Feedback in audio esp wrt op-amps.

[John Larkin]

On 21 Aug 2007 06:46:06 GMT, Robert Latest <boblatest@yahoo.com>
wrote:

Eeyore wrote:

The idea that you can 'get away' with sloppy circuitry for replay because the
source was in some way 'impaired' is totally false.

I don't think anybody proposed "sloppy" circuitry for replay. The point is
that studio audio gear is just solid, reliable, conventional good audio
stuff (none of that high-end low-oxygen power cord crap). Plenty of opamps,
plenty of NFB, plenty of digital processing, plenty of all the things that
high-enders loathe.

Since the recording studio already did 90% of the work of completely
destroying the audio signal beyond repair, it doesn't matter how much your
home audio gear adds to that.

Sometimes when I hear the golden earers talk I'm surprised that I can make
out any music at all when listening with my Cantons fed from an old Sony amp
through particularly oxygen-rich cables.

robert

Designing audio playback gear that has PPM distortion levels, and
noise so low it's dominated by the source material and room
background, is now so easy it's not worth discussing. Just grab some
National appnotes and opamp datasheets. Because it's so easy to make
measurable noise and distortion vanishingly small, the audiophools
have had to move on to debating the unmeasurable, in long threads with
no content.

John

 

[Mogens V.]

Scott Dorsey wrote:

Eeyore <rabbitsfriendsandrelations@hotmail.com> wrote:

That's not what we're talking about.

You can tune most instruments to these scales.


Except the piano, which you can't really tune to _any_ scale...
--scott

About the same with a guitar, which can be tuned open string or using
some tuning strategy, but even with a fretjob based on i.e. the
Buzz-Feiten system (or other semilar systems), it'll be a Bit out of
tune most everywhere on the scale.

I find this whole discussion very interesting for understanding sound
quality both for recording and replaying, and most cirtainly also the
other way around, for _creating_ a tone/sound.
As always, I learn a lot in here..


The discussion on intonation struck me. Most western music is pretty
simple in terms of intonation. But try listening to ethnic culture
music, like an African choir or Indian music; can be quite defferent..
As a progressive metal guitar player, I often create dissonant chords,
and lately started experimenting with out of scale string bending, kinda
like using a micro-scale fretted instrument.

Given the 'right' gear, such chords and scales can sound 'good' (surely
a matter of subjective taste), with other gear such becomes extremely
dissonantly unpleasing.
It's an example of understanding electronics WRT tone creation, though
AFAICS is equally related to being able to record and reproduse such.

--
Kind regards,
Mogens V.

 

[Peter Larsen]

"Mogens V." wrote:

The discussion on intonation struck me. Most western music
is pretty simple in terms of intonation.

You need to listen more to classical string quartets performing live.

In your own genre you need to listen to early Velvet Underground and
Mothers of Invention, neither were very adept at tuning their
instruments initially ... O;-) ... Velvet Underground especially had
their very own tonal landscape.

Mogens V.

Kind regards

Peter Larsen

 

[Kevin Aylward]

Arny Krueger wrote:

"Eeyore" <rabbitsfriendsandrelations@hotmail.com> wrote in message
news:46CD01A2.F28D9D7B@hotmail.com...


isw wrote:

"William Sommerwerck" <grizzledgeezer@comcast.net> wrote:

The spectrum is important, in fact it is critical. In many cases,
2nd order distortion is hard to hear, particularly when listening
to solo instruments. This is due to concurrent spectral masking
in the human ear.

Higher order harmonics are not so well masked as 2nd, so the ear
can pick them out, even when they are relatively small.

The audibility of harmonic distortion might also depend on tuning.
In a system using whole-number ratios, harmonic distortion of all
orders might be
less audible than in a tempered system.

Most instruments produce overtones as well as -- or instead of --
harmonics. They don't fall directly on multiples of the fundamental
no matter what tuning is used.

The technical definition of an overtone is no different from a
harmonic other than
its number.

1st overtone = 2nd harmonic etc.

Overtones are a superset of the set of harmonics:

Wikipedia:

"

Overtone:

An overtone is a sinusoidal component of a waveform, of greater
frequency (usually an integer number multiple) than its fundamental
frequency. The term is usually used in music, rather than wave
physics. (see standing wave)

I disagree with this.

