# Hornresp

#### stv

Paid Member
just 30Watts of radiation we get 132dB, which we get from single source also, but radiating 60Watts of acoustical power.
Could there be an overseen change of radiation soundfield? 2pi and 4pi?

#### Crashpc

No. I posted the printsceens in here.

//Also here:
In the case, given the math, roughly, 57Watts of acoustical power is 87Pa.
Half power though 28,5Watts of acoustical power is, 61,3Pa.
Two half powers, 2x28,5Watts, give 2x61,3Pa, Which is 122,6Pa .It is right in the square function of the math/pressure relation to power.
I don´t see a radiation area in the math though, so it deserves more thinking on what´s happening really to the lowest level a primate an conceive and retain. I know I am not just smart or stupid. I am BOTH
It looks like if acoustical power still is not "energy in the air".

Last edited:

#### maxolini

Welcome to the matrix

1 user

#### Crashpc

I'd chew through this in two minutes in the middle school. Now it takes DAYS. Wiser, but dumber. Hope it is not beginning of real diagnosis. Sport and nourishment needed.
IQ points galloping one by one away fast. Saving grace is I had a lot in the beginning.

#### simmer

Hi all,

New to hornresp, I am trying to use it to simulate a horn that I'm considering building off of free plans I found. It's a front-loaded horn with an offset driver.
As best I can tell, unfolded, it will look like the drawing attached below - There's a narrowing after the first two segments, then expands again with a change in flare rate). But that means that, since I have to use S2 to locate the driver's offset, I seem to lack one segment to fully model this - I would need 5 ?
I'd like to find out how best to model that horn accurately.

I've seen David's post here that states:
Four segments is normally the limit however a front loaded horn can have in effect five segments by specifying a throat adaptor [...]
Can I use this to still model my horn with an OD ? How should one specify a throat chamber to replace the missing segment here ?

Side not, is there an obvious reason I'm missing why there's a 4 segment limit ? How would one simulate one that's more complex ? I don't know, seems arbitrary to my uninitiated eye, I'm obsessing about this a little and it seems like I'm missing something super obvious, if someone wants to point it out my brain will be happy.

#### Attachments

• 20240829_002015.png
91.3 KB · Views: 42

#### David McBean

New to hornresp, I am trying to use it to simulate a horn that I'm considering building

The throat adaptor becomes a throat chamber port in an offset driver system.

It will be necessary to approximate the actual design if it is to be modelled in Hornresp.

Two suggested approximations are shown in the attachments.

#### Attachments

• Attach_1.png
15.7 KB · Views: 32
• Attach_2.png
14.5 KB · Views: 31
• Attach_3.png
15.8 KB · Views: 30
• Attach_4.png
13.8 KB · Views: 31
1 user

#### David McBean

One would thought that under word efficiency, the most important would be the meaning of input watts versus output decibels.

As previously explained in Post #15,016, "input watts versus output decibels" is by definition a measure of sensitivity, not efficiency.

Sensitivity can be readily calculated in Hornresp using the Maximum SPL tool with the driver input power set to 1 watt and all other inputs switched off.

The black trace in the chart below shows the result for the 30Hz test system and the grey trace shows the result for the 40Hz system. At 40Hz the 30Hz system has the slightly higher sensitivity (100.8435 dB versus 99.5557 dB).

Incidentally, at 40Hz the two outputs of the 40Hz system have a phase difference of 106 degrees and the two outputs of the 30Hz system have a phase difference of 14 degrees.

1 user

#### Crashpc

@David McBean

Mr. Mcbean, healthy disagreement, however it ends, even you settling as being right, is very welcome. The whys and hows about that are the important thing, and new knowledge revealing the usability or proper use of the acquired data is more important to me, than hating on the naming of things and righteousness about that. Your views are most welcome. In some sense and raw definition you are completely right, and I am happy for you standing your ground. That is one thing, and another thing is the usability of such state for speaker developments.

"input watts versus output decibels" is by definition a measure of sensitivity, not efficiency.
I don´t believe so. The term speaker sensitivity is defined by voltage. Indeed input power versus decibels is also a "power sensitivity".
The issue here is that the acoustical power here is not the usable output we are after. Acoustical pressure is. And to my knowledge, efficiency is the ratio of input power and usable/wanted output/performance. It doesn´t make sense to want anything else than acoustical pressure (except for other qualities, which do not belong to the efficiency performance bracket anyways). Why would we not want acoustical pressure or sound pressure level as the "denominator" of the efficiency? It is sincere question. We might learn here big time.

