Tekton Design 2-Ohm Pendragons?

[Boomzilla]

Probably need a “pro” amp to drive them…. Anyone heard them?

[butchgo]

Take a look.

www.youtube.com/watch?v=9KJKNmPp9lM

[DavidR]

Don't get your pants all wet over it. Mids will still suffer with a design like that.

Kappa 9 speakers dip to 1 ohm. It doesn't make them sound any better.

You can remove the 'tank' circuit from an AR9 and make them 2 ohm (and dip lower) but they don't sound better and most people who have tried this go back to using the tank circuit. Probably because their amps are overworking, overheating and no longer sounding good.

[housetech]

They should be called the amp killer.
You can bet a bunch of young & clueless will be replacing the speakers and their amp in a short time.

[DavidR]

Kappa 9 speakers already have that designation; but, yeah.

[jjkessler]

I wonder if the XPA-1L could safely drive them

[jjkessler]

Nevermind, I guess not according to the manual

Minimum Recommended Load Impedance:4 Ohms (which equals one 4 Ohm load or two paralleled 8 Ohm loads)

[Boomzilla]

As I understand it, the greater the current through the woofer's voice coil, the tighter the control that the amplifier has on the load. And that, unless I'm mistaken, is why so many speaker makers these days sell 4-ohm speakers instead of the 8-ohm or 16-ohm models that were popular in earlier years. Class D amplifiers (that are rapidly coming into common usage) are more often capable of 2-ohm loads than other types. So 2-ohm capable amps + 2-ohm speakers at least theoretically offer tighter bass than speakers with less voice-coil current capability.

[DavidR]

If your talking damping factor then I don't think so. If an amp has a damping factor of 500 at 8 ohms it will be half with 4 ohms.

Tighter bass was achieved by Edgar Villchur in the 50's when he invented the acoustic suspension speaker. He went on to form Acoustic Research Inc. with Henry Kloss. The speakers he built and designed are still highly regarded and sell for good/lots of money. A good number of surviving AR3 and AR3a speakers end up in Japan. Many notable audio engineers, most of whom came from MIT, were employed by AR.

[Boomzilla]

Nope - Not talking damping factor (the ratio of the load impedance divided by the amplifier’s output impedance) or the type of driver enclosure and its contribution to the q of the driver, but rather the amount of current that can be supplied to the voice coil of the driver(s). Since there is a practical limit to the magnetic gauss that a magnet can supply, and since there is also a physical limit to voice-coil travel, the only practical way to more accurately increase the control over voice coil movement is to increase the current flow through the voice coil.

Even that is limited by cooling and by amplifier current delivery capability, but a lower voice coil impedance (given identical magnetic gauss and voice coil travel) results in more accurate voice coil control and reduces the effects of suspension compliance and enclosure tuning.

[DavidR]

sounds like a journey of its own

[405x5]

Jun 25, 2022 19:39:11 GMT -5 Boomzilla said:

Probably need a “pro” amp to drive them…. Anyone heard them?

I’ve got THE amp. that could drive those loudspeakers with ease. (Signature 400).
But would I??
I would not speculate without giving them a fair listen, but that driver array layout is in conflict with most of the guidance I trust from the engineers I’ve followed

[novisnick]

Jun 27, 2022 9:06:56 GMT -5 405x5 said:

Jun 25, 2022 19:39:11 GMT -5 Boomzilla said:

Probably need a “pro” amp to drive them…. Anyone heard them?

I’ve got THE amp. that could drive those loudspeakers with ease. (Signature 400).
But would I??
I would not speculate without giving them a fair listen, but that driver array layout is in conflict with most of the guidance I trust from the engineers I’ve followed

I too have amps that can easily drive those loudspeakers with ease. (XPR-1’s) 😆🎶🎶🎶

[KeithL]

I'm afraid that  you are not correct... or at least not entirely.

A loudspeaker is essentially a motor.

The force that causes the cone to move works this way:
The current in the voice coil creates a magnetic field.
The magnetic field in the voice coil pushes against the magnetic field from the permanent magnet.
And the voice coil pushes the cone which is attached to it.
At the same time the suspension and the spider act as springs trying to keep the cone right where it is.
In the classical model the cone is a weight hanging from a spring - and the voice coil pushes the weight up and down.
NOTE HOW, IF YOU PUSH THE WEIGHT UP OR DOWN, IT WILL THEN CONTINUE TO BOUNCE UP AND DOWN.

