I wonder if it would be possible to construct a speaker that "sees"
electric pulses as wave. IOW produce an acoustic sine-wave when hit
with a digital pulse of electricity. When "fed" the "steps" of PCM
pulses it should somehow "smoothen" or round the "points" of those
steps into waves.

In article ,
(Radium) wrote:

I wonder if it would be possible to construct a speaker that "sees"
electric pulses as wave. IOW produce an acoustic sine-wave when hit
with a digital pulse of electricity. When "fed" the "steps" of PCM
pulses it should somehow "smoothen" or round the "points" of those
steps into waves.

There are amps that feed normal speakers directly with digital pulses.
They're mostly for battery powered devices because small size and low
power consumption are their only advantages. Distortion isn't so great
at high frequencies and they radiate EMF.

At some point you have to end up with an analog force unless you want to
make a linear stepper motor. I can't imagine a linear stepper motor
sounding good.

In article ,
(Radium) wrote:

I wonder if it would be possible to construct a speaker that "sees"
electric pulses as wave. IOW produce an acoustic sine-wave when hit
with a digital pulse of electricity. When "fed" the "steps" of PCM
pulses it should somehow "smoothen" or round the "points" of those
steps into waves.

There are amps that feed normal speakers directly with digital pulses.
They're mostly for battery powered devices because small size and low
power consumption are their only advantages. Distortion isn't so great
at high frequencies and they radiate EMF.

At some point you have to end up with an analog force unless you want to
make a linear stepper motor. I can't imagine a linear stepper motor
sounding good.

"Kevin McMurtrie" wrote in message
...
In article ,
(Radium) wrote:

I wonder if it would be possible to construct a speaker that "sees"
electric pulses as wave. IOW produce an acoustic sine-wave when hit
with a digital pulse of electricity. When "fed" the "steps" of PCM
pulses it should somehow "smoothen" or round the "points" of those
steps into waves.

There are amps that feed normal speakers directly with digital pulses.
They're mostly for battery powered devices because small size and low
power consumption are their only advantages. Distortion isn't so great
at high frequencies and they radiate EMF.

At some point you have to end up with an analog force unless you want to
make a linear stepper motor. I can't imagine a linear stepper motor
sounding good.

There actually is a digital speaker. It consists of a flat membrane divided
into an array of squares, each of which can be in one of two states. A
computer algorithm is used to drive combinations of the squares to
approximate a continuum of sound levels.

I don't have the link. However, the sound was said to have an interesting
quality -- ie., not bad, but not compellingly good either.

"Kevin McMurtrie" wrote in message
...
In article ,
(Radium) wrote:

I wonder if it would be possible to construct a speaker that "sees"
electric pulses as wave. IOW produce an acoustic sine-wave when hit
with a digital pulse of electricity. When "fed" the "steps" of PCM
pulses it should somehow "smoothen" or round the "points" of those
steps into waves.

There are amps that feed normal speakers directly with digital pulses.
They're mostly for battery powered devices because small size and low
power consumption are their only advantages. Distortion isn't so great
at high frequencies and they radiate EMF.

At some point you have to end up with an analog force unless you want to
make a linear stepper motor. I can't imagine a linear stepper motor
sounding good.

There actually is a digital speaker. It consists of a flat membrane divided
into an array of squares, each of which can be in one of two states. A
computer algorithm is used to drive combinations of the squares to
approximate a continuum of sound levels.

I don't have the link. However, the sound was said to have an interesting
quality -- ie., not bad, but not compellingly good either.

"Radium" wrote in message
om

I wonder if it would be possible to construct a speaker that "sees"
electric pulses as wave.

In fact virtually all speakers do that right now.

IOW produce an acoustic sine-wave when hit
with a digital pulse of electricity.

In fact virtually all speakers do this right now.

When "fed" the "steps" of PCM
pulses it should somehow "smoothen" or round the "points" of those
steps into waves.

In fact virtually all speakers do this right now.

"Radium" wrote in message
om

I wonder if it would be possible to construct a speaker that "sees"
electric pulses as wave.

In fact virtually all speakers do that right now.

IOW produce an acoustic sine-wave when hit
with a digital pulse of electricity.

In fact virtually all speakers do this right now.

