TDA car-audio chip amp: purpose of output caps

[13hm13]

not the AD8397

There is nothing in the datasheet that would suggest that it can swing below its negative rail.

I don't believe anyone did say the AD8397 can swing below its negative rail. There are a other ways of driving headphones from an op-amp such as the AD8397 without using AC coupling capacitors but that wasn't the original topic of this thread.

It doesn't need to swing negative to work ... It Doesn't Need To Swing Negative to Work! ... IT effin' DOESN'T NEED to effin' SWING effin' NEGATIVE to effin' WORK!!!!
Duhhhhhhhhhh!!!
Dave went over this in his opamp video,EEVblog #600 - OpAmps Tutorial - What is an Operational Amplifier? (around 28:00):

[David_AVD]

So you're proposing to drive the speaker on the positive half of the waveform and let it "spring back" for the negative half?

[wraper]

not the AD8397

There is nothing in the datasheet that would suggest that it can swing below its negative rail.

I don't believe anyone did say the AD8397 can swing below its negative rail. There are a other ways of driving headphones from an op-amp such as the AD8397 without using AC coupling capacitors but that wasn't the original topic of this thread.

It doesn't need to swing negative to work ... It Doesn't Need To Swing Negative to Work! ... IT effin' DOESN'T NEED to effin' SWING effin' NEGATIVE to effin' WORK!!!!
Duhhhhhhhhhh!!!
Dave went over this in his opamp video,EEVblog #600 - OpAmps Tutorial - What is an Operational Amplifier? (around 28:00):

[BradC]

So you're proposing to drive the speaker on the positive half of the waveform and let it "spring back" for the negative half?

Damping? What Damping?

[dannyf]

IT effin' DOESN'T NEED to effin' SWING effin' NEGATIVE to effin' WORK!!!!

You don't have to shout.

To you point, how do you propose to get an ac current through the speaker cone if is is subject to a dc signal?

[Alex Eisenhut]

Sigh. "there's". Indeed there's no hope.

[Alex Eisenhut]

So you're proposing to drive the speaker on the positive half of the waveform and let it "spring back" for the negative half?

I believe that was the gist of his informational animated gif/rant.

It's hard to tell; he always seems to answer the question he heard rather than the question that was asked.

[BradC]

The Gene pool is green beyond Chlorine I'm afraid. Does this rag smell like Chloroform to you?

[mikerj]

not the AD8397

There is nothing in the datasheet that would suggest that it can swing below its negative rail.

I don't believe anyone did say the AD8397 can swing below its negative rail. There are a other ways of driving headphones from an op-amp such as the AD8397 without using AC coupling capacitors but that wasn't the original topic of this thread.

It doesn't need to swing negative to work ... It Doesn't Need To Swing Negative to Work! ... IT effin' DOESN'T NEED to effin' SWING effin' NEGATIVE to effin' WORK!!!!
Duhhhhhhhhhh!!!
Dave went over this in his opamp video,EEVblog #600 - OpAmps Tutorial - What is an Operational Amplifier? (around 28:00):

You are quite correct, the output of the amplifier itself does not need to swing negative, but the signal applied to the speaker absolutely must swing negative; the net DC component applied to the speaker needs to be kept to very small values, preferably zero.  It is the job of your "emergency"  caps to remove the DC bias from a conventional power amp run from a single supply rail.

I appreciate you are finding this entire topic very difficult to understand, but the capacitor effectively converts a 0 to Vcc swing to a -Vcc/2 to +Vcc/2 swing.

[Alex Eisenhut]

not the AD8397

There is nothing in the datasheet that would suggest that it can swing below its negative rail.

I don't believe anyone did say the AD8397 can swing below its negative rail. There are a other ways of driving headphones from an op-amp such as the AD8397 without using AC coupling capacitors but that wasn't the original topic of this thread.

