Blind Listening Tests & Amplifiers

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I've left this thread alone for some time as the content has descended beyond pointless, however, I do feel obliged to comment on the audiometry/graph joke.

In fact, if the test was of any use whatsoever you most certainly should have been given a graph;)

Human hearing is characteristically not flat - despite what any of us might think/claim.

Also, the question about age is very relevant in terms of comparison. Alas, we do not improve with age (like so many fine wines!).

BTW, I'm not suggesting for a moment you do not have good hearing, just a couple of pertinent facts .........

cheers
mark

PS: For those really serious about this, they should probably see their doctor every 6 months or so to have any extraneous wax removed .... plays havoc with the higher frequencies :bulb:
 
Re: Worlds Cleanest Amplifier.

mrfeedback said:
The only amplifier in the world to challenge a theoretical limit unprecedented harmonic distortion levels of less than 1000 parts per billion
Over the past 50 years it has taken the typical audio manufacturer 50 years to reduce distortion at 20kHz from .1% to .01%. Now, with a single revolutionary technological advancement, Halcro™ has reduced distortion to less than 0.0001%. In fact, all unpleasant distortion in the output stage has been virtually eliminated.



I said exactly this sort of stuff way back in this thread, and now we have documented proof. ;)
For you 'null testers', your amplifiers need to be as good as the Halcro to be indistiguishable, and if they are not, then the internal distortion products will be audible, and then by definition distinguishable.
0.01% amplifiers are distorted enough for the human ear to detect and categorise the distortions, especially IMD products.

I rest my case.

Eric.

Halcro, another Aussie world beater.



You only forget that the halcro distortion spec is specified with an unrealistic load. As soon as you put a real speaker to the output, the distortion of the amp-speaker combo will be about 1% second and 0.3% third harmonic distortion at 1 watt power assuming a better than average high quality speaker driver. This distortion will increase with the square law function as the power rising - so at 10W you can reach up to 100% distortion with your amp "challenging a theoretical limit ". This distortion is not a speaker distortion, rather coming from the bad speaker/amp interface. It is solely from the eddy current and thus from the volage source nature of the amp. Any amp with near 0 output impedance will produce this kind of distortion.
With a better designed speaker amp interface this distortion can be substantially reduced/ eliminated.

Remember, one of the major tweaks of the Carver challenge was to match the output impedances, to simulate similar real world distortion behaviors for the two very different amps.


Any other distortion from the magnetic and mechanical nonlinearities of the speakers will add on top of this.
 
More details

I´mm 33 and was 31 when the test was taken. I had relatively "flat" hearing curve with a small deviation on one ear in a narrow band (dirt/vax in my ear I hope :)).

The sensitivity was 10dB better across the range compared to the average test result. Don´t know if that is average for a Swede or a Human (yes Swedes are also humans :)) and don´t know about age groups.

I can hear 17Hz - 20.000.Hz. Sinewaves.

Carlos,
lol ;)

Eric,
right on and correct as usuall.

This thread is sooo fun!

Happy listening again guys :D

/Peter
 
"In fact, if the test was of any use whatsoever you most certainly should have been given a graph"

What do you talk about???

I did the test in order to find out if there was any wrong with my hearing. I wondered this because I had health related issues that might have had something to do with the ear/hearing (balanceproblems/dizzyness).

I found out what I wanterd to know so this test was VERY useful.
I certainly did not do this test in order to brag about my "golden ears" as you seems to believe.

Jeeeez... once again!

/Peter
 
Re: Older Ears Can Be Better Than Younger Ears....

mrfeedback said:


Hi Peter,
With agieng, it is to be expected that your (our) hearing sensitivity and bandwidth degrades, however the ear/brain system is self learning, and according to aural experiences can actully become more discriminating.

The more of, and better systems that you get to experience, the bigger and better the database of 'captured' sounds you will accumulate, and become an even better judge of systems.
Also be aware that one's sonic preferences may change during this period also.

These factors are ones that our younger bretheren seem not to understand.


Eric.

Eric,

I suspect you are right as my hearing are way more sensitive now than 5 years ago. I do not suggest my actual hearing is better, but the nerve/brain function to detect/analyze/hear sounds seems indeed to be better with training (as most other human skills and functions).

I would be very curious to know the age of the participants of this thread.....

/Peter
 
33

Peter,
Congratulations, I'm 33 too!:cool:
But I'm not so sure how the human hearing can be measured.
Maby it can.
Or you listen to a particular sound, or you don't.
I'm not a specialist, but how to measure +10db inside your head?
Did you see the man doing it's job?
Or did he boost a signal by 10 db and then you heard it?:scratch:
The human hearing is not at all flat.
And 20 khz seams a little high to me...
Can you hear the stereo pilot tone (19khz) on your tuner?:scratch:
And if anyone says they can hear above 20khz, they may detect the "brick wall" on cd players!
Cool!:devily:
 
I recently stumbled across this forum. This thread was the 2nd I've read and I've found it very interesting.

