Are Class B amps really that bad?
I’m looking for a 4-channel amp to drive 4 speakers. I found this (http://www.crutchfield.com/p_136J23204/JL-Audio-J2-320-4.html?tp=115). Its a class b amp. Ive read online that class b amps are notorious for distortion. Is the distortion really that bad? Should I be concerned? for should i spend the extra money and go with a class AB amp?
it a jl so its a good amp their known for sound quality but if your a sq freak them you might want the AB but it shouldnt be that bad
it a jl so its a good amp their known for sound quality but if your a sq freak them you might want the AB but it shouldnt be that bad
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Here’s an explanation of the different classes of amps.
http://www.bcae1.com/ampclass.htm
IMO go ahead and spend the extra money and get the class a/b amp
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Do the AB man its worth it. You get what you pay for.
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You brought up an interesting fact I have never noticed so I contacted JL’s VP of marketing. As always I got a quick and thorough response:
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Class B designs do, in fact, have an inherent minor distortion issue referred to as zero-cross distortion, or simply "crossover distortion". The Class B runs no bias current, so when the signal crosses zero there is a slight disruption that creates the distortion. Class A/B’s run a small amount of bias current at all times to prevent this. There is an efficiency penalty for running the bias current, so Class B’s are a bit more efficient than Class A/B’s. Here is a good explanation: http://www.aikenamps.com/CrossoverDistor…
Class B’s are less expensive to build and dial in because you don’t need a mechanism for biasing the rails or the potentiometer to tweak bias after assembly. This is why the vast majority of inexpensive amps on the market are actually Class B’s, even though they are rarely identified as such by their manufacturers. We’re just being honest.
If you open a non Class D amp, and you don’t see bias-trim potentiometers in each and every channel output section, then the amp is actually a Class B, regardless of any claim to the contrary by its manufacturer.
How big a deal is zero-cross distortion? Not a really huge deal. It depends on whether you just want good, clean sound or really spectacular sound. If you’re looking for the latter, then you’re probably not a J2 customer, but rather a G-Series or Slash (both are true Class A/B) or an XD or HD customer (ultra-high speed Class D).
Hope that answers your questions. Thanks for your interest in our products.
Manville Smith
VP-Marketing
JL Audio, Inc.
/quote
I wish I had a bigger audio budget — I’d buy their gear simply for responses like that from a VP
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