An overtone is the natural resonances of a sound source. That is, the
natural modes of vibration. I disagree that the definition has anything to
do with integral multiples of a fundamental. It just so happens that
overtones are often quite close to harmonics. For example, the 2nd overtone
of a drum is 2.4 times its fundamental (given by the roots of Jo, the Bessel
function).

For example, even guitar "harmonics" are not harmonics. The string does not
vibrate exactly at a length set by the nut and bridge. The string does not
move until it is a little away from its fulcrums. This is aproximinatly a
fixed length, that depends on the string thichness/mass density/stiffness. A
first order correction to this is to angle the bridge so that the thinner
strings are shorter than the thicker strings. The net effect is that string
overtones are not integral multiples of a fundamental as halving the string
length, does not half the actual vibration length.

This effect is even more pronounced in brass instruments. This why they have
a bell at the end. Not as a horn to make it louder, but as end correction to
make the thing play nearer to regular harmonics.

When one does the standard physics of blown tubes etc, in 101 whatever, it
is easier to forget that these treatments are just approximations for
drunken students who would rather have their bell end sucked than blowed.


--
Kevin Aylward
ka@kevinaylward.co.uk

 

[Terry Given]

Kevin Aylward wrote:

Arny Krueger wrote:

"Eeyore" <rabbitsfriendsandrelations@hotmail.com> wrote in message
news:46CD01A2.F28D9D7B@hotmail.com...


isw wrote:


"William Sommerwerck" <grizzledgeezer@comcast.net> wrote:


The spectrum is important, in fact it is critical. In many cases,
2nd order distortion is hard to hear, particularly when listening
to solo instruments. This is due to concurrent spectral masking
in the human ear.

Higher order harmonics are not so well masked as 2nd, so the ear
can pick them out, even when they are relatively small.

The audibility of harmonic distortion might also depend on tuning.
In a system using whole-number ratios, harmonic distortion of all
orders might be
less audible than in a tempered system.

Most instruments produce overtones as well as -- or instead of --
harmonics. They don't fall directly on multiples of the fundamental
no matter what tuning is used.

The technical definition of an overtone is no different from a
harmonic other than
its number.

1st overtone = 2nd harmonic etc.

Overtones are a superset of the set of harmonics:

Wikipedia:

"

Overtone:

An overtone is a sinusoidal component of a waveform, of greater
frequency (usually an integer number multiple) than its fundamental
frequency. The term is usually used in music, rather than wave
physics. (see standing wave)


I disagree with this.

An overtone is the natural resonances of a sound source. That is, the
natural modes of vibration. I disagree that the definition has anything to
do with integral multiples of a fundamental. It just so happens that
overtones are often quite close to harmonics. For example, the 2nd overtone
of a drum is 2.4 times its fundamental (given by the roots of Jo, the Bessel
function).

For example, even guitar "harmonics" are not harmonics. The string does not
vibrate exactly at a length set by the nut and bridge. The string does not
move until it is a little away from its fulcrums. This is aproximinatly a
fixed length, that depends on the string thichness/mass density/stiffness. A
first order correction to this is to angle the bridge so that the thinner
strings are shorter than the thicker strings. The net effect is that string
overtones are not integral multiples of a fundamental as halving the string
length, does not half the actual vibration length.

This effect is even more pronounced in brass instruments. This why they have
a bell at the end. Not as a horn to make it louder, but as end correction to
make the thing play nearer to regular harmonics.

When one does the standard physics of blown tubes etc, in 101 whatever, it
is easier to forget that these treatments are just approximations for
drunken students who would rather have their bell end sucked than blowed.

best post yet, Kevin

Cheers
Terry

 

[Mr.T]

"Scott Dorsey" <kludge@panix.com> wrote in message
news:fak08u$4qm$1@panix2.panix.com...

Pull the cover on an SSL 4000 and look inside. Or just look at the
schematic.

You keep saying that as if it proves something all by itself ???

While you're staring at all the chips next time, why not actually shove a
test signal in and measure the result at the output. I think you will not
find any significant problems unless it is broken.

Well, what comes out sure sounds a whole lot different than what went in,
so I would suspect a measurement would indicate that too.

Ah, what you "suspect" may be wrong too. That's why I prefer to actually
measure these things.

Bob Pease has a wonderful classroom demo in which he shows a 1 KC square
wave through a fairly clean op-amp stage, then through a hundred, and
then through a huge board with a thousand op-amps on it. A small error
gets exaggerated substantially.

And many people have put a kHz square wave into a SSL console without any
problem, or they would simply use a Behringer instead!

MrT.

