[Eeyore]

"Bob H." wrote:

So, let's see, will it be prejudice that wins or desire for a stunning sound ?

These probably do sound great with a transistor amp. But most are
87dbM/m with 4 ohm nominal impedance and who-knows-what impedance dips.
Also most have high-order crossovers pretty much right in the middle
of the vocal range.
A tube amp would have to be able to supply some power.
I'll stick with my Cornwalls (alinco), Hammer super 12's, and fostex
full rangers, and all their inherent evils. : )

Of course, they might sound ok in a small japanese apartment with a
tube amp.

I'll stick you down for the prejudice category then !

Full range speakers are a joke !

You're allowing your listening to be determined ( and minimised ) by obsolescent
practice.

Graham

[Eeyore]

"Bob H." wrote:

Whoops, I meant 87 db/M
87dbM/m with 4 ohm nominal impedance and who-knows-what impedance dips.

and alnico.
(alinco), Hammer super 12's, and fostex

Good God !

You think that Alnico magnets somehow produce superior sound over other magnets
? Is that lame or what ?

Graham

[Bob H.]

Full range speakers are a joke !

Oh, but they're a wonderful-sounding joke, and make me give me a sense
of satisfaction and relaxation while listening to music. Goosebumps
are regularly present.
Isn't that where we want to be in the end of it all?

And BTW, you speakers might sound great with tube amps. I never said
they wouldn't. They just have some characteristics I've found to be
detrimental with low power tube amplification. I could be completely
wrong. They could indeed sing.

Try them yourselves, and let me know if they do. You might need at
least 20 wpc to start with, however.

PS, one of my favourite amps is a Harmon Kardon SS amp. I still own it
today, and can't bear to part with it. I've got new sets of output
transistors, and one of these days I'll put them in and balance
them..... anyone have and ideas on how to replace the 100mf coupling
caps with something reasonable? They're the only signal caps in the
amplification chain, as far as I can see.

Man, Nora Jones just sounds better and better. Currenly on a 6em7 SE
amp, of which I disconnected the output iron, and kludged in a CF
circuit for my AKG headphones. I'm stuck in a hotel in Vancouver for a
couple of weeks. My source is my laptop, playing wave files through a
M-audio transit usb soundcard. There's a place called Lee's
Electronics which had some 3.3 mf Solens for a good price.
Highly recommended if in the area. They're really friendly, to boot.

DIY forever,
Bob H.



You're allowing your listening to be determined ( and minimised ) by obsolescent
practice.

Graham

[Bob H.]

It's just a quick way to date the speakers.

Why don't you buy an Emerson rack stereo and just get it over with? It
has all the specs you're looking for. You're obviously quite distrubed
with this whole tube audio thing.

Bob H.

[Bob Quintal]

wrote in
oups.com:


Bob Quintal wrote:
wrote in
oups.com:


Bob Quintal wrote:
Prune wrote in
4.76:

John Larkin
wrote in
:

http://www.eng.yale.edu/qlab/papers/.../PRL_shotnoise.
pdf

They call it "current noise" right in the abstract, as
the Vishay people do.

They can call it George. The mechanism by which the noise
is generated is that of shot noise. irregardless of the
name.

Why do you think that?

I think that because I've spent the last 30 years studying
the physics of electronic components, both active and
passive, in order to generate reliability assessments,
failure analyses, and other such administratrivia. The
summation of a shot noise profile and a Johnson noise profile
mirrors the measured results most closely.

Shot noise and Johnson noise are both "white" which is to say,
frequency independent.

What kind of noise profile lets you separate the two?

Voltage vs Time. given a resistor in thermal equiibrium, apply a
step increase to the current through the resistor. some noise
will follow the change in current instantly. additional noise
will track the Johnson noise expected from the change in
temperature generated by the change in current, which is not
instantaneous, but dependent on the ability of the substrate to
sink the additional heat generated by the current

If you are saying that you are seeing more white noise than
you'd expect from the resistance and temperature of your
device, you can't claim that the excess is shot noise - there
are other sources of white noise.

Yes, there are additional possibilities. Analysis of these
sources doesn't account for all observed behavious, therefore
some noise is shot noise.

I don't think that you have made your case.




--
Bob Quintal

PA is y I've altered my email address.

--
Posted via a free Usenet account from http://www.teranews.com

[[email protected]]

Bob Quintal wrote:
wrote in
oups.com:


Bob Quintal wrote:
wrote in
oups.com:


Bob Quintal wrote:
Prune wrote in
4.76:

John Larkin
wrote in
:

http://www.eng.yale.edu/qlab/papers/.../PRL_shotnoise.
pdf

They call it "current noise" right in the abstract, as
the Vishay people do.

They can call it George. The mechanism by which the noise
is generated is that of shot noise. irregardless of the
name.

Why do you think that?

I think that because I've spent the last 30 years studying
the physics of electronic components, both active and
passive, in order to generate reliability assessments,
failure analyses, and other such administratrivia. The
summation of a shot noise profile and a Johnson noise profile
mirrors the measured results most closely.

Shot noise and Johnson noise are both "white" which is to say,
frequency independent.

What kind of noise profile lets you separate the two?

