Axiom Home Page Forums General Discussion Technical Questions Amplifier - General Information Request

As I have trudged throught this HT jungle over the last year or so, I have assembled a decent setup so I can enjoy music and movies closer to the way they were intended to be enjoyed. One of the tangents I chose to ignore was that of separates. I opted for a good quality AV receiver and it has fit my needs. In fact, I have just replaced a Denon 1803 with a 3803 in the last couple of weeks. The 3803 (110 Watts/channel) can act as a pre/pro and affords an opportunity to add an amplifier. I just finished reading about spiff's Stratos.

In simple terms, (not even a little bit interested in charts and articles from experts that get into audio theory to the point of causing me to bleed from the eyes), what does an additional amplifier actually do? How does it enhance an audio setup? Why would I want to consider an amplifier? Is the additional cost for an justified? The tote board is open.

i could write pages worth of nonsense..

but to sum it up. id say. Becuase it might sound better!

Thanks Brandon. My research tells me the same thing. A little deeper and broader soundstage. Noticeable, but not incredible. More money for some return. I really haven't heard anything that knocks my socks off. I hope I'm not missing something in the mix here.

Ray, whatever you read that said that, forget it. There's no way that an amp can affect the soundstage during the amplification process. Special sound processing modes, of course, can sometimes do that. There can be be pride of ownership in having expensive separates and they may have a longer service life, but there won't be any sound benefit except in the unlikely event that a receiver as powerful as your 3803 isn't powerful enough. No, you're not missing anything.

OK, listen, I don't want to argue with JohnK or anyone who knows all there is to know about these matters. Suffice it to say, that although JohnK states his opinion with unqualified authority, there are many, that is MANY, respected reviewers and people whose professional lives are dedicated to the world of audiophile electronic music reproduction, who would not only disagree with JohnK, but laugh loudly at the arrogant presumption of anyone who does not trust his or other people's experiences which conflict with his belief. Yes, that's right, JohnK's authoritative statement that all amps sound the same, have no effect on soundstage, etc., are his opinions, no matter how strongly or states them and no matter how vigorously he attacks any conflicting opinions.

Just because there is a chorus on this board of folks who agree with this idiosyncratic BELIEF, does not make this position correct.

For those who have heard the differences between well made amplifiers, don't be discouraged from speaking by the loudly trumpeted opinions to the contrary of some on this board.

There is no dogma which members of this board must accept. JohnK, believe what you like. It's a free country, and you're entitled to your OPINIONS, like anyone else.

Often makes me wonder if one person's "widened soundstage" isn't another person's "broadened spectrum" or "tightened musicality" or any of the other miscellaneous buzzphrases for "sounded different".

Bren R.

From what I have read, JohnK only passes on scientifically validated information. You can say two receivers sound different until you're blue in the face -- and you might even be correct -- but the brick wall we keep running up against is that some of us don't believe our ears can be trusted objectively. For some of us, hearing isn't believing. For those of us in this camp, we like to see controlled tests performed to either validate or refute those differences.

People who do not rely on such tests are not inferior to those who do. (I realize this might have been implied in the past, and I apologize if I was one of them.) In fact, you probably have an easier time buying audio equipment because you don't have the added burden of questioning the validity of what your ears are hearing. For that I am envious.

If you make it to Southern California, Bren, I'll be glad to give you a demonstration. Each component, including speakers, can influence the width, depth and height of the soundstage.

pmb, what piece of equipment can you suggest which has the exquisite sensitivity of the human ear/brain combination? Do you think it's possible, that there is auditory information which is not measurable by a frequency analyzer, SPL meter, or whatever other piece(s) of equipment you can think of?

I'm having trouble imagining how a non-speaker component can influence the height of the soundstage.

hehehehee...I replied via PM to avoid this inevitable mess.

When I sit on my couch, fireplace directly in front of me, speakers about 12' apart flanking the fireplace, and I hear Astrid Giberto's voice come from directly in front of me, the piano off to my left, and all the instruments placed in space, all this from 2 speakers 12' apart, I have no idea as to how this happens. Do you think there's an instrument which can measure this auditory experience? Do you think it's a result of the placebo effect? or made-up? Or do you trust your ears?

