Toob sound?

[John Larkin]

There is a tube sound, as in guitar amps *unclipped*, and it is measures
easily as a tube sound, like in the 1% range. However, I agree that
*hi-fi* tube amps of good quality, all things being equal, all sound the
same as trany amps.

There is also more to the simulation then just clipping distortion, e.g.
the output impedance of a tube amp can be several ohms. Speakers vary
over the frequency range of say, 6 to 200 for a nominal 8 ohm. Indeed,
when a tube amp clips, it generats x-over distortion. Have a look at the
waveform on a scope some time. The coupling caps start charging when the
grid starts taking current.

You have to compare apples with apples. Guitar amps are *not*, hi-fi
amps, so they do have a sound.

I designed a transistor guitar amp once, a private-label thing for a
chain of Southern US music stores. I think it was called the Ryder 400
or something silly (after Frank Ryder, one of my techs at that time
and an astounding aerobatic pilot; only time I've ever been motion
sick, Frank did it.) The amp was 'hi-fi' so sounded flat, so I
breadboarded a bunch of distortion circuits until the owner guy liked
the sound. It wound up having a softish symmetric diode clipper with a
tracking clip level and a bit of differentation, just a couple of
diodes and a few R-Cs in the end, with a user adjustment for how much
of this mess was mixed into the main signal. Some people liked it; it
added a bell-like quality to the sound, long sustain, not a hard
fuzz-tone thing.

But audio tends to be boring, low-margin business.

John

 

[gwhite]

Unfortunatly or rather fortunately all these arguments loose ground when you
compare a record player with a recorded CD from the same player. Then the
phono freak cannot distinguish between the the 2 in a Double Blind Test.
Which IMHO proofs the transparency of the CD as medium.

I havn't heard of this test but you could do it at home NT and then have a
friend help you to switch amps without your knowledge. You have to use the
same listening level when recording and have a simple attenuator in front of
the soundcard consisting of a simple 10k and 470 ohms -27dB attenuator.

Unfortunately, I don't think a double blind test is nearly that easy.
What I mean by this is that the CD will be superior to the LP in ways
that are *easily identifiable* to the listener. The most obvious of
this is the low level pops and clicks of the LP, which are entirely
absent from a CD. So "double blind" under your description is *not*
double blind -- the listener can easily identify the source with pops
and clicks and maybe even rumble, as the LP source. Thus listener bias
could not be eliminated with this sort of "straight double blind test."

The test must be designed to prevent this. In absolute terms, I don't
think it is possible. The CD will always be identifiable compared to an
LP with _otherwise identical hardware and music program material_.

What I believe may be of more interest, and more practical, is to test
all those golden eared hi-fi audiophiles for identifying "graininess" or
whatever they claim the demerits of standard 16-bit CD audio are *in
comparison* the to claimed merits of LP's.

I would propose *adding* phono type pops, clicks, wow-flutter, and
rumble to a CD recording at the same S/(N + otherBadStuff) ratio that
would be present on an LP. (It could be done by recording the playback
of a blank LP and summing it to the music source.) Thus it would not be
obvious to the listener which source was the CD or LP during testing,
thereby eliminating that source of bias. One could even take the actual
LP, play it, and record it to CD.

If the listeners could consistantly ID the sources, then there may be
some truth to the complaints about CD's. If the sources can't be ID'ed,
then the comparative performance question between LP and CD can be
dispensed with forever.

This test could not "prove" anything other than the _comparative_ level
of performance. That is, it does not prove that audiphile listeners
can't hear quantization ("graininess") of the 16-bit audio signals when
LP style degradations are not present in the medium. It could only show
that LP's S/(N + otherBadStuff) ratio is sufficiently bad (good) to
swamp (highlight) the CD formats shortcomings.

If the LP's "N + otherBadStuff" swamps the CD's "N + otherBadStuff",
then it would be logically difficult to justify the LP over CD.

This more limited falsification test is more practical as it compensates
for bias.

 

[[email protected]]

[email protected] wrote:

Adding distortion can make things sound cleaner. That is sort of a
mystary.


Its not all in the mind. Minds prefer distortion for some applications.
For others, they don't.

Kevin Aylward

That sounds like sense.

I've added deliberate distortion to low end before kit to make it sound
better. Frexample modulating the sound with mains ripple really warms
the bass up, and is how old valve radios sound warm despite their
crappy bass response. Just put some hum on any pin that achieves this
multiplying, but does not add it. Adding gives hum, multiplying gives
warm bass without hum.


NT

 

[[email protected]]

[email protected] wrote:

I think it is quite simple. You are used to the euphonic distortion of a
tube amp that gives the illusion of a more "spacy" or deep soundstage,
especially when combined with a phono turntable.

does it? AIUI phono gives less dynamic range, not more, than CD. And
more crosstalk, giving less stereo depth.

I bet your opinion is also,
that a black record played on a decent phono rig is superiour or sounds more
lifelike than a CD.
huh?


And I also bet your opinion why digital is bad
huh?


is because of the "staircase"
quantized and discrete values of digital compared to the continuity of
analog.

this is gettin silly.

Unfortunatly or rather fortunately all these arguments loose ground

when you

....when you realise that you made them up in order to shoot them down,
while claiming theyre someone else's claims. Its called a straw man.

It doesnt tell us a whole lot about the sounds of valves vs trs.

Maybe we should also tap the tube amp output in the same way and then let
the tube fan decide which is the real thing.
I havn't heard of this test but you could do it at home NT and then have a
friend help you to switch amps without your knowledge.

I'd like to do that, and see what happens. Unfortunately I have neither
the equipment nor the time these days. I've grown up.

When done come back and tell us. Otherwise better write those stories in
some audiophool forum like that one of Hoffmann or other "high-end"
newsgroups, not in an Engineering NG.

it was you that wrote the silly stories.

If you had offerd a convincing argument for there being no detectable
difference between how valves and trs sound, I'd say you had a
conclusion well worth considering, but you've offerd not a single jot
of evidence for such here.


NT

 

[Keith Williams]

Unfortunately, I don't think a double blind test is nearly that easy.
What I mean by this is that the CD will be superior to the LP in ways
that are *easily identifiable* to the listener. The most obvious of
this is the low level pops and clicks of the LP, which are entirely
absent from a CD. So "double blind" under your description is *not*
double blind -- the listener can easily identify the source with pops
and clicks and maybe even rumble, as the LP source. Thus listener bias
could not be eliminated with this sort of "straight double blind test."

I think Ban was suggesting that the CD be recorded from the vinyl, and
would therefor have those defects as well.

Ban wrote:
"Unfortunatly or rather fortunately all these arguments loose
ground when you compare a record player with a recorded CD from
the same player.:
^^^^^^^^^^^

The test must be designed to prevent this. In absolute terms, I don't
think it is possible. The CD will always be identifiable compared to an
LP with _otherwise identical hardware and music program material_.

