Checking Output ?

[snush]

How can the output of a amplifier be checked ? If it's advertised to be 250 amps., how can we check that thats what we are paying for ?
SNUSH

[Tdubliture]

How can the output of a amplifier be checked ? If it's advertised to be 250 amps., how can we check that thats what we are paying for ?
SNUSH

250 amps! Holy s&$@! Lol you probably mean watts. You can check the current draw of the amp with a multimeter when it is at your max listening volume (can't be held accountable for blown speakers! Stop when is starts sounding bad) now times that by your voltage and that is your consumption wattage. Now as for wattage at the outputs? It depends how efficient your amp is. Prob around 50-60%.
250 watts also may be the advertised max output. Rms wattage is a better measurement as far as comparison go.

[snush]

OOP's Yes I meant watt's. How can RMS wattage be measured ?
SNUSH

[rtoledo]

OOP's Yes I meant watt's. How can RMS wattage be measured ?
SNUSH

you need specialized instruments and training to do it. besides it's the noise that matters most so so amplifiers start to sound like crap past 75% of rated max. good amplifiers like the Harman Kardon use LOW wattage ratings that beat others with 100 more watts, and the HK stay clear and crisp all the way to -0 (max) and past it


In mathematics, the root mean square (abbreviated RMS or rms), also known as the quadratic mean, is a statistical measure of the magnitude of a varying quantity. It is especially useful when variates are positive and negative, e.g., sinusoids. RMS is used in various fields, including electrical engineering.
It can be calculated for a series of discrete values or for a continuously varying function. The name comes from the fact that it is the square root of the mean of the squares of the values. It is a special case of the generalized mean with the exponent p = 2.


here's a couple of links on noise measurement and cancelation

http://users.tpg.com.au/users/ldbutler/AmpNoise.htm

this one is used on things like the LNA in BIG DISHES like the ones for tv transmissions to space and back on the ground

http://en.wikipedia.org/wiki/Low-noise_amplifier

[snush]

you need specialized instruments and training to do it. besides it's the noise that matters most so so amplifiers start to sound like crap past 75% of rated max. good amplifiers like the Harman Kardon use LOW wattage ratings that beat others with 100 more watts, and the HK stay clear and crisp all the way to -0 (max) and past it


In mathematics, the root mean square (abbreviated RMS or rms), also known as the quadratic mean, is a statistical measure of the magnitude of a varying quantity. It is especially useful when variates are positive and negative, e.g., sinusoids. RMS is used in various fields, including electrical engineering.
It can be calculated for a series of discrete values or for a continuously varying function. The name comes from the fact that it is the square root of the mean of the squares of the values. It is a special case of the generalized mean with the exponent p = 2.


here's a couple of links on noise measurement and cancelation

http://users.tpg.com.au/users/ldbutler/AmpNoise.htm

this one is used on things like the LNA in BIG DISHES like the ones for tv transmissions to space and back on the ground

http://en.wikipedia.org/wiki/Low-noise_amplifier

[rtoledo]

Sorry I know it's a lot of mumbo jumbo. bottom line always look at the the noise the amplifier puts out. the watts is VERY misleading.I learned that the hard way.
here's a Harman Kardon HK990 I own and the specs, as you can see the RMS can vary by the impedance of the speakers you use, but the real important thing is the LOW 0.03% of noise produced by the amplifier. that's pretty good. notice the weight of the AMP ? it's 43lbs.

Stereo Integrated Amplifier: The Harman/Kardon HK 990 is a powerful stereo integrated amplifier rated at 150 watts of power per channel. The Harman/Kardon HK 990 also boasts an impressive list of advanced performance features; such as fourth-generation Real-Time Linear Smoothing (RLS IV), EzSet/EQ for room optimization, dual subwoofer outputs, and a high-current, ultra-wide bandwidth design for clear sound & more precise imaging. The HK 990 stereo integrated amplifier offers six analog stereo audio inputs & four digital inputs to ensure optimal compatibility with various audio signals.
High-Current, Ultra-Wide Bandwidth Design: The 150-watt HK 990 stereo integrated amplifier outputs a cleaner, louder, & more powerful sound thanks to its high-current, ultra-wide bandwidth (10Hz-10khz) design. By utilizing something called high-current capability (HCC), which provides the instantaneous current necessary to precisely drive & control nearly any loudspeaker system, the HK 990 can accommodate more headroom during dynamic program peaks, influencing tighter bass & a superb transient response at any volume level. The Ultra-wide bandwidth amplifier design offers improved transient accuracy & phase linearity.

Watts RMS per Channel (8-ohms)	150
Watts RMS per Channel (6-ohms)	220
Watts RMS per Channel (4-ohms)	300
Frequency Bandwidth	20-20K
THD	0.03%
Impedance	8 ohms
Signal to Noise Ratio	100
Discrete Outputs	Yes
Number of Inputs	8
Phono Inputs	2
Preamp Outputs	4
Width (inches)	17-5/16
Height (inches)	6-7/16
Depth (inches)	18-11/16
Weight (pounds)	43.2
Parts Warranty	2 Years
Labor Warranty	2 Years

[gregvan]

Snush,

I don't know how to measure output of an amp but when I'm wondering about this same type of thing I look for the rated watts RMS and THD.

I dig around the vendors website and try to find RMS and THD it in the "specification" section. If not there you might have to call them as I did one time and actually got a response, was shocked. I think you want THD less than 1%.

The chart that rtoledo posted above you can more or less ignore for what your looking at. Those specs are insanely awesome (maybe the best I've ever seen) so don't go into it thinking you'll find a similar chart on your amp and compare it to the chart above because I would guess 99% of the amps out there will be worse than what is shown.

[VTXHOGG]

Advice from someone semi-deaf, ex-audio guy:


If I was looking to spec’s on paper to decide what sound system to buy for my X, #1 the system needs to be Efficient, you have a small budget for power.

I would look at speaker efficiency. This is how loud the speaker is at 1 watt @ 1 meter.
Referred to as "Sensitivity"; Higher the “db” the better. The sensitivity of the speaker important as it will take two times the power out of you amplifier to double the speaker output 3db (loudness), this means that a speaker with sensitivity of 92db @ 1W will be 95 db @ 2W, 98 db @ 4W and so on… If a speaker with sensitivity of 86db @ 1W will be 89 db @ 2W, 92 db @ 4W, and 95db @ 8W.

On the Amp it’s the type (class) of that determines efficiency. Class of amplifier has to do with the design and how it accomplishes the amplification. The three basic Audio classes are “A”, “AB” & “D” there is also some hybrid classes too. But most common in automotive audio are “AB” and “D”. Class D amplifiers are the most efficient and should be considered for a motorcycle system.

That said; I would not buy a system only on published spec’s. Everyone’s ear is different [TRUST IT] listen to systems and your friend’s insights. Read reviews sound like you have a good start.



Good luck, and keep us posted.

[kodiak536]

Being an electronics tech that actually got a worthless degree to show for it, I always look for the RMS output versus the peak.

They can "claim" 500watts of output but, it'll be pure static at best.

I'd rather have 100Watts of pure RMS sound any day.

If you know the load resistance(speakers, etc), you can calculate the estimated out put.

To measure it, you'll need some equipment and knowledge.

But, why bother? If you already haven't been "suckered" into buying these so called high output amps, go get a good RMS output amp, NOT peak value.