Preout voltage low?

[Dangrebel 89]

Hey guys!!! I bought an alpine cde123 and it says it has 4v preouts before clipping. Well I am wondering why when I measure at volume 23(at 24 the speakers start to distort) it only measures .188v, I had to max my amp gain out to get it to play full tilt. Even the the amp clipping light doesn't come on when it's up all the way? What could be the cause of this?

[Julian 641]

You have to play a steady tone to measure voltage

[Impious 1,476]

Was the DMM set to DC Volts instead of AC Volts when you measured the outputs?

That or the HU is not functioning properly.

Are you sure there weren't any settings in the HU that were adjusted in a manor that would negatively affect your measurement?

[Dangrebel 89]

I played a 45 hz tone. And I had the sub level set to +15 which is 0db and eq was flat.

And it was set to ac volts lol I checked it 10 times

Edited January 14, 2012 by Dangrebel

[bassahaulic 155]

If it was that low you'd never have sound output. Lol

[Impious 1,476]

Some amps can produce full output with as little as .2V input, so if he was playing a tone entirely possible he was able to get full output from the amp with the gain jacked to max. Others go as low as .5V range, so again it would be fairly substantial output from the sub with the gain all the way up.

[bassahaulic 155]

Some amps can produce full output with as little as .2V input, so if he was playing a tone entirely possible he was able to get full output from the amp with the gain jacked to max. Others go as low as .5V range, so again it would be fairly substantial output from the sub with the gain all the way up.

Playing tones. But wouldn't see output playing music.

[Dangrebel 89]

Oh yea I didn't mention the tone was -10db. But yea it gets loud no doubt. But not once have I ever seen the bassknob clipping light pop on.

[Impious 1,476]

Even with a -10db tone I would still expect to see ~1.4V from the preamp outputs.

Are you sure you had your DMM set on the correct setting? Depending on what range you have the DMM set to it might have been representing a voltage of 1.88V even though it was only showing ".188" on the display.

And yes with a -10db tone the gain is going to need to be set pretty high to get significant output when playing the test tone. On the flip side you get a lot more average power from the amp when playing music compared to a gain setting based on tones recorded at louder levels.

[Dangrebel 89]

Yes, the dmm was set at the correct setting. I checked it all I could and could not find any errors in my testing.

[bassahaulic 155]

Where is the gain set on the amp?

[Dangrebel 89]

All the way too the right. Which is .2v

[Jmac 24]

Well, with a 0 dB signal, that 0.188V is going to be 0.594V theoretically, which is still on the low side. Now, mind you I haven't used an Alpine HU in quite some time, but the last one (CDA-7893, IIRC) I used had 5V outputs and it didn't put out 5V until you hit into the 30s on the volume control (and that was with a 0 dB signal). Just because the internal amplifier starts clipping at 23 volume, it doesn't mean the pre-amp does.

[Dangrebel 89]

That's what I'm hoping. I will be aping my door speakers soon though and will solve my issue hopefully.