Is there some practical way to do this by doing something funky in the
feedback loop or something? Would there be considerable downsides wrt
the operation of the amplifier itself? Excessive thermal dissipation
in the amplifier output stages, for instance? Do SS amplifiers like
this already exist (for one reason or another), or would this be
relatively virgin territory?

(dangling entity) wrote in message . com...
Is there some practical way to do this by doing something funky in the
feedback loop or something? Would there be considerable downsides wrt
the operation of the amplifier itself? Excessive thermal dissipation
in the amplifier output stages, for instance? Do SS amplifiers like
this already exist (for one reason or another), or would this be
relatively virgin territory?

Use negative feedback of the output current to acheive a positive
output resistance. Use positive feedback to get a negative output
resistance.

The output current is preferrably sensed with a small, low-inductive
(~0.1 ohms) resistor between the speaker and the ground.

Might I ask why you want this?

(dangling entity) wrote in message . com...
Is there some practical way to do this by doing something funky in the
feedback loop or something? Would there be considerable downsides wrt
the operation of the amplifier itself? Excessive thermal dissipation
in the amplifier output stages, for instance? Do SS amplifiers like
this already exist (for one reason or another), or would this be
relatively virgin territory?

Use negative feedback of the output current to acheive a positive
output resistance. Use positive feedback to get a negative output
resistance.

The output current is preferrably sensed with a small, low-inductive
(~0.1 ohms) resistor between the speaker and the ground.

Might I ask why you want this?

(dangling entity) wrote in message . com...
Is there some practical way to do this by doing something funky in the
feedback loop or something? Would there be considerable downsides wrt
the operation of the amplifier itself? Excessive thermal dissipation
in the amplifier output stages, for instance? Do SS amplifiers like
this already exist (for one reason or another), or would this be
relatively virgin territory?

Use negative feedback of the output current to acheive a positive
output resistance. Use positive feedback to get a negative output
resistance.

The output current is preferrably sensed with a small, low-inductive
(~0.1 ohms) resistor between the speaker and the ground.

Might I ask why you want this?

(dangling entity) wrote in message . com...
Is there some practical way to do this by doing something funky in the
feedback loop or something? Would there be considerable downsides wrt
the operation of the amplifier itself? Excessive thermal dissipation
in the amplifier output stages, for instance? Do SS amplifiers like
this already exist (for one reason or another), or would this be
relatively virgin territory?

Use negative feedback of the output current to acheive a positive
output resistance. Use positive feedback to get a negative output
resistance.

The output current is preferrably sensed with a small, low-inductive
(~0.1 ohms) resistor between the speaker and the ground.

Might I ask why you want this?

"dangling entity" wrote in message
om

Is there some practical way to do this by doing something funky in the
feedback loop or something? Would there be considerable downsides wrt
the operation of the amplifier itself? Excessive thermal dissipation
in the amplifier output stages, for instance? Do SS amplifiers like
this already exist (for one reason or another), or would this be
relatively virgin territory?

Just put a resistor in series with the speaker. Cheap, safe, easy to
engineer.

Note that this amounts to ruining the engineering of the bass part of the
speaker system.

"dangling entity" wrote in message
om

Is there some practical way to do this by doing something funky in the
feedback loop or something? Would there be considerable downsides wrt
the operation of the amplifier itself? Excessive thermal dissipation
in the amplifier output stages, for instance? Do SS amplifiers like
this already exist (for one reason or another), or would this be
relatively virgin territory?

Just put a resistor in series with the speaker. Cheap, safe, easy to
engineer.

Note that this amounts to ruining the engineering of the bass part of the
speaker system.

"dangling entity" wrote in message
om

Is there some practical way to do this by doing something funky in the
feedback loop or something? Would there be considerable downsides wrt
the operation of the amplifier itself? Excessive thermal dissipation
in the amplifier output stages, for instance? Do SS amplifiers like
this already exist (for one reason or another), or would this be
relatively virgin territory?

Just put a resistor in series with the speaker. Cheap, safe, easy to
engineer.

Note that this amounts to ruining the engineering of the bass part of the
speaker system.

