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Old 6th December 2012, 07:34 AM   #1
calgarc is offline calgarc  Canada
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Lightbulb lm386 heatsinks

a heatsink on an lm386 or 2 lm386's so on... is it necessary at higher voltages or not??
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Old 6th December 2012, 07:56 AM   #2
Mooly is offline Mooly  United Kingdom
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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.
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Old 6th December 2012, 08:01 AM   #3
calgarc is offline calgarc  Canada
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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
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Old 6th December 2012, 03:19 PM   #4
johnr66 is offline johnr66  United States
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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.
Click the image to open in full size.
As you can see, some ICs can practically double the output of the LM386 with 4 ohm loads.
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Old 6th December 2012, 10:17 PM   #5
calgarc is offline calgarc  Canada
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Quote:
Originally Posted by johnr66 View Post
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.
Click the image to open in full size.
As you can see, some ICs can practically double the output of the LM386 with 4 ohm loads.
thanks in the end its just an expiriment lol but that table helps
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Old 7th December 2012, 12:05 AM   #6
JMFahey is offline JMFahey  Argentina
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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.
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Old 7th December 2012, 12:17 AM   #7
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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.
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Old 7th December 2012, 11:13 AM   #8
AndrewT is offline AndrewT  Scotland
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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?
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Old 7th December 2012, 11:51 AM   #9
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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.
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Old 7th December 2012, 03:26 PM   #10
johnr66 is offline johnr66  United States
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Quote:
Originally Posted by AndrewT View Post
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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