Sensitivity can be readily calculated in Hornresp using the Maximum SPL tool with the driver input power set to 1 watt and all other inputs switched off.
Yes you showed and helped me with this many times. Power sensitivity indeed can be displayed this way.

The black trace in the chart below shows the result for the 30Hz test system and the grey trace shows the result for the 40Hz system. At 40Hz the 30Hz system has the slightly higher sensitivity (100.8435 dB versus 99.5557 dB).
Indeed. It looks like nothing, does it? Well, I´d say, at the place, where 2000Watts of power is dissipated, 1,288dB is significant difference. More so, when the cone on the one system is moving and cooling, and on the less efficient/sensitive it doesn´t, which is not reflected very well in such plot, if ever. Also one design works where the port is working well within its limits, and the other (given the limited box volume) is in heavier port compression, losing some more performance.

One could argue that the opposite situation happens above 60Hz. No it doesn´t. not that much energy there and not that much power input either. And the lower tuned solution still enjoys more cooling by cone displacement.

As seen in the table, the 40Hz design only loses 3 pascals due to phase mismatch of the cone output. That is negligible in out search for the core issue.

The table. "Single source equivalent power conversion efficiency". THIS! How do we get to such number?
I´m glad you took your time to respond. "No and why/because" is what was wished for. Other people only reach for dismissal from the point of nonexistant authority with some added snark on top of the useless response.

Last edited:

#### b_force

I don´t believe so.

Efficiency is by definition and matter of fact a dimensionless number.
Simply defined by the ratio between the output power vs input power of a system when we talk about energy efficiency.

Since its by definition a dimensionless number, we can ONLY have units of the same type in that ratio by the rules of mathematics and physics.
We can calculate all kinds of other ratios, sensitivity is one of the examples, in that case the ratio won't be a dimensionless number anymore.

In general a more sensitive system doesn't always have to have an high efficiency as well.
If we take the simplified version for loudspeaker drivers, they are very closely related.

Point is, they are not the same thing.
Related is NOT the same thing as equal. (especially not in mathematics and physics)

Now I do agree that it's not always the most useful way of looking at the performance of a single system.
Sometimes one part of that system can be made super efficient, but to get there we need another system that has poor efficiency.
Meaning that the sum of both systems isn't that efficient.
Or if we consider a less simplified version, the high efficiency will only be a part of range of interest.
Much more so if we are gonna take 3D space (angles) into consideration etc etc.

In that case we sometimes want to come up with a different ratio.
But you can't just simply change the well established definitions of physics that way.

offtopic part:
Just an idea/brainstorm, but maybe just why people can get a little grumpy at times?
These things can be very easily found in all kinds of literature, simple and advanced.
So discussing if that is even true or not, is completely pointless I think, but can also really come across as (very) disrespectful.
Especially when talking to people who know a thing or two about the subject(s) in question.
It can really come across as completely dismissing people's many years of knowledge, devotion, expertise and skills.
Involving yourself in a discussion also means doing homework and checking your own ideas (as well as others) with proper resources and literature.

Put I 100% agree with you that dismissing people with authority, snarky comments and especially getting personal, is far from being professional at the same time.
No one should tolerate such behavior, it leads to a very unsafe and hostile environment.

It can be a difficult line to balance at times as well, considering difference in language, culture, upbringing and personality.
We are all human beings in the end.

Anyway, those are just some thoughts about that subject

I always highly encourage people to keep asking.
There is not such a thing as dump questions!
But just please consider both sides of the table.

1 user

#### Crashpc

@b_force

I don´t believe so.
That´s not the point.
Efficiency is by definition and matter of fact a dimensionless number.
Simply defined by the ratio between the output power vs input power of a system when we talk about energy efficiency.
We might not be talking about energy efficiency, as it is not the desired performance/output measure marker. If one side is, we might point to that, in a way of arguing that this is not desired measure of performance/efficiency. I can see though, that different view causes a nasty problem, because the desired efficiency marker basically "cannot" be expressed by ratio or percentage. Yet in the table posted by mr Mcbean, it was done somehow.

Example. We want to illuminate an area or object efficiently. I chose a light bulb, someone else choses a LED. The LED used is UV or IR.
It illuminates the area or the object more efficiently than a lightbulb, but as we speak of illumination as light, I.E.: visible spectrum of electromagnetic wave, the light bulb is considered being more efficient here. Same here in audio department, we speak of sound emission as pressure.

