Amplifier Sound

[surveyor]

I was just going to say that! Let's see if I can get this across to even the slowest here:

"All amps sound alike" is an ignorant or willful oversimplification and distortion of the scientific position on this question. What is true is that all modern, competently-designed, solid-state amps will sound alike. This means: 1) flat frequency response, 2) distortion below the generally accepted threshold of audibility, 3) low noise, 4) high input impedance and 4) low output impedance. (If I've forgotten something Chris will no doubt jump in!) And, of course, as long as the amps are driven at levels for which they were designed.

It follows logically that amplifiers (and other electronic signal paths) that deviate from this standard, like many tube amps and especially single-ended triode amps, will indeed sound different. Some "eccentric" (or incompetent?) solid-state designs might also be both measurably and audibly different. But in all these cases the audible differences are due to measurable pheonomena such as frequency response errors, increased distortion, etc. There is no evidence for an unknown or untestable "x factor".

What the argument is NOT about is comparing (say) a Denon receiver to a Cary single-ended triode amp. Of COURSE they will sound "different", since the Cary has large frequency response irregularities and high THD among other irregularities. Some people prefer that. Hey, different strokes...and a different argument!

But when it is claimed that a Denon and a Krell are "obviously" different in sound even though they measure the same that is where the arguement starts! Such a claim requires evidence. The crux for us "scientific" types is that the arguments for such audible differences have no evidence stronger than anecdote, and that the claimed differences tend to disappear when standard scientific methods like double-blind testing are used to test the assertion.

An observation about double-blind testing. DBT, as I have stated before, is the universally recognized "gold standard" for experimental evidence (science does rely on other kinds of evidence, too) in every scientific discipline. It is amazing to me that a method that is relied upon to test theories and hypotheses about things as complex and arcane as genetics and quantum mechanics, and life-and-death decisions about medicine and drugs, is regarded as inadequate to test a relatively trival matter like the difference between two amplifiers!

Well said Rip! It might interest some to know that Denon, Sony have made amplifiers in the past that are in the same price bracket as Mark Levinson, Krell etc.. The POA series from Denon go into the $30 k cost area. I have old magazine buyers guides to back that. I hope I don't have to dig them out of the closet ot back my statement!

Kelly

 

[mtrycrafts]

The following is a post I put up on other forums: I think this goes to the heart of the issue as to why amplifiers and other assorted electronics can sound so different in different systems. This is not a subject that is talked about much in audio, and is generally avoided.