To fill in a few pieces....
The "sound waves" you hear are the movement of the air the weight pushes out of the way as it moves up and down.
In a sealed cabinet the air in the cabinet counts as part of the spring - along with the spider and surround.
In a ported cabinet the air in the port counts as part of the weight - and also a little bit as part of the spring.

In percentages, only a few percent of the energy you feed in goes to push air out of the way of the weight (sound).
(This is "efficiency" - and, for a sealed speaker, this is usually between 1% and 2%.)
There are other "losses" that dissipate some of this energy....
What we call mechanical damping is actually mechanical friction between the molecules inside the flexible surround and spider...
And the stuffing in the cabinet acts to burn up energy via air friction as the air moves around...
All of the rest goes to keep the weight bouncing up and down.

Tap the cone of a speaker that is NOT connected to an amplifier and it makes a hollow drawn out thump...
That's the sound of the cone bouncing back and forth, for a relatively long time, until it uses up the energy from being struck.
Now connect that speaker to an amplifier that's turned on and tap it...
All you'll hear is a single relatively sharp thump.

The reason is that, as well as being a "motor", a speaker is also a GENERATOR.
When the voice coil moves in the magnetic field it acts as a generator.
(The technical term is to say that "it generates back EMF" - back electromotive force".)
When the output of the amplifier is zero it acts to "short out the back EMF from the speaker".
(And, when you do that, "the generator tends to come to a rapid halt".)
This is exactly the same way a "dynamic magnetic braking system" works.
(On New York subway trains the power generated by this braking force is dissipated by heating huge banks of heating coils.)
 
THE ABILITY OF THE AMPLIFIER TO APPLY BRAKING FORCE TO THE DRIVER IS ANOTHER TERM FOR "DAMPING FACTOR".
It is this ability that allows the amplifier to control the movement of the speaker.
This ability to dissipate back EMF is related to:
- the "damping factor", which is the RATIO of the impedance of the speaker and the amplifier
- the strength of the magnet and its magnetic field
- the characteristics of the voice coil
- the coupling between the magnet and the voice coil

THERE IS NO INHERENT BENEFIT OF A SPEAKER WITH A 2 OHM VOICE COIL OR AN AMPLIFIER RATED TO DRIVE A 2 OHM LOAD.

Here's how it works....
Assuming you take the exact same amplifier....
You connect that amplifier and connect it to an 8 Ohm speaker and measure its damping factor.
If you connect that same amplifier to a 4 Ohm speaker its damping factor will be HALF of what it was when connected to an 8 Ohm speaker.
If you connect that same amplifier to a 2 Ohm speaker its damping factor will be HALF AGAIN of what it was when connected to an 4 Ohm speaker.
So, in fact, for a given amplifier, the lower the impedance of the speaker, the LOWER the damping factor, and THE LESS ABLE the amplifier will be to control the speaker.

HOWEVER, if you have an amplifier that has a damping factor that is ADEQUATE to control a 2 Ohm speaker well...
Then it will have DOUBLE that damping factor when connected to a 4 Ohm speaker...
And QUADRUPLE that damping factor when connected to an 8 Ohm speaker...

Damping Factor is "the impedance of the speaker divided by the output impedance of the amplifier".
(And the output impedance of the amplifier is determined by its design and does not change.)

The reason so many speaker manufacturers sell 4 Ohm speakers today has NOTHING to do with this.
The reason is simply that most solid-state amplifiers deliver more power into 4 Ohms than they do into 8 Ohms.
And virtually all of them have a damping factor that is so high that they work well with either 4 Ohm or 8 Ohm speakers. 
So speaker manufacturers tend to design their speakers to get the most power from the amplifiers they are most likely to be connected to.

Note that there is also an economy of scale with driver manufacture... where a certain speaker driver costs less because more are manufactured or sold.
However, with modern home speaker crossovers, the impedance of the individual drivers does not specifically determine the overall impedance of the speaker anyway.
For example I could just as easily connect the same pair of 4 Ohm woofers in series to make 8 Ohms or in parallel to make 2 Ohms.
Likewise, in most cases, I can buy a virtually identical driver in "a 4 Ohm version or an 8 Ohm version" for a similar price.
 

