Axiom Home Page Forums General Discussion Technical Questions Amps and Power, for Micah

Hi Micah. Here is the explanation I got when I asked one of the lead engineers at Peavey about what some of the ratings on one of their new amps meant.

Keep in mind that pro amps are usually driven harder than consumer equipment.
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Hi Fred

Normal use is 1/8 power. That means uncompressed music up to but not exceeding clip. Clipping will compress the material. Safety agency requirements are that the amplifier does not thermal at 1/8 power while at 10% high line (132VAC) at the minimum rated impedance. The 1/8 power is based on what the manufacturer rates the amp for, or whatever UL measures, whichever is higher. Their concern is that there is no nuisance tripping to encourage a consumer to go into the amp and defeat the thermal protection.

The current draw figures in the spec sheet represent current consumption at normal (1/8) and severe (1/3) duty cycles. The consumption is stated for the three rated load impedances.

Hope that helps

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The question came about when he talked about UL tests where they are required to draw maximum rated power for x seconds before they trip the protection circuitry.

Here is the thread the post came from. If you want to learn a little more about amps and amp design, its a great thread to read. It does have the obligatory multiple pages of troll posts that show up in most interesting threads at avs, but its worth wading through those for the info the thread contains.

Oh yeah. On RMS power, I think this is more a marketing invention than anything else. Amp ratings in the car audio world are not subjected to the same level of regulation as consumer audio.

No doubt Johnk will be along shortly to correct my on my mistakes.

Wow, so an amp rated at 1000 RMS could only put out roughly 130 watts of continuous power? There certainly are some dubious marketing techniques in use if that's the case. In all the research I have done (and one of my favorite hobbies since I was a teenager has been car/home audio, so I have done quite a bit of looking up on the subject) the RMS rating was how much power an amp could continuously produce. Most car audio amps would list two ratings, their RMS rating for example might be 500 watts, and their peak power rating might be 1000 watts or more, but it was understood those peak bursts were short lived, perhaps a second or two at the longest.

That was why we bought and installed capasitors... Which were basically batteries that were kept charged in reserve to help boost musical peaks that an amp might not be able to reach, or run out of power while trying to do so.

I greatly appreciate your continued efforts to help clear up some of these misunderstandings. I know there are many people out there that have those same beliefs I had before coming on here. And we still continue to see people with that mind set come on here and get their opinions corrected by those who know more about the way things have evolved. There are certainly many ignorances about these things floating around out there. As it seems that has a lot to do with questionable information given out by the majority of car audio companies.

My intentions are not to prove that those people who still believe in the age old theory of 'sealed = clean, ported = louder' are right. I'm only attempting to explain why they believe that. I know it took me a long time to come around to even believe what was being said on here because after havng built dozens of sub box's for my own cars as well as my friends, I was pretty sure I knew what I was talking about. It wasn't a 'myth' that sealed box's sounded cleaner, the sealed box's we put together did sound cleaner because the ported box's we made were far from perfectly engineered. They put out loads and loads of bass, but that bass wasn't so intelligable as it was just simply... LOUD!!!

I only hope that understanding where all of these myths got their roots can help the members of this board understand why so many people come on here with those beliefs firmly embedded into their brains. Simply telling them they don't know what they're talking about probably won't change their minds if they have a similar background as I have.

We just have to make it clear that the world of home audio is on an entirely different level. The difference is night and day really, looking back on the subwoofers we put in our cars back then, they were VERY crude! Nothing even close to what is available these days for your living room. There is very little comparison between the two worlds (a 1980's trunk subwoofer vs an EP800), besides them both being instruments that are here to serve in satisfying our cravings for bass.

Car audio amps are also rated with much more THD, many with as much as 10%, take that same amp and try to get the RMS at 1% or less and it most likely falls well short of most of the avr's we mention here.

I'm still hopping that Johnk will drop by and correct anything I got wrong. My understanding of amps and power is far from solid.