The point is that the CD has duplicated these defect "perfectly"
(enough for the ear), thus CDs are not inferior to vinyl.

What I believe may be of more interest, and more practical, is to test
all those golden eared hi-fi audiophiles for identifying "graininess" or
whatever they claim the demerits of standard 16-bit CD audio are *in
comparison* the to claimed merits of LP's.

I would propose *adding* phono type pops, clicks, wow-flutter, and
rumble to a CD recording at the same S/(N + otherBadStuff) ratio that
would be present on an LP. (It could be done by recording the playback
of a blank LP and summing it to the music source.) Thus it would not be
obvious to the listener which source was the CD or LP during testing,
thereby eliminating that source of bias. One could even take the actual
LP, play it, and record it to CD.

Why not just record the vinyl, as Ban has suggested? If the golden-ear
can't distinguish the difference then CDs are better than vinyl, since
they add nothing to the "experience".

If the listeners could consistantly ID the sources, then there may be
some truth to the complaints about CD's. If the sources can't be ID'ed,
then the comparative performance question between LP and CD can be
dispensed with forever.

Exactly.

<snip>

 

[gwhite]

I think Ban was suggesting that the CD be recorded from the vinyl, and
would therefor have those defects as well.

Ban wrote:
"Unfortunatly or rather fortunately all these arguments loose
ground when you compare a record player with a recorded CD from
the same player.:

Doh!


Why not just record the vinyl, as Ban has suggested? If the golden-ear
can't distinguish the difference then CDs are better than vinyl, since
they add nothing to the "experience".

Actually I proposed the same thing -- I just didn't read Ban closely, I
wrote:

"One could even take the actual
LP, play it, and record it to CD."

 

[RoyalHeart]

That "it does" have an impact was exactly his point. So is your point
that CD's "sound better" if LP noise is added? If so, I smell a market
for "noised up" CD's, since it would be cheaper to make CD's noisy (with
LP noise), than to mess with LP's themselves. How about a knob on the
amp, right beside the bass control that says "LP noise?"




Are you claiming that one can "improve perceived sound quality" by
creating distortion, and then modulating that distortion with 50 Hz"
Please explain, because it sounds strange. I have never heard of such
an "enhancement" technique in hi-fi systems.




Why would that be so?




"Cleanest is best" is pretty much the definition of hi-fi. So if you
want to add distortion, you need to explain why you think it helps. Are
you saying you don't like the mix/production of the source material and
distortion will make ot better? That's fine if you do, but that is not
the definition of hi-fi, which seeks to minimize coloration by
definition. That is, it tracks the source with *high fidelity*.




I suppose an LP without these impairments is exceedingly rare, if it
exists at all. This is the common reason of why the tester will be
confused. That is exactly the point and why it is suggested as a test.

If your argument is for a lab instrumentation grade LP and player that
only white-coated lab rats in a clean room see, then you can afford the
same hedge to the CD: give it 24 bits and a 200 k sampling rate.

I've been following this thread mainly out of curiosity.

I own both the cassette tape (remember those?) and CD version of "The
Divine Bette Midler." To _MY_ ears, the cassette version has more depth
and "space" (for lack of a better term) than the CD version, at least
_on the equipment I have_.

When I purchase a CD, I rip the songs onto my hard drive as MP3s. By
utilizing features of my sound card (SoundBlaster PCI512) I _ADD_ about
30% each of chorus and reverb to the audio. The resulting music sounds
better _to my ears_ than the plain (or "pure") audio.

My point is, everyone's ears are _different_. What sounds best to me may
sound so-so to someone else.

And so the battle rages on...

RoyalHeart

 

[[email protected]]

If you move LP noise onto CD to disguise the source for an AB test,
that will work fine if the surface noise has no impact on overall sound
quality, but I would very much expect that it has. Just as you can
sometimes improve perceived sound quality by introducing distortion by
modulating it at 50Hz, so you can change and sometimes even improve the
listening experience by adding noise.

If only it were as simple as cleanest is best, but it doesnt seem to
be.

So that leaves you to test a whole multitude of things, including CD
with and without added snap crackle and pop, vinyl in A1 condition with
no crackle and so on. No doubt the ABCDEFGHIJ tester will simply be
confused!


NT

 

[gwhite]

If you move LP noise onto CD to disguise the source for an AB test,
that will work fine if the surface noise has no impact on overall sound
quality, but I would very much expect that it has.

That "it does" have an impact was exactly his point. So is your point
that CD's "sound better" if LP noise is added? If so, I smell a market
for "noised up" CD's, since it would be cheaper to make CD's noisy (with
LP noise), than to mess with LP's themselves. How about a knob on the
amp, right beside the bass control that says "LP noise?"

Just as you can
sometimes improve perceived sound quality by introducing distortion by
modulating it at 50Hz,...

Are you claiming that one can "improve perceived sound quality" by
creating distortion, and then modulating that distortion with 50 Hz"
Please explain, because it sounds strange. I have never heard of such
an "enhancement" technique in hi-fi systems.

... so you can change and sometimes even improve the
listening experience by adding noise.

Why would that be so?

If only it were as simple as cleanest is best, but it doesnt seem to
be.

"Cleanest is best" is pretty much the definition of hi-fi. So if you
want to add distortion, you need to explain why you think it helps. Are
you saying you don't like the mix/production of the source material and
distortion will make ot better? That's fine if you do, but that is not
the definition of hi-fi, which seeks to minimize coloration by
definition. That is, it tracks the source with *high fidelity*.

So that leaves you to test a whole multitude of things, including CD
with and without added snap crackle and pop, vinyl in A1 condition with
no crackle and so on. No doubt the ABCDEFGHIJ tester will simply be
confused!

I suppose an LP without these impairments is exceedingly rare, if it
exists at all. This is the common reason of why the tester will be
confused. That is exactly the point and why it is suggested as a test.

If your argument is for a lab instrumentation grade LP and player that
only white-coated lab rats in a clean room see, then you can afford the
same hedge to the CD: give it 24 bits and a 200 k sampling rate.

 

[gwhite]

If you had offerd a convincing argument for there being no detectable
difference between how valves and trs sound, I'd say you had a
conclusion well worth considering, but you've offerd not a single jot
of evidence for such here.

As far as hi-fi goes, the claims are typically made by the toob
aficionados, not the other way around. So it is up to them to
rationally explain (and provide evidence for) the claim. Ban is simply
reciting common claims -- he didn't pull them out of thin air.

For creating music and particularly for electric guitar, the amp is part
of the instrument, so any hi-fi arguments are void there.

If you seek to add distortion to your *reproduction* system via toob
distortion, then that's your business. Doing so simply means you think
the original production needed more distortion. That's okay, but it is
by definition departing from the meaning of "hi-fi."

I adjust graphic equalizers sometimes because I don't like the tone
balance of the original source. But that is, a linear operation (as far
as not creating new frequency products), not a non-linear one like
adding distortion.