Efficiency in vocabularies:
Efficiency is the quality of being able to do a task successfully, without wasting time or energy.
the state or quality of being efficient, or able to accomplish something with the least waste of time and effort; competency in performance.
EFFICIENT is productive of desired effects.
The efficiency of a device is the proportion of the energy supplied that is transferred in useful ways.
Efficiency is the ratio of the work performed by a machine to the total energy expended.
And so the task here is to make acoustical pressure, supposedly. You can also find more blunt descriptions of power in/power out ratio, but then we have two competing descriptions, and one does not discredit the other one. My claim might be clearly dismissed, but it doesn´t mean it doesn´t have merits or proper meaning. Now if we need to sort it out and be more precise, we indeed call the current state "energy efficiency" or "power efficiency". This though was not claimed explicitely yet, rather mistakenly.

Sometimes one part of that system can be made super efficient, but to get there we need another system that has poor efficiency.
Meaning that the sum of both systems isn't that efficient.
This has been debunked in my case. It still is energy efficient. But the energy is not a measure we are after. As energy does not scale well with sound(pressure).

Or if we consider a less simplified version, the high efficiency will only be a part of range of interest.
Much more so if we are gonna take 3D space (angles) into consideration etc etc.
This was equalized, can be substracted from the scope of view, disregarded completely.

But you can't just simply change the well established definitions of physics that way.
Indeed, that would not work out. We worked out what I am doing and what needs to be done on our way.
As quoted, we might not have settled what efficiency is then, as vocabularies claim different descriptions, and indeed, maybe we can let it be, but then I am pointig out on the fact that we might need and want something else than raw efficiency, or have it IN ADDTION, to get to the useful data, to develop our systems properly.

It basically evolved from change request into addition request then. Both might be dismissed, alright, but very valid point was made.
All it takes is recognition, and not even loud one. Just implied acknowledgement. Mostly I see pure dismissal with added snark. That´s not good view of "academic field" indeed. My job is done here - I learned a lot, and some people maybe too. Could not end up better. Many thanks for the teachings, remarks, showing of ways, and indeed showing different angles of view on things. I might leak some of the gaslighted mood into the discussion as it was originally me who proposed different view to be considered. Now me being asked of that is kind of irony. But even the irony needs to be taken and examined, dealt with and learned from.

Not going to hog it here much more, not my thread.

Last edited:
1 user

#### b_force

We might not be talking about energy efficiency
We are

because the desired efficiency marker basically "cannot" be expressed by ratio or percentage.
Than it's simply not efficiency.
Which btw, is not an opinion open for discussion, but dictated by definitions of physics.

Example. We want to illuminate an area or object efficiently. I chose a light bulb, someone else choses a LED. The LED used is UV or IR.
That is not called efficiency.
What you're describing is called (luminous) efficacy.
That being said, as I described before, it's absolutely important to describe the entire context.
Which is what I meant with simplified and advantage takes on the story.

Meaning we can talk about the total system efficiency, or only look at a specific portion of it.
It only changes the context and outcome, not the fact that the unit is dimensionless.

This has been debunked in my case.
Nothing is debunked, physics still holds, universe is still not falling apart.

As quoted, we might not have settled what efficiency is then,
This is a very well understood definition for hundreds of years?
So you're saying everyone was wrong all along?

Efficiency in vocabularies:
In physics we most definitely don't care what the average Joe THINKS certain definitions are.
So quoting such thing is also totally meaningless.
Definitions are well established, agreed upon and therefor used as such.
Those can be found in proper and respected sources/literature.

Sometimes those things clash with every day vocabulary.
Again, that is totally irrelevant for physics and should be dismissed.
Every day vocabulary is most definitely NOT defining definitions here!

I think this also describes the problem very well.
You simply can't mix up definitions of physics with subjective public ideas and vocabulary.

Fact is, we are talking physics here.

1 user

#### Crashpc

We might not be talking about energy efficiency
We are
Certainly I wasn´t , and my input was a request to look at it. I saw what you are talking about, and I found an issue with it in relation to solve certain problematics. What you are talking about is not solving my problem. And I have the audacity to say that it doesn´t properly solve the same problem of many other people, who might look at it the same "wrong way". So I proposed something different while called it wrongly, then was corrected, but stayed on the problem.
Sorry if it was not understood. Many topics mixed, me not being native speaker, could misled some.

That is not called efficiency.
What you're describing is called (luminous) efficacy.

Well, I did mention before already that our issue also turns around terminology. This is great example. That might be the addition I wanted.

Now, Not so easy. If we were to filter out the invisible spectrum in my proposal and measured power on the output side, We should still have power in vs power out ratio, which would comply with the meaning of the word efficiency. In the black box system, where you are only to measure ins and outs, it will clearly appear and will handled as efficiency. Now what?

