How many w.p.c. do I really need?

[MaestroHC]

I recently purchased an Onkyo TX-SR501 receiver. It has 65 w.p.c.x6. I have not set it up yet. A music person told me that I really need "at least 100 w.p.c. in order to do the jazz and classical music justice". He told me that the cymbal crashes,strings, piano, and voices would not be "as detailed" with the 65 watts. I have Canton Nestor 403 speakers. What are your feelings and experiences with this? I appreciate any help.

 

[markw]

I think you should set it up and listen for yourself before getting in yourself all worked up because of someone else's opion who does not have your ears, your room, your tastes or your system.

FWIW, for a BARELY AUDIABLE 3 decible increase of reserve power, you will need to double that 65 watts to 130 and, even then, it won't be all that much louder.

 

[MaestroHC]

MarkW,
Thanks for the info. I'm trying to avoid opening the box so I can return it if necessary. I'm trying to get an answer to sound purity with a higher wattage receiver vs. a lower wattage receiver. If a higher wattage receiver delivers sound realism and purity better, I will return the 501 for a higher wattage receiver. Volume doesn't matter to me; music instrument purity and realism does.

 

[markw]

Important question here.

What receiver does he suggest replacing it with?

There's a very good reasom I ask this which will become apparant in the near future. There are some receivers which, although rated at lower power than some others rated at higher power, produce more real world listenng lpeasure than some units rated at higher power.

 

[MaestroHC]

Mark,
He suggested the Sherwood RD-8108 (100 wpc x 6).

 

[annunaki]

How are you listening to music? Are you listening using two channels, or more? What volume levels do you listen at? What numer of the maximum available on the volume control do you find yourself listening? What is the power handling capability of your speakers? These questions should be answered before you decide what is, "too little wattage" and what isn't.

 

[Yamahaluver]

http://www.myhometheater.homestead.com/splcalculator.html

Go and check this out and will give you a very accurate calculation of the watts you require provided you fill in the data right.

 

[Rip Van Woofer]

..."at least 100 w.p.c. in order to do the jazz and classical music justice". He told me that the cymbal crashes,strings, piano, and voices would not be "as detailed" with the 65 watts.

Crap, crap, and crap. Those mid to high frequency sounds aren't what require a lot of power. It's the loud bass that needs the wattage. What will affect the high frequencies is if the amp is driven to clipping by loud bass. That's IF. What you will hear then is a quite audible harshness, not a lack of "detail". Bear in mind that the tweeters used even in very expensive speakers have power handling cababilities of around 25 watts RMS.

Mark W is right. For that matter, so is everyone else in this thread, so a lot of what I have to say is merely to reinforce or expand on the above. Even doubling the power to 130 WPC only gets you a 3dB increase in sound which is audible, but only just. Moral: if your amp is breathing hard you probably need to quadruple (or more!) the power. And I don't know of too many people who REALLY need 260 wpc!

Unless you have a quite large room, very inefficient speakers, or habitually listen at earbleed levels (because your hearing is already shot!) don't sweat it. I recall hearing about a "rule of thumb" to tell if your amps are adequate: if you have to routinely turn the volume control knob much above the halfway mark in normal listening you're cutting it close. Can't vouch for the truth of it but it seems to make sense. Unless, of course, you have one of those Spinal Tap amps that goes up to 11.

Anecdotally, I have also heard that often one does not feel the need to turn the volume up as much for multichannel listening as for 2 channel stereo because the surround seems to add so much more "you are there" presence that many folks are satisfied at lower actual SPLs. YMMV, of course.

I should also point out that I happily owned and listened to a 60 wpc amp (stereo) for many years in a variety of dwellings and rooms with pretty inefficient speakers.

My bottom line: stick with your Onkyo. If you find you are lacking power, drive the front L and R speakers with an outboard power amp via the preouts (if it has them - not an Onkyo expert here!). If budget is a concern, nice power amps with gobs of power can be found used. And these days it's a buyer's market, according to a friend who is having trouble selling a high-end Plinius integrated!

 

[djoxygen]

Another thing to consider is what load the amp is rated for, and what load your speakers are putting on the amp.

If the amp is rated for 65 W.p.c. @ 4 Ohms, but you have 8 Ohm speakers, you may not be happy with the sound. Plus, if your amp is under-powered for the speakers, you may damage the speakers by over-driving the amp.

Conversely, if the Onkyo is rated @ 8 Ohms, but the speakers are 4 Ohm loads, you're getting the equivalent of 130 W.p.c. and now you've got to be sure your speakers can handle the power.

