Constant Power

Roger Dressler

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If anyone knows, I'm curious:

>>Power Paradigm is the method of design, test and measurement<<
>>Crossover design rules<<

When did the term "Power Paradigm" first enter the lexicon by name? Where are the methods for test and measurement codified? Where are the crossover design rules described?

When were the characteristics of power paradigm amps first described as a preferred way to drive loudspeakers compared with voltage paradigm amps?

What output impedance range defines a power paradigm amp? >>1-20 ohms is typical<< What is the ideal impedance? Is it flat over the audible frequency range? If not, is there an ideal characteristic?

Is high 2nd-order distortion (e.g. 10%) merely inconsequential, or is it a positive attribute in the rendering of sound? If it is positive, is it desirable to have more than 10%? Is there an optimal value? How much is too much? What about other even-order harmonics? What is the ideal relationship of these to the 2nd harmonic? Falling? Falling fast? None?

If a 30w Power Paradigm amp makes 5% 2nd harmonic distortion at 10w, what would it ideally be at 20w? Same? More? Less? Doesn't matter? Is there an optimum slope to the curve or relationship between 2nd harmonic and power output defined in the Power Paradigm school?

What level of 3d, 5th and higher odd harmonics exist in Power Paradigm amps and in SOTA Voltage Paradigm amps?

Thanks!
 

Phelonious Ponk

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If anyone knows, I'm curious:

>>Power Paradigm is the method of design, test and measurement<<
>>Crossover design rules<<

When did the term "Power Paradigm" first enter the lexicon by name? Where are the methods for test and measurement codified? Where are the crossover design rules described?

When were the characteristics of power paradigm amps first described as a preferred way to drive loudspeakers compared with voltage paradigm amps?

What output impedance range defines a power paradigm amp? >>1-20 ohms is typical<< What is the ideal impedance? Is it flat over the audible frequency range? If not, is there an ideal characteristic?

Is high 2nd-order distortion (e.g. 10%) merely inconsequential, or is it a positive attribute in the rendering of sound? If it is positive, is it desirable to have more than 10%? Is there an optimal value? How much is too much? What about other even-order harmonics? What is the ideal relationship of these to the 2nd harmonic? Falling? Falling fast? None?

If a 30w Power Paradigm amp makes 5% 2nd harmonic distortion at 10w, what would it ideally be at 20w? Same? More? Less? Doesn't matter? Is there an optimum slope to the curve or relationship between 2nd harmonic and power output defined in the Power Paradigm school?

What level of 3d, 5th and higher odd harmonics exist in Power Paradigm amps and in SOTA Voltage Paradigm amps?

Thanks!

Excellent questions. Another: Are voltage paradigm and power paradigm clearly defined engineering terms that are broadly accepted and applied, or are they more proprietary language? I ask because a Google search turns up little, and leads straight to Atmasphere. Perhaps these are terms of your own creation?

Tim
 

Duke LeJeune

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Where are the crossover design rules described?

Since I'm a speaker designer instead of an amplifier designer, I'll just respond to my area.

Designing a crossover for a power paradigm amp is no big deal (well, no bigger deal than crossover design in general). If you have such an amp on hand, you can use that amp to make your measurements and conduct your listening tests. If not, then keep the impedance curve fairly high and as smooth as you reasonably can, and take the anticipated amplifier/speaker interaction into account where you can't.

We are simply more accustomed to the idiosyncrasies of voltage-source amplifiers, which deliver increased wattage into an impedance dip and decreased wattage into an impedance peak. That is no more intrinsically correct than delivering constant power into the load, or even going to the other extreme and behaving as a current source and delivering increased wattage into an impedance peak and decreased wattage into an impedance dip.
 

mep

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MEP, you missed some things and made some incorrect assumptions in your opening post.

Really? Exactly what did I miss and what incorrect assumptions did I make? You basically rehashed everything you already said.

So I will try to clarify. Please refrain from Logical Fallacies as you have used in the past. I want to keep this as an intelligent debate. If you do not understand what Logical Fallacies are (such as the Strawman), please google the phrase.

I have to be honest and tell you that I’m very tired of you accusing me of “logical fallacies” and “strawman arguments.” I’ve already pointed out several times how you changed my words in a previous statement I made so you could turn around and accuse me of a strawman argument when there was none until you created a reverse strawman argument. And if you haven’t figured out by now that I did read and understand your paper and that it would have probably been a better choice not to be so condescending in your tone and remarks that we might actually have a more desirable conversation.

