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Thread: Question about class D amps |
    
Silver Member Username: Davids2004
Houston,
TX
USA
Post Number: 495
Registered: Jun-04
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| Posted on Wednesday, August 11, 2004 - 08:22 pm: |
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Do they put less strain on your electrical system then a class AB amp.
Thanks. |
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Bronze Member Username: Invain
Post Number: 29
Registered: Aug-04
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| Posted on Wednesday, August 11, 2004 - 09:41 pm: |
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I think so, class D amps don't require as much power as AB |
Gold Member Username: Jonathan_f
GA
USA
Post Number: 1094
Registered: May-04
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| Posted on Thursday, August 12, 2004 - 08:19 am: |
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No, they don't strain it as much for the equivalent power. Class D amps are about 80% efficient (80% ends up as power, 20% goes to heat) and Class AB amps are about 50-60% efficient depending on design. |
New member Username: Blindc1rca
Post Number: 1
Registered: Aug-04
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| Posted on Thursday, August 12, 2004 - 09:55 am: |
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Yea, I have a directed 750d, f-ing amazing amp by the way. Class D amps the best way to go for subwoofers because subs require so much power.
Heres the actual definition of the classes:
Amplification Classes.
All sound is a sinosoidial waveform. It has alternating peaks and valleys. The center point of each wave is the zero, or switching point that separates the positive (top) from the negative (bottom) portion of each wave. When a tube or transistor amplifier operates in Class A, the output tubes or transistors amplify the entire waveform without splitting it into positive and negative halves. In Class AB, used in the overwhelming majority of amplifier designs, the signal is split into two halves, positive and negative, and each half is sent to a tube or transistor circuit for amplification. Both sides work in tandem, and the two halves are recombined at the output section to reconstruct the whole signal. This technique increases the amount of power that can be applied, but increases distortion. Class A amps usually provide lower, often imperceptable distortion, but at the expense of reduced power output.Class D or High Current operation is essentially rapid switching, hence the term switching power amplifier. Here the output devices are rapidly switched on and off at least twice for each cycle. Theoretically, since the output devices are either completely on or completely off they do not dissipate any power. If a device is on there is a large amount of current flowing through it, but all the voltage is across the load, so the power dissipated by the device is zero; and when the device is off, the voltage is large, but the current is zero. Consequently, class D operation (often, but not necessarrily digital) is theoretically 100% efficient, but this requires zero on-impedance switches with infinitely fast switching times -- a product yet to be made; meanwhile designs do exist with efficiencies approaching 90%. This is a design that is increasimgly popular for use in bass systems, where maximum power is necessary, and slightly elevated levels of distortion are easily tolerated.
Dude, go to http://www.electronixwarehouse.com/education/glossary/
It has everything you ever need to know before buying aftermarket car audio, its friggin unbelievable. |
New member Username: Blindc1rca
Post Number: 2
Registered: Aug-04
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| Posted on Thursday, August 12, 2004 - 09:58 am: |
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So basically you can have an A/B amp sucking 1300 watts out of your battery just to give your subs 600 watts continuous power or you can have a class D amp sucking 750w out of your battery to provide your subs with 600w of power (assuming you have 2 subs that have 4 ohm DVC's and have them wired to 1 ohm). |
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