You're far better off worrying about matching power and load ratings from amp to speaker than fretting about peak power output.

 

[dsa220]

If you follow the traditional rules of HT, (speakers set to ‘small’ with a sub-woofer) then the power should not be that much of an issue unless you plan on letting your neighbors listen in as well. If you listen to a lot of 2-channel and find you need extra power because you want to use the front speakers as large, then you can always get a good 2-channel amplifier to drive the front speakers.

In my case, I am using a separate 5-channel amplifier in my HT system, and it is rated and ‘only’ 85 watts per channel and I listen to a lot of Jazz and Classical music and have yet to find a reason for a larger amplifier (and I run all my speakers [except center] as large). Provided the power supply in the amplifier is of sufficient quality and they provided enough breathing room for the power transistors in the amplifier section, you should be fine.

Plug it in and put on a favorite piece of music. Numbers are only going to tell you so much about a piece of equipment; eventually have to listen to it and see if it fits your needs both ergonomically as well as functionally.

 

[annunaki]

Another thing to consider is what load the amp is rated for, and what load your speakers are putting on the amp.

If the amp is rated for 65 W.p.c. @ 4 Ohms, but you have 8 Ohm speakers, you may not be happy with the sound. Plus, if your amp is under-powered for the speakers, you may damage the speakers by over-driving the amp.

That is only true if, when the amplifier goes into clipping, it exceeds the spearker's continuous power handling capabilities.

Conversely, if the Onkyo is rated @ 8 Ohms, but the speakers are 4 Ohm loads, you're getting the equivalent of 130 W.p.c. and now you've got to be sure your speakers can handle the power.

You're far better off worrying about matching power and load ratings from amp to speaker than fretting about peak power output.

A well made amplifier will typically double it's output power when the load is halfed. Unfortunately, manufacturers of receivers have found ways to cut some corners in the power supply section by using what, in laymans terms, amounts to an impedence matcher in the amplifier. So rather than the amplifier producing more power into the lower load, it does fractionally more, maybe 10 watts or so, or the same as the higher load. And yes, peak power output ratings are utterly useless.

 

[zipper]

I had a Yamaha Rx-V620 receiver(5X100wpc) & it was ok.I would have kept it but I wanted the flexibility of having pre-outs,so I ended up buying a Rx-V3300(6X130wpc) mostly because I got a great deal on it($600).The 1st thing I noticed was the improved quality of sound coming from the same speakers I had.More bass,clarity,separation at average or below volumes.And the ability to play the music at louder volumes with much less degradation of the sound.Looking closer at the unit,I noticed that the power supply was about 3 times the size of the one in the 620,even though it was only rated at 30wpc more with an additional channel(which I don't use).It obviously supplies more current than the 620 did.
I don't think you'll see it in many receivers but it is possible to get all you want out of 65 wpc if the unit has a healthy power supply.Weight of the unit is a good indicator.For instance,the 620 weighed,I believe,22 lbs while the 3300 weighs 48 lbs. On the other hand,years ago I had a Sony 2-ch receiver that was supposedly 100wpc but it was a piece of junk.If I had to guess I would say it weighed about 10 lbs.
I don't know anything about the receiver you just got or the speakers you have,so I would heed the suggestions of the others & try it out.Who knows? It might be a great fit.

 

[Rip Van Woofer]

A well made amplifier will typically double it's output power when the load is halfed.

That's too broad a generalization, IMO. Actually, there are very few amps that truly double their power as the load is halved. The majority of well-regarded and well designed amps in both consumer and pro audio, at price levels from middling to high-end, claim "only" a large fractional increase in power as the load is halved.

The reasons for this are beyond my understanding but I gather there is more to it than a big honkin' power supply, and that it is fairly costly and difficult to attain the goal of power increase that is in direct proportion to load. Remember, the lower the impedance the closer you are to a short circuit. If I may be forgiven gross anthropomorphism, amps and other circuits get increasingly nervous as the load impedance decreases. That is how I understand it at my trained-chimp-level electronics.

In fact, the Carver-designed Sunfire power amps and some others reputedly manage the trick without using a big hunk of ferrite and wire (in contrast to Krell, whose amps come with a coupon for hernia surgery...kidding!) via clever and somewhat unconventional engineering; there is more than one way to skin this particular cat but again, it ain't easy or cheap.

No doubt our Fearless Leaders and/or Dan Banquer can enlighten us further!