When "fed" the "steps" of PCM
pulses it should somehow "smoothen" or round the "points" of those
steps into waves.

In fact virtually all speakers do this right now.

"Robert Morein" wrote in message


There actually is a digital speaker. It consists of a flat membrane
divided
into an array of squares, each of which can be in one of two states. A
computer algorithm is used to drive combinations of the squares to
approximate a continuum of sound levels.

I don't have the link. However, the sound was said to have an interesting
quality -- ie., not bad, but not compellingly good either.


That would be one of those speakers reviewed in the many April editions of
audio mags over the last 20 years ?

geoff

"Robert Morein" wrote in message


There actually is a digital speaker. It consists of a flat membrane
divided
into an array of squares, each of which can be in one of two states. A
computer algorithm is used to drive combinations of the squares to
approximate a continuum of sound levels.

I don't have the link. However, the sound was said to have an interesting
quality -- ie., not bad, but not compellingly good either.


That would be one of those speakers reviewed in the many April editions of
audio mags over the last 20 years ?

geoff

"Arny Krueger" wrote in message
...
"Radium" wrote in message
om

I wonder if it would be possible to construct a speaker that "sees"
electric pulses as wave.

In fact virtually all speakers do that right now.

IOW produce an acoustic sine-wave when hit
with a digital pulse of electricity.

In fact virtually all speakers do this right now.

Not a pulse, but a continuous varying level.ie anaogue ac. Even class D
amps outputs are filtered to (hopefully) removed any digital info. Have you
any specific info regarding speakers being driven from anything other than
an analogue signal ?


geoff

"Arny Krueger" wrote in message
...
"Radium" wrote in message
om

I wonder if it would be possible to construct a speaker that "sees"
electric pulses as wave.

In fact virtually all speakers do that right now.

IOW produce an acoustic sine-wave when hit
with a digital pulse of electricity.

In fact virtually all speakers do this right now.

Not a pulse, but a continuous varying level.ie anaogue ac. Even class D
amps outputs are filtered to (hopefully) removed any digital info. Have you
any specific info regarding speakers being driven from anything other than
an analogue signal ?


geoff

"Geoff Wood" -nospam wrote in message

"Arny Krueger" wrote in message
...
"Radium" wrote in message
om

I wonder if it would be possible to construct a speaker that "sees"
electric pulses as wave.

In fact virtually all speakers do that right now.

IOW produce an acoustic sine-wave when hit
with a digital pulse of electricity.

In fact virtually all speakers do this right now.

Not a pulse, but a continuous varying level.i.e. anaogue ac. Even
class D amps outputs are filtered to (hopefully) removed any digital
info. Have you any specific info regarding speakers being driven
from anything other than an analogue signal ?

It's not hifi, but the speaker that is part of the original IBM PC spec has
always been driven with 5 volt pulses. In the Win31 and early win95 days
Microsoft provided a driver that created a PWM signal from MM audio, and
actually pushed voice-quality audio through it.

The filters on PWM amplifiers are there to deal with the thermal effects of
their high frequency hash, not necessarily its direct effects on sound
quality.

Conventional hifi loudspeaker systems typically have a high frequency pole
somewhere between 16 KHz and 30 KHz. It acts like an integrator at 44 KHz.

"Geoff Wood" -nospam wrote in message

"Arny Krueger" wrote in message
...
"Radium" wrote in message
om

I wonder if it would be possible to construct a speaker that "sees"
electric pulses as wave.

In fact virtually all speakers do that right now.

IOW produce an acoustic sine-wave when hit
with a digital pulse of electricity.

In fact virtually all speakers do this right now.

Not a pulse, but a continuous varying level.i.e. anaogue ac. Even
class D amps outputs are filtered to (hopefully) removed any digital
info. Have you any specific info regarding speakers being driven
from anything other than an analogue signal ?

It's not hifi, but the speaker that is part of the original IBM PC spec has
always been driven with 5 volt pulses. In the Win31 and early win95 days
Microsoft provided a driver that created a PWM signal from MM audio, and
actually pushed voice-quality audio through it.

The filters on PWM amplifiers are there to deal with the thermal effects of
their high frequency hash, not necessarily its direct effects on sound
quality.

Conventional hifi loudspeaker systems typically have a high frequency pole
somewhere between 16 KHz and 30 KHz. It acts like an integrator at 44 KHz.