If an electronic piece of equipment can generate a sound, then that sound can certainly be measured electronically.

I know that the human brain is exceptionally good at processing sound information. It was evolutionarily advantageous for our antecedents to be able to pinpoint locations of sound sources in all three directional axes.

But the measurements you speak of have to do with sound. It's more efficient to measure a receiver by cutting the speaker out of the picture altogether and simply measuring the electrical signal that's coming from the terminals. It is my belief that equipment currently available to us can more accurately measure the intricacies of that electrical signal than our ears can measure pressure waves.

Yes, but what are you measuring?

In reply to:

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There's no way that an amp can affect the soundstage during the amplification process.

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John, to be fair, shouldn't you have said "There's no way that a properly designed amp can positively affect the soundstage..."?

After all, an amp is only supposed to take the input signal, make it louder, and nothing more. If it's badly designed, couldn't it alter the original soundwave in ways other than amplitude?

2x6,

The re-assembly of two distinct sound sources (stereo) into a coherent canvas of sound occurs in the brain. The effects of this imaging on an individual person cannot be measured. However, the sounds CAN be measured accurately. How do you think a recording studio works? That same acoustic energy that you're hearing -- as interpreted by your speakers -- once emanated from an instrument and passed into a microphone before it was digitally written to the CD in your Ah! Njoe Tjoeb player.

Exactly, pmb! A recording studio does not use dials, analyzers, meters and whatever to monitor the recording and mastering process - ultimately, they use speakers with some guy/gal listening, tweaking, listening, tweaking.

On the contrary. Have you actually seen a recording studio? There are dials, sliders, meters, monitors, and analyzers all over the place.

Right, but ultimately, they kick back, roll a doobie, and listen to the music - the ear/brain thing - the ultimate music analyzer.

ok. I'm bowing out before this tangent spills over onto the third page...

In reply to:

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If you make it to Southern California, Bren, I'll be glad to give you a demonstration. Each component, including speakers, can influence the width, depth and height of the soundstage.

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I'll take a pass on the travel... it's no fun to travel to do for free what one can stay at home and do as work.

All I meant was you hear these same buzzphrases all the time (this cable/cord/woodchuck will --------) It makes me wonder what percentage of the population uses the same metaphor for the same phenomenon.

Bren R.

Looks like you guys had some serious fun while I was asleep last night. I have still seen nothing beyond my initial conclusion that convinces me I need to be saving my spare change to go out and get a big honkin' amp.

Ive been trying to follow all this discussion across several threads. It seems that most people have the opinion that amplifiers shouldnt/dont make a difference.

I'd like to ask a question (Im talking about amplifiers here, not receivers that are made to change the sound with surround effects, etc)...

Considering that amplifier are rated by their manufacturers at % of total harmonic distortion. Isnt it logical to assume that they have tested to make sure that is the case?

A 0.07% THD would seem to mean that over the entire frequency range that the amplifier wouldnt change any input sent to it more than that amount. Are these ratings wrong/misleading?

If the ratings are correct, then is it possible for the human ear to hear that low of a distortion?

Jon, specific published figures result from what the engineers tested in the lab, and certainly aren't "lies", as some rather naive comments claim. Whether they're misleading is another matter; first, the test conditions(e.g. frequency range)may vary, and in addition there may be an implication that the very low distortion figure is of audible significance. The audibility of THD varies with the type of program material, but something on the order of 0.07% is well below audibility even on pure sine wave test tones. It's frequently said that distortion on music would have to be greater than 1% to be audible(e.g. one of the FTC regs uses a 1% distortion standard)and on complex full orchestral material the threshhold in David Clark's ABX tests was about 3%.

So, there's a bottom line which principles of scientific engineering teach us(supported by blind testing results)and which certainly isn't something as trivial as personal opinion based on casual listening. Amplifiers having flat frequency response from 20-20,000Hz with inaudibly low noise and distortion(common these days)don't create audible differences in sound, regardless of the nameplate or pricetag.

Our senses lie. Why should I trust my ears more than I trust my eyes? The human sensory array/brain processing unit is not, by far, the most accurate thing in the world.

