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-   -   hmmmmmmmm amplifier gain (https://www.scionlife.com/forums/scion-tc-1g-ice-interior-1647/hmmmmmmmm-amplifier-gain-104791/)

Neothin 06-13-2007 08:57 PM

hmmmmmmmm amplifier gain
 
Setup-
AVIC-D2
NINe.1
NINe.2
eDi6500s comps
2x 10w6v2's

So i finally got around to resetting the gains on my amplifiers this afternoon after neglecting doing it since installing my AVIC.

Previously I was running a stock headunit and a soundgate lineout converter that had 5v preouts.

anyways, the thing that has me questioning... when i reset my gains, i actually had to turn them down to get to the proper voltage. This is weird because the lineout converter had 5v preouts while the D2 only has 2v preouts. I thought because of the lower signal voltage, i would actually have to turn the gains up. I didnt have to turn them down by a little.. the voltage on the sub amplifier when i first looked at it was 64.something! (which really has me worried, because i ran around for a month with the gain set way over what it's supposed to).

all equalizer settings and such were completely flat on both headunits, so that idea can be thrown out.


anyone more knowledgeable than myself care to enlighten me as to why this happened?

Daskid 06-14-2007 05:16 AM

Where did you measure the sub amp voltage?

I guess, having a higher preout voltage only gives you better dynamic range, headroom and much less hiss/noise from the signal for a clearer sound.


The reason for higher head unit output voltage is to combat noise. The vehicle environment is an electrically noisy one.

Your amplifier receives a low voltage from the head unit and increases it to a higher voltage (and current). This voltage is music. The problem is, electrical noise may be present and that too will be amplified resulting in alternator whine, ignition noise, etc. If you turn the amplifier gains down, the electrical noise is amplified less, but so is the music. The higher voltage head units put out more so you can still get satisfactory volume with the power amp gains reduced thus the system sound to noise ratio is improved!

If you do not have random electrical noise coming out of your speakers, then higher voltage head units will not make any difference for your particular installation.

The test for this is to turn the radio all the way down and listen to the speakers with the engine running. If you hear objectionable noises, then turn your amp gains down. If you then can not get enough volume out of your system, consider a head unit with higher output voltage so you can keep the amp gains low enough to stop the noise.
I hope this helps.

Neothin 06-14-2007 07:27 AM

i measured it by sticking the prongs of the DMM into the amplifier outputs

blazeplacid 06-14-2007 12:52 PM

what is the resistance (ohms) of the signal??? I think its 2.2 v @100 ohms?? Possibly that thr 5v was at 1k ohms or higher???

I used to have a Panasonic rated at 6.5 volts @ 50 ohms =)

Daskid 06-14-2007 04:24 PM


Originally Posted by Neothin
i measured it by sticking the prongs of the DMM into the amplifier outputs

Well, I'm kinda confused here...

Your DMM should read a higher voltage output. I don't know if this is what you need to hear and I know that you know this, but wouldn't it be normal to read 64V out of the amp's output? I mean, isn't that the amplified signal? And you didn't adjust the gain when you measured it, did you?

From what I recall, power is directly proportional to voltage; so if you'll make adjustments on the gain (it's basically a potentiometer or a rheostat), the voltage will change and that goes for the power as well. You would have a high voltage output compared to your HU's output because they're just preout voltages.

Your soundgate lineout converter would technically sound better compared to your AVIC-D2.

Again, we might not be on the same page here, so correct me please. :D

Neothin 06-14-2007 06:28 PM

what i'm talking about is voltage comming out of the amplifier.

with a higher input voltage, the gain doesnt have to be set as high. What confused me is that the exact opposite happened. I had a 5v preout LOC need a higher gain setting than a 2v HU preout to get the same voltage output from the amplifier.

Daskid 06-14-2007 07:04 PM

LOL! That's weird. Try measuring the output voltage on the LOC and on the AVIC. The LOC may be rated 5V but then again, it may not really give out 5V.

Neothin 06-14-2007 07:06 PM

i sold it already haha. ah wells, something i guess i'll never figure out :P

Daskid 06-14-2007 07:09 PM

LOL! Yeah, let's just get over it already. :P

But my best best would be on the LOC not giving out 5V.


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