[VYnuhl.Addict]

Hi Hugh,


    I agree with your ideals on the Harmonic distribution as a waterfall on paper, monotonically decreasing, but if I may add, I think just as important as this is, its also important that this also be consistent across the Audio band(in its order, and quantity) from 20hz to 20khz. As we know, most amplifiers have immeasureable distortion at 100hz and up to 1khz, and after this 1khz area it dramatically increases hence why most amplifiers only give an averaged 1khz measurement. This seems to have a profound effect on the sonic relationship, just as profound as the Monotonically decreasing  factor..





Colin

[James Romeyn]

Domestic rooms seem to affect music in completely different ways above 200 Hz compared to below 200 Hz.  The difference is so dramatic that I have concluded that any so-called "full range" speaker is permanently flawed except for one huge and prohibitively expensive exception.  To the extent this is true the state of the art is a bi-amp speaker with one section for music below approximately 200 Hz and another section for music above approximately 200 Hz. 

IMO Geddes, Welti, and Duke LeJeune have well-proven both theoretically and performance wise, the single best technology to reproduce music below 200 Hz is a distributed multi-sub array.

There are so many variables in taste for musical qualities above 200 Hz that it appears futile (or worse) to attempt to pick an overall winner in speakers for this range, though I have my own distinct hierarchy of preferred attributes.     

I think the above philosophy works well with good amp design.  Meaning: comparatively high-powered digital amps may be preferred below approximately 200 Hz for low heat, low initial cost, and low power draw (soon a legal mandate almost certainly), but it is extremely important and often difficult to get the right mix of performance attributes above 200 Hz.  (It's also easier to smooth a speaker's impedance peak above the bass range than below.  The smoother a speaker's impedance load the easier it is to make its associated power amp sing great music.  This is just another reason to split the entire music system below and above the bass range.)     

I make no apology for the fact that the above philosophy is anathema to many or most hobbyists.     

[Tyson]

Or you could go active, using something like a DEQX.  In my room, 200hz is too high, and below 80hz is too low for my midrange/bass crossover.  150hz is just right, allowing me to deal with a room induced mode right in that area, without needing a bunch of EQ. 

[AKSA]

Hi Colin,

The reason most amp manufacturers don't publish results at 20KHz is because they are so bad!!  I think vindicates your position very strongly.....

James, rooms are vital, couldn't agree more.  I have a door three feet to the left of my left speaker.  If the door is ajar, the sound and image are completely different, even though the listening chair is centrally placed!

Loved the crack about McCartney!

Tyson, welcome back!  I have my doubts about introducing even more electronics into the chain.  I have a customer bought a DEQX, and the agony of choice eventually got to him.  He no longer uses it, unfortunately, a wasted resource.

Cheers,

Hugh

[bhobba]

I have a customer bought a DEQX, and the agony of choice eventually got to him.  He no longer uses it, unfortunately, a wasted resource.

I too went through a phase where I was very keen on a DEQX.  It probably is the way of the future - but right now it has some issues and because of that I eventually went cold on it.  I have talked about it to two very knowledgeable speaker designers and the skinny is - wait for it - conventional crossovers sound better. They are not only cheaper - but sound better - especially if you use top of the line components like mundorf capacitors and hand wound air core inductors - but even if you dont it still is better.

To do it properly you need to room correct both phase and frequency and for that you need massively more processing power.  It corrects crossover phase - but not room phase errors.  That will eventually come - but right now it's not there.  And the DEQX DACs are not the last word - they are getting better - but still have a way to go.  Again that will come but time is needed for the price to drop to have the best DAC's on all channels. 

Thanks
Bill

[Joe Rasmussen]

...DIYaudio forum and been pilloried by some of the smartest guys in the room.   It is difficult to discuss things with these guys as they really are frightfully intelligent, and have formed a very negative judgment well in advance... 

Don't I know!!!

Not long ago I asked a question on one guy's forum (he certainly treated it like it was his) that could have been answered by a simple yes or no. What I got was a lecture based on something I was supposed to have said earlier and actually hadn't (he never went back and checked the facts). I thought it only right to correct him as I didn't deserve that serve. No apology. When I re-asked the original question and requested the answer this time being just yes or no, boy did I cop some more. BTW, the answer was yes and he could have said so but never did. At all times I was being as cordial as one could be.

I know that Terry was monitoring this, so I gave him a call. Terry too reckoned so-and-so did go too far and added something along the lines that he "owned" that forum or treated it as such. I was encroaching? Nobody should treat a forum as a pulpit, no matter what the temptation is.

