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 Chip Amps Amplifiers based on integrated circuits

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 29th June 2012, 11:09 AM #31 MarianB   diyAudio Member     Join Date: Jul 2011 Location: Romania I see you still have much to learn. it's like this: The amplifier has to drive the signal on both phases, possitive and negative ( think of it as one center line wich is the refference and the signal goes above and beyound that line ), now on a simetricall supply it is easy, the amplifier has both positive and negative voltage to help it drive the signal, but when using a single supply the amplifier first has to split the voltage so that it can have a refference point at the middle from wich it can drive the signal, on both supply config the amplifier has supply rails that it cannot exeed, so on a 12V single supply the amplifier split's it in half, and the SE config has at the output before the dc decoupling capacitor about half the Vin ( 6V for this ), those are the rails for the signal, 6V; now the BJT output devices in the IC need for them selves about .6-.7V to turn on so you are left with 5,4V maximum signal rail possible, and knowing that Pout=V^2/R you do the math.
lazzer408
diyAudio Member

Join Date: Sep 2010
Location: Chicago
Quote:
 Originally Posted by MarianB I see you still have much to learn. it's like this: The amplifier has to drive the signal on both phases, possitive and negative ( think of it as one center line wich is the refference and the signal goes above and beyound that line ), now on a simetricall supply it is easy, the amplifier has both positive and negative voltage to help it drive the signal, but when using a single supply the amplifier first has to split the voltage so that it can have a refference point at the middle from wich it can drive the signal, on both supply config the amplifier has supply rails that it cannot exeed, so on a 12V single supply the amplifier split's it in half, and the SE config has at the output before the dc decoupling capacitor about half the Vin ( 6V for this ), those are the rails for the signal, 6V; now the BJT output devices in the IC need for them selves about .6-.7V to turn on so you are left with 5,4V maximum signal rail possible, and knowing that Pout=V^2/R you do the math.
For lack of a better term I'll call it 6v of "bias". If it swings up to 11 and down to 1 (to choose even numbers) then it has 10v p-p of swing. Correct? Everything your telling me I understand. What I don't understand is how 10v can't produce more then 10w. Where are you coming up with it only being able to swing from 1/2vcc and down? Why not up?

 29th June 2012, 11:27 AM #33 MarianB   diyAudio Member     Join Date: Jul 2011 Location: Romania You still don't get it..( damn..am i so lousy at explayning stuff?...) The term is rail voltage, and it cannot swing upt to 10V and down 1V, it has to swing equally up and down, so it has to split the voltage in half, this example is at 6V, but it will not have a total of 12V peak to peak at the output, it cannot, because the refference point is already set in the middle of that so at the output without the dc cap it can only have +6v or -6V. Now you understand?
lazzer408
diyAudio Member

Join Date: Sep 2010
Location: Chicago
Yes that's how I understood it in the first place. You said "you are left with 5,4V maximum signal rail possible" Did you mean +/-5.4v? Which is 10.8v rail to rail swing. I used 11 and 1 as my example to keep numbers even. With a 6v center, swinging from 1v to 11v is +/-5v.

I drew this to show my understanding of the output.

Attached Images
 sine_wave (Small).png (39.2 KB, 57 views)

MarianB
diyAudio Member

Join Date: Jul 2011
Location: Romania
It's like this:
The signall allways starts from the refference point wich in this case is the middle 6V, and it only goes or above or beyound that point, but IT CANNOT GO BOTH WAYS AT THE SAME TIME, it can only go UP or DOWN at any time so the signall CANNOT BE more than 6V possitive or negative ( that is above or beyound that refference point ) minus about .6 needed by the bjt's.

If this doesn't helps you either than i suggest a boock for you to read urgently, it is called: The Art Of Electronics, read it cover to cover and you will surely undertand, cus if this does not help you than i give up, and call you a lost cause.
Attached Images
 sine_wave (Small).png (31.1 KB, 56 views)

Last edited by MarianB; 29th June 2012 at 07:20 PM.

 29th June 2012, 08:04 PM #36 lazzer408   diyAudio Member     Join Date: Sep 2010 Location: Chicago That's the same image I just drew. So yes, I do understand how it works and always have. Tell me how (almost) 12v of swing into 4ohm can only produce 10w.
 29th June 2012, 08:20 PM #37 MarianB   diyAudio Member     Join Date: Jul 2011 Location: Romania JESUS!!!!! Excuse the question but...how old are you?...i cannot believe tha someone can be so....well for lack of a better word..close minded...don't you have any imagination? How many times must i tell you that the actual level of the signal swing can only be about 5,4V? how many times must a tell you that the signal has a possitive and a negative phase and they alternate according to the signal, so even thow the peak to peak level it is about 10V ( or so ), the actual level of the signal swing cannot be more than 5,4V because the swing starts ALWAYS from the middle point and goes either UP or DOWN, it cannot go both ways at the same time, it can only go either possitive or negative from the middle point. If you still don't get it than stop wasting our time and go to school!!!
 30th June 2012, 12:00 AM #38 lazzer408   diyAudio Member     Join Date: Sep 2010 Location: Chicago 38 So your saying it only pushes 5.4v then pulls 5.4v at any time. It's not actually pulling the other leg up or down when it's swinging the first unless it's a BTL design. Right?
 30th June 2012, 12:04 AM #39 theAnonymous1   diyAudio Member     Join Date: Feb 2004 Location: Anonymityville Just give up Marian; don't get frustrated over this guy. If he doesn't want to understand why single ended output power from 12V is only about ~4.5W (low distortion "RMS", not even accounting for losses) then he can learn on his own. Just leave him with this..... Audio power - Wikipedia, the free encyclopedia
 30th June 2012, 02:11 AM #40 lazzer408   diyAudio Member     Join Date: Sep 2010 Location: Chicago I do want to understand. That's why I'm asking. If I knew EVERYTHING about electronics, I wouldn't be here. What's a forum for if we can't ask questions? I understand quite a bit about quite alot. Ever think your not explaining it right or leaving out key facts that explain how the output stages work? Grass is green, fine, I got it. Now explain WHY. Just saying 10w is 10w is 10w you only get 10w that's all you get is 10w. Trust me I'm on the same page. How I explain my interpretation may be as different from your understanding as your explination is different from my understanding. To get back to the ORIGINAL topic. What is THE highest power IC available using the least number of components that can do 2.1 in a single IC...... -or- ......2 ICs using a 2ch BTL + 1ch BTL to make a 2.1 system. Is the TDA1562 my best bet? Are there others you recomend so I can choose? Or do we want to keep arguing over power output? Last edited by lazzer408; 30th June 2012 at 02:18 AM.

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