Years ago I was spending some time in our shop trying to learn some metalworking, which had been given up after an unfortunate
high school shop project incident. I managed to make some progress, but also picked up some tinnitus in my right ear, a bit like an
(intermittent) 2kHz triangle wave sounds. After that I was much more careful, and gradually it went away. It does briefly return to a
lesser degree if I'm exposed to a loud noise, but then it goes away again.
Maybe similar to being in a flotation tank, sensory deprivation. I was once told about a guy who found God in a flotation tank, no kidding. As if that is where God has been hiding all this time? Very silly indeed.
Cheers, Joe
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I'd buy that as part of a general explanation for the even series arising in the output stage. The odd series I guess typically comes from the first stage diff amp. But why the even series is generally (always ?) significantly more pronounced ............?
Not at all, the circuit sketch is just a conventional NFB voltage amp, with part of the feedback network labelled 'current sense'. Sticking a label on it doesn't alter operation, the opamp operates conventionally - it is a voltage amp with NFB, conventionally loaded by the NFB network. Then how is using the virtual ground as a reference (rather than real ground) supposed to help with distortion .......?
Not only this, but the absence of early reflections of the noise we usually produce when we move+ the fact we walk in the vacuum on a fence, it can give vertigo or and loss of balance.
BTW: I was very disoriented, at the beginning of Digital, by the loss of the tape hisses. No more floor reference, that i used as ground on the top of witch i used to build my sonic landscapes.
I remember too, having being very uncomfortable to be unable to record any ambiance during the shooting of a documentary in the Moroccan desert. The cicadas and crickets usually go with the heat in the south of France. This dead silence was oppressive: Not the least "sound of silence".
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I was once told about a guy who found God in a flotation tank, no kidding. As if that is where God has been hiding all this time? Very silly indeed.
Cheers, Joe
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Some don't believe in NFB, others find God in a tank. It is a strange but beautiful world indeed.
Hi JC and the Gang --- typing from the land of the trashed country of Nepal..... Kathmandu this evening:
A couple thoughts --- when we are on high alert... like life is in danger, or when in a new invironment... all your senses are on full alert.... they seem to magnify our senses. I laid down in a dark anechoic chamber at U.C.Davis in California and after a few minutes I heard the rushing sound of blood in the ear moving with my heart beat. Others had done this and told me to try it and I found that same sensation they did..... it is like hearing is on high magnification.... ultra sensitive.
in a dead quiet room.
Also, I just finshed reading the LinearAudio edition on more capacitor tests. I noticed that with a dc bias, the 2H increased quit a bit. I reported the same thing but used an asymetrical waveform to produce the dc bias.
Weather is fine here.... nice in fact. Completely off my sleep schedule but only been here for the third day now. My adopted family came thru OK.
Very 3rd world here. If you can imagine what that is like.
THx-RNMarsh
A couple thoughts --- when we are on high alert... like life is in danger, or when in a new invironment... all your senses are on full alert.... they seem to magnify our senses. I laid down in a dark anechoic chamber at U.C.Davis in California and after a few minutes I heard the rushing sound of blood in the ear moving with my heart beat. Others had done this and told me to try it and I found that same sensation they did..... it is like hearing is on high magnification.... ultra sensitive.
in a dead quiet room.
Also, I just finshed reading the LinearAudio edition on more capacitor tests. I noticed that with a dc bias, the 2H increased quit a bit. I reported the same thing but used an asymetrical waveform to produce the dc bias.
Weather is fine here.... nice in fact. Completely off my sleep schedule but only been here for the third day now. My adopted family came thru OK.
Very 3rd world here. If you can imagine what that is like.
THx-RNMarsh
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Yes, I've spent quite a bit of time in anechoic chambers over the years - it's weird at first but perhaps like diving one just gets used to it. Not being able to hear well off-axis, especially when someone speaks or even the normal sound cues of walking about, it's pretty weird.
