John Curl's Blowtorch preamplifier part II - Page 2748 - diyAudio
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Old 10th September 2012, 02:53 AM   #27471
morinix is offline morinix  United States
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Quote:
Originally Posted by hitsware View Post
Anyone here who has not written an article that made it to market
really is just blowing smoke.
I don't care how many circuits they have designed.
Oh gosh, feeling pain?
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Old 10th September 2012, 03:48 AM   #27472
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Wavebourn, please don't overreact to my comment. If YOU went to a local church or temple during services, and you behaved like many here do: Demanding that they PROVE the existence of whatever they believe in. You would be escorted out of the 'church' and if you resisted, the police might be called. However, you could NOT continually disrupt the service. You should know this. This Putin thing is political, not religious, I find it very sad that your country has such repressive laws.
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Old 10th September 2012, 04:09 AM   #27473
kevinkr is offline kevinkr  United States
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Please leave the political and religious metaphors out of the conversation going forward. Thanks...
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Old 10th September 2012, 04:21 AM   #27474
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To me the point is that this is a public forum about the subject of d.i.y. audio.

Many people who are new to the subject look at it for advice as to how to go about doing it and various technical matters to do with it.

To me it is incumbent upon anybody who makes a contribution to this to give the best technical advice that is known about the subject, and the assertion that you can hear such things that double blind testing shows that you can't, and this proves that such tests are invalid, is a thing believed in by only a small fringe in audio and has no technical or scientific validity, and people who want to know about the subject should be informed of this.

In the end there are some things that are just the what they are despite what you might believe about them, and science exists to find out what they are and how they might work.

In the end the recording and reproduction of sound is a technical exercise and has nothing to do with what you might believe, but has principles that keep on being what they are despite what you believe and my purpose is to state this fact and elucidate what they are, this is the only belief that I bring.
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Old 10th September 2012, 04:56 AM   #27475
AJT is offline AJT  Philippines
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you have good points there......

it is sad that those starting early in the diy hobby are the one easy to absorb audiophool notions such as cables, power cords and capacitors instead of learning how stuff works....
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Old 10th September 2012, 05:12 AM   #27476
fas42 is online now fas42  Australia
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Quote:
Originally Posted by rcw666 View Post
In the end there are some things that are just the what they are despite what you might believe about them, and science exists to find out what they are and how they might work.
A bit like the nature of the universe: at any point in time what's called science always understands how everything works, until some annoying individual or group of people drags some irritatingly contradictory evidence out of the woodwork. If only those unsavoury types would keep their ideas to themselves, then we could all be comfortable believing the earth was flat, and we are at the centre of the cosmos ..

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Old 10th September 2012, 05:18 AM   #27477
RNMarsh is offline RNMarsh  United States
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Default Old Info floating around --

There is a lot of old info floating around regarding what has been 'proven' to be audible. For example:

I did an informal test of my own distortion detection ability and found that below 0.1% was my limit - yet, I felt that lower levels could be detected if my own speakers werent masking the true threshold level. Well as far back as the Proceedings of the AES in 1990 (The Sound of Audio), research was reported on determining what the lower level was --

"The data indicate a distortion perception threshold of less than 0.05% at harmonics above the fourth for a listening level of 70 db." They too were limited by the system distortion as to what the threshold might really be for most people. So the threshold is even lower... .01% or less?

We know that the freq response in rooms have deep dips. "If the fundemental component of the signal falls in a response dip the effective distortion may be increased dramatically due to the reduction of the fundemental level." Many critical listeners will move thier head position while listening to hear these harmonics with a variety of music. Even listening in different places in the room, over time, can find the distortions in sound.

"Tool and Olive (1988) found that reverberation improved the ability to detect linear distortions (resonances) over anechoic listening if transients, such as speech, are used."

Lipshitz et al (1982) found a significant increase in audibility of phase distortion when listening with headphones instead of over loudspeakers. This is more relavent today with so many people listeing with ear buds, headphones.

The perceptual list about sound of audio goes on and on and here on this forum it is all glossed over and not even mentioned as if the body of knowledge is limited and cut-n-dried. Not even a qualification to a comment about what is heard or not under none dbx conditions. I guess it doesnt matter? A lot of science work has been done and published since the days of dbx testing. It isnt so clear cut to me anymore that one can make sweeping blanket statements about audibility.

Thx - RNMarsh

Last edited by RNMarsh; 10th September 2012 at 05:30 AM.
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Old 10th September 2012, 06:32 AM   #27478
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It is always interesting to go back 100 years or so, and really find out how discoveries were made, how many ideas were not given credence for many years. Yet, mathematics and logic was at a very high level then, just like today.
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Old 10th September 2012, 07:42 AM   #27479
jcx is offline jcx  United States
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it is a mistake not allowing for the exponential increasing amount of practical knowledge, associated increasing intensity of scrutiny the tech (including theory) gets as time advances, we rely on electronic tech more and more

today there are 4-5 ? orders of magnitude more people actively engaged in electronic design, measurement; making, using equipment also with many orders of magnitude greater resolution, speed, linearity in some dimensions than the situation 100 years ago

I always enjoy seeing posts about how little is known about electronic tech being posted by Luddites with GHz computers, Gbytes of ram, 10s-100s of billion transistors

how exactly do you think >1 MBaud DSL works over voice band twisted pair - I bet the wire to my home is >50 years old - yet we are assured, by audio Gurus, that Nyquist, Fourier theory "aren't complete, are misapplied", cables have mysterious properties "conventional engineering" has misssed


seems like too many of these proposed gaping holes in our limited understanding would have prevented much of electronic tech most take for granted



try comparing Marsh' "stretch" 0.01% estimate of distortion audibility to a $2 op amp - good order of magnitude margin almost any where above the < 2 kOhm noise resistance: (also note the CCIF, SMTE, and John's fav, Otala's DIM plots)
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Last edited by jcx; 10th September 2012 at 08:10 AM.
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Old 10th September 2012, 07:48 AM   #27480
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The point is that the findings science are not a thing that you can chisel in stone and regard as holy writ, but as they say science progresses when people die, and most who have made their name on a particular bit of it are very reluctant to admit that they were wrong and accept later findings that contradict their research.

This is because science is a human activity and those who do it are quite often all too human.

The fact is that for every wild eyed visionary who comes out of left field and revolutionizes every thing, there are millions of deluded ones who think they are that one, and of course plenty of cynical snake oil merchants exploiting the credulous, and of course especially in the later case, plenty of people willing to follow them if they are charismatic enough.

There is no doubt that there will be research that indicates different thresholds of distortion perception and it is also true that in western countries the hearing threshold in general has been increasing for quite some time since the world is now a very noisy place compared with former times, and if you pick a sample of young females from a quite third world country you will get a lower threshold than a population from a developed one, especially an older male sample, and I have no doubt that this sort of thing is done to skew findings in a particular way, it is certainly done in other fields.

But in the end however flawed science might be it's all we have if we want to find out what the world is really like rather than our subjective impressions of it.
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