RCA PREAMP VOLTAGE

[kryptonitewhite 1]

I know it's hard to do apples to apples, different ohm loads "Output Voltage and Impedance 8V/55 " different THD's "Total Harmonic Distortion (THD): 0.008%" yadda yadda...frequency range, voltage.

I have been looking to switch from Alpine to Eclipse on the simple thought that Alpine is usually 4-5V where eclipse can be 8V and upwards.

Help me out here guys!

[JimJ 11]

Do you have an inducted noise problem now?

I wouldn't swap out head units simply because of preout voltage...I'd do it for something worthwhile, like preferring one interface over another, different features, better processing...

[kryptonitewhite 1]

I haven't had my CDA-9855 since last january, my X-girlfriend got it in the break up. . Back before that, we considered selling it to get an Eclipse, I don't remember which one, but the main reason was the 8V...though no, I didn't have a problem at the time, except with the crossovers. I had 2 CDA-9855's and both suffered from a "pop" sound once in a while at certian frequency peaks that corresponded with different crossover points/slopes.

So really, now that i'm starting from scratch as far as the source goes, I'd prefer the highest voltage possible along with everything else into consideration of course...cause at the end of the day, all gains at minimum would just mean minimal amplification of outside noise, right? I have an Audio Control 6XS and I need to get a second one...they have built in line drivers, so I could easily get away with a good 1volt....but why? So long as i like everything else about the deck, you know?

[johnecon2001 82]

I've got a 16v Eclipse I might be willing to be persuaded out of. The CD8053. It would come with the Balanced Line Adapter and the Commander.

[kryptonitewhite 1]

do you find any advantage at...JESUS...16V?? If you had the exact same deck, only at 4V, would it matter?

[johnecon2001 82]

er, probably. That's a 12v difference.

A) you wouldn't have to turn your amp gains up as much to achieve the same output

B) when you keep your gains lower, induced noise is lower as well.

[helotaxi 46]

You'd not be able to use the majority of the volume range with most any amp. Most can only handle 5v. Most only need 0.2v to make full power. Higher preout voltage is only higher with the volume up higher. At higher volume s/n is at its highest anyway and noise isn't audible. High volt preouts are really nothing more than a marketing gimmick assuming that your amps don't have super noisy preamp stages, higher gain settings aren't a big deal.

[kryptonitewhite 1]

For the sake of argument, let's assume 0 noise induction via power wires and rca cables. Gain full for .02 VS gain minimum with 5V. The 5V won't be cleaner?

And since 0 noise induction is impossible, won't 5V still be preffered then?

[helotaxi 46]

Zero audible noise induction is normal. There is thermal noise, it will be far below audible even with 1v preouts. Try this: once you have everything installed again, turn the HU volume almost all the way down (2-3 on the volume control) and turn the gain all the way up. If you can't hear noise then you don't have anything to worry about. I've got a 2V Alpine and my system was dead silent as far as noise goes. More HU voltage would have been totally pointless.

[kryptonitewhite 1]

Alright, between the 2 threads, I'm convinced

That makes shopping so much easier.

[sqguy 0]

That is also assuming the HU has a clean signal at max output voltage; that it is a usable signal. I have run many 2v HU in many vehicles and never had a problem with noise from anything RCA related....even with power wires right next to the RCAs. The only one I recall were the ancient pioneer HU that had half or less than 2v, they would get noise in them. But back then in the 80s either the equipment was not as good or the cars were noisier, because everything had more noise problems than today. Of course most of it was in power wires not RCA. Now I run the power and RCA down the same side of the car in my daily drivers, why bother separating them as it does not matter. If I detect noise I'll move them.

On the other hand many times I have seen a line driver improve the SQ of a system at high output due to inaudible distortion/noise in the HU at high volumes....could not tell until the driver was in and it went louder/cleaner. The HU had been setup to max out at something like <2/3 volume, what was thought/tested to be well into the clean zone of its output. Not a junk HU either.

My Alpine 2v seems to work fine, though I was thinking of trying a line driver just to see what it does. Right now I am pretty sure my amp is giving out since I have run other amps higher volume on the HU and they were still clean.

I have tested some amps on an older early 90s sony HU, not sure of voltage, and they do not have enough gain to go loud (could not set it to max at ~2/3 HU volume). One was a dual xia460, another a sony 2002gtr. So I would look for a 4v minimum HU if I were shopping, but if a nice 2v was there I would have no problem taking that as I have plenty of amps that will work with it. Unless you need it higher for SPL uses, I would not know much about that as I don't use 2Kw &+ amps.

[helotaxi 46]

As long as the HU output is unclipped and undistorted at a voltage level that will allow you to get full power from the amp (like I said earlier most decent amps only need 0.2 v to make full power and pretty much any HU can do at least 1v cleanly) then the max preout voltage is not important at all.

The biggest difference in noise rejection in modern systems have come as a result of a change in amp input design, not anything to do with the HU at all. Good power input filtering to get rid of power line ripple coupled with differential inputs make for a pretty well noise proof system.