GROUNDING PRACTICES IN CONSUMER AUDIO

As many of us have observed over the years grounding practices in consumer audio have for many of us been a frustrating experience. Compatibility/Synergy are consistently major issues, as well as safety, reducing ground loops, noise and interference. Designers are equally frustrated by this problem. Some of us wish it would go away and others attempt to deal with as best as we know how. There does not appear to be much of any standardization that I, and many others are aware of. Many of us who work in the electronics industry outside of audio who have observed the posts from audiophiles, designers and dealers scratch our heads in near disbelief.
The following is not only an outline for reducing these problems, but a wake up call to this end of the industry. The following is for the application to consumer unbalanced audio, and could well be a possible outline for positive discussion and direction. It is also a way to use Earth Ground to our advantage instead of a problem.
Chassis Grounding:
The following is a technique used in instrumentation for low frequency applications.
The chassis will be earth grounded via the earth ground at the three-prong outlet. The audio signal ground contained in the chassis is not connected to the chassis ground. This will require the design to be electrically isolated from the chassis ground which is easily solved by using nylon stand offs to mount pc boards and isolated bulkhead RCA jacks. (I am going to break this rule later on but bear with me for the moment). The above forces the design to be star grounded at the return of the power supply, which is always good practice to reduce noise and ground loops. However, this does leave the present configuration susceptible to interference from the inputs. This interference can be reduced by the using a simple common mode ac line filter at the AC input and using either a well shielded coax or microphone cable at the line level input. This configuration also poses an additional problem due the fact that we now have two different grounds with two different potentials. In the past I have observed this problem when using a certain brand of rotary switch for a volume control. The rotary switch was not well isolated internally and had enough of a leakage current so that noise was developed when it was used. Moving to a different vendor with higher isolation devices corrected the problem. I have not observed any problem with standard switches for on off applications or anything similar.
I have applied this technique to basic audio chain of equipment consisting of an outboard DAC, line level pre amp, and power amps using the chassis and grounding design I outlined above. The transport that I presently use is a modified consumer device and is equipped with a two-prong plug. The system also has an FM tuner and an old pre amp that is used as a phono pre amp. Both of these devices are standard consumer issue with a two-prong plug. I have observed no compatibility issues with the older style units.
As I outlined earlier I am going to break this rule at one point. The line level pre amp now has a connection from the return of the line stage pre amp power supply to the chassis of the unit. I have now connected earth ground to the analog “center point of the system.” This did not cause a ground loop at all, and to be more precise, for CD playback the inherent ground loops that are typical for unbalanced circuitry simply disappeared. The FM tuner and the old pre amp appear to be unaffected by the center point earth ground. A welcome addition was that the rotary switch that had a leakage problem because of the two different potential levels described earlier no longer had the problem due to center point earth ground.
The use of the system center point earth ground for low frequency applications has been in the textbooks for at least 30 some odd years and has been applied to other low frequency applications. Applied at this level to a simple chain of audio playback equipment. CD playback now has reduced hum and hiss to levels more akin to balanced design than unbalanced design. Playback of FM tuner and Phono pre amp remains unaffected.
One thing that has surprised me relates to the issue of low frequency applications. I was expecting to find problems with the digital portion of this playback chain. I have not found one to date but I think this needs to be investigated further when time allows.
A note to all of the tweakers who read this: I am not recommending any changes to existing designs; in fact I would discourage it.
To DIY folks: You may wish to rethink some of your present chassis/grounding schemes.
To the rest of the industry; this is a subject that not only deserves discussion but an active participation to reach acceptable standards.
The grounding system described above will not address the problem of toroidal transformers mechanically vibrating due to either DC on the AC lines or as I have observed on occasion, low frequency oscillations.
Dan Banquer
R.E. Designs

This is all and well, great info to keep in mind. But, this issue when present and audible is not a mystery X factor that is unknown but perhaps a poor implementation of proper design? It doesn't mean the amp design itself would be faulty if not for the grounding issue?

 

[mtrycrafts]

Mtrycrafts, your tailored rebuttals are interesting to me. My statements are not a product of being new to audio - I've been active in audio gear and music acquisition for 20 years. However, I have never been a scientist in said pursuit.

Just as a parallel to your 20 years experience. I had a plumber with about the same lenght, taught plumbing and I think he may have been a master plumber, or, claimed to be. Yet, the first words out of his mouth on a call on a water heater thermostat problem was that the blanket I have on the heater will destroy the water heater, rust the tank from condensation as it keeps the moisture in or something. What? a 140degree surface condensing moisture? Went down hill from there. He was a plumber all right, full of voodoo and myths. The 20 years didn't immunize him or give him the right knowledge, after all.

The severity of my statements is wholly related to my own, unscientific experiments.

Time to expand beyond it.

My test is simply after I try a new part/accessory/wire/voodoo, do I hear a difference?

And an unreliable test will yield unreliable results, even after 20 years.



Some of my unscientific experiments have been resounding successes -

Or not. No one knoews for sure. One can only hope and guess.



I have had good luck with updating my cables from cheapies to some that are made much better.


Maybe the cheapies were broken then. Price is not an indicator.

A video tape demagnitizer has been cited to clarify reproduction of CD's and a mat on top of the CD is reported to quiet the noise floor. I have not noted that either of these make any audible difference to me, though I'm still trying them out since they are readily available.

Waste of time to even try. No science behing them for these issues. Total voodoo. Maybe I should try psychic reading?