In short a Power Paradigm loudspeaker is any loudspeaker that can be driven with reasonably flat frequency response by an amplifier of moderate output impedance (1-20 ohms is typical; impedances above that we shall call 'high impedance', as there is also a current-drive method which has been mentioned by Nelson Pass but remains mostly a DIY matter; such amplifiers may have an output impedance as high as 80 ohms), wherein the amplifier has little or no negative feedback. There may be several means of obtaining flat frequency response; examples are port tuning (ex.: Audiokinesis) and midrange/tweeter level controls.

Ralph-Please tell us if there are any tube amplifiers with output transformers on the market with an output impedance of 5 ohms or greater. If you want to call an amplifier with an output impedance of 10-20 ohms moderate, do you mean moderate for an OTL? And even though I know you said 1-20 ohms would be considered moderate, I picked the higher end of your band and just left 10-20 ohms because that wouldn’t be considered a moderate output for a tube amp with output transformers nor is it common to all OTL amps either. Both the Graaf GM200 and the Transcendent Audio T8 OTL amps to list two examples have an output impedance of under 1 ohm.

There are several points to keep in mind:
#1 If you mix technologies you will get a frequency response error. That is to say that a Voltage Paradigm amplifier (one that is capable, IOW, of constant voltage response with respect to load impedance) will have a frequency response error when driving a Power Paradigm loudspeaker and vice versa. This can be because the crossover design rules for a Power Paradigm loudspeaker are different. The result can be that the drivers in the speaker (in the case of a dynamic loudspeaker) may be trying to reproduce material outside of their passband because the crossover does not work correctly with the amplifier (this is why many older horns have a reputation for being 'honky').

What speaker company advertises their speakers as “power paradigm” speakers and who advertises their speakers as “voltage paradigm” speakers? What high-end magazine or audio journal classifies speakers in this manner? Are there any? From time to time you will see measurements of a speaker by JA in SP and he will warn people the speaker under test will best be driven by a SS amp due to the demands it will place on a power amplifier. I think if speakers were strictly designed and built to be “power paradigm” speakers or “voltage paradigm” speakers, they would be advertised and sold that way and we would see special categories in TAS, Stereophile, and other magazines in their recommended component special issues for speakers in these categories.

SP ranks their speakers according to Class A, Class A limited low frequency, Class B, and Class C. Unless I missed it, there is no breakout for “power paradigm” speakers and “voltage paradigm” speakers. The only information/recommendation I see coming from the majority of speaker companies regarding amplifier choice are the standard efficiency, nominal impedance, minimum recommended power, and maximum recommended power.

If speaker companies truly designed and built their speakers to only be used by “power paradigm” amplifiers or “voltage paradigm” amplifiers, don’t you think they would tell us that? I think the real truth is that most speakers can be happily driven by either SS or tube amps with output transformers, but the number of speakers that can be driven by an OTL amp with an output impedance of 10 ohms or greater with high fidelity will be a much smaller subset of speakers that can be driven very well (meaning with high fidelity) by either a SS amp or a tube amp with output transformers.

#3 to obtain flat frequency response with a Power Paradigm amplifier you do not need a speaker with a flat impedance curve (although they can work just fine with that, and as a result, there is some cross over between camps). To get flat bandwidth, the overall impedance of the speaker has to be either a) high enough overall or b) designed to expect a certain behavior out of the amp if the impedance is lower. An example of this is the Wilson Watt/Puppy, which has a 2 ohm impedance at 2KHz because of a 2KHz trap which is intended to kill excess energy. This works great with amps that have a higher output impedance such as a tube amplifier, but not so great with a SS amp. The result is that the Watt/Puppy had a reputation for being bright (see #1 above). However it had no such brightness if used with the equipment for which it was designed.

First of all, I don’t know how a speaker could be “designed to expect a certain behavior out of the amp if the impedance is lower.” Unless the speaker company specifically recommends an amplifier for use with their speaker, how would they possibly know what to expect from all of the possible amplifier choices? With regards to the Wilson example you have used repeatedly, Wilson Audio does not market their speakers as power paradigm speakers that should be driven by tube amplifiers. Wilson provides some adjustments you can make to their speakers in order to accommodate SS or tube amplifiers.


#4 The Voltage Paradigm was developed in the late 1950s and into the early 1970s. Electro-Voice and Macintosh were leaders in setting up the technique, with the goal being predictable flat frequency response.