 

[Ban]

I have here some recordings by a group called Sphongle, where kind of phono
style crackling noises have been added deliberately in a few passages. These
immediately sound much more "spacy" than clean parts. Can it have to do with
the capacity of our hearing system to locate cracks very fast and precise?
Imagine, that it once was a criterion to survive, when you could avoid being
attacked by wild animals or Native American warriors.
The wide frequency range of a "crackle" will give us easyly to identify and
process clues about the environment, just as a blind man snaps his fingers
or tongue to get usable echoes for visualisation. And the "space" feeling
comes from the room response during playback, not from echoes recorded on
the disk, as you can see with overdamped rooms which sound unnaturally dry
and lifeless.

A particulary stupid way of argumentation is mocking, Mr.cat. Maybe your
capacity to understand is low, but we said we wanted to compare the phono
record to a home made CD of that same record played from the same rig. There
are only these two feeds, which I bet you will not be able to consistently
tell apart.

I own both the cassette tape (remember those?) and CD version of "The
Divine Bette Midler." To _MY_ ears, the cassette version has more
depth and "space" (for lack of a better term) than the CD version, at
least _on the equipment I have_.

Same as before, added noise can improve the listening experience giving it
this "lifelike" touch, which phono-lovers always complain is missing in
digital recordings.

Good listening

 

[[email protected]]

[email protected] wrote:

That "it does" have an impact was exactly his point. So is your point
that CD's "sound better" if LP noise is added?

not my point at all.

Are you claiming that one can "improve perceived sound quality" by
creating distortion,

in some cases yes

and then modulating that distortion with 50 Hz"
no


Please explain, because it sounds strange. I have never heard of such
an "enhancement" technique in hi-fi systems.

A technique I used on lofi is to modulate the signal by 50Hz. This does
not cause hum, as adding would, it causes a warmer sound with the
impression of much more bass. It is an effective way to address a
shortage of bass. This method was routinely used on old valve radios, I
guess unintentionally.

Why would that be so?

who knows

"Cleanest is best" is pretty much the definition of hi-fi. So if you
want to add distortion, you need to explain why you think it helps.

Take a track and play with effects and types of distortion. Its not
hard to find music that sounds better with effects added. Its also not
hard to see that some distortion can give a diffrent feel to the music:
eg 50Hz modulation, sot clipping etc all give a different character to
it.
Its also fairly familiar territory that adding one distortion can
partuially make up for another distortion. Eg adding bass resonance can
somewhat compensate for inadequate bass response.

On the hifi scale the defects are smaller in magnitude, but there is no
reason to expect the same principles to not apply.

Are
you saying you don't like the mix/production of the source material and
distortion will make ot better?

I daresay thats so in some cases

That's fine if you do, but that is not
the definition of hi-fi, which seeks to minimize coloration by
definition. That is, it tracks the source with *high fidelity*.

yes and no. High fidelity does not equal perfect fidelity IRL. With any
given budget you have to make choices between which imperfections you
prefer.

If it were really about minimising colouration, hfi amps wouldnt have
bass and treble controls. Nearly all do, for good reason.


NT

 

[[email protected]]

RoyalHeart wrote:

A particulary stupid way of argumentation is mocking, Mr.cat.

I'm assuming you did understand the argument that was made, and didnt
only notice the tongue in cheek comment at the end.

Maybe your
capacity to understand is low,

no, i wont comment

but we said we wanted to compare the phono
record to a home made CD of that same record played from the same

rig.

yes, so? I take it you do understand I was making a different point to
yours.


NT

 

[[email protected]]

[email protected] wrote:

Ban is simply
reciting common claims -- he didn't pull them out of thin air.

He caimed that I believed xyz, which was pulled out of the air, and
perhaps underconsidered. His further post indicates his ego has not yet
recovered from this mistake, and he wishes to take it out on me. Today
I dont feel like letting him.

For creating music and particularly for electric guitar, the amp is part
of the instrument, so any hi-fi arguments are void there.

If you seek to add distortion to your *reproduction* system via toob
distortion, then that's your business. Doing so simply means you think
the original production needed more distortion. That's okay, but it is
by definition departing from the meaning of "hi-fi."

only if you think perfection is attainable, and desirable. In reality
no kit is perfect, so one has to choose between one set of distortions
and another. If that werent so, all hifi kit would be the same in terms
of sound quality. But its not.


NT

 

[gwhite]

In reality no kit is perfect,...
Obviously.

... so one has to choose between one
set of distortions and another.

The meaning of hi-fi is by definition choosing the lowest distortion.
No one claims there is such a thing as "no distortion."

 

[gwhite]

not my point at all.

Okay, I get it: it is simply a logical conclusion.

in some cases yes

A technique I used on lofi is to modulate the signal by 50Hz. This does
not cause hum, as adding would, it causes a warmer sound with the
impression of much more bass.

You're simpy translating all frequencies by 50 Hz, and presumably adding
this to the original signal in some proportion. What is the technical
definition of "warm?" I don't have any idea what it means in a
quantifiable sense.

It is an effective way to address a
shortage of bass.

I would approach this problem differently: I would use a speaker with
improved bass response, or short of that, turn up the bass control.

This method was routinely used on old valve radios, I
guess unintentionally.

If it wasn't intentional, then it's not a "method."

Take a track and play with effects and types of distortion. Its not
hard to find music that sounds better with effects added.

That is not hi-fi, and listener response may be, and probably is, random
across many listeners. So I have no way to comment.

For me, this topic is not about subjective favorites of individuals
within and across large populations.

Its also not
hard to see that some distortion can give a diffrent feel to the music:
eg 50Hz modulation, sot clipping etc all give a different character to
it.

Sure, you can make it sound profoundly different. But again, that is
not the goal of a hi-fi amplifier.

Just to be clear, the goal in amplification is transparency. That is,
push all classes of distortion, even "linear distortion" to levels not
detectable by humans.

Its also fairly familiar territory that adding one distortion can
partuially make up for another distortion.

I am quite familiar with the concept of predistortion in the radio
communications field. In that field, the predistortion processing is
specifically implemented to _explicitly_ cancel (null) distortion
products occurring *later* in the chain. This nulling is not what is
done in audio work, and nor is the technique of predistortion necessary
in audio work, since traditional methods of distortion control are
sufficient. (I'm talking about Volterra-Wiener polynomial type
distortion/modeling. The null parameters are acquired via behavioral
modeling.)

What I'm saying is that in audio work, one non-linear distortion is not
"making up for another distortion" in a way that has technical and
quantifiable meaning. It is simply an added (not nulling) non-linear
effect, and thus is not hi-fi, by definition. "Hi-fi" always seeks
lower distortion (to at least the point of inaudibility), not adding it,
unless the addition is in effect a nulling distortion (meaning lower
total distortion).

Eg adding bass resonance can
somewhat compensate for inadequate bass response.