Having spent a little time on a car audio forum recently trying to figure out what to do about the not so good sound in my car, I get the impression that car audio has stepped out if its 'loud and proud' roots to at least partially embrace sound quality.

The spl folks seem to understand what they are doing does not involve sound quality. I also understand there is a sound quality category at competitions now.

Actually there has always been two camps in car audio. Way back in 1991 when I went to the IASCA Championships they had both 'SQ' (sound quality) and 'SPL' (sound pressure) catagories. While we didn't know exactly what we were doing, some of us really did try to make our rides sound as good as we possibly could. While most of my friends were out spending $80 bucks on a 1000 watt Pyramid amplifier that sounded like crap, I invested hundreds of dollars in Precision Power amps (PPI) that were rated at 4 x 50 watts at .002 THD.

Sure I had friends that you could hear 10 blocks down the road, but you didn't want to actually be in their car. My car on the other hand may not have shaken the neighbors windows when I drove by, but those sweet MB Quart's sounded like heaven (at least to me), and were plenty loud from where I sat.

exactly

Yea.

Mm.

Yahtzee!!

Look Everyone! It's Sean!!!

::applause::

Where?

*looks around*

back in my car audio days, i used phoenix gold amps, and Dynaudio mid's and highs, with Boston Acustic pro subs.. i was in the SQ crowd... and the phoenix gold amps had very true ratings.. but you paid for that......


with amps today, there are so many technologies that companies are using, analog, digital, and a combination of both...

the best way for someone to understand how an amp works is to learn how a class A amp works, when you understand how a class A amp works then you have a firm basic knowledge...

http://sound.westhost.com/class-a.htm

in the home theater area, one of the biggest things to look at is the rating of the power supply, and the filter capacitors..

one example i am using is one of the amps that i have.
a Krell kav 250a

50,000 microfarads= uF of filter capacitance, a power transformer of 2kVA= (kilovolt amperes) rating


now for a yamaha RX-Z7 7.1 channel receiver.


(large E-core and 2 x 18,000uF= microfarads 71V capacitors)

i could not find the rating for the transformer..... but the krell amp is a 2 channel amp, where the yamaha has a 7 channel amp... and from the pictures the transformer in the yamaha can not even compare to the krell..



one reason the capacitors are important, the capacitors oppose a change in voltage, while a transformer opposes a change in current, as well as being able to change the voltage either up or down. depending on how you wire the capacitors and transformer in a perfect world neither the voltage or current will change... you have to keep in mind this is the power supply section of the amp... the is before your music is introduced into the circuitry...



this is a Krell amp, you can see the the majority of the amp is the power transformer, and at the top of the picture you can just barley see the blue capacitors. This is an older amp, but the electrical principles are the same no matter how old the electronics are.

this is one of the reasons that the pre-pro route is ideal solution, if money is not a huge deal.

No, Micah; an amp rated at 1000 watts per channel has to output that full 1000 watts continuously for at least five minutes with the number of channels required(at least two)being simultaneously driven. That's the test required by FTC regulations for all amps sold in the U.S.(and effectively, Canada as well). The 1/8th power test, which I've mentioned here several times in the past few years, is a different UL(Underwriters Laboratory)test for fire safety, which the unit has to survive without overheating. 1/8th isn't just something picked at random, it's been found to be a rough average of the power that's used in playing a typical music CD. That is, sometimes less than 1% of full power is used during the playing, at other times 100% might have to used, but the average over the 60-80 minutes would be about 12% of the full power rating.

This 1/8th power number is also typically the number used(unless specific language such as "full power" is used)when the manufacturer quotes a power consumption figure and puts it on the back of the unit. This misleads those who think it's consumption(including the dummies on the first page of the AVS thread Fred linked)at full power into thinking that the manufacturer is lying, since the consumption number shown is less than the full power output claim, and obviously amps work at less than 100% efficiency. As I've described before, the idea is that at 1/8th power class AB amplifiers are about 20% efficient(class D is somewhat higher), so a "7X100 watt" unit running at 1/8th of full power would be putting out about 90 watts total and would require about 450 watts input to do that. So 450 watts power consumption gets put on the back of the unit and the uninformed laugh/scream because obviously 700 total watts can't be output with 450 watts input when efficiency is well under 100%.