Do you have any papers you could reference with regards to McIntosh being leaders in the voltage paradigm? Since both McIntosh tube amps and all but their cheapest SS amps use output transformers, that puts them in the “power paradigm” camp and not the “voltage paradigm” camp. And it would only follow that if McIntosh amps were designed following the rules of the “power paradigm” that their speakers would be designed the same way.

If you want to avoid that you have to avoid negative feedback in the amplifier. This means that you have to find other ways to obtain linearity in the amplifier, and other ways to get flat frequency response in the loudspeaker. Enter the Power Paradigm. It is a lot easier to build an amplifier with good linearity with no feedback if you use tubes. So quite often tube amplifiers operate with little or no feedback. This results in a higher output impedance which must be dealt with differently and properly in the loudspeaker crossover and box (if there is a box) design.

I think it would be a more accurate statement to say that quite often SE triode tube amplifiers operate with little or no feedback. It’s far less common to see push-pull tube amps use zero feedback than it is to see SE amps using zero feedback.
 

mep

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Excellent questions. Another: Are voltage paradigm and power paradigm clearly defined engineering terms that are broadly accepted and applied, or are they more proprietary language? I ask because a Google search turns up little, and leads straight to Atmasphere. Perhaps these are terms of your own creation?

Tim

The terms current source and voltage source have been around for a long time. The terms voltage paradigm and power paradigm may have been created when Ralph wrote his paper which is why I originally asked him if the paper had been reviewed by his peers which led to another food fight of logical fallacy/strawman bogus arguments.
 
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andy_c

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mep

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Bob Cordell, who wrote a book on power amplifier design and has been a peer reviewer for the AES in the past (not sure if he is still doing that now), has commented on the so-called power paradigm.

He commented on it all right. Apparently right back to Ralph and he didn't agree with him. Here is the post you linked to and it is very interesting to say the least:

Posted by Bob Cordell (A) on September 12, 2006 at 13:27:16

In Reply to: Re: didn't mean that at all- posted by Ralph on September 12, 2006 at 10:10:03:

Ralph,
Thanks for your interest in the workshops we will be holding. I think a couple of them will be relevant to your question. First, we will be doing measurements on amplifiers and in so doing will discuss and speculate on how measurements do or do not correlate to the sound. In the amplifier listening workshop, we will compare the sound of a vacuum tube amplifier with that of a solid state amplifier; because the output impedance of the vacuum tube amplifier is a bit higher, one could argue that it falls closer to what you describe as the constant power paradigm. Finally, we will provide a demonstration of the average and peak power (referred to 8 ohms) levels on well-recorded music playing into a given loudspeaker. Our plan is to display rms average and peak value of average power simultaneously on digital readouts calibrated in watts average power into 8 ohms. This is intended to illustrate the crest factor of the program, and by extension the likelihood of whether one's amplifier is clipping.

Now to the specifics of your question. I have to say that I don't subscribe to so-called constant voltage and constant-power paradigms as you described them. The constant power paradigm is particularly problematic, since with most loudspeakers, if you deliver a truly constant power to the device, its frequency response will be very far from flat. Indeed, if you look at the impedance curve, you will see for many speakers a large rise, sometimes to tens of ohms, at the bass resonant frequency and again at the crossover frequency. Such impedance rises suggest that the true power efficiecy of the loudspeaker is significantly increased at these frequencies. Feeding constant power to the loudspeaker at these frequencies would result in both a voltage rise at the terminals and an SPL rise at the acoustic output. The bottom line is that most speakers are designed for, and voiced for, a constant voltage input (regardless of the power that that happens to correspond to).

I know of no audio power amplifier that produces constant power into a widely varying frequency-dependent speaker input impedance. You may get a little closer to that with an amplifier with a higher output impedance, but still not a lot closer. Closer enough to alter the sound, however. Even the constant current amplifiers that some have proposed are not constant power.

I also don't see stereotyping so-called subjectivistis and objectivists into constant power and constant voltage camps, respectively. This would be similar to categorizing bottleheads as all subjectivists and solid state afficiandos as all objectivists - something that seems wrong to me.

I hope I have addressed your question, and hope you can join us at RMAF for our workshops.

