Driver to drive?

If you feed a very sharp edge into a badly designed feedback amplifier
there can be momentary distortion which might be audible.
However, in a well designed amplifer there will be a passive input
low-pass filter to smooth off such signals and prevent this effect.
The fashion for specifying bandwidths that are only audible to bats
can make things worse than tailoring audio equipment to what is
actually audible to humans.

Don't believe everything in "the literature".

John
Click to expand...
You need that passive filtering to keep RF out of the amplifier as well.
 
On Sun, 03 Feb 2013 18:55:42 -0600, John Fields
<jfields@austininstruments.com> wrote:


All true, but since it's only the rate of change of amplitude of the
pulse - which goes with the velocity of the target - which drives the
switch, there's no range information to be gleaned.

There are sensor arrays available with multiple transducers.

Knowing, then, the focal length of the lens, the distance between the
transducers and the difference in time between the responses of the
transducers, the range to the target can be calculated.
Click to expand...
---
Oops...

That's wrong.

A target with a high velocity far from the sensor could the elicit the
same response from the sensor as a nearer, slower target, so range
can't be resolved that way.

Sorry 'bout that.

--
JF
 
On Mon, Feb 04, 2013 at 10:41:36AM -0800, John Larkin wrote:
On Sun, 03 Feb 2013 21:00:44 -0500, Uncle Steve <stevet810@gmail.com
wrote:

More than a century has passed since science laid down sound
propositions as to the origins of the universe, but how many have
mastered them or possess the really scientific spirit of criticism? A
few thousands at the outside, who are lost in the midst of hundreds of
millions still steeped in prejudices and superstitions worthy of
savages, who are consequently ever ready to serve as puppets for
religious impostors. -- Peter Kropotkin

Cool. What is the origin of the universe?
Click to expand...
Evidently you don't understand the limitations of closed systems.
There may be no way of discovering how existence and the Universe came
about. I recommend you should not ask that question since the answer
is unknowable. If you want to believe in "God" that's fine, but you
will have to live with the fact the designation is nothing more than a
substitute for real knowledge.

If you mean 'origin' in a Cartesian sense, I can only say that your
suggestion of omniscience is misplaced.


Regards,

Uncle Steve

--
More than a century has passed since science laid down sound
propositions as to the origins of the universe, but how many have
mastered them or possess the really scientific spirit of criticism? A
few thousands at the outside, who are lost in the midst of hundreds of
millions still steeped in prejudices and superstitions worthy of
savages, who are consequently ever ready to serve as puppets for
religious impostors. -- Peter Kropotkin
 
On 5/02/2013 7:21 a.m., John Larkin wrote:
On Mon, 04 Feb 2013 12:22:40 +1300, Gib Bogle <g.bogle@auckland.ac.nz
wrote:

On 3/02/2013 4:28 a.m., John Larkin wrote:


Audio is such nonsense.



There is good comedy value in some of the hifi mags.

Years ago I read about a very conscientious speaker designer in the UK
who had the goal of making a good cheap speaker. He came up with a good
design, but couldn't sell them. Finally (on advice) he had to resort to
pushing the selling price up significantly, then they started selling.
He was quite discouraged by this experience, while for others, of
course, it represented a commercial opportunity.

In the first .com boom, local restaurants discovered that the more
they charged for a bottle of wine, the more they sold. Restaurants
like Boulevard had several wines in the $1000 to $3000 range.

Beer is the new wine, and The Monks Kettle usually has something in
the $80 range.
Click to expand...
Talk about pissing it away.
 
In article <4lp0h85ioe8gb9vacbb1jvcjbi7271ffut@4ax.com>,
Jeff Liebermann <jeffl@cruzio.com> wrote:

Too big to always have with you. They're probably not allowed in many
classes/tests, either.

Bummer. I guess times have changed. When I went to college (late
1960's), I built my own portable analog computer. There was some
resistance to my using it on exams, but the administration relented
when I mumbled something about the college appearing to be
anti-technology if the story leaked.
Click to expand...
Back when I took my amateur radio exams in 2002, I was allowed to
bring a calculator, but only if it was one which had no pre-programmed
formulas. Programmable calculators were allowed, if and only if all
of the memory was cleared before the exam started.

The only working electronic calculator I had around was a big HP
beast, programmable in a BASIC dialect. I couldn't even convince
*myself* that I knew how to completely clear its memory and rule out
the presence of any ROM formulas, so I left it at home.