"dangling entity" wrote in message
om

Is there some practical way to do this by doing something funky in the
feedback loop or something? Would there be considerable downsides wrt
the operation of the amplifier itself? Excessive thermal dissipation
in the amplifier output stages, for instance? Do SS amplifiers like
this already exist (for one reason or another), or would this be
relatively virgin territory?

Just put a resistor in series with the speaker. Cheap, safe, easy to
engineer.

Note that this amounts to ruining the engineering of the bass part of the
speaker system.

dangling entity wrote:

Is there some practical way to do this by doing something funky in the
feedback loop or something? Would there be considerable downsides wrt
the operation of the amplifier itself? Excessive thermal dissipation
in the amplifier output stages, for instance? Do SS amplifiers like
this already exist (for one reason or another), or would this be
relatively virgin territory?


Use a current amplifier instead of a voltage amplifier. An ideal V source has
zero output Z. An ideal I source has infinite output Z. I can not see a reason
to do this.

dangling entity wrote:

Is there some practical way to do this by doing something funky in the
feedback loop or something? Would there be considerable downsides wrt
the operation of the amplifier itself? Excessive thermal dissipation
in the amplifier output stages, for instance? Do SS amplifiers like
this already exist (for one reason or another), or would this be
relatively virgin territory?


Use a current amplifier instead of a voltage amplifier. An ideal V source has
zero output Z. An ideal I source has infinite output Z. I can not see a reason
to do this.

dangling entity wrote:

Is there some practical way to do this by doing something funky in the
feedback loop or something? Would there be considerable downsides wrt
the operation of the amplifier itself? Excessive thermal dissipation
in the amplifier output stages, for instance? Do SS amplifiers like
this already exist (for one reason or another), or would this be
relatively virgin territory?


Use a current amplifier instead of a voltage amplifier. An ideal V source has
zero output Z. An ideal I source has infinite output Z. I can not see a reason
to do this.

dangling entity wrote:

Is there some practical way to do this by doing something funky in the
feedback loop or something? Would there be considerable downsides wrt
the operation of the amplifier itself? Excessive thermal dissipation
in the amplifier output stages, for instance? Do SS amplifiers like
this already exist (for one reason or another), or would this be
relatively virgin territory?


Use a current amplifier instead of a voltage amplifier. An ideal V source has
zero output Z. An ideal I source has infinite output Z. I can not see a reason
to do this.

"Arny Krueger" wrote in message ...
"dangling entity" wrote in message
om

Is there some practical way to do this by doing something funky in the
feedback loop or something? Would there be considerable downsides wrt
the operation of the amplifier itself? Excessive thermal dissipation
in the amplifier output stages, for instance? Do SS amplifiers like
this already exist (for one reason or another), or would this be
relatively virgin territory?

Just put a resistor in series with the speaker. Cheap, safe, easy to
engineer.

Note that this amounts to ruining the engineering of the bass part of the
speaker system.

Yes, a resistor would do the same thing, but I am still intrigued
about ways the amplifier could present this load inherently. Maybe it
doesn't make a difference, either way, as the additional heat
dissipation is unavoidable no matter how you do it (I'm guessing)?

Thank you both, Arnie and Don, for your initial responses. Do you
have anything else to add wrt the additional questions I posed- any
downsides to an amplifier operating with the additional negative
feedback so as to impose the desired output impedance, will excessive
thermal dissipation in the output stages then become an issue, and
have there ever been SS amplifiers that fit this description?

"Arny Krueger" wrote in message ...
"dangling entity" wrote in message
om

Is there some practical way to do this by doing something funky in the
feedback loop or something? Would there be considerable downsides wrt
the operation of the amplifier itself? Excessive thermal dissipation
in the amplifier output stages, for instance? Do SS amplifiers like
this already exist (for one reason or another), or would this be
relatively virgin territory?

Just put a resistor in series with the speaker. Cheap, safe, easy to
engineer.

Note that this amounts to ruining the engineering of the bass part of the
speaker system.

Yes, a resistor would do the same thing, but I am still intrigued
about ways the amplifier could present this load inherently. Maybe it
doesn't make a difference, either way, as the additional heat
dissipation is unavoidable no matter how you do it (I'm guessing)?

