Clamp Numbers... Something wrong?

[Volvowith18psi 10+ year member]

So, I finally got my hands on a Fluke 336 Clamp/ Volt "True RMS clamp meter" and while on break at work, I went to clamp the old Kenwood KAC9105D and well, Im not impressed... Maybe I did something wrong...

I pretty much followed this guide How To: Set your Amplifier Gain - SSA Car Audio Forum to check my gains while out there.

Use their Formula for my Sub Kicker L5 12" 600RMS so I used this: sqrt(600x4)=48.9V... Hopefully that was right.

Anyhow, The audio shop had the thing set upwards near 60v!

Now, I clamped roughly 12-12.5amps and between 44.8/44V, in which VxA=W a depressing 560 @50Hrz tone...

Now, I was mad the amp was doing half the rated 900rms it claims to do, so I cranked the gain to 60, and the amps BB up a lil bit.... The numbers pretty much didn't change.

Why is it so low? Im mean, HALF the rated power, really? Did I screw up the test?

I did check that guide again, jus to make sure, and then I saw to use the 45hrz tone w/ amps BB on, does the 5hrz really make a difference? Is the Kenwood really THAT crappy? WTF, kinda feel robbed honestly.... Any thoughts?

Side thought, out of curiosity, I could in theory clamp the power wire on full load to check amp draw, yes?

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[LosIsATool 5,000+ posts]

Thats at 3.6 ohms. Thats about right.

 

[CAT MAN 5,000+ posts]

So, I finally got my hands on a Fluke 336 Clamp/ Volt "True RMS clamp meter" and while on break at work, I went to clamp the old Kenwood KAC9105D and well, Im not impressed... Maybe I did something wrong...
I pretty much followed this guide How To: Set your Amplifier Gain - SSA Car Audio Forum to check my gains while out there.

Use their Formula for my Sub Kicker L5 12" 600RMS so I used this: sqrt(600x4)=48.9V... Hopefully that was right.

Anyhow, The audio shop had the thing set upwards near 60v!

Now, I clamped roughly 12-12.5amps and between 44.8/44V, in which VxA=W a depressing 560 @50Hrz tone...

Now, I was mad the amp was doing half the rated 900rms it claims to do, so I cranked the gain to 60, and the amps BB up a lil bit.... The numbers pretty much didn't change.

Why is it so low? Im mean, HALF the rated power, really? Did I screw up the test?

I did check that guide again, jus to make sure, and then I saw to use the 45hrz tone w/ amps BB on, does the 5hrz really make a difference? Is the Kenwood really THAT crappy? WTF, kinda feel robbed honestly.... Any thoughts?

Side thought, out of curiosity, I could in theory clamp the power wire on full load to check amp draw, yes?

this is why i never reccomend clamping amps. people dont understand box rise and how different boxes/freq's effect power. what you have was done right now go put your gains back where they should be

and you did that power at 3.7 ohms //content.invisioncic.com/y282845/emoticons/fyi.gif.9f1f679348da7204ce960cfc74bca8e0.gif not too shabby....

 

---------- Post added at 03:50 AM ---------- Previous post was at 03:50 AM ----------

 

Thats at 3.6 ohms. Thats about right.

 

[Volvowith18psi 10+ year member]

Ok, Help me out here. Im not quite sure what that 3.6ohms thing means, like, not at all, what is 3.6 ohms? How to I equate my gain setting then if that sqrt(600x4) formula is wrong? Im just trying to learn here, so I don't have to pay people 60/hr to do this for me.

I cant go back and put them back, because I don't remember what the thing was when I started lol.

Edit: Ok, I see, the 3.6ohms is the "box rise" which still doesnt do anything for me... Trying to learn here, Trying to learn...

 

[CAT MAN 5,000+ posts]

Ok, Help me out here. Im not quite sure what that 3.6ohms thing means, like, not at all, what is 3.6 ohms? How to I equate my gain setting then if that sqrt(600x4) formula is wrong? Im just trying to learn here, so I don't have to pay people 60/hr to do this for me.
I cant go back and put them back, because I don't remember what the thing was when I started lol.

3.6 ohms is the final resistance your amp is seeing while playing 50 hz. your amp is rated at 2 ohm and 900w.

the formula is correct. just dont worry about the numbers it put out in the clamp and set it with an o-scope or with a dmm .

clamping is confusing and frustrating for a beginner. Mainly because they never see the number it was rated at. There are many factors in it. All in which should never be worried about for a regular daily setup. Just go on like you never clamped it //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

 

[DaveVT 10+ year member]

3.6 ohms is the impedance. Your amp will put out around the 900 IF its seeing a 2ohm load which it isnt. Go here to figure voltage needed.

