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Chip Amps Amplifiers based on integrated circuits 

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1st May 2013, 12:41 AM  #21 
diyAudio Member
Join Date: Mar 2009
Location: Buenos Aires  Argentina

Thanks for actually building it, measuring, and post results.
Nothing against simulation, of course. 
1st May 2013, 04:27 AM  #22  
diyAudio Member

Quote:
Power ratings for amplifiers that are commercial products, in the USA, are required to have their power ratings measured and advertised in a certain way. Basically, they must advertise the continuous RMS power that one sine wave would produce, at below the clipping level. The maximum possible continuous RMS output power is totally limited by the supply voltage, or the supply current, for a given speaker resistance rating. So if you know either the maximum supply voltage, or the maximum supply current, and the speaker resistance rating, you can immediately calculate the maximum POSSIBLE output power, in terms of both peak Watts and RMS Watts. There is basically no way around it. Ignoring for the moment that the input power supply voltage would need to have subtracted from it: the ripple voltage and the amplifier dropout voltage, and a diode voltage drop or two if it's an AC power input, lt's assume that an amplifier has plus and minus 40 Volts DC to work off of (most amps are powered by both positive and negative voltages), and won't clip at that voltage. So for now we're saying that the output can swing to +40 and 40. [With only one supply, + or  but not both, just cut the following numbers in half.] First, you have to find the maximum RMS sine output voltage, by dividing by 1.414. SO that's 40 / 1.414 = 28.2 Volts RMS. Then, use the formula for RMS power: Watts RMS = Vrms x Vrms / R_speaker. So for an 8Ohm speaker, that would be 28.2 x 28.2 / 8 = 99.4 Watts RMS (actually, it's 100 Watts RMS, but I roundedoff the square root of two to 1.414). With 40 Volts, it would be literally IMPOSSIBLE to get a higher continuous RMS power output level into 8 Ohms. And, for 4 Ohms, 2 Ohms, 1 Ohm, it would be higher (2x, 4x, and 8x higher). PEAK power is calculated the same way, except you just start with the peak voltage, instead of the RMS voltage. It turns out that the maximum possible peak power is always exactly 2X the maximum RMS power: Watts peak = Vpeak x Vpeak / R_speaker = 40 x 40 / 8 = 200 Watts peak. As far as the present discussion is concerned, there is NO WAY to get more than that, with a 40V DC supply and an 8Ohm load. But, lo and behold, with 2 Ohms, that would be 800 Watts peak. But, of course, from that 40 Volts, in reality, you have to subtract at least the ripple voltage and the amp's dropout voltage. Even with monster capacitors that make the ripple voltage really small, there's no way around the dropout or "clipping" voltage, which might typically be 3 to 4 volts. So, for +/40 Volts DC in, you would only be able to get something like 36 or 37 Volt peaks, at the output, at the very most. So you would calculate the maximum power with one of those, or the actual maximum output voltage swing. Last edited by gootee; 1st May 2013 at 04:33 AM. 

1st May 2013, 09:14 AM  #23 
diyAudio Member
Join Date: Jul 2004
Location: Scottish Borders

The arithmetic is so simple that any school child can check adverts to see if the retailer is telling lies.
Don't automatically believe all you read/see. Analyse, at least to the most basic levels, to determine whether you want to use the information in a real life situation.
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regards Andrew T. 
1st May 2013, 12:15 PM  #24 
diyAudio Member
Join Date: Mar 2009
Location: Buenos Aires  Argentina

@ frogg:
all this can be resumed in: what the boosted 7294 amp claims is **IMPOSSIBLE** . You may claim "but it works!!" Well, maybe it does, sort of .... but definitely not the way he claims !! 
1st May 2013, 03:22 PM  #25 
diyAudio Member
Join Date: May 2011

now that i know something new
the transistor he used to build that amp useing the tda 7294 amp can it be used in this tda 2030 version if it can will it improve or will be the same output 
1st May 2013, 04:32 PM  #26 
diyAudio Member
Join Date: Jan 2006
Location: Athens GREECE

2cents
Numbers will work on bench for this IC and circuit ( bench= 1KHZ @ resistive load 48R ) but never in real life since real life speakers are inductive loads and internal limiting of the IC will behave accordingly . Still if you take a closer look you will see that this is also a form of sziklai style circuit which will produce nice sonics and harmonics only up to the quality of the IC ,and prove to be extremely tolerant to even demanding types of music or speakers or long cables . To be more specific external transistor will bother with the current demands while the Ic will play the music Kind regards Sakis
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SERVICE ΕΝΙΣΧΥΤΩΝ ΚΑΙ ΙΑΠΩΝΙΚΩΝ ΜΗΧΑΝΗΜΑΤΩΝ ΗΧΟΥ www.eastelectronics.gr Last edited by east electronics; 1st May 2013 at 04:47 PM. 
2nd May 2013, 10:30 PM  #27 
diyAudio Member
Join Date: May 2011

ok
so the ic plays the music and the transistor adds a lil more current to it i notice that while i was looking at the diagram the music signal never flow through the transistors hmmm is there way to make it so the sound passes through the transistors while i was researchin amps i came across some small amp build diagrams i will post it when i get some time 
2nd May 2013, 10:46 PM  #28 
diyAudio Member
Join Date: Mar 2009
Location: Buenos Aires  Argentina

Ah! .... but the music does pass through the transistors, they're the muscle.

3rd May 2013, 01:06 AM  #29 
diyAudio Member
Join Date: Jan 2011

What's the role of those diodes on the output??

3rd May 2013, 02:33 AM  #30 
diyAudio Member
Join Date: Jan 2006
Location: massachusetts

Diodes are for protection  to avoid excessive reverse voltages across the output when circuit is shut off with reactive loads. They don't have any effect on audio.
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Steve 
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