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ARSCLIST  November 2015

ARSCLIST November 2015

Subject:

Re: What is really higher resolution?

From:

Dave Burnham <[log in to unmask]>

Reply-To:

Association for Recorded Sound Discussion List <[log in to unmask]>

Date:

Tue, 24 Nov 2015 02:54:46 -0500

Content-Type:

text/plain

Parts/Attachments:

Parts/Attachments

text/plain (376 lines)

John Haley was of course the person who posted the information several months ago that I referred to. Even when I could hear frequencies >20 kHz, I certainly couldn't hear any pitch, nor, I think, can anyone else. 

db

Sent from my iPhone

> On Nov 24, 2015, at 2:16 AM, John Haley <[log in to unmask]> wrote:
> 
> It may be a fifth, but it's a fifth that is something like two octaves or
> so above the top of the piano keyboard, starting to be dog-land up there.
> We need those octaves for the overtones, but they are quite soft way up
> there, compared to louder fundamental tones and lower overtones going on in
> normal hearing range.  I'm all for reproducing the overtones, at least
> those we can hear, but the loss of them that far up will be a very subtle
> difference when it comes to experiencing music, and an inaudible difference
> to many people anyway.
> 
> Back to the original topic, I just dubbed several brand new sealed LP's,
> recently pressed on "heavy" vinyl (they are reissues of 1960 LP's),
> digitizing them at 96/24 and then messing with them in Izotope RX4.  My
> 96/24 dubs sound *exactly* like the LPs themselves.  I am reminded how
> essentially inferior the LP medium is, when given the kind of scrutiny I
> have just been giving it.  Of course I am using excellent quality playback
> equipment to play the records, and that equipment sounds quite wonderful.
> Looking at the result on the computer, we get a lot of very low frequency
> grunge that is pure groove noise, and even these sealed records are
> yielding way too many clicks and pops, that I have had to remove, even tho
> I cleaned the new records diligently with a soft brush, right before
> dubbing them.  The groove noise higher up is occasionally distressing,
> being worse in one channel (I am removing most of it), and the kicker is
> that not a single one of these new records is perfectly centered, with
> respect to the center hole.  You an hear that!  I am getting excellent
> sound from some of the LP's, after I fix all the problems generated by the
> LP medium itself, but some of them have an unpleasant glaring midrange that
> just sounds like, well, an LP record, as opposed to an all digital
> recording.  Granted that there are audio engineering decisions that existed
> before the record was made that may account for some of this, but I keep
> thinking that pressing imperfections in the LP itself are part of that
> problem too, as nobody but a fool would create a master tape today that
> sounds like this.  It has taken me several hours per record to bring them
> "up to stuff," so I can really enjoy listening to them without regretting
> the format, and of course the LPs are never going to sound this good again
> after subsequent playings.  Bottom line, for me it is really absurd to get
> reissued classic recordings pressed on vinyl.  This is just a silly trend.
> These recordings should have been reissued in some hi-def digital format,
> where they would not have suffered the indignities of being put through an
> obsolete, superseded, old-timey format.  Phooey on brand new vinyl!
> 
> I think trying to figure out if the analog recording process is losing more
> data than a digital format is dancing on the head of a pin.  In the real
> world, there are far larger basic performance issues are vastly more
> important.  LP records became obsolete for some very good reasons.
> 
> Best,
> John Haley
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> On Mon, Nov 23, 2015 at 6:00 PM, Ellis Burman <[log in to unmask]>
> wrote:
> 
>> 14K is an A and 21K is an E, so it's a 5th.