Wattage

 

[Volvowith18psi 10+ year member]

ok, So... I guess the shop did have it rightish. Checked out that site. I assumed the calculator meant MAX(1800w) and not max RMS(900)... which is right around 60v. Guess Ima have to steal this Fluke from work tonight

Few other questions: Using that website, I saw to turn all EQ stuff on the deck to 0, np... I assume this goes for the bass boost on the amp also? Set @ 60v, then turn the BB back on on the amp?

For curiosity sake... How do I make the amp see 1 or 2ohm? Single 4ohm DVC wired in parallel if that helps..

 

[Mitch86 5,000+ posts]

Set the gain using the tutorial and leave the bass boost OFF. You're sub is wired to 2ohm, but with box rise its at 3.6 ohm. Every box will have a different rise etc...really nothing you can do about that.

 

[MANTI5 10+ year member]

Don't turn on bass boost at all.

 

[Mitch86 5,000+ posts]

Btw, the wattage you came up with for 3.6 was actually right on par with the ratings..so the amp would most likely do rated at a true 2ohm load.

 

[Volvowith18psi 10+ year member]

Don't turn on bass boost at all.

I never have the HU's BB on ever. However, while I was playing around with the clamp / DMM, I turned it "off" on the amp just for shits n giggles, and the sub hardly made any noise / barely any bass @ full volume, so I turned it back on...... What gives?

You guys concur the 60v is prime for my gain?

 

[CAT MAN 5,000+ posts]

I never have the HU's BB on ever. However, while I was playing around with the clamp / DMM, I turned it "off" on the amp just for shits n giggles, and the sub hardly made any noise / barely any bass @ full volume, so I turned it back on...... What gives?
You guys concur the 60v is prime for my gain?

dude bass boost on the amp and headunit is bad. turn it off. 60v is what you need but bass boost is bad. you will kill your sub using it.

 

---------- Post added at 05:03 AM ---------- Previous post was at 05:02 AM ----------

 

actually no i just did the math 60v is way too high. you need 42.5

 

[Volvowith18psi 10+ year member]

dude bass boost on the amp and headunit is bad. turn it off. 60v is what you need but bass boost is bad. you will kill your sub using it. 

actually no i just did the math 60v is way too high. you need 42.5

I been beating on it for 2years with the BB turned on on the amp, still going ok AFAIK lol. Not sure why I get like 0 sound without it with everything wired correctly....

The calculation is also where Im confused. One guide says to use the RMS of the lower of the 2 in the system (Amp or sub) in my case, its the sub rated @ 600w RMS. So doing that math, sqrt(600rms X 4ohm DVC??) = like 48.9v. Which is what I set it on.

The guide linked in here uses the formula, I guess, sqrt(1800 MAX W x 4ohm) = 60.... You told me 42.5, so now I'm really confused lol.

Other question: Is minimizing box rise something I should get with my box builder about, or it just kinda happens no matter what?

I really just clamped it to test the hype around here that "Kenwood" amps are junk and don't do rated, which I guess we proved that wrong?

Starting to work a new system together, and since these amps DO do rated, I can also "strap" them and double my power for super cheap (150 bucks) vrs 400 for a new amp.... Just kinda thinking out loud on the straping idea....

 

[CAT MAN 5,000+ posts]

I been beating on it for 2years with the BB turned on on the amp, still going ok AFAIK lol. Not sure why I get like 0 sound without it with everything wired correctly....
The calculation is also where Im confused. One guide says to use the RMS of the lower of the 2 in the system (Amp or sub) in my case, its the sub rated @ 600w RMS. So doing that math, sqrt(600rms X 4ohm DVC??) = like 48.9v. Which is what I set it on.

The guide linked in here uses the formula, I guess, sqrt(1800 MAX W x 4ohm) = 60.... You told me 42.5, so now I'm really confused lol.

Other question: Is minimizing box rise something I should get with my box builder about, or it just kinda happens no matter what?

I really just clamped it to test the hype around here that "Kenwood" amps are junk and don't do rated, which I guess we proved that wrong?

Starting to work a new system together, and since these amps DO do rated, I can also "strap" them and double my power for super cheap (150 bucks) vrs 400 for a new amp.... Just kinda thinking out loud on the straping idea....

Gain Setting Tutorial - eCrack.net /thread //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[madcad95 10+ year member]

I have a maxxlink and if used properly bass boost can be a good thing (IF USED PROPERLY) lol.