Jun 26, 2022 20:33:57 GMT -5 Boomzilla said:

As I understand it, the greater the current through the woofer's voice coil, the tighter the control that the amplifier has on the load. And that, unless I'm mistaken, is why so many speaker makers these days sell 4-ohm speakers instead of the 8-ohm or 16-ohm models that were popular in earlier years. Class D amplifiers (that are rapidly coming into common usage) are more often capable of 2-ohm loads than other types. So 2-ohm capable amps + 2-ohm speakers at least theoretically offer tighter bass than speakers with less voice-coil current capability.

[KeithL]

I'll throw in a cool tip here...

Take your speaker and entirely disconnect the speaker wires...
Tap the cone of the woofer gently...
Listen to the sound...
(At this point you have "a damping factor of 0".)

Now connect a short length of wire directly across the woofer terminals - shorting them.
Tap the cone of the woofer gently...

Listen to the sound...

(At this point you have "a VERY HIGH damping factor".)

Odds are, with the wire connected, if you have modern speakers, you'll hear a much "sharper" and "cleaner" thump.
If you hear a major difference between those two then your speaker will probably sound better if you use an amp with a high damping factor.
If you hear very little difference then, with your speaker, damping factor probably is not very critical.

(This test is really significant with a separate driver... but may or may not tell you much with a complete speaker.)

NOTE, however, that damping factor doesn't matter much above about 100.
So, for a tube amp, whose DF normally ranges between 4 and 8, DF really matters.
But, for a solid state amp, it really doesn't matter whether the DF is 100, or 500, or 1000.
(In fact the number is pretty meaningless above about 500 - which is why we simply say "over 500".) 

Jun 27, 2022 11:19:50 GMT -5 KeithL said:

I'm afraid that  you are not correct... or at least not entirely.

A loudspeaker is essentially a motor.

The force that causes the cone to move works this way:
The current in the voice coil creates a magnetic field.
The magnetic field in the voice coil pushes against the magnetic field from the permanent magnet.
And the voice coil pushes the cone which is attached to it.
At the same time the suspension and the spider act as springs trying to keep the cone right where it is.
In the classical model the cone is a weight hanging from a spring - and the voice coil pushes the weight up and down.
NOTE HOW, IF YOU PUSH THE WEIGHT UP OR DOWN, IT WILL THEN CONTINUE TO BOUNCE UP AND DOWN.

To fill in a few pieces....
The "sound waves" you hear are the movement of the air the weight pushes out of the way as it moves up and down.
In a sealed cabinet the air in the cabinet counts as part of the spring - along with the spider and surround.
In a ported cabinet the air in the port counts as part of the weight - and also a little bit as part of the spring.

In percentages, only a few percent of the energy you feed in goes to push air out of the way of the weight (sound).
(This is "efficiency" - and, for a sealed speaker, this is usually between 1% and 2%.)
There are other "losses" that dissipate some of this energy....
What we call mechanical damping is actually mechanical friction between the molecules inside the flexible surround and spider...
And the stuffing in the cabinet acts to burn up energy via air friction as the air moves around...
All of the rest goes to keep the weight bouncing up and down.

Tap the cone of a speaker that is NOT connected to an amplifier and it makes a hollow drawn out thump...
That's the sound of the cone bouncing back and forth, for a relatively long time, until it uses up the energy from being struck.
Now connect that speaker to an amplifier that's turned on and tap it...
All you'll hear is a single relatively sharp thump.

The reason is that, as well as being a "motor", a speaker is also a GENERATOR.
When the voice coil moves in the magnetic field it acts as a generator.
(The technical term is to say that "it generates back EMF" - back electromotive force".)
When the output of the amplifier is zero it acts to "short out the back EMF from the speaker".
(And, when you do that, "the generator tends to come to a rapid halt".)
This is exactly the same way a "dynamic magnetic braking system" works.
(On New York subway trains the power generated by this braking force is dissipated by heating huge banks of heating coils.)
 
THE ABILITY OF THE AMPLIFIER TO APPLY BRAKING FORCE TO THE DRIVER IS ANOTHER TERM FOR "DAMPING FACTOR".
It is this ability that allows the amplifier to control the movement of the speaker.
This ability to dissipate back EMF is related to:
- the "damping factor", which is the RATIO of the impedance of the speaker and the amplifier
- the strength of the magnet and its magnetic field
- the characteristics of the voice coil
- the coupling between the magnet and the voice coil

THERE IS NO INHERENT BENEFIT OF A SPEAKER WITH A 2 OHM VOICE COIL OR AN AMPLIFIER RATED TO DRIVE A 2 OHM LOAD.