Fred, I got so disgusted with the silly talk on the first page of the AVS thread that I stopped reading. However, if you say that someone from Peavey later brings in factual information, I'll read the rest. Fortunately I read very quickly; I took one of them speed reading courses and was able to read War and Peace in 50 minutes(it had to do with Russia).

One point that I can add at this time is that the term "RMS" power or watts shouldn't be used, because there is no such thing(despite frequent use, sometimes even by manufacturers). Voltage continuously varies from about +170 to -170(in North America)and a special type of average called root mean square is used(comes out 120 volts)to show the effective overall voltage. This is used when it meets something(like a speaker voice coil) that has a resistance and results in power being used. A watt itself is a fixed amount of power and doesn't vary, so no RMS or other average is needed to express it.

John. The gentleman from Peavey goes by the handle of sickneedshelp and represents himself as one of the senior engineering staff at Peavey.

I usually pick up on technical stuff pretty quickly, but continue to struggle with all things relating to electricity.

Start at the beginning Fred (molecular level) and it'll become clearer. Also, don't believe the bullshit and stick to theory and math.

John - you're my hero.

Michael, i don't think we need to introduce hole flow into this conversation.....

But, I've been anxiously waiting.

cat, im not going to go into any further depth than my original statement on hole flow... ill let google teach you guys about hole flow if you want... but im not touching that one, without any formal education on electrical principles there would be no reason to understand it.

Quantum mechanics? That put me to sleep a couple decades ago.. You just carry one with that one. You an EE? My background is in power generation and reactor operation. Wish I would have followed through with some college, but met a girl and got distracted……. Story of my life.

Man, I wish I had girls as an excuse for my limited usefulness.

Michael, sounds like we went to the same school.... i was an Electrican on a sub out of pearl... If everyone here went to efunds no one would have questions....

finishing up my degree now, in Economics... a buddy from my division is getting his EE.....

As always, great info John. I never mean to doubt you, as you are a much more knowledgable man than I in this (and likely most other) area. It's just so hard to swallow some of this stuff when I've lived with what I thought was gospel for the last few decades. It's like walking into a church, burning the bible and exclaiming, "this is a lie".... WHAT, THERE'S NO SUCH THING AS RMS???

But after looking into it I see what you mean. RMS is based on an average of a power wave, not a constant figure. Still, it seems to be pretty widely used not only in car audio, but all audio as far as I could tell. I did stumble upon some rather humorous things while looking these things up. This one in particular was enlightning...

Clicky

Also, as long as it's all correct, Wikipedia had a lot of good info...

Wiki-clicky

I was expecially intrigued by this statement in the 'Power and Loudness in the Real World' section...

" The sensitivity of loudspeakers, rather than merely the often-quoted power-handling capacity, is important. Many high quality domestic speakers have a sensitivity of 84 dB for 1 W at 1 meter, but professional speakers can have a figure of 90 dB for 1 W or even 100 dB (especially for some large-coned woofers). I.E., An '84 dB' source "speaker" would require a 400-watt amplifier (assuming it didn't burn out) to produce the same audio energy as a '90 dB' source being driven by a 100-watt amplifier, or a '100 dB' source being driven by a 9.92 watt amplifier(though in practice modern sub-woofers are often driven by high power amps to overcome the restriction of a small enclosure through the use of equalization). This does not mean a bigger speaker can produce more sound with less overall power. Just that a larger speaker can typically handle more initial power and so requires less amplification to achieve the same high level of output. This means using a speaker with a higher dB rating can be more advantageous as many amplifiers inevitably produce a certain amount of distortion for a given level of amplification. So, (more speaker)+(less amp.)=(same "loudness")+(less distortion)".