I understand that the blood rushing sound is, in fact, always there even in normal life. Just that we are used to it from birth, so it gets filtered by auditory part of yer brain. But, under duress, yer brain fails to provide this function. Same thing can happen under extreme types of other stress, one becoames aware of blood pounding in the ears.
I'm not sure that permanent tinnitus is ever 'normal', but I've always been surprised at the apparent prevalence amongst audiophiles on forums who suffer from hearing damage (rather than loss) of one sort or the other. By grace, I don't. But in an anechoic chamber, the auditory part of yer brain tries to guess or invent sounds, at least for a short time until one gets used to it. On the other hand I'd suppose it would expose permanent tinnitus, if present.
But, if one really wants to know what gear sounds like, anechoic listening is a frank and revealing to do. Speakers especially so.
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Right. I was surprised by the directivity of our ears, and how much our brain use early reflection to localize sound's sources.
Ooops, I mean virtual Vin, but you get the gist. Far as I can figure, it doesn't help distortion........
It's a very basic circuit of course, but the label 'current sense' throws you off. Did me.
Jan
Technics TTs
Agreed, the direct drive SP10's wow and flutter measure (and sound) lower than any belt drive I have ever measured. And this with less than 80mS typical time to speed lock! Of course they were supplied as a bare TT assy, and needed a separate isolation table and tonearm, making a full system big and expensive (relatively speaking...) I still maintain two in the Control Room of WXYC with only cap replacement every decade or so. The only TT with lower W&F I have measured was the direct drive Luxman 414/444 series. It's multi-gain step PLL gave outstanding speed accuracy at the expense of settling time (>5sec) and it's magnetic suspension gave extremely low rumble as well. It's needed assistance with vibration isolation, however...
When I would show Linn folks how high the W&F of their tables was they would cringe. I attribute the Linn's great sound to basically good enough speed accuracy, great platter bearing and excellent external vibration isolation, giving a very black background. To get isolation this good you need a separate dedicated isolation table for either the Technics or the Luxman. The Linn is a neat relatively inexpensive package!
Howie
Howard Hoyt
CE - WXYC-FM 89.3
UNC Chapel Hill, NC
Agreed, the direct drive SP10's wow and flutter measure (and sound) lower than any belt drive I have ever measured. And this with less than 80mS typical time to speed lock! Of course they were supplied as a bare TT assy, and needed a separate isolation table and tonearm, making a full system big and expensive (relatively speaking...) I still maintain two in the Control Room of WXYC with only cap replacement every decade or so. The only TT with lower W&F I have measured was the direct drive Luxman 414/444 series. It's multi-gain step PLL gave outstanding speed accuracy at the expense of settling time (>5sec) and it's magnetic suspension gave extremely low rumble as well. It's needed assistance with vibration isolation, however...
When I would show Linn folks how high the W&F of their tables was they would cringe. I attribute the Linn's great sound to basically good enough speed accuracy, great platter bearing and excellent external vibration isolation, giving a very black background. To get isolation this good you need a separate dedicated isolation table for either the Technics or the Luxman. The Linn is a neat relatively inexpensive package!
Howie
Howard Hoyt
CE - WXYC-FM 89.3
UNC Chapel Hill, NC
The quietness never bothered me.... I would lay down and rest and sleep in there.
The reason I was there in the first place was to measure speaker and measure a microphone on-off axis. Also to record the speaker with music and broadband noise to be played back later in a listening room with same speaker.
THx-RNMarsh
I have spent brief time in a true anechoic chamber (Dynaudio Struer factory 15years ago) and at first the experience is very strange.
Yes you can hear your own heart beat and blood flowing.
Self made vocal sounds and clicks/claps etc are completely foreign to normal experience with lack of room return echos or boom/resonance.
That said I did not find the experience at all disturbing, but instead comfortable and novel.
I live in the outskirts and my bedroom (and soundroom) is sonically very well damped and essentially silent and for me this is bliss...makes for great sleep.
Very interesting is to go into the Aus outback and at night is total sonic silence.....in contrast looking up into the skies is an altogether stunning experience.
Dan.
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