Voltage vs Time. given a resistor in thermal equiibrium, apply a
step increase to the current through the resistor. some noise
will follow the change in current instantly. additional noise
will track the Johnson noise expected from the change in
temperature generated by the change in current, which is not
instantaneous, but dependent on the ability of the substrate to
sink the additional heat generated by the current

That could also be explained by hypothesising a range of thermal paths
to the substrate within the resistor - the less effectively heat-sunk
resistance paths would heat up faster and further.

If you are saying that you are seeing more white noise than
you'd expect from the resistance and temperature of your
device, you can't claim that the excess is shot noise - there
are other sources of white noise.

Yes, there are additional possibilities. Analysis of these
sources doesn't account for all observed behavious, therefore
some noise is shot noise.

You can't explain it any other way, so it has to be shot noise. Not all
that convincing.

--
Bill Sloman, Nijmegen

[[email protected]]

Hi Eyesore,

Your arrogance is no joke. You listen with your asshole. Sigh.

Try your ears, sometime.

Happy Ears!
Al


Eeyore wrote:

Full range speakers are a joke !

You're allowing your listening to be determined ( and minimised ) by obsolescent
practice.

Graham

[[email protected]]

Bob H. wrote:
Full range speakers are a joke !

Oh, but they're a wonderful-sounding joke, and make me give me a sense
of satisfaction and relaxation while listening to music. Goosebumps
are regularly present.
Isn't that where we want to be in the end of it all?


YIKES & yikes.

A couple of preliminary statements so as to establish my position
clearly:

a) I have no difficulty with other individual's tastes and preferences,
as long as they do not attempt to dictate mine.

b) I believe that Full Range, Single Driver, conventional horn (e.g.
Lowther) speakers are a joke. So, I do not own any.

c) I also believe that under very specific conditions and with very
specific sources, FR/SD/CH speakers can sound ethereally beautiful. I
have heard such, so this is an opinion based on experience. But I still
do not own any, nor would I expend funds to own any... at any price.

The difficulties I have experienced with the above is that when they
are required to produce substantial volume using orchestral sources
with very wide dynamic and peak-to-average ranges, they fail. Sometimes
miserably, some times just awfully, but they fail. And this is
irrespective of the amp(s) that may be driving them.

There is a part of this hobby that attempts to do more-with-less, the
goal is to get the maximum performance out of the least amount of
power. To that end, FR speakers are a useful tool. If one chooses (or
simply prefers) sources amenable to this sort of reproduction, this
solution can be quite elegant. But limited. My opinion.

There is a part of this hobby (to which I subscribe, primarily) that
takes more of a brute-force approach, expecting to get as close to the
Original Source Reproduction as is possible given the tools available.
I am quite realistic in that I understand that tube equipment is a
series of compromises from the git-go (as is SS, but slightly less so),
the goal being to get as close as possible. As well, *I* choose not to
limit my source material to the system, but attempt to go the other
way.

So: I own numerous pairs of multiple-driver, (relatively) inefficient
speakers, the most efficient of which is rated at 86db/M. All my
(three, soon four) tube amps are PP, and based from EL-84 through KT-88
outputs. My SS amps range from 40wpc/rms/8 to 200wpc/rms/8. Each has
its place in the choir, but I do not have the same expectations from
the 17 watt amp as from the 200 watt amp. Nor do I match them to the
same speakers in the same sized rooms and so forth. Some are sub/sat
systems, some are set up with a "Hafler Circuit" poor-man's surround
system, all are pretty damned nice in my opinion, which with the
addition of my wife's is the only one that counts in my home. Others
are entitled to the same privileges in their homes.

There are enough idiots, dangerous advisors and incompetent
pseudo-enginneers in this group without getting into a ****ing-contest
over one's choice of poison. Writing for myself, I cannot imagine
drinking Night Train Express, but millions of gallons are drunk every
year. And at the very same time, "designer Vodkas" (unflavored) I take
as a serious joke much as little speaker cable towers... but again,
millions of gallons are sold. De gustibus non est disputandum, just not
my money, thank you.

If we recognize that there are different approaches and different
tastes and solutions based on those tastes, we might be able to discuss
more of the hobby than those choices and the various idiocies attached
thereto. Opinions asked should be rendered, of course. But without the
invective unless dealing with invincible ignorance or malicious intent
as appears to be more and more common recently. And any creature or
exudation that attempts to dictate a singular taste or result is fair
game.

Peter Wieck
Wyncote, PA

[John Larkin]

On 24 Jul 2006 10:41:54 -0400, (Scott Dorsey) wrote:

John Larkin wrote:
On Sun, 23 Jul 2006 04:59:19 GMT, Prune
wrote:

I've tried cermet potentiometers for volume control, and in a blind test
(non-double, used dual switch with my friend) I can't tell the difference
between it and a stepped attenuator; however, in 7/10 trials me and 8/10
trials him heard difference between plastic pot and the cermet, both
preferring the cermet.

Please don't top post.

Agreed. But the problem with cermets is they are noisy as hell when
you turn them. That's fine for trimmers, but no so good for a volume
control on the front panel.

What's the origin of the noise? If the wiper drives a high impedance,
unstable wiper contact resistance will generate no noise.

John

[Phil Hobbs]

John Larkin wrote:
On Sun, 23 Jul 2006 17:44:28 +0000 (UTC),
(Ken Smith) wrote:


In article ,
Phat Bytestard wrote:
[....]