 

[Scott Dorsey]

Mr.T <MrT@home> wrote:

"Scott Dorsey" <kludge@panix.com> wrote in message
news:fak08u$4qm$1@panix2.panix.com...
Pull the cover on an SSL 4000 and look inside. Or just look at the
schematic.

You keep saying that as if it proves something all by itself ???

Well, you take your finger from the input... then you move it stage by
stage until you get to the tape send... then you move it stage by stage
from the tape return to the 2-buss... and count how many op amps you
pass through. Hint: it's more than fifty.

Well, what comes out sure sounds a whole lot different than what went in,
so I would suspect a measurement would indicate that too.

Ah, what you "suspect" may be wrong too. That's why I prefer to actually
measure these things.

It would be interesting to measure, but thank God I don't have one sitting
around here.

Bob Pease has a wonderful classroom demo in which he shows a 1 KC square
wave through a fairly clean op-amp stage, then through a hundred, and
then through a huge board with a thousand op-amps on it. A small error
gets exaggerated substantially.

And many people have put a kHz square wave into a SSL console without any
problem, or they would simply use a Behringer instead!

I have heard plenty of stuff come out of SSL consoles that sure sounded like
square waves, but that's an operator issue.

Still, the 1KC square wave test is a hell of a good qualitative measurement.
You get to see any stability issues and any frequency response variations
very quickly on the scope.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

 

[D from BC]

On Thu, 23 Aug 2007 08:19:17 -0700, John Larkin
<jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

On 21 Aug 2007 06:46:06 GMT, Robert Latest <boblatest@yahoo.com
wrote:

["Followup-To:" header set to sci.electronics.design.]
Eeyore wrote:

The idea that you can 'get away' with sloppy circuitry for replay because the
source was in some way 'impaired' is totally false.

I don't think anybody proposed "sloppy" circuitry for replay. The point is
that studio audio gear is just solid, reliable, conventional good audio
stuff (none of that high-end low-oxygen power cord crap). Plenty of opamps,
plenty of NFB, plenty of digital processing, plenty of all the things that
high-enders loathe.

Since the recording studio already did 90% of the work of completely
destroying the audio signal beyond repair, it doesn't matter how much your
home audio gear adds to that.

Sometimes when I hear the golden earers talk I'm surprised that I can make
out any music at all when listening with my Cantons fed from an old Sony amp
through particularly oxygen-rich cables.

robert

Designing audio playback gear that has PPM distortion levels, and
noise so low it's dominated by the source material and room
background, is now so easy it's not worth discussing. Just grab some
National appnotes and opamp datasheets. Because it's so easy to make
measurable noise and distortion vanishingly small, the audiophools
have had to move on to debating the unmeasurable, in long threads with
no content.

John

The inner ear probably has distortion and there's probably auditory
brain distortion.
Since technology has superceded some biological functions, it maybe
that audiophools should turn to improving inner ear and auditory brain
distortion.

A brief history of hearing...

Cavemen listening for predators....

"Was that the sound of a wolf on moss?"
"Nah..sounds more like tiger on grass?"
(Possible the first audiophools.)

To spoken language...

"Hello...hello...can you hear me now?...How about now?...Wait let me
step out in the open..How about now?"

To mp3's downloaded off the internet....

"I'm a black gangsta...yeah man...black gangsta...motherfkr...yo
man...Boom Boom ka boom...Got me an Uzi cause I smoozee...Cause I
boozy.. yeah ... I'm a black gangsta."

Is there really a need for perfect audio... I don't think so..
D from BC

 

[Mr.T]

"Scott Dorsey" <kludge@panix.com> wrote in message
news:falddn$169$1@panix2.panix.com...

It would be interesting to measure, but thank God I don't have one sitting
around here.

Still, the 1KC square wave test is a hell of a good qualitative
measurement.
You get to see any stability issues and any frequency response variations
very quickly on the scope.

So when you've actually done it, get back to us.

MrT.

 

[Eeyore]

Peter Larsen wrote:

Eeyore wrote:

You can tune most instruments to these scales.

Unless they have to play with tempered instruments.

Then it's the instruments with the equal temperament that are excluded from such
performances.

Graham

 

[Eeyore]

John Larkin wrote:

Robert Latest wrote:

["Followup-To:" header set to sci.electronics.design.]

Original groups replaced

Eeyore wrote:

The idea that you can 'get away' with sloppy circuitry for replay because the
source was in some way 'impaired' is totally false.

