If I have a 1000watt stereo with 5 speakers, and I add another 5 speakers, what will the effect on volume be?
Will it be twice as loud, because there are twice as many speakers? (Or maybe just a net increase in sound, not necessarily a 100% increase.
Or will it be half as loud because there is twice the speaker load? (Or at least just a net decrease in sound?)
Or will the increase and load and increase in speaker number cancel each other out and there will be no increase in total volume??
If you’re doubling the speakers, you can either hook them up in series or parallel with the old ones. In series, you double the impedance, reducing the load and volume a bit. If you put them in parallel, you halve the impedance, theoretically doubling the current draw and increasing the volume by 3db which is just a bit. In some cases if the speakers are close to each other that acn increase the sensitivity and make it a bit more.
However that’s only if your amplifier will deliver the current. First you need to check the specs and make sure it can handle half the impedance of one of your speakers. Also you should see if its power at that impedance is twice that at the original impedance. Many amps won’t double their power because the power supply isn’t big enough, so you won’t get 3 db more sound.
Sound quality could be worse if the amp can’t handle this increased load. Also, if you just stack them or something to get more sound, you’ll get interference effects from having multiple sound sources close together at the same frequency and that can hurt quality. If they’re horn speakers this might not be a problem if their patterns don’t overlap.
This all assumes the new speakers are the same as the old. If they’re different then all bets are off and the sound quality could be degraded and the load on the amp could be wierd. The real question is, why oh why do you need more? Is this at home?
Just kinda curious. I upgraded my home theatre surround sound. And while thinking of what to do with the old system, I started thinking about the speakers. Then I started wondering about this question. Not because I want to add them, but because I was really curious about the effect. At first I though, “It will not be as loud, because each speaker will be half as loud as it could be. And two speakers half as loud, will not equal one speaker twice as loud… or something”
So before posting here, I had convinced myself that each speaker would be half as lound as it should be. But since there was twice the number, the net effect would be close to 0db.
By the way, unless you’re using professional PA amps, or expensive audiohile amps, you’re might not be getting 1000 watts. Home-theater receivers don’t have standardized power ratings like stereo receivers. One might say 5x100 watts, but that only means that any one channel can make 100 watts, not all at once. The “1000 watt” receiver may output 300 watts or less total. Also a home-theater receiver is unlikely to double its power with a doubled load.
If it’s legit it will be rated “all channels driven” and weigh about as much as a boat.
Aw fuck! what a jip!!!
So is that why a 1000watt Sony home theatre sounds so much better than a 1000watt Generic? Maybe the Generic only has one channel putting max watts at any time? How lame!
I didn’t buy a generic. But still… if my sony says “1000watts” then that’s what I want, damnit!
[audio guy drooling hijack]
Check out Crown’s I-Tech amp series. The largest, the I-Tech 8000, puts out around 4000 watts per channel. I’ve heard stories of these suckers being run bridged and putting out 10,000 watts into a 4 ohm load. The kicker? They only weigh 28 pounds each. This is compared to their Macro-Tech series, where the largest puts out 2500 watts per channel and each one weighs 77 pounds. Oh, and the I-Tech has onboard DSP as well and will soon be able to accept a digital audio protocol called Cobranet that runs over standard cat5 cable, as well as with your standard routers and switches. Pretty sweet, right?
For some other high power/lightweight amps, check out Lab Gruppen and some of the other manufacturers you are likely to find on the major tours.
[/agdh]
Okay, I neglected to mention Class-D amps. They can put out a whole lot more power for their weight, but I haven’t heard of any home audio ones yet except for the little tiny Sonic Impact T-amp.
I wouldn’t feel ripped off because you don’t have 1000 watts. Most HT receivers aren’t rated all channels driven. If it’s a conventional class AB amp, the heavier one will be more powerful usually. I don’t think there’s a need for 1000 real watts in most homes.