Where are you adding this "bass resonance" into the system?

On the hifi scale the defects are smaller in magnitude, but there is no
reason to expect the same principles to not apply.

Principles may indeed apply in theory, but the question is whether the
defects are audible to humans and are thus quantifiable. This is where
those who claim superiority of tube hi-fi amplification over transistor
amplification always fall short of scientific standards. At least I am
not aware of any convincing studies confirming the claim. To be fair,
the dearth of good studies in the past and the ubiquitous nature of
non-scientific lingo permeating the field make me cease looking. I felt
that if it was that hard to ascertain the differences, they must be so
small as to be irrelevent for most situations and most listeners. If
there have been breakthroughs in the past 10 years, I am not aware of
them because I'm not really looking.

Are you saying you don't like the mix/production
of the source material and [adding]
distortion will make it better?

I daresay thats so in some cases

I think the difficulty with using an amplifier unit as a non-linear
distortion adder/processor is that it is not very controllable. That
is, a hi-fi amp is designed to *not* distort, not to distort. Different
distortion levels will be highly dependent on the volume level -- that
is, volume is not independent of distortion. I could not call this a
good audio processing design by any engineering standards I am familiar
with.

yes and no. High fidelity does not equal perfect fidelity IRL.

Of course. But let's not lose sight of the problem definition of hi-fi:
lower distortion to inaudible levels.

With any given budget you have to
make choices between which imperfections you
prefer.

As it goes in the hi-fi reproduction chain, electronic amplification is
the easiest and therefore cheapest dragon to slay. I predict most of
the important power amplifier work in the future (it is already well
started) will have to do with getting power/energy/size/weight efficient
designs up to the hi-fi standards and low cost of the more traditional
approaches. That's my opinion, anyway.

If it were really about minimising colouration, hfi amps wouldnt have
bass and treble controls. Nearly all do, for good reason.

At worst, tone controls produce "linear distortion." They do not add
spectral energy not already present in the source, unlike the non-linear
distortion generated by amplifiers. Moreover, tone adjustment may have
little to do with the source material, but may be _directly_ *nulling* a
deficiency in, for example, a speaker system, since quality speakers can
represent a major fraction of hi-fi system cost. They may also be
compensating for the listening room problems, and not the source.
Again, this is an example of a nulling situation.

Yes, tone controls may be (and are, of course) used to explicitly alter
the spectral balance of the _source_ depending upon listener
preference. However, this is acknowledged as a specific processing
task, not an amplification task. Audible non-linear distortion products
are a no-no for a box that is said to be simply a spectral balance
processor. Perhaps the same should be true for an amplifier: "just
amplify."

The delineation of tonal processing (or any other processing) from
amplification is logical. However, combining power amplification with
non-linear distortion destroys this separation.

The complete separation of variables is possible for tonal processing;
most importantly is the separation of tonal processing from volume
(average power level), although some iteration will be necessary. This
is not so for the power amplifier (or even preamp?) which also used as a
distortion adder ("distortion processor"). Volume and distortion are
not separable. That is not a good design.

In short, if someone wants to add distortion or alter the tone, then
that's their choice and subjective valuation. I could not argue with
that. But adding non-nulling non-linear distortion is plainly not
hi-fi, by definition. Only in the case where an added distortion
explicitly nulls another can an added distortion be said to be "hi-fi."
The linear distortion of tone controls partially compensating (nulling)
the response of deficient speakers can be said to be such a case, and so
remains in the realm of hi-fi. _Masking_ (rather than nulling) one
distortion by introduction of another is not hi-fi. Also, the claimed
merits of masking non-linear distortions have remained in the realm of
claim, not proven fact, as best I know. Of course, if someone wants to
do it and pay their own money to do it, why would I care?

During some long conversations, I once said to a friend that he thought
of his "hi-fi" tube amp as as much of a non-linear processor as he did
an amp. He agreed. I then explained to him why the non-linear
processing was not easily separable from other system parameters. He
had to think about that. For all I know, he still is thinking about it.

 

[[email protected]]

[email protected] wrote:

Lets start by quoting you on this, since it really is the key point
imho:

Obviously.

bear this in mind in all of the below.


That is an inevitable logical conclusion from the above I think.

The meaning of hi-fi is by definition choosing the lowest distortion.
No one claims there is such a thing as "no distortion."

I would suggest that is an unrealistic definition. Hifi buffs have not
generally claimed that lowest paper distortion spec is what sounds
best.

It is well known different types of distortion sound different,
therefore it is elementary to conclude that the amp with the lowest THD
is not guaranteed to be the one that sounds best.

Okay, I get it: it is simply a logical conclusion.

is it? why?

You're simpy translating all frequencies by 50 Hz, and presumably adding
this to the original signal in some proportion.
yup.


What is the technical
definition of "warm?"

no idea if there even is one. Trying it and seeing soon answers the
question in a practical way.

I don't have any idea what it means in a
quantifiable sense.


I would approach this problem differently: I would use a speaker with
improved bass response, or short of that, turn up the bass control.

missing the point. In the real world many cut price systems are used,
and it costs money to add bass boost, add speaker bass response, and
add amp power capacity to be able to run it. Given that cut price
systems are used, the logical thing to do with them is maximise their
abilities. This can be done at apx no cost by injecting mains junk into
the amp.

If it wasn't intentional, then it's not a "method."
If



That is not hi-fi,

and listener response may be, and probably is, random
across many listeners.

Its really not. The 50Hz modulation method gets fairly consistent
responses from listeners. The contrast between 2nd and 3rd harmonic
distortion might also be, though I cant be sure. I really see no reason
to think its inconsistent.

So I have no way to comment.

For me, this topic is not about subjective favorites of individuals
within and across large populations.


Sure, you can make it sound profoundly different. But again, that is
not the goal of a hi-fi amplifier.

Just to be clear, the goal in amplification is transparency. That is,
push all classes of distortion, even "linear distortion" to levels not
detectable by humans.

Whether that goal is achieved is another question. Many will argue that
its not. If its not, we are indeed comparing one set of distortions
with another, in a world of not quite ideal amplifiers, and the one
with the most euphonic set of distortions wins.

I am quite familiar with the concept of predistortion in the radio
communications field. In that field, the predistortion processing is
specifically implemented to _explicitly_ cancel (null) distortion
products occurring *later* in the chain.

Right, but thats a different concept to the one I was talking about. I
was talking about things like eg adding 50Hz modulation to partially
make up for lack of bass, and suggesting the same concept of
semi-compensation occurs with distortions present in much lower
percentages, ie in hifi amps.

This nulling is not what is
done in audio work, and nor is the technique of predistortion necessary
in audio work, since traditional methods of distortion control are
sufficient. (I'm talking about Volterra-Wiener polynomial type
distortion/modeling. The null parameters are acquired via behavioral
modeling.)