Anything above absolute zero not only emits IR energy, but
electrical noise as well. (speaking of electrical mediums, of course)

The truth is that they emit wide band electromagnetic noise. The spectrum
goes from DC to daylight. The bit that happens to be conducted out on the
leads we call electrical noise. There is IR and microwave and radio noise
there too.


The Johnson noise spectrum doesn't quite make it to daylight, but
peters out in the thz region. It couldn't be true white noise, because
then the power would be infinite.

John



Classical equipartition says that the mean energy per degree of freedom
is kT/2. There are simple ways to show that this is flat with
frequency, classically speaking. This breaks down where the Planck
rolloff sets in, at a frequency of order kT/h. The proportionality
constant k/h is about 20 GHz/K, so at room temperature it rolls off
somewhere around 6 THz. [There's actually another factor of about 1.26
since the Planck function is (hf/kT)/(exp(hf/kT)-1) instead of the usual
one-pole rolloff we're used to in circuits, so the 3 dB frequency is
actually closer to 8 THz at room temperature.)

The optical emission isn't flat with frequency, but has a peak frequency
proportional to temperature, and a FWHM of about two octaves. The
reason for this is that there are a lot more degrees of freedom as you
go to higher frequency--each 1-Hz slice corresponds to an annular sphere
in k-space, whose volume goes as f**2. Optical spectra are commonly
quoted in per-wavelength units, and converting from differential
frequency to differential wavelength gets you another factor of f**2, so
in per-wavelength terms the number of degrees of freedom goes as lambda**-4.

Cheers,

Phil Hobbs

[Stuart Welwood]

"Bob Quintal" wrote in message
...
John Larkin wrote
in :
On 22 Jul 2006 18:03:38 GMT, Bob Quintal

wrote:
I *do* work at 120 dB s/n ratios over DC-50 KHz bandwidths
and
I do use surface-mount thickfilm resistors.

Pretty much the same here,


Cool. I do NMR gradient-coil drivers. What do you do?

John

amongst other things, image sensor front ends for telescopes.

It just so happens that I am about to get involved in a project that
includes the design of low noise sensor electronics in a rather small space.
Having never worked with surface mount components before, what would you
gents suggest for prototyping equipment? Would the use of flex circuit
boards make any difference in your choice?

Many thanks in advance,

Stuart Welwood

[[email protected]]

Hi RATs!

Since no single driver can do everything, apparently they can do
nothing.

Big G's small mind is so coy.

Gee, big G, do you then propose that all full range speaker systems,
with as many drivers as you like, sound the same, just like all passive
devices, save the odd sicko resistor?

It is going to be fun for you when you grow up.

Happy Ears!
Al


Eeyore wrote:

There is no single driver that can properly recreate 20Hz to 20kHz. It's easy to see
why 2 and 3 way systems are the norm.

Graham

[John Larkin]

On 23 Jul 2006 20:10:35 -0700, wrote:


Shot noise and Johnson noise are both "white" which is to say,
frequency independent.

What kind of noise profile lets you separate the two?

The Johnson noise voltage is there with no bias, and the shot noise
depends on the current through the part.

John

[Eeyore]

" wrote:

Hi RATs!

Since no single driver can do everything, apparently they can do
nothing.

Big G's small mind is so coy.

Gee, big G, do you then propose that all full range speaker systems,
with as many drivers as you like, sound the same, just like all passive
devices, save the odd sicko resistor?

What on earth are you rabbiting on about ?


It is going to be fun for you when you grow up.

You're pathetic. A tribute to audiophoolery.

Graham

[Bob Quintal]

"Stuart Welwood" wrote in
:

"Bob Quintal" wrote in message
...
John Larkin
wrote in :
On 22 Jul 2006 18:03:38 GMT, Bob Quintal

wrote:
I *do* work at 120 dB s/n ratios over DC-50 KHz bandwidths
and
I do use surface-mount thickfilm resistors.

Pretty much the same here,


Cool. I do NMR gradient-coil drivers. What do you do?

John

amongst other things, image sensor front ends for telescopes.

It just so happens that I am about to get involved in a
project that includes the design of low noise sensor
electronics in a rather small space. Having never worked with
surface mount components before, what would you gents suggest
for prototyping equipment? Would the use of flex circuit
boards make any difference in your choice?

Many thanks in advance,

Stuart Welwood

We've seen good results using boards with rigid sections coupled
with flex sections. You might also want to investigate Sealed
Chip On Board techniques. I can't say more, but here is one
university paper that deals with the subject:.
http://www.css.taylor.edu/
~physics/minielec/publications/paper.html




--
Bob Quintal

PA is y I've altered my email address.

--
Posted via a free Usenet account from http://www.teranews.com

[[email protected]]

John Larkin wrote:
On 23 Jul 2006 20:10:35 -0700, wrote:


Shot noise and Johnson noise are both "white" which is to say,
frequency independent.

What kind of noise profile lets you separate the two?

The Johnson noise voltage is there with no bias, and the shot noise
depends on the current through the part.

Perfectly correct, but that would be a current dependence profile,
which doesn't seem to be quite what was being described.

--
Bill Sloman, Nijmegen

[John Larkin]

On 24 Jul 2006 15:46:38 -0700, wrote:


John Larkin wrote:
On 23 Jul 2006 20:10:35 -0700, wrote:


Shot noise and Johnson noise are both "white" which is to say,
frequency independent.

What kind of noise profile lets you separate the two?