Meaning we can talk about the total system efficiency, or only look at a specific portion of it.
It only changes the context and outcome, not the fact that the unit is dimensionless.
I was asking for the intended output to be dimensionless already. I just knew that in the presented state, it wasn´t possible, as decibels do not translate to that.
This is the issue of imprecise speech. Well, we could include heat as well. Because heat in Watts is dissipated. Why exclude that in the effficiency claim? Because it is not useful to our goals. So do we exclude heat or not? Why we can exclude some, and we can´t exclude others? Because one is closer to the goal?
Again, sincerely asking for help and definition. Didn´t happen yet and so curious me is digging, and digging hard as much as it can be painful to suffer for some.

This has been debunked in my case.
Nothing is debunked, physics still holds, universe is still not falling apart.
This clearly was not understood. I mean what you described basically did not happen in my system. The claim could not be applied on my case as it wasn´t happening. I did not dismiss any physical phenomena that could potentially happen.

In physics we most definitely don't care what the average Joe THINKS certain definitions are.
So quoting such thing is also totally meaningless.
Definitions are well established, agreed upon and therefor used as such.
Those can be found in proper and respected sources/literature.
Respect is not a fact, and it wasn´t even linked or showed the object of the respect, to respect... I cannot respect no source, as none was given. The claim needs to come from unbiased source as data, and best be syntetized on the spot, to be genuine, truthful and not biased. At least, I would kindly ask for such source. If it wasn´t understood, I am asking for such sources. That would make the discussion much shorter.

I think this also describes the problem very well.
You simply can't mix up definitions of physics with subjective public ideas and vocabulary.

Fact is, we are talking physics here.
Indeed, that´s why I dropped that in a way and allowed for the possibility to call it differently.

The more I dig, the more the "conversion efficiency" term pops up independently to what mr.Mcbean proposed. He certainly knows his schtick.

Last edited:

#### b_force

At least, I would kindly ask for such source. If it wasn´t understood, I am asking for such sources.
Any high-school physics book?

But fine, I won't send people in the woods;

• Acoustics, L. Beranek
• Some kind of physics books that involves basics for thermodynamics and control systems.
Sorry, I can't remember what they use in schools these days, has been faaaar to long ago.

Well, I did mention before already that our issue also turns around terminology.
No it means that some people just don't know the basic definitions, nor do understand what proper literature means.
Which is fine, we are all here to learn. So absolutely zero defense.

It's important to remember that it's not realistic to expect others, especially someone like mr McBean, to provide a crash course on these topics.

Just because someone has their own interpretation of certain concepts doesn't mean others are obligated to defend well-established scientific standards.
If you're interested in engaging in certain discussions, it's a good idea to do some reading first.
Take the time to verify if what people are saying is accurate rather than insisting on your point because you believe they are wrong.

Again, it's important to see and understand both sides of the discussion.

Firing back a defense straight away, is NOT understanding.
Even more so when you're mixing up public vocabulary with actual physics.
That simply doesn't belong in any discussion about physics.
Respect is not a fact,
This is just being pedantic and very silly.
Unless you want to doubt literally any resource and book in the world?

I understand you might have some doubts or questions about the subject we're discussing, but it's important to note that these concepts are based on fundamental and well-established principles of physics.
These principles are supported by the work of millions of scientists who have dedicated their lives to studying and understanding these topics.

I realize this might not be how you intend it, but your comments could come across as questioning the foundational aspects of physics or the expertise of those who study and devote a lot of time to this?
Some people on this forum have spent years studying physics, engineering, or related sciences and even have a degree in those.

For those with a background in these fields, there's often not much discussion on the basics, as they are established facts and not "just" opinions.
This can sometimes be a point of misunderstanding for those who are newer to the topic or come from different backgrounds.
Therefor you simply just can't always point to "one source" to prove a point.

Of course, you're free to question and explore these ideas.
Just keep in mind that certain things in science, like the fact that the Earth is not flat, are well-supported by evidence and not subject to personal opinion.

But sure, you're free to doubt that, that's a fundamental right.

#### Booger weldz

I think it’s incredibly intersting to try and discover different port size/shape or ‘TL’ that might sum better with the driver? Is this why ‘tapped pipes’ are a bit more ’spicy’ at ressonsce compared to a pipe with the vent a1/4 wavelength away from the driver?

if so, how could we compare/contrast This using horn response?

#### Crashpc

It's important to remember that it's not realistic to expect others, especially someone like mr McBean, to provide a crash course on these topics.
In this case asking is more eventual, not an expectation for getting crash course.