Thank you both, Arnie and Don, for your initial responses. Do you
have anything else to add wrt the additional questions I posed- any
downsides to an amplifier operating with the additional negative
feedback so as to impose the desired output impedance, will excessive
thermal dissipation in the output stages then become an issue, and
have there ever been SS amplifiers that fit this description?

"Arny Krueger" wrote in message ...
"dangling entity" wrote in message
om

Is there some practical way to do this by doing something funky in the
feedback loop or something? Would there be considerable downsides wrt
the operation of the amplifier itself? Excessive thermal dissipation
in the amplifier output stages, for instance? Do SS amplifiers like
this already exist (for one reason or another), or would this be
relatively virgin territory?

Just put a resistor in series with the speaker. Cheap, safe, easy to
engineer.

Note that this amounts to ruining the engineering of the bass part of the
speaker system.

Yes, a resistor would do the same thing, but I am still intrigued
about ways the amplifier could present this load inherently. Maybe it
doesn't make a difference, either way, as the additional heat
dissipation is unavoidable no matter how you do it (I'm guessing)?

Thank you both, Arnie and Don, for your initial responses. Do you
have anything else to add wrt the additional questions I posed- any
downsides to an amplifier operating with the additional negative
feedback so as to impose the desired output impedance, will excessive
thermal dissipation in the output stages then become an issue, and
have there ever been SS amplifiers that fit this description?

"Arny Krueger" wrote in message ...
"dangling entity" wrote in message
om

Is there some practical way to do this by doing something funky in the
feedback loop or something? Would there be considerable downsides wrt
the operation of the amplifier itself? Excessive thermal dissipation
in the amplifier output stages, for instance? Do SS amplifiers like
this already exist (for one reason or another), or would this be
relatively virgin territory?

Just put a resistor in series with the speaker. Cheap, safe, easy to
engineer.

Note that this amounts to ruining the engineering of the bass part of the
speaker system.

Yes, a resistor would do the same thing, but I am still intrigued
about ways the amplifier could present this load inherently. Maybe it
doesn't make a difference, either way, as the additional heat
dissipation is unavoidable no matter how you do it (I'm guessing)?

Thank you both, Arnie and Don, for your initial responses. Do you
have anything else to add wrt the additional questions I posed- any
downsides to an amplifier operating with the additional negative
feedback so as to impose the desired output impedance, will excessive
thermal dissipation in the output stages then become an issue, and
have there ever been SS amplifiers that fit this description?

(Svante) wrote in message . com...
(dangling entity) wrote in message . com...

Might I ask why you want this?

Well, I guess my willingness to answer this will be quite dependent on
the answer to "if this has been done before".

(Svante) wrote in message . com...
(dangling entity) wrote in message . com...

Might I ask why you want this?

Well, I guess my willingness to answer this will be quite dependent on
the answer to "if this has been done before".

(Svante) wrote in message . com...
(dangling entity) wrote in message . com...

Might I ask why you want this?

Well, I guess my willingness to answer this will be quite dependent on
the answer to "if this has been done before".

(Svante) wrote in message . com...
(dangling entity) wrote in message . com...

Might I ask why you want this?

Well, I guess my willingness to answer this will be quite dependent on
the answer to "if this has been done before".

"dangling entity" wrote in message
om...
Is there some practical way to do this by doing something funky in the
feedback loop or something?

I wouldn't mess with the feedback loop. The easiest and most predictable way
tou increase the output impedance of an existing amplifier would be to put a
resistor in series with the load. A solid state amplifier using negative
feedback can typically be considered to have nearly zero output impedance,
so the output impedance can simply be approximated to be the series resistor
itself.

Would there be considerable downsides wrt
the operation of the amplifier itself?

Putting a resistor in series with the load would make life a lot easier for
the amp.

Excessive thermal dissipation
in the amplifier output stages, for instance?

Only in the series resistor. You need to select the right wattage resistor:

P = I^2 * R

where P is the power that must be dissipated by the resistor, I is the
current in the resistor, and R is the resistor value.