It doesn't need to swing negative to work ... It Doesn't Need To Swing Negative to Work! ... IT effin' DOESN'T NEED to effin' SWING effin' NEGATIVE to effin' WORK!!!!
Duhhhhhhhhhh!!!
Dave went over this in his opamp video,EEVblog #600 - OpAmps Tutorial - What is an Operational Amplifier? (around 28:00):

You are quite correct, the output of the amplifier itself does not need to swing negative, but the signal applied to the speaker absolutely must swing negative; the net DC component applied to the speaker needs to be kept to very small values, preferably zero.  It is the job of your "emergency"  caps to remove the DC bias from a conventional power amp run from a single supply rail.

I appreciate you are finding this entire topic very difficult to understand, but the capacitor effectively converts a 0 to Vcc swing to a -Vcc/2 to +Vcc/2 swing.

Ya know, I wonder if he has speakers with a weird crossover network that has a cap in series with the woofer anyways, which is why removing the cap from the amp works?

I don't know enough about passive crossovers but I've always seen them with a LC lowpass filter with the cap in parallel at the woofer.

[Zero999]

not the AD8397

There is nothing in the datasheet that would suggest that it can swing below its negative rail.

I don't believe anyone did say the AD8397 can swing below its negative rail. There are a other ways of driving headphones from an op-amp such as the AD8397 without using AC coupling capacitors but that wasn't the original topic of this thread.

It doesn't need to swing negative to work ... It Doesn't Need To Swing Negative to Work! ... IT effin' DOESN'T NEED to effin' SWING effin' NEGATIVE to effin' WORK!!!!
Duhhhhhhhhhh!!!
Dave went over this in his opamp video,EEVblog #600 - OpAmps Tutorial - What is an Operational Amplifier? (around 28:00):

In order to drive a speaker properly, the positive terminal of the speaker needs to both swing above and below the negative terminal of the speaker. The negative terminal of the speaker may or may not be at the same voltage as the negative supply voltage.

Again, I repeat, this thread is about the TDA7273, which uses DC blocking capacitors and the positive terminal of the speaker does indeed swing below the power supply's negative rail.

[dannyf]

speakers with a weird crossover network that has a cap in series with the woofer anyways, which is why removing the cap from the amp works?

It would be odd for a woofer to have a serial capacitor (only). If the serial capacitor is in parallel with an inductor, then the same problem persists.

Serial capacitor (only) for a tweeter makes sense, however.

I don't know enough about passive crossovers but I've always seen them with a LC lowpass filter with the cap in parallel at the woofer.

The speaker would defeat the capacitor in parallel.

[Alex Eisenhut]

speakers with a weird crossover network that has a cap in series with the woofer anyways, which is why removing the cap from the amp works?

It would be odd for a woofer to have a serial capacitor (only). If the serial capacitor is in parallel with an inductor, then the same problem persists.

Serial capacitor (only) for a tweeter makes sense, however.

I don't know enough about passive crossovers but I've always seen them with a LC lowpass filter with the cap in parallel at the woofer.

The speaker would defeat the capacitor in parallel.

Eh wot? "LC lowpass filter with the cap in parallel at the woofer"





That's the way they've always looked to me.

[13hm13]

mikerj  urinated ...

You are quite correct,

 
TRYIN' TO PATRONIZE? ..... PFFFFTTTTTT!!!     

...
the output of the amplifier itself does not need to swing negative, but the signal applied to the speaker absolutely must swing negative; the net DC component applied to the speaker needs to be kept to very small values, preferably zero.  It is the job of your "emergency"  caps to remove the DC bias from a conventional power amp run from a single supply rail.

I appreciate you are finding this entire topic very difficult to understand, but the capacitor effectively converts a 0 to Vcc swing to a -Vcc/2 to +Vcc/2 swing.

pssst ...the caps are there for emergency DC protection (the amp/speaker will work, with single supply, w/o those caps) ....the caps are there for emergency DC protection (the amp/speaker will work, with single supply, w/o those caps) ... the caps are there for emergency DC protection (the amp/speaker will work, with single supply, w/o those caps).

Oh, and uh, one more thing...

