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help with a pair of 10W computer speakers

Tom Nixon

Sep 19, 2014
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hi there, i am considering adding a more speakers to a pair of 10W computer speakers and i'm not sure how much wattage to add, any help would be highly appreciative
 

Arouse1973

Adam
Dec 18, 2013
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Whats the output of the amplifier. You cant just add additional speakers you risk overloading the amplifier. You can add smaller speakers that add up to the total output power of the amplifier. What are you trying to do?
Adam
 

Tom Nixon

Sep 19, 2014
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i am really not too sure what the output is, all i know is the speakers are 5 watts each, and i thought you could add speakers up to like 10% over the size of the amplifier and plus i'm not sure how to check the size of the amplifier, however they are computer speakers so i'd imagine they are quite small
 

Gryd3

Jun 25, 2014
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This is what may happen if you try to drive something that is too large.
Wheels too big for Engine.
Speakers too big for Amp.
Results could be similar.

*(Sorry, couldn't help it)
 

Gryd3

Jun 25, 2014
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i couldn't watch that, i had an error, could you elaborate?
Lots of smoke, followed by a little flame.
It's never a good idea to try to drive a load that is too large for the amp or other power source to handle.
The 10% you mentioned above is acceptable, if you know what your speaker's amp is rated for...

You may be stuck with having to use a 3.5mm y-adaptor to run two sets of powered speakers.
(I've done this to get audio out of 3 sets of speakers... tricky part is adjusting all the speakers to the same volume and leaving them like that)
 

Tom Nixon

Sep 19, 2014
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ok so i guess your point is, if the speaker is too big for the amp there isn't enough voltage to power them
 

Tom Nixon

Sep 19, 2014
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do you happen to know how i would measure the amplifier rating, like for example measure how much capacitance is in the circuit or how much resistance the circuit has in relation to the main voltage? if indeed it is what i just said i know Ohm's law, learnt that at college
 

Gryd3

Jun 25, 2014
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do you happen to know how i would measure the amplifier rating, like for example measure how much capacitance is in the circuit or how much resistance the circuit has in relation to the main voltage? if indeed it is what i just said i know Ohm's law, learnt that at college
I don't know of any tricks to determine that unfortunately...
You may be able to get a ball-park figure by looking at the power supply.

When you try driving a bigger load than it's built for, it's not just the simple fact that there is not enough voltage. You end up messing with the impedance matching which causes more energy to be wasted as heat in the amplifier.
If you've learned ohm's law, then you are familiar with voltage dividers, correct?
If you have two equal resistors in series, they both dissipate the same amount of energy.
What happens to power through the first and second resistor as you increase or decrease the resistance? (First resistor is the Amp, and second is the collection of speakers that are connected)

Bit of homework if your interested. It should help show you what will happen if you add extra speakers.
 

davenn

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Sep 5, 2009
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Hi Tom
welcome to the forums :)

Tom Nixon said:
do you happen to know how i would measure the amplifier rating, like for example measure how much capacitance is in the circuit or how much resistance the circuit has in relation to the main voltage? if indeed it is what i just said i know Ohm's law, learnt that at college

The amplifier should have labels on it giving the output rating per channel

what is the make and model of the amplifier ?
Have you googled that model number to see if there is info on the net ?
 

Tom Nixon

Sep 19, 2014
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hi thanks, it's not exactly an amplifier, they are computer speakers so they have a small amplifier inside,(I IMAGINE) and as for googling the amplifier, i'm not exactly sure what i'm googling
 

Tom Nixon

Sep 19, 2014
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ok i did some tests that i don't quite understand, i tested the voltage at the main power point i got 4.35V, measured the resistance at the same point and got 1kΩ, meaning that the amperage is 0.00435A which i think is 4.3mA, P = I2 x R so I2 is roughly 0.07A and the power is 70W which if that's true it means i can put my speakers on there but i can't believe the amp is that powerful
 

