Need advice , please ? SUB Categories ?

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Hello Dear All,

As new to DIY each day I'm learning more and more that there is lot of things I don't know.
Someone please give links or direct ansver to :

1. Where in Europe (Baltics) I can find companies that sell DIY pars/kits over internet?
2. what does sub categories stand for ? like subamplifier "category A/B" or "D" or even noticed "H"?

Apreciate any anver, thanks.
Keshas

P.S. And yes, forgot to say - excelent site and forums!!!!
 
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Joined 2001
Keshas said:
2. what does sub categories stand for ? like subamplifier "category A/B" or "D" or even noticed "H"?

You are probably better off asking this question in the "Solid State" forum. I will give you a just a couple of types now, though.

Class A amp has one single output transistor. Even with no input signal, it is run at half voltage. Hence, heat is generated. As a result, most amps are not Class A. However, very high fidelity amps often use the Class A system because it does not switch back and forth between transistors for every waveform, like other common amp types do. You won't have to worry about your common subwoofer amplifier using the Class A configuration-this is strictly for super-audiophiles. Tube amps very often use the Class A configuration as well.

Class AB-probably the most common amp type. Compared to Class A, much less heat is generated. Output is turned on only slightly if no audio signal is present. However, every waveform it plays switches back and forth between two transistors. Some audiophiles think this generates distortion.

I would ask on the Solid State forum for Class G , Class H, or other class amps.
 
Kelticwizard is right on the Class A and AB. Class D is pulse width modulation - not very pretty and tends to give much higher distortion than class A or AB, but is much more efficient.

The theoretical maximum efficiency for a class A is 50% (if memory serves correct) and in practice is less than this, hence fairly impractical for LF amps, although it can be a neat solution for tweeter amps. The theoretical maximum efficiency for a class AB is 75% (please correct me if I've got this wrong - it wouldn't be the first time) and real-world amps are normally a bit lower than this although still a lot more practical than class A. Most high power pro-audio amps are class AB, as are many hifi amps - they can offer low distortion (a 3886 is about 0.05%THD I think) and you don't have huge heatsinking problems to deal with as you would with class A.

For your sub amp I'd go with a class AB version over a class D although to be honest the power supply is as important as the amp type. You generally need big smoothing capacitors (with a linear supply anyway) to make sure that there's enough current for the amp to draw on for LF transients which require a lot of energy.

Hope that helps.
 
Class H if I am not mistaken, is where the amplifier has a two stage power supply, one at a higher voltage than the other. The amplifier is switched between these two supplies dependent on how much power is being demanded at the time.

There is an amplifier called a BASH that tracks the power supply as well.
 
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