Electronics > Beginners

Loud Speaker?

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ChrisGreece52:

--- Quote from: mariush on May 30, 2013, 12:55:45 pm ---
--- Quote ---The transformer in the picture is a 500mah 9 volt one but i will need more info about connecting it in parallel so i can increase the voltage

--- End quote ---
Dude...

You have voltage.

You have current.

Voltage multiplied by current gives you power.

That transformer is 9v  0.5 A  ... that's 4.5 watts.

No matter how many you put in parallel, the voltage remains 9v, just the current doubles, triples etc
No matter how many you put in series, the current remains 0.5A, just the voltage doubles, triples etc
9v is too low for a tda2050. No matter how much current you'd have by putting transformers in parallel, you still have just 9v.  If it starts at 9v, a tda2050 will only output about 1-2 audio watts, so the chip will only use about 3-5 watts (0.3-0.5 amps) out of how many amps your transformers in parallel would be able to provide.

If you put 9v transformers in series, you may have 18v, 27v, 36v ac or dc but your current will still be 0.5a
Let's say you put  3 in series to get 27v 0.5a. That's 13.5 watts. I don't know if it's 9v ac rms or 9v DC coming out of that. Let's just say 27v DC. 
If you go in datasheet at the graph, you look at +/- 13v (because the graph is for split power supply) and you see the amplifier chip has the potential to output up to about 7 watts. At about 60-70% efficiency, that means that to output a single channel (one amplifier), to output about 7 watts of audio, the chip will use about 10 watts.
Your 27v 0.5a will be enough, for ONE channel. 
If you put two amplifiers, one for each channel in stereo, they'll both use about 10 watts, 20 watts in total... but your power supply can only provide 13.5 watts.  Your power supply is undersized, even with 3 transformers of that type in series.

Do you understand the concept that the amplifier can not output audio watts if there's not enough power at the input? If you give it 10 watts from the mains, how do you expect to get 20 audio watts?

Use that 9v transformer for other stuff, it's not suitable for audio amplifiers.
Like I said, you need something like 24v AC rms 40-60 VA  (about 1.5A) to get about 20-25w of sound.

--- End quote ---
Well you will be happy for this !!!! i GOT IT finally i was confused (very confused) but now i got everything but in your reply sou said something that is well suited for me.
you said that if i connect 3 windings in series i will get 13.5 watts for power ... thats more than enough for one channel use :D
2 channels is optional as i said.

mariush:
nevermind. I read incorrectly and thought you meant parallel.

Anyway, it's just stupid to use three transformers, unless you already have them.

Just go buy a 24v ac transformer rated for about 20 watts at least, they should be cheap. Or.. I don't know, maybe find two car/motorbike batteries and put them in series to get 24v.

madires:

--- Quote from: ChrisGreece52 on May 30, 2013, 02:17:08 pm ---Something more usable its pretty old but still going strong
Its a Logitech X-420 2.1 system.
2 satelites and one subwoofer
http://www.newegg.com/Product/Product.aspx?Item=N82E16836121010
I got it for about 7 years .... ( i did not know that it has been so long ... )
good quality wooden woofer and i think it is the best i had (and the first i had :P )

--- End quote ---

I see. IIRC the satellites got a second passive speaker to boost lower frequencies. Those are ok for FPSs but lack a proper frequency response for higher frequencies. Midrange is "thin" and high frequencies are poor. But some people like that kind of sound. Just don't try to play classic music :-)

madires:

--- Quote from: ChrisGreece52 on May 30, 2013, 02:18:06 pm ---
--- Quote ---The 2" speakers will fall off around 100Hz very quickly, maybe even at a higher frequency.

--- End quote ---
well that sucks.......

--- End quote ---

That's why I recommend a 8" speaker. If you add a bass booster to your amp you'll get away with a smaller speaker (6"), but I woudn't go any smaller. Driving such a speaker with 10W should sufficient for a quiet midsized room. With a noisy background (talking people) you have to crank up things considerably.

ChrisGreece52:

--- Quote from: mariush on May 30, 2013, 02:40:18 pm ---nevermind. I read incorrectly and thought you meant parallel.

--- End quote ---
Thats ok :D

--- Quote ---Anyway, it's just stupid to use three transformers, unless you already have them.

--- End quote ---
No i do not have them but i thougth i could put 3 Windings in series (not transformers)

And

--- Quote ---Just go buy a 24v ac transformer rated for about 20 watts at least, they should be cheap. Or.. I don't know, maybe find two car/motorbike batteries and put them in series to get 24v
--- End quote ---
24v AC ??? you mean just a regular 220 Volt 50/60 hz to 24 DC right???
Also from another topic a member suggested that i whould look for the power the transformer can deliver so if i want a dual signal amp i am going to need at least 20 watts
Right ???

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