Here's how it works....
Assuming you take the exact same amplifier....
You connect that amplifier and connect it to an 8 Ohm speaker and measure its damping factor.
If you connect that same amplifier to a 4 Ohm speaker its damping factor will be HALF of what it was when connected to an 8 Ohm speaker.
If you connect that same amplifier to a 2 Ohm speaker its damping factor will be HALF AGAIN of what it was when connected to an 4 Ohm speaker.
So, in fact, for a given amplifier, the lower the impedance of the speaker, the LOWER the damping factor, and THE LESS ABLE the amplifier will be to control the speaker.

HOWEVER, if you have an amplifier that has a damping factor that is ADEQUATE to control a 2 Ohm speaker well...
Then it will have DOUBLE that damping factor when connected to a 4 Ohm speaker...
And QUADRUPLE that damping factor when connected to an 8 Ohm speaker...

Damping Factor is "the impedance of the speaker divided by the output impedance of the amplifier".
(And the output impedance of the amplifier is determined by its design and does not change.)

The reason so many speaker manufacturers sell 4 Ohm speakers today has NOTHING to do with this.
The reason is simply that most solid-state amplifiers deliver more power into 4 Ohms than they do into 8 Ohms.
And virtually all of them have a damping factor that is so high that they work well with either 4 Ohm or 8 Ohm speakers. 
So speaker manufacturers tend to design their speakers to get the most power from the amplifiers they are most likely to be connected to.

Note that there is also an economy of scale with driver manufacture... where a certain speaker driver costs less because more are manufactured or sold.
However, with modern home speaker crossovers, the impedance of the individual drivers does not specifically determine the overall impedance of the speaker anyway.
For example I could just as easily connect the same pair of 4 Ohm woofers in series to make 8 Ohms or in parallel to make 2 Ohms.
Likewise, in most cases, I can buy a virtually identical driver in "a 4 Ohm version or an 8 Ohm version" for a similar price.
 

Jun 26, 2022 20:33:57 GMT -5 Boomzilla said:

As I understand it, the greater the current through the woofer's voice coil, the tighter the control that the amplifier has on the load. And that, unless I'm mistaken, is why so many speaker makers these days sell 4-ohm speakers instead of the 8-ohm or 16-ohm models that were popular in earlier years. Class D amplifiers (that are rapidly coming into common usage) are more often capable of 2-ohm loads than other types. So 2-ohm capable amps + 2-ohm speakers at least theoretically offer tighter bass than speakers with less voice-coil current capability.

[Boomzilla]

From: www.h2wtech.com/category/voice-coil-actuators?gclid=CjwKCAjwquWVBhBrEiwAt1KmwtW1do0gy7CkvsTUk8pgC-472fsOAkDeu3LoDrTcsOJ5FtCownuGTxoCA-AQAvD_BwE#productInfo1

"Voice coil motors operate on the principal of the Lorentz force equation:

Force = B × I where B = Flux density (Tesla) & I = Current (Amps)

Simply stated, a current carrying conductor placed in a magnetic field will have a force exerted upon it. This force is proportional to the direction and magnitude of the current and the flux density field. Since the permanent magnet flux density field is fixed, the direction of the linear displacement depends on the polarity of input current. The amount of force that is produced is directly proportional to the magnitude of the input current."

Is not the current greater in a 2-ohm voice coil than in one of greater impedance?

[KeithL]

Absolutely.... and all of that describes the force the amplifier uses to make the speaker move.

HOWEVER....

Once the speaker cone is moving is has momentum just like any other mass.
So, in essence, you have a moving mass, attached to a spring, bouncing back and forth.
And, while the amplifier may exert another force to move the speaker in the other direction, it does not exert a force to STOP the speaker from moving.

So, for example, let's say you send a single cycle of a sine wave to the speaker.
The amplifier "pushes" the speaker in one direction...
Then it pushes it back in the other direction...
But, once the speaker returns to its resting spot from that second push, there is no signal, so the amplifier "simply lets go"...
It is NOT exerting a force to STOP the speaker cone.
And, at that point, the speaker will simply bounce back and forth on its spring until all of the remaining energy dissipates.
This is what we call "sloppy bass".
The energy will eventually be used up making sound, or in other forms of damping, but the speaker may continue to move for several cycles.
(In that regard the speaker is just like a bell - only it "rings" at a relatively low frequency.)

This is where Damping Factor comes in.

Once the amplifier is no longer pushing the speaker like a motor...
The speaker can be considered to be a coil in a magnetic field - a generator.
And, at this point, when the signal is zero, we want the amplifier to apply braking force to get the speaker to stop.