What I'm saying is that in audio work, one non-linear distortion is not
"making up for another distortion" in a way that has technical and
quantifiable meaning.

I think its well demonstrated.

It is simply an added (not nulling) non-linear
effect, and thus is not hi-fi, by definition. "Hi-fi" always seeks
lower distortion (to at least the point of inaudibility), not adding it,
unless the addition is in effect a nulling distortion (meaning lower
total distortion).

if that were true, one would simply look at the THD of amps, pick the
lowest, and that would be it, youd get best sound. Real life doesnt
work like that.

I bring up the subject of lo-fi a lot in this because with larger
levels of distortion it is extremely easy to see the effects, and thus
the concepts in action. It is easy to take a basic 0.5w amp, with
inadequate bass, and add 50Hz modulation. It is easy to compare 3rd
harmonic with 2nd when youre running at 2% distortion, not 0.002%. etc.

Lots of people are familiar with the 50Hz modulation trick, though most
dont realise thats how its done.

Where are you adding this "bass resonance" into the system?

In a lo-fi one would usally add it at the speaker, with underdamped
mechanical resonance(s). In principle one can add these things
anywhere.

Principles may indeed apply in theory, but the question is whether the
defects are audible to humans and are thus quantifiable.

Certainly thats another valid question. Im not sure its one we can
asnwer in this thread though.

This is where
those who claim superiority of tube hi-fi amplification over transistor
amplification always fall short of scientific standards. At least I am
not aware of any convincing studies confirming the claim. To be fair,
the dearth of good studies in the past and the ubiquitous nature of
non-scientific lingo permeating the field make me cease looking.

ignorance and unscience permeate most fields. That only means its not
worth looking in the places where one finds no science. It doesnt make
a field invalid.

I felt
that if it was that hard to ascertain the differences, they must be so
small as to be irrelevent for most situations and most listeners.

This is why I keep mentioning lo-fi. With lo-fi you can turn the
distortion levels right up, and the results are immediate and obvious.

If
there have been breakthroughs in the past 10 years, I am not aware of
them because I'm not really looking.

Are you saying you don't like the mix/production
of the source material and [adding]
distortion will make it better?

I daresay thats so in some cases

I think the difficulty with using an amplifier unit as a non-linear
distortion adder/processor is that it is not very controllable. That
is, a hi-fi amp is designed to *not* distort, not to distort. Different
distortion levels will be highly dependent on the volume level -- that
is, volume is not independent of distortion. I could not call this a
good audio processing design by any engineering standards I am familiar
with.

this is really missing the point that no amp is in reality distortion
free. Any good designer is handling distortion: no-one has yet found a
way to the 0% amp.

Of course. But let's not lose sight of the problem definition of hi-fi:
lower distortion to inaudible levels.

I would suggest changing your definition. That may have been good when
the term was coined.

As it goes in the hi-fi reproduction chain, electronic amplification is
the easiest and therefore cheapest dragon to slay.

Amplifier distortion has not been brought down to 0% yet, the dragon
has not been slayed. Easiest to make good maybe, but to eliminate all
problems from, no.

I predict most of
the important power amplifier work in the future (it is already well
started) will have to do with getting power/energy/size/weight efficient
designs up to the hi-fi standards and low cost of the more traditional
approaches. That's my opinion, anyway.

me too. Also I think more amplifier classes will come along with better
efficiency, cost, or other advantages. I worked on a design that
shifted the heat diss away from the output trs, but unfortunately it
did not in the end enable any less silicon to be used.

At worst, tone controls produce "linear distortion." They do not add
spectral energy not already present in the source, unlike the non-linear
distortion generated by amplifiers. Moreover, tone adjustment may have
little to do with the source material, but may be _directly_ *nulling* a
deficiency in, for example, a speaker system, since quality speakers can
represent a major fraction of hi-fi system cost.

But in reality they do not correct such defects. A look at any
commercial speaker's response curve shows it can not be corrected with
a bass or treble control.

These controls will lessen the infidelity in some areas of the
spectrum, while worsening it in others. IOW the control's frequency
response does not match the speaker's.

They may also be
compensating for the listening room problems, and not the source.
Again, this is an example of a nulling situation.

not usually.

Yes, tone controls may be (and are, of course) used to explicitly alter
the spectral balance of the _source_ depending upon listener
preference. However, this is acknowledged as a specific processing
task, not an amplification task. Audible non-linear distortion products
are a no-no for a box that is said to be simply a spectral balance
processor.

Im sorry but theyre inevitable. Its thus meaningless to say theyre a
no-no. Theyre an inevitable which must be handled.

Perhaps the same should be true for an amplifier: "just
amplify."

maybe one day that will be reality.

The delineation of tonal processing (or any other processing) from
amplification is logical. However, combining power amplification with
non-linear distortion destroys this separation.

The complete separation of variables is possible for tonal processing;
most importantly is the separation of tonal processing from volume
(average power level), although some iteration will be necessary. This
is not so for the power amplifier (or even preamp?) which also used as a
distortion adder ("distortion processor"). Volume and distortion are
not separable. That is not a good design.

It is part of every amplifier design on the planet, good and bad alike.
There is no 0% distortion stage.

In short, if someone wants to add distortion or alter the tone, then
that's their choice and subjective valuation. I could not argue with
that. But adding non-nulling non-linear distortion is plainly not
hi-fi, by definition.

It is normal in amp design, and is used to lower overall distortion,
but not cancel it.

Only in the case where an added distortion
explicitly nulls another can an added distortion be said to be "hi-fi."
The linear distortion of tone controls partially compensating (nulling)
the response of deficient speakers can be said to be such a case, and so
remains in the realm of hi-fi.

I think that describes graphic equalisers, not tone controls.


NT

 

[[email protected]]

[email protected] wrote:

Lets start by quoting you on this, since it really is the key point
imho:

Obviously.

bear this in mind in all of the below.


That is an inevitable logical conclusion from the above I think.

The meaning of hi-fi is by definition choosing the lowest distortion.
No one claims there is such a thing as "no distortion."

I would suggest that is an unrealistic definition. Hifi buffs have not
generally claimed that lowest paper distortion spec is what sounds
best.

It is well known different types of distortion sound different,
therefore it is elementary to conclude that the amp with the lowest THD
is not guaranteed to be the one that sounds best.

Okay, I get it: it is simply a logical conclusion.

is it? why?

You're simpy translating all frequencies by 50 Hz, and presumably adding
this to the original signal in some proportion.
yup.


What is the technical
definition of "warm?"

no idea if there even is one. Trying it and seeing soon answers the
question in a practical way.

I don't have any idea what it means in a
quantifiable sense.


I would approach this problem differently: I would use a speaker with
improved bass response, or short of that, turn up the bass control.

missing the point. In the real world many cut price systems are used,
and it costs money to add bass boost, add speaker bass response, and
add amp power capacity to be able to run it. Given that cut price
systems are used, the logical thing to do with them is maximise their
abilities. This can be done at apx no cost by injecting mains junk into
the amp.