Do SS amplifiers like
this already exist (for one reason or another), or would this be
relatively virgin territory?

They do make so-called constant-current amplifiers, but not any for audio
applications AFAIK. Most are of the constant-voltage type.

For what it's worth, if you happen to have a high-impedance speaker, you can
drive it with any solid state amplifier without any ill effects. The
amplifier won't mind the lighter load.

P = E^2 / R

where P is the power dissipated in the speaker, E is voltage across the
speaker terminals (usually measured in terms of AC RMS volts), and R is the
nominal speaker impedance. For a given constant voltage, you can see that
the power dissipated in the speaker is inversely proportional to the speaker
impedance.

Why do you want a high output impedance? What impedance were you
considering?

"dangling entity" wrote in message
om...
Is there some practical way to do this by doing something funky in the
feedback loop or something?

I wouldn't mess with the feedback loop. The easiest and most predictable way
tou increase the output impedance of an existing amplifier would be to put a
resistor in series with the load. A solid state amplifier using negative
feedback can typically be considered to have nearly zero output impedance,
so the output impedance can simply be approximated to be the series resistor
itself.

Would there be considerable downsides wrt
the operation of the amplifier itself?

Putting a resistor in series with the load would make life a lot easier for
the amp.

Excessive thermal dissipation
in the amplifier output stages, for instance?

Only in the series resistor. You need to select the right wattage resistor:

P = I^2 * R

where P is the power that must be dissipated by the resistor, I is the
current in the resistor, and R is the resistor value.

Do SS amplifiers like
this already exist (for one reason or another), or would this be
relatively virgin territory?

They do make so-called constant-current amplifiers, but not any for audio
applications AFAIK. Most are of the constant-voltage type.

For what it's worth, if you happen to have a high-impedance speaker, you can
drive it with any solid state amplifier without any ill effects. The
amplifier won't mind the lighter load.

P = E^2 / R

where P is the power dissipated in the speaker, E is voltage across the
speaker terminals (usually measured in terms of AC RMS volts), and R is the
nominal speaker impedance. For a given constant voltage, you can see that
the power dissipated in the speaker is inversely proportional to the speaker
impedance.

Why do you want a high output impedance? What impedance were you
considering?

"dangling entity" wrote in message
om...
Is there some practical way to do this by doing something funky in the
feedback loop or something?

I wouldn't mess with the feedback loop. The easiest and most predictable way
tou increase the output impedance of an existing amplifier would be to put a
resistor in series with the load. A solid state amplifier using negative
feedback can typically be considered to have nearly zero output impedance,
so the output impedance can simply be approximated to be the series resistor
itself.

Would there be considerable downsides wrt
the operation of the amplifier itself?

Putting a resistor in series with the load would make life a lot easier for
the amp.

Excessive thermal dissipation
in the amplifier output stages, for instance?

Only in the series resistor. You need to select the right wattage resistor:

P = I^2 * R

where P is the power that must be dissipated by the resistor, I is the
current in the resistor, and R is the resistor value.

Do SS amplifiers like
this already exist (for one reason or another), or would this be
relatively virgin territory?

They do make so-called constant-current amplifiers, but not any for audio
applications AFAIK. Most are of the constant-voltage type.

For what it's worth, if you happen to have a high-impedance speaker, you can
drive it with any solid state amplifier without any ill effects. The
amplifier won't mind the lighter load.

P = E^2 / R

where P is the power dissipated in the speaker, E is voltage across the
speaker terminals (usually measured in terms of AC RMS volts), and R is the
nominal speaker impedance. For a given constant voltage, you can see that
the power dissipated in the speaker is inversely proportional to the speaker
impedance.

Why do you want a high output impedance? What impedance were you
considering?

"dangling entity" wrote in message
om...
Is there some practical way to do this by doing something funky in the
feedback loop or something?

I wouldn't mess with the feedback loop. The easiest and most predictable way
tou increase the output impedance of an existing amplifier would be to put a
resistor in series with the load. A solid state amplifier using negative
feedback can typically be considered to have nearly zero output impedance,
so the output impedance can simply be approximated to be the series resistor
itself.