I have happily dealt with some of the brightest people one can meet and it has struck me that the brightest are also of humble minds. To quote Niels Bohr, Einstein favourite sparring partner and extremely close friend, when asked what made a person an expert, he thoughtfully said: "An expert is a man who has made all the mistakes which can be made in a very narrow field." He also said: "Every valuable human being must be a radical and a rebel, for what he must aim at is to make things better than they are." No high-mindedness there.

For those interested in more Niels Bohr quotes: http://en.wikiquote.org/wiki/Niels_Bohr - there are some beauties!

Bridging?  Nah.....  I don't recommend it, because along with the increased power comes double the current, and this must pass through the same output stage at both ends of the waveform...

Not surprised. Yeah, you are right, as active devices both ends in series you have to dissipate twice the heat for the same current.

The NAKSA output stage is pushed hard, with a single pair on 42V rails, and to effectively bridge it you would need two pairs on each amp.  The best and most economical option would be to simply build out the output stage on a NAKSA and increase the rail voltage...

Or bi-amp - I've liked the results doing that in the past.

Cheers, Joe

[James Romeyn]

...Nobody should treat a forum as a pulpit, no matter what the temptation is....


Cheers, Joe

Joe
I thoroughly enjoyed your entire post, especially the quotes.  Please excuse my quoting only one little part, which I found especially enticing. 

I've read much about the history of the so-called church, or what is more aptly described by the great author/researcher Michael Hoffman as "churchianity".  There is good documentation that the pulpit itself has absolutely no basis in the scriptures.  In other words, some well-researched theologians could and do argue quite well for the banishment of the "pulpit" you mention, even from the gathering of believers!  If it doesn't belong there (and I'm convinced it certainly does not), how much less does it belong in an audio forum?   

Please forgive my OT adventure, and continue with the previous dialog, which it appears we are all enjoying very much!

 

[Joe Rasmussen]

Joe
I thoroughly enjoyed your entire post, especially the quotes.  Please excuse my quoting only one little part, which I found especially enticing. 

I've read much about the history of the so-called church, or what is more aptly described by the great author/researcher Michael Hoffman as "churchianity".  There is good documentation that the pulpit itself has absolutely no basis in the scriptures...

I've got to tell you, I am big on the Bible and have an enormous respect for it. Many use quotes in daily life and don't even know it comes from the Bible. There are parts in it that transcends any human philosophy. But I suspect if I start saying anything, there would be attempts to put me in a box. Instant judgements abound. For example, have you noted how may audiophiles are often frustrated reviewers, and that is by barely listening for more than a few minutes (how do they do that?). I make it plain I am not an instant reviewer, I'm not even a reviewer at all, more like a fellow traveller looking at the same scenery. Do you like it? Yes? Good, me too. That's all.

So when I speak re the Bible and Christianity (and Judaism) etc, I need to find the correct forum. But I avoid using the language, whether on audiophile or Bible matters, that 1) makes it easy to put into a box of their making and 2) avoids false piety and a preachy tone. You can preach but don't be preachy. Preach rhymes with teach - and that is OK. Preachy, don't know what it rhymes with, but who cares? 

The biggest conspiracy theory of all? God is actually looking???

Cheers, Joe

[Afterimage]

While the Bible may have many universal truths, a literal interpretation can be dangerous and limiting IMO.   

[James Romeyn]

I apologize for taking the hard OT turn.  My only intent was to take notice that that the pulpit has only human origin and is without a "holy" origin...hence, if it does not belong even in "churchianity" it is even less appropriate in an audio or any other forum.  But I suppose I better get off my "pulpit" ASAP!

I'm under the distinct impression that the best teachers in university are ones who foster questions and instill in their students as much curiosity as possible.  My wife and I were privately tutored by USU English Department Professor Emeritus Gene Washington (descendant of George).  It was almost impossible to know where he stood on most subjects, except that he loves "absurd" stories, movies and plays (as would most frequently-published authors of absurd works). 

Gene suggested and we recently enjoyed the "absurd" Gene Wilder/Zero Mostel movie "Rhinoceros".   

[Joe Rasmussen]

While the Bible may have many universal truths, a literal interpretation can be dangerous and limiting IMO.

Depends on what you mean by a "literal interpretation"?  Even that is limiting the discussion, if we were to have one here, but perhaps not the right place. A parable (and there are quite a few) are not literal, but they illustrate and teach an essential point, whether truth or a moral lesson of some kind. Taking a parable literal would be pointless, right? And then miss the point entirely at the same time. No, it is context that rules.

Try to explain literally the sound of an oboe. I defy your capability to do that. Literalness sets limits that are neither wise nor practical.