If the amplifier had a damping factor of zero this would be equivalent to disconnecting it at that point.
The "generator effect" would be largely meaningless since there would be no path for current flow.

However, with a damping factor of greater than zero, the current from this "generator" can flow back through the amplifier.
This, in turn, "puts a load on the generator", allowing the momentum stored in the speaker to "be used up powering the generator".
This is simply another way of describing "magnetic braking force".
And it will stop the speaker cone much more quickly.

The HIGHER the Damping Factor, the LOWER the impedance of the amplifier when viewed this way, and the more braking force it can apply.
So the speaker stops bouncing around more quickly, stops making sound more quickly, and "the bass sounds tighter and cleaner".
Many older speakers have lots of internal damping (OTHER forces like friction that burn up this energy).
Most modern speakers, with powerful magnets and heavy cones, do not.
(And this will determine how much difference the braking provided by the amplifier will make in how that speaker sounds.)

You've also omitted a very important part of that equation... 
That equation describes the force on a single piece of wire with current flowing through it...
The "current" in that equation is TOTAL current...
When you have a coil you must MULTIPLY the current by the number of windings...
So..... 
The amount of flux generated by 1 amp of current going through 10 windings on a 2 Ohm voice coil...
Is the same as the amount of flux generated by 1/2 amp of current going through 20 windings on a 4 Ohm voice coil...
And, all else being equal, that 2 Ohm voice coil will have less turns, but of heavier wire, and so will weigh about the same.
(And, if you try to double the current, without making the wire thicker, then it will get hot quicker, have higher thermal losses, and be easier to overheat.)

And, yes, there are lots of other factors involved.
Like the fact that the losses in your speaker wire will be higher...
And that, unless several design changes are made, the losses in the amplifier's output stage will be MUCH higher.
(And remember that all of this applies to "driving force" but not "braking force".)

Jun 27, 2022 13:18:21 GMT -5 Boomzilla said:

From: www.h2wtech.com/category/voice-coil-actuators?gclid=CjwKCAjwquWVBhBrEiwAt1KmwtW1do0gy7CkvsTUk8pgC-472fsOAkDeu3LoDrTcsOJ5FtCownuGTxoCA-AQAvD_BwE#productInfo1

"Voice coil motors operate on the principal of the Lorentz force equation:

Force = B × I where B = Flux density (Tesla) & I = Current (Amps)

Simply stated, a current carrying conductor placed in a magnetic field will have a force exerted upon it. This force is proportional to the direction and magnitude of the current and the flux density field. Since the permanent magnet flux density field is fixed, the direction of the linear displacement depends on the polarity of input current. The amount of force that is produced is directly proportional to the magnitude of the input current."

Is not the current greater in a 2-ohm voice coil than in one of greater impedance?

[Boomzilla]

I'm missing something here, KeithL - If damping factor rather than current is the most critical aspect of cone control, then why don't manufacturers make 100-Ohm speakers? Certainly that would increase damping factor by a huge amount and even the wimpiest AVR could drive them like a Krell.

[DavidR]

I think the answer is a 100 ohm speaker would not sound good.

The lower the impedance, the more efficiently it allows the electric signal, which is basically the music, to pass through the speaker.

There is a thread on the Classic Speaker Pages that explains how/why AR would chose to make a speaker 4 or 8 ohms. I will see if I can find it but the search engine sucks and if the thread has been archived it will usually not come up using the search function. IIRC it had a lot to do with how they wanted the speaker to sound.

[KeithL]

It may sort of seem that way... but in fact it is far more complicated... for a bunch of reasons.

There are also all sorts of other issues regarding controlling a cone...
Like the strength of the motor...
And the strength, and weight, and stiffness of the cone...
It doesn't help to have a perfect motor if the cone is going to flex, or ring like a bell, or shatter into a million pieces.
And who says a cone is even the best choice?
Part of the basic problem with cones is that you're using a lot of force to wave a heavy cone back and forth to move a relatively tiny mass of air.
(In technical terms: "Really AWFUL impedance matching between the cone and the air.")