I don't think anybody proposed "sloppy" circuitry for replay. The point is
that studio audio gear is just solid, reliable, conventional good audio
stuff (none of that high-end low-oxygen power cord crap). Plenty of opamps,
plenty of NFB, plenty of digital processing, plenty of all the things that
high-enders loathe.

Since the recording studio already did 90% of the work of completely
destroying the audio signal beyond repair, it doesn't matter how much your
home audio gear adds to that.

Sometimes when I hear the golden earers talk I'm surprised that I can make
out any music at all when listening with my Cantons fed from an old Sony amp
through particularly oxygen-rich cables.


Designing audio playback gear that has PPM distortion levels, and
noise so low it's dominated by the source material and room
background, is now so easy it's not worth discussing.

Simply not true. But seemingly believed by some people who should know better and
who apparently foolishly think audio is entirely trivial these days.

Power amplifiers in particular still regularly have THD levels as high as 1000 ppm
(and more sometimes). And that's normally measured at full power which is a
relatively easy figure to obtain. THD @ real listening levels of around the 100mW to
1W mark may be considerably higher.

Just grab some National appnotes and opamp datasheets. Because it's so easy to
make
measurable noise and distortion vanishingly small,

What's the ppm THD of a National IC power amplifier ? Certainly not in the single
digits ppm !

the audiophools have had to move on to debating the unmeasurable, in long threads
with
no content.

More uninformed ignorance.

The difference between the audiophools who argue for such nonsense voodoo as
cryogenically treated and 'broken in' cables and the like is quite different from
this discussion which is based in sound science.

Graham

 

[Arny Krueger]

"Kevin Aylward" <none@none.com> wrote in message
newsalzi.25186$ph7.2547@newsfe5-win.ntli.net

Arny Krueger wrote:
"Eeyore" <rabbitsfriendsandrelations@hotmail.com> wrote
in message news:46CD01A2.F28D9D7B@hotmail.com...


isw wrote:

"William Sommerwerck" <grizzledgeezer@comcast.net
wrote:
The spectrum is important, in fact it is critical.
In many cases, 2nd order distortion is hard to hear,
particularly when listening to solo instruments.
This is due to concurrent spectral masking in the
human ear.

Higher order harmonics are not so well masked as
2nd, so the ear can pick them out, even when they
are relatively small.

The audibility of harmonic distortion might also
depend on tuning. In a system using whole-number
ratios, harmonic distortion of all orders might be
less audible than in a tempered system.

Most instruments produce overtones as well as -- or
instead of -- harmonics. They don't fall directly on
multiples of the fundamental no matter what tuning is
used.

The technical definition of an overtone is no different
from a harmonic other than
its number.

1st overtone = 2nd harmonic etc.

Overtones are a superset of the set of harmonics:

Wikipedia:

Overtone:

An overtone is a sinusoidal component of a waveform, of
greater frequency (usually an integer number multiple)
than its fundamental frequency. The term is usually used
in music, rather than wave physics. (see standing wave)

I disagree with this.

An overtone is the natural resonances of a sound source.

....above the fundamental, although the term "first overtone" is in use.

That is, the natural modes of vibration. I disagree that
the definition has anything to do with integral multiples
of a fundamental.

The set of tones that are "..of greater frequency.." includes both harmonic
and inharmonic tones. Natural resonances of a sound source may be harmonic
or inharmonic, depending on the source.

It just so happens that overtones are
often quite close to harmonics. For example, the 2nd
overtone of a drum is 2.4 times its fundamental (given by
the roots of Jo, the Bessel function).

Probably not a happenstance. Some objects vibrate quite nonlinearly, and
thus produce inharmonic overtones. Percussion instruments seem to be more
prone to this sort of thing.

For example, even guitar "harmonics" are not harmonics.
The string does not vibrate exactly at a length set by
the nut and bridge. The string does not move until it is
a little away from its fulcrums. This is aproximinatly a
fixed length, that depends on the string thichness/mass
density/stiffness. A first order correction to this is to
angle the bridge so that the thinner strings are shorter
than the thicker strings. The net effect is that string
overtones are not integral multiples of a fundamental as
halving the string length, does not half the actual
vibration length.

If you're describing what different strings do, then this is different than
vibrating bodies that product harmonic and inharmonic tones.

 

[Peter Larsen]

Arny Krueger wrote:

Probably not a happenstance. Some objects vibrate quite
nonlinearly, and thus produce inharmonic overtones.
Percussion instruments seem to be more prone to this sort
of thing.

