Measurements and the Correlation of What We Hear

[mep]

It's probably time to put this thread out of its misery. Only a few *got* my original point and the rest keep acting like they have a fist full of measurements stuck in their back pocket and want to argue about what they don't really have. Specifications are not measurements people. For those that continue to profess their love for "measurements" and think somehow they are one up on those that rely on their ears, they need to change that and say they love specifications first and their ears second. I find it amusing that people will actually say they don't trust their ears and would rather place their trust in a set of specifications.

 

[fas42]

Okay. To go a step further, do we acknowlege that if a system is not "perfect" then it is distorting, and that some types of distortion are more acceptable than others. In other words, you can't just throw all distortion in one bundle, and proclaim that if there is distortion there, of any type, then it is automatically "bad", as in that it makes listening to the music unpleasant, irritating, fatiguing, etc, etc.

Frank

 

[Phelonious Ponk]

I find it amusing that people will actually say they don't trust their ears and would rather place their trust in a set of specifications.

I would find that amusing, too. But first I'd have to find it.

Tim

 

[RogerD]

Too bad that any type of concensus could not be reached here. Maybe if a manufacturer quoted EMI/RFI rejection using a spectrum analyzer or there was a accepted universal scale for the degree of clarity produced I would get excited. There is so much low level noise present in most systems,are you really at the maximum of what your electronics is capable of? The answer is nobody really knows unless you know there's a problem and take measures to mitigate it.

 

[garylkoh]

To a large degree, I agree with what you've just posted, Mark. There is an ocean of a difference between reading manufacturer specs and taking in-situ measurements. And since none of us listen in anechoic chambers, each one of us has to factor in the deeply profound impact our listening environment has on the sound. Then there is the problem of defining that pesky term, i.e., that it sounds *better*. Better in an objective sense (instead of a personal preference) probably requires a goalpost or set of standards, and lord knows there is no consensus there.

As a side note, I think there are a few others besides Vlad Lamm who are in tune with the inner workings of the ear: Earl Geddes, Ken Stevens, and of course the folks at Harman to name just a few.

There's information on our own Tech Talk thread on how we hear. Links to some of the papers here:
http://www.whatsbestforum.com/showt...em-and-acoustics&p=27774&viewfull=1#post27774

 

[fas42]

Yes Frank, not all distortions are "bad", for example, many love the odd harmonic distortion of tape recorded at levels above say -3db, and how it enhances the "edge" between instruments. Large doses of second harmonic can make sound "syrupy" and easy to listen to..although dynamics are toned down too. Apparently, a great deal of audiophiles do not want to hear the recording as is (include me in that lot) all of the time.

Tom

Of course, you should want to listen to all recordings, at the first instance, as they originally sounded from the tape master, analogue or digital. It's fascinating with good CD playback to hear the pristine cleanness of a modern digital recording, and then go immediately to the golden era of recording, analogue tape and tubes, and hear the lusciousness of those harmonics interwoven with the sound, some of the classic pop songs have an amazing richness of tone, an embellishing especially of male vocals that's very enticing. It's not "correct" of course, but true to the recording technology and intent of the time ...

Frank

 

[RogerD]

Roger, I know you are big on noise reduction, but I am not sure I can understand how much it impacts your system....what I am saying is, given you listen to speakers, in a room that is already say 30 db of background noise (or quiet), how the heck are you hearing all this noise when I assume your noise is down maybe 85 db or even more by the time it is output from your speaker......

I agree that especially with headphones, where you could be attenuating the outside world noise by say 25 db, then noise is more apparent to some degree....if you turn the sound up way way loud.

But maybe you refer to all distortions as noise?

Tom

Hi Tom,

Noise is a form of distortion,but what I talk about is what Walter Fields references as "noise" in my signature. Or what Steve McCormack talks about referencing transformer design.

"First of all they provide complete immunity from DC and RFI, and well-designed units have outstanding common-mode noise rejection (CMRR)."

What I have found is that "current noise" is a bar to extreme clarity which is missing in all but the best systems. low level noise effects the reproduction to such a point,when this noise factor is reduced to be a non-factor,the results can be startling.

I read this review of the VRE-1 preamp in the comments made are exactly the attributes of a ultra low noise system or piece of equipment.

" But true transparency as delivered by the........now VRE-1 is actually warm, smooth yet ultra intimate and detailed like only live music can be......
....the VRE-1 does not provide a clear window on the music. Instead, it tears down the window frame and panes, grabs you and sticks your head deep into the recording event, into the reality of the creative moment. Virtual reality perhaps but for just an instant your reality in your listening room."

I related to the reviewers description......the level of transparency and resolution....puts you in the moment. The illusion is so real because only the scale has been reduced. Dynamics,clarity ambient detail,timbre,ect,ect is dependent on removing, this low level noise and distortion. Most high end equipment I think is capable,but I think a lot is being left on the table and it doesn't have to be,if the focus is removing RFI,EMI,CMRR,ect.