There were in fact speakers with impedances that high... several hundred Ohms... back in the very early days of tube amplifiers.
(You'll probably even find one or two on eBay if you want to play with one.)
If the impedance of the speaker is high enough then you don't need an output transformer to match the plate impedance of the tubes to the speaker.
There were actually speakers that just ran the plate of the tube directly through the voice coil.
(They were so stiff the DC offset just didn't matter.)
And, back when permanent magnets were pretty poor, as well as expensive, there were speakers that had electromagnets.
(And a few designs were really creative and used the electromagnet on the speaker as an inductor in the DC plate supply for the tubes.)
There were also table radios that had a crude little electrostatic tweeter connected directly to the plate of the output tube.
There was a lot of interesting weird stuff back in those days.

However... as for 100 Ohm speakers...

1.
They wouldn't work very well with modern amplifiers.
Your amplifier that is 200 watts into 4 Ohms and 100 watts into 8 Ohms would only deliver six or seven watts into 100 Ohms. 
So you'd need a special amplifier designed to work effectively at such a high impedance.

2.
The impedance of the speaker's voice coil is directly related to the number of turns of wire used.
A 100 Ohms voice coil requires a LOT more turns than a 4 Ohm or 8 Ohm voice coil.
So, unless you want it to be incredibly heavy, you have to use VERY thin wire.
And very thin wire has much higher resistance (and is also easier to burn out if you overcurrent it).

3.
The crossover will also operate at a higher impedance...
So, smaller capacitors, running at higher voltages (nice film capacitors)...
And coils with higher inductance (big coils with lots of turns of really thin wire)...

4.
When you're talking about damping factor you start by assuming that the speaker is "a perfect generator".
The voice coil in the magnetic field is the "generator"...
And damping occurs because you are able to "short out the current produced by the generator"...
(It is this current flow that generates the magnetic field that opposes the motion of the voice coil.)
And, "looking back into the output of an amplifier with plenty of feedback", you "see" a VERY low DC impedance.
HOWEVER, if you "model it out", the DC resistance of the speaker wire, and the speaker's voice coil, is in series with that impedance.
So, on one side of the ratio that determines the Damping Factor, you have the "source impedance" of the loudspeaker...
But, ON THE OTHER SIDE of that ratio, you have the output impedance of the amplifier PLUS the DC resistance of the voice coil, the speaker wire, and the crossover.
(Those are all resistances that tend to limit the amount of current than will flow through the circuit.)
Those combined DC resistances set a sort of limit on the overall effective damping factor.

5.
There are also other factors that limit the overall level of damping available.
Things like the degree of coupling between the magnetic fields and the relative "stiffness" of each.
The fields are not perfectly coupled together and neither are they infinitely powerful.

6.
Also remember that there is no specific goal "to have infinite damping".
In practice it is much more important that the design choices be BALANCED.
Vintage speakers tend to sound "dry" on modern amps - because they are designed to sound correct with tube amps that have low damping.
They are designed NOT to be controlled too tightly and this lack of tight control has been accounted for in their design parameters.
Therefore they often sound "over-controlled" when connected to a modern amplifier that has more damping than they were designed to go with.
Most modern loudspeakers are the opposite...
They sound "sloppy and inadequately controlled" when paired with an amplifier with a too-low damping factor.
Because they're designed to be used with amplifiers with much higher damping factors that provide "firm control".
But they still reach their point of diminishing returns with a DF of around 100 or so...
(You're not going to stop a heavy cone instantly, no matter how powerful your motor is, and a heavier cone, more able to withstand the stress, will in turn end up being heavier.)

COULD you design a new loudspeaker with a 100 Ohm voice coil that worked well when paired with an appropriately designed amplifier?
Quite probably.

But I suspect that the tradeoffs would not be worth the gains.
The current values were arrived at because they are the best compromise that anyone has been able to figure out between the various tradeoffs.
And they now have the added benefit of being standardized and well understood.

And remember that your wimpy 50 wpc AVR might indeed be able to drive your 100 Ohm speaker "like a Krell"...
Right up to the one or two watts that it was able to deliver into a 100 Ohm load.
(So, assuming that the circuitry was otherwise well designed, which is probably not a good assumption, a really small Krell.)
(I really somewhat mis-phrased that... since your 100 wpc into 8 Ohm Krell will also be limited to two or three watts into a 100 Ohm speaker.) 
(And bearing in mind that the speakers themselves might or might not sound good... for other reasons.)

Jun 27, 2022 16:47:13 GMT -5 Boomzilla said:

I'm missing something here, KeithL - If damping factor rather than current is the most critical aspect of cone control, then why don't manufacturers make 100-Ohm speakers? Certainly that would increase damping factor by a huge amount and even the wimpiest AVR could drive them like a Krell.