If it wasn't intentional, then it's not a "method."
If



That is not hi-fi,

and listener response may be, and probably is, random
across many listeners.

Its really not. The 50Hz modulation method gets fairly consistent
responses from listeners. The contrast between 2nd and 3rd harmonic
distortion might also be, though I cant be sure. I really see no reason
to think its inconsistent.

So I have no way to comment.

For me, this topic is not about subjective favorites of individuals
within and across large populations.


Sure, you can make it sound profoundly different. But again, that is
not the goal of a hi-fi amplifier.

Just to be clear, the goal in amplification is transparency. That is,
push all classes of distortion, even "linear distortion" to levels not
detectable by humans.

Whether that goal is achieved is another question. Many will argue that
its not. If its not, we are indeed comparing one set of distortions
with another, in a world of not quite ideal amplifiers, and the one
with the most euphonic set of distortions wins.

I am quite familiar with the concept of predistortion in the radio
communications field. In that field, the predistortion processing is
specifically implemented to _explicitly_ cancel (null) distortion
products occurring *later* in the chain.

Right, but thats a different concept to the one I was talking about. I
was talking about things like eg adding 50Hz modulation to partially
make up for lack of bass, and suggesting the same concept of
semi-compensation occurs with distortions present in much lower
percentages, ie in hifi amps.

This nulling is not what is
done in audio work, and nor is the technique of predistortion necessary
in audio work, since traditional methods of distortion control are
sufficient. (I'm talking about Volterra-Wiener polynomial type
distortion/modeling. The null parameters are acquired via behavioral
modeling.)

What I'm saying is that in audio work, one non-linear distortion is not
"making up for another distortion" in a way that has technical and
quantifiable meaning.

I think its well demonstrated.

It is simply an added (not nulling) non-linear
effect, and thus is not hi-fi, by definition. "Hi-fi" always seeks
lower distortion (to at least the point of inaudibility), not adding it,
unless the addition is in effect a nulling distortion (meaning lower
total distortion).

if that were true, one would simply look at the THD of amps, pick the
lowest, and that would be it, youd get best sound. Real life doesnt
work like that.

I bring up the subject of lo-fi a lot in this because with larger
levels of distortion it is extremely easy to see the effects, and thus
the concepts in action. It is easy to take a basic 0.5w amp, with
inadequate bass, and add 50Hz modulation. It is easy to compare 3rd
harmonic with 2nd when youre running at 2% distortion, not 0.002%. etc.

Lots of people are familiar with the 50Hz modulation trick, though most
dont realise thats how its done.

Where are you adding this "bass resonance" into the system?

In a lo-fi one would usally add it at the speaker, with underdamped
mechanical resonance(s). In principle one can add these things
anywhere.

Principles may indeed apply in theory, but the question is whether the
defects are audible to humans and are thus quantifiable.

Certainly thats another valid question. Im not sure its one we can
asnwer in this thread though.

This is where
those who claim superiority of tube hi-fi amplification over transistor
amplification always fall short of scientific standards. At least I am
not aware of any convincing studies confirming the claim. To be fair,
the dearth of good studies in the past and the ubiquitous nature of
non-scientific lingo permeating the field make me cease looking.

ignorance and unscience permeate most fields. That only means its not
worth looking in the places where one finds no science. It doesnt make
a field invalid.

I felt
that if it was that hard to ascertain the differences, they must be so
small as to be irrelevent for most situations and most listeners.

This is why I keep mentioning lo-fi. With lo-fi you can turn the
distortion levels right up, and the results are immediate and obvious.

If
there have been breakthroughs in the past 10 years, I am not aware of
them because I'm not really looking.

Are you saying you don't like the mix/production
of the source material and [adding]
distortion will make it better?

I daresay thats so in some cases

I think the difficulty with using an amplifier unit as a non-linear
distortion adder/processor is that it is not very controllable. That
is, a hi-fi amp is designed to *not* distort, not to distort. Different
distortion levels will be highly dependent on the volume level -- that
is, volume is not independent of distortion. I could not call this a
good audio processing design by any engineering standards I am familiar
with.

this is really missing the point that no amp is in reality distortion
free. Any good designer is handling distortion: no-one has yet found a
way to the 0% amp.

Of course. But let's not lose sight of the problem definition of hi-fi:
lower distortion to inaudible levels.

I would suggest changing your definition. That may have been good when
the term was coined.

As it goes in the hi-fi reproduction chain, electronic amplification is
the easiest and therefore cheapest dragon to slay.

Amplifier distortion has not been brought down to 0% yet, the dragon
has not been slayed. Easiest to make good maybe, but to eliminate all
problems from, no.

I predict most of
the important power amplifier work in the future (it is already well
started) will have to do with getting power/energy/size/weight efficient
designs up to the hi-fi standards and low cost of the more traditional
approaches. That's my opinion, anyway.

me too. Also I think more amplifier classes will come along with better
efficiency, cost, or other advantages. I worked on a design that
shifted the heat diss away from the output trs, but unfortunately it
did not in the end enable any less silicon to be used.

At worst, tone controls produce "linear distortion." They do not add
spectral energy not already present in the source, unlike the non-linear
distortion generated by amplifiers. Moreover, tone adjustment may have
little to do with the source material, but may be _directly_ *nulling* a
deficiency in, for example, a speaker system, since quality speakers can
represent a major fraction of hi-fi system cost.

But in reality they do not correct such defects. A look at any
commercial speaker's response curve shows it can not be corrected with
a bass or treble control.

These controls will lessen the infidelity in some areas of the
spectrum, while worsening it in others. IOW the control's frequency
response does not match the speaker's.

They may also be
compensating for the listening room problems, and not the source.
Again, this is an example of a nulling situation.

not usually.

Yes, tone controls may be (and are, of course) used to explicitly alter
the spectral balance of the _source_ depending upon listener
preference. However, this is acknowledged as a specific processing
task, not an amplification task. Audible non-linear distortion products
are a no-no for a box that is said to be simply a spectral balance
processor.

Im sorry but theyre inevitable. Its thus meaningless to say theyre a
no-no. Theyre an inevitable which must be handled.

Perhaps the same should be true for an amplifier: "just
amplify."

maybe one day that will be reality.

The delineation of tonal processing (or any other processing) from
amplification is logical. However, combining power amplification with
non-linear distortion destroys this separation.

The complete separation of variables is possible for tonal processing;
most importantly is the separation of tonal processing from volume
(average power level), although some iteration will be necessary. This
is not so for the power amplifier (or even preamp?) which also used as a
distortion adder ("distortion processor"). Volume and distortion are
not separable. That is not a good design.

It is part of every amplifier design on the planet, good and bad alike.
There is no 0% distortion stage.

In short, if someone wants to add distortion or alter the tone, then
that's their choice and subjective valuation. I could not argue with
that. But adding non-nulling non-linear distortion is plainly not
hi-fi, by definition.

