JimJ
5,000+ posts
Tangled Up in Blue
I hate to disagree, but I will //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif
JimJ
- Thread Starter
- #33
Enclosure it is now I've got to decide 32 or 35 hz
DBfan187
5,000+ posts
Supa's mom was here!
didn't mean it like that
csu87
10+ year member
CarAudio.com Veteran
if you want lows then dont do 35hz. if you want decent lows and ability to hit highs as well do 35hz or higher
tRiGgEr
5,000+ posts
CarAudio.com Veteran
It's ok you're technically correct //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif
Class A amps reproduce the input sine wave just like the output sine wave.
Class B amps reproduce 50% of the sine wave.
Class A/B only produce about 75% of the original sine wave.
And since class D are built and designed to be more efficient they only reproduce about 25% of the original sine wave.
Now my question to clarify all this, and I'm sure you may have the answer is...
Are all Class D amps limited to reproducing signals limited by there switching capabilities?
Does this mean a class D amp will not play a 10k hz signal? Or is it dependent on the amps switching capability?
tRiGgEr
5,000+ posts
CarAudio.com Veteran
From what I understand Class D's can only reproduce square waves due to the technology involved. And this is why they are used on Subwoofers. Trying to use a class D amp on a set of speakers would sound rather lifeless.
But they still reproduce the signal right? Just not fully?
But they still reproduce the signal right? Just not fully?
tRiGgEr
5,000+ posts
CarAudio.com Veteran
Where is Jmac, Squeak, JimJ...
yeah get ur booty in here and shed some light on it.
yeah get ur booty in here and shed some light on it.
SSS 18734
5,000+ posts
Dollar Menu Millionaire
My guess is that the Hifonics rated that frequency response at full power output and at advertised distortion ratings.
Many amps aren't capable of producing full power below a certain frequency. So it was either a) rate the amp at a lower power level or b) reduce the frequency response. They chose B.
So essentially, your hifonics amp will play whatever frequency you throw at it - however, it won't produce 100% of it's rated power below a certain point.
Many amps aren't capable of producing full power below a certain frequency. So it was either a) rate the amp at a lower power level or b) reduce the frequency response. They chose B.
So essentially, your hifonics amp will play whatever frequency you throw at it - however, it won't produce 100% of it's rated power below a certain point.
JimJ
5,000+ posts
Tangled Up in Blue
PWM amps like Class Ds don't fall into the linear categories like the other ones listed. Class C only amplifies 25% of the input signal //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif
I haven't done much hands-on with PWM topologies so I can't tell you for certain, but from what I've read, both the switching frequency and output LC filter plays a role in how linear and distortion-free the output is.
I have mixed feelings on switching amps for high-fidelity full range apps - I liked the Arc Minis (Class H) I heard, but at the same time, I've heard home amps based on Class T that sounded like garbage. So maybe stick with Zeff-designed ones, I don't know //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif
tRiGgEr
5,000+ posts
CarAudio.com Veteran
Power amplifier circuits (output stages) are classified as A, B, AB and C for analog designs, and class D and E for switching designs based upon the conduction angle or angle of flow, Θ, of the input signal through the (or each) output amplifying device, that is, the portion of the input signal cycle during which the amplifying device conducts. The image of the conduction angle is derived from amplifying a sinusoidal signal. (If the device is always on, Θ = 360°.) The angle of flow is closely related to the amplifier power efficiency. The various classes are introduced below, followed by more detailed discussion under individual headings later on.
Class A
100% of the input signal is used (conduction angle Θ = 360° or 2π; i.e., the active element remains conducting[5] (works in its "linear" range) all of the time. Where efficiency is not a consideration, most small signal linear amplifiers are designed as Class A. Class A amplifiers are typically more linear and less complex than other types, but are very inefficient. This type of amplifier is most commonly used in small-signal stages or for low-power applications (such as driving headphones).
Class B
50% of the input signal is used (Θ = 180° or π; i.e., the active element works in its linear range half of the time and is more or less turned off for the other half). In most Class B, there are two output devices (or sets of output devices), each of which conducts alternately (push–pull) for exactly 180° (or half cycle) of the input signal; selective RF amplifiers can also be implemented using a single active element.
These amplifiers are subject to crossover distortion if the transition from one active element to the other is not perfect, as when two complementary transistors (i.e., one PNP, one NPN) are connected as two emitter followers with their base and emitter terminals in common, requiring the base voltage to slew across the region where both devices are turned off.[6]
Class AB
Here the two active elements conduct more than half of the time as a means to reduce the cross-over distortions of Class B amplifiers. In the example of the complementary emitter followers a bias network allows for more or less quiescent current thus providing an operating point somewhere between Class A and Class B. Sometimes a figure is added (e.g., AB1 or AB2) with higher figures implying a higher quiescent current and therefore more of the properties of Class A.
Class D
Main article: Switching amplifier
These use switching to achieve a very high power efficiency (more than 90% in modern designs). By allowing each output device to be either fully on or off, losses are minimized. The analog output is created by pulse-width modulation; i.e., the active element is switched on for shorter or longer intervals instead of modifying its resistor. There are more complicated switching schemes like sigma-delta modulation, to improve some performance aspects like lower distortions or better efficiency.
Other classes
There are several other amplifier classes, although they are mainly variations of the previous classes. For example, Class G and Class H amplifiers are marked by variation of the supply rails (in discrete steps or in a continuous fashion, respectively) following the input signal. Wasted heat on the output devices can be reduced as excess voltage is kept to a minimum. The amplifier that is fed with these rails itself can be of any class. These kinds of amplifiers are more complex, and are mainly used for specialized applications, such as very high-power units. Also, Class E and Class F amplifiers are commonly described in literature for radio frequencies applications where efficiency of the traditional classes in are important, yet several aspects not covered elsewhere (eg: amplifiers often simply said to have a gain of x dB - so what power gain?)deviate substantially from their ideal values. These classes use harmonic tuning of their output networks to achieve higher efficiency and can be considered a subset of Class C due to their conduction angle characteristics.
http://en.wikipedia.org/wiki/Electronic_amplifier
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