"Arny Krueger" wrote in message news:5MWdnV-

In fact virtually all speakers do that right now.


It's not hifi, but the speaker that is part of the original IBM PC spec
has
always been driven with 5 volt pulses. In the Win31 and early win95 days
Microsoft provided a driver that created a PWM signal from MM audio, and
actually pushed voice-quality audio through it.

The filters on PWM amplifiers are there to deal with the thermal effects
of
their high frequency hash, not necessarily its direct effects on sound
quality.

Conventional hifi loudspeaker systems typically have a high frequency pole
somewhere between 16 KHz and 30 KHz. It acts like an integrator at 44 KHz.


Maybe in our choice of phrase, or my reading comprehension, but I took your
comment as the rather outrageous concept that " this is in effect what all
speakers are doing now in normal usage" . I thought it a little odd, even
for you !

;-)

geoff

"Arny Krueger" wrote in message news:5MWdnV-

In fact virtually all speakers do that right now.


It's not hifi, but the speaker that is part of the original IBM PC spec
has
always been driven with 5 volt pulses. In the Win31 and early win95 days
Microsoft provided a driver that created a PWM signal from MM audio, and
actually pushed voice-quality audio through it.

The filters on PWM amplifiers are there to deal with the thermal effects
of
their high frequency hash, not necessarily its direct effects on sound
quality.

Conventional hifi loudspeaker systems typically have a high frequency pole
somewhere between 16 KHz and 30 KHz. It acts like an integrator at 44 KHz.


Maybe in our choice of phrase, or my reading comprehension, but I took your
comment as the rather outrageous concept that " this is in effect what all
speakers are doing now in normal usage" . I thought it a little odd, even
for you !

;-)

geoff

"Geoff Wood" -nospam wrote in message

"Arny Krueger" wrote in message news:5MWdnV-

In fact virtually all speakers do that right now.


It's not hifi, but the speaker that is part of the original IBM PC
spec has always been driven with 5 volt pulses. In the Win31 and
early win95 days Microsoft provided a driver that created a PWM
signal from MM audio, and actually pushed voice-quality audio
through it.

The filters on PWM amplifiers are there to deal with the thermal
effects of their high frequency hash, not necessarily its direct
effects on sound quality.

Conventional hifi loudspeaker systems typically have a high
frequency pole somewhere between 16 KHz and 30 KHz. It acts like an
integrator at 44 KHz.


Maybe in our choice of phrase, or my reading comprehension, but I
took your comment as the rather outrageous concept that " this is in
effect what all speakers are doing now in normal usage" . I thought
it a little odd, even for you !

;-)

That is in fact what I meant. In order to reproduce the "stairstep" samples
of a 44.1 KHz digital audio signal, reasonably flat response to no less than
132.3 KHz would be required. *lesser* (i.e., typical) speakers will strongly
tend to blend the samples together.

"Geoff Wood" -nospam wrote in message

"Arny Krueger" wrote in message news:5MWdnV-

In fact virtually all speakers do that right now.


It's not hifi, but the speaker that is part of the original IBM PC
spec has always been driven with 5 volt pulses. In the Win31 and
early win95 days Microsoft provided a driver that created a PWM
signal from MM audio, and actually pushed voice-quality audio
through it.

The filters on PWM amplifiers are there to deal with the thermal
effects of their high frequency hash, not necessarily its direct
effects on sound quality.

Conventional hifi loudspeaker systems typically have a high
frequency pole somewhere between 16 KHz and 30 KHz. It acts like an
integrator at 44 KHz.


Maybe in our choice of phrase, or my reading comprehension, but I
took your comment as the rather outrageous concept that " this is in
effect what all speakers are doing now in normal usage" . I thought
it a little odd, even for you !

;-)

That is in fact what I meant. In order to reproduce the "stairstep" samples
of a 44.1 KHz digital audio signal, reasonably flat response to no less than
132.3 KHz would be required. *lesser* (i.e., typical) speakers will strongly
tend to blend the samples together.

"Arny Krueger" wrote in message

That is in fact what I meant. In order to reproduce the "stairstep"
samples
of a 44.1 KHz digital audio signal, reasonably flat response to no less
than
132.3 KHz would be required. *lesser* (i.e., typical) speakers will
strongly
tend to blend the samples together.