The Johnson noise voltage is there with no bias, and the shot noise
depends on the current through the part.

Perfectly correct, but that would be a current dependence profile,
which doesn't seem to be quite what was being described.

Bob didn't specify that it was a frequency profile, you did. All he
said was "profile." I think his correct point is that one can use
simple techniques to separate them. Additional argument is just being
a pain in the ass.

John

[Mark]

You will note that carbon comps are
available in SURFACE MOUNT packaging, so *somebody*
with major engineering chops sees reasons to keep using
them.

I think carbon comps are better in handling pulsed power, like in radar
or flash tube circuits etc.

Mark

[Phat Bytestard]

On Mon, 24 Jul 2006 10:09:16 GMT, spud Gave us:

On 23 Jul 2006 11:03:26 GMT, Bob Quintal
wrote:

Prune wrote in
. 144.76:

John Larkin
wrote in :
http://www.eng.yale.edu/qlab/papers/..._shotnoise.pdf

They call it "current noise" right in the abstract, as the
Vishay people do.

They can call it George. The mechanism by which the noise is
generated is that of shot noise. irregardless of the name.

Please take this in the spirit of childish pedantry it's intended but
it makes me cringe when presumably educated people use the "word"
irregardless. A simple, "regardless" will do. Thank you, s.


INCONCEIVABLE! ;-]

[Phat Bytestard]

On 24 Jul 2006 10:41:54 -0400, (Scott Dorsey) Gave
us:

John Larkin wrote:
On Sun, 23 Jul 2006 04:59:19 GMT, Prune
wrote:

I've tried cermet potentiometers for volume control, and in a blind test
(non-double, used dual switch with my friend) I can't tell the difference
between it and a stepped attenuator; however, in 7/10 trials me and 8/10
trials him heard difference between plastic pot and the cermet, both
preferring the cermet.

Please don't top post.

Agreed. But the problem with cermets is they are noisy as hell when
you turn them. That's fine for trimmers, but no so good for a volume
control on the front panel.

ELECTRONIC variable resistor.

[Phat Bytestard]

On Mon, 24 Jul 2006 08:24:37 -0700, John Larkin
Gave us:

On 24 Jul 2006 10:41:54 -0400, (Scott Dorsey) wrote:

John Larkin wrote:
On Sun, 23 Jul 2006 04:59:19 GMT, Prune
wrote:

I've tried cermet potentiometers for volume control, and in a blind test
(non-double, used dual switch with my friend) I can't tell the difference
between it and a stepped attenuator; however, in 7/10 trials me and 8/10
trials him heard difference between plastic pot and the cermet, both
preferring the cermet.

Please don't top post.

Agreed. But the problem with cermets is they are noisy as hell when
you turn them. That's fine for trimmers, but no so good for a volume
control on the front panel.

What's the origin of the noise? If the wiper drives a high impedance,
unstable wiper contact resistance will generate no noise.


The surface quality of a first surface mirror is very flat, and very
fine grained in the macroscopic view.

The "drag surface" of a variable resistor has to be a couple hundred
times rougher than that. That is going to produce "noise" when
turned, and even when stopped as the contact surface upon the wiper
can and likely will always be different tiny points on the wiper
surface. It is rougher even than basic grain oriented polished
stainless at a certain finish. (maybe a number 4). Pretty rough is
the macro surface quality/texture realm.

[Phat Bytestard]

On Mon, 24 Jul 2006 11:33:03 -0600, "Stuart Welwood"
Gave us:

"Bob Quintal" wrote in message
...
John Larkin wrote
in :
On 22 Jul 2006 18:03:38 GMT, Bob Quintal

wrote:
I *do* work at 120 dB s/n ratios over DC-50 KHz bandwidths
and
I do use surface-mount thickfilm resistors.

Pretty much the same here,


Cool. I do NMR gradient-coil drivers. What do you do?

John

amongst other things, image sensor front ends for telescopes.

It just so happens that I am about to get involved in a project that
includes the design of low noise sensor electronics in a rather small space.
Having never worked with surface mount components before, what would you
gents suggest for prototyping equipment? Would the use of flex circuit
boards make any difference in your choice?

Many thanks in advance,

Stuart Welwood

Flex is expensive. Especially in short run numbers.

[John Larkin]

On Tue, 25 Jul 2006 02:28:06 GMT, Phat Bytestard
wrote:

On Mon, 24 Jul 2006 08:24:37 -0700, John Larkin
Gave us:

On 24 Jul 2006 10:41:54 -0400, (Scott Dorsey) wrote:

John Larkin wrote:
On Sun, 23 Jul 2006 04:59:19 GMT, Prune
wrote:

I've tried cermet potentiometers for volume control, and in a blind test
(non-double, used dual switch with my friend) I can't tell the difference
between it and a stepped attenuator; however, in 7/10 trials me and 8/10
trials him heard difference between plastic pot and the cermet, both
preferring the cermet.

Please don't top post.

Agreed. But the problem with cermets is they are noisy as hell when
you turn them. That's fine for trimmers, but no so good for a volume
control on the front panel.

What's the origin of the noise? If the wiper drives a high impedance,
unstable wiper contact resistance will generate no noise.


The surface quality of a first surface mirror is very flat, and very
fine grained in the macroscopic view.