There are a couple things that struck me as important and worth adding to the conversation. My interpretation of NW's post is not that all amplifiers sound the same, but that in order to eliminate any possibility of the "proud poppa" influence when auditioning equipment, a double blind and/or null test is a very good way to evaluate equipment.

The Carver test does NOT prove that all amplifiers sound the same. It only proves that a group of very experienced listeners were not able to distinguish between the amps in question("proves" isn't quite the right word, but I think many of you will understand my point). Does this mean that the electrical signals leaving the amplifiers were identical? Not necessarily. I means than any differences in the signals leaving the amplifiers did not result in an AUDIBLE difference in the sound generated by the speakers.

Does changing the type of capacitor change the characteristics of an amplifier? Probably. But is that change enough to be audible? How do you know? How do you know that the perceived difference is not do to psychological factors? Do you CARE whether or not the difference is do to psychological factors?

Personal Anecdote: I do a lot of cycling. About a year a go I tried a new energy bar. About 20 minutes after I ate it, I started to feel significantly better, stronger. I tried it again a couple days later, same result. I've noticed that when I eat this bar prior to riding, I feel better, ride faster (yes, I use a cyclometer so I am actually faster). The question is this: Does the bar actually have that much of an effect or is it just a placebo effect? I don't know enough about what is happening biologically/chemically to know the ACTUAL (REAL) effects. However, I DON'T CARE (aside from any possible negative effects). I don't want to know. All I know is that I ride faster and feel better. If it is a placebo effect, at least partially, I don't want to know. That knowledge might reduce the effects, which is something I don't want to happen.

If you are happy with the current method/paradigm/procedure you use to determine the level of quality of a particular piece of equipment. So be it. If, without any blind or null testing, amplifier A sounds better to you than amplifier B and you think the difference is worth whatever additional costs might be involved, then do it. Maybe you can genuinely hear a difference, maybe its imagined, maybe you don't care. But some people are not happy with that. Some people may want to find out if there are any AUDIBLE differences with any possible psychological effects removed. The only thing a blind test tells us is whether or not the people involved can hear a difference.

I do like the previous point made about measuring the output signal (I apologize to the person who submitted it for not properly identifying you. I don't remember who submitted the post and haven't been able to re-locate it). If a signal difference is too small to even move a driver cone, how can it possibly be audible? Which makes me wonder about the Halcro. At what level does distortion become inaudible? And does it make any sense to lower the distortion levels beyond the point at which they are already inaudible? Is the Halcro really any better if it's very impressive specs don't translate into an audible difference FOR THE PERSON DOING THE EVALUATION?

I personnally tend toward both subjective and objective evaluation. Sometimes I really don't care if a change I made would pass a double blind or null test. Other times, I would really like to know, without a doubt, that a change I made had a noticable and positive effect on the sound of my equipment.

In defence of NV, some people may have a need to make sure what they are doing will make a difference with regard to null or blind testing before they spend a tremendous amount of money. To each his own.

My $0.02.
:crazy:
 
Pan, at the time of my epiphany, when I started doing some rigorous controlled testing to prove that Lipshitz guy wrong, I was 28. That was (gulp!) twenty years ago. I've lost a few kHz to presbycussis over the years (I'm probably topping out at 15K these days), but I still have no trouble identifying the string gauge on my guitar by the sound.
 
"In fact, if the test was of any use whatsoever you most certainly should have been given a graph"

What do you talk about???

I know this may come as a surprise, but I try to talk in areas where I have some training/expertise .... a novel concept for a couple of people here, I suspect.

I do not comment on the electrical theory side because compared to the masses here I am an idiot/novice.

Medicine, however, happens to be what I do for a living so you will forgive me if I felt bold enough to comment.

Properly performed audiometry should be done in a sealed, sound-proof booth, using a combination of sine-wave and white-noise sources in a combination of ascending/descending SPL patterns. The end result should be a calibrated graph over the test frequency range. And this should be done after someone has made sure your ears are not full of wax!

A simple comment, "your hearing is 10dB better" on it's own is not too helpful. I grant, it's better than your GP saying, "jeeez ..... your as deaf as a post", or even worse you not hearing the GP at all ;)

Again, please read what I actually write, cf what you might infer. I have made no statement about your hearing per se, just what can be reasonably concluded from the information provided and more importantly, what people should be looking for if they want to assess these things properly.

"Jeeeez... once again!" ....... Indeed :(

regards
mark
 
Not Plecebo Effect....

Bane2871 said:
Personal Anecdote: I do a lot of cycling. About a year a go I tried a new energy bar. About 20 minutes after I ate it, I started to feel significantly better, stronger. I tried it again a couple days later, same result. I've noticed that when I eat this bar prior to riding, I feel better, ride faster (yes, I use a cyclometer so I am actually faster). The question is this: Does the bar actually have that much of an effect or is it just a placebo effect? I don't know enough about what is happening biologically/chemically to know the ACTUAL (REAL) effects. However, I DON'T CARE (aside from any possible negative effects). I don't want to know. All I know is that I ride faster and feel better. If it is a placebo effect, at least partially, I don't want to know. That knowledge might reduce the effects, which is something I don't want to happen.