Instead, I brought a Pickett slide rule :)

--
Dave Platt <dplatt@radagast.org> AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!
 
On Sat, 2 Feb 2013 19:10:37 -0800 (PST), "langwadt@fonz.dk"
<langwadt@fonz.dk> wrote:

On Feb 3, 4:00 am, Jamie
jamie_ka1lpa_not_valid_after_ka1l...@charter.net> wrote:
Jasen Betts wrote:
On 2013-02-01, Robert Macy <robert.a.m...@gmail.com> wrote:

First place I'd look...
Electronic ballasts require an EMI filter in front of them to prevent
the conducted emanations. What you have there is a capacitor across
the AC mains followed by some husky inductance. That makes the load
look incredibly inductive, not capacitive - with main impact as you
turn it off. To envision, simply unplug your PC very slowly from the
AC outlet. Even with it turned off, you'll draw an impressive arc. All
due to the stored energy in the EMI filter. I suspect it is THAT
energy that is welding the contacts together.

contacts can't weld closed while they are open.
therfore the damage is occurring when they close
capacitor derived surge current through the bouncing
contacts heats them up to melting and the weld closed.

  They most certainly can weld together while they are in
the process of opening with induction loads. Which is why
special designs are out there just for handling induction
loads.


I have hard time seeing how it can happen when opening, arc
start when they are already moving apart so unless you close them
instantly after being melted by the opening arc I don't see how
they could weld

at closing it is more like spot welding, melt and press together

   If you don't use the correct contact design for these types
of loads, the relay will not last long.

Jamie

sure arcing at opening will eat the contacts, but that is different


-Lasse
Click to expand...
There are multiple processes going on. Contacts that are badly pitted are
easier to weld on closure due to irregular contact area.

?-)
 
On Mon, 04 Feb 2013 16:01:57 -0800, Joerg <invalid@invalid.invalid> wrote:

Tim Wescott wrote:
Just got this from my kid:

"Also, a cool birthday present would be an RPN calculator with a
three-stack display, stack switch, and variable base log. Or even any
(non-graphing) calculator with variable base log function (realcalc is
nice, but only has log base 10 and log base e, and I don't like my
graphing calculator. Also I can't use realcalc for tests)."

Does anyone even _make_ RPN calculators any more?


Yup. Hewlett-Packard :)

http://www.walmart.com/ip/HP-35S-Scientific-Calculator/6015793
Click to expand...
The 35S is pretty terrible, a mockery of the wonderful HP35. I mostly use ebay
32SII's.


--

John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators
 
On Mon, 04 Feb 2013 19:37:08 -0500, krw@attt.bizz wrote:

On Mon, 04 Feb 2013 17:48:25 -0600, Tim Wescott <tim@seemywebsite.com
wrote:

Just got this from my kid:

"Also, a cool birthday present would be an RPN calculator with a
three-stack display, stack switch, and variable base log. Or even any
(non-graphing) calculator with variable base log function (realcalc is
nice, but only has log base 10 and log base e, and I don't like my
graphing calculator. Also I can't use realcalc for tests)."

Does anyone even _make_ RPN calculators any more?

Sure. HP, who else?

Or any variable base log non-graphing calculator?

And yes, I am going to tell him to suck it up and accept that

log_x y = (ln y)/(ln x)

is so easy that a variable-base log function is probably not in the cards.

That's the way the HP folks had it pegged forty years ago. Tell him to
program a function key if he's that lazy. ;-)
Click to expand...
The 32SII has log10 and ln.


--

John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators
 
On Sun, 03 Feb 2013 09:39:39 -0500, Uncle Steve <stevet810@gmail.com>
wrote:

On Sat, Feb 02, 2013 at 08:48:41PM -0500, Bob Engelhardt wrote:
On 2/2/2013 11:09 AM, Uncle Steve wrote:
When I've properly broken in my new drivers I'll make a youtube video
so you can hear the results for yourself....

No emoticon, so I assume that he's serious. In which case, even though
I know nothing about what he's talking about, I do know that he is full
of shit. Youtube ... gimme a break!!! Bob

It was a joke, but several people were bound to mistake it for a
serious proposition.

Perhaps I will make a youtube video and see what people say.


Regards,

Uncle Steve
Click to expand...
If only you would take your sig to heart.

