LM3875 and class A?

moreismore · 11th January 2005, 07:00 PM

Has anyone tried this with the LM3875?
Is Class A always a better sound, better fidelity?

sivan_and · 12th January 2005, 02:52 AM

LM3875 and class A ? Kidding ?

moreismore · 12th January 2005, 04:05 AM

I was'nt, it seems like you know, but don't say. I thought Class A was the best. Tell me more.

theChris · 12th January 2005, 05:03 AM

there have been threads on this. see the thread about the "first watt gainclone".

ashok · 12th January 2005, 05:10 AM

An amp works in class A if the bias current through the output device is so high that it never drops to zero with an ac signal.

The LM chips are internally biased in class AB mode and you have no access to it. However if the load is very low ( high impedance ) , possibly something over 1 K ohm , it might run class A. I am not quite sure if that would be true either because the biasing level is very low and probably not in a very linear region like normal class A.

In any case to interface a speaker to the chip and load it ( the chip) differently you will need external power transistors and they can be biased into class A .
Cheers.

11th January 2005, 07:00 PM	#1
moreismore diyAudio Member Join Date: Jun 2004 Location: Toronto	LM3875 and class A? Has anyone tried this with the LM3875? Is Class A always a better sound, better fidelity?

12th January 2005, 02:52 AM	#2
sivan_and diyAudio Member Join Date: Dec 2004 Location: Dxb / India	LM3875 and class A ? Kidding ? __________________ SivanandBalan

12th January 2005, 05:03 AM	#4
theChris diyAudio Member Join Date: Dec 2001 Location: SIUE, Illinois, USA	there have been threads on this. see the thread about the "first watt gainclone". __________________ if only it could be used for good, not evil...

12th January 2005, 05:10 AM	#5
ashok diyAudio Member Join Date: Jun 2002 Location: 3RS	An amp works in class A if the bias current through the output device is so high that it never drops to zero with an ac signal. The LM chips are internally biased in class AB mode and you have no access to it. However if the load is very low ( high impedance ) , possibly something over 1 K ohm , it might run class A. I am not quite sure if that would be true either because the biasing level is very low and probably not in a very linear region like normal class A. In any case to interface a speaker to the chip and load it ( the chip) differently you will need external power transistors and they can be biased into class A . Cheers. __________________ AM

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12th January 2005, 04:05 AM	#3
moreismore diyAudio Member Join Date: Jun 2004 Location: Toronto	I was'nt, it seems like you know, but don't say. I thought Class A was the best. Tell me more.

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