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Old 3rd Sep 2020, 4:35 pm   #1821
Craig Sawyers
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Default Re: The Audiophoolery Thread.

Ah - got it. It was EEG and PET scanning. Oohashi again...

Craig
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Old 3rd Sep 2020, 7:12 pm   #1822
knobtwiddler
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Ah - got it. It was EEG and PET scanning. Oohashi again...

Craig
Thank God they didn't use CT - I wouldn't want a decade's worth of radiation exposure just to find out my brain could sense tones over 20K...
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Old 3rd Sep 2020, 9:59 pm   #1823
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Default Re: The Audiophoolery Thread.

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Ah - got it. It was EEG and PET scanning. Oohashi again...

Craig
Thanks Craig, that is very interesting reading and certainly cause for some thought.

Steve.
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Old 3rd Sep 2020, 10:28 pm   #1824
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Quote:
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Ah - got it. It was EEG and PET scanning. Oohashi again...

Craig
Thank God they didn't use CT - I wouldn't want a decade's worth of radiation exposure just to find out my brain could sense tones over 20K...
PET itself is a radioactive imaging technique and you commonly get a higher dose from the PET than you would from X-ray CT of the same part of your body. To make matters worse they commonly do an X-ray CT at the same time as the PET scan to give them have a background map of the physical structure onto which they can overlay the bright and dark patches from the PET. So you end up with a total dose which Wikipedia describes as 'substantial'.

It's not unusual though for people who don't 'get' modern hi-fi, well, not to get it, and for people who do get it to be prepared to make significant sacrifices in pursuit of their hobby .

Cheers,

GJ
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Old 4th Sep 2020, 12:25 am   #1825
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Default Re: The Audiophoolery Thread.

I have seen claims that no-one else has been able to replicate Oohashi's findings and also that the effects are down to distortion in the high frequency drivers that he uses which produce artefacts below 20kHz. If the effect were real I would have expected other people to have written papers about it.

Unfortunately I can't find any really authoritative sources that disagree with him.
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Old 4th Sep 2020, 3:52 am   #1826
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Default Re: The Audiophoolery Thread.

There is plenty of audio being radiated in the region above 20kHz.... all those parking sensors on cars for example. Some SMPS are rather good emitters, too at a wider variety of frequencies. And then there's very high power from ultrasonic cleaning baths. So if people really were sensitive to these things, even if just a small section of the population, it would have been noticed.

I agree with James, maybe some intermodulation effect creating mixing products at normal audible frequencies is at work, due to some non-linearity? Or maybe it's all just wishful thinking, deliberate or innocent?

One thing is for sure, we have microphones and spectrum analysers that go into those frequency regions. A more interesting paper would be a survey of the >20kHz content in various live performances... acoustic ones, so we stick to original sound and don't get mislead into trying to reproduce the spurious oscillation or ringing of a bad stage amplifier. I'd expect cymbals and rimshots to have some content, maybe squeaks from wound strings.

There are two questions:

1) Is there any stuff to be heard?
2) Can anyone hear it?

David
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Old 4th Sep 2020, 11:57 am   #1827
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I agree with James, maybe some intermodulation effect creating mixing products at normal audible frequencies is at work, due to some non-linearity? Or maybe it's all just wishful thinking, deliberate or innocent?
I first came across the Oohashi study in the early 2000s when Internet groups were awash with debate. People were also citing Mr Neve's test where Geoff Emerick (Beatles' engineer) reportedly 'heard' 54KHz (there are plenty of articles / discussion about it if you search). My understanding then was that RN traced it back to ringing in an un-terminated transformer, thus creating IM artefact below 20Khz, exactly as you describe. I think the Oohashi / Emerick stories are quite interesting to research, not because they are peer-reviewed and repeatable, but more for audio-types' response to them.
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Old 5th Sep 2020, 12:34 am   #1828
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1) Is there any stuff to be heard?
To answer your question - if I use a spectrum analyser on files of tapes I've transferred at a sampling rate of 96kHz I can often see things going on above 20kHz. Certainly cymbals produce these frequencies but synthesisers can also produce high levels above 20kHz. There is also plenty of unwanted information above 20kHz - probably from video monitors or other kit that no-one thought to check at the time.
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Old 5th Sep 2020, 3:04 am   #1829
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Default Re: The Audiophoolery Thread.

I take 20 kHz to be a rough approximation of the absolute highest frequency a human can hear (in my high school physics text it was 16 kHz) but in practice it can be much lower, depending on age, sex, hearing loss, wax and dirt in the ear canal, etc.

I worked for a time in the hearing aid industry which is mostly geared towards helping people understand speech. We tested peoples' hearing often to no higher than 8 kHz. Many of the school audiometers I calibrated in the summer holidays could test no higher than 6 kHz. Many older clients had a severe drop in response above 1 kHz. If we could help them restore some clarity from above 1 kHz to 3 kHz it made a huge difference to their lives especially in conversations. The range from about 300 Hz to 3 kHz is where much of the action is.