Even more so when you're mixing up public vocabulary with actual physics.
That simply doesn't belong in any discussion about physics.
That´s a low jab. I did engineering in electronics, acoustics and optics and also devoted big part of my life to it. Peer reviewed, customer reviewed, customer engineering reviewed, audited, benched, produced and worked for population. My work did fly, no issue there. Could we/they be all wrong? They could, although planes are flying and trains are rolling and ultrasound devices ultrasounding. But so anyone also devoting his part of life to stuff could be wrong. People are wrong all the time. This is just cheap shot really. The wording of your response is basically formulated as a way for going for persons reputation, no way around it. Conversion efficiency is still efficiency measure. Just the existance of it is proof enough as it is also backed up by science. I did not make it up. You go look it up if you do not understand that. Mr.Mcbean obviously understood the issue at hand. Just corrected me on the blunt terminology and his approach that also has obvious value and merits. Never thought we would end up here. God knows I tried. :-D

1 user

#### b_force

People are wrong all the time.
I don’t have anything against healthy skepticism.
In fact, it's a valuable trait.
However, distrusting any kind of information or people right from the start is a different matter.

Using and quoting everyday vocabulary (and therefor "definitions") doesn’t really fit in a technical discussion about physics.
It only makes the entire discussion rather vague, since it leads to miscommunication.

For the record, I’m not here to debate this; I’d much rather consult a reputable book or scientific literature if I have any doubts.

If you're truly familiar with the field, you likely already know the best resources without needing to ask.
So it totally beats me why asking for them to begin with?

But I agree, this goes rather offtopic, although it was already that from the start.

#### David McBean

The term speaker sensitivity is defined by voltage.

As explained earlier, the correct definition for loudspeaker sensitivity is:
At a given frequency:

Sensitivity is the SPL at a given distance (originally 1 metre) for a given reference power (originally 1 watt), expressed in decibels.

If the input was taken to be voltage rather than power, then the standard frequency response curve would also become the sensitivity curve. This is simply not the case.

Indeed input power versus decibels is also a "power sensitivity".

As explained earlier, SPL is a measure of pressure, not power:

SPL = 20 * Log10( Pressure / Reference_Pressure)

"Single source equivalent power conversion efficiency". THIS! How do we get to such number?

By rearranging the two formulas below, as given earlier:
SPL = 20 * Log10( Pressure / Reference_Pressure)

Pressure = (Power * c * rho / Area) ^ 0.5

Pressure = Reference_Pressure * 10 ^ (SPL / 20)

Acoustical output power = Area * Pressure ^ 2 / (c * rho)

To illustrate for the 4OHz system at 40Hz:

Electrical input power = 2023.9272 watts

Pressure at 1 metre in quarter space = (20 * 10 ^-6) * 10 ^ (132.6177 / 20) = 85.4897 pascals

Acoustical output power = Pi * 85.4897 ^2 / (344 * 1.205) = 55.3901 watts

Power conversion efficiency = 55.3901 / 2023.9272 * 100 = 2.7368 percent

3 users

#### BP1Fanatic

However, distrusting any kind of information or people right from the start is a different matter.
Yeah it is. Ask any Black person on the planet.

#### Crashpc

@David McBean
(ignored response is agreed upon).

If the input was taken to be voltage rather than power, then the standard frequency response curve would also become the sensitivity curve. This is simply not the case.
Well that´s what I was doing, and so I could afford to name it that way. The issue with reference voltage/power is that it is not comparative, as same nominal impedance speakers have both different Re and different impedance (static and in frequency too). I was working more in apples-to-apples realm, and indeed the nomeclature might not fit that way of working. I should have call that approach in advance. Sorry for confusion.

Power conversion efficiency = 55.3901 / 2023.9272 * 100 = 2.7368 percent
Oh, I missed the "Single source equivalent acoustical output power". That´s the merit of the issue. No more unpacking needed though.

Many thanks!

1 user

#### maxolini

I would be nice to get all those definitions and formulas in a sticky thread.

If you are still lost.... Ask.

I mean for people who do not want to dig in the books written about those subjects.

I understand that maybe you can't read more than 20 pages without getting a headache on those books.

But if you can't read a couple of pages in this forum because of mental laziness

Go find another hobby... 😁

Personally I have gone to those big threads like the single sheet th challenge ,
PAL30
the th18,
keystone and the

### C/E/X PA Flat to 30 (FT30) PA TH Awesomeness​

Threads several times from start to finish.
And can't understand a damn thing still 🤣🤣

Last edited: