Hornresp

the download site still says 110816 but the download works with 110818

Hi Ted,

I suspect that your Internet Browser settings are such that they do not automatically check for newer versions of stored pages each time a site is visited.

The Hornresp download site Product Number was / is definitely correct - I can guarantee it :).

Kind regards,

David
 
I kwow the single segment trick, but is there a reason that it is impossible to use with multiple segments or reflex design ? Too complicate to be programmed? thank.

Hi julienb34,

To accurately simulate the directivity of a multiple segment horn or the combined response of a bass reflex loudspeaker would require a completely different model to that currently used in Hornresp. Boundary Element Method (BEM) techniques could be used, but the downside would be the very long calculation times. For that reason, I have no plans to change the Hornresp directivity model - even though I have done some experiments calculating directivity using BEM techniques (see attached example).

Kind regards,

David
 

Attachments

  • Pattern.png
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Hi, thank you for the updates to Hornresp.

I'd like to suggest a parameter for listening distance affecting SPL levels.

As a beginner I also found the maximum SPL Watt entry a bit confusing. I wondered if it was combined Watts or individual?
For example I could use two individual amplifiers for two drivers or one amp with the drivers connected in parallel for one box (as is suggested currently by Hornresp I think)?
 
Hi David,
Thanks for the new features!!!

@vadi
:beady:
Not to be mean but it's hard enough to understand what is being posted, I for one could do without distance. I am invisioning Noobies posting .25m .25pi charts. For clarity I'd like to see the voltage and radiation angle(1pi,2pi) imprinted in the header or footer of the graphs. Besides distance is already used for pathlength difference in parts of Hornresp.

Drivers powered by individual amps and parallel connection = same output for same input voltage.
 
Hi vadi,

I'd like to suggest a parameter for listening distance affecting SPL levels.

The generally accepted standard normalised reference distance is 1 metre. Allowing this to be changed by the Hornresp user might lead to confusion when different loudspeaker systems are being compared. All things considered, I think it is probably safer to leave SPL results as they are - normalised to 1 metre :).

If you wish, the SPL at distance D metres given the SPL at 1 metre, can be calculated as follows:

SPL(D) = SPL(1) - 20 * Log10(D)

For example - if the SPL at 1 metre is 100 dB, then the SPL at 10 metres will be:

SPL(10) = 100 - 20 * Log10(10)
SPL(10) = 100 - 20 * 1
SPL(10) = 80 dB

Because of the inverse square relationship, SPL falls off at the rate of approximately 6 dB for each doubling of distance away from a point source.

1 metre = 0 dB
2 metres = -6.02 dB
4 metres = -12.04 dB
8 metres = -18.06 db

As a beginner I also found the maximum SPL Watt entry a bit confusing. I wondered if it was combined Watts or individual? For example I could use two individual amplifiers for two drivers or one amp with the drivers connected in parallel for one box?

The Maximum SPL watt entry is the Pmax value for a single driver.

Hornresp always assumes a single amplifier.

As indicated on page 14 of the Help file, Pmax is the rated thermal limited electrical input power of the driver. If Pmax is specified as 100 watts by the user (see attachment 1), then for two drivers in series or parallel (it doesn't matter which), Hornresp automatically sets the total electrical input power into the system to 2 x 100 = 200 watts (see sample results in attachment 2).

Kind regards,

David
 

Attachments

  • MaxSPL1.png
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  • MaxSPL2.png
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For clarity I'd like to see the voltage and radiation angle (1pi,2pi) imprinted in the header or footer of the graphs.

Hi Dan,

I took the decision very early on, as a matter of principle, not to include anything on the chart windows that was already shown on the input parameters window. It would be difficult to know where to draw the line - if Eg was to be shown, then perhaps Rg should be shown also, and perhaps the driver configuration.

When a chart is printed as a hard copy however, all the input parameter values are included in the output, as part of the permanent record.

Kind regards,

David
 
I have a comment on the distance from the horn mouth.

Many individuals including myself have noted that a horns true response cannot be measured properly in the near field.

When measuring below about 300hz the wavelength of the frequency and the output from the horn seem to require a greater measurement distance in which to get an accurate representation of what horn does under normal useful conditions. Trying to measure 20hz at one meter generally looks ugly ragged and terrible. Take the same measurement out a distance and correct for the losses as David showed and you get a more accurate representation of what your box is doing.
 
When measuring below about 300hz the wavelength of the frequency and the output from the horn seem to require a greater measurement distance in which to get an accurate representation of what horn does under normal useful conditions. Trying to measure 20hz at one meter generally looks ugly ragged and terrible. Take the same measurement out a distance and correct for the losses as David showed and you get a more accurate representation of what your box is doing.

Just to clarify - the "losses" Mark refers to are due to the sound energy being radiated into a larger surface area, resulting in the intensity and hence the pressure being reduced at the measuring point. None of the propagated sound power is actually lost.

With bass horn loudspeakers it is desirable to measure the SPL several metres from the horn mouth, ideally under anechoic conditions, and then normalise the results back to the standard reference distance of 1 metre.

For example, if the SPL measured at 7 metres is 90 dB, then the value normalised back to 1 metre would be:

SPL(1) = SPL(7) + 20 * Log10(7)
SPL(1) = 90 + 20 * 0.845
SPL(1) = 90 + 16.90
SPL(1) = 106.90 dB

Kind Regards,

David
 
Does anyone know why Hornresp gives different results than this spreadsheet:
Download Section
for tractrix horns? I was inspired by the spreadsheet because a 60Hz horn was so nice and short, but Hornresp made it much bigger. One shows a length of 67.1cm and the other shows a length of 161cm! The expansion curve of the spreadsheet has the 90 degree flare at the mouth whereas the generated by Hornresp does not.

I don't know which one is correct. A lot of people use the spreadsheet, from what I have seen. I gave up and anticipate building a 100 Hz hyp-ex instead. It's 105cm long.
 

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  • 12PE32 tractrix spreadsheet.JPG
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  • 12PE32 60Hz tractrix input 2 screen.JPG
    12PE32 60Hz tractrix input 2 screen.JPG
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Even if I set it "1", I get a horn length of 1.96 meters, which is different than Hornresp.

Hi dirkwright,

Have a look at the formula in the spreadsheet used to calculate Rm (mouth radius). The velocity of sound value used here is 340 m/sec. Change this to 344 m/sec and you will now get effectively the same results as those calculated by Hornresp - allowing for the very slight differences in mouth area and length due to rounding.

Spreadsheet:

Fc = 60 Hz
Placement = 1
At = 178.8 sq cm
Am = 26158.0 sq cm
Length = 199.63 cm

Hornresp:

S1 = 178.80 sq cm
S2 = 26157.99 sq cm
L12 = 199.62 cm
F12 = 60 hertz

Kind regards,

David