There exists a very real chance the volume will plummet to zero if the amp can’t source the current and you blow either the final stage or a fuse. Remember that a power transistor is a $2 device that will protect a 25¢ fuse by blowing first. (old electronics joke)
If you put identical speakers in series, each will receive half the current it was, resulting in one-fourth the electrical power consumption in watts per speaker. Don’t look at me like that - it’s the fault of Ohm’s Law: Power=Current squared * Resistance)
If you put them in parallel, you’ll see a doubling of output current and of consumed power. If you put three speakers in parallel, you’ll have a net tripling of power, but are at risk of blowing something. Some amps can happily play all day long into a 2.6 ohm load and not even start breathing hard, but others (and by others, I mean most consumer amps with amplifier modules, as opposed to discrete transistors) will suffer a catashrophic leak of the magic smoke that makes them work.
If I plug both speakers into the ports on the back of the receiver, that’s Parellel, right? and if I plug on striped wire from one speaker into the receiver, connecet its plain wire to the striped wire of another speaker, and then the plain wire of that speaker, then it’s in series, right? Or is that backwards? Or totally off?
You’re correct on the parallel/series connection. There’s usually no good reason to connect multiple speakers to one amplifier channel (the only common one I can think of is using car speakers (nominally 4 ohms) in a home system (nom. 8 ohms) ).
On the subject of how much power you’ll find sufficient:
Speakers are rated by their senstivity, which is essentially their efficiency in delivering acoustic power for electrical power input. The ‘typical’ effeciency is around 90 dB SPL (1 W/1m), which means you get 90 dB Sound Pressure Level (this is the dB most people are familiar with) 1 meter away for 1 Watt [sup]*[/sup] of input. Every doubling the power adds 3dB SPL.
Thus if you actually had 1000 W coming out, you’d have 90 + 3* log[sub]2[/sub]1000, or about 120 dB SPL at one meter. This is easily enough to cause permanent hearing damage and possibly even pain if you listen at that level.
In general, most people listen to music at much lower (and more comfortable) levels. A modest amount of power is required to prevent distortion on the peaks, but it’s not too bad.
[sup]*[/sup] Often the value 2.83 V is used, which is 1 W at the nominal 8 ohms. The senstivity is measured at some frequency, often 1 kHz.
Some of the new digital amplifiers are going to be putting out very strong power at a very low unit weight and heat output.
some rules of thumb—all other things being equal, of course–
Doubling power increases SPL by 3db
Doubling speaker cone area increases SPL by 3db
Increasing power 10x doubles SPL (which is a 10db gain)
A real world demo of the above-
I currently have 1 SVS 16-46pc+ home theater subwoofer. It has the 12.1 series subwoofer speaker. SVS has just released the 12.3 version. By upgrading from my .1 to the .3, I will gain 3-4db. I plan to add a second 12.3 identical sub. This will mean I gain 3db by doubling the power I have now(575RMS to 1150), another 3db from doubling cone area, and another 3-4 since the new sub will also have the 12.3. I should see 12-15 additional dbs, which would be a volume increase to my ears of 2-3x what it is now.
If you put speakers in parallel like this and run them in the same room, you’re probably messing up your sound anyway. Two drivers of some random distance apart, outputting the same signal could easily cause all kinds of interference and standing waves with each other. You’re not making your stereo better this way, and you’re not getting true surround sound. And you probably risk damaging your amplifier.
Not that if a speaker is rated as being 8 ohms, that’s not what it’s presenting to the amp all the time. The impedence of the speaker will vary with frequency. Some 8 ohm speakers go as low as 2 ohms. Put those in parallel on an amp that can’t draw the current, and you could blow fuses, destroy circuitry, or just drive everything into distortion so it sounds like hell.
Actually, there are a number of rather inexpensive digital amps on the market now, and they apparently perform very well for their size and cost. The Panasonic XR55s is a 7.1 channel digital receiver with DTS decoding for around $250.