.... in which case your D-A is severely broken, unless you've intentionally
disabled the reconstruction filter !

geoff

"Arny Krueger" wrote in message

That is in fact what I meant. In order to reproduce the "stairstep"
samples
of a 44.1 KHz digital audio signal, reasonably flat response to no less
than
132.3 KHz would be required. *lesser* (i.e., typical) speakers will
strongly
tend to blend the samples together.


.... in which case your D-A is severely broken, unless you've intentionally
disabled the reconstruction filter !

geoff

"Geoff Wood" -nospam wrote in message


"Arny Krueger" wrote in message

That is in fact what I meant. In order to reproduce the "stairstep"
samples of a 44.1 KHz digital audio signal, reasonably flat response
to no less than 132.3 KHz would be required. *lesser* (i.e.,
typical) speakers will strongly tend to blend the samples together.

... in which case your D-A is severely broken, unless you've
intentionally disabled the reconstruction filter !

In this day and age, the reconstruction filter is so tightly integrated into
the DAC chip that disabling it is not an option. I took this to be a
philosophical, not a practical discussion. There actually have been PC sound
cards that lacked a brick wall filter, AFAIK the SoundBlaster Pro was one
such card.

"Geoff Wood" -nospam wrote in message


"Arny Krueger" wrote in message

That is in fact what I meant. In order to reproduce the "stairstep"
samples of a 44.1 KHz digital audio signal, reasonably flat response
to no less than 132.3 KHz would be required. *lesser* (i.e.,
typical) speakers will strongly tend to blend the samples together.

... in which case your D-A is severely broken, unless you've
intentionally disabled the reconstruction filter !

In this day and age, the reconstruction filter is so tightly integrated into
the DAC chip that disabling it is not an option. I took this to be a
philosophical, not a practical discussion. There actually have been PC sound
cards that lacked a brick wall filter, AFAIK the SoundBlaster Pro was one
such card.

"Arny Krueger" wrote in message
...
The filters on PWM amplifiers are there to deal with the
thermal effects of
their high frequency hash, not necessarily its direct effects
on sound
quality.

There are also other issues. Three come to mind.

The first is FCC and CISPR emission limits. Sending a pulse
train, several volts in amplitude, with a carrier in the hundreds
of kHz, if not MHz, down ordinary speaker wire just can't be done
in a practical sense. With controlled slew rates (very lossy) it
might be possible to roll off the high end before the 30MHz
radiated template but the signal would probably still radiate
back into the power line and fail conducted EMI in the 150kHz and
up range.

The second issue is insulation erosion in the voice coil or
crossover networks due to corona or displacement currents . The
varnish typically used in very small gauge wire would have a
short lifetime due to displacement currents near the leadouts.
This was a severe problem with early motor drives. They switched
at low frequency (few kHz) and had slow rise/fall times. Post
filtering was unnecessary to meet EMI limits and would have added
additional loss. However, within a short time motor insulation
failures occurred even though the peak voltage stress was well
below the insulation rating. A simple LPF was all that was
needed.

The third issue is high frequency ringing due to the parasitics
of a long cable and the speaker networks. At the amp you may
have nice pulses but at the speaker lots of overshoot and ringing
which increases number two above.

"Arny Krueger" wrote in message
...
The filters on PWM amplifiers are there to deal with the
thermal effects of
their high frequency hash, not necessarily its direct effects
on sound
quality.

There are also other issues. Three come to mind.

The first is FCC and CISPR emission limits. Sending a pulse
train, several volts in amplitude, with a carrier in the hundreds
of kHz, if not MHz, down ordinary speaker wire just can't be done
in a practical sense. With controlled slew rates (very lossy) it
might be possible to roll off the high end before the 30MHz
radiated template but the signal would probably still radiate
back into the power line and fail conducted EMI in the 150kHz and
up range.

The second issue is insulation erosion in the voice coil or
crossover networks due to corona or displacement currents . The
varnish typically used in very small gauge wire would have a
short lifetime due to displacement currents near the leadouts.
This was a severe problem with early motor drives. They switched
at low frequency (few kHz) and had slow rise/fall times. Post
filtering was unnecessary to meet EMI limits and would have added
additional loss. However, within a short time motor insulation
failures occurred even though the peak voltage stress was well
below the insulation rating. A simple LPF was all that was
needed.