Cheers, Joe

[Afterimage]

Yes Joe, I think I agree with you.  What I meant is the lessons from the parables are the important stuff and other things in it such as how old  the Bible says the earth is not so much.  Again, like you said, context. 

[gaetan8888]

Depends on what you mean by a "literal interpretation"?  Even that is limiting the discussion, if we were to have one here, but perhaps not the right place. A parable (and there are quite a few) are not literal, but they illustrate and teach an essential point, whether truth or a moral lesson of some kind. Taking a parable literal would be pointless, right? And then miss the point entirely at the same time. No, it is context that rules.

Try to explain literally the sound of an oboe. I defy your capability to do that. Literalness sets limits that are neither wise nor practical.

Cheers, Joe

Hello Joe

I've found that learning some archeology and Biblical history give me an easyer understanding of the contexts wen I read a Bible text, context give a good way to see where it's to be readed as literal or not.

Btw Joe, wen I was living in Montreal and doing astronomy in the 80's, there was a man name Rasmussen who was working in aeronautic and doing small machining and electronics job for our Dorval astronomy club. Is it somebody of your family (maby a cousin in Canada) ?

Thank

Bye

Gaetan

[gaetan8888]

Hi Hugh,


    I agree with your ideals on the Harmonic distribution as a waterfall on paper, monotonically decreasing, but if I may add, I think just as important as this is, its also important that this also be consistent across the Audio band(in its order, and quantity) from 20hz to 20khz. As we know, most amplifiers have immeasureable distortion at 100hz and up to 1khz, and after this 1khz area it dramatically increases hence why most amplifiers only give an averaged 1khz measurement. This seems to have a profound effect on the sonic relationship, just as profound as the Monotonically decreasing  factor..

Colin

Hello Colin

Yes, thd measurements and thd spectrums of amps are usefull but don't say all about an amp.

I remember seeing 10khz thd spectrums of two amps, both spectrums was similars but the sounds qualities was very differents, for now we seem to be quite limited with the actual measurements technics since our ear detect things that even a AP equipments will not see at all.

Btw, IM measurements are only done with two signals, maby doing it with more signals with a spectrum analysis could show a bit more about an amp. Music do have so much more signals that it could change the beaviour or an amp compared to a sine or two sines tests.

Bye

Gaetan

[VYnuhl.Addict]

 
Hi Gaetan,

   I agree, Thd is not really that useful, the spectrum is I believe, but more importantly ive found feedback must also be scrupulously, carefully used to acheieve not Low distortion, but!, more of an even handed approach. its common knowledge that excessive feedback will lower distortion but the more there is, and being limited by stability margins, phase shift, and the need to drive a reactive load this feedback becomes less and less useful at HF with increased db levels..  Two amps sounding different yet measuring the same is most common, there are plenty of variables which we are all trying to figure out and explain and this is  what keeps us always trying to build a better mousetrap, the only way this can be done is to build and listen. The ear is more sensitive than any device on any day, the best way to measure I strongly feel and fully agree with you on that one, but this is also a comment that would have me lambasted by the Engineers, oh well ..


Colin


 

[Joe Rasmussen]

Btw Joe, wen I was living in Montreal and doing astronomy in the 80's, there was a man name Rasmussen who was working in aeronautic and doing small machining and electronics job for our Dorval astronomy club. Is it somebody of your family (maby a cousin in Canada) ?

Gaetan

Hi Gaetan

No relation. It is a common Danish name and one of the ten most common names in Denmark. The last three Prime Ministers there, including the current one, have been named Rasmussen. In Sydney alone there are about 70 listings in the local phone book - none are related.

Here is a really strange one: At 9/11 there is a Robert Rasmussen on the list of those who died in the Twin Towers and also on the same day a Rhonda Rasmussen who died in the Pentagon attack. Very curious, they even shared the same initials. Could have taken some amazing odds on that one.

So my name doesn't sound all that common, but it is.

Cheers, Joe

[gaetan8888]

Hi Gaetan,

   I agree, Thd is not really that useful, the spectrum is I believe, but more importantly ive found feedback must also be scrupulously, carefully used to achieve not Low distortion, but!, more of an even handed approach. its common knowledge that excessive feedback will lower distortion but the more there is, and being limited by stability margins, phase shift, and the need to drive a reactive load this feedback becomes less and less useful at HF with increased db levels..   
Colin

Hello Colin

Wen I was sim and prototyping my last amp, and chating with Hugh about it, I was obsessed by reaching very low lf and hf distortions with a nice thd spectrum, my amp was excellent sounding.

But after few thinkering I've decided to lowered a lot my gnfb ratio for a lower feedback in my prototype, giving a close loop gain of arround 40 db, the sound became better, more alive and more define. The thd spectrum was not very different but the sound was different.