It got me to wondering what the M80's sensitivity is. I had thought I'd seen it on here that they were around 87 db's. But looking them up in the products section under specs the only figure I could find was the 'SPL in Room1w/1m(db): 95 dB' and 'SPL Anechoic 1w/1m(db): 91 dB'... is one of these figures the sensitivity rating?

The other interesting thing I got out of it was this...

"The term "Music Power" has been used in relation to both amplifiers and loudspeakers with some validity. When live music is recorded without amplitude compression or limiting, the resulting signal contains brief peaks of very much higher amplitude (20 dB or more) than the mean, and since power is proportional to the square of signal voltage their reproduction would require an amplifier capable of providing brief peaks of power around a hundred times greater than the average level. Thus the ideal 100-watt audio system would need to be capable of handling brief peaks of 10,000 watts in order to avoid clipping (see Programme levels). Most loudspeakers are in fact capable of withstanding peaks of several times their continuous rating (though not a hundred times), since thermal inertia prevents the voice coils from burning out on short bursts. It is therefore acceptable, and desirable, to drive a loudspeaker from a power amplifier with a higher continuous rating several times the steady power that the speaker can withstand, but only if care is taken not to overheat it; this is difficult, especially on modern recordings which tend to be heavily compressed and so can be played at high levels without the obvious distortion that would result from an uncompressed recording when the amplifier started clipping".

It was this that got me thinking the guy who was trying to talk me into a 1000 watt amp to drive my M80's with was trying to account for these 'musical peaks'. If I'm listening to my speakers at a level that pulls around 10 watts of power from my amp normally, it would take 1000 watts of power to cover these peaks. I don't know this was the reasoning behind his advice for a fact, just speculation.

micah, a LOT of the guys that are selling audio or video equipment don't really know THAT much about what they are selling.... how many times have you gone into a store and known more about the product that they are selling than they did.... now i'm not saying every sales guy is incompetent and doesn't know his product... but i would feel safe in saying that most of those guys just don't care enough to learn their product to a level that you or I would hope. this is ESPECIALLY true if you go into best buy, or other similar chain stores.... if you go to the boutique stores those guys are more likely to actually know what they are talking about, but then you get to pay boutique store prices

Most definately. But then again you're not very likely to run into Chris or John working at BestBuy because... well because they're entirely too smart to work at BestBuy.

Micah. Here's another link for you. It deals with pro sound, but is also applicable to home audio. Most of the rock we listen to has on the order of 6db of dynamics. Its not until you get into classical that you see anything approaching 20db of dynamics.

If you are sitting 8-12 feet from your gear listening at reasonable levels, say 80db (pretty loud) you will be using a whole 1 watt for the 80 db content. Add 20db dynamic peaks and you are using a whopping 57 Watts at peak. This is using the M80s at 95db sensitivity.

Note also that when they talk about 20db dynamics I believe that is from the quietest to the loudest passages, so on average, you would need to have power available for maybe half that to avoid clipping. As your listening level goes up, you will need correspondingly more power for dynamic peaks.

Follow the calculator link on the page linked above and play with it for a bit. It will give you a much better idea of how much power you really need.

Micah, the Elliot article is excellent and the Wiki article is generally fine(few quibbles we don't need to get in to). They among other things make the point that there aren't any "RMS" watts, and that RMS is properly applied to voltage and current.

As was said, a watt is a fixed quantity, the standard technical definition being that it's the power resulting from 1 joule of energy being applied for 1 second(that answers everything, doesn't it?). A couple hundred years ago James Watt was comparing the power of his steam engines with rival horses(never had anything to do with electricity), but now his name lives forever in electronics. One fact is that about 746 watts equal 1 horsepower. Now this might not seem to be the most useful piece of information, but if you run into an obnoxious audiophile who's bragging about his new 500 watt amp, after telling him what he can do with his 500 watts(he'll only need 1 most of the time)you can point out that it's only about 2/3rds of a horsepower(weak!).

By the way, did you happen to satisfy yourself about the relatively small effect of a 3dB sound level increase, as was suggested here a couple weeks ago when you questioned it?

