How strong does my amp need to be to power a 1-100watt 8ohm Speaker

zetorunt

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Nov 25, 2011
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I am making my own portable speaker with a KLH home theater speaker I have on hand using a chromecast audio. I am looking at a couple of amps but I want to make sure they are adequate. I don't need this thing to blast me away, just fill a normal sized room with sound at a reasonable level without distortion.

The first amp I have lined up is cheap, I know that. The RMS is only 2x4watts. But it doesn't need to blare, just fill a room and I like that it can power the chromecast.
http://www.amazon.com/dp/B006AMF2R8/ref=wl_it_dp_o_pC_S_ttl?_encoding=UTF8&colid=BQUTS60R346T&coliid=I13XTMW9KDPV9U

The second has a little more power and comes from a better name in audio:
http://www.amazon.com/dp/B0049P6OTI/ref=wl_it_dp_o_pC_nS_ttl?_encoding=UTF8&colid=BQUTS60R346T&coliid=I2TMLWDK91PE8W

Will these power my speaker well? If not, what kind of continuous wattage am I looking for?

As a seperate question. I have 2x 60watt 8ohm speakers I would like to use as computer speakers. WIll this amp suffice (I like it because it can power an old sony sub I have as well)?
http://www.amazon.com/dp/B0070Z87YO/ref=wl_it_dp_o_pC_nS_img?_encoding=UTF8&colid=BQUTS60R346T&coliid=I3NGATFCKNOTWU
 

koffeeshop77

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i doubt it delivers 15watts because Harmon Kardon is actually a pretty good brand and know for quality, addittionlay i belieave most manuacturs have higher wattage speakers than amps due to the fact that they dont want thier products to go bust after turning them up. alot of times it is not the speakers themsefls that make the sound but the enclosure they are in e.g. i have some pretty nice subs but if i where to put them in a tiny box or take out the bass tubes and seal them up to put it bluntly they would sound shit, no mater what amp i hooked them up to, and im talking some real nice pioneer speakers. fyi i build my own speakers, cuase i like to party and its a fun hobby. but im telling you those amps you listed wont do any good, its best to get one good amp and build off of that than have crappy amps and still wonder why the sound is bad, technicly you could still use you Harmon Kardon amp as a pre-amp and volume control while hook it up directly to the the other amp i listed above for 59$, that amp could run off of a pc power supply, and run whatever you had in mind no problem.
 

koffeeshop77

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Jun 9, 2015
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the first one dosent have near enough power, it will make the 100watts sound like tin cans.
the second one is quite a bit better, it wont blow your speakers, but if you look at the reviews on amzone it is also not made to drive 100watt speakers. at least with out distortion/the power suply that comes with it is too weak from what i read it more like a decent 10-15watts before distortion kicks in.

the only one i can really with good concenc recoment is the 3rd one, and even that has spotty reviews, but it will work for you needs. they are not built that well/sloppy so when you get it take it apart and double check the thermal past or you run the risk of a channel going out on it. (read review very easy task)

 

koffeeshop77

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in other words none of those will power you speakers very well, would be nice to know what you had in mind.

you are looking for countinus watts of at least 50, and that from a decent brand.
the one you picked are all e based on MAX 4/ 20watts. you need RMS 40-50watts output, with max of 100-120w peak. perticulerly for that driver.
 

zetorunt

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Thanks, thats kinda what I was expecting to be honest. I was trying to keep it around 12v 2-6amps though as its what I have to work with. I actually just tested out the amp on my Harmon Kardon computer speakers. I disconnected the leads from the driver and used alligator clips to connect the amp to the speaker I am trying to use. Not super scientific I know, but it did help me. The sound was not too distorted at lower volumes, which is what I was aiming for anyway. Im certain it wont win any audio contests but it was actually better than I was anticipating. I'm not sure it would suffice for me, but my gf wont be able to tell the difference. Unfortunately I cannot find specs on the computer speakers to know what they output. But given they are small I would imagine it was less than 10watts RMS. The sound was much fuller than I anticipated. So I am thinking, that maybe the Lepai would suffice.

Thoughts? These are my desktop speakers if it helps: http://www.ebay.com/itm/Harman-Kardon-Multimedia-Computer-Speakers-02320V-A-C-Adapter-12v-/151913901772?hash=item235ec62ecc
 

zetorunt

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Thanks for the help! I wonder if the amp in the base actually delivers 15watts. That would be pretty impressive given the chip has no cooling and is only about 2x3 inches. Not to mention the power supply is only 15v 1.1amps. Somehow I doubt they are getting more than 8-10 watts. Probably lower impedance than my KLH though.
 

koffeeshop77

Estimable
Jun 9, 2015
56
0
4,590
3
i doubt it delivers 15watts because Harmon Kardon is actually a pretty good brand and know for quality, addittionlay i belieave most manuacturs have higher wattage speakers than amps due to the fact that they dont want thier products to go bust after turning them up. alot of times it is not the speakers themsefls that make the sound but the enclosure they are in e.g. i have some pretty nice subs but if i where to put them in a tiny box or take out the bass tubes and seal them up to put it bluntly they would sound shit, no mater what amp i hooked them up to, and im talking some real nice pioneer speakers. fyi i build my own speakers, cuase i like to party and its a fun hobby. but im telling you those amps you listed wont do any good, its best to get one good amp and build off of that than have crappy amps and still wonder why the sound is bad, technicly you could still use you Harmon Kardon amp as a pre-amp and volume control while hook it up directly to the the other amp i listed above for 59$, that amp could run off of a pc power supply, and run whatever you had in mind no problem.
 

zetorunt

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Nov 25, 2011
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Yeah, I totally agree and will be going higher power for my desktop speakers. I like the look of that pioneer you linked, but now I have the itch to mix in an old 10" sub driver that's still in pretty good shape, so I'll have to re-adjust my power requirements. I figure, find a 2.1 amp, or, 2 separate amps. The one you listed and then a single channel sub amp maybe. I can get a breakout board for a comp psu and run them off the 12v or 24v rails like you said.

For the chromecast audio portable speaker, I am limited to 12v ~6a due to 18650 cell limitations (have a 3 cell carriage), so I will go as high wattage as I can and itl just have to do from there. That one is less important that it sound perfect. It wont be on very loud and it will be used as a background music device by my gf when shes working around the house/office. I think if I can squeeze 15-20 watts out of something it'l sound decent-ish. Good enough anyway. When I had her listen to the driver hooked up to the amp on my computer speakers she thought it sounded "really good." Its just an old 60w bookshelf speaker. So it was never going to be an amazing thing to begin with. Better than those small shitty bluetooth speakers you can get for $30 though.
 
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