How to couple pairs of computer speakers together to increase volume?

Problem: laptop speakers are too quiet

Proposed Solution: couple a few pairs of computer speakers together to increase the volume
-I have not worked with audio-electronics before is this possible/plausible?
-computer speakers need 8ohm resistance (T/F)?
   -if true when I split the lines do I need to increase resistance?
-non-powered vs powered computer speakers?
  -if I go powered can I use a small voltage (5volts) amp to power them?

NOTE: I really have no experience so if the scheme below is completely ridiculous let me know, and try to point me in the right direction. I just want to hook a few pairs of computers speakers together.

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NachoMahma6 years ago
.  If you want more volume, you must have more power. Get some powered speakers.
+1. More speakers is likely to result in less total volume, since the available power has to be split among them (and the resistors are wasting yet more power). External amplifier, either in the speakers or as a separate unit, would be a better bet. Used stereo-system amps can be had cheap-to-free if you find folks who are upgrading their systems.
gmoon Re-design6 years ago
This is flat-out incorrect.  Multiple speakers are louder.

Using two speakers (instead of one) for a given output power increases the "sound pressure level" (SPL) by 3dB. Three decibels is analogous to twice the output power .

Citations: music center, and the excellent MEF forum has dozens of threads about this (some slightly ill-tempered :-)...

That doesn't mean twice as loud, though. Doubling the output power might be barely noticeable. It's widely accepted that loudness is logarithmic -- it requires TEN times the power to sound "twice as loud." And of course, the two (or more) speakers together MUST have the correct impedance (load) for the amplifier for this to work.

. PowerOut = PowerIn. It doesn't matter how many speakers you hook up, the amp can only put out a certain amount of power.
. Granted, if you have set the volume control for, say, 10%, then hooking up another speaker will be somewhat louder, but the maximum output of the system will remain the same (in real life there will be some minor variations, due to the non-linear impedance curve of speakers).
. And, as you note yourself, one runs into all sorts of impedance problems when connecting more speakers. This can cause much distortion. More volume under some conditions, but not really more music.
Read (in depth) about SPL and multiple speakers. I won't argue the fact about more speakers==more volume, because it IS the "text book explanation."

The science behind this is beyond me, but apparently the "directionality" of two speakers has much to do with it.

And any scholarly explanation of cabinet design will cite this.

You will notice, if you read the MEF forum, that MANY people want to disagree with this. Usually for the same "conservation of energy" reason, which is a potent argument. I included the MEF links specifically because some of the (VERY knowledgeable) posters there don't want to agree, but they cannot refute it...

I could post MANY more citations.

Would you please provide some for the opposite POV? (other than the MEF discussions). One that specifically refutes it, with data?
. At least one of us doesn't understand the explanations given at the links you provided.
. Or maybe we're talking apples and oranges. You (and some of the commenters at your links) seem to be talking about how an amplifier may respond to a lower impedance at "normal" listening levels (and using an amp that will handle the decrease in impedance) and I'm talking about total volume out at maximum rated power.
. Yes, just throwing another driver into the system can increase the volume if the amplifier will handle it - the impedance drops and the amplifier puts out more power.

> Would you please provide some for the opposite POV?
Here's one. It doesn't matter if you have one or one million drivers, you cannot get more power out of the speakers then you put in. If it gets louder, then you are using more power.
Where the data specific to the question? We ARE talking about loudness (not power), which is a peculiar  thing.

Obviously, whatever happens acoustically (correlation,multi-speakers counteracting lower speaker efficiency at higher volumes, whatever) , it doesn't violate CofE. Conservation of energy aside, this is still "textbook acoustics." 

You can read the links, and try to understand them (I don't--fully at least).  Or buy an SPL meter at Radio Shack and try it yourself.

If you find this answer incomplete or unacceptable, that's fine. Read what's available (or not).

(Impedance is a red herring. Anyone who builds, buys, and uses multi-speaker cabs knows how to achieve the speced impedance with the correct choice of speakers in parallel / serial. Not that people don't experiment, occasionally, but that's not the norm, and it's not what we're discussing. Anyone who changed the load impedance and heard a change would suspect that first.)
> We ARE talking about loudness (not power), ...
. And there is a direct correlation between power in and loudness out.

> ... which is a peculiar thing.
. What's so peculiar about logarithms?

> Impedance is a red herring.
. How so? It has a direct affect on power which directly affects loudness.

> Anyone who builds, buys, and uses multi-speaker cabs ...
. I built several such speakers back in The Good Ol' Days. But what has that got to do with the situation at hand? The OP's only "crossover network" is a resistor or two at most. In all my experimenting, I never got more sound (or at least not a noticeable amount) out of a multi-driver speaker. If I was using a crossover, I always got less sound.
Err. I posted a reply. And then removed it.

Anyhoo, it's not really productive to my time, and I've had about enough of this awful "rich" editor for a several days to discuss this anymore. At this point, it's seems like just "arguing to argue," and that's worthless to me.

Google it yourself, if you don't believe it.
gmoon gmoon6 years ago
I should add one more comment, regarding impedance (red herring), because overnight I realized what you're speaking SS and I'm speaking tube.

I've been assuming a "level field" for impedance because for tube amps there's an optimal load resistance. Increasing or decreasing the load doesn't increase power output (see the chart below I already had in my library.)

Not so for some (Solid State) amps. Increasing the load from the nominal point WILL increase the power output.

However, the audio output for doubling the speakers WITH an impedance change for SS amps is an increase of 6dB, not the 3dB seen when doubling with same load impedance.

In that case-- twice the power, twice the SPL==6dB.
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DELETED_aChilNors (author)  gmoon6 years ago
Thanks for the responses everyone. You all helped show me how little I know lol.
Anyway forget the diagram I'm just going to mix some powered and un-powered speakers, splitters. and some 'custom' ; ) amplifier(s) and tweak the set up till it works. I'll let you know how it goes. Thanks for all your help.
Re-design gmoon6 years ago
I agree that the numbers say you will get an increase in sound. I'm speaking of an actual situational increase in noticeable sound since the question is about heard sound not theoretical sound.

3db increase is not enough of an increase to be hardly noticeable at normal listening volume for most people.

Unless the speakers are high efficiency you probably would not even get a 3db increase and more power would be lost thru inefficiency.

So, we're both right just looking at different sides of the same question.
gmoon Re-design6 years ago
Theory aside, I completely agree that multiple speakers probably won't get the volume desired by the OP.

However, if the original speaker is really bad / inefficient, then any decent replacement (single or multiple) might offer a noticeable improvement. Sustituting a nice 12 in. speaker for a crappy 3 in. model will be better / louder ('course, I've got 6 or 8 ten and twelve-inchers just sitting around...most people don't, so that's an unrealistic suggestion).

And there are super-efficient modern speakers that offer 5 or 6dB improvement over average speakers. But they are not cheap. The simple advice is the best--use some amplification. Again, theory aside, I don't (and didn't) take exception to that. NachoM's answer is good,
ARJOON6 years ago
affter splitting wtth the first 2 resistors the next 2 resistors should be 2ohms.
make sure you use resistors that are rated 5w or above else it will melt, only if you have same tyoes of resistors and it wil usually not be necessary

you are putting resistors so that different speakers match up. if you have 8ohm speakers and others are 16. connect ressistors across 16ohms one to match thee 8 ohms and then paralleling the speakers.

another more simple way is to connect it to an external amplifier that runs from mains voltage no resistors will be needed then. the usb amp will drain ur battery much quicker and heat up the usb port alot thus lowering lifetime of your laptop