When I see people arguing over whether this speaker is better than that because it goes out to 23.5 kHz as against the other's 18 kHz, I wonder if they have had their own hearing tested lately. What can they actually hear?

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Old 5th Sep 2020, 12:25 pm   #1830
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Default Re: The Audiophoolery Thread.

I have a hearing aid, two in fact, but only really need it for speech. It really helps with that, but maybe surprisingly it doesn't make anywhere near as much difference to music. I put it down to music having a "flywheel" effect, I subconsciously fill in and don't really notice. Speech is different, it's all too easy to lose sync!
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Old 5th Sep 2020, 1:13 pm   #1831
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Default Re: The Audiophoolery Thread.

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There are two questions:

1) Is there any stuff to be heard?
2) Can anyone hear it?

David
I agree, there's more work needed and the results (whatever they are) would certainly put paid to a lot of speculation.

Steve.
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Old 5th Sep 2020, 2:05 pm   #1832
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I take 20 kHz to be a rough approximation of the absolute highest frequency a human can hear (in my high school physics text it was 16 kHz) but in practice it can be much lower, depending on age, sex, hearing loss, wax and dirt in the ear canal, etc.

I worked for a time in the hearing aid industry which is mostly geared towards helping people understand speech. We tested peoples' hearing often to no higher than 8 kHz. Many of the school audiometers I calibrated in the summer holidays could test no higher than 6 kHz. Many older clients had a severe drop in response above 1 kHz. If we could help them restore some clarity from above 1 kHz to 3 kHz it made a huge difference to their lives especially in conversations. The range from about 300 Hz to 3 kHz is where much of the action is.

When I see people arguing over whether this speaker is better than that because it goes out to 23.5 kHz as against the other's 18 kHz, I wonder if they have had their own hearing tested lately. What can they actually hear?
According to a great audio designer that I used to chat with, when he was working for Harman around the early 90s, the company insisted that reviewers could only get priority access to the latest kit if they got an audiogram. He said that the results were mind boggling, in that some of the ones most interested in cables and the like had totally odd hearing. If you really are passionate about music, then you're likely to have been to more than a few gigs in your time. If you've forgotten your earplugs a few times, by the time you're over 50, genetics aside, you're highly likely to know about it (a doctor told me that people who live in rural areas consistently show better hearing responses than those based in the city - I've never researched this, but it's believable). In short, they found that those often obsessed with items on the periphery of what's known to be audible, often had the strangest looking audiograms...

The hearing mechanism is in a constant state of flux. It has numerous mechanisms (Malleus, Stapedius, Cilia etc) that can attenuate levels, which vary by tiredness, nutrition, mental state and other factors. Even if you have perfect hearing, it will never the *exactly* the same from hour to hour, particularly if you've come into work on the Tube and had a lot of coffee (for example). One could argue that the whole concept of publishing subjective listening evaluation to be so unscientific, it verges on the pointless (approaching immoral, if you consider that livelihoods depend on reviews in a competitive marketplace).
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Old 5th Sep 2020, 2:18 pm   #1833
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... One could argue that the whole concept of publishing subjective listening evaluation to be so unscientific, it verges on the pointless ...
Perhaps there is some worth though in a single reviewer's comparative reporting - e.g. "I found speaker A to be more open and transparent, albeit with a poorer bass response compared with speaker B which could deliver the low organ notes but at the expense of sounding 'boxy' at higher frequencies", or if you've been following a particular reviewer for a while and have found that your likes and dislikes match theirs, or are the exact opposite ?

In the end though, as has been said many times already, there's nothing like hearing equipment yourself, ideally in your own listening room.

Cheers,

GJ
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Old 5th Sep 2020, 3:58 pm   #1834
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...the results were mind boggling, in that some of the ones most interested in cables and the like had totally odd hearing.
I had the job of "doing the bones" for a self-styled star remastering engineer once - the number of new innovations he hailed as night and day improvements at fortnightly intervals beggars belief. And once he chucked a perfectly good Technics SP10 in the bin because it was direct drive and of course they ruin the music...you had to speak up on the 'phone, mind.
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Old 5th Sep 2020, 4:22 pm   #1835
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Default Re: The Audiophoolery Thread.