The "drag surface" of a variable resistor has to be a couple hundred
times rougher than that. That is going to produce "noise" when
turned, and even when stopped as the contact surface upon the wiper
can and likely will always be different tiny points on the wiper
surface. It is rougher even than basic grain oriented polished
stainless at a certain finish. (maybe a number 4). Pretty rough is
the macro surface quality/texture realm.

But how does that create electrical noise?

John

[Ken Smith]

In article ,
John Larkin wrote:
On Sun, 23 Jul 2006 17:44:28 +0000 (UTC),
(Ken Smith) wrote:

In article ,
Phat Bytestard wrote:
[....]
Anything above absolute zero not only emits IR energy, but
electrical noise as well. (speaking of electrical mediums, of course)

The truth is that they emit wide band electromagnetic noise. The spectrum
goes from DC to daylight. The bit that happens to be conducted out on the
leads we call electrical noise. There is IR and microwave and radio noise
there too.

The Johnson noise spectrum doesn't quite make it to daylight, but
peters out in the thz region. It couldn't be true white noise, because
then the power would be infinite.

People have told me a million times not to exaggerate but sometimes I
still do. At some point, like the THz range as you suggest, the energy in
a photon starts to become too much to be ignored.




--
--
forging knowledge

[Phat Bytestard]

On Mon, 24 Jul 2006 20:07:24 -0700, John Larkin
Gave us:

On Tue, 25 Jul 2006 02:28:06 GMT, Phat Bytestard
wrote:

On Mon, 24 Jul 2006 08:24:37 -0700, John Larkin
Gave us:

On 24 Jul 2006 10:41:54 -0400, (Scott Dorsey) wrote:

John Larkin wrote:
On Sun, 23 Jul 2006 04:59:19 GMT, Prune
wrote:

I've tried cermet potentiometers for volume control, and in a blind test
(non-double, used dual switch with my friend) I can't tell the difference
between it and a stepped attenuator; however, in 7/10 trials me and 8/10
trials him heard difference between plastic pot and the cermet, both
preferring the cermet.

Please don't top post.

Agreed. But the problem with cermets is they are noisy as hell when
you turn them. That's fine for trimmers, but no so good for a volume
control on the front panel.

What's the origin of the noise? If the wiper drives a high impedance,
unstable wiper contact resistance will generate no noise.


The surface quality of a first surface mirror is very flat, and very
fine grained in the macroscopic view.

The "drag surface" of a variable resistor has to be a couple hundred
times rougher than that. That is going to produce "noise" when
turned, and even when stopped as the contact surface upon the wiper
can and likely will always be different tiny points on the wiper
surface. It is rougher even than basic grain oriented polished
stainless at a certain finish. (maybe a number 4). Pretty rough is
the macro surface quality/texture realm.

But how does that create electrical noise?

John

While the wiper is still or moving?

While moving, it should be obvious. The locations where conduction
is taking place are moving all over the wiper surface, and there are
even microscopic arcs taking place If the two mediums were bound
together covalently, I'd say no noise, but since oxides and oxygen and
dissimilar mediums are concerned (wiper metal over some form of carbon
slurry or deposition) I'd say there is room to argue that some noise
might occur through those pathways.

Wiper still... Interfaces between mediums and oxides, less noise.

Tastes great, less filling.

[John Larkin]

On Tue, 25 Jul 2006 05:09:29 GMT, Phat Bytestard
wrote:

On Mon, 24 Jul 2006 20:07:24 -0700, John Larkin
Gave us:

On Tue, 25 Jul 2006 02:28:06 GMT, Phat Bytestard
wrote:

On Mon, 24 Jul 2006 08:24:37 -0700, John Larkin
Gave us:

On 24 Jul 2006 10:41:54 -0400, (Scott Dorsey) wrote:

John Larkin wrote:
On Sun, 23 Jul 2006 04:59:19 GMT, Prune
wrote:

I've tried cermet potentiometers for volume control, and in a blind test
(non-double, used dual switch with my friend) I can't tell the difference
between it and a stepped attenuator; however, in 7/10 trials me and 8/10
trials him heard difference between plastic pot and the cermet, both
preferring the cermet.

Please don't top post.

Agreed. But the problem with cermets is they are noisy as hell when
you turn them. That's fine for trimmers, but no so good for a volume
control on the front panel.

What's the origin of the noise? If the wiper drives a high impedance,
unstable wiper contact resistance will generate no noise.


The surface quality of a first surface mirror is very flat, and very
fine grained in the macroscopic view.

The "drag surface" of a variable resistor has to be a couple hundred
times rougher than that. That is going to produce "noise" when
turned, and even when stopped as the contact surface upon the wiper
can and likely will always be different tiny points on the wiper
surface. It is rougher even than basic grain oriented polished
stainless at a certain finish. (maybe a number 4). Pretty rough is
the macro surface quality/texture realm.

But how does that create electrical noise?

John

While the wiper is still or moving?

While moving, it should be obvious.

Not to me. Noise requires potentials, and resistors don't do that.

The locations where conduction
is taking place are moving all over the wiper surface, and there are
even microscopic arcs taking place

Arcs? At audio signal levels?