[BradC]

pssst ...the caps are there for emergency DC protection (the amp/speaker will work, with single supply, w/o those caps) ....the caps are there for emergency DC protection (the amp/speaker will work, with single supply, w/o those caps)

You say it will, we know it won't. You made the assertion, now would be the appropriate time for YOU to prove us wrong. Put up or shut up.

[ludzinc]

mikerj  urinated ...

You are quite correct,

 
TRYIN' TO PATRONIZE? ..... PFFFFTTTTTT!!!     

...
the output of the amplifier itself does not need to swing negative, but the signal applied to the speaker absolutely must swing negative; the net DC component applied to the speaker needs to be kept to very small values, preferably zero.  It is the job of your "emergency"  caps to remove the DC bias from a conventional power amp run from a single supply rail.

I appreciate you are finding this entire topic very difficult to understand, but the capacitor effectively converts a 0 to Vcc swing to a -Vcc/2 to +Vcc/2 swing.

pssst ...the caps are there for emergency DC protection (the amp/speaker will work, with single supply, w/o those caps) ....the caps are there for emergency DC protection (the amp/speaker will work, with single supply, w/o those caps) ... the caps are there for emergency DC protection (the amp/speaker will work, with single supply, w/o those caps).

Oh, and uh, one more thing...

Shout it out as loud as you want.

You're still wrong.

[Alex Eisenhut]

mikerj  urinated ...

You are quite correct,

 
TRYIN' TO PATRONIZE? ..... PFFFFTTTTTT!!!     

...
the output of the amplifier itself does not need to swing negative, but the signal applied to the speaker absolutely must swing negative; the net DC component applied to the speaker needs to be kept to very small values, preferably zero.  It is the job of your "emergency"  caps to remove the DC bias from a conventional power amp run from a single supply rail.

I appreciate you are finding this entire topic very difficult to understand, but the capacitor effectively converts a 0 to Vcc swing to a -Vcc/2 to +Vcc/2 swing.

pssst ...the caps are there for emergency DC protection (the amp/speaker will work, with single supply, w/o those caps) ....the caps are there for emergency DC protection (the amp/speaker will work, with single supply, w/o those caps) ... the caps are there for emergency DC protection (the amp/speaker will work, with single supply, w/o those caps).

Oh, and uh, one more thing...

Simply make the breadboard and measure the output with no load. Or send me a chip.

Or describe a situation that would qualify as a DC emergency.

[Richard Crowley]

Simply make the breadboard and measure the output with no load. Or send me a chip.

Or describe a situation that would qualify as a DC emergency.

You are wasting your time. 13hm13 clearly doesn't even understand the question, so he would be unable to respond coherently.

People who don't know what they don't know think that the rest of us are just ganging up on them to be mean.
They don't have any useful understanding of the underlying concepts they think they are discussing.

[Alex Eisenhut]

Simply make the breadboard and measure the output with no load. Or send me a chip.

Or describe a situation that would qualify as a DC emergency.

You are wasting your time. 13hm13 clearly doesn't even understand the question, so he would be unable to respond coherently.

People who don't know what they don't know think that the rest of us are just ganging up on them to be mean.
They don't have any useful understanding of the underlying concepts they think they are discussing.

I think you're wrong. Once someone uses 36 point font, you know you're wrong and they're right. Now it's just a question of getting some measurements...

[David_AVD]

Dunning Kruger effect 

[chickenHeadKnob]

Dunning Kruger effect 

You might be right David, but my internet spidey senses tell me 13ohm is just an old fashioned troll and a rather expert one at that. He knows just what buttons to push. Simon should have locked this thing down.

[IanJ]

Clear yet?

Ian.

[wraper]

I'm really amazed how you guys still can answer him seriously. I wouldn't even try to do that after a few of his posts. It's just Sisyphean labor regardless if he is a troll or just non smart. Even if he will understand finally, he does not deserve your effort because of his altitude.

[wraper]

I even would say that he deserves a lesson in a hard way - burned speakers and amplifier.

[BradC]

Or describe a situation that would qualify as a DC emergency.

Fire at the Whitehouse?