And “horse power” is a term that’s nothing more than a descriptor for a mathematical summery of torque over time, much like the term “watt”.

Fred, just to clarify, my M80's sit 16 feet from my seating position. On an average day I would say 80 db's would be about an average of what I play them. When my lady is in the room working with me I turn them down lower. But then there are also times when one of my favorite songs are on, and I really crank them over to 'feel' the bass notes coarse through my bones. This is an addiction I picked up during my car audio years. Having a pair of 12 inch drivers a mere 3 feet from your back being fed by a high watt amplifier that needs only fill a small space produces quite a bit more bass than can be achieved in a 5000 square foot room.

Also, let me make it perfectly clear that I in no way took the gentlemans recommendations for buying 1000 watt mono blocks for each channel serioiusly. I merely wondered why he would have had such an opinion concerning my M80's. I have made speculatory statements in an effort to provide theories as to his reasoning. But those shouldn't be taken as my opinion in the matter. The XPA-3 drives them to levels I already can not tollerate. It was just an interesting comment is all.

John, I satisfy myself on a regular basis... er, oh wait that isn't what you meant is it?

Seriously though, I wish I could find the thread that gave me the opinion that I shared in your link. I'm guessing I understood what was discussed incorrect. It wasn't too long ago, and we were discussing the effects of having to double the wattage to achieve even just a few extra db's of output. After that fact was established I made the comment that if the 300 watts my XPA-3 was providing only produced 3 or 4 more db's of output than the 125 watts my Denon provided, then there was a BIG difference in those 3 or 4 db's. And as I remembered it, I thought you agreed that while 3 db's looks like not much on paper, in the real world a 3 db increase was in fact a substantial amount of volume.

As is seems, I guess I remembered that conversation incorrectly. I apologize for providing misleading information, but it wasn't intentional, I thought that was the verdict we'd come to. So anyway, that takes me back to square one in that area then. As I've discribed before, with the Denon I could only get the volume knob to around 90% max volume before the speakers sounded overloaded. There was obviously a lot of clipping occuring at this level. Once I hooked the M80's up to the Emotiva, taking the volume knob to the same position produced an extrodinary greater amount of volume (levels that I could not tollerate), but at the same time the speakers seemed to handle those levels with ease instead of sonding like they were about to break.

So now I'm left wondering, how could an amp that only produces a little over twice the power make that big of a difference in percieved volume? I know that the Denon had to have been making somewhere between 100 - 120 db's of output because at SRoodes house he was using a Denon similar in power rating as mine, and he showed me on his SPL meeter that we were listening at 100 db's. And we have the same equipment. And I have fully grasped notion that the volume position has nothing to do with how much power is being used between the two amps because of the power curve at play. But the way I understanding it, if my new amp can only add an extra 3 or 4 db's increase in volume, then why is the percieved output so much greater?

Miach...


i just to have 3 JL 10 W6's powered by a 1000w phoenix gold amp.....

i don't think i will EVER own anything that loud again... i think it would take 4 ep600's to get close to how loud that damn car was.....

after that car i went the 2 12's route, and the 12's were much more subdued if you will....


i have been thinking about getting a second EP-600 though.....

We know, we know...

Fred, as we discussed a couple years ago, I don't care for that Crown calculator. If it's used without the correction for the room effect the result comes up about four times too high, and there's no hint of this on the calculator page itself. On the discussion page it doesn't appear until an "Other Considerations" section near the end. Even then, instead of suggesting that the figure from the calculator be divided by four(and a smaller amp be bought), the suggestion is made that it be used for added headroom.

On another point, if a correction for the room contribution(either the one suggested by Crown or another)is applied, then the in-room figure for speaker sensitivity(e.g., 95 dB for the M80s)shouldn't also be used, since this would be counting the room effect twice.

When a peak of as much as 20dB is mentioned, this is almost always referred to the average, rather than the minimum, level. For example, listening at a comfortably loud 80dB average, on some material a peak as high as 100dB might take place. The total dynamic range(quietest part, but not silence, to the loudest part)on a few of my classical CDs is as much as 60dB, which would mean listening over a range from about 40dB(nearly inaudible)to about 100dB. On the other hand, one of the pop recordings used in a speaker stress test described in my AES Journal was so uniformly loud that the total dynamic range was essentially 0dB.