?=/
 
On Mon, 04 Feb 2013 19:31:19 -0800, John Larkin
<jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

On Mon, 04 Feb 2013 19:37:08 -0500, krw@attt.bizz wrote:

On Mon, 04 Feb 2013 17:48:25 -0600, Tim Wescott <tim@seemywebsite.com
wrote:

Just got this from my kid:

"Also, a cool birthday present would be an RPN calculator with a
three-stack display, stack switch, and variable base log. Or even any
(non-graphing) calculator with variable base log function (realcalc is
nice, but only has log base 10 and log base e, and I don't like my
graphing calculator. Also I can't use realcalc for tests)."

Does anyone even _make_ RPN calculators any more?

Sure. HP, who else?

Or any variable base log non-graphing calculator?

And yes, I am going to tell him to suck it up and accept that

log_x y = (ln y)/(ln x)

is so easy that a variable-base log function is probably not in the cards.

That's the way the HP folks had it pegged forty years ago. Tell him to
program a function key if he's that lazy. ;-)

The 32SII has log10 and ln.
Click to expand...
So did the 45 but they don't have log(pi). ;-)
 
On Sun, 03 Feb 2013 10:43:06 -0500, Uncle Steve <stevet810@gmail.com>
wrote:

there have been speakers with dual coils where one was used for feed
back, afair it
had problems with varying coupling between the coils

The most interesting one and probably the one that works the best, was
a piezo disc
glued to the center dome measuring acceleration to do a full PID
regulator, reducing
distortion and setting the response

That's crazy. But the best way would probably be laser
interferometry with a tiny mirror glued to the driver. Not sure what
you'd use as a sensor.

I can see it now. Someone will jam a Raspberry PI in their speakers
and run the correcting factor back to the amp over Gigahertz Ethernet
Click to expand...
Bawg, i do detest the Gbit/s Ethernet being used way stupidly as a panacea
buzz word. Does nobody understand that Ethernet has uncontrolled latency?
Packets may arrive out of order? For snot sake if you want to ship
digitized audio (or video for that matter) data fast with controlled
latency and guaranteed in order reception use D1 or any of several SMPTE
Standard protocols.

[still boiling mad]

?-)
 
On Sun, 03 Feb 2013 10:43:06 -0500, Uncle Steve <stevet810@gmail.com>
wrote:

That's all for low frequency like subwoofers but that is also where
most of the problems
are

You seem to be saying that the voicecoil in low/mid drivers is the
primary target of negative feedback, but would it not also apply to
the high-frequency signal components? To what extent I could not
guess. I suppose it depends on the design, but people tend to forget
that the nominal 20kHz range of human hearing isn't the whole
enchilada, and there are several ultrasonic applications where signal
fidelity is fairly critical -- like those imaging devices they use to
examine a foetus to determine gender and general health of its
development.


Regards,

Uncle Steve
Click to expand...
Please don't mix (or mistake of conflate) apples and tarantulas.

?-)
 
On 5/02/2013 12:17 p.m., John Larkin wrote:
On Mon, 04 Feb 2013 15:14:38 -0500, Uncle Steve <stevet810@gmail.com
wrote:

On Mon, Feb 04, 2013 at 10:41:36AM -0800, John Larkin wrote:
On Sun, 03 Feb 2013 21:00:44 -0500, Uncle Steve <stevet810@gmail.com
wrote:

More than a century has passed since science laid down sound
propositions as to the origins of the universe, but how many have
mastered them or possess the really scientific spirit of criticism? A
few thousands at the outside, who are lost in the midst of hundreds of
millions still steeped in prejudices and superstitions worthy of
savages, who are consequently ever ready to serve as puppets for
religious impostors. -- Peter Kropotkin

Cool. What is the origin of the universe?

Evidently you don't understand the limitations of closed systems.
There may be no way of discovering how existence and the Universe came
about.

