# How much does the Watts matter?



## goodears (Jan 2, 2013)

Is the Watts super important in a Receiver? I read someone say it isn't as important in speakers and it was a marketing thing. What about receivers? If it does what is a good "amount" of watts? Thanks.


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## tonyvdb (Sep 5, 2007)

There is a much bigger picture that needs to be looked at.
First what speakers you are going to be using and how efficient they are.
Second, what size is the power supply in the receiver,
Third, what are the actual bench test results all channels driven of the receiver?

Many receivers say that they can do 120 watts per channel but what they dont tell you is that the test they do to determine this is flawed. They use a 1kHz test tone to get the results not full frequency. most receivers fall well short of the specifications they advertize. Usually about 25% less output all channels driven than what they say.


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## lcaillo (May 2, 2006)

The context of the comparison is important. Watt ratings are not the whole story. It is difficult to answer the question without more information about what you are comparing. The difference between 80 and 100 watts in similar designed AVRs would not be significant in itself in most cases, but the difference between 60 and 150 watts probably would be. Between brands, some 80 watt receivers with more power supply capacity could be better than other 100 watt units with limited power supplies and limited current capacity. If you are driving extremely efficient 8 ohm speakers, that same difference might not be meaningful.


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## 8086 (Aug 4, 2009)

Wattage really depends on the speakers you run, the size of the room you have, and how much current you can draw from a wall. With the right speakers in a average sized living room, a 30 or 40 watt amp, may be all that you need. But keep in mind, you can always _blow_ a set of speakers by under-powering them, conversely you can _burn_ out a set of speakers (voice coil) by sending them too much power. Generally, you want to run an amp at no more than 50-60% of its rated power. Any % higher and the amplifier enters its early phases of clipping, sending square waves through your speakers which results in a blown woofer or tweeter due to a lack of clean power.

Tony said it best:



> First what speakers you are going to be using and how efficient they are.


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## robbo266317 (Sep 22, 2008)

Do you have a specific receiver or two that you are looking into, and what speakers are going to be used with them?

For most home setups a receiver in the 80 - 100 Watt RMS should be adequate. (If it is indeed true RMS as mentioned earlier)
The other area that is often neglected is the fact that transients can exceed 10dB above the average listening level. So if you typically listen at 10 Watts then the transients can be 100 Watts. If you listen at a higher level you will be clipping the transients.

Again, it depends on the individual speakers/receivers involved.


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## AudiocRaver (Jun 6, 2012)

Indeed. Here is one way to approach it: Start with speaker efficiency, add for the room, add for desired listening level, then add for headroom.

Say speaker efficiency is 87 dB with 1 W RMS at 1 m. For home theater seating at 2 m (distance x 2) add 3 dB (3 dB for each doubling of distance in a fairly dead room). For a strong listening level of 90 dB during loud passages, add 3 dB. For decent headroom (instantaneous peaks), add 12 DB. It adds up to 18 dB, round up to 20 dB for easy math, that is 100 X 1 W (every 10 dB is 10 X the power), or 100 W available amplifier power needed.


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## AudiocRaver (Jun 6, 2012)

Beg pardon, my two-channel view the world gets in the way again. Allow me to revise this example in Dolby reference level terms:

Start with speaker efficiency, add for Dolby reference level, add for headroom, add for personal preference, then add for the room (the order doesn't really matter).


Say speaker efficiency is 87 dB with 1 W RMS at 1 m.
For Dolby reference level (85dB), subtract 2 dB.
For headroom (highest instantaneous peaks), the Dolby standard says add 20 dB.
Then allow for individual preference, say you like to run your movies loud and calibrate the reference level 3 dB higher at 88 dB, then add 3 dB.
For home theater seating at 2 m (distance x 2) add 3 dB (3 dB for each doubling of distance in a fairly dead room).
This example adds up to 24 dB, (20 dB is x 100, 4 dB is x 2.5, total is x250), or 250 W available amplifier power needed. Without the added 3 dB for extra loudness, the end result would be 21 dB, or 125 W available power needed. In a live room, this could easily come down another 2 or 3 dB (60 to 80 W needed).

Edit: For distance, theoretical 6 dB for doubling of distance, closer to 3 dB in a typical room.


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## tonyvdb (Sep 5, 2007)

And there lies the main issue, most receivers in the sub $1000 range can not output cleanly 60-80watts per channel all channels driven without some distortion. Its been my experience that a receiver that weighs less than 30lbs will fail in this area badly.
I know some people will disagree but Onkyo has been a leader in this regard over and over again bench tests have revealed that they come much closer to their rated outputs because they always put a larger power supply under the hood even the 609 was bench tested to do better then 85watts per ch all channels driven.


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## fschris (Oct 31, 2009)

....you get what you pay for..... but i believe it is like a bell curve.

0-600 not very good ( toyota carolla)
600-1000 better ( Honda)
1000-3500 sweet spot (BMW)
3500-10000 wasting money ( unless your just loaded and dont care) (Bugatti)


so believe what you will in those price ranges on the specs of a receiver. even then your best bet is to read forums and get some hard data to back up your purchase.