Would there be considerable downsides wrt
the operation of the amplifier itself?

Putting a resistor in series with the load would make life a lot easier for
the amp.

Excessive thermal dissipation
in the amplifier output stages, for instance?

Only in the series resistor. You need to select the right wattage resistor:

P = I^2 * R

where P is the power that must be dissipated by the resistor, I is the
current in the resistor, and R is the resistor value.

Do SS amplifiers like
this already exist (for one reason or another), or would this be
relatively virgin territory?

They do make so-called constant-current amplifiers, but not any for audio
applications AFAIK. Most are of the constant-voltage type.

For what it's worth, if you happen to have a high-impedance speaker, you can
drive it with any solid state amplifier without any ill effects. The
amplifier won't mind the lighter load.

P = E^2 / R

where P is the power dissipated in the speaker, E is voltage across the
speaker terminals (usually measured in terms of AC RMS volts), and R is the
nominal speaker impedance. For a given constant voltage, you can see that
the power dissipated in the speaker is inversely proportional to the speaker
impedance.

Why do you want a high output impedance? What impedance were you
considering?

"Arny Krueger" wrote in message ...
"dangling entity" wrote in message
om

Is there some practical way to do this by doing something funky in the
feedback loop or something? Would there be considerable downsides wrt
the operation of the amplifier itself? Excessive thermal dissipation
in the amplifier output stages, for instance? Do SS amplifiers like
this already exist (for one reason or another), or would this be
relatively virgin territory?

Just put a resistor in series with the speaker. Cheap, safe, easy to
engineer.

Note that this amounts to ruining the engineering of the bass part of the
speaker system.

....or it can be *part of* the engineering. A series resistance is a
way to raise Qts.

"Arny Krueger" wrote in message ...
"dangling entity" wrote in message
om

Is there some practical way to do this by doing something funky in the
feedback loop or something? Would there be considerable downsides wrt
the operation of the amplifier itself? Excessive thermal dissipation
in the amplifier output stages, for instance? Do SS amplifiers like
this already exist (for one reason or another), or would this be
relatively virgin territory?

Just put a resistor in series with the speaker. Cheap, safe, easy to
engineer.

Note that this amounts to ruining the engineering of the bass part of the
speaker system.

....or it can be *part of* the engineering. A series resistance is a
way to raise Qts.

"Arny Krueger" wrote in message ...
"dangling entity" wrote in message
om

Is there some practical way to do this by doing something funky in the
feedback loop or something? Would there be considerable downsides wrt
the operation of the amplifier itself? Excessive thermal dissipation
in the amplifier output stages, for instance? Do SS amplifiers like
this already exist (for one reason or another), or would this be
relatively virgin territory?

Just put a resistor in series with the speaker. Cheap, safe, easy to
engineer.

Note that this amounts to ruining the engineering of the bass part of the
speaker system.

....or it can be *part of* the engineering. A series resistance is a
way to raise Qts.

"Arny Krueger" wrote in message ...
"dangling entity" wrote in message
om

Is there some practical way to do this by doing something funky in the
feedback loop or something? Would there be considerable downsides wrt
the operation of the amplifier itself? Excessive thermal dissipation
in the amplifier output stages, for instance? Do SS amplifiers like
this already exist (for one reason or another), or would this be
relatively virgin territory?

Just put a resistor in series with the speaker. Cheap, safe, easy to
engineer.

Note that this amounts to ruining the engineering of the bass part of the
speaker system.

....or it can be *part of* the engineering. A series resistance is a
way to raise Qts.

dangling entity wrote:

"Arny Krueger" wrote in message ...
"dangling entity" wrote in message
om

Is there some practical way to do this by doing something funky in the
feedback loop or something? Would there be considerable downsides wrt
the operation of the amplifier itself? Excessive thermal dissipation
in the amplifier output stages, for instance? Do SS amplifiers like
this already exist (for one reason or another), or would this be
relatively virgin territory?

Just put a resistor in series with the speaker. Cheap, safe, easy to
engineer.

Note that this amounts to ruining the engineering of the bass part of the
speaker system.