Each change, better, worse, or just different, has been incremental. Only a very few things have been revelatory. My really nice preamp is in the shop. Bringing out the old one is a sore disappointment. Same when I had to bring the old CD back from the garage. Harsh, gritty, bright, digital.]

Never know from unreliable protocol to differentiate the sound differences.

My euphonic and unscientific brain is nonetheless analytical. I listen very carefully to see whether the last alteration has brought improvement. I try to be objective.

Without bias controls implemented, you can listen all you want, you will never know the reality as your brain may be making it up as you go, fooling you. You just don't know no matter how objective you want to be.




At the end of the day however, the exercise for me is directed at the enjoyment of music. This personal and self-serving approach to my own system has wrought an immensely pleasing sound, on somewhat of a budget.

Good for you. You are happy. We cannot rely on it though.

I am not an expert on DBT. In fact, I know very little about it. However, based on my lifetime's experience with Hi-Fi, I consider a failure to hear differences in amplifiers an implication of the testing methodology or the human brain itself.

Well, who said amps have to sound different, or any component for that matter? There is no guarantee of this. But we do know from careful experimentation what is reality and what is not. So, it cannot be a failure of the testing methodology. In fact, a failure of the methodology produces more positive outcomes than null or negative outcomes.
But you are correct, the human brain is an integral part and it is well know to have a mind of its own. One reason why eye witnesses are unreliable at trials. I suppose you never asked anyone to repeat what they said just to be told they said nothing? Or, experimented in school to pass on what the teacher said to the next student then they in turn pass it on? Never the input and output to match? Why?

I keep putting a stick in water and it bends. I see have seen this all my life. I even tried a metal pipe, it bends too until I pull it out. A lifelong experience. But now I know it is an illusion only, science has an explanation, not reality, water doesn't bend it.


Of the articles I've read mentioning aural memory, my recollection is that it is on the order of seconds, not months.

That is what I have read as well from reliable sources in the field, yet many golden ears insist on long term listening? No, you didn't imply this, just an ad on here


Since I'm not a scientist, I don't have to back any of this up with data. See? Much easier. If this forum is "Philosophers and Wisemen", I guess I fit into the former category.



Much as the religious believer would say - faith does not require proof, yet I believe.

 

[Dan Banquer]

"This is all and well, great info to keep in mind. But, this issue when present and audible is not a mystery X factor that is unknown but perhaps a poor implementation of proper design? It doesn't mean the amp design itself would be faulty if not for the grounding" issue?"
I think you missed the point. The real issue is a lack of standards, and as most of us in engineering know, when there are no standards; chaos rules, which is really what's going on here. In addition; grounding is part of any piece of equipments design: it is not a separate entity, to be a touch more emphatic, gounding is the "lynch pin" so to speak.
d.b.

 

[miklorsmith]

In college, I debated religion at length with fellow students. Invariably, despite any inescapable triumphs, we both would leave the table shaking our heads at the other's failure to see the clear superiority of our points. Likewise, I have never observed a political discussion where followers of one party have switched under the spotlight of enlightened thought.

Alas, we may be at such a crossroads. In 1973, US Supreme Court Justice Potter Stewart coined the famous phrase "I know it when I see it" when forced to place an objective definition to obscenity. The sweet sounds eminating from my carefully crafted sound system brings all the justification I need.

On the upside, the key to this hobby is to satisfy yourself and your needs. The path we choose is unimportant.

Now if you want to swing by my place for a half hour for a listening session, I might be able to change your mind. . .

 

[dlorde]

What amazing threads!

I read the AVS 'Win $10,000' thread and was stunned by the lack of logic in many of the arguments on both sides... here was a challenge to those who claim to be able to easily tell the difference between amplifiers by someone who bets $10,000 that they can't do this in a DBT between any amplifiers, using practically any other kit they like, given reasonable equalisation.

It's not a scientific experiment, it's not an assertion that all amplifiers sound the same, it's just a challenge that 'Golden Ears' won't be able to tell the difference in a DBT...