John

[Eeyore]

John Larkin wrote:

On Tue, 25 Jul 2006 05:09:29 GMT, Phat Bytestard
wrote:

On Mon, 24 Jul 2006 20:07:24 -0700, John Larkin
Gave us:

On Tue, 25 Jul 2006 02:28:06 GMT, Phat Bytestard
wrote:

On Mon, 24 Jul 2006 08:24:37 -0700, John Larkin
Gave us:

On 24 Jul 2006 10:41:54 -0400, (Scott Dorsey) wrote:

John Larkin wrote:
On Sun, 23 Jul 2006 04:59:19 GMT, Prune
wrote:

I've tried cermet potentiometers for volume control, and in a blind test
(non-double, used dual switch with my friend) I can't tell the difference
between it and a stepped attenuator; however, in 7/10 trials me and 8/10
trials him heard difference between plastic pot and the cermet, both
preferring the cermet.

Please don't top post.

Agreed. But the problem with cermets is they are noisy as hell when
you turn them. That's fine for trimmers, but no so good for a volume
control on the front panel.

What's the origin of the noise? If the wiper drives a high impedance,
unstable wiper contact resistance will generate no noise.


The surface quality of a first surface mirror is very flat, and very
fine grained in the macroscopic view.

The "drag surface" of a variable resistor has to be a couple hundred
times rougher than that. That is going to produce "noise" when
turned, and even when stopped as the contact surface upon the wiper
can and likely will always be different tiny points on the wiper
surface. It is rougher even than basic grain oriented polished
stainless at a certain finish. (maybe a number 4). Pretty rough is
the macro surface quality/texture realm.

But how does that create electrical noise?

John

While the wiper is still or moving?

While moving, it should be obvious.

Not to me. Noise requires potentials, and resistors don't do that.

But as connections are varying, Vout / Vin also varies. This creates the noise.
Think of the condition with a DC input and it's more immediately obvious.

Graham

[Phat Bytestard]

On Mon, 24 Jul 2006 22:51:37 -0700, John Larkin
Gave us:

On Tue, 25 Jul 2006 05:09:29 GMT, Phat Bytestard
wrote:

On Mon, 24 Jul 2006 20:07:24 -0700, John Larkin
Gave us:

On Tue, 25 Jul 2006 02:28:06 GMT, Phat Bytestard
wrote:

On Mon, 24 Jul 2006 08:24:37 -0700, John Larkin
Gave us:

On 24 Jul 2006 10:41:54 -0400, (Scott Dorsey) wrote:

John Larkin wrote:
On Sun, 23 Jul 2006 04:59:19 GMT, Prune
wrote:

I've tried cermet potentiometers for volume control, and in a blind test
(non-double, used dual switch with my friend) I can't tell the difference
between it and a stepped attenuator; however, in 7/10 trials me and 8/10
trials him heard difference between plastic pot and the cermet, both
preferring the cermet.

Please don't top post.

Agreed. But the problem with cermets is they are noisy as hell when
you turn them. That's fine for trimmers, but no so good for a volume
control on the front panel.

What's the origin of the noise? If the wiper drives a high impedance,
unstable wiper contact resistance will generate no noise.


The surface quality of a first surface mirror is very flat, and very
fine grained in the macroscopic view.

The "drag surface" of a variable resistor has to be a couple hundred
times rougher than that. That is going to produce "noise" when
turned, and even when stopped as the contact surface upon the wiper
can and likely will always be different tiny points on the wiper
surface. It is rougher even than basic grain oriented polished
stainless at a certain finish. (maybe a number 4). Pretty rough is
the macro surface quality/texture realm.

But how does that create electrical noise?

John

While the wiper is still or moving?

While moving, it should be obvious.

Not to me. Noise requires potentials, and resistors don't do that.

The locations where conduction
is taking place are moving all over the wiper surface, and there are
even microscopic arcs taking place

Arcs? At audio signal levels?

You are not thinking in the microscopic level.

Instead of volts per mil, it would be like millivolts per micron.
If oxides keep a "wiper" from making "intimate" contact, there will be
tiny little breach events that take place as electron bore through the
oxides and the wiper scrapes through. Generally though it would simply
be shot noise magnified by passage through a smaller surface area of
contact. And end cap has more total surface area of contact than does
a pair or a few wiper noses. Sniff, sniff... Hey... that's it!
Sniffing Noise!

[Bob Quintal]

Phat Bytestard wrote in
:

On Mon, 24 Jul 2006 22:51:37 -0700, John Larkin
Gave us:

On Tue, 25 Jul 2006 05:09:29 GMT, Phat Bytestard
wrote:

On Mon, 24 Jul 2006 20:07:24 -0700, John Larkin
Gave us:

On Tue, 25 Jul 2006 02:28:06 GMT, Phat Bytestard
wrote:

On Mon, 24 Jul 2006 08:24:37 -0700, John Larkin
Gave us:

On 24 Jul 2006 10:41:54 -0400, (Scott
Dorsey) wrote:

John Larkin
wrote:
On Sun, 23 Jul 2006 04:59:19 GMT, Prune
wrote:

I've tried cermet potentiometers for volume control,
and in a blind test (non-double, used dual switch with
my friend) I can't tell the difference between it and a
stepped attenuator; however, in 7/10 trials me and 8/10
trials him heard difference between plastic pot and the
cermet, both preferring the cermet.

Please don't top post.

Agreed. But the problem with cermets is they are noisy
as hell when you turn them. That's fine for trimmers,
but no so good for a volume control on the front panel.

What's the origin of the noise? If the wiper drives a high
impedance, unstable wiper contact resistance will generate
no noise.