Hello Bane2871,
20 years ago I used to race cycles, road and velodrome.

Sundays were post race day, and the day for some easy longish distance riding to get the soreness out.
I would ride all over the city and drop in and see a few mates, and of course we would have a beer together.
Being ultra fit, the alcohol would go straight to the head, and give that happy sense of well being, however getting back on the bike was a whole different thing.

After just one 375 ml bottle of standard beer, all my strength was taken away, and even moderate climbs were a task.
It seems that even that small amount of alcohol inhibits oxygen uptake dramatically.
However after about 15 minutes back on the road, the body processes and removes this alcohol, and I was back to being completely sober again - until I dropped into the next friend's place that is.

Try taking a biddon of very strong tea with castor sugar dissolved into it.
This gives caffeine boost, sugar boost, wets the mouth and makes you feel good too. ;)

Eric.
 
Re: Re: Re: Re: purplepeople wrote:

mikek said:



slew rate=6.18*freq*V(out)peak:nod:

Maximum ouput voltage swing has NOTHING to do with slewrate.
Still don´t know what you talk about.

An opamp or video buffer with several hundreds of MHz BW and slerate of 2000V/uS must be able to swing several kV as well if I get you right???

I guess Elantec, BB and AD is just making those numbers up then..

/Peter
 
mefinnis said:


I know this may come as a surprise, but I try to talk in areas where I have some training/expertise .... a novel concept for a couple of people here, I suspect.

I do not comment on the electrical theory side because compared to the masses here I am an idiot/novice.

Medicine, however, happens to be what I do for a living so you will forgive me if I felt bold enough to comment.

Properly performed audiometry should be done in a sealed, sound-proof booth, using a combination of sine-wave and white-noise sources in a combination of ascending/descending SPL patterns. The end result should be a calibrated graph over the test frequency range. And this should be done after someone has made sure your ears are not full of wax!

A simple comment, "your hearing is 10dB better" on it's own is not too helpful. I grant, it's better than your GP saying, "jeeez ..... your as deaf as a post", or even worse you not hearing the GP at all ;)

Again, please read what I actually write, cf what you might infer. I have made no statement about your hearing per se, just what can be reasonably concluded from the information provided and more importantly, what people should be looking for if they want to assess these things properly.

"Jeeeez... once again!" ....... Indeed :(

regards
mark

What I didn´t like about your post the comment "to be of any use at all.." (or something like that). In order to make such a comment it seems to me that you would need to know the purpose of the test, which you din´t know.

Simple as that :)

Thanks for your expertise comments in this latest thread though, most of the points you make was done in the test

/Peter
 
to this forum, and it's good to see a range of opinions in the subjective/objective debate. Here goes:

1. It's important to be able to say "I can't hear a difference". Michelson & Morley presumed the existence of the ether which they were trying to measure, but had the courage to say their experiment had failed. From it we learned a lot.

I assume we've all made many upgrades and tweaks to our systems over the years, and if you're like me some changes made a night-and-day difference, and others were not. Personally, I want as many of the former and none of the latter as possible.

Ultimately, being able to say "it makes no difference" is essential to avoid being taken for a ride by charlatans.

2. I'm very happy - it's my normal practice - to let a subjective decision be the final arbiter rather than objective measurements. I'm even happy that this can be an unreliable and unrepeatable experience, and accept that this sometimes leads to flattery instead of accuracy.

Here's the 'but', though: there's a tendency to attach technical statements to subjective judgements e.g. "negative feedback makes your amplifier sound bad". This sort of statement implies there's an underlying physical mechanism at work, and this *must* be the subject of scientific inquiry. To make technical statements, but be unable to justify them technically, is not something I can stomach.


Cheers
IH
 
Re: Re: Re: Re: Re: purplepeople wrote:

Pan said:


Maximum ouput voltage swing has NOTHING to do with slewrate.
Still don´t know what you talk about.

An opamp or video buffer with several hundreds of MHz BW and slerate of 2000V/uS must be able to swing several kV as well if I get you right???

I guess Elantec, BB and AD is just making those numbers up then..

/Peter

Voltage swing has nothing to do with slew rate, that's right,
but slew rate has a lot to do with voltage swing. Any op amp
can swing almost rail to rail voltage at sufficiently low frequency.
However, to do this also at high frequencies it needs a good
slew rate. For an output signal v(t) we need a slew rate of
max dv(t)/dt, which for sine waves simplify to the formula
mikek posted.
 
welcome

Welcome, Ian Harvey.

You made a very valuable contribution to this thread.
In fact, you almost took the words out of my mouth, because I'd say the same.:cool:
Stick around, this is still going strong.;)
In the end, we may even find that the Bryston amp plays much better than the Onkyo AV amp, even at low volume!:devily:
 
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