The third issue is high frequency ringing due to the parasitics
of a long cable and the speaker networks. At the amp you may
have nice pulses but at the speaker lots of overshoot and ringing
which increases number two above.

"Arny Krueger" wrote
... in which case your D-A is severely broken, unless you've
intentionally disabled the reconstruction filter !

In this day and age, the reconstruction filter is so tightly integrated
into
the DAC chip that disabling it is not an option. I took this to be a
philosophical, not a practical discussion. There actually have been PC
sound
cards that lacked a brick wall filter, AFAIK the SoundBlaster Pro was one
such card.

Hi Chaps,
I've actually done this myself - a college project, write an assembler
routine to generate an audio sinewave on a Z80 based dev system - the DAC
outputs were unfiltered (I could get a pretty crisp 2MHz full-scale
squarewave out of it), and with an 8-bit
staircase-pretending-to-be-a-sinewave at 1 KHz delivered to a 5" speaker, it
sounded reasonably clean. BTW, Radium has a tendency to ask odd questions -
i think the radiation has affected hid mind ;o)

Dave H.
(The engineer formerly known as Homeless)

"Arny Krueger" wrote
... in which case your D-A is severely broken, unless you've
intentionally disabled the reconstruction filter !

In this day and age, the reconstruction filter is so tightly integrated
into
the DAC chip that disabling it is not an option. I took this to be a
philosophical, not a practical discussion. There actually have been PC
sound
cards that lacked a brick wall filter, AFAIK the SoundBlaster Pro was one
such card.

Hi Chaps,
I've actually done this myself - a college project, write an assembler
routine to generate an audio sinewave on a Z80 based dev system - the DAC
outputs were unfiltered (I could get a pretty crisp 2MHz full-scale
squarewave out of it), and with an 8-bit
staircase-pretending-to-be-a-sinewave at 1 KHz delivered to a 5" speaker, it
sounded reasonably clean. BTW, Radium has a tendency to ask odd questions -
i think the radiation has affected hid mind ;o)

Dave H.
(The engineer formerly known as Homeless)

"Dave H." wrote in
message
"Arny Krueger" wrote
... in which case your D-A is severely broken, unless you've
intentionally disabled the reconstruction filter !

In this day and age, the reconstruction filter is so tightly
integrated into the DAC chip that disabling it is not an option. I
took this to be a philosophical, not a practical discussion. There
actually have been PC sound cards that lacked a brick wall filter,
AFAIK the SoundBlaster Pro was one such card.

Hi Chaps,
I've actually done this myself - a college project, write an
assembler routine to generate an audio sinewave on a Z80 based dev
system - the DAC outputs were unfiltered (I could get a pretty crisp
2MHz full-scale squarewave out of it), and with an 8-bit
staircase-pretending-to-be-a-sinewave at 1 KHz delivered to a 5"
speaker, it sounded reasonably clean.

Yes, that should work.

BTW, Radium has a tendency to
ask odd questions - i think the radiation has affected hid mind ;o)

Agreed. "Radium" should read a few good audio FAQ's instead of spinning his
wheels with all these snake oil web sites.

"Dave H." wrote in
message
"Arny Krueger" wrote
... in which case your D-A is severely broken, unless you've
intentionally disabled the reconstruction filter !

In this day and age, the reconstruction filter is so tightly
integrated into the DAC chip that disabling it is not an option. I
took this to be a philosophical, not a practical discussion. There
actually have been PC sound cards that lacked a brick wall filter,
AFAIK the SoundBlaster Pro was one such card.

Hi Chaps,
I've actually done this myself - a college project, write an
assembler routine to generate an audio sinewave on a Z80 based dev
system - the DAC outputs were unfiltered (I could get a pretty crisp
2MHz full-scale squarewave out of it), and with an 8-bit
staircase-pretending-to-be-a-sinewave at 1 KHz delivered to a 5"
speaker, it sounded reasonably clean.

Yes, that should work.

BTW, Radium has a tendency to
ask odd questions - i think the radiation has affected hid mind ;o)

Agreed. "Radium" should read a few good audio FAQ's instead of spinning his
wheels with all these snake oil web sites.