Does anyone want to take it? No - Why? it's not scientific, it won't prove anything, it's rigged, it's a con...

So many requests for the 'experimental results' - when it was a simple challenge - there was no experiment! The results, experimental or otherwise, won't tell you anything (scientifically) useful if the experiment isn't intended to prove or disprove an hypothesis - and, forgive me if I missed it, I didn't see any explicit hypothesis presented.

But if we look at the implications of the challenge, it suggests that if one person can pass the test and win the prize, the implied hypothesis that no-one can tell the difference between any amplifiers in a DBT fails - at the confidence level determined by the probability that one person can pass the test by chance... It doesn't mean that everyone can tell the difference, or that there really is a difference, so it may not be a subjectivist coup, but it would be one in the eye for overconfident objectivists.

The probability theories proposed were pretty weird too - one contributor correctly calculated the probability of one individual scoring 24 out of 24 results correctly, and therefore concluded that if it would take x thousand attempts before a positive result could be expected by chance, he would be prepared to believe it wasn't chance if someone got 24 correct results after only a few tests... Arrrgh!

Personally, I'm prepared to believe the DBT results and their implications. However, as a vain, indecisive, gullible human who wants something to look nice and sound nice, my response is tempered by a number of other criteria, which lead me to spend a fair bit more than I intended on an amp that I would fail to distinguish in a DTB with a cheapo alternative. So be it - the question is, given that the available choice of amps can comfortably handle the load I want to put through them, how much extra am I paying for the inaudible stuff, and/or stuff I won't or can't use (e.*. brand name, reliability, appearance, warranty, upgradability, compatibility, control, features, etc)?

Logic and common-sense always seem to be the first to fail...

Dave

 

[surveyor]

Not directed to me but no one is saying "all" amps sound the same. There are DBT results that show differences. How about 'competently' designed one?

I found some interesting reading listed below.
http://web.ask.com/redir?bpg=http://web.ask.com/web?q=Precise+Acoustics+Monitor+10+Speaker&o=0&page=1&q=Precise+Acoustics+Monitor+10+Speaker&u=http://tm.wc.ask.com/r?t=an&s=a&uid=0F14E45BDF5B40714&sid=1328555BDF5B40714&qid=DBFDF8DF7A9058479D2633F4F466B9C0&io=0&sv=za5cb0dd9&o=0&ask=Precise+Acoustics+Monitor+10+Speaker&uip=04e2038f&en=te&eo=-100&pt=Audio+Magazine+Equipment+Reviews+Part+2&ac=29&qs=0&pg=1&ep=1&te_par=102&te_id=&u=http://www.roger-russell.com/magrevaudio2.htm&s=a&bu=http://www.roger-russell.com/magrevaudio2.htm&qte=0&o=0

 

[mtrycrafts]

The sweet sounds eminating from my carefully crafted sound system brings all the justification I need.

Great. Enjoy


On the upside, the key to this hobby is to satisfy yourself and your needs. The path we choose is unimportant.

Yep, unimportant to anyone, untill extraordinaly but testable claims are made here. Then, some will request for edicence for that claim.

Now if you want to swing by my place for a half hour for a listening session, I might be able to change your mind. . .

Thanks for the invite. How will that listen change my mind about DBT validation of audibility claims between components? I am sure your system sound wonderful but that has no bearing on the discussions.

 

[eleiko]

$10,000 Blind Amp

In the 1980s, Stereo Review ran a blind amp test pitting, on the high end, a Julius Futterman $10,000 tube amp against, on the low end, a $300 Pioneer receiver. There were amps in between, but I can't recall them now. Anyway, the results mirrored those with this test. That is, the listeners (audio writers and critics) hit only about 50% of the time, an obvious indication that there's a lot of guessing going on with these tests. Audio, "serious audio," brings the sort of gratification that goes way beyong what we're actually capable of hearing. Nothing wrong with that except some aren't willing to admit it.

 

[mtrycrafts]

Audio, "serious audio," brings the sort of gratification that goes way beyong what we're actually capable of hearing. Nothing wrong with that except some aren't willing to admit it.

