Explain amp wattage for me.

[Billy S]

Can someone please explain something for me concerining amp wattage.

If I buy an amp that is a 5 channel, 200 watt per channel amp (Emotiva xpa 5). And 3 of my speakers are good to 200 watts and my other 2 are good to 150 does it try to push 200 to the 150 watt speakers or does it stop it at 150? Or should I go with a 7 channel, 125 watts per channel. I don't even know if I'm making any sense here, but was trying to find some answers.

A guy at a local shop here was trying to sell me a lexicon ( if that's even the right name) and said it would make a world of difference in how my system sounded.

Here's what I've got.

Onkyo 705
Infinity beta 40's
Infinity beta 360 center
and Infinity beta es250 dipoles.
I've also got 2 Infinity beta 20 bookshelfs for speakers in my zone 2 on my receiver.

Can anyone help me here....

Thanks

 

[jamie2112]

The xpa-5 is a great amp and the company has a good reputation. The wattage is not really going to run at 200 watts all the time. Your rear speakers ie; 150 watt pair will be fine as long as you are not running full blast. I am sure you won't have any problems with the Emotiva. I am not familer with your onkyo but is it a HT receiver and how many channels is it?

 

[Adam]

Billy - Jamie is right. You shouldn't have any trouble, especially if the speakers rated at 150W are your rear speakers. The rear speakers don't get as much sent to them as the fronts or the center channel, so I can't imagine that you'd be sending 200W to them.

Jamie - the Onkyo 705 is a seven-channel AVR.

 

[fmw]

Truthfully, such an amp won't ever run at 200 watts. Unless you are hard of hearing you probably won't ever use more than 20 watts per channel on loud peaks if you have a powered subwoofer. Don't worry about the speaker power ratings.

Modern solid state amplifiers don't sound like anything. They amplify the audio they are designed to amplify without distortion or noise. So they all sound the same as long as they are used within their design parameters. Trust me, a 200 wpc amplifier will be used within its design parameters all the time in typical home installation. It is in the pro audio world where this type of rating become meaningful.

The Lexicon is a fine product. The dealer lied to you that it will sound better, however. It was a well meaning lie because he may very well believe it but you shouldn't believe it.

 

[Billy S]

Thanks for the help everyone. So the Onkyo is 100watts per channel, is using a amp going to make a difference in the sound or am I being naive here?

 

[3db]

Can someone please explain something for me concerining amp wattage.

If I buy an amp that is a 5 channel, 200 watt per channel amp (Emotiva xpa 5). And 3 of my speakers are good to 200 watts and my other 2 are good to 150 does it try to push 200 to the 150 watt speakers or does it stop it at 150? Or should I go with a 7 channel, 125 watts per channel. I don't even know if I'm making any sense here, but was trying to find some answers.

A guy at a local shop here was trying to sell me a lexicon ( if that's even the right name) and said it would make a world of difference in how my system sounded.

Here's what I've got.

Onkyo 705
Infinity beta 40's
Infinity beta 360 center
and Infinity beta es250 dipoles.
I've also got 2 Infinity beta 20 bookshelfs for speakers in my zone 2 on my receiver.

Can anyone help me here....

Thanks

For the infinity speakers you are looking at, the Onkyo will be just fine. Like the previous posters have stated before, you won;t even come close to using this much power. There are times when a more powerful amp is needed such as driving inefficient low impedance speakers in a large room.

The power ratings of the speaker are different from an amp. The ratings for a speaker indicate how much power they can absorb without damage. The hidden implied message with that spec is that you don't need to drive them to these levels of power to achieve loud volume levels in your room.

Hope this helps.

 

[fmw]

Thanks for the help everyone. So the Onkyo is 100watts per channel, is using a amp going to make a difference in the sound or am I being naive here?

Very unlikely that it would make any difference. The bass takes most of the power. If you have a powered sub, you don't need much to drive the rest of the speakers. The 20 watt figure I provided above isn't an estimate. It is the actual amount of wattage measured on my right front speaker during loud peaks such as explosions in movies. 100 watts per channel would be overkill in my own system. I have 170 watts per channel but that's just because the receiver I like has that kind of power. I don't come anywhere near using it.

