Cit.wik:
transamguy1977 - 2008-06-06 21:43
Great info!!!
Thanks for sharing Jenz!!!
I've never paid attention to PMPO as I knew it was baloney when my dad (the tech) told me years ago and showed me on an oscilloscope what was really going on.
Good info!
I've never paid attention to pmpo eather it's the
same as that baloney (the wattage output) on the back of boxes, for example a 61 m90 is exactly the same as a 71 watt version, thanks for the info jens.
masterblaster84 - 2008-06-07 17:30
Nice Jens, that pretty much confirms what I already thought.
PMPO = Pretty Much Pretend Output.
its a crap rating, anyone who believes it.....I have some land on the planet venus for you too......
Nice to see that their way of finding the true power of an amp was related to power input.
I've long believed that the power comsumption figure on the back of a b-box is a useful guide to it's sound output capabilities.
This is subjective, however. While I don't have any high power consumption b-boxes that are quiet, there are some b-boxes I own with comparitively low power consumption figures which play very loud (for example the Hitachi 3D7 is rated as only 22W power in).
One other consideration is where the b-box comes from. I have a 3D70 (from Canada or America) with power consumption rated as 60W which is no louder at all than my 3D7. These are a good comparison as they are both single deck & tuner b-boxes with 3 amps for left, right & bass.
When looking at a b-boxes power consumption - don't forget that the tape deck & tuner will use some of that power & if it has a CD player, that'll take some too.
As far as I know, the power consumption figure has to be accurate for the electrical safety standard people & it's supposed to be the maximum possible power consumption of the b-box.
Basically, if it's got "
60W max power output!" on the front & the on the back it says the power consumption is 12W, then you can probably work out for yourself that something isn't quite right
ok i have a Car amplifier with a 80 yes Eighty Amp Fuse so 14.4 V times 80 times 60 percent equals 691.2 watts and its advertised at supposedly well shucks here is the spec's
Here is a rare Alpine MRV-1505 V12 2/1 channel amp. These were the last of the genuine made in Japan Alpines before they went to manufacturing in China. Rated at 1500 RMS watts X 1, they could actually produce quite a bit more.
Here are the factory specs: Max Power (EIAJ) 450Wx2 (4ohm; Stereo) 1500Wx1 (Bridged 4ohm
12V RMS Continuous Power 4ohm; Stereo (0.08% THD) 150Wx2 2ohm;
Stereo (0.3% THD) 300x2 Bridged 4ohm; (0.3% THD) 600x1 14.4V RMS Continuous Power 4ohm; Stereo (0.08% THD) 200Wx2 2ohm; Stereo (0.3% THD) 400x2 Bridged 4ohm; (0.3% THD) 800x1 S/N Ratio 105dBA
Frequency Response 10-50kHz 24dB LP/12dB HP Crossover (30-200Hz) 1-Band Parametric EQ (30-200Hz) Low Impedance Mode Extra Large Gold Plated Terminals with Wire Insert Capability Top Panel Power LED 4 Volt Input Capability Continuously Adjustable Crossovers DC Straight, STAR Topology & Duo-B Circuitry DC-DC/PWM MOSFET Power Supply
ooh, thats a nice 2 channel amp, DM4U.
My Kenwood amp has four 20A fuses, one for each channel.
You'll be going deaf soon, like me
Originally Posted by DecentMan4you:
Here is a rare Alpine MRV-1505 V12 2/1 channel amp. --- Rated at 1500 RMS watts X 1, they could actually produce quite a bit more.
The reason they Alpine gets away with saying the amp delivers 1500 watts is because of a few reasons (of which I'll try desperately to be short)... One, at least in the US, there is no regulation on what legitimate usable (worthy of listening to) sound output rating can be. So upon closer scrutiny of an owners manual you'll see that an amp rates at 100 watts per channel at .9% harmonic distortion might seem 'ok', when what you need to see is what frequency that 100 watt test was generated at.
Cheap amplifiers will give you the same rating, but the sampling frequency will be, say 1200Hz. A commonly known freq that when pushed at the sound pressures I've dealt with can cause rodents to combust.
Another reason amplifier companies (for autos anyway) get away with this over estimation is that they can use the Push "and" Pull of the amplifier as separate readings. Then they just add them together, get a lawyer to slide some legal-ese into the mix to cover their butts add the numbers together & in my example you get a 200 watt amp. Your not supposed to do that because a closed circuit is needed to even get a reading, so how a positive electrical force that "has" to be counteracted by a equal but opposite force can just be added to the total sum? Their using a math I'm not familiar with & probably figure 'Joe Public' will eat whatever feed grain given.
You'd never get away with this kind of BS in the professional market as when engineering 50,000+ watt PA systems there's so much physics involved that a company could be crumbled if they lie about these numbers (subsequent law suits). But in turn, you have to pay for that privileged information. That's why audiophiles get so snooty.