The surface quality of a first surface mirror is very
flat, and very
fine grained in the macroscopic view.

The "drag surface" of a variable resistor has to be a
couple hundred
times rougher than that. That is going to produce "noise"
when turned, and even when stopped as the contact surface
upon the wiper can and likely will always be different tiny
points on the wiper surface. It is rougher even than basic
grain oriented polished stainless at a certain finish.
(maybe a number 4). Pretty rough is the macro surface
quality/texture realm.

But how does that create electrical noise?

John

While the wiper is still or moving?

While moving, it should be obvious.

Not to me. Noise requires potentials, and resistors don't do
that.

The locations where conduction
is taking place are moving all over the wiper surface, and
there are even microscopic arcs taking place

Arcs? At audio signal levels?

You are not thinking in the microscopic level.

Instead of volts per mil, it would be like millivolts per
micron.
If oxides keep a "wiper" from making "intimate" contact, there
will be tiny little breach events that take place as electron
bore through the oxides and the wiper scrapes through.
Generally though it would simply be shot noise magnified by
passage through a smaller surface area of contact. And end
cap has more total surface area of contact than does a pair or
a few wiper noses. Sniff, sniff... Hey... that's it!
Sniffing Noise!

What somebody obviously forgot is that microscopic doesn't apply
to the wiper contact surface area. Each of the locations where
"conduction is taking place" is in parallel with thousands of
other locations where "conduction is taking place". This aso
prevents arcing because of the shunt resistance of the other
contact points.

--
Bob Quintal

PA is y I've altered my email address.

--
Posted via a free Usenet account from http://www.teranews.com

[Bob Quintal]

(Scott Dorsey) wrote in
:

John Larkin
wrote:
wrote:

The "drag surface" of a variable resistor has to be a
couple hundred
times rougher than that. That is going to produce "noise"
when turned, and even when stopped as the contact surface
upon the wiper can and likely will always be different tiny
points on the wiper surface. It is rougher even than basic
grain oriented polished stainless at a certain finish. (maybe
a number 4). Pretty rough is the macro surface
quality/texture realm.

But how does that create electrical noise?

When you turn the pot, it bounces up and down across the
surface. There is mechanical noise, and a corresponding
change in resistance that causes electrical noise.

When you stop turning the pot, the noise goes away. As a
result, these are great for trimmer pots and things that get
occasionally adjusted, but unacceptable for controls you'll be
riding all day long like channel gains. --scott


So its an issue of the wiper arm lacking the proper tension to
keep it from bouncing?

--
Bob Quintal

PA is y I've altered my email address.

--
Posted via a free Usenet account from http://www.teranews.com

[John Larkin]

On Tue, 25 Jul 2006 07:09:55 +0100, Eeyore
wrote:



John Larkin wrote:

On Tue, 25 Jul 2006 05:09:29 GMT, Phat Bytestard
wrote:

On Mon, 24 Jul 2006 20:07:24 -0700, John Larkin
Gave us:

On Tue, 25 Jul 2006 02:28:06 GMT, Phat Bytestard
wrote:

On Mon, 24 Jul 2006 08:24:37 -0700, John Larkin
Gave us:

On 24 Jul 2006 10:41:54 -0400, (Scott Dorsey) wrote:

John Larkin wrote:
On Sun, 23 Jul 2006 04:59:19 GMT, Prune
wrote:

I've tried cermet potentiometers for volume control, and in a blind test
(non-double, used dual switch with my friend) I can't tell the difference
between it and a stepped attenuator; however, in 7/10 trials me and 8/10
trials him heard difference between plastic pot and the cermet, both
preferring the cermet.

Please don't top post.

Agreed. But the problem with cermets is they are noisy as hell when
you turn them. That's fine for trimmers, but no so good for a volume
control on the front panel.

What's the origin of the noise? If the wiper drives a high impedance,
unstable wiper contact resistance will generate no noise.


The surface quality of a first surface mirror is very flat, and very
fine grained in the macroscopic view.

The "drag surface" of a variable resistor has to be a couple hundred
times rougher than that. That is going to produce "noise" when
turned, and even when stopped as the contact surface upon the wiper
can and likely will always be different tiny points on the wiper
surface. It is rougher even than basic grain oriented polished
stainless at a certain finish. (maybe a number 4). Pretty rough is
the macro surface quality/texture realm.

But how does that create electrical noise?

John

While the wiper is still or moving?

While moving, it should be obvious.

Not to me. Noise requires potentials, and resistors don't do that.

But as connections are varying, Vout / Vin also varies. This creates the noise.
Think of the condition with a DC input and it's more immediately obvious.

Graham

That will just result in a tiny amplitude modulation of whatever sound
level is there at that instant, and the sound level is changing all
the time anyway, especially so as you're turning the pot on purpose
already. That won't be very, whether the pot is cermet, plastic, or
wirewound.

The difference with DC is that you can't hear DC, but you can hear the
small variations in DC - real noise - that a bad pot can create.

OK, new audiophool product: volume controls based on variable
capacitance.

John

[Phil Hobbs]

rick H wrote:
In sci.electronics.design Phil Hobbs wrote:

John Larkin wrote:

The Johnson noise spectrum doesn't quite make it to daylight, but
peters out in the thz region. It couldn't be true white noise, because
then the power would be infinite.