The only thing I will provide you with is the impedance issue. The lower the impedance, the higher the current draw on the amplifier. So if you use low impedance speakers, it is possible that you could exceed the power supply's ability to provide enough current and you could encounter some clipping. This is actually pretty rare in home audio but it is possible. If you have normal speakers, a powered sub and have everything installed in a normal domestic room, it is almost impossible to drain an amplifier of its current delivery capacity. But it is possible in extreme conditions such as very low impedance.

If you don't have a powered sub then you can use quite a bit more amplifier power to drive the bass frequencies on your main speakers. But this would be intermittent power, certainly not continuous.

So the issues relate only to power delivery, not to some magical "sound quality" that audiophiles like to talk about. As I said, it is very unlikely that adding an external amplifier will improve anything. The huge majority of external power amplifiers in home theater applications provide only pride of ownership, not improved performance.

 

[Billy S]

Very cool, I think I understand now. Yes, the sub is a Onkyo 12" 500 watt powered sub, so I wasn't going to be using the amp for the sub. Thanks a bunch for helping the newbie here, it's greatly appreciated, now I can use that money for some other part of the basement.

Thanks again,

Billy

 

[Joe Schmoe]

The Lexicon is a fine product. The dealer lied to you that it will sound better, however. It was a well meaning lie because he may very well believe it but you shouldn't believe it.

+1
(That was all I wanted to write, but stupid forum rules require me to write more. Gee, I wonder if I have written enough now. I would sure hate to use too few words.)

 

[Midcow2]

Wattage

Also remember power is logrithmic.

Sound is normally measured in deciblels= dB

whisper = 30 dB
normal voice = 60-70db
level at which substained exposure may result in hearing loss = 90-95dB
very loud rock concert 115dB
loudest sound possible - 194 dB

Decibels express a power ratio, not an amount. They tell how many times more (positive dB) or less (negative dB) but not how much in absolute terms. Decibels are logarithmic, not linear. For example, 20 dB is not twice the power ratio of 10 dB.
The defining equation for decibels is


A = 10*log10(P2/P1) (dB)

Commonly used dB values
dB level powerratio dB level voltage ratio
−30 dB 1/1000 = 0.001 −30 dB = 0.03162
−20 dB 1/100 = 0.01 −20 dB = 0.1
−10 dB 1/10 = 0.1 −10 dB = 0.3162
−3 dB 1/2 = 0.5 (approx.) −3 dB = 0.7071
3 dB 2 (approx.) 3 dB = 1.414
10 dB 10 10 dB = 3.162
20 dB 100 20 dB = 10
30 dB 1000 30 dB = 31.62


You AVR Onkyo is very nice receiver at 100watts per channel and your speakers are 8 ohm and 91 dB sensitivity ( a little better than average) you should be able to drive your speakers to a very nice level, probably a lot louder than you want

 

[fmw]

So logarithmic, in fact, that a doubling of amplifier power is required for each 3db of additional volume. Some one said your speakers have a 91db efficiency rating. That means that they will produce 91 db of sound pressure at a 1 meter listening distance with 1 watt of amplifier power. You would need 2 watts to get 94 db, 4 watts to get 97db etc.

 

[Billy S]

I was more concerened with the actual quality of the sound from the speakers rather than loudness. The guy told me that if I were to add an amp I would get "cleaner" power going to the speakers which would in return make the sound "cleaner" I'm just glad I can get an honest answer by asking my questions here.

 

[jamie2112]

The guy is trying to make a sale. You have plenty of power for your speakers. Too many of the sales people out there just want to make a sale and don't really care to listen to what the buyer wants. I have seen this firsthand on a few occasions myself. Cleaner sound warrents more power but you have plenty at 100 watts a channel......Do your speakers sound good to you? Thats all that matters.......

 

[rnatalli]

I agree with everyone. If your speakers are 91db efficient and you're using a powered subwoofer, you shouldn't need anything more than what the receiver offers in terms of power.

 

[fmw]

I was more concerened with the actual quality of the sound from the speakers rather than loudness. The guy told me that if I were to add an amp I would get "cleaner" power going to the speakers which would in return make the sound "cleaner" I'm just glad I can get an honest answer by asking my questions here.

Nope. He may well believe it - a lot of people do - but it isn't true.

 

[mtrycrafts]

... Unless you are hard of hearing you probably won't ever use more than 20 watts per channel on loud peaks if you have a powered subwoofer. ....

Heaven help his family and neighbors if he is