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## 8086 (Aug 4, 2009)

fschris said:


> ....you get what you pay for..... but i believe it is like a bell curve.
> 
> 0-600 not very good ( toyota carolla)
> 600-1000 better ( Honda)
> ...



I kind of disagree. I think Emotiva has some amps for under $600. If you look hard enough, you can find _almost_ anything used for under $600.


EDIT: 
I missed the word "receiver". Then, ya: over 6k, you are wasting money. Over $6,000, you'd be better off going the rout of separate amplifier and pre-amplifier/processor. And for the most part, spending more than $15k on separates would be overkill, unless you had some very large demanding speakers that required such superfluous drive electronics (like electrostatic speakers or B&W 800D)


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## lcaillo (May 2, 2006)

fschris said:


> ....you get what you pay for..... but i believe it is like a bell curve.
> 
> 0-600 not very good ( toyota carolla)
> 600-1000 better ( Honda)
> ...


There are lots of decent products for under $600. They may not be as powerful as more expensive units nor have the current capacity in the power supply, but this price is not such a big limitation. 

I do not agree that price is correlated to performance, necessarily. As noted above, there are also lots of good used products out there. You get what you pay for if you do your homework and get lucky. Only one of those do we have control over.

A Corolla, btw, is an exceptional vehicle. An extremely reliable car that does what it is designed to do quite well. I owned two of them and put almost 600K miles on them combined before I sold them, for less than $600 each.


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## fschris (Oct 31, 2009)

8086 said:


> I kind of disagree. I think Emotiva has some amps for under $600. If you look hard enough, you can find _almost_ anything used for under $600.
> 
> 
> EDIT:
> I missed the word "receiver". Then, ya: over 6k, you are wasting money. Over $6,000, you'd be better off going the rout of separate amplifier and pre-amplifier/processor. And for the most part, spending more than $15k on separates would be overkill, unless you had some very large demanding speakers that required such superfluous drive electronics (like electrostatic speakers or B&W 800D)



exactly Emotiva ROCKS!! i was just generalizing receivers. although like some also said; give the receiver a weight test. if its under 35 pounds it has a weak power supply system.


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## fschris (Oct 31, 2009)

lcaillo said:


> A Corolla, btw, is an exceptional vehicle. An extremely reliable car that does what it is designed to do quite well.h.


this is the epic struggles i have with my wife ... she is practical. i am not! it helps balance me out.

do I need 2 subs in the living room. of course not!


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## 8086 (Aug 4, 2009)

lcaillo said:


> There are lots of decent products for under $600. They may not be as powerful as more expensive units nor have the current capacity in the power supply, but this price is not such a big limitation.
> 
> I do not agree that price is correlated to performance, necessarily. As noted above, there are also lots of good used products out there. You get what you pay for if you do your homework and get lucky. Only one of those do we have control over.
> 
> A Corolla, btw, is an exceptional vehicle. An extremely reliable car that does what it is designed to do quite well. I owned two of them and put almost 600K miles on them combined before I sold them, for less than $600 each.


fftopic2:

Agree, the Corolla is the AK-47 of cars. But when it comes down to performance which I think is where Caillo was taking this, A Corolla doesn't drive quite like the New Scion FR-S (Toyota GT-86, UK-EU) or Subaru BR-Z or Porsche Boxster or a BMW 3-Series (335is:clap . Most Harman-Kardon products could be Likened to the FR-S, low on power (Ratings) and high on performance potential as well as being sold at a price that most people can afford.


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## bmdtech (Dec 17, 2011)

fschris said:


> this is the epic struggles i have with my wife ... she is practical. i am not! it helps balance me out.
> 
> do I need 2 subs in the living room. of course not!


Of course not, you need 3~


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## 8086 (Aug 4, 2009)

bmdtech said:


> Of course not, you need 3~


http://www.audioholics.com/tweaks/get-good-bass/two-subs
http://www.youtube.com/watch?feature=player_embedded&v=ayOXz26qm3I


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## JerryLove (Dec 5, 2009)

No. You can't tell just my wattage. There's the ability to deliver current as resistance changes to worry about.
Also, though [email protected] tells you power consumption, it may not be at the same ohm rating that your amp is judged by.

An ideal amp (let's say a Krell KSA-150) puts out (nominally) 150wpc @8ohm. @4ohm, however, it puts out 300wpc. That amp is actually rated to 1 ohm at which it puts out 1200wpc. Can you imagine the current requirement?

OTOH: As impedance rises; the ability to maintain voltage can be an issue. Tube amps actually start to carry an advantage when we discuss 16ohm speakers and the like.

Seriously though: If the difference in amp power between AVR#1 and AVR#2 is something you are even worried about; then you should be using a separate amp. $285 gets you a Peavey amp that does 300/530/900 x2 watts at 8/4/2 ohms. $800 will get you one 4x that powerful.
If that's still not enough, you can buy 2, run them in bridge mode, and get 7500wpc into 2ohm. (together they will cost $1600 and weigh 14lbs)


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