Yes, a resistor would do the same thing, but I am still intrigued
about ways the amplifier could present this load inherently. Maybe it
doesn't make a difference, either way, as the additional heat
dissipation is unavoidable no matter how you do it (I'm guessing)?

Thank you both, Arnie and Don, for your initial responses. Do you
have anything else to add wrt the additional questions I posed- any
downsides to an amplifier operating with the additional negative
feedback so as to impose the desired output impedance,...

Increased negative feedback in a *voltage* amplifier _lowers_ the output Z, not
raises it.

Make the speaker coil the "feedback resistor." That will transform the
configuration into a current source as far as the load is concerned. (Naturally
the other resistor -- the one from the inverting input to ground -- needs to be
adjusted too to get the correct gain.) I'm not going to do your stability
analysis for you. Watch out.

...will excessive
thermal dissipation in the output stages then become an issue, and
have there ever been SS amplifiers that fit this description?

You might want to google "current conveyor."

http://www.macs.ece.mcgill.ca/~rober...or_History.pdf
http://www.macs.ece.mcgill.ca/~rober...onveyor_90.pdf


The mirror to the voltage amp, which has high input Z and low output Z, is the
*current* amplifier, which has low input Z and high output Z.


If you are going to post to the usenet, you need a chaos generator:
http://www.sharjah.ac.ae/courseware/...olimanieee.pdf

dangling entity wrote:

"Arny Krueger" wrote in message ...
"dangling entity" wrote in message
om

Is there some practical way to do this by doing something funky in the
feedback loop or something? Would there be considerable downsides wrt
the operation of the amplifier itself? Excessive thermal dissipation
in the amplifier output stages, for instance? Do SS amplifiers like
this already exist (for one reason or another), or would this be
relatively virgin territory?

Just put a resistor in series with the speaker. Cheap, safe, easy to
engineer.

Note that this amounts to ruining the engineering of the bass part of the
speaker system.

Yes, a resistor would do the same thing, but I am still intrigued
about ways the amplifier could present this load inherently. Maybe it
doesn't make a difference, either way, as the additional heat
dissipation is unavoidable no matter how you do it (I'm guessing)?

Thank you both, Arnie and Don, for your initial responses. Do you
have anything else to add wrt the additional questions I posed- any
downsides to an amplifier operating with the additional negative
feedback so as to impose the desired output impedance,...

Increased negative feedback in a *voltage* amplifier _lowers_ the output Z, not
raises it.

Make the speaker coil the "feedback resistor." That will transform the
configuration into a current source as far as the load is concerned. (Naturally
the other resistor -- the one from the inverting input to ground -- needs to be
adjusted too to get the correct gain.) I'm not going to do your stability
analysis for you. Watch out.

...will excessive
thermal dissipation in the output stages then become an issue, and
have there ever been SS amplifiers that fit this description?

You might want to google "current conveyor."

http://www.macs.ece.mcgill.ca/~rober...or_History.pdf
http://www.macs.ece.mcgill.ca/~rober...onveyor_90.pdf


The mirror to the voltage amp, which has high input Z and low output Z, is the
*current* amplifier, which has low input Z and high output Z.


If you are going to post to the usenet, you need a chaos generator:
http://www.sharjah.ac.ae/courseware/...olimanieee.pdf

dangling entity wrote:

"Arny Krueger" wrote in message ...
"dangling entity" wrote in message
om

Is there some practical way to do this by doing something funky in the
feedback loop or something? Would there be considerable downsides wrt
the operation of the amplifier itself? Excessive thermal dissipation
in the amplifier output stages, for instance? Do SS amplifiers like
this already exist (for one reason or another), or would this be
relatively virgin territory?

Just put a resistor in series with the speaker. Cheap, safe, easy to
engineer.

Note that this amounts to ruining the engineering of the bass part of the
speaker system.

Yes, a resistor would do the same thing, but I am still intrigued
about ways the amplifier could present this load inherently. Maybe it
doesn't make a difference, either way, as the additional heat
dissipation is unavoidable no matter how you do it (I'm guessing)?

