

In short, there's a reason high quality HU's have 4-8V pre-outs verses the mainstream 1.5-2.5V outputs.

chevy_man
04-24-2011, 01:28 AM
Since you match your gains on your amp to your HU output, going with the 5v pre-outs is going to let you turn the gain up more. This will give you more power output without giving you crazy distortion which happens when you crank the gains with a low pre-out signal. This is the reason every signal processor has an adjustable output, usually to 8-9v since most amps only have a gain setting high enough for 8v.

Phoenix Risen
04-24-2011, 01:34 AM
Since you match your gains on your amp to your HU output, going with the 5v pre-outs is going to let you turn the gain up more.

couldnt be more wrong.

a higher preout voltage will actually let you keep your gain lower and still get the same power out of your amp.

that said. anyone who is saying preout voltage matters. answer me one question.

why is it that a lot of the old school amazing sounding decks have 2mv pre-outs?

billabongcr
04-24-2011, 01:39 AM
couldnt be more wrong.

a higher preout voltage will actually let you keep your gain lower and still get the same power out of your amp.

that said. anyone who is saying preout voltage matters. answer me one question.

why is it that a lot of the old school amazing sounding decks have 2mv pre-outs?

:popcorn:

Phoenix Risen
04-24-2011, 01:41 AM
:popcorn:

ive got my flame suit on. im good to go.

billabongcr
04-24-2011, 01:43 AM
ive got my flame suit on. im good to go.

made a solid statement. cant wait to see whos guna step up

Suicide Bobb
04-24-2011, 01:55 AM
When you turn up the gain on the amp, you do so to match the pre-out voltage on your deck. The input voltage of the amp goes downward as you turn it clockwise (turn it up). Thus, when matching the input voltage of the amp with the pre-out voltage of the deck, you don't need to turn the gain up as high for a higher voltage pre-out. The further you "turn up" the gain on the amp, the higher the distortion levels are. All of these things that I said are FACTS.

Now, whether or not your ears will be able to discern the difference in distortion between, say, 1/4 gain and 3/4 gain is subject to the individual. I myself can EASILY notice the difference. Here's a really easy way to tell: Bring your amp in the house, and hook it up to a car battery (or a battery charger). Connect it to a pair of speakers. Connect a source to it, but don't play any music. Start with the gain down, then turn it up. Notice the increased distortion? That static-y noise? There's proof for you. The distortion is most certainly less noticeable when music is playing, but it is still noticeable to a good ear.


that said. anyone who is saying preout voltage matters. answer me one question.

why is it that a lot of the old school amazing sounding decks have 2mv pre-outs?

That would be because they used line-drivers frequently back then, instead of high pre-out voltage decks.

Wonder why we rarely see line-drivers in SQ installs and more often see high pre-out voltage decks in our current time? One thing they failed to notice when they started toying around with line-drivers was that by adding another electronic do-hicky in the system; which required separate ground, power, remote, and rca inputs; they were introducing further noise. Sure, it's possible to eliminate that noise, but that requires a lot of time, dedication, experience, etc.

Not to mention that it's more convenient to have a deck with high pre-out voltage than having to wire up a separate line driver. It became the obvious choice.

I'm sure I'm going to get a lot of "tl;dr", but for those who read all this, I'm sure it will clear things up.

CLIFS:
These are facts - More gain means more distortion. Higher pre-out voltage means the gain is lower when the voltage matches. Thus, higher pre-out voltage means lower distortion, ceteris paribus.

Suicide Bobb
04-24-2011, 01:57 AM
made a solid statement. cant wait to see whos guna step up

How was that?

---------- Post added at 10:57 PM ---------- Previous post was at 10:56 PM ----------


ive got my flame suit on. im good to go.

Flame-on! lol

Phoenix Risen
04-24-2011, 02:10 AM
good to know.

that actually makes sense instead of people just saying because it is.


thanks bobb

Suicide Bobb
04-24-2011, 02:37 AM
good to know.

that actually makes sense instead of people just saying because it is.


thanks bobb

Glad to hear it makes sense!

VWBobby
04-24-2011, 09:43 PM
Good explanation Bobb... What's funny is that's the same thing I was saying in my post but not in as much detail.

DBfan187
04-24-2011, 10:04 PM
low impedance > high voltage preouts :fyi:

Suicide Bobb
04-24-2011, 10:08 PM
Good explanation Bobb... What's funny is that's the same thing I was saying in my post but not in as much detail.

I did notice that. What they needed was detail. It's like when people hop in a "This vs. That" thread and say that "This" is better without backing it up. It does nobody any good unless you 100% trust that persons opinion, regardless of what it is.

Suicide Bobb
04-24-2011, 10:09 PM
low impedance > high voltage preouts :fyi:

I would like some detail here :)

Buck
04-24-2011, 10:12 PM
I would like some detail here :)

I think he means get RCA's with low resistance, either that or put your line drivers really close to your amps (that would create lower resistance, less length).

Suicide Bobb
04-24-2011, 10:13 PM
I think he means get RCA's with low resistance, either that or put your line drivers really close to your amps (that would create lower resistance, less length).

Oh ok

Buck
04-24-2011, 10:15 PM
Oh ok

I'm just guessing though.

DBfan187
04-24-2011, 10:17 PM
helps reducing noise better than high voltage

DBfan187
04-24-2011, 10:19 PM
I think he means get RCA's with low resistance, either that or put your line drivers really close to your amps (that would create lower resistance, less length).
No, just no. Look for preouts with low impedance than high voltage. I used to do the same by looking for high volt preouts, until I got an Eclipse. I loved that thing!!!

Buck
04-24-2011, 10:20 PM
No, just no. Look for preouts with low impedance than high voltage. I used to do the same, until I got an Eclipse. I loved that thing!!!

Lol I was just guessing.

RAM_Designs
04-24-2011, 10:21 PM
I love the higher RCA voltage because it keeps things sounding clean and quiet when the music requires it to.

Suicide Bobb
04-24-2011, 10:22 PM
No, just no. Look for preouts with low impedance than high voltage. I used to do the same by looking for high volt preouts, until I got an Eclipse. I loved that thing!!!

How do you look for low impedence in preouts?

On a separate note, doesn't your Eclipse have at least 5v preouts?

DBfan187
04-24-2011, 10:27 PM
no it had 2.7v 330ohm I believe, Eclipse CD3434

good thread on it http://www.caraudio.com/forums/head-units/345890-preout-impedance.html

Suicide Bobb
04-24-2011, 10:35 PM
no it had 2.7v 330ohm I believe, Eclipse CD3434

good thread on it http://www.caraudio.com/forums/head-units/345890-preout-impedance.html

OH

ok

thanks :)