B
 

microstrip

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Mep,

I am sure that many people will not agree with Ralph Karsteen and I am not worried at all with it.
He presented an explanation for something that we perceive in many amplifiers and speakers. I have often experienced it. It has some logic that goes against the mainstream of current design, and as most speakers are a mix of power and voltage paradigm can not be easily demonstrated.

However we have many reasons to consider that the voltage paradigm is not perfect - just consider that some of the solid state power amplifiers that are highly praised in this forum by audiophiles have low damping factors, with output impedances around one third of the ohm. Aren't you worried about them?
 

Phelonious Ponk

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The terms current source and voltage source have been around for a long time. The terms voltage paradigm and power paradigm may have been created when Ralph wrote his paper which is why I originally asked him if the paper had been reviewed by his peers which led to another food fight of logical fallacy/strawman bogus arguments.

Yeah, I get that, and I'm no engineer but this seems to be attempting to describe something very different...a type of amplifier?

Tim
 

FrantzM

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Mep,

I am sure that many people will not agree with Ralph Karsteen and I am not worried at all with it.
He presented an explanation for something that we perceive in many amplifiers and speakers. I have often experienced it. It has some logic that goes against the mainstream of current design, and as most speakers are a mix of power and voltage paradigm can not be easily demonstrated.

However we have many reasons to consider that the voltage paradigm is not perfect - just consider that some of the solid state power amplifiers that are highly praised in this forum by audiophiles have low damping factors, with output impedances around one third of the ohm. Aren't you worried about them?

No one said that Voltage Paradigm is perfect either...

The point remains that the Power Paradigm is not clear to me unless we get to a point derided by most: Active speakers with amplifiers built for the purpose. The crossover can then be Active or passive and the amplifier tailored for the load. Else ...
IMHO Ralph fails to sustain his position clearly, he starts by accusing mep of argumentation fallacy without substantiating his points, another form of .. argumentation fallacy this one called: " Ad hominem".
I don't subscribe to this Power Paradigm notion I will address Ralph's reply in another post for now. Working on closing out a project...
The Power Paradigm is not new even in the WBF. Please read this post carefully
READ THIS
 

microstrip

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Yeah, I get that, and I'm no engineer but this seems to be attempting to describe something very different...a type of amplifier?

Tim

Tim,

Not at all. You can transfer electrical signals using voltage, current or power. For effective voltage transfer impedance of the source should be much smaller than that of the receiving unit, for current transfer the opposite, and for power transfer you should have similar impedance in both.

All these terms we are debating come primarily from the rules associated with these ratios. For example , people using antena's always think about the power paradigm.

Cordell main divergence with Ralph is on semantics and also mainly because he does not acknowledge the model of speaker that Ralph suggests, as he only considers the speakers that sound better (are voiced, as he says) for a constant voltage input.
 

microstrip

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(...) The point remains that the Power Paradigm is not clear to me unless we get to a point derided by most: Active speakers with amplifiers built for the purpose. The crossover can then be Active or passive and the amplifier tailored for the load. (...)

:confused: Active speakers with passive crossovers and tailored amplifiers? :confused: I am not following you!
 

andy_c

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Just for kicks, I did a simulation of a subwoofer designed to have flat response when driven from a low output impedance. It is a Dayton RSS390HF-4 in a 5.5 cubic foot box. Here is the impedance vs. frequency from 20 Hz to 200 Hz.



And here is the frequency response for 21 different source impedances - from 0 to 20 Ohms in 1 Ohm steps. The flattest response is for 0 Ohms.



You can easily see the phenomenon that Bob Cordell was talking about in the post of his I referenced. That is, at the frequency for which the speaker impedance is large, there is substantial frequency response peaking caused by the high output impedance.
 

Roger Dressler

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Aug 4, 2011
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Since I'm a speaker designer instead of an amplifier designer, I'll just respond to my area.

Designing a crossover for a power paradigm amp is no big deal (well, no bigger deal than crossover design in general). If you have such an amp on hand, you can use that amp to make your measurements and conduct your listening tests.
If one "Power Paradigm" amp's source impedance is 20 ohms and another is 1 ohm, what can you as a designer rely on for consistency? OTOH, all Voltage Paradigm amps have very low output impedances, thus removing them from the equation as a variable in how the speaker will react, i.e. sound. If the Wilson Watt/Puppy needs a 2 kHz trap to tailor the sound, that is easily immunized from the low source impedance of a typical power amp. I'd be very surprised if Wilson failed to design it accordingly, because to rely on the soft and uncertain source impedance of a high impedance amp means the sonic result would be left to serendipity. That does not sound like Dave Wilson to me (a.k.a detail control freak).

