At least after post#2 you should have downloaded and read it......Thanks. Would not have thought of that so very interesting and useful.
Still not totally clear though. Is that the data sheet for the LM386?
So at 9V it has a max output of 0.5W?
What would be the effect of using a, say, 5W 8ohm speaker?
Unless I am mistaken a 5W speaker rating refers to voice coil power handlingHi Dana,
Thanks. Would not have thought of that so very interesting and useful.
Still not totally clear though. Is that the data sheet for the LM386?
So at 9V it has a max output of 0.5W?
What would be the effect of using a, say, 5W 8ohm speaker?
Regards,
Alistair
1)Would not the middle amp have its NI input grounded, after dropping out the bottomThe Stereo Bridge circuit has a couple of serious problems:
1) If there is the same signal (mono) input to each channel then the center LM386 has the same signal on both of its inputs which cancel and produce zero output.
Then there is no bridging. The stereo speakers produce an out-of-phase sound.
2) The LM386 is overloaded when bridged. Each of the three amplifiers has a 4 ohm current. The LM386 works poorly with a 4 ohm load.
If there is a signal on only one channel then the middle LM386 and the playing channel are trying to produce double the current in one 8 ohm speaker which reduces the output level due to overloading.
Then there is a small bridging power boost and lots more heating.
With a 9V supply, the output power of an LM386 amplifier with a 9V supply and an 8 ohm speaker is 0.45W with low distortion. The amplifier heats with 0.5W.
With a 9V supply, the output power of a bridged LM386 amplifier with a 9V supply and an 8 ohm speaker is 0.6W with low distortion. Each amplifier heats with 0.8W.
0.6W is far from the 2W that is claimed.
And, most importantly, you gain very little (if any) and lose a lot (quality sound).I wouldn't recommend that schematic, using a common bridge between two channels will cause horrible crosstalk problems.
Any loudspeaker with a power rating higher than the amplifier can produce is safe to use.
In general, the higher the power rating of a loudspeaker, the less sensitive it is so try to use one rated a little higher than the amp for best volume. Using one with a much higher power rating will do no harm but will sound quieter.
Hi Brian,I wouldn't recommend that schematic, using a common bridge between two channels will cause horrible crosstalk problems.
However, that wasn't the original question, the answer to which is:
Any loudspeaker with a power rating higher than the amplifier can produce is safe to use.
In general, the higher the power rating of a loudspeaker, the less sensitive it is so try to use one rated a little higher than the amp for best volume. Using one with a much higher power rating will do no harm but will sound quieter.
Brian.
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