It is normal in amp design, and is used to lower overall distortion,
but not cancel it.

Only in the case where an added distortion
explicitly nulls another can an added distortion be said to be "hi-fi."
The linear distortion of tone controls partially compensating (nulling)
the response of deficient speakers can be said to be such a case, and so
remains in the realm of hi-fi.

I think that describes graphic equalisers, not tone controls.


NT

 

[gwhite]

Lets start by quoting you on this, since it really is the key point
imho:



bear this in mind in all of the below.


That is an inevitable logical conclusion from the above I think.

Here's an analogy for you: it doesn't do any good for my FM receiver to
have a threshold sensitivity of -100dBm if the ambient noise is at -80
dBm.

IOW, if hi-fi amp distortion is below a threshold of audibility, then
it doesn't need to be lower or 0. Moreover, if two amps both have
distortion below a threshold of audibility, it doesn't matter if they
are characteristically different.

I would suggest that is an unrealistic definition. Hifi buffs have not
generally claimed that lowest paper distortion spec is what sounds
best.

I could not call them "hi-fi buffs if they aren't clear regarding what
hi-fi is. Yes, one needs to use caution in reading specifications. It
is likely that most of us in s.e.d are well aware of specsmanship games
played by vendors.

It is well known different types of distortion sound different,
therefore it is elementary to conclude that the amp with the lowest THD
is not guaranteed to be the one that sounds best.

The point of a hi-if element is to not "have it sound" at all. To have
it below an audible level is to say it has no sound. This is a separate
task from intentionally processing and coloring. There is nothing wrong
with coloring sound sources, but that is a task separate from hi-fi, and
one that should be explicit and independent.

I am not aware of any scientific study that conclusively shows that
humans can reliably detect different characteristic distortions under
0.5 to 1.0%, for as good or poor as the gross THD spec is (a "paper
spec," as you rightly call it). I could never make the claim that
"different types of distortion sound different" because I am aware of no
evidence that such a statement is true *in general*. By "in general," I
mean allow for specific exclusions (guitar amps operating with high
distortion are perhaps a good example).

is it? why?

The same processing was used, a processing claimed to be superior by LP
fans.

sequence:
1. LP claimed to sound better than CD, for same master source
2. Copy LP to CD
3. listener can't tell the difference between LP and LP copied to CD
4. If #1 and #3 are both true, then it is a logical conclusion

no idea if there even is one. Trying it and seeing soon answers the
question in a practical way.

But perhaps you're saying the technical definition of warm is your 50 Hz
mod system.

This is s.e.d. Since engineers deal in applied science in designing
electronics, a scientific goal definition must be made. Otherwise,
there is nothing to work with.

missing the point. In the real world many cut price systems are used,
and it costs money to add bass boost, add speaker bass response, and
add amp power capacity to be able to run it. Given that cut price
systems are used, the logical thing to do with them is maximise their
abilities. This can be done at apx no cost by injecting mains junk into
the amp.

Even $50 boom boxes have bass boost and tone controls. What is the
price range you're looking for? Incidentally, I think most tube
audiophile gear is on the other end of the spectrum -- they should be
able to afford tone controls.

???



Its really not. The 50Hz modulation method gets fairly consistent
responses from listeners.

Evidence?

One must question why, if a positive and significant positive listening
response is shown across large populations, why this apparently
inexpensive enhancement is not more commonplace. Why isn't there a
"warm" knob on cheap, mid, and high priced gear? It's absence is very
puzzling for such a clear claimed inexpensive enhancement.

The contrast between 2nd and 3rd harmonic
distortion might also be, though I cant be sure. I really see no reason
to think its inconsistent.

I would have to see a good study, since there would seem to be no reason
to assume uniformity or even consistancy.

Whether that goal is achieved is another question. Many will argue that
its not.

To my knowledge, there is no double-blind evidence that people can
reliably detect the low distortions commonly available in today's hi-fi
power amps. It is one matter to buy what one likes, for whatever
reason. It is another to make general scientific claims about human
hearing.

Also, the ancedotal evidence, for myself, and the mass of people I know,
is they (and I) can't make quality distinctions between amps with low
distortion content. Thus the lack of scientific evidence by those who
claim ability to detect differences at these low levels, combined with
the anecdotal evidence, leads me to remain skeptical of the claims. I
have no reason to believe it. It *may* be true, but the evidence is
entirely missing.

If its not, we are indeed comparing one set of distortions
with another, in a world of not quite ideal amplifiers, and the one
with the most euphonic set of distortions wins.

Well in my world that wouldn't be so. I would pick the cheapest with
distortion low enough such that I couldn't detect the difference between
the cheapest one and another one that cost $1 more (certeris paribus).
That is, I don't care what the distortion is in either one, if I can't
detect it, and like we learned in ECON101, all decisions are made at the
margin.

Right, but thats a different concept to the one I was talking about. I
was talking about things like eg adding 50Hz modulation to partially
make up for lack of bass, and suggesting the same concept of
semi-compensation occurs with distortions present in much lower
percentages, ie in hifi amps.

Basically you are talking about masking. It is similar in a sense to
the lossy compression of mp3. Where some of the sound content
sufficiently masks other content, the content that is masked can be
dispensed with.

This is a processing that you believe sounds nice. That's fine, but it
has little to do with hi-fi.

I think its well demonstrated.

To my knowledge, it has not been demonstrated.

if that were true, one would simply look at the THD of amps, pick the
lowest, and that would be it, youd get best sound. Real life doesnt
work like that.

I bring up the subject of lo-fi a lot in this because with larger
levels of distortion it is extremely easy to see the effects, and thus
the concepts in action. It is easy to take a basic 0.5w amp, with
inadequate bass, and add 50Hz modulation.

The problem isn't inadequate bass, per se, it is insufficient power.

It is easy to compare 3rd harmonic with 2nd
when youre running at 2% distortion, not 0.002%. etc.

This is exactly the crux of the matter. You, as best I can tell here,
believe that because distortion is audible and distinguishable at higher
levels, it is audible and distinguishable at lower levels, but just at
some scaled down version.

There is no scientific reason to presuppose this sort of linear level
transposition of distortion audibility in human hearing. Nature is
replete with examples of non-linear responses (including threshold
effects) by living creatures to environmental phenomena. Perhaps the
window response of humans to many phamaceuticals is a good and
well-known example of non-linear response.

In short, there is zero evidence that I am aware of that would
demonstrate that humans do *not* have thresholds in their ability to
hear subtle differences in sounds. The instrument of the ear may indeed
be "sensitive," but that does not equate to infinite sensitivity, nor a
linear response in sensitivity.

Lots of people are familiar with the 50Hz modulation trick, though most
dont realise thats how its done.

You're posting to s.e.d. Most know how modulation is performed. If
they don't, they are probably a bit out of place here.