You are right. There is nothing wrong with that kind of enjoyment. Preferences are just that. But, testable claims are another matter

 

[Unregistered]

On the upside, the key to this hobby is to satisfy yourself and your needs. The path we choose is unimportant.

My point exactly. People who question personal experiences as unreliable and not supported by facts have entirely missed the key point of this hobby.

 

[av_phile]

You are right. There is nothing wrong with that kind of enjoyment. Preferences are just that. But, testable claims are another matter

I suppose you enjoy this hobby using "testable claims."

 

[ruadmaa]

"I suppose you enjoy this hobby using "testable claims."

Maybe we enjoy getting the highest quality music possible with the least amount of dollars, have you ever considered that???

 

[Unregistered]

"I suppose you enjoy this hobby using "testable claims."

Maybe we enjoy getting the highest quality music possible with the least amount of dollars, have you ever considered that???

If you can, why not? The urge to get the most with the least is always a compelling initiative.

But have you also considered that there are people who find the highest quality music only in high priced gears? Because they believe that you get only what you pay for.

Have you also considered that there are things made without the compromises that must attend a cheap brand, so they command $$$ in the market?

Have you also considered that we live in a free market economy where the law of supply and demand rules everything that goes commercial? And that people are free to choose the merchandise they want based on their financial capacity and VALUE judgements? No one is forcing you to patronize a $10,000 Mark Levinson, or a $25,000 Wilson Audio. Are they?

So I find it self-serving for people to invoke DBTs to denigrate those high priced merchandise for their untestable claims of sonic superiority, as if only testable claims matter in this hobby.

 

[mtrycrafts]

But have you also considered that there are people who find the highest quality music only in high priced gears? Because they believe that you get only what you pay for.

Yep, happens all the time, and people believe that they get what they pay. Foolish, but so what.

Have you also considered that there are things made without the compromises that must attend a cheap brand, so they command $$$ in the market?

Or, just an illusion of this is what is at work in the marketplace? Or a combination of the two? Or none?

Have you also considered that we live in a free market economy where the law of supply and demand rules everything that goes commercial?

Really? Laws of supply and demand? Marketeering has nothin gto do with it? Human nature has no impact on it?

And that people are free to choose the merchandise they want based on their financial capacity and VALUE judgements?

Of course. Nobody is stopping them, are they?

No one is forcing you to patronize a $10,000 Mark Levinson, or a $25,000 Wilson Audio. Are they?

Nope, you are right.

So I find it self-serving for people to invoke DBTs to denigrate those high priced merchandise for their untestable claims of sonic superiority, as if only testable claims matter in this hobby.

Denigrate anyone? Really? Or, that is just another unreliable observation?

 

[mtrycrafts]

I suppose you enjoy this hobby using "testable claims."

I enjoy this hobby, yes. Did you ask something else?

 

[Unregistered]

But have you also considered that there are people who find the highest quality music only in high priced gears? Because they believe that you get only what you pay for.

Yep, happens all the time, and people believe that they get what they pay. Foolish, but so what.?

Foolish, ha?? This is precisely and predictably the kind of response I expect from self-righteous and pompous textbook robots who think they have a monopoly of what is right and what should be done in a highly personal hobby.

Have you also considered that there are things made without the compromises that must attend a cheap brand, so they command $$$ in the market?

Or, just an illusion of this is what is at work in the marketplace? Or a combination of the two? Or none?

If you don't know, you have my sympathies.

Have you also considered that we live in a free market economy where the law of supply and demand rules everything that goes commercial?

Really? Laws of supply and demand? Marketeering has nothin gto do with it? Human nature has no impact on it?

LOL, Interesting. You recognize human nature as deleteriously at work in Marketing. And because of that, your insistence on DBT, logic, objectivity and the scientific rigors reveal your eagerness to expunge fallible human nature out entirely in this hobby.

And that people are free to choose the merchandise they want based on their financial capacity and VALUE judgements?

