A lot of consumers read Car Stereo Reviews and AS&S reviews of amplifiers where they take apart the amplifier and discuss the guts, power supply, mosfet type (or hexfet with adcom ) capacitor size, voltage rails blah blah blah.
The average and even the above average consumer reads this and goes.. Hmmmm, skip to the graphs.
Perhaps a discussion of the different types of amplifiers (I.E. mono vs. multiple channel, bridgeable, high voltage, high current, high power, different classes (A and D (where's the F? Oh I forgot, thats Kraco's class )
This is just a possible idea for an advanced discussion topic.. Any takers??
(STARING DIRECTLY AT TECH MAN---- )
ShadowStar
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Posts: 2578 | From: Somewhere In the Northeast | Registered: May 1999
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Heck, I have a hard time keeping up with an amp review - or awake for that matter. How much? (power) How low? (impedance) How long? (before it melts) The rest is gravy......
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Lord Dukk The Big Show The Dukk says: Know your bass: PORT your damn box!!
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Dukk cant keep up with the amp reviews only because theres no where for him to swim! Well, with the exception of the old PPI watercooled ones....
------------------ http://members.tripod.com/Audiophyle Ba Chomp, Ba Chewy Chomp, Ba Chewy Chewy CHOMP!! Someday, we'll all look back on this, laugh nervously, and change the subject!!
Posts: 3120 | From: nowhere | Registered: May 1999
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I guess since tech hasn't answered and you want somebody to do it I'll give it a shot.
Mono amplifiers- one channel amplifier has separate power supply. There are dual mono amps that are two separate mono amps in one chassis.
Multi channel- An amp that has more than one channel usually has one power supply for all channels.
Bridgeable- the ability of a amplifier to combine two channels together to have one higher power channel.
High current- the output section of the amp is designed to pass large amounts of current allowing the amp to make full power at low impedance.
High voltage- the output section of the amp is designed to have a high output voltage making full power at higher impedances.
As for different classes: the AC signal coming out of an amp goes both above and below ground, in a class A design one output device will amplify the entire waveform. This design is inefficient due to the device always being in the middle of its operating range. There aren't many truly Class A car amps due to the ineffeciency.
In class B one device amplifies the negative portion and one amplifies the positive portion. This causes crossover distortion because there has to be a certian input to a device to turn it on so around zero neither device is on. Class AB is basically a class B design with some changes to make sure at least one output device is on at all times. This design is more efficient than class A but the design has to be good to avoid crossover distortion.
Class D is different the audio signal is changed into a pulse width modulated signal which is either on or off, this signal is sent to the output devices which turn on and off. If this signal is filtered you get basically an audio signal (with limitations). Class D is much more efficient around 85-90%. Basically with the differenty classes you trade distortion for more efficiency.
There is a class T amp similar to class D but with supposedly much better audio performance. There is also a design that varies the power supply voltage depending on signal.(I think Blade uses something like this)
As far as differences in output devices and designs all can be done with great result if designed correctly
Hopefully I explained this resonably well and didn't make too many mistakes.
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Ah somebody who has heard of Blade ,I have two small ones the SE52 and SE152 and yes they use a form of Class T but with their own twist. SE52 50 w x2 1.4"x 6" x9" SE152 50 w x2& 100 x1 1.4" x6" x12" Like it says below they aren't in my truck yet but maybe within the next month. I think Blade is becoming "Indigo" now?!? ------------------ newride No tunes yet but soon!!!
[This message has been edited by newride (edited 06-03-99).]
[This message has been edited by newride (edited 06-03-99).]
Posts: 43 | From: Abbotsford BC Canada | Registered: May 1999
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In class A you still have a pair of devices to handle the waveform. They are either all the way on at all times are mostly on when not used and full on when the waveform demands it. Yeah, A/B has a small amount of bias applied to both output outputs at idle and some hold bias all the way threw the waveform.
------------------ The Mack AKA Big Poppa Mack Daddy-- You better roll with the big mack, the man with the game Mack Daddy-- Gotta big snake, all you gotta do is make it dance, you know what I'm sayin'
[This message has been edited by The Mack (edited 06-03-99).]
Posts: 237 | From: East Texas | Registered: May 1999
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The blade amps.. Thats the one with BASH circuitry, right? Its a, get this, either a class A or Class A/B and Class D hybrid, that uses the Class D section for cooling and high power applications.. Looks very cool.. Do you know how it works?
ShadowStar
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Posts: 2578 | From: Somewhere In the Northeast | Registered: May 1999
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Blade amps using BASH technology have a normal class AB output. The difference is in the power supply. The power supply voltage varies depending on the need of the output section. This allows the amplifier to be more efficient for real world conditions where power output isn't at a maximum but I don't see that it would affect efficiency at max power.
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Ah, like Hifoniks Vari-power. Makes a huge efficiency difference at low and medium volumes. At high volumes though they weren't much different than other amps.
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I did some investigating on BASH technology and I find out I'm wrong about how it works. You can check out the white papers at http://bladeaudio.com/technology/bashwhite.htm I originally thought the power supply produced a DC power like most amps but varied the voltage depending on the power needs. I come to find out the power supply produces a voltage that is a couple volts above the amplifiers output voltage at all times. So if the amplifier is playing a sine wave the power supply voltage will look like a sine wave but two volts or so higher than the output. This keeps the voltage drop across the transistors small so the power dissipated in the output transistors will be lower. This is where the gain in efficiency comes from. I don't know how well I explained this but if you are interested the website above gives a good explanation
Is the whole purpose of saying "high voltage" simply marketing?
Because P= V*R and I=V/R, then when voltage goes up and the resistance stays the same (a given speaker load) does that not also mean that the current must increase, thereby increasing the power? Notice that in order to increase the voltage by X, the current increase is always equal to X/R.. So how can you have a high voltage amplifier that is not also high current?
On the other side of the token, for a given resistance and current increase, voltage must decrease.. Therefore, with an amplifier operating at a given (and low) impedance, the current output will increase, and the voltage output will decrease...
Therefore, aren't high voltage or high current amps simply high power amps minus the B.S. ?
ShadowStar
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Posts: 2578 | From: Somewhere In the Northeast | Registered: May 1999
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Yeah there both just high powered amps with different designed optimum loads. Like the old Lanzar 50c and what was the other version? the 2500?. The 'high current' version had supply rails in the + & - 25 volt range. In order to get the power up to 800 to 1000 watts you had to decrease impedance, R, to increase P. This is of course as a result of P=I*E. E is +-25V and R is reduced so I amps goes way up, thus high current. The high volt version gets the same power by just raising V real high to get the increase in P. Since you leave R at a more normal 2 or 4 ohms. And I doesn't get outrageously high like the high current design.
It's like gear ratio's. Same horsepower (same I and E going into amps) One amps has 2.56 gears for long high speed straights at great speed. High volt One amp has 4.56 gears for a quick accelaration. High current. And it's mostly that toroid transformer
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