I would like to buy a Car Amplifier. around 750Watt 2 channels. Is there any recommendation ? Price ?
I think Pioneer GM5000-T is quite good. any opinion ? Also I what else can I look at ? I am just a n00b in car amplifier. It would be very kind if someone can give some professional opinions.
TAROT Wo
Unregistered guest
Posted on
It is cheap. US$99. but for car audio I think Pioneer is not good enough. The design is boring.
That amplifier is really only 380 watts @ 2ohm(4 ohms bridged) RMS. Don't pay attention to any of those "peak" or "music" or "dynamic" power ratings. They don't mean much. Look at the RMS rating when choosing an amp instead.
For a little more(than $99) you can get something with about the same power thats gonna sound a lot better. I'm not too familiar with Pioneer amps, but hey, 380 watts(125 x 2 @ 4ohms) ain't too bad.
I guess it all depends on your budget, but whenever, with a few notable exceptions(MTX), I see a manufacture rating an amplifier with peak, music, or dynamic power I automatically become skeptical of their product. What, are they embarassed of their RMS rating? There's no need to "cook the books". Cmon.
-Fishy
HKC
Unregistered guest
Posted on
Thank you very much for your replied. But can you please explain more about the RMS rating. What is that about ? How come it does not give out in the spec normally.
Also what other area do I need to look at when chosing a Car Amp ? What is the price depending on ? ( not the max power, No. of channel? )
RMS stand for "Root Mean Square". The voltage/current required to produce musical output is of the alternating(A/C) variety which has peaks and valleys. When voltages to determine power output are measured in a/c circuits the instruments used are usualy calibrated to read RMS values which is kinda like the average voltage. The average voltage over a cycle is actually 0 since its spends the same amount of time/distance above midpoint as below. To get rid of this negative part you square both sides of the sinusoidal voltage equation, use a trig identity, and then take the sqaure root again which gives you "Vrms is equal to the squareroot(ROOT) of the average(MEAN = divided by 2) of that voltage that was squared(SQUARE)" or
Vrms = ((v^2)ave)^1/2 = (v^2/2)^1/2
Once you get the RMS values of voltage you can use them with your basic DC equations like P=I*V and V=I*R to figure out the average power of an alternating electrical system.
There's nothing magical about it. The only thing thats probably worth remembering is that an RMS quantity is simply that quantity's peak amplitude divided by the squareroot of 2.
What gets me mad about these peak ratings is that they don't refer to peak voltages or currents, but to power that can be delivered for a short period of time. Thats awfully darn subjective if you ask me. I mean the RMS Power rating is confusing as it is. There's actually no such beast. Power dissipated is power dissipated. All that RMS stuff means is that RMS voltage and/or current measurements, along with a load were used to determine a power rating. If these guys are talking about "peak" power over a short period they could be using an RMS rating for that as well.
I sure wish someone would explain how some of these companies arrive at these "peak" ratings. I swear some have gotta be making them up as they go.
-Fishy
HKC
Unregistered guest
Posted on
Please help to answer this question by Fishy
'I sure wish someone would explain how some of these companies arrive at these "peak" ratings. I swear some have gotta be making them up as they go.'
Don't bother trying to understand peak ratings. They are usually unrealistic numbers that, in theory, are correct but rarely happen.
RMS power is what you want to remember and go by. Know what your speakers/subs RMS rating is and get an amp to match it.
As to Pioneer - I used to use pioneer amps and never had a complaint with them. The company overrates them a little but I suppose that is okay. That was ten years ago though. I have no idea what their new stuff is like.
Fishy: You'd have to be able to trace the schematic of the amp in order to figure out where they get their numbers (assuming they aren't pulled out of thin air) Remember that a lot of marketing people aren't elect. engineers and engineers typically have no use for marketing people (see Dilbert for a more accurate description of the relationship between engineers and marketing peoples). Most likely the marketing people asked the engineers what the peak power was and the engineer gave them some vague answer in techspeak and the marketer said ... yeah .. thanks.
Of course, as a programmer I get extreme satisfaction out of seeing the marketing person leave with a dazed look after explaining how the software, I just wrote, works.