This issue is most interestingly explained in a 1981 +/- one or two
years issue of Scientific American on piano tuning

For example, even guitar "harmonics" are not harmonics.
The string does not vibrate exactly at a length set by
the nut and bridge. The string does not move until it is
a little away from its fulcrums. This is aproximinatly a
fixed length, that depends on the string thichness/mass
density/stiffness. A first order correction to this is to
angle the bridge so that the thinner strings are shorter
than the thicker strings. The net effect is that string
overtones are not integral multiples of a fundamental as
halving the string length, does not half the actual
vibration length.

If you're describing what different strings do, then this is
different than vibrating bodies that product harmonic and
inharmonic tones.

What strings do depend on what their anchor points do. See the
literature reference above.

Kind regards

Peter Larsen

 

[Mogens V.]

Peter Larsen wrote:

Arny Krueger wrote:


Probably not a happenstance. Some objects vibrate quite
nonlinearly, and thus produce inharmonic overtones.
Percussion instruments seem to be more prone to this sort
of thing.


This issue is most interestingly explained in a 1981 +/- one or two
years issue of Scientific American on piano tuning


For example, even guitar "harmonics" are not harmonics.
The string does not vibrate exactly at a length set by
the nut and bridge. The string does not move until it is
a little away from its fulcrums. This is aproximinatly a
fixed length, that depends on the string thichness/mass
density/stiffness. A first order correction to this is to
angle the bridge so that the thinner strings are shorter
than the thicker strings. The net effect is that string
overtones are not integral multiples of a fundamental as
halving the string length, does not half the actual
vibration length.



If you're describing what different strings do, then this is
different than vibrating bodies that product harmonic and
inharmonic tones.


What strings do depend on what their anchor points do. See the
literature reference above.

That's a bit too generalized. It also depends on the rest of the
physical swinging system. Unless counting all beneath strings as anchor,
mounting the same set of strings, tuners, nut, bridge on a solid steel
railway chunk, an acoustic, an electric solidbody and a archtop jazz
guitar yeilds different string movements.
Sorry, no references I can remember. And a bit OT to the discussion.

--
Kind regards,
Mogens V.

 

[Rich Grise]

On Fri, 24 Aug 2007 10:48:28 +0100, Eeyore wrote:

Peter Larsen wrote:
Eeyore wrote:

You can tune most instruments to these scales.

Unless they have to play with tempered instruments.

Then it's the instruments with the equal temperament that are excluded from such
performances.

Yeah, ha ha, but temper and temperament are in entirely different
ballparks.

In High School, I broke my collarbone while horsing around. When I got
home from getting it set, my sister asked, "Did you break your well-
tempered clavicle?" ;-)

We all laugued politely.

Thanks,
Rich

 

[Mogens V.]

Eeyore wrote:

There was part of a thread a while back about how adding negative feedback can
create higher order harmonic distortion products than exist open-loop in an
amplifier stage.

This made me think about the application of op-amps in audio generally. Negative
feedback is used primarily to linearise the transfer function and is used in
huge quantites as much as 80dB @ 1 kHz for example.

Since this amount of NFB is not required to provide an accurate gain setting, it
struck me that it's somewhat counter productive. If instead the open-loop
transfer characteritic was made more linear by degeneration of the open-loop
gain for example, when NFB is applied, the overall result should be largely
similar (i.e. no worse) but would presumably also suffer less from the creation
of these new distortion products .

Comments ?

Graham

Maybe useful to the discussion on harmonics, YMMV.. it's some graphs of
audibility for different harmonics:

http://members.cox.net/alexhardware/opa.htm

--
Kind regards,
Mogens V.

 

[Arny Krueger]

"Mogens V." <mogensv@NOYOUDONTvip.cybercity.dk> wrote in
message
news:46cfecce$0$21928$157c6196@dreader1.cybercity.dk

Maybe useful to the discussion on harmonics, YMMV.. it's
some graphs of audibility for different harmonics:

http://members.cox.net/alexhardware/opa.htm

Figure one seems to be highly speculative. Where did it come?

 

[Mogens V.]

Arny Krueger wrote:

"Mogens V." <mogensv@NOYOUDONTvip.cybercity.dk> wrote in
message
news:46cfecce$0$21928$157c6196@dreader1.cybercity.dk

Maybe useful to the discussion on harmonics, YMMV.. it's
some graphs of audibility for different harmonics:

http://members.cox.net/alexhardware/opa.htm


Figure one seems to be highly speculative. Where did it come?

