DIY: Testing/Measuring the true power output of your Amplifier. Hello guys,
Its not been long since I've join the t-bhp team and I cant express even partially how beneficial this site has been to me and how much info I've gathered already. Going through various threads, product discussions and also the pics of what many of you people have done has given me a hell-lot of new ideas for my car. I'll be posting another thread for that in the appropriate section when the time comes, however for this section, I've come up with a new DIY for all you enthusiasts who'd find it interesting. As the topic says, its about testing the power output of your amplifier.
Almost all brands have been categorized as either over-rated or under-rated. However, this is a mild expression cause we do not know for sure. Moreover, all the amps that have been rated to a specific power level, have been done so in an ideal condition - an ideal power supply (14.4v). Ill be testing many of the amps that I possess, once I'm back to my city in around 10 days, in more of a day-to-day environment (around 13.5v).
I wanted to start this thread to see how many of you people would be interested and also if any of you had ever tried doing this before.
I have already purchased most of the equipment required (except a true oscilloscope, a substitute will be used). In addition to testing the output power, I'll also see if I can get you the frequency response graph for those amplifiers.
The amplifiers I'll be testing are:
JBL - px300.4 - This amplifier is the reason for my experiment in the first place. This amp got me really confused about its power rating after I got my hands of two totally different sets of manuals for it.
The first one - rated to be 75 x 4 (4 ohms), 150 x 4 (2 ohms) and 300 x 2 (4 ohms).
The second one - rated 123.5 x 4 (4 ohms), 169 x 4 (2 ohms) and 358 x 2 (4 ohms).
After spending hours and hours over the internet and talking to as many people as I could over here, I finally found out that the cause of this difference was that the old power rating was not done according to CEA standards, and was tested with a power source of 12v while the later was established with a power source of 14.4v (thanks to CEA). This got me wondering, that maybe I should try to test the amp myself. Another factor that determined me was that the px300.4 has a fuse rating of 60 amps. Now, this is a class A/B amp. And to deliver 358 x 2 at 14.4 volts, it would have to be 82.87% efficient. I have never come across a class A/B amp this efficient. This is what made me conclude that I should test the amp out, to get more clear in my mind and for the fun of it.
Other amps to be tested, for the sake of it:
Pioneer PRS-D4100F
Kenwood KAC-8152D
I have some more amps that I'd like to test, if time permits. But these are the top ones on my list.
Guys, this experiment will be done by me for my own interest. I do not expect any of the amps to be even close to their rated power, considering the sole reason that I will not be testing with a power source of 14.4v, rather in-car battery voltage at idle (not to mention the quality of the tools required - I wont be investing alot as I dont plan on going around and offering amp testing services).
Also, in no way am I doing this experiment to compare any of these brands. Ill be stating the final numbers achieved for all amps, but that is not something that gives an overall estimation of that amp's built. There are many factors which are required to justify an amp's true performance, such as its damping factor, THD, channel isolation, delay etc. which will not be tested by me. So, even if this DIY gives you some additional info about an amp, do not make an opinion based on it.
And at last, testing an amplifier is dangerous - please refrain from trying this yourself, especially if you don't know much about circuits else it could result in test equipment failure, amp failure or even worse, an electric shock.
So now that the disclaimer is over with, lets see what you guys have to say.
Let the fun begin!! |