And that's all I'm saying for now.

I can't believe I'm going to join in this fray....

The bottom line is those lines look sloped. All the science in the world isn't going to make them look straight. The same can be said for audio illusions. Just because something can be scientifically measured to tell you it should sound a particular way, doesn't mean it's going to sound that way to you.

I'm not trying to join either camp on this issue, but your optical illusion example doesn't really help your case.

OK...that's the last I'm posting on this. I feel dirty now...I've got to shower.

Yes, but all the science in the world can measure them as straight. My point was that our senses cannot be trusted to give us accurate information, not that amplifiers are like sloped lines.

And my point was what is accurate? If it graphs as accurate, but sounds like crap? Or is accurate something that sounds great, but graphs like crap?

Personally I'll take what sounds good over what graphs good any day.

Damnit...now I've got to shower again.

Good point. Perhaps this was not the correct discussion to inject that thought into.

What is being measured? A single frequency test signal? A sine wave?

OK...I'll be a goat and jump into this tar pit. There is a huge difference in the sound of amplification. I used to be a firm believer that electronics all sound the same. I agreed with what Julian Hirsch used to preach; Solid state amplification, if created with low harmonic distortion and noise figures and a flat frequency response, will all sound the same.

I have changed my mind over the last several years. While the theory is completely correct, I have come to the conclusion that in practice, amps are not CREATED the same. My 1986 NAD reciever put out 75 watts per channel and sounded bigger and fuller, with less strain, than many of today's 100X5 receivers. I have recently (a few years ago) upgraded to an Outlaw 950 and a Parasound HCA-855a 85X5 amp. I bought the amp before the Outlaw 950. I hooked the amp up to the NAD, and the Parasound added more depth and precision to the soundstage, as well as better bass. (and my NAD was quite good!) While the main specs (response, THD, and noise) may be comparable, and published WPC may be the same, real world power may be completely different. A 100X5 Sony reciever may have good published specs, but in real life may strain or even clip before reaching outputs that my 85X5 Parasound can achieve.

Not only must real power be taken into consideration (usually tested with a resister of known CONSTANT value), but we must also take the speaker into consideration. A speaker is not an 8 ohm resistor. While it may be considered to be nominally 8 ohms, in real life it may range from 2 or 3 ohms to 40 or more ohms depending on frequency. An amplifier's ability to handle these difficult loads may be what leads to differences in overall sound.

The M80 has been referred to as an "easy" 4 ohms. Many people have come here asking if brand "X" amp or receiver can drive the M80s. The truth is, if they can't, they will sound very different than an amp that can drive them successfully. More important than WPC is amperage output. Higher amperage output (higher current) allows 4 ohm speakers to be driven more easily.

Getting back to the M80's "easy 4 ohms". It is nominally a 4 ohm speaker because it hovers between 3.5 and 5 ohms through a good majority of its frequency range. On the other hand, the Paradigm Reference 100's are a more difficult speaker to drive. Although they have much of their response frequency's resistance well above 6 and 8 ohms, they dip down into the nearly 2 ohm range in spots. This complex resistance can cause lesser amps to cook if loud music is played in these frequency ranges! (or drive the amp into clipping, cooking the speakers instead).

What I am trying to say, is that all amps may be equal in driving a constant resistive load, real world interaction between amplifier and speaker can and does indeed lead to differences in how actual sound is output from the speakers. While published output wattage, THD, and noise figures may be compararable or even equal, differences in the ability to deliver high current and handle difficult reactive loads is what I believe makes amps sound different.

(these thoughts are mine and mine alone and do not neccessarily represent the truth. all opposing views are welcome, but food and beverage throwing, deficating, hysterical laughing, or pointing and screaming will be taken personally)

Differences in power vs power rating and such that you mentioned are what I, personally, would accept as things that would change the sound of an amp. However, I just have my doubts that well designed (ie, not Sony 5x100 BS amps) should sound the same at the same volume levels. If the amps are equally capable of driving the load of the speaker, they should sound the same.

Baah.

I've a burning desire to learn what the NRC has found, regarding amplifier neutrality. How much of their results are public, or is it more of an empty lab where companies can test things at?