We are simply more accustomed to the idiosyncrasies of voltage-source amplifiers, which deliver increased wattage into an impedance dip and decreased wattage into an impedance peak. That is no more intrinsically correct than delivering constant power into the load, or even going to the other extreme and behaving as a current source and delivering increased wattage into an impedance peak and decreased wattage into an impedance dip.
Having a wide range of load tolerance is not an idiosyncrasy in my book. Eliminating unpredictable and uncontrollable variables from a system is a good thing.
 

mep

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Apr 20, 2010
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Mep,

I am sure that many people will not agree with Ralph Karsteen and I am not worried at all with it.
He presented an explanation for something that we perceive in many amplifiers and speakers. I have often experienced it. It has some logic that goes against the mainstream of current design, and as most speakers are a mix of power and voltage paradigm can not be easily demonstrated.

However we have many reasons to consider that the voltage paradigm is not perfect - just consider that some of the solid state power amplifiers that are highly praised in this forum by audiophiles have low damping factors, with output impedances around one third of the ohm. Aren't you worried about them?

Nope, not one bit. The paradigms aren't my paradigms and I'm not in the business of making or selling amplifiers of any type. We all make decisions on what amplifiers we want to buy and I have been happy with both SS and tube amps.
 

mep

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Tim,

Not at all. You can transfer electrical signals using voltage, current or power. For effective voltage transfer impedance of the source should be much smaller than that of the receiving unit, for current transfer the opposite, and for power transfer you should have similar impedance in both.

All these terms we are debating come primarily from the rules associated with these ratios. For example , people using antena's always think about the power paradigm.

Cordell main divergence with Ralph is on semantics and also mainly because he does not acknowledge the model of speaker that Ralph suggests, as he only considers the speakers that sound better (are voiced, as he says) for a constant voltage input.


That wasn't my take away from what Cordell said to Ralph. I think it's much much deeper than semantics.
 

andy_c

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That wasn't my take away from what Cordell said to Ralph. I think it's much much deeper than semantics.

Exactly. One could summarize Cordell's argument as follows:

  1. If an amplifier actually did deliver constant power to a speaker regardless of impedance, the system frequency response would be severely affected.
  2. No such amplifiers exist anyway.
  3. An amplifier having a high output impedance is not even a good approximation to one that delivers constant power to a load of varying impedance.
 

FrantzM

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:confused: Active speakers with passive crossovers and tailored amplifiers? :confused: I am not following you!

Well.. The way I see it an active speaker is one with an attached amplifier or amplifiers. The crossover can be anything you want or am I wrong? The amplifier -crossover -driver can be tailored to be perfectly matched. A system approach if you will ...
 

FrantzM

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That wasn't my take away from what Cordell said to Ralph. I think it's much much deeper than semantics.

Same here and agree with Andy_c post #37
 

mep

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No one said that Voltage Paradigm is perfect either...

The point remains that the Power Paradigm is not clear to me unless we get to a point derided by most: Active speakers with amplifiers built for the purpose. The crossover can then be Active or passive and the amplifier tailored for the load. Else ...
IMHO Ralph fails to sustain his position clearly, he starts by accusing mep of argumentation fallacy without substantiating his points, another form of .. argumentation fallacy this one called: " Ad hominem".
I don't subscribe to this Power Paradigm notion I will address Ralph's reply in another post for now. Working on closing out a project...
The Power Paradigm is not new even in the WBF. Please read this post carefully
READ THIS

Frantz-I'm glad someone else here besides me sees what is really going on here with regards to Ralph making false claims against me because I don't agree with him. With regards to your link, I see that Mark Seaton called him out on his paper as well. It's basically a fluff piece that won't withstand scientific scrutiny IMO. I offered to pay Ralph $100 if he could get his article published as written in a scientific publication, but of course that was probably also a strawman argument or a fallacy argument as well.

The thing I find most ironic is that Ralph tries to convince people that "power paradigm" amplifiers are superior and yet his amplifiers (or at least the MA-1) aren't close to meeting the definition of a "power paradigm" amplifier because they don't put out the same power into 4, 8, or 16 ohms. The power increases as the impedance increases which is the reverse of "voltage paradigm" amplifiers and not the same as tube amps with output transformers which come the closest to Ralph's ideal of equal power from 4-16 ohms.
 
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