>> 
>> Ellis
>> 
>>> On Mon, Nov 23, 2015 at 2:25 PM, Dave Burnham <[log in to unmask]> wrote:
>>> 
>>> When I was born, (1942), we didn't even have 78s; we only had records. If
>>> you had gone into a record store and asked if they sold 78s, they
>> probably
>>> would just looked at you blankly; that all changed in 1948 when LPs were
>>> introduced.
>>> 
>>> In spite of the gifted hearing that my friends and family give me credit
>>> for having, I, of course, have never HEARD bias except as I described
>> when
>>> "rocking" tape at slow speed. So it's probably a non-issue. Now,
>> naturally,
>>> my hearing is not near as good as it was when I was younger, but I was
>>> encouraged by a comment posted here several months ago that the
>> difference
>>> between the 21k I could once here and the 14k I may be able to hear now
>> is
>>> only a few notes of the scale.
>>> 
>>> db
>>> 
>>> Sent from my iPhone
>>> 
>>>> On Nov 23, 2015, at 11:37 AM, Tom Fine <[log in to unmask]>
>>> wrote:
>>>> 
>>>> Hi Dave:
>>>> 
>>>> 1. most if not all professional tape machines had a "bias trap"
>>> (low-pass filter) to block bias interfering with playback. Keep in mind
>>> that early tape recorders, and especially early magnetic film recorders,
>>> had relatively low bias frequencies (several well under 100kHz), which
>>> could beat with some audible frequencies. So the bias trap was an early
>>> known thing in magnetic recorder design.
>>>> 
>>>> 2. in the case of a Plangent transfer, a separate electronics path
>>> recovers bias, onto a separate digital track. The audio tracks do not
>> have
>>> any bias interaction or "pollution." John Chester can explain this in
>>> better detail, since he built the electronics.
>>>> 
>>>> Also, I agree very much with John Chester's point that the digital
>>> "recording" system must introduce as few distortions or errors or
>> anything
>>> else as is technically possible, because all of that compounds on the
>>> playback errors from the analog source. One thing we haven't discussed is
>>> that there are many different ADC designs, some offering a more
>> transparent
>>> analog front end and also some being better able to deal with peak-levels
>>> from the source than others (ie analog headroom --  you certainly don't
>>> want overload distortion to happen before something is digitized). The
>>> thing that  I find very impressive about the march of knowledge and
>>> technology is that we have these kinds of tools today, at affordable
>>> prices. This has all happened in my lifetime. When I was born (1966), NHK
>>> had not yet developed a reasonable-fidelity digital audio recorder.
>>>> 
>>>> -- Tom Fine
>>>> 
>>>> ----- Original Message ----- From: "DAVID BURNHAM" <
>> [log in to unmask]>
>>>> To: <[log in to unmask]>
>>>> Sent: Monday, November 23, 2015 10:50 AM
>>>> Subject: Re: [ARSCLIST] What is really higher resolution?
>>>> 
>>>> 
>>>> Well also, (and I haven't read about this anywhere but it seems
>>> plausible), the analog signal on a reel to reel tape is riding on a high
>>> frequency bias. This bias signal is on the tape as an audio signal,
>>> (plainly heard if you are "rocking" the tape across the head at a very
>> slow
>>> speed. If you're sampling at 196khz, I can visualize some interference
>>> between the bias frequency and the sampling frequency unless a low pass
>>> filter completely removes the bias frequency.
>>>> d
>>>> 
>>>> 
>>>>  On Monday, November 23, 2015 8:42 AM, Tom Fine <
>>> [log in to unmask]> wrote:
>>>> 
>>>> 
>>>> Correction -- I meant to say:
>>>> "Then there's the fact that some tapes AREN'T slit perfectly enough to
>>> ride through the transport
>>>> with relatively even track-tracking (i.e. relatively perfect azimuth
>>> throughout the tape)."
>>>> 
>>>> For what it's worth, Irish/Ampex/Quantegy battled slitting-imperfection
>>> issues throughout its
>>>> existence. 3M slitting was generally better, as was BASF and Agfa and,
>>> I'm guessing (due to no