In a lo-fi one would usally add it at the speaker, with underdamped
mechanical resonance(s). In principle one can add these things
anywhere.

This is a compensation nulling (and to some measure imperfect) of
another hi-fi shortcoming. It is not a masking.

Certainly thats another valid question. Im not sure its one we can
asnwer in this thread though.


ignorance and unscience permeate most fields. That only means its not
worth looking in the places where one finds no science. It doesnt make
a field invalid.

Well sure. But the fact of life is we only have so many resources.
Basically there is no low-hanging fruit left to pick when it comes to
amplifier distortion. Today's hi-fi fan who commands even a modest
income can get a low distortion and high power amp for fairly low cost
in real dollars. This is another way of saying _it isn't worth
pursuing_ in nearly all cases.

The fact that the "audibility question" is not "one we can answer in
this thread," and about a billion others sends us the message of severe
doubt when it comes to valuation of extreme efforts in simply proving or
disproving these marginal claims regarding amplifier distortion in hi-fi
amps. Information can be expensive at times. In this case, the
information is not worth the cost of procurement, as best I've been able
to tell.

This is why I keep mentioning lo-fi. With lo-fi you can turn the
distortion levels right up, and the results are immediate and obvious.

Again, this is apparently an assumption of transposition of audibility.
There is no reason to presuppose this that I am aware of.

If
there have been breakthroughs in the past 10 years, I am not aware of
them because I'm not really looking.

Are you saying you don't like the mix/production
of the source material and [adding]
distortion will make it better?

I daresay thats so in some cases

I think the difficulty with using an amplifier unit as a non-linear
distortion adder/processor is that it is not very controllable. That
is, a hi-fi amp is designed to *not* distort, not to distort. Different
distortion levels will be highly dependent on the volume level -- that
is, volume is not independent of distortion. I could not call this a
good audio processing design by any engineering standards I am familiar
with.

this is really missing the point that no amp is in reality distortion
free. Any good designer is handling distortion: no-one has yet found a
way to the 0% amp.

More importantly, there is no reason to assume such a thing is
necessary, for any practical purpose of hi-fi listeners.

I would suggest changing your definition. That may have been good when
the term was coined.

No, the thing to do would be to dispense with the term "hi-fi"
altogether rather than promote an oxymoron that obliterates our
language. But who can command people to lose interest in hi-fi? Why
would anyone do such a thing?

Amplifier distortion has not been brought down to 0% yet, the dragon
has not been slayed. Easiest to make good maybe, but to eliminate all
problems from, no.

If people can't hear it, and to my knowledge they can't, it has been
slayed. There is no reason to presume a "need" for a zero level of
distortion. That would be a solution in search of a problem.

me too. Also I think more amplifier classes will come along with better
efficiency, cost, or other advantages. I worked on a design that
shifted the heat diss away from the output trs, but unfortunately it
did not in the end enable any less silicon to be used.


But in reality they do not correct such defects. A look at any
commercial speaker's response curve shows it can not be corrected with
a bass or treble control.

Not completely, that is certainly true. But no claim of perfection was
made. A *partial* compensation was affordably provided. A less
affordable solution such as a graphic equalizer will do a better job.
Life, and hi-fi, are about tradeoffs.

These controls will lessen the infidelity in some areas of the
spectrum, while worsening it in others. IOW the control's frequency
response does not match the speaker's.

Obviously. The question for the user is the mix they deem optimal; that
would be balancing the defects as best they can. The designer simply
allows them a measure of choice in determining that mix for the local
situation.

not usually.


Im sorry but theyre inevitable. Its thus meaningless to say theyre a
no-no. Theyre an inevitable which must be handled.

Oh, it is definitely a no-no.

maybe one day that will be reality.

Regarding scientifically *demonstrable* human ability to detect
distortion, it is a reality and has been for some time. Sure, some
folks *claim* ability to hear minute levels of distortion, but they
haven't been able to demonstrate it.

Maybe they can detect it, but who else cares since the information to
really know is exceedingly expensive? It is probably cheaper for those
who make these claims to simply buy the stuff they believe is best than
to prove the matter scientifically. But this is *sci* electronics
design. Without science, it is irrelevent here.

IMO, the people who make these claims should stop making claims they
can't prove. They should simply say it is their belief. Then their
subjective wants, and real purchases are based on those beliefs, can be
made and no rational justification is needed. Doing so would remove the
rationality aspect; they would not need to attempt defending what has
been an intractable problem given the cost of good information. Just
treat it like religion: people can beleive what they want if it doesn't
hurt anybody else. What do I care if someone pays $3k for a 50 watt
tube amp? I could not care less.

It is part of every amplifier design on the planet, good and bad alike.
There is no 0% distortion stage.

There is no evidence that the fact of non-zero distortion is relevent to
human hearing. There is no necessary linkage.

It is normal in amp design, and is used to lower overall distortion,
but not cancel it.

There is a better way to phrase the distortion control techniques in
audio amps. The intent is certainly to *cancel* distortion, and in fact
this is what is done. It is only that it cannot be "done" in the
absolute (zeroed) -- it cannot *totally* cancel it. To say it is
lowered is indeed to say it is cancelled or controlled *to a measure*.

I think that describes graphic equalisers, not tone controls.

You are correct. A bass an treble control are cheaper and don't provide
the precision of a graphic equalizer. That is explicitly why I used the
term "partially compensating," among others. For tonal adjustment, no
one claims absolute perfection any more than one claims amps have 0%
distortion.

 

[Kevin Aylward]

[email protected] wrote:

The point of a hi-if element is to not "have it sound" at all. To
have it below an audible level is to say it has no sound. This is a
separate task from intentionally processing and coloring. There is
nothing wrong with coloring sound sources, but that is a task
separate from hi-fi, and one that should be explicit and independent.

I am not aware of any scientific study that conclusively shows that
humans can reliably detect different characteristic distortions under
0.5 to 1.0%, for as good or poor as the gross THD spec is (a "paper
spec," as you rightly call it).

Well, I have no doubt whatsoever that 0.5% 2nd harmonic sounds different
from 0.5% 3rd. I don't see that as being debatable. Those sorts of test
have been done. Its imd that thats at issue as well. A 1k and 1.4k
generating a new 400hz at 0.5%,

You are actully way, way, out there on this.

See below before opening one mouth

I could never make the claim that
"different types of distortion sound different"

I can. Its trivially obvious. 2nd harmonic is twice the fundamental, so
a g harmonic sounds likes root g. 3rd harmonic is a d on top of the g.
You bet your booty you can hear that extra d if its large enough.

because I am aware of
no evidence that such a statement is true *in general*.

I am. There is plenty of evidence for that. Load and loads.

Download the files and listen mate. Hint, a 0.1% thd way worse then
12.5% thd

http://www.gedlee.com/distortion_perception.htm

You need to become a bit more aware, mate.

Kevin Aylward
[email protected]
http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
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