Thank you both, Arnie and Don, for your initial responses. Do you
have anything else to add wrt the additional questions I posed- any
downsides to an amplifier operating with the additional negative
feedback so as to impose the desired output impedance,...

Increased negative feedback in a *voltage* amplifier _lowers_ the output Z, not
raises it.

Make the speaker coil the "feedback resistor." That will transform the
configuration into a current source as far as the load is concerned. (Naturally
the other resistor -- the one from the inverting input to ground -- needs to be
adjusted too to get the correct gain.) I'm not going to do your stability
analysis for you. Watch out.

...will excessive
thermal dissipation in the output stages then become an issue, and
have there ever been SS amplifiers that fit this description?

You might want to google "current conveyor."

http://www.macs.ece.mcgill.ca/~rober...or_History.pdf
http://www.macs.ece.mcgill.ca/~rober...onveyor_90.pdf


The mirror to the voltage amp, which has high input Z and low output Z, is the
*current* amplifier, which has low input Z and high output Z.


If you are going to post to the usenet, you need a chaos generator:
http://www.sharjah.ac.ae/courseware/...olimanieee.pdf

dangling entity wrote:

"Arny Krueger" wrote in message ...
"dangling entity" wrote in message
om

Is there some practical way to do this by doing something funky in the
feedback loop or something? Would there be considerable downsides wrt
the operation of the amplifier itself? Excessive thermal dissipation
in the amplifier output stages, for instance? Do SS amplifiers like
this already exist (for one reason or another), or would this be
relatively virgin territory?

Just put a resistor in series with the speaker. Cheap, safe, easy to
engineer.

Note that this amounts to ruining the engineering of the bass part of the
speaker system.

Yes, a resistor would do the same thing, but I am still intrigued
about ways the amplifier could present this load inherently. Maybe it
doesn't make a difference, either way, as the additional heat
dissipation is unavoidable no matter how you do it (I'm guessing)?

Thank you both, Arnie and Don, for your initial responses. Do you
have anything else to add wrt the additional questions I posed- any
downsides to an amplifier operating with the additional negative
feedback so as to impose the desired output impedance,...

Increased negative feedback in a *voltage* amplifier _lowers_ the output Z, not
raises it.

Make the speaker coil the "feedback resistor." That will transform the
configuration into a current source as far as the load is concerned. (Naturally
the other resistor -- the one from the inverting input to ground -- needs to be
adjusted too to get the correct gain.) I'm not going to do your stability
analysis for you. Watch out.

...will excessive
thermal dissipation in the output stages then become an issue, and
have there ever been SS amplifiers that fit this description?

You might want to google "current conveyor."

http://www.macs.ece.mcgill.ca/~rober...or_History.pdf
http://www.macs.ece.mcgill.ca/~rober...onveyor_90.pdf


The mirror to the voltage amp, which has high input Z and low output Z, is the
*current* amplifier, which has low input Z and high output Z.


If you are going to post to the usenet, you need a chaos generator:
http://www.sharjah.ac.ae/courseware/...olimanieee.pdf

gwhite wrote in message ...
dangling entity wrote:

Is there some practical way to do this by doing something funky in the
feedback loop or something? Would there be considerable downsides wrt
the operation of the amplifier itself? Excessive thermal dissipation
in the amplifier output stages, for instance? Do SS amplifiers like
this already exist (for one reason or another), or would this be
relatively virgin territory?


Use a current amplifier instead of a voltage amplifier. An ideal V source has
zero output Z. An ideal I source has infinite output Z. I can not see a reason
to do this.

Well, I don't think I really wanted to go *all* the way to the other
extreme- *infinite Z*. Just a short ways from where a voltage
amplifier already is- maybe 6 ohms to drive a home speaker driver?

gwhite wrote in message ...
dangling entity wrote:

Is there some practical way to do this by doing something funky in the
feedback loop or something? Would there be considerable downsides wrt
the operation of the amplifier itself? Excessive thermal dissipation
in the amplifier output stages, for instance? Do SS amplifiers like
this already exist (for one reason or another), or would this be
relatively virgin territory?