Well, so much for science.
Click to expand...
He doesn't get it
 
"Tim Wescott" wrote in message
news:mo6dnSkf66xU1Y3MnZ2dnUVZ_qSdnZ2d@giganews.com...
Just got this from my kid:
Does anyone even _make_ RPN calculators any more?
Click to expand...
Hi Tim,
The HP35s of course, but it is in my opinion far from the usual HP
calculator quality standard. In particular a couple of annoying bugs makes
life difficult (in particular the strange way of hiding the exponent on the
rightmost part of the display with large numbers, a good way to get
erroneous results except if you are clever enough to shoft left the
display...)
A far better choice : get your hands on one of the "HP15C limited edition"
series that HP sold last year. Very close to the original !
Friendly,
Robert
 
josephkk a écrit :
On Sun, 03 Feb 2013 10:43:06 -0500, Uncle Steve <stevet810@gmail.com
wrote:

there have been speakers with dual coils where one was used for feed
back, afair it
had problems with varying coupling between the coils

The most interesting one and probably the one that works the best, was
a piezo disc
glued to the center dome measuring acceleration to do a full PID
regulator, reducing
distortion and setting the response
That's crazy. But the best way would probably be laser
interferometry with a tiny mirror glued to the driver. Not sure what
you'd use as a sensor.

I can see it now. Someone will jam a Raspberry PI in their speakers
and run the correcting factor back to the amp over Gigahertz Ethernet


Bawg, i do detest the Gbit/s Ethernet being used way stupidly as a panacea
buzz word. Does nobody understand that Ethernet has uncontrolled latency?
Packets may arrive out of order? For snot sake if you want to ship
digitized audio (or video for that matter) data fast with controlled
latency and guaranteed in order reception use D1 or any of several SMPTE
Standard protocols.

[still boiling mad]

?-)
Click to expand...
Hey, that'll put some 'spread spectrum-ness' into the FB loop.
(another nice buzz word that'll magically save the world)
Or better, if you push to the limit, you'll get to 'fractal feed-back'
(tm), which obviously is the ultimate in 'distortion dithering' (tm) and
BSOAR (BullShit Optimized Audio Reproduction).

--
Thanks,
Fred.
 
John Larkin wrote:
On Mon, 04 Feb 2013 16:01:57 -0800, Joerg <invalid@invalid.invalid> wrote:

Tim Wescott wrote:
Just got this from my kid:

"Also, a cool birthday present would be an RPN calculator with a
three-stack display, stack switch, and variable base log. Or even any
(non-graphing) calculator with variable base log function (realcalc is
nice, but only has log base 10 and log base e, and I don't like my
graphing calculator. Also I can't use realcalc for tests)."

Does anyone even _make_ RPN calculators any more?

Yup. Hewlett-Packard :)

http://www.walmart.com/ip/HP-35S-Scientific-Calculator/6015793

The 35S is pretty terrible, a mockery of the wonderful HP35. I mostly use ebay
32SII's.
Click to expand...
Problem is, from the calculator of the good old times HP has only
revived the financial ones. So I am hoping my HP11C lasts another 30 year.

--
Regards, Joerg

http://www.analogconsultants.com/
 
On Tue, 05 Feb 2013 15:28:23 +0100, Fred Bartoli <" "> wrote:

[snip]
Hey, that'll put some 'spread spectrum-ness' into the FB loop.
(another nice buzz word that'll magically save the world)
Or better, if you push to the limit, you'll get to 'fractal feed-back'
(tm), which obviously is the ultimate in 'distortion dithering' (tm) and
BSOAR (BullShit Optimized Audio Reproduction).
Click to expand...
I like that, "BSOAR" >:-}

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.
 
Jim Thompson wrote:
On Tue, 05 Feb 2013 15:28:23 +0100, Fred Bartoli <" "> wrote:

[snip]

Hey, that'll put some 'spread spectrum-ness' into the FB loop.
(another nice buzz word that'll magically save the world)
Or better, if you push to the limit, you'll get to 'fractal feed-back'
(tm), which obviously is the ultimate in 'distortion dithering' (tm) and
BSOAR (BullShit Optimized Audio Reproduction).

I like that, "BSOAR" >:-}
Click to expand...

It'll never replace FUBAR
 
Jim Thompson a écrit :
On Tue, 05 Feb 2013 15:28:23 +0100, Fred Bartoli <" "> wrote:

[snip]
Hey, that'll put some 'spread spectrum-ness' into the FB loop.
(another nice buzz word that'll magically save the world)
Or better, if you push to the limit, you'll get to 'fractal feed-back'
(tm), which obviously is the ultimate in 'distortion dithering' (tm) and
BSOAR (BullShit Optimized Audio Reproduction).

I like that, "BSOAR" >:-}
Click to expand...
Yeah, that's the kind of bullshit that soars above the audio fields,
with two expectations:
- first, tickle some of your hot spots
- second break down any rationality


--
Thanks,
Fred.
 
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