Of course. Nobody is stopping them, are they?

You are. You'd want to. By disparaging the personal experiences of forum members who opine differently from your DBT results, you betray some suppresed rage or hidden envy at people who bought expensive gears you canot afford. And you hide behind DBT results that unmistakably give comfort and consolation.

No one is forcing you to patronize a $10,000 Mark Levinson, or a $25,000 Wilson Audio. Are they?

Nope, you are right.

Good. Just so we understand each other. These brands compete in an open market. They don't force their goods on us. In the same way, don't force your DBT results on us and expect us to settle with mediocre stuff.


So I find it self-serving for people to invoke DBTs to denigrate those high priced merchandise for their untestable claims of sonic superiority, as if only testable claims matter in this hobby.

Denigrate anyone? Really? Or, that is just another unreliable observation?[/QUOTE]

Unreliable or not, the observation has its basis. You obviously enjoy screamng your DBT results and testable claims to people who opine differently based purely on untested personal experience. As if only testable claims matter in this hobby.

 

[Mudcat]

When a claim is made, whether it be for the sonic superiority of a $30,000 dollar amp, or the "transparancy" of a $176.50/ft speaker cable. The claim should be backed up by some sort of rigorous testing. The manufacturer made the claim, they must be able to back up the claim. You can bet your house that a drug manufacturer claiming a drug will cure cancer or HIV will be challanged/hounded until that claim is proven.

When someone makes a claim about a product they bought/heard/spit on, they should be able to back up that claim with scientifically acceptable proofs via acceptable test methods.

If you do not like this, do not make claims. Make observations. For instance:

I plugged in these (cables/amp/receiver/CD/whatever) immediately heard sounds I never new were there.

Instead of saying that, say this:

I plugged in these (cables/amp/receiver/CD/whatever) and noticed that the upper octaves seemed a little louder than what I use to hearing. I double checked the levels and they had not changed. Opinions on what may be behind this.


The first sentence will invite snide comments by me and others. The second comment, while actually saying the same thing (almost) will invite valuable input.

 

[Pat D]

Why can't you rely only on your ears?

Foolish, ha?? This is precisely and predictably the kind of response I expect from self-righteous and pompous textbook robots who think they have a monopoly of what is right and what should be done in a highly personal hobby.



If you don't know, you have my sympathies.



LOL, Interesting. You recognize human nature as deleteriously at work in Marketing. And because of that, your insistence on DBT, logic, objectivity and the scientific rigors reveal your eagerness to expunge fallible human nature out entirely in this hobby.



You are. You'd want to. By disparaging the personal experiences of forum members who opine differently from your DBT results, you betray some suppresed rage or hidden envy at people who bought expensive gears you canot afford. And you hide behind DBT results that unmistakably give comfort and consolation.



Good. Just so we understand each other. These brands compete in an open market. They don't force their goods on us. In the same way, don't force your DBT results on us and expect us to settle with mediocre stuff.


So I find it self-serving for people to invoke DBTs to denigrate those high priced merchandise for their untestable claims of sonic superiority, as if only testable claims matter in this hobby.

Denigrate anyone? Really? Or, that is just another unreliable observation?

Unreliable or not, the observation has its basis. You obviously enjoy screamng your DBT results and testable claims to people who opine differently based purely on untested personal experience. As if only testable claims matter in this hobby.[/QUOTE]
.

You are making a simple matter complicated, bringing in all sorts of allegations about motives,

There are testable claims and there are preferences. When someone makes testable claims, many of us want some good reason to believe them. Unfortunately, many times such reasons do not exist. Your preferences are your own business.

What have you got against DBTs? Many audio DBTs are done in people's homes under the same conditions that sighted listening is done. Why do you need to know what you are listening to in order to be able to hear a small difference? Why can't you rely only on your ears?

 

[mtrycrafts]

Why can't you rely only on your ears?

The truth is they don't trust their ears, hence the use of a crutch

If they trusted their ears, we wouldn't have most of these discussions