testing the true RMS of an amp

[pimpedout97x]

i heard you need an RMS clamp meter and a DMM to do this? does anyone locally have an RMS clamp meter that i could test mine with? its for my MA 2/4 channel amps, i wanna know what they do on 12v...or is there a good clamp meter and DMM that will give me a true RMS reading that i can purchase? if so, link me to one //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

thanks

Click to read more...

 

[SPL140.2 5,000+ posts]

sears has good ones either craftsman or fluke, i like the craftsman myself it was $30 cheaper than the fluke, this is the one i have http://www.sears.com/sr/javasr/product.do?cat=Electrical+Shop&pid=03482364000&vertical=TOOL&subcat=Multi-Meters%2C+Testers+%26+Accessories&BV_UseBVCookie=Yes

 

[JoshHd6 10+ year member]

sears has good ones either craftsman or fluke, i like the craftsman myself it was $30 cheaper than the fluke

craftsman...//content.invisioncic.com/y282845/emoticons/yumyum.gif.0556df42231b304b9c995aefd13928a8.gif

 

[pimpedout97x]

and thatll give me a true RMS reading?

what all do i need and how do you do it?

my grandmother gets discounts at sears //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[pimpedout97x]

**** the flukes are like 200+ on sears site?

 

[SPL140.2 5,000+ posts]

dont measure with the peak hold button let the system play for like 5 seconds full tilt with no audible clipping and write down the measurements that way, using peak mode will not give you the correct wattage, Using a clamp isnt the best way to test amps but gives you a great idea on the output/input/efficiency and ohms and is as close as your gonna get without a scope.

 

[pimpedout97x]

im confused now lol

 

[thylantyr 10+ year member]

What do you want to test?

1. Do you want to test the amplifier at full power, lowest rated load?

2. Do you want to test how much power the amp delivers into

your speaker at some frequency ?

3. Do you want to test how much power your amp draws ?

If you want to factor distortion into the amp test, then you need some

expensive gear. A power rating without a distortion number attached is

just a ballpark number. ie, if you set a distortion number of 1% THD+N,

and measure power at different frequencies until you hit that distortion reference,

you will find the power is difference across different frequencies.

 

[pimpedout97x]

well heres the deal-

ive made threads on it, no one seems to know the correct answer.

the ma hk598. some sites say:

400w rms x 4 @ 2 ohm

and some say

200w rms x 4 @ 2 ohm

i wanna know if its really 400w rmx x 4 @ 2 ohm. the manual says "RMS per channel" = 400w rms @ 2 ohm

but thats 1600w rms for a 180 dollar amp. seems a little odd, 200w rms x 4 seems more reasonable....but i dont know.

i also wanna see what they do on 12v reguardless.

 

[pimpedout97x]

What do you want to test?
1. Do you want to test the amplifier at full power, lowest rated load?

2. Do you want to test how much power the amp delivers into

your speaker at some frequency ?

3. Do you want to test how much power your amp draws ?

If you want to factor distortion into the amp test, then you need some

expensive gear. A power rating without a distortion number attached is

just a ballpark number. ie, if you set a distortion number of 1% THD+N,

and measure power at different frequencies until you hit that distortion reference,

you will find the power is difference across different frequencies.

1. yes. wanna see what it does per channel @ 2 ohm (rms, not peak)

2. i guess?

3. i dont care about that.

 

[path2spl 10+ year member]

i have the fluke 87V true rms meter can i use this?

 

[SPL140.2 5,000+ posts]

1. yes. wanna see what it does per channel @ 2 ohm (rms, not peak)
2. i guess?

3. i dont care about that.

again the clamp will give you a good close # of the output of the amp, just dont use the peak mode

 

[pimpedout97x]

so that 80 dollar craftsman one posted above will work?

 

[Spac3d 10+ year member]

so that 80 dollar craftsman one posted above will work?

I got that same Craftsman for about $40 on eBay used ... sold it after I was done using it for $55. //content.invisioncic.com/y282845/emoticons/naughty.gif.94359f346c0f1259df8038d60b41863e.gif

 

[thylantyr 10+ year member]

well heres the deal-
ive made threads on it, no one seems to know the correct answer.

the ma hk598. some sites say:

400w rms x 4 @ 2 ohm

and some say

200w rms x 4 @ 2 ohm

i wanna know if its really 400w rmx x 4 @ 2 ohm. the manual says "RMS per channel" = 400w rms @ 2 ohm

but thats 1600w rms for a 180 dollar amp. seems a little odd, 200w rms x 4 seems more reasonable....but i dont know.

i also wanna see what they do on 12v reguardless.

You want to determine whether it's 400w or 200w @ 2 ohms. The poor man's

method without spending coin is to open the amp and measure the power

supply rail voltage using a cheap DC voltmeter. Just turn on the amp with

no tunes playing and try to identify where you can probe the rail voltages.

If you read +/- 50 volts {plus or minus 5v} then it's probably a 400w @ 2 ohm

amp.

If you read +/- 35 volts {plus or minus 5v} then it's probably a 200w @ 2 ohm

amp.

If you don't open up the amp and just connect a 2 ohm woofer, play some

tunes at what you think is maximum power, place the AC voltmeter across the speaker, see what voltage you get. See if it correlates with above.

If you really want to test the amp, then you need resistive loads, scope,

sine wave. This is more work, more money but you can see what the power

is before clipping.

The clamp method is measuring current, but you still need a proper load,

scope, and sine wave. A $5 voltmeter is just as good.