We have a saying, "Nowt so queer as folk"
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Old 5th Sep 2020, 8:03 pm   #1836
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...the results were mind boggling, in that some of the ones most interested in cables and the like had totally odd hearing.
I had the job of "doing the bones" for a self-styled star remastering engineer once - the number of new innovations he hailed as night and day improvements at fortnightly intervals beggars belief. And once he chucked a perfectly good Technics SP10 in the bin because it was direct drive and of course they ruin the music...you had to speak up on the 'phone, mind.
As you will know well, a lot of reissues are coming not from original tapes, but the earliest vinyl editions that the reissuer can find. They are then archived to digital, whereupon their origins are disguised with the use of filters (de-rumble), and de-clicking SW. On 2 occasions in the last year, a star mastering engineer has accused a preamp I designed (used to transcribe) of inverting the phase. This has happened with 2 different owners who've reissued rarities (much as I adore vinyl, in this case I'd rather get the digital release - I don't see the point in having a reissue with double the THD+N etc). As a star ME people listen to him, obviously (his rates are about double your average ME).

How can he tell absolute phase has been flipped on a rare piece of vinyl made in Uganda in 1973 with nothing to compare it against? Secondly, the preamp is a non-inverting design...(it has minimal phase shift, and uses 0.1% Rs and 1% Cs). I was going to call him to discuss this, as it isn't good for my rep. But I didn't, as I'm wondering if he is so deeply into phool ideology that I'm probably banging my head against a brick wall...

This reminds me of 2 occasions about 25 yrs back when I was engineering in studios. Separate clients saw that the cables connecting the DAT player looked cheap and refused to listen through them. I whipped out a couple of nicer looking XLR cables, plugged them into redundant sockets and put the music back on, but with about a dB increase. 'Thank you, that sounds much better'...
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Old 5th Sep 2020, 8:07 pm   #1837
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NB - I hope you snuck around to the bins and rescued the SP10
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Old 7th Sep 2020, 12:29 am   #1838
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Default Re: The Audiophoolery Thread.

Good day Gentlemen,

Thank You ! for a great education about the topic, i've read all 92 pages over the last 6 months.

I hope you enjoy the review about this 350K$ class A Amp using an RF power tube.
Nice construction though, and at +/- 800lb weight, probably better to live on the ground floor.

https://www.stereophile.com/tubepowe...vac/index.html

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Old 7th Sep 2020, 7:18 am   #1839
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Default Re: The Audiophoolery Thread.

Thank you, jhalphen! That is truly in the spirit of the audiophoolery thread.

What seems to be missing in that review, after pouring so much praise over that amplifier, is any announcement that he had bought a pair. How can he now live without them having had such an experience?

But if that amplifier is so wonderful, so transparent, then maybe what he was reviewing was not the sound of the amplifier, but the acoustic signature of his power provider and all the cabling and transformers en-route to his home?

The specification section of the review alone is worth a good laugh. The dimensions and weights are given quite comprehensively, but the output power is specified without mentioning the distortion level at which it applies, similarly the frequency response values do not state at what level of roll-off they apply. So the figures relating to it being an amplifier are just guff.

I also think this sort of review could only be written by someone blissfully unaware of how unfashionable was the gear the recordings were made with.

What it has done is made me realise that the amplifier in my lounge was installed and set-up by its designer in person. All these years I've listened to something with such an advantage and I'd never noticed it! I must be deaf.

David
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Old 7th Sep 2020, 8:53 am   #1840
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... The specification section of the review alone is worth a good laugh. The dimensions and weights are given quite comprehensively, but the output power is specified without mentioning the distortion level at which it applies, similarly the frequency response values do not state at what level of roll-off they apply. So the figures relating to it being an amplifier are just guff ...
I hardly ever read hi-fi mag reviews of what an amp sounds like. But Stereophile, where this one appears, has the huge asset from my point of view that the very last page consists of actual measurements carried out by John Atkinson. John seems to be 'old school'. He takes care over the numbers. He has no problem with disagreeing with the 'I just listened to it' reviewer, who's written the other five pages. As far as the power spec goes he writes

So, what about the SH-833's output capability power? Those 550 lbs and that humongous transmitter tube promise a lot of power, not to mention the specified "effective" output of 150W. As you can see from figs.5 and 6, which plot the percentage of distortion and noise in the Wavac's output against power from the 8 and 4 ohm taps, respectively, that promise is not kept. At our usual definition of clipping—1% THD+noise—the Wavac gives out just 2W or less into loads ranging from twice the nominal tap impedance to one quarter that nominal value. The highest power is obtained when the load is half the nominal tap—ie, from the 8 ohm tap into 4 ohms—but even then, the definition of clipping has to be relaxed from 1% to 10% for the amplifier to approach its specified power. Looking at the waveform on an oscilloscope during these tests, the point in these graphs when the waveform clips is actually the sharp notch in the traces. At 10% THD, the amplifier is putting out a pretty good squarewave!

and in conclusion

So, that's that for the Wavac SH-833. I can't explain why Michael found its sound so seductive; all I can do is point to the measurable problems or audible idiosyncrasies that must be listened through to hear what it does right.


Good man.

Cheers,

GJ
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