>>>> experience with the product), EMI. Audio Devices (AudioTape) was also
>>> generally slit precisely.
>>>> 
>>>> Keep in mind too that age physically distorts some tapes, so the ride
>>> across the heads is even less
>>>> perfect. We all know about acetate tapes warping and curling and
>>> shrinking. There hasn't been much
>>>> science done on baking polyester tapes and whether that creates
>>> transport-azimuth issues. My own
>>>> experience is that some tapes do have issues because, after baking,
>>> there is some non-sticky residue
>>>> on the tape surface and edges. This problem can probably be mitigated
>> by
>>> running a baked tape across
>>>> a Pelon wipe before transfer.
>>>> 
>>>> My main point is -- and you can test this with sine-wave and
>> square-wave
>>> signals on even the most
>>>> modern and well-maintained tape machines -- tape is far from
>>> output=input, so it's falacious to say
>>>> its output is "steady-state" fidelity to the original source. Tape's
>> own
>>> mechanical and electrical
>>>> imperfections are constantly "chopping bits off" the original signal,
>>> and thus reducing resolution.
>>>> Same with disk recording and playback.
>>>> 
>>>> -- Tom Fine
>>>> 
>>>> ----- Original Message ----- From: "Tom Fine" <
>> [log in to unmask]
>>>> 
>>>> To: <[log in to unmask]>
>>>> Sent: Monday, November 23, 2015 7:27 AM
>>>> Subject: [ARSCLIST] What is really higher resolution?
>>>> 
>>>> 
>>>>> There is an argument to be made that analog media playback can't
>>> possibly offer that many data
>>>>> points to be collected. To wit ...
>>>>> 
>>>>> 1. when you play a tape, you are fighting the laws of physics. For one
>>> thing, no transport
>>>>> provides a perfect ride across the heads. Resolution is damaged by wow
>>> and flutter (time-smear),
>>>>> plus imperfect tape-to-head contact cause by anything from uneven head
>>> wear to imperfections in
>>>>> the tape surface to simple dust and other particles in the air.
>> There's
>>> also static electricity
>>>>> and other results of friction. Then there's the fact that some tapes
>>> are slit perfectly enough to
>>>>> ride through the transport with relatively even track-tracking (i.e.
>>> relatively perfect azimuth
>>>>> throughout the tape). Tape electronics, especially old ones, are prone
>>> to what are now considered
>>>>> high levels of distortion and noise, and unless they have been
>>> thoroughly overhauled, aging
>>>>> components compound these problems.
>>>>> 
>>>>> 2. a commercial disk release has mechanically-lowered resolution from
>>> the get-go. There are some
>>>>> issues with lacquer "memory" (where the groove shrinks back a little
>>> bit when it cools after
>>>>> cutting -- this is a controversial topic among cutting engineers, but
>>> direct-metal mastering was
>>>>> invented as a solution to this alleged problem). Then there is
>>> resolution-loss in the plating
>>>>> process, because the laws of materials science and physics say it's
>>> impossible to make a perfect
>>>>> imprint (there is some granularity to all materials, plating cannot be
>>> perfectly uniform, etc).
>>>>> And, the pressing machines can't be perfectly clean on every press,
>> the
>>> vinyl biscuit can't be
>>>>> perfectly pure, etc. In fact, if you think about disk-manufacturing,
>>> it's quite miraculous that
>>>>> the whole system got to where it can sound as good as some records do.
>>> With shellac records, it's
>>>>> even more so because the technologies hadn't evolved as much and
>>> shellac itself is a very
>>>>> imperfect carrier material. So, before a stylus even hits the groove,
>>> you have stages of materials
>>>>> imperfections baked in (literally), which results in at least surface
>>> noise if not ticks, pops and
>>>>> groove distortion. And then there's the matter that no stylus tracks a
>>> groove perfectly, there is
>>>>> an inherent noise floor in all mechanical playback (dragging a diamond
>>> through a groove), and that