Classical equipartition says that the mean energy per degree of freedom
is kT/2. There are simple ways to show that this is flat with
frequency, classically speaking. This breaks down where the Planck
rolloff sets in, at a frequency of order kT/h. The proportionality
constant k/h is about 20 GHz/K, so at room temperature it rolls off
somewhere around 6 THz. [There's actually another factor of about 1.26
since the Planck function is (hf/kT)/(exp(hf/kT)-1) instead of the usual
one-pole rolloff we're used to in circuits, so the 3 dB frequency is
actually closer to 8 THz at room temperature.)



Something doesn't stack up there, Phil. It's common to replace the
exponential term with the series expansion 1 + hf/kT, which is a good
approximation down to a few Kelvin (I assume this is the method you
talked about which gives the classical result.)

The series expansion gives you (with your formula)
(hf/kT)/(exp(hf/kT)-1) ~= (hf/kT)/(1 + hf/kT -1)
= (hf/kT)/(hf/KT)
= 1
which is an interesting (dimensionless) result!

Right, I'm quoting the Planck *rolloff*. It's normalized to 1 at low
frequency.

Cheers,

Phil Hobbs

[Phil Hobbs]

Ken Smith wrote:
In article ,
John Larkin wrote:

The Johnson noise spectrum doesn't quite make it to daylight, but
peters out in the thz region. It couldn't be true white noise, because
then the power would be infinite.


People have told me a million times not to exaggerate but sometimes I
still do. At some point, like the THz range as you suggest, the energy in
a photon starts to become too much to be ignored.

Sometimes that rolloff matters, even in circuits. I'm building
electrical detectors (not photodiodes or photoresistors) that detect 200
THz signals by rectification. (Current efficiency level is about 4%,
but they've only been working for a month or so, and the next best
reported number is about 0.1%.)

Cheers,

Phil Hobbs

[John Larkin]

On 25 Jul 2006 09:45:40 -0400, (Scott Dorsey) wrote:

John Larkin wrote:
wrote:

The "drag surface" of a variable resistor has to be a couple hundred
times rougher than that. That is going to produce "noise" when
turned, and even when stopped as the contact surface upon the wiper
can and likely will always be different tiny points on the wiper
surface. It is rougher even than basic grain oriented polished
stainless at a certain finish. (maybe a number 4). Pretty rough is
the macro surface quality/texture realm.

But how does that create electrical noise?

When you turn the pot, it bounces up and down across the surface. There
is mechanical noise, and a corresponding change in resistance that causes
electrical noise.

Please explain how a change in resistance creates voltage.

John

[[email protected]]

John Larkin wrote:
On 24 Jul 2006 15:46:38 -0700, wrote:


John Larkin wrote:
On 23 Jul 2006 20:10:35 -0700, wrote:


Shot noise and Johnson noise are both "white" which is to say,
frequency independent.

What kind of noise profile lets you separate the two?

The Johnson noise voltage is there with no bias, and the shot noise
depends on the current through the part.

Perfectly correct, but that would be a current dependence profile,
which doesn't seem to be quite what was being described.

Bob didn't specify that it was a frequency profile, you did. All he
said was "profile." I think his correct point is that one can use
simple techniques to separate them. Additional argument is just being
a pain in the ass.

Be that as it may, he didn't support his identification of the excess
noise as shot noise with any kind of meaningful argument - he just
talked about a "noise profile" which is just a tad unspecific.

--
Bill Sloman, Nijmegen

[Scott Dorsey]

John Larkin wrote:
On 25 Jul 2006 09:45:40 -0400, (Scott Dorsey) wrote:

When you turn the pot, it bounces up and down across the surface. There
is mechanical noise, and a corresponding change in resistance that causes
electrical noise.

Please explain how a change in resistance creates voltage.

It does not create voltage, it creates a change in the drop in voltage
from the signal that is already across the pot. If there is no signal
and no DC offset, there will be no noise either. But if there is no
signal and no DC, there is no need for a pot.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Sander deWaal]

Eeyore said:


You're pathetic. A tribute to audiophoolery.


Al 's a happy tinkerer.
With all respect for your status as a pro designer (so am I, in a
smaller and different way), I'm afraid you've lost that ability
somewhere along the way............

--
"All amps sound alike, but some sound more alike than others".

[Arny Krueger]

"Prune" wrote in message
4.76...

Couldn't it be that fine differences can only be heard in ultra high
resolution systems, where everything is optimized? Or that while some
individual part changes may be inaudible, a number of simultaneous
changes would sum to exceed a perception threshold?

Yup, the Emperor's new clothes can only be seen in the finest venues. ;-)

[Arny Krueger]

"Eeyore" wrote in
message ...


"Bob H." wrote:

Whoops, I meant 87 db/M
87dbM/m with 4 ohm nominal impedance and who-knows-what impedance dips.

and alnico.
(alinco), Hammer super 12's, and fostex

Good God !

You think that Alnico magnets somehow produce superior sound over other
magnets
? Is that lame or what ?

Yes, there are Alnico gauss and ceramic gauss. The former are more
effective. ;-)

[Arny Krueger]

"Bob H." wrote in message
ups.com...

Full range speakers are a joke !

Oh, but they're a wonderful-sounding joke, and make me give me a sense
of satisfaction and relaxation while listening to music.

Hmm, so you have a preference for rough, limited frequency response?

Goosebumps are regularly present.

I suggest that you raise the room temperature to 65 degrees F, or higher.