Gryd3

Jun 25, 2014
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ok i did some tests that i don't quite understand, i tested the voltage at the main power point i got 4.35V, measured the resistance at the same point and got 1kΩ, meaning that the amperage is 0.00435A which i think is 4.3mA, P = I2 x R so I2 is roughly 0.07A and the power is 70W which if that's true it means i can put my speakers on there but i can't believe the amp is that powerful
Props for the attempt Tom, but the input resistance of the speakers won't be accurate or reliable.
The reason being, that the internal power supply for the speaker's built in amplifier will change it's effective resistance as the circuit demands less and more. The best source for this info is looking on or beside any power plugs or jacks and seeing if it will tell you an input voltage and input current. (Or output voltage and current if you have a DC wall adaptor)

From what was mentioned earlier, the amplifier we are referring to is the internal amplifier circuit built into the speakers. It may not say the power on the device anywhere, but it should at least have a voltage and current rating.

Without knowing, or being able to determine a guess at least, we can't recommend any reliable methods to add additional speakers.
One other note to add... Even if you add additional speakers, you may not get any additional volume as the amplifier that is in there is most likely loaded to, or pretty close to it's max rating.
 

Tom Nixon

Sep 19, 2014
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i understand that i may not get extra volume (maybe a couple of decibels at that) i was thinking it could distribute the sound a little bit better, also i was considering adding a secondary amplifier to power the extra 60 Watts coming into the circuit, which as i understand it could or possibly will take the extra burden and strain off the existing amplier and speaking of the existing amplifier, i found an IC inside the circuit, looks like a 16 leg Ic, which by the looks of it, ties all the other components together, the computer speakers are "Trust Mila 2.0 computer speakers"
 

Gryd3

Jun 25, 2014
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i understand that i may not get extra volume (maybe a couple of decibels at that) i was thinking it could distribute the sound a little bit better, also i was considering adding a secondary amplifier to power the extra 60 Watts coming into the circuit, which as i understand it could or possibly will take the extra burden and strain off the existing amplier and speaking of the existing amplifier, i found an IC inside the circuit, looks like a 16 leg Ic, which by the looks of it, ties all the other components together, the computer speakers are "Trust Mila 2.0 computer speakers"
Adding an additional amplifier could cause some issues depending on how you hook it up...
If the additional amplifier is connected to the new speakers only, you should be good. If you tie both amplifier outputs together, you could run into current loops where one amplifier is backfeeding into the other.

I take it you took apart the speakers.
If you can provide some nice clear pictures and tell us the numbers on the components, we can try to determine what it can handle or setup for.
 

davenn

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Sep 5, 2009
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Ahhh OK :)

well it says they are powered from the USB port with is 5V at an absolute max of 1A. so that's a possible amplifier output of 5W and that is excluding losses which will exist

so you in reality may be getting around 2W per channel

their claims of ...
Item specifics

Type:
Speakers
Max Power Output:
10 - 20W

is utter rubbish!! as is common with many claims from domestic amplifier sales

Dave
 

Tom Nixon

Sep 19, 2014
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okie doke, doesn't necessarily explain why they have two 5W speakers on each side with an impedence of 4Ω commonly associated with car speakers, and i still don't know what to do, whether to get a secondary amplifier, maybe a small 30W amp, just to balance it out, because my idea is to build it as a mobile speaker for such occasions as going on holiday
 

Tom Nixon

Sep 19, 2014
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ok i have thought of an alternative, seeing as higher wattage doesn't really increase volume, or make much of a difference whatsoever, i checked my collection of the thousands of speakers i have lying around my room, and i thought i could add two 4W speakers instead, any thoughts on that?
 

davenn

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Sep 5, 2009
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if you want more sound out with the ultimate aim to spread the sound better around the room. The best thing would be to get another small amplifier something in the 30 - 50 Watt per channel range. Maybe look for one that also has a sub woofer out and can handle say 4 speakers ... ie. front and rear speaker sets

maybe a 5.1 system ... they are pretty cheap these days, a lot of people buying them to add extra sound to their big screen TVs

Dave
 
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