Okay, enough of this miserable typing with the board in this condition.

JL W6 V2's are definately the SHIZNIT!!!

So many of my friends thought they had to have the W7's, but those are just absolute insanity. The W6 V2's are head and shoulders above the W7's IMO.

Ah, so it's not just me eh??? THANK GOD, I've been wondering what the hell was up with my computer for the past two days.

*Hint*

What I've found works is writing something out, then start a sentence a few lines above it and write out the rest of my post from there. Then I simply cut it out and paste it at the end of my post.

P.S. So if any of my posts seem out of order... then I obviously forgot to cut and paste it.

Well, I didn't think I'd mentioned it in a few days, so I wanted to refresh everyone's memory.

Micah, at least at the moment neither of the problems that I mentioned(the jumping and disappearing bottom lines and the big lag in key response)have reappeared.

Mica –

Well…. to understand your perception holistically, the answer to your question is a mutually exclusive dichotomy of emotion and logic. Your perception is a mix of real and non-real and both. Depending on what perception you are referring to, it may just be an emotional response, or it may be very real. If you are referring to dynamic peaks at an already loud SPL, it probably is real. If you’re referring to constantly moderate SPL with little to no dynamic peaks, then it’s probably a perception based on some form of emotional response.

When speaking to the peaks, and why an outboard amp would have “real” gains over an integrated amplifier that is housed in an AVR such as your Denon, there are a couple possibilities that are logically supported. The outboard amp more than likely has a more robust power supply. Just take a look at the PSU in the Krell dakkon posted above. Remember, the power supply is where the amp(s) get their power from. Amps do not generate power; they simply change the amplitude (add gain) of a millivolt signal they receive from the pre-amp, (which in some instances converts a sine wave that represents frequency, into millivolts). The PSU converts power from the electrical wall outlet to usable power for the amps. As the sine wave goes up and down, the power requirements to match it will follow.

Voltage will dip and rise with the sine wave due to an instantaneous flow of electrons being allowed to pass to the speaker drivers, through the coils and back to ground. (think of your thumb holding back a steam of water in a garden hose with each water droplet being an electron under pressure from the water main). The recovery of voltage (pressure) is dependent on the current being supplied by the power supply. The variance of this dip and rise is determined by the potential current supplying capacity of the power supply and what type or level of capacitance it has (think of current as the number of electrons, or water droplets in the garden hose and water main). As you apply gain to the sine wave, the domino effect is more needed electrons at each speaker driver. When the power supplies current supplying potential has been met, clipping occurs. Obviously, when there is a greater supply of available current for the amp sections, clipping will occur later, verses sooner.

Then of course there’s always the individual rating of each component. Without looking real hard at the score card and spec of each, it’s hard to determine exactly how much “real” power each amp can supply. A rating of 100 WPC is completely meaningless without supporting measurements.

I’m obviously not an expert of amp design, electrical theory, or philosophy, but a student of all. In other words, I don’t fully appreciate what I don’t know that I don’t know. However, I do know I don’t know shit and you should take what I say for what it is, which isn’t much.

I love a good disclaimer.

It doesn't start for me until I get down to about the third paragraph...

Well, although I'd assumed that since the only place where the problems occurred was on the Axiom forum(I had no problem with test posts on other forums and I "bought" 7 M80s at the Axiom store)that it was entirely an Axiom forum glitch rather than anything related to my computer. Nevertheless, I ran System Restore to kick back a couple weeks and also ran Malwarebytes, which turned up two viruses I deleted.

Now I'm not sure if either of these was the entire solution(everything appears normal now)or if a change in the forum happened to have occurred almost simultaneously. Why I mention this is that you might try similar measures.

Thats interesting John. I'm still seeing slow text entry in the editor and some wonky behavior once I get past a certain number of lines.

