Does anyone know about Zapco amps? I read that the c2k amps use bipolar output devices. I thought mosfets are better! I know Zapco makes good amps. Maybe I don't fully understand this issue. Could anyone clarify this for me?
They do use mosfet transistors in their power supplies, but the zapco c2k manual states on page seven that "Bipolar transistors are used exclusively in our outputs." This means there are no mosfets in the output stage of a zapco c2k amplifier. As far as I know, mosfet transisters have a much higher switching speed than bipolar transistors. I read somewhere that mosfets can be around 30 to 100 times faster than bipolar transistors in this respect. Wouldn't this mean a higher slew rate? Why wouldn't mosfets be an advantage over bipolar transistors in the output stage? According to the c2k manual, mosfets cause too much distortion (page 7). Yet it goes on to say that distortion levels at the RMS rating in "most modern, high end amps" is not heard (page 10). They also say that "it is probably the least obvious (specification) in normal use." Maybe it's just a personal problem.
MOSFETs are good as a switching device, but not so good for audio reproduction because they are highly non-linear and have high distortion. The reason they are used in power supplies is because they switch so well. In a car, you have to turn DC into AC so that the transformer can step up the voltage, so MOSFETs are used to switch on and off, creating a pulsating DC voltage, and the output of the transformer is turned into AC output and the voltage is stepped up (and current stepped down proportionally, according to the power factor, which is volts x amps), and then rectified back to DC. Bipolar devices are generally better for audio reproduction since they are much more linear and have lower distortion and require less feedback than a MOSFET. MOSFETS have to be given a lot of feedback (sample of output is fed back into the transistor) to lower the distortion to an acceptable amount. The only benefit of the MOSFET in that regard is it's durability and the fact that it can pull closer to the supply rail, with a Bipolar you must use more output devices to get the same level of power, which raises the cost of the amp. They are capable of a higher slew rate, but it's totally useless saying CD Audio has a brick wall filter around 20khz, and the slew rate for a good Bipolar amp is much more than acceptable and can handle anything far past a humans audible range.
Funny, I've heard crazy things about the new line of MTX stuff. Apparently they're going to be able to run off much higher voltage, enabling the current to be less... Smaller wires, etc. One of the tech guys at Mobile Dynamics in Richmond Hill, Ont. was talkin' about it... They should own the market next year.
ya won't find a better amp than the C2K on the market today for car audio in my personal opinion. regarding transistors:
"Bipolar or MOSFET?: We have seen both MOSFET (Metal Oxide Silicon Field Effect Transistor) and Bipolar transistors used in audio amplifiers. Claims have been made that each is superior. I have seen claims that MOSFETs have a tube ("Valve" for the Brits) sound. This is more folklore. The musicians and their instruments are supposed to have "the sound", not audio equipment! MOSFETs are tougher than Bipolars, and can pull closer to the supply rail. It takes more Bipolar transistors to achieve the same power as a MOSFET, therefore Bipolar amps tend to be more expensive. But, MOSFETs are very non-linear, compared to Bipolars and require much more [f e e d b a c k] to achieve reasonable distortion numbers. They are a great choice for bass amps, as low frequency audio is not difficult for a MOSFET. The most expensive car and home amplifiers almost always use Bipolar transistors."
Ok question? should i run my jl 500/1 or my zapco referance 500m class a/b mono amp??? the zapco does 500rms at 4ohms and is underated and can do 538rms and at 2 ohms it can do 700rms. The fuse rating is 40A for the zapco though. Which one of these amps whould be more efficiant if i run it to a avalanche 15 800 watt subwoofer.????? my stock alternator is 80 amps and im also running my ppia300.2 for componants.. and i will use my batcap 800 stereo battery in the back..thanks
the JL 500/1 will in theory draw less current b/c it's a class D amp, but a 40A fuse rating on the zapco would lead one to believe that it also is rather efficient. personally, i would run the zapco, but if you think you'll be short on current, which you will with an 80 amp alternator, then you may have to run that JL. i dont know. this review says the 500/1 does 604 watts @ 12.8 volts into a 2 ohms load, and that the current draw at 1/3 of max power is 26 amps @ 206 watts, however the efficiency of the amp increases as power increases, so it's not like it will need 78A at max power. porbably more like 50A at 600 watts with like an 85% efficiency.
well, the JL has a 50A fuse and the zapco has a 40A fuse, so i would assume that it'll pull less current than the JL. kinda goes against the ole' class D vs class AB thing, but i guess it just shows how efficient zapco amps are. my memphis amp is crazy efficient also. just one more reason to buy quality amps i guess.
how many threads are you going to spam with these same questions over and over again, MO? It's really starting to get annoying, man. asking once is plenty. just be patient and wait for an answer. It seems like every thread I open has your question about JL and Zapco amps in it.