I was aware about the effects of medium to high feeback on the sound but I did not take it seriouselly enough.

Most modern amps, including very costly commercial amps, use very complex topologies with high feeback giving very nice measurement but a bit lifeless and ordinary sound.

There is some thread in the other forum where some "brains" talk about their amps going down to .0000something% thd, and all the guys giving them high praise. But none of them did listened to those amps.

Bye

gaetan

[AKSA]

Hey Joe (remember that line from Jimmy Hendix?)

Your name is indeed seen frequently, and I might posit that it's the Danish equivalent of Smith in English?  Much more colorful and good sounding than Smith, however....

James,

Ah, Churchianity, I love it.  We have it in Oz too, and it's BIG BUSINESS, preaching that wealth and ostentation is God's reward to a hard working, entrepreneurial flock.  Speaking very personally and definitely OT, I believe that there is a strong need for many of us to seek meaning in the existence of a Greater Being.  That there are so many deities, each worshipped with equivalent zeal and conviction, leads one to the notion of spiritual opiate, a Stairway to Heaven if you will, and the tenet of unsubstantiated faith.  This takes us back to Karl Marx, was it, opium of the masses?  Or is that FIFA, and its clarion horn, the Vuvuzela?

This is not to ridicule anyone, but simply to make the observation that we all exist in the physical, the intellectual and the spiritual plane and we seek self-actualisation.  Everyone's vision of this path is different, and be grateful it is.  I think Man is always looking for ideas to which he can hitch his star, and for which often he will fight to the death.  The most recent has been the failed 70 year social experiment which crashed in 1989 - a great concept, but not the answer.  And we might be concerned that the GFC of 2008 and again this year is not the answer either, but it does cater rather better to self-interest, clearly a fundamental aspect of self-actualisation, ignored at risk.

Colin, Gaetan,

My thoughts are that THD is but one part of it.  We can add gain stages to an amp and using global negative feedback bring back THD to 0.0005% or even better.  But, as I think we've all observed, the music doesn't get any better, it seems to lose vitality and turns 'grey', delivering a mechanical rendition which lacks engagement.  Subjectivism and 'golden ears' need a better rap, they really do, and if by reducing GNFB we improve the sound whilst simultaneously increasing THD, then it might be that the conventional approach is a grossly flawed paradigm.

I suspect that the real problem is the speaker.  It is not a passive load, it is a violently active load, and it affects the amp seriously.

Hugh

[Afterimage]

Good insightful post Hugh.  Speaking of the social experiment, I was behind the iron curtain for about a month in 1985.  Took a train from Helsinki to Moscow.  Before leaving we were told to ship anything western back home as it was not allowed.  Stuff like music and magazines ect... We didn't.  At the boarder the Russian soldiers came on the train with their AK 47s and started digging through our luggage.  I thought they were going to take our stuff away because it was illegal.  Nope, one soldier just went through my cassette tapes and took all the Beatles albums that he did not have yet.  He told me I about completed his collection and let me keep pretty much anything him or his guys were not interested in.   When in Moscow, oh my, capitalism was alive and well.  It was in the form of a black market but it was thriving.  The stuff we brought in that got past the soldiers was good trade material.  By the way, if anyone ever has a chance to travel that way, you have to see St Petersburg.  A beautiful City. 

[PJR]

  Hi all. The following link should take you to a top view of a fully assembled NAKSA 70, mounted in an Altronics 2U extra deep vented case. http://www.audiocircle.com/index.php?action=gallery;area=browse;album=3557
Having recently assembled 10 modules for Hugh, my comments are perhaps a bit biased. But for what its worth, I find that this little amp is outrageously good for its size and cost. It is significantly better at such things as inner detail, imaging, depth and slam than my LF100 Mk ll. I'm quite baffled about how this can happen with a greatly reduced component count vs the Lifeforce, but there you are. I predict that many who buy the NAKSA 70 as a budget amp to drive to drive their second string system will find it very difficult to justify to themselves (not to mention their better halves!) why they have previously spent up to 5 times as much on a power amplifier. Its that good!!

I fired up mine for the first time last night, listening to a diverse range of performers such as Charlie Rouse, Billie Holliday, John Coltrane, Johnny Hartman, Mel Torme, Norma Waterson, the incomparable June Tabor, and the exceedingly lovely Katherine Jenkins. Even with the wick turned to the max on a ESP P88 AD826-based preamp - with signals coming from a Sony SCD940 SACD (upgraded to VS Level 7 by Joe Rasmussen) - the sounds emitted by the VSonics were by far the best I've ever heard from any one of my home systems during the past 30-odd years.   

Regards, Peter Roberts