>>>>> only the very best preamps offer super-low noise floors (this is even
>>> more of an issue with
>>>>> low-output moving-coil setups).
>>>>> 
>>>>> One argument made by the anti-digital crowd of yore (I don't hear this
>>> argument made about
>>>>> higher-resolution digital, except by ideologue zealots) is, "no matter
>>> how much you sample a sound
>>>>> wave, you're still breaking it into chunks and it's not a steady-state
>>> wave." But, see above. The
>>>>> output from the analog playback system itself is not really a
>>> steady-state wave. Physics and
>>>>> materials science prevent that from being so. So the question is,
>> which
>>> system is actually
>>>>> capturing more "resolution"? Let the debate begin!
>>>>> 
>>>>> -- Tom Fine
>>>>> 
>>>>> ----- Original Message ----- From: "Corey Bailey" <
>>> [log in to unmask]>
>>>>> To: <[log in to unmask]>
>>>>> Sent: Monday, November 23, 2015 3:14 AM
>>>>> Subject: Re: [ARSCLIST] Hi-Rez symphony recordings
>>>>> 
>>>>> 
>>>>>> Correction:
>>>>>> Data points per bit should have read: data points per dB of dynamic
>>> range (I changed the math,
>>>>>> but not the description).
>>>>>> So, the comparison should read:
>>>>>> 
>>>>>> Lets take a look at the available data points for each dB of dynamic
>>> range for CD quality digital
>>>>>> audio: 65,536 (data points) divided by 96 (dB of dynamic range) =
>>> 682.6 data points for each dB
>>>>>> of dynamic range of a given sample.
>>>>>> 
>>>>>> Compare that to 24 Bit/ 96K digital audio: 4,294,967,296 (data
>> points)
>>> divided by 144 (dB of
>>>>>> dynamic range) = 29,826,161 data points for each dB of dynamic range
>>> of a given sample. And,
>>>>>> there are more than twice a many samples taken! Now, we are talking
>>> about some decent resolution.
>>>>>> 
>>>>>> Also, my hand typed chart got wacked by the forum formatting.
>>> Hopefully, you get the idea.
>>>>>> 
>>>>>> Cheers!
>>>>>> 
>>>>>> Corey
>>>>>> Corey Bailey Audio Engineering
>>>>>> www.baileyzone.net
>>>>>> 
>>>>>>> On 11/22/2015 7:47 PM, Corey Bailey wrote:
>>>>>>> Mr. Kevil:
>>>>>>> Let's take a look at Bit Depth as applied to digital audio: "Bit
>>> Depth divides a given sample
>>>>>>> by its value."
>>>>>>> Thus:
>>>>>>> BIT DEPTH DATA POINTS DYNAMIC RANGE
>>>>>>> 8 256 48dB
>>>>>>> 
>>>>>>> 16 65,536 96dB
>>>>>>> 
>>>>>>> 24 4,294,967,296 144dB
>>>>>>> 
>>>>>>> Now, lets take a look at the available data points per bit for CD
>>> quality digital audio: 65,536
>>>>>>> (data points) divided by 96 (dB of dynamic range) = 682.6 data
>> points
>>> for each bit of a given
>>>>>>> sample.
>>>>>>> 
>>>>>>> Compare that to 24 Bit/ 96K digital audio: 4,294,967,296 (data
>>> points) divided by 144 (dB of
>>>>>>> dynamic range) = 29,826,161 data points for each bit of a given
>>> sample. And, there are more than
>>>>>>> twice a many samples taken! Now, we are talking about some decent
>>> resolution.
>>>>>>> 
>>>>>>> So, even though you have only 70 dB of dynamic range available for
>>> those old tape recordings
>>>>>>> (before the introduction of Noise Reduction), you will obviously
>>> capture much more of that
>>>>>>> available dynamic range using the archival standard 24Bit/96K (Hi
>>> Rez) sample rate and bit
>>>>>>> depth.
>>>>>>> 
>>>>>>> The same logic applies to any of the old audio carriers.
>>>>>>> 
>>>>>>> Plus, when restoration takes place, the results are less artifact
>>> prone when using higher bit
>>>>>>> depths and sample rates.
>>>>>>> 
>>>>>>> Cheers!
>>>>>>> 
>>>>>>> Corey
>>>>>>> Corey Bailey Audio Engineering
>>>>>>> www.baileyzone.net
>>>>>>> 
>>>>>>> 
>>>>>>>> On 11/22/2015 3:03 PM, L. Hunter Kevil wrote:
>>>>>>>> A transfer of a 1960s tape marketed in a 24/96 wrapper is what?
>>> Doesn't the resolution of the
>>>>>>>> tape correspond to the equivalent of an 8- or 12-bit word? If so,
>>> what does the wrapper do?
>>>>> 
>>>>> 
>>> 
>> 
>> 
>> 
>> --
>> Ellis
>> [log in to unmask]
>> 818-846-5525
>> 

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