I hear the noise not by hearing it's presence, but only when it is removed.

Now if this "noise" can be measured and I think it can,but it is a process and I think it is a uncommon understanding,I'm all ears.

Roger

 

[fas42]

Nicely put, Roger ...

Frank

 

[Gregadd]

Yes Frank, not all distortions are "bad", for example, many love the odd harmonic distortion of tape recorded at levels above say -3db, and how it enhances the "edge" between instruments. Large doses of second harmonic can make sound "syrupy" and easy to listen to..although dynamics are toned down too. Apparently, a great deal of audiophiles do not want to hear the recording as is (include me in that lot) all of the time.

Tom

No we don't love 2nd order ndistortion. We may find it less offensive given a choice.

 

[mep]

Yes Frank, not all distortions are "bad", for example, many love the odd harmonic distortion of tape recorded at levels above say -3db, and how it enhances the "edge" between instruments. Large doses of second harmonic can make sound "syrupy" and easy to listen to..although dynamics are toned down too. Apparently, a great deal of audiophiles do not want to hear the recording as is (include me in that lot) all of the time.

Tom

Tom-How much time have you spent listening to a pro 15 ips 2 track machine vice listening to your old 4 track Akai at 3 3/4 or 7 1/2 ips?

 

[fas42]

It is sort of sad that audio people have largely given up on the exercise of reducing distortion to effective inaudibility. There was a fling with the concept in the 70's but because that was poorly done, and in many ways was purely a marketing exercise, the very process and concept of attempting to excise all distortion from a system now has a bad odour to it. So now distortion has become a ball of plasticine of almost infinite levels of complexity and expense, you mold and shape it to suit your own preferences and ideas, rather than seek to eradicate it. No wonder the new generations don't get it ...

Frank

 

[mep]

It is sort of sad that audio people have largely given up on the exercise of reducing distortion to effective inaudibility. There was a fling with the concept in the 70's but because that was poorly done, and in many ways was purely a marketing exercise, the very process and concept of attempting to excise all distortion from a system now has a bad odour to it. So now distortion has become a ball of plasticine of almost infinite levels of complexity and expense, you mold and shape it to suit your own preferences and ideas, rather than seek to eradicate it. No wonder the new generations don't get it ...

Frank

I disagree with everything you just said. The Japanese did win the spec war back in the 1970s by applying massive amounts of negative feedback in order to increase the number of zeros after the decimal point of their distortion specifications (not measurements). And this was really for the benefit of those that love specifications (even thought they think they love measurements) because it made them feel good to see so many zeros after the decimal point and they just knew it had to sound better.

High end manufacturers learned how to make their circuits more linear without increasing feedback and we steadlily saw distortion numbers drop as well as the amount of negative feedback applied. Now we have some circuits with no feedback and they still have excellent distortion specs like Ayre's new preamp.

 

[fas42]

I disagree with everything you just said. The Japanese did win the spec war back in the 1970s by applying massive amounts of negative feedback in order to increase the number of zeros after the decimal point of their distortion specifications (not measurements). And this was really for the benefit of those that love specifications (even thought they think they love measurements) because it made them feel good to see so many zeros after the decimal point and they just knew it had to sound better.

High end manufacturers learned how to make their circuits more linear without increasing feedback and we steadlily saw distortion numbers drop as well as the amount of negative feedback applied. Now we have some circuits with no feedback and they still have excellent distortion specs like Ayre's new preamp.

But Mark, every time someone talks of rolling tubes, or the sound of one extremely expensive amplifier as compared to another, or the impact of replacing a couple of capacitors in a speaker crossover, that's exactly what one's doing: manipulating or managing the distortion spectrum to suit one's tastes ...

Frank

 

[fas42]

INow we have some circuits with no feedback and they still have excellent distortion specs like Ayre's new preamp.

I looked at their website: exactly what you started this thread in respect to, as far as I could see there was not a single indication or measurement of the distortion levels of their preamps ...

I've just followed through and looked at JA's measurements of the KX-R: very dodgy, barely acceptable, if someone released an audio opamp with those sort of measurements these days they would be laughed out of the room. Sorry, no cigar ...

Frank

 

[mep]

That is not the Ayre preamp that I'm referring to that JA measured and gave high praise to both for its measurements and its sound. And these were real measurements. Frank, if you love the sound of super high negative feedback, go for it with your amp that you have told us you are going to build.

 

[MylesBAstor]

That is not the Ayre preamp that I'm referring to that JA measured and gave high praise to both for its measurements and its sound. And these were real measurements. Frank, if you love the sound of super high negative feedback, go for it with your amp that you have told us you are going to build.

What about the Soulution amplifier that has received all around great reviews?


