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PostPosted: 02 Jun 2016, 04:31 
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Location: India
Hi Everyone,

Hope all for you are doing good!

I need one help to built a 2.1 sound system. I will be using normal speakers only which will be enough for one room. I want to build it from the scratch.(Circuit)

I bought the following items:- :sing:
3 x TDA2030A power amplifier and 1 x NE5532N dual OpAmp
1 x sub-woofer: 4 ohm, 25 watt
2 x mini-speakers: 8 ohm, 0.25 watt
Register and Capacitor not yet decided. :confused:

I googled the circuit for 2.1 sound system i got the circuit diagram with all the component list : http://xtronic.org/circuit/amplifier/circuit-power-audio-amplifier-with-tda2030-2-1/. But the problem is that the output rating for the given circuit is way higher than my requirement (3x18 watt). :geek:

I need to complete this project as soon as possible.


Regards,
Ravi

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PostPosted: 04 Jun 2016, 06:53 
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Hi,

Any one, can you please help me with this project. I am new to this this forum, also to this domain.

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PostPosted: 29 Oct 2016, 05:07 
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Did you complete the project Ravi?

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PostPosted: 30 Oct 2016, 02:06 
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Richie wrote:
Did you complete the project Ravi?


Hi Richie,

Not yet. Still trying to figure out how to cope up with the amplifier output so that it won't burn my speakers.

Do you have any existing circuit that I should work on! :xfingers:

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PostPosted: 17 Nov 2016, 14:48 
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ravi.bppimt wrote:
Richie wrote:
Did you complete the project Ravi?


Hi Richie,

Not yet. Still trying to figure out how to cope up with the amplifier output so that it won't burn my speakers.

Do you have any existing circuit that I should work on! :xfingers:


OK - some basics on speakers and amplifiers:

a) Speakers are not "Pull" devices and amplifiers are not "Push" devices. What this means is that a 25 watt speaker will not "PULL" 25 watts nor will an 18 watt amp always "PUSH" 18 watts.
b) A speaker rated at some power level can accept that power level all day and all night (theoretically) without failure. The reality is some formula of power-over-time that averages at 25 watts - but is still a LOT more than you will be delivering on-average. I am feeding 75-watt speakers with a 200 wpc amp with no worries at all. The amplifier is capable of delivering about a 400 watt peak for 1 second without distorting, and the speakers are more than capable of handling this as well.
c) If you completed project is stable, and you are feeding it a clean signal, you really have no worries at all using conventional speakers.
d) You are not using conventional speakers.

Now, cutting to the chase and your 0.25 W (250 mw) miniature speakers: You will need a substantial resistor in series with these speakers to damp the amp to the point that you may safely operate the speakers together with your sub and get any sort of volume from the sub. And that resistor might get quite warm. But, let's try and sort this out.

I have a Koss headphone switch designed to connect directly to speaker outputs. Inside is a 100 ohm, 5-watt resistor in series with each channel. This box is designed against headphones typically rated at 250 mw @ 250 ohms. As you are also driving a subwoofer, you want to be able to run at the maximum your amp can deliver (18 watts) The 'box' with a 100 ohm resistor gives you that, or about 22+/- watts rms from the amp giving 250 mw for the speakers.

Which would suit your speakers nicely.


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PostPosted: 01 Mar 2017, 07:59 
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Hi Peter,

Thank you very much for clearing the most critical doubt I had. :thumbsup:

Can you please suggest. I am using the following circuit : https://xtronic.org/circuit/amplifier/circuit-power-audio-amplifier-with-tda2030-2-1/. What will be the output impedance of each speakers?

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PostPosted: 01 Mar 2017, 09:07 
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Ravi:

All the output measurements are taken at 4 and 8 ohms. Hence the need for a dropping resistor to the speakers if you are using those tiny little speakers. If you use conventional speakers of 4 or 8 ohms (nominal) impedance, you will be fine.


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PostPosted: 20 Mar 2017, 22:51 
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If I understand your post correctly you could use one of these: https://www.parts-express.com/variable-low-pass-filter-electronic-subwoofer-crossover-preamp-board-with-gain-control--320-670 This has a variable low pass and separate gain knob for the subwoofer. This is a preamp only.

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PostPosted: 21 Mar 2017, 20:14 
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Also, here is a basic video that shows how to hook up a 2.1 system from scratch. maybe this will help.

https://www.youtube.com/watch?v=TvbkwwLSRvE

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PostPosted: 23 May 2017, 13:13 
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Peter W. wrote:
Ravi:

All the output measurements are taken at 4 and 8 ohms. Hence the need for a dropping resistor to the speakers if you are using those tiny little speakers. If you use conventional speakers of 4 or 8 ohms (nominal) impedance, you will be fine.


Thank you for the suggestion.
I made the circuit and tried to drive the same using 12-0-12/3 Amp transformer. I feed the Audio input to the circuit and switched on the power supply. But I got zero output from the speakers. After 2-3 secs, 7912 negative voltage regulator got fried :hot: :hot: . The I disconnect the power supply at that instant. :(

Is there anything you could help me with that. I have attached the doc which I referred to make the circuit.


This post has a file attachment. Please login or register to access it. Only Registered Members may view attached files.


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