Finally picked up a clamp meter and tested my zx...

[teamsubgopoof]

Where did I ever say I was the only person here with electrical knowledge? Judging from your posts, you don't seem to have a very decent grasp though.
And since when has apparent power ever been a standard for labeling amps?

the reactive load he is testing under is what the amp does in his vehicle.

We can throw 50 different amps on the table, and bench everyone of them on a fixed resistor and get a control test.

throw them in my truck and i gurantee one amp will out perform another, and it will be one different then the fixed resistor tests we did.

I realize you understand about electronics, but do you understand about SPL?

In SPL you are trying to get the most power possible, you tune an enclosure to maniuplate the reactive load of your woofers, to make your amps peak out, reactive load is ALOT more important in the field then fixed resistors and nominal impedence

 

[headless 10+ year member]

I'm confused - did you put the clamp meter around a speaker wire, tommyk? Or the input wire to your amp?

 

[tommyk90 5,000+ posts]

so would i be correct in assuming that if you have a final load of 1 ohm with amp A and a final load of 1 ohm with amp B, that the results can be considered fairly accurate? not in a sense of oh this amp puts out xxxx total watts, but this amp puts out roughly xxx watts MORE than said amp?
just so that we could have something to go on when comparing amps head to head?

See, that wouldn't work either.

If amp a is running at .5 nominal, and amp b is running at 1 ohm nominal (no impedence rise, which is a pipe dream, but just an example), then the results would be skewed still.

Also, you have to remember that different amps are built in different ways. While the zx2500 is a 2 ohm stable based amp, most others are 1 ohm stable.

Thus why it is difficult to compare amps on a bench test. In car tests have the potential to greatly differ from a bench test. Which is why some companies that test amps (like maxxsonics) will say "these are bench tests and in-car performances will vary" or something along those lines.

 

[IgnoreMe 5,000+ posts]

I'm confused - did you put the clamp meter around a speaker wire, tommyk? Or the input wire to your amp?

speaker wire.

input to the amp will tell him how much the amp is drawing, now how much its outputing.

 

[tommyk90 5,000+ posts]

I'm confused - did you put the clamp meter around a speaker wire, tommyk? Or the input wire to your amp?

Around the speaker wire.

Why would I put it around the input wire?

You're measuring OUTPUT of the amplifier, not input (i.e. current draw).

 

[teamsubgopoof]

I'm confused - did you put the clamp meter around a speaker wire, tommyk? Or the input wire to your amp?

you put a clamp around the speaker wire

and probe negative and positive on ac voltage

when you start a burp the numbers will go REALLY high for a second then come back down and level off, you want those numbers

multiply the amperage and voltage together and get "volt amps"

and if you divide the voltage by the amperage you get your actual impedence during the burp

 

[IgnoreMe 5,000+ posts]

See, that wouldn't work either.
If amp a is running at .5 nominal, and amp b is running at 1 ohm nominal (no impedence rise, which is a pipe dream, but just an example), then the results would be skewed still.

Also, you have to remember that different amps are built in different ways. While the zx2500 is a 2 ohm stable based amp, most others are 1 ohm stable.

Thus why it is difficult to compare amps on a bench test. In car tests have the potential to greatly differ from a bench test. Which is why some companies that test amps (like maxxsonics) will say "these are bench tests and in-car performances will vary" or something along those lines.

well yea i figured you would be lucky to find amps that will both match each other on final load. like i said though, i would still do it your way since at least it keeps some kind of a constant in mind.

i got a headache.

 

[Immacomputer 10+ year member]

I want to know actual power that my SUB is receiving, not a completely resistive load.
How do i measure ACTUAL power my SUB is getting by placing a purely resistive load on my amp? Like I said above, theories are all fine and dandy, but they really mean d*ck in the car audio world. There's far too many other factors that come into play.

The actual power the sub is getting IS what would be measured on a purely resistive load. The inductance and capacitance of the circuit fluctuate the voltage and current and it gives the appearance that there is power absorbed. This is NOT the case but it would appear so to somebody just measuring current and voltage.

Like I said, theories do mean "d*ck" in car audio as long as you understand them. If you don't fully know what's going on, it can be extremely difficult to understand it.

 

[headless 10+ year member]

Because, at least if you put it around the input wire you'd be in the general ballpark accounting for efficiency losses... your method is totally fvcked..apparent power is not how you try and represent an amplifiers' output unless you're trying to sell it to idiots at wal-mart.

 

[tapout 5,000+ posts]

i got a headache.

true. true.

 

[IgnoreMe 5,000+ posts]

Because, at least if you put it around the input wire you'd be in the general ballpark accounting for efficiency losses... your method is totally fvcked..apparent power is not how you try and represent an amplifiers' output unless you're trying to sell it to idiots at wal-mart.

what in the hell are you talkin about

 

[teamsubgopoof]

Because, at least if you put it around the input wire you'd be in the general ballpark accounting for efficiency losses... your method is totally fvcked..apparent power is not how you try and represent an amplifiers' output unless you're trying to sell it to idiots at wal-mart.

so how in the WORLD do YOU figure that knowing current draw IN is more important then current out?

and btw EVERY SINGLE WORLD RECORD HOLDER in dbdrag tests power in the voltage x amperage method //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[tapout 5,000+ posts]

where is squeak, audioholic, and helotaxi when you need them?

must be spending thier Friday night somewhere other than in front of a computer screen.

 

[tommyk90 5,000+ posts]

The actual power the sub is getting IS what would be measured on a purely resistive load. The inductance and capacitance of the circuit fluctuate the voltage and current and it gives the appearance that there is power absorbed. This is NOT the case but it would appear so to somebody just measuring current and voltage.
Like I said, theories do mean "d*ck" in car audio as long as you understand them. If you don't fully know what's going on, it can be extremely difficult to understand it.

Theories only bring you to a certain point. In THEORY, doubling the power should add 3 dB. In THEORY quite a few things should always work. Now you and I both know that's hardly the case.

See, a purely resistive load is NOT going to act like a subwoofer. That's a lie. When a subwoofer moves, it generates air pressure, which is going to change the way the woofer acts. Is a resistive load going to do that? No, it's going to sit there and act completely uniform through the entire test.

Not to mention the vehicle itself. Why do you think I get different test results when I brace the car or open a door or window? That kind of shit isn't going to happen on a test bench, yet all of these things can and WILL affect power output.

See where I'm coming from?

Because, at least if you put it around the input wire you'd be in the general ballpark accounting for efficiency losses... your method is totally fvcked..apparent power is not how you try and represent an amplifiers' output unless you're trying to sell it to idiots at wal-mart.

Why the hell would I want to find DC voltage to figure out volt amps (which is AC)?

 

[Immacomputer 10+ year member]

so how in the WORLD do YOU figure that knowing current draw IN is more important then current out?

and btw EVERY SINGLE WORLD RECORD HOLDER in dbdrag tests power in the voltage x amperage method //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

And EVERY SINGLE DESIGNER behind the amps used understands the difference.

Saying amp "x" put up this score with my setup and amp "y" put up that score with my setup is great and an awesome way to look at amps for certain situations. Taking this method to say what kind of power your amp does is just not correct no matter how many people do it and say it's right.