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New member Username: AtomoswavPost Number: 1 Registered: Jan-05 | 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? |
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Gold Member Username: InvainMichigan United States Post Number: 1882 Registered: Aug-04 | They do still use Mosfet. |
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New member Username: AtomoswavPost Number: 2 Registered: Jan-05 | 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. |
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Gold Member Username: Jonathan_fGA USA Post Number: 3592 Registered: May-04 | 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. |
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New member Username: AtomoswavPost Number: 3 Registered: Jan-05 | That cleared things up. Thanks. Oh, BTW how do the new orion amps sound? I know they are not as good as they used to be, but I was still considering the orion 8004. Should I wait for the new MTX amps to come out instead? |
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Gold Member Username: InvainMichigan United States Post Number: 1891 Registered: Aug-04 | I would honestly try the older Mtx amps over the newer ones. As for the new Orion amps, their still not bad, but nothing compared to the first and second generation amps. |
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Bronze Member Username: _andrew_Post Number: 26 Registered: Nov-04 | 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. |
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Gold Member Username: GlasswolfNorthWest, Michigan USA Post Number: 7530 Registered: Dec-03 | 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." from audio amplifier fundamentals http://www.wickedcases.com/caraudio/amplifiers.html |
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Gold Member Username: GlasswolfNorthWest, Michigan USA Post Number: 7531 Registered: Dec-03 | those new MTX amps you mentioned may be using a 70 volt power supply, which is something a lot of car makers are looking to switch to from the older conventional 12VDC we use today. |
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Silver Member Username: Jwbulger79Florida Post Number: 467 Registered: Nov-04 | good to "see" you, glass. educational as always. how's the charger coming along? |
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Gold Member Username: GlasswolfNorthWest, Michigan USA Post Number: 7542 Registered: Dec-03 | doin' great. |
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Silver Member Username: Suleman36Post Number: 566 Registered: Feb-05 | 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 |
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Silver Member Username: Jwbulger79Florida Post Number: 470 Registered: Nov-04 | 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. |
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Silver Member Username: Suleman36Post Number: 573 Registered: Feb-05 | Yeah i read somthing similar to that J.W. thanks though. I honestly rather use the ZAPCO but it looks like a close call... anyone else know what to run for better efficiancy/draw less current? |
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Silver Member Username: Suleman36Post Number: 575 Registered: Feb-05 | ? |
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Silver Member Username: Jwbulger79Florida Post Number: 471 Registered: Nov-04 | 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. |
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Silver Member Username: Suleman36Post Number: 576 Registered: Feb-05 | Yeah for sure. Just trying to make up my mind on that. |
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Silver Member Username: Suleman36Post Number: 588 Registered: Feb-05 | Is $430 a good deal on a new ZAPCO referance 500M Mono amp. It does 500 x 1 @4ohms and 700 x 2 @2ohms?????? |
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Gold Member Username: GlasswolfNorthWest, Michigan USA Post Number: 7563 Registered: Dec-03 | 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. |
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Silver Member Username: Suleman36Post Number: 595 Registered: Feb-05 | thing is i have a offer on the table and its going down sooon so i tried to get as much info as i could. |