Philosophy
An ideal amplifier is load stable and strictly shows a level and phase true behaviour. And this without long signal paths or those tricks like an overly high amplification – open loop gain – or a very high negative feedback as they are often used in solid-state technology. Such amplifiers may deliver good measuring data, but are soundwise often inferior to simpler valve circuit designs.
Yet the soulution 710 was also to be extremely fast and have an ultrawide bandwidth (1 megahertz/-3dB) and a high current capability – which in turn cannot be realised with valves and output transformers. The unique and sophisticated circuit design of the soulution 710 opens up sonic qualities which so far have been regarded as being incompatible: precision, velocity, stability and power. Now they are united for the first time – only to serve the music.


Layout
The entire stereo power amplifier has been designed with a consistent dual-mono layout. Both the left and right audio channels feature identical audio amplifiers. The high efficiency power supply has also been designed accordingly with separate channels. The housing forms an integral part of the whole amplifier concept. It has both been designed to cool the power transistors and also to minimise microphonic interference.


Amplifier
Right after the input sockets the music signal is buffered in the soulution 710. It is then present as a low impedance signal at the input of the subsequent correction amplifier. An extremely fast OP amp whose feedback captures deviations very fast and precisely due to its high processing speed provides a corrected, yet still unamplified input signal.
High time for the actual centrepiece of the soulution 710: the «fixed gain» voltage amplifier. The music signal travels through this ultra wideband amplifier stage with no feedback to the input in just about 10 nano*seconds – notabene with a maximum level deviation of 0.1 decibel.
This ultralinear gain stage can demonstrate its full precision only under constant thermal conditions, which is why we have packed it together with the correction amplifier in one common module grouted with artificial resin. Finally 14 bipolar power transistors per channel, mounted onto a massive copper rail and permanently temperature-controlled for a constant quiescent current, ensure the huge current capability of the soulution 710.
We’re talking about more than 60 amperes.


Power supply
A stable supply voltage is the nerve centre of a good sounding amplifier. Circuit sections that don’t process audio signals should not be able to affect them, either. Therefore we use no less than 10 dedicated power supplies for those circuit sections with each stereo amplifier. In order to suppress mechanical interference from the power supply as well, we have isolated it mechanically from the rest of the housing.
The power supply has a sub*chassis which is connected to the body through vibration-damping rubber buffers. This power supply of the soulution 710 consists of two massive 1,000 VA toroidal mains transformers, filter capacitors with an overall capacitance of nearly 250,000 microfarads and rectifiers with a discrete design.
Hence the soulution 710 has sufficient power reserves to carry the full impulsive nature of the music to the loudspeakers.


Operation
The display indicates the operating status or potentially occurring faulty conditions. Comprehensive protection functions ensure a safe operation and a long life. The 710 stereo power amplifier is equipped with a level limiter (softclip) as well as overcurrent and overheat protection circuits. Via the front panel buttons the Power, Mode and Input functions are operated.
By pressing the Power button, the operating status ON or OFF may be selected. Pressing the Mode button will transfer the control of the turn-on procedure to the 720/721 preamplifier (LINK).
Pressing the Input button will select the desired input. The respective other input will be muted.


Connectors and start-up options
The 710 stereo amplifier features unbalanced and balanced input sockets per channel. Via the rear panel switches you can set the display brightness and the start-up options for the power amplifier. The connectors of the LINK system are also located here.

 

[fas42]

As a quick side note, I note the reactions to the Halcro amps: some have praised them to the high heavens, others have considered them to have a sterile sound, whatever that means: I presume in the truth and tonality debate they figure heavily in the "truth" camp. Halcro may in fact have had subtle, audible faults, I can't say either way. Of course, any component that is truly low distortion will perfectly highlight, ruthlessly expose every distortion defect that exists elsewhere in the chain that makes up the audio system, rather than hide it under a soft cloak of "harmonic enhancement".

People will say that the recording is frequently badly distorted: yes, but the types of distortion there are at a far lower level of effective audibility if the replay system does its job properly. Once you've experienced what's possible, you realise that the talk of "bad" recordings is only that, talk ...

Frank

 

[fas42]

What about the Soulution amplifier that has received all around great reviews?

Thanks for mentioning them, Myles. I had looked them up, and was impressed with their intent and accomplishments, almost posted about it ...

Frank

 

[mep]

Tom-Can you name me a single modern tube preamp that uses 100% feedback?? I have been to 3 county fairs and two goat breedings and I have never heard this one before.

 

[MylesBAstor]

Well now, that feedback thing, now lets not forget that almost all tube pre-amps used (use) 100% feedback circuits. Feedback is your friend too.


And the 710 amp in above post most likely also uses 100% feedback circuits too. I did find it curious that they did not show an IM plot in their technical specifications....given superb conventional specs or as MEP seems to be harping on, measurments ( specs are results of measurments in my book and always have been IMO).

Tom

Not sure what type of feedback you're referring to but all cj preamps for at least the last 15 years (beginning with the Premier 7-the first dual mono preamp produced by cj) use zero global or local feedback. That includes my present day GAT.

http://conradjohnson.com/It_just_sounds_right/a-pr7.html