What are the differences between the 3875, 3886, and 4780?

AJ Bertelson · 24th January 2006, 01:16 AM

Is it just power output?

I haven't been around this forum for awhile I picked up the briangt kit on the very first group buy and I finally got it working just last week, two 50k pots fixed my buzzing problems. Anyways I noticed there is a two new additions to the chipamp group but I know nothing about them. I am in the process of building up a 7 channel gainclone 3875 but I wonder if I should have waited for the other two.

lineup · 24th January 2006, 02:46 AM

I beginning there was LM1875
and .....

National Semiconductor calls this series of amps Overture.
Here, at National website, you can compare all those audio amplifier chips:

National Audio Amplifier IC - Overview and data page

lineup · 24th January 2006, 04:02 AM

Quote:

Originally posted by AJ Bertelson

What are the differences between the 3875, 3886, and 4780?
Is it just power output?

no it is not just power

LM3875 is a very good and stable IC for 4/8 Ohm.
Good for first project, to get some experience.
I prefer the standard setup schematic in datasheet.
You've got to love this IC!

LM3886 can put out more current than LM3875, almost twice as much,
before Current Limit is activated (SPiKe protection).
This makes LM3886 better suited for 4 Ohm at higher powers.
LM3886 is also faster than LM3875.
Higher slewrate. (If you are unlucky you can get oscillation.)

LM4780 is judging from data two LM3886 in same chip.
This gives a bit reduced high power performance, compared to two LM3886.
Mainly because 2 chips can cool better, than one chip. (Larger cooling surface)

AJ Bertelson · 24th January 2006, 05:28 AM

Well if you bridge up two 3875's would they be equal to one 3886?

Nordic · 24th January 2006, 06:43 AM

I would suggest you just try a plain LM3875... with the right speakers they get pretty loud.

I see you have tried the Brian GTs, I have the fortune of haveing quite old speakers (in the good old days they made some nice and efficient speakers that the average Joe could afford), Now even if the single chip is not quite as loud as you seem to like.. imagine a handfull of them driving speakers.. I'm sure it will get quite intense.

One of the benefits I see to 3875 is lower power demands = cheaper PSUs.

Output from 3875 is about 75% of 3886

dfdye · 24th January 2006, 07:47 PM

While this thread is active, I have a set of speakers that average ~6 ohms but dip to just under 4 in a couple of spots. When gaguing which chips to use, should I use assume a 6 or 4 ohm load for the chips?

My gut says 6, but I figured you guys would be the folks to ask.

24th January 2006, 01:16 AM	#1
AJ Bertelson diyAudio Member Join Date: Jan 2003 Location: Maple Grove, MN	What are the differences between the 3875, 3886, and 4780? Is it just power output? I haven't been around this forum for awhile I picked up the briangt kit on the very first group buy and I finally got it working just last week, two 50k pots fixed my buzzing problems. Anyways I noticed there is a two new additions to the chipamp group but I know nothing about them. I am in the process of building up a 7 channel gainclone 3875 but I wonder if I should have waited for the other two.

24th January 2006, 02:46 AM	#2
lineup diyAudio Member Join Date: Dec 2005 Location: the north	I beginning there was LM1875 and ..... National Semiconductor calls this series of amps Overture. Here, at National website, you can compare all those audio amplifier chips: National Audio Amplifier IC - Overview and data page __________________ lineup

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24th January 2006, 05:28 AM	#4
AJ Bertelson diyAudio Member Join Date: Jan 2003 Location: Maple Grove, MN	Well if you bridge up two 3875's would they be equal to one 3886?

24th January 2006, 06:43 AM	#5
Nordic diyAudio Member Join Date: Sep 2005	I would suggest you just try a plain LM3875... with the right speakers they get pretty loud. I see you have tried the Brian GTs, I have the fortune of haveing quite old speakers (in the good old days they made some nice and efficient speakers that the average Joe could afford), Now even if the single chip is not quite as loud as you seem to like.. imagine a handfull of them driving speakers.. I'm sure it will get quite intense. One of the benefits I see to 3875 is lower power demands = cheaper PSUs. Output from 3875 is about 75% of 3886

24th January 2006, 07:47 PM	#6
dfdye diyAudio Member Join Date: Dec 2005 Location: USA	While this thread is active, I have a set of speakers that average ~6 ohms but dip to just under 4 in a couple of spots. When gaguing which chips to use, should I use assume a 6 or 4 ohm load for the chips? My gut says 6, but I figured you guys would be the folks to ask.

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