Multimeter readings

I've been having problems troubleshooting my setup. I can't seem to figure out what's causing my low power. Here's my setup: Alpine CDA-7998, (4) 4" MB Quart RKC110, Soundstream VGA800.5 amp, (1) JL 12w6v2.

Can someone tell me if anything I did below was carried out wrong?

Checked sub VC using multimeter in ohm mode....it read 2ohms.

Checked RCA's output at HU in ACv mode...it read 1.2v for each plug, shouldn't it be higher because they're suppose to be 4v preouts? Or is that 4v combined output per pair of preouts? My subwoofer preout reads 1.2v only if I turn the subwoofer phase 0 degrees to +15...if I turn it down to 0 it reads .2v. So does that mean it has to be at +15 to achieve the 4v Alpine rated them at? Is there something wrong with my HU?

I popped in a new test CD I made the other night to try to set my gains....my amp should put out 400x1 @ 2 ohms...my sub is wired in parallel so it's impedance is 2ohms...so I took the square root of 800 which is 28.28v....that was what I was trying to match. I popped in a 50hz track and turned my HU to 3/4 of it's max....checked the ACv reading from the sub speaker output of the amplifier...it read 44v...changed the track over to a 100hz track and the reading went down to 6.3v.  What's going on here?

As for my coaxials....the amp is rated at 50x4 @ 4 ohms...so I took the square root of 200 which is 14.14v...I hooked up the multimeter and it read 19v per channel. Isn't that a little high?

When setting gains I should turn the subwoofer volume on the deck all the way down to 0 shouldn't I? If I have it at 0 then I would have to turn the gain on my amp all the way up to only get 24.4v. The thing that has me stumped is howcome my voltage readings are nowhere close to each other at different frequencies?

Please point out what I did wrong or if anything is wrong with my system. Thanks.

The sound signal is an AC signal continously changing in frequencies and amplitudes.

You will not see the same AC voltages all of the time. The coil's impedence depends on the frequency of the signal applied.

Enough of the electrical engineering...how does it sound?

So how do people check amplifier rms and set gains using a multimeter?

It doesn't make sense to me why the multimeter reads 44v (968w rms) @ 50hz and with the exact same gain setting and HU volume it reads 6v (18w rms) @ 100hz.

Low bass.

Is it a five channel amp? Tri mode exists in 2 and 4 channel amps, exceptions to everything though ... Let me know . By the way, Replace it regardless, start off with the new if its for free ... oops, i just remembered, nothing in this world is free (Except laughing at people who buy Pyle audio)

Yes, its a 5 channel amp.

I just wanted to make sure that it's actually the amp that is at fault and not me. (It's going to cost me to ship) so I just want to be positive and not waste my money and the sellers time if it's not needed. How should I check it? Thanks.

100hz for sub and 250hz for coaxials.

Is my HU okay? Are those the correct readings for preouts?

The deck manual.  Try this:  with sub amp gain set all the way down, read AC output voltage at the amp's sub speaker terminals.  The deck should provide 4 volts input and you should read just about that with a proper test tone at about 50 Hz and 100 Hz.  I can't tell by reading through this overly-complicated manual, but I think the sub control might be an attenuator control and not a boost control.  If 0 setting is the lowest point of the control, then the sub output might be severely attenuated.  Try adjusting that control on the deck to a higher level until you read 4 volts at the amp.  Then adjust amp gain to get the desired output voltage.

The sub output of the deck should be set to Stereo, which is the factory default setting.  The signals will become Mono at the amp.  You can also play with this setting to find the best results.

And, as you were told in the thread about this subject you posted earlier...when you are not using a verifiable true quality test tone recording, the results you find may not be accurate.

Thuan] wrote:

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00hz for sub and 250hz for coaxials. 

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The reason your voltage output is lower at 100Hz, then, is because the crossover is cutting the output at that frequency.  That's what it is designed to do.  The reason you are reading 44V at 50Hz is you input gain is set too high.  You need to set the gain properly, IMO. 

Alright this is what I did earlier today:

Set sub gain with a 50hz track to 28.28v....when I switch the test cd to a 100hz track with the same gain setting at 50hz the voltage drops to 5v...it should stay close to 28v at 100hz right? I have the LPF set to 120hz so none of the frequencies should be cut off.

As with my coaxials....I popped in a test cd of 1khz, set gains to 14.14v...switched it over to a 2khz track...the reading remained at 14v. So everything seems fine with the coaxials but it's just the subwoofer that's giving me big differences in readings.

As for the RCA's I did what stevedart told me and these are my readings:

With my volume on the HU at 3/4 max and gains all the way down, I get 3.9v. If I turn the volume to max, it shows 9v (is that right?). These readings were stable regardless of frequency.  

For the subwoofer setting on the HU I turned it from Mono back to Stereo...it sounded a little better but maybe I'm just imagining that. I switched the Media Expander feature on my HU on and it made everything sound 5 times better...is it okay to use this feature?

I also turned down the subwoofer setting from +15 to 0....I think you were right about it being an attenuated...the readings on the multimeter went from 3.9 @ +15 to 0.5v @ 0.

Is there a reason why I am supposed to set gains using a 50hz test track? I have my subsonic at 25hz....is this even at the right place?

Thanks for being so patient. Hopefully you guys haven't gotten fed up with my questions yet.