Gain With DMM Clarification

[venoxcide]

I just want to make sure I'm doing this properly.

I'm using a Kicker CX1200.1 for my bass amp at the moment which mine's claimed RMS output is 1276W @ 2 ohms. (as per the certificate they include in the box)

I'm connecting a pair of Pioneer TS-W304Rs which are SVC 4 ohm subs rated at 300W RMS each.

They're in a fairly small sealed box so I'm wanting to give them 400W RMS each for a total of 800W RMS.

I know so far the signal coming from the head unit is clean and I'm using the Bass EQ knob on the amp about 2 notches up. It's maybe 1/6th of the way turned up. I'd rather do my EQ outside of the headunit and amplifier but I don't have a sound processor yet. Maybe in the future.

Using an Ohms law calculator, I should be targeting around 40V on the DMM correct? That should equal 800W and should split to 400 each per sub.

This is how I have it set right now and I've done about two hour long straight play sessions yesterday with some very heavy bass songs including some Decaf songs and the subs aren't the slightest bit hot on the cone after those sessions, neither was the amplifier.

The bass as it is now sounds just the way I want it at the level that I want it, so I just want to verify that I have everything setup properly as I don't have one of those fancy o-scopes that also tell you exactly how much watts is coming out of the amp.

Thank you for the help.

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[speedyjuarez Premium Member]

40 is the correct output voltage.

 

[The_Quiet_One 10+ year member]

You have a phase angle that is affecting your total power, but if you're happy where it's currently at it shouldn't be a huge issue. You took the measurement at listening level with a low frequency sine wave correct?

 

[venoxcide]

You have a phase angle that is affecting your total power, but if you're happy where it's currently at it shouldn't be a huge issue. You took the measurement at listening level with a low frequency sine wave correct?

What's the phase angle issue? I'm not sure I know what that is. Is that referring to the 0º / 180º phase of the subwoofers?

And yes a 0db 50Hz sine wave playing on my head unit at 48/62. From what I've researched my head unit (Pioneer DEH-x6700BT) starts clipping at 51/62. I usually listen at a maximum of 40-42.

 

[The_Quiet_One 10+ year member]

No, it's not related to the phase of the subwoofer to which you are referring, that just "flips" the signal.

The ohms law you used is meant for DC. In AC you have a couple factors that give the end result that at any given point inductance, current, and voltage are not in sync so it can throw off your calculations by a bit (up to 30%-40%). In the case of subwoofers one of the biggies is the inductance. If you were trying to eek out all the power out of your amplifier then it would become an issue. Not to mention the clipping introduced by HU or source that someone cannot see with a DMM. I only mention it so any future readers will know it's not quite cut and dry as using Ohms law, but again in your scenario and with your previous research and listening habits I seriously doubt using the DMM method will adversely affect your equipment.