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-   -   lm386 heatsinks (http://www.diyaudio.com/forums/chip-amps/225103-lm386-heatsinks.html)

calgarc 6th December 2012 07:34 AM

lm386 heatsinks
 
a heatsink on an lm386 or 2 lm386's so on... is it necessary at higher voltages or not??

Mooly 6th December 2012 07:56 AM

Not needed. Best practice here is to use the PCB with largish copper pads to carry heat away. Remember this is a chip intended for battery powered audio such as portable radios and stuff.

calgarc 6th December 2012 08:01 AM

i know... i just have a whole bunch of GPU heatsinks laying around as well as a bunch of 386n-4 chips... tempted to bridge a few with heatsinks to see how they perform. just an expiriment

johnr66 6th December 2012 03:19 PM

The LM386 is not a good choice for bridging. Current drive is so limited with it that power folds up quite a bit under load.

Here's a list of IC output power using a regulated 9v supply. The power is continuous sine wave before clipping into non inductive loads.
http://www.jracrylic.com/pix/chipamp.jpg
As you can see, some ICs can practically double the output of the LM386 with 4 ohm loads.

calgarc 6th December 2012 10:17 PM

Quote:

Originally Posted by johnr66 (Post 3273226)
The LM386 is not a good choice for bridging. Current drive is so limited with it that power folds up quite a bit under load.

Here's a list of IC output power using a regulated 9v supply. The power is continuous sine wave before clipping into non inductive loads.
http://www.jracrylic.com/pix/chipamp.jpg
As you can see, some ICs can practically double the output of the LM386 with 4 ohm loads.

thanks :D in the end its just an expiriment lol but that table helps

JMFahey 7th December 2012 12:05 AM

Let me add the Chipamp I use commercially: TBA820M .
I searched a lot and it's the best one available when the supply is 9V.
And it keeps working down to 3V, so *very* dead batteries still provide *some* sound to save a boring night, until shops open in the morning.
From its datasheet:
Quote:

Output power: Po = 2W at 12V/8r , 1.6W at 9V/4r
and 1.2W at 9V/8r.
www.kolumbus.fi/mikko.esala/d/tba820.pdf
Can be bridged for incredible 3.2W RMS into 8r out of a 9V supply.

sofaspud 7th December 2012 12:17 AM

Interesting because I could use a couple small amps in this power range for some portable speakers I own. How does this TBA820M sound? You didn't really state your reason for declaring it the best, other than output power.

AndrewT 7th December 2012 11:13 AM

I downloaded the tba820 datasheet, thinking it would be useful.
Now that I have read said datasheet, I have not saved it. The performance is dreadful.
minimum distortion ~1/3 of a percent.
0.5% distortion at 1/2W
noise -70dB ref 1.2W

I wonder if it is a ClassB output stage to save battery power?

sofaspud 7th December 2012 11:51 AM

That's helpful:) I asked because I wasn't familiar with this chip. It doesn't seem to be very much different than the TDA2822 that I currently have. I've been looking for something a little cleaner and quieter.

johnr66 7th December 2012 03:26 PM

Quote:

Originally Posted by AndrewT (Post 3274501)
I downloaded the tba820 datasheet, thinking it would be useful.
Now that I have read said datasheet, I have not saved it. The performance is dreadful.
minimum distortion ~1/3 of a percent.
0.5% distortion at 1/2W
noise -70dB ref 1.2W

I wonder if it is a ClassB output stage to save battery power?

This is an ancient chip. It needs a lot of external components to make it work including external frequency compensation (not common on modern low power audio amp ICs). Distortion isn't really that bad. I doubt it could swing any better than 2.25 Vrms into an 8 ohm load @ 9v Vs. Some tube nuts would say a 35C5 SE tube amp, with a few percent distortion at best, would sound better.


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