What web browser are you using?

My dual Six-Cores with 32 GB of RAM, running Firefox has the text box working OK.

In other news, Ferraris are really good for trips to the grocery store.

But, where do you put the tomatoes?

You can never have enough overkill.

Never. That's why I eat 10 bowls of Total raisin bran every morning.

The Denon rating is for 2 channels? If you are running a 7.1, the power to the fronts is reduced due to all the speakers, correct? So the Emotiva XPA-3 would be increasing more comparing 7 speakers, correct?

michael_d, had some good points, the power supply is the center of everything for an amp, the picture that i posted for the krell is an amp that is stable down to 2ohms, producing 2000W@ 2 ohms..... i believe that amp weighs about 150lbs, and that is a single channel amp.


free, it would depend on what the other 5 channels are doing, if your watching a movie, and 70% of the audio is coming from the Center channel, then that speaker is going to be using most of the energy. with the surrounds doing almost nothing, as well as the L/R...

if you are listening to stereo and have 7 speakers hooked up, but only 2 speakers are being supplied power, then they will have full use of their amp board, and power supply...

if all speakers are working at the same level, then each speaker "should" receive the same amount of power.

i hope this helps some.

Yes, it does help, thanks.
So one has to be careful in comparing with the source, etc.

i don't know that i follow your last statement, in comparing with the source?

I just meant different source material. Listening to the same material if comparing since different CD's or DVD's would require different power.

that doesn't matter so much... if you are talking about a DVD-A or a SACD, those are mutichannel sources. so that would make things change. but going specifically from a 2 channel CD to a 2 channel DVD. the DVD will hold more information, so should "sound" better because there is more data, so the digital to analog converters in your receiver can make the digital signal much more closely resemble an analog signal.

This is why people still like records, its an analog source, to and analog output...
at the end of the day, our eyes and ears work in an analog environment, so anything digital HAS to be converted to analog for the human body to be able to interoperate it..

i don't know if this explanation helps any or not. hopefully it does.

I don't think that matters in that, whether you use two speakers or 8 speakers to generate 115db peaks, it will take the same number (or very close to) of watts.

Free, welcome. As you probably have now gathered, no, the power to the fronts isn't necessarily reduced. All channels being driven simultaneously at full power is a laboratory test, but essentially never happens in listening at home and a rating based on all channels is rather unrealistic. Typically one or two channels are using much more power than the others, even if all are in operation.

Fred, keep in mind that if you have two speakers instead of one(four instead of two, etc.)playing the same sound, to keep the overall sound at the same dB level, the power used by each speaker would be reduced by half.

http://www.youtube.com/watch?v=PSdHf6yozyc

this is actually a really good lecture on how an amplifyer works, im about 30min though it now, while i get ready for tomorrow.... If you watch this whole lecture you should be good to go for amp design/operation.....

I think that is what I was trying to say.

How about multi channel stereo? I personally don't like it, so was never all the curious to how you get 7 channel stereo out of 2 channel, but if you wanted to really test a multi channel amp out, would this function do it? Now that I'm thinking about it, how does this multi channel stereo funtion work?

I think multi-channel stereo just sends the left signal to all the left speakers and the right signal to all the right speakers, then mixes the signal for the center. It's probably the toughest mode on a multi-channel receiver, I'm guessing.

Yeah, Mike; it's exactly as Ken explained. All the left and right channels are simply duplicates and the center is the combined L/R. This isn't as realistic as the result from the ambience processing modes such as DPLII, since the ambience is a bit different, rather than being simply a duplicate of the front channel. I never use this mode, but it's commonly said that its best use is in a party type situation where a more nearly uniform stereo sound throughout the room is wanted.

No, it doesn't necessarily put more demands on the amplification, for the reason mentioned above by Fred and in my clarifying reply to him. If the overall volume is to remain the same, less power is needed for each individual speaker. If the volume is to be increased, more power is of course needed, but that would also be the case if the volume was increased by just making the mains louder.

Thanks, fellers.