Reply
 
Thread Tools Display Modes
  #1   Report Post  
Radium
 
Posts: n/a
Default An Actual Digital Speaker??

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.
  #6   Report Post  
Arny Krueger
 
Posts: n/a
Default An Actual Digital Speaker??

"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.


  #7   Report Post  
Arny Krueger
 
Posts: n/a
Default An Actual Digital Speaker??

"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.


  #8   Report Post  
Geoff Wood
 
Posts: n/a
Default An Actual Digital Speaker??


"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


  #9   Report Post  
Geoff Wood
 
Posts: n/a
Default An Actual Digital Speaker??


"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


  #10   Report Post  
Geoff Wood
 
Posts: n/a
Default An Actual Digital Speaker??


"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




  #11   Report Post  
Geoff Wood
 
Posts: n/a
Default An Actual Digital Speaker??


"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


  #12   Report Post  
Arny Krueger
 
Posts: n/a
Default An Actual Digital Speaker??

"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.


  #13   Report Post  
Arny Krueger
 
Posts: n/a
Default An Actual Digital Speaker??

"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.


  #14   Report Post  
Geoff Wood
 
Posts: n/a
Default An Actual Digital Speaker??


"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


  #15   Report Post  
Geoff Wood
 
Posts: n/a
Default An Actual Digital Speaker??


"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




  #16   Report Post  
Arny Krueger
 
Posts: n/a
Default An Actual Digital Speaker??

"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.


  #17   Report Post  
Arny Krueger
 
Posts: n/a
Default An Actual Digital Speaker??

"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.


  #18   Report Post  
Geoff Wood
 
Posts: n/a
Default An Actual Digital Speaker??


"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


  #19   Report Post  
Geoff Wood
 
Posts: n/a
Default An Actual Digital Speaker??


"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


  #20   Report Post  
Arny Krueger
 
Posts: n/a
Default An Actual Digital Speaker??

"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.




  #21   Report Post  
Arny Krueger
 
Posts: n/a
Default An Actual Digital Speaker??

"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.


  #22   Report Post  
Rusty Boudreaux
 
Posts: n/a
Default An Actual Digital Speaker??

"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.


  #23   Report Post  
Rusty Boudreaux
 
Posts: n/a
Default An Actual Digital Speaker??

"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.


  #24   Report Post  
Dave H.
 
Posts: n/a
Default An Actual Digital Speaker??


"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)


  #25   Report Post  
Dave H.
 
Posts: n/a
Default An Actual Digital Speaker??


"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)




  #26   Report Post  
Arny Krueger
 
Posts: n/a
Default An Actual Digital Speaker??

"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.


  #27   Report Post  
Arny Krueger
 
Posts: n/a
Default An Actual Digital Speaker??

"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.


Reply
Thread Tools
Display Modes

Posting Rules

Smilies are On
[IMG] code is On
HTML code is Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
rec.audio.car FAQ (Part 4/5) Ian D. Bjorhovde Car Audio 0 March 6th 04 07:54 AM
rec.audio.car FAQ (Part 3/5) Ian D. Bjorhovde Car Audio 0 March 6th 04 07:54 AM
Sony Digital Amps (and SACD) vs. Sony Analog Amps banspeakerports High End Audio 0 February 8th 04 07:18 PM
Comments about Blind Testing watch king High End Audio 24 January 28th 04 05:03 PM
Question re. Speaker Sensitvity Bruce J. Richman High End Audio 0 August 6th 03 07:29 AM


All times are GMT +1. The time now is 02:57 PM.

Powered by: vBulletin
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 AudioBanter.com.
The comments are property of their posters.
 

About Us

"It's about Audio and hi-fi"