Use a current amplifier instead of a voltage amplifier. An ideal V source has
zero output Z. An ideal I source has infinite output Z. I can not see a reason
to do this.

Well, I don't think I really wanted to go *all* the way to the other
extreme- *infinite Z*. Just a short ways from where a voltage
amplifier already is- maybe 6 ohms to drive a home speaker driver?

gwhite wrote in message ...
dangling entity wrote:

Is there some practical way to do this by doing something funky in the
feedback loop or something? Would there be considerable downsides wrt
the operation of the amplifier itself? Excessive thermal dissipation
in the amplifier output stages, for instance? Do SS amplifiers like
this already exist (for one reason or another), or would this be
relatively virgin territory?


Use a current amplifier instead of a voltage amplifier. An ideal V source has
zero output Z. An ideal I source has infinite output Z. I can not see a reason
to do this.

Well, I don't think I really wanted to go *all* the way to the other
extreme- *infinite Z*. Just a short ways from where a voltage
amplifier already is- maybe 6 ohms to drive a home speaker driver?

gwhite wrote in message ...
dangling entity wrote:

Is there some practical way to do this by doing something funky in the
feedback loop or something? Would there be considerable downsides wrt
the operation of the amplifier itself? Excessive thermal dissipation
in the amplifier output stages, for instance? Do SS amplifiers like
this already exist (for one reason or another), or would this be
relatively virgin territory?


Use a current amplifier instead of a voltage amplifier. An ideal V source has
zero output Z. An ideal I source has infinite output Z. I can not see a reason
to do this.

Well, I don't think I really wanted to go *all* the way to the other
extreme- *infinite Z*. Just a short ways from where a voltage
amplifier already is- maybe 6 ohms to drive a home speaker driver?

(dangling entity) wrote in message . com...
Is there some practical way to do this by doing something funky in the
feedback loop or something? Would there be considerable downsides wrt
the operation of the amplifier itself? Excessive thermal dissipation
in the amplifier output stages, for instance? Do SS amplifiers like
this already exist (for one reason or another), or would this be
relatively virgin territory?


Are you looking for something to drive a novel design of low audio (or
sub-audio) frequency electrical current to air pressure transducer,
perhaps novel enough that conventional terms such as speaker and
subwoofer are inadequate? If it's something you may seek a patent
for, and therefore wish to withhold details, can you at least reveal
input impedence and power requirements? Ordinarily wouldn't lower amp
output impedence be better from a standpoint of damping factor and not
being subjected to too low of a load impedence (i.e., too great a
load, drawing too much current)?

(dangling entity) wrote in message . com...
Is there some practical way to do this by doing something funky in the
feedback loop or something? Would there be considerable downsides wrt
the operation of the amplifier itself? Excessive thermal dissipation
in the amplifier output stages, for instance? Do SS amplifiers like
this already exist (for one reason or another), or would this be
relatively virgin territory?


Are you looking for something to drive a novel design of low audio (or
sub-audio) frequency electrical current to air pressure transducer,
perhaps novel enough that conventional terms such as speaker and
subwoofer are inadequate? If it's something you may seek a patent
for, and therefore wish to withhold details, can you at least reveal
input impedence and power requirements? Ordinarily wouldn't lower amp
output impedence be better from a standpoint of damping factor and not
being subjected to too low of a load impedence (i.e., too great a
load, drawing too much current)?

(dangling entity) wrote in message . com...
Is there some practical way to do this by doing something funky in the
feedback loop or something? Would there be considerable downsides wrt
the operation of the amplifier itself? Excessive thermal dissipation
in the amplifier output stages, for instance? Do SS amplifiers like
this already exist (for one reason or another), or would this be
relatively virgin territory?


Are you looking for something to drive a novel design of low audio (or
sub-audio) frequency electrical current to air pressure transducer,
perhaps novel enough that conventional terms such as speaker and
subwoofer are inadequate? If it's something you may seek a patent
for, and therefore wish to withhold details, can you at least reveal
input impedence and power requirements? Ordinarily wouldn't lower amp
output impedence be better from a standpoint of damping factor and not
being subjected to too low of a load impedence (i.e., too great a
load, drawing too much current)?