 

[djoxygen]

That is only true if, when the amplifier goes into clipping, it exceeds the spearker's continuous power handling capabilities.

Not necessarily. A solid state amp driven into clipping will essentially try to turn sine waves into square waves, but not good, clean ones. Looking at an oscilliscope on the amp output, the leading and trailing edges of that square wave can have really nasty spikes that a FFT will reveal as extremely high frequencies that can exceed the speakers' physical limits even though the RMS power ouput can still be within rated tolerance.

This will not be the case in every pairing of amp and speaker, but it is a possibility, and a potentially catastrophic one (at least for the speaker cone).

 

[annunaki]

Rip,

I was making a generalization. A really well made amplifier (I am not really talking receivers here) will double or get close to doubling (80%) output power as the load is halved depending upon design. With the current amplifiers that do not increase power as the impedence drops, they most likely employ a circuit which allows the same power output over a variety of loads. I would assume most are set up to deliver the same amount of output between 4 and 8 ohms. Basically it is a regulated output stage. The power supply components can only deliver/handle so much current into a predetermined load and to prevent doing more, the output is regulated between the desired impedence. Basically the amplifier is set up to deliver the power at say 4 ohms, then an impedence matching type circuit is employed so that the power output stays the same at a higher resistance load. I could be wrong though.

Car audio amplifiers are actually a good example here. Most car amps, whether class A/B, class D, or Full range class D, will double their output power as the load is halved or be within 80% (of doubling) until you reach their specified low impedence limit of the design. Some amplifiers are so well made and so powerful that (and I have seen this) the speaker leads, under full output were shorted together and could actually be used as a primitive arc welder!

 

[Rip Van Woofer]

Thanks Annunaki, always enjoy learning something! True, a lot of good amps do indeed manage around an 80% increase as the load halves to 4 ohms - no argument there! - thanks for explaining the hows and whys clearly.

BTW, I've always wanted to try my hand at welding. Can you suggest a good car amp?

To DJ Oxygen et al: there's a (most likely) good if lengthy article about clipping and why it makes tweeters blow (it's actually called something like "Why Do Tweeters Really Blow?") on the Elliot Sound site. I haven't read it but it's there for those who are interested. (I'm merely content to know that clipping=BAD!)

 

[djoxygen]

http://sound.westhost.com/tweeters.htm If anyone else wants to read it. Good article, good math, and good diagrams!

It doesn't really address the underpowered amp question directly, but as RvW says, clipping is bad whether it's your amp doing the clipping or your speakers.

I may have been misdirected years ago on the direct chain of events and causality, but the math and my experience do both lead to the following:

A driver can better handle some amount of clean (and transient) input past its own rated tolerance than it can solid state clipping and excess current generated by an over-driven amp.

 

[annunaki]

djoxygen,

You are correct that odd order information does have the ability to damage speakers, but that only happens because the odd-order spike, as you put it, has most likely exceeded the speakers powerhandling limits causing the driver to move past its mechanical limits. Tweeters are much more prone to this type of damage than woofers as there is so little coil/former in the gap to begin with. They also lack sufficent movement for coooling when being pushed near the limit. The amplifier also does not try to turn the sine wave to a square wave, it simply cannot produce any more output so the wave flattens (clips) for the duration of the wave once the signal at that frequency diminishes it goes away.

 

[djoxygen]

The amplifier also does not try to turn the sine wave to a square wave, it simply cannot produce any more output so the wave flattens (clips) for the duration of the wave

"Try" was anthropomorphic of me. I usually refer to my gear as "he" and "she" depending on how temperamental a particular piece is at the time. >:-D

 

[mtrycrafts]

I recently purchased an Onkyo TX-SR501 receiver. It has 65 w.p.c.x6. I have not set it up yet. A music person told me that I really need "at least 100 w.p.c. in order to do the jazz and classical music justice". He told me that the cymbal crashes,strings, piano, and voices would not be "as detailed" with the 65 watts. I have Canton Nestor 403 speakers. What are your feelings and experiences with this? I appreciate any help.

You received a lot of good info here. Why would I expect anythiong less

Doubling the amp as was mentione ads 3 dBs but that occurs at the peaks when you listen at very loud levels, maybe. And, your speakers may be groaning by then as well as not many speakers reproduce clean sound at high levels One only has to read some technically good reviews of speakers

So, enjoy what you have and stop worrying, or you will see gremlins, or in this case perceive them at every corner, so to speak