Gain: Less 'Is' More

[NorthQuad]

I've just read Mikes, "How to Set Amp Gains with a DMM (digital Multi-meter)" and feel like punching myself in the balls. I've never known what Gain was truly meant for until today. All I knew is that turning this function up too much made the subs and speakers sound like dirty bum crack, if dirty bum crack had a sound that is.
So now with more knowledge comes more questions. I've been trying to figure out the equation to find the voltage power output using this formula of Mikes. But I'm left scratching my head.

- Take the RMS wattage per channel and multiply by speaker(s) ohm load
- Now take that number and push the square root button on the calculator
Example: 50 Watts RMS x 4ohm load = 200, square root = 14.142135
So the voltage reading for our example on the digital multi-meter should be 14.1

The Kicker amp I'm using to power the two Comp VR subs is a 600.1, which I'm told by Kicker support pushes 700 RMS at 2ohm. The two Comp VRs are wired to run at a 2ohm load. So the voltage power I find using the calculator following the formula = 37.41657 using the 700 RMS rating. At the 600 RMS rating I get = 34.64101. I'm not sure which RMS amount to follow. And I'm not even sure the voltage amount is correct. Am I royaly screwing up here?
I have more questions to follow but I just ran out of fuctioning brain cells for the moment.

[NorthQuad]

Here's where you can find the entire "How to Set Amp Gains with a DMM" thread.

http://www.caraudiocentral.net/forums/s ... php?t=7686

[NorthQuad]

Also, would it help to know the HU specs? Is it possible to set the gain on the amp(s) without having to use a multimeter and going by HU specifications alone?

I found the manual for my deck on the Panasonic site in PDF form. I tried posting the link but it wouldn't work.

[JeremyC]

Also, would it help to know the HU specs? Is it possible to set the gain on the amp(s) without having to use a multimeter and going by HU specifications?

Yeah its possible, but I don't recomend it. There are to many variables. At what point does your head unit clip? What is the output voltage when the volume is kept below clipping? Are all of your outputs the same (eclipse isn't)? At what point is the input stage truly set at 2 or 4 volts?

Honestly if your not going to set your gains with a dmm, or o-scope, you probably better off doing it by ear.

Edit, oh I just looked over your math, and it all looks right. As for which one to use, I would try them both. As long as kicker is correct, your not going to exceed the operational capabilities of the amp. So give them both a shot and see which one you like best.

I'm sure cargodz put this in his post, but I'm going to say it again. Make sure you turn the volume on your deck down when you do this. Most decks can't run full tilt without clipping some of the output stage. So make sure you turn it down some, or have someone check it with an o-scope to see were it starts to clip.

[NorthQuad]

Thanks, Jeremy. I need to go buy a meter than. It's only twenty bucks at Radio Shack and I'm sure it will pay for itself anyway.

I have a good ear and I would be able to set the gain 'properly' now that I understand what it does and why it changes the sound. But why the heck not confirm that it's set properly with a quick check of a DMM? It's totally worth the assurance and peace of mind.

The budget I set for myself on my recent system upgrades have been completely thrown out the window anyway, so what the hell. I've spent a grand instead of the $500 I planned on.

[NorthQuad]

I understand every part of Mikes guild but one part.

This...

Remove positive wire speaker wire from the amp (while some say this is not necessary, I recommend so as not to accidentally cross the positive and negative wires)

Do the subs/speakers need to be hooked up for this test at all?

[Bwcad1]

If you really want to get test it get a clamp and a multi meter. and i can give you the formula to calculate actual wattage and reactive load. which by then you can test for clipping.

[Bwcad1]

I understand every part of Mikes guild but one part.
This...
Do the subs/speakers need to be hooked up for this test at all?

i would never unhook one of the leads on the sub your not getting the gain correct then because there is no load.

[cargodz]

No they don't need to be unhooked for this, and I never unhook them... It is in some cases just a precaution... And if you've got a Harbor Freight Tools nearby, you could save yourself at least 10 bucks on that meter over radio shack.

[Bwcad1]

just a precaution to what? leaving them hooked up is just as safe?