I really can't say.. I stumbled over this from some audiophile forum
while searching for references to peoples experiences with opamps.

The article has a nof links to some modified 'board' seemingly in some
CD/SACD player, the make and model of which I can't make out, which
seems to be the basis for the tests.
Right above Fig 1 this 'board' seemingly used for measurements are
mentioned, indicating they did measure out those opamps - or maybe the
player was measured as a whole.
But you're right, the way it's written, Fig 1 could be based on some
measurements coupled with a mix of theory, experiences and speculations
(or superstition, it you will).

The article has a link to Part 1 somewhere near the top.
Both papers have a nof subjective listening comments, so YMMV..

The reason I put some faith in the papers is that most all comments on
subjective sonic performance seems to fit with what I read elsewhere,
which of cause doesn't nessesarily make it technically valid.

--
Kind regards,
Mogens V.

 

[Arny Krueger]

"Mogens V." <mogensv@NOYOUDONTvip.cybercity.dk> wrote in
message
news:46d29524$0$21926$157c6196@dreader1.cybercity.dk

Arny Krueger wrote:
"Mogens V." <mogensv@NOYOUDONTvip.cybercity.dk> wrote in
message
news:46cfecce$0$21928$157c6196@dreader1.cybercity.dk

Maybe useful to the discussion on harmonics, YMMV.. it's
some graphs of audibility for different harmonics:

http://members.cox.net/alexhardware/opa.htm


Figure one seems to be highly speculative. Where did it
come?

I really can't say.. I stumbled over this from some
audiophile forum while searching for references to
peoples experiences with opamps.

The article has a nof links to some modified 'board'
seemingly in some CD/SACD player, the make and model of
which I can't make out, which seems to be the basis for
the tests.

The tests they allude to seem to, er lack rigor.

Right above Fig 1 this 'board' seemingly used for
measurements are mentioned, indicating they did measure
out those opamps - or maybe the player was measured as a
whole.

The analog domain circuitry in a CD player is basically a stereo DAC, a pair
of op amps, and maybe an analog switch for muting.

But you're right, the way it's written, Fig 1 could be
based on some measurements coupled with a mix of theory,
experiences and speculations (or superstition, it you
will).

I'm thinking it has a lot of the latter, because the thresholds shown are
below the generally agreed-upon state of the human ear, and by several
orders of magnitude.

The article has a link to Part 1 somewhere near the top.
Both papers have a nof subjective listening comments, so
YMMV..

Exactly. It's highly speculative stuff. If someone said that they took the
current understandings of the sensitivity of the ear, and added 2-3 orders
of magnitude "safety factor", I might understand.

The reason I put some faith in the papers is that most
all comments on subjective sonic performance seems to fit
with what I read elsewhere, which of cause doesn't
nessesarily make it technically valid.

There's a lot of people who say this kind of stuff, and it appears to rock
their cradle. Doesn't make it the least bit true.

 

[Mogens V.]

Arny Krueger wrote:

"Mogens V." <mogensv@NOYOUDONTvip.cybercity.dk> wrote

Right above Fig 1 this 'board' seemingly used for
measurements are mentioned, indicating they did measure
out those opamps - or maybe the player was measured as a
whole.


The analog domain circuitry in a CD player is basically a stereo DAC, a pair
of op amps, and maybe an analog switch for muting.

Basically, yes. Sometimes I wonder about all that electronics in some
devices. The reference thingy (an SACD, it seems) in said article seems
to be loaded with electronics. YMMV..

The reason I put some faith in the papers is that most
all comments on subjective sonic performance seems to fit
with what I read elsewhere, which of cause doesn't
nessesarily make it technically valid.


There's a lot of people who say this kind of stuff, and it appears to rock
their cradle. Doesn't make it the least bit true.

Nod. As I said, I was searching for tonal references more than tech
facts. It's for modding the analog part of guitar processors, where a
nof devices will all serve equally well, from a tech POW.
Not having the time nor the test gear, I was going more for a matching
range of subjective sonic comments. The tonal/sonic 'findings' in the
referred article mostly seem to match what's been commented in here, so
at least subjectively, it's not totally off.
I fully agree with your comments on scale et al.., though
Haven't completely lost my ability to think and read between lines..

--
Kind regards,
Mogens V.