Build Your Own Arcade Controls Forum
Main => Audio/Jukebox/MP3 Forum => Topic started by: gatordad on October 10, 2007, 02:09:34 pm
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I have a 2 channel 20watt amp that I am going to use.
I am now ready to buy some speakers.
Before I pull the trigger I have a question as speaker specs are beyond my knowledge limit.
If a speakers specs say that the RMS is 110w and max is 220w.
Would my 20watt amp be enough to drive that speaker.
Its this set I am considering
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=320164940326&ssPageName=STRK:BHWA:US#ebayphotohosting]
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yes. if you feed the speakers 20w, then it should output 20w.
additional:
it can be safely fed with a steady signal (sine wave) of up to 110w, but since sound is has irregular bumps and dips, those speakers can take up to 220w for brief periods. keep your amp up to 110w rms only. this is just a practical view.
more additional:
consider your amp as well. rms value (root mean square) is a mathematical calculation of the nominal or steady power output. this is the rating that you want and not pmpo (peak music power output) which is deceptive. on a ten scale vu leds, pmpo would be all leds lighting up momentarily at the bang of a drum while rms is a more constant 3 or 4 leds for the rest of the song.
my $5 amplified pc speaker is advertised as 200w pmpo yet it contains a 2w chip.
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Max rating on that speaker at 220w is peak music. Effeciency of the speakers has alot of factors, typically 20w in will not get you 20w out. General rule of thumb is your speakers need to be twice the output rating than the amp. Speakers that have higher power handling specs will require a minimum amount of power to rated specs of what the speaker can produce. So basically a bass speaker that is rated for 200w you will not get much bass sound until a minumum power output is reached, it needs that minimum to move some air. On homemade speakers you can port the speaker for more bass response at lower volume.
The amp you are talking about that only puts out 20w is not going to effeciently drive that speaker. About the time that it meets the minimum requirement the amp is almost at full power and you will be getting alot of distortion. You want an amp that has some head room. Let's say you have a small room you are putting the juke in and it only takes 15-20watts ti fill it then you typically want a 50 watt per channel amp. That allows you to turn the amp up to that 15-20w and not saturate the amp into distortion. I would not use 200w speakers in a small room, if you use the 50w amp than 100w speakers would be fine. Also with the headroom you have with the amp the sound quality is so much better because you are not saturating the amp.
You have to watch ratings on powered speaker systems these days because for example if it is a set of computer speakers they will list it as 100w but that is input power to operate the speakers not the output of the speakers. This is a way of tricking the consumer into thinking thier getting more than what you are. Every speaker manufacturer does it and it doen't make any difference of the price range.
A truly good sounding homemade speaker system requires some homework, it's not just cut a hole and stick it somewhere.