Hi Lars,
Mmd is included in the driver electro-mechanical simulation model.
The diaphragm air load is calculated separately in Hornresp, so there is no need for the Mms value.
Kind regards,
David
Hi Brian,
Thanks for the suggestions. After weighing everything up, I ultimately decided to leave things as they are
.
This means that the lumped-mass model only applies when Ap and Lpt are used to specify a port tube, and then only when certain dimensional constraints are met. In a compound horn configuration, S5 and S6 will specify a horn in all cases - even when S5 = S6.
To indicate when the lumped-mass model is being used, the Helmholtz resonance frequency is given (no Helmholtz frequency means that the lumped-mass model is not being employed). On the input parameters screen it is necessary to move the mouse pointer over either the Ap or Lpt input box to show the Helmholtz frequency in the status bar panel at the bottom of the form. In the Loudspeaker Wizard the Helmholtz frequency is displayed when the Chamber input option is selected.
The lumped mass model has two end corrections - one at the outlet and one at the inlet. In effect the horn model has the same "end correction" at the outlet (mouth), but none at the inlet (throat).
Under 0.5 x Pi conditions the end correction at the outlet is increased in length, thus reducing the impact of any end correction at the inlet. This is why the results for the two models become closer.
Kind regards,
David
Thanks for the suggestions. After weighing everything up, I ultimately decided to leave things as they are
.This means that the lumped-mass model only applies when Ap and Lpt are used to specify a port tube, and then only when certain dimensional constraints are met. In a compound horn configuration, S5 and S6 will specify a horn in all cases - even when S5 = S6.
To indicate when the lumped-mass model is being used, the Helmholtz resonance frequency is given (no Helmholtz frequency means that the lumped-mass model is not being employed). On the input parameters screen it is necessary to move the mouse pointer over either the Ap or Lpt input box to show the Helmholtz frequency in the status bar panel at the bottom of the form. In the Loudspeaker Wizard the Helmholtz frequency is displayed when the Chamber input option is selected.
The lumped mass model has two end corrections - one at the outlet and one at the inlet. In effect the horn model has the same "end correction" at the outlet (mouth), but none at the inlet (throat).
Under 0.5 x Pi conditions the end correction at the outlet is increased in length, thus reducing the impact of any end correction at the inlet. This is why the results for the two models become closer.
Kind regards,
David
Hi Lars,
Hornresp does not use Mms as a discrete value. Rather, Mmd is used instead with air loads being taken into account as required.
Given fs and Mms,
Mmd = Mms - air load at fs
In Hornresp the acoustical impedance of a rigid plane circular piston of area Sd vibrating at fs is used to determine the air load. The accurate calculation of the acoustical impedance in this case is not a trivial exercise.
Kind regards,
David
Hornresp does not use Mms as a discrete value. Rather, Mmd is used instead with air loads being taken into account as required.
Given fs and Mms,
Mmd = Mms - air load at fs
In Hornresp the acoustical impedance of a rigid plane circular piston of area Sd vibrating at fs is used to determine the air load. The accurate calculation of the acoustical impedance in this case is not a trivial exercise.
Kind regards,
David
I'm not McBean, but...
When playing around with it I found that
Mmd=Mms-(8*Density of Air*(Driver Sd/PI)^(3/2)/3)
For DoA I use 1.205 kg/m3
It comes darn close to what HR calculates. Say HR calculates 29.86, and I will get 29.88, or 458.17 in HR and 458.02 my way.
I have a hard time juggling i or j around, so I look for a way around it.
Hornresp Version 28.40
Hi Everyone,
Hornresp now exports template lengths for the top and side walls of any square or rectangular cross-section horn.
Version 28.40 refers.
Kind regards,
David
Hi Everyone,
Hornresp now exports template lengths for the top and side walls of any square or rectangular cross-section horn.
Version 28.40 refers.
Kind regards,
David
Hello Soho,
About the formula you indicate which is often used to estimate Mmd from the measurement of Mms :
Mmd = Mms - Mma
As an example in the datasheet for the TAD TL1601 loudspeaker
Mms is given at 116g
and
Mmd is given at 85g
Using the formula Mmd = Mms-Mma
with Mma being the air load we obtain Mmd = 100g or so.
Why such discrepancy?
In fact we have to take care on the method used to measure Mms.
If we use the loudspeaker unbaffled then
Mmd = Mms - Mma
bu when we use a large baffle or a closed box then the formula becomes:
Mmd = Mms -2.Mma
When the loudspeaker is unbaffled an acoustic short circuit appears and the loudspeaker beahaves as only one side of the cone was loaded by the air.
When the loudspeaker is baffled with a large baffle or measured inside a closed box, the loudspeaker beahaves as the 2 sides of the cone was loaded by the air.
So every measuremnts of Mms should specifies how the measurement is done.
For the TAD TL1601 the measurement of Mms was performed with a closed box or a very large baffle.
Best regards from Paris, France
Jean-Michel Le Cléac'h
About the formula you indicate which is often used to estimate Mmd from the measurement of Mms :
Mmd = Mms - Mma
As an example in the datasheet for the TAD TL1601 loudspeaker
Mms is given at 116g
and
Mmd is given at 85g
Using the formula Mmd = Mms-Mma
with Mma being the air load we obtain Mmd = 100g or so.
Why such discrepancy?
In fact we have to take care on the method used to measure Mms.
If we use the loudspeaker unbaffled then
Mmd = Mms - Mma
bu when we use a large baffle or a closed box then the formula becomes:
Mmd = Mms -2.Mma
When the loudspeaker is unbaffled an acoustic short circuit appears and the loudspeaker beahaves as only one side of the cone was loaded by the air.
When the loudspeaker is baffled with a large baffle or measured inside a closed box, the loudspeaker beahaves as the 2 sides of the cone was loaded by the air.
So every measuremnts of Mms should specifies how the measurement is done.
For the TAD TL1601 the measurement of Mms was performed with a closed box or a very large baffle.
Best regards from Paris, France
Jean-Michel Le Cléac'h
Hi,
When calculating my 414-8a with Mms=35,6gr I get Mmd=28gr. This makes sense.
Still, what on earth do we need Mmd for, when calculating a Hypex horn according to Marshall Leach? I have earlier shown Mmd and Cmd in his AES-paper is Mms and Cms.
David, About Hornresp, is Mmd used for HF response or anything else?
When calculating my 414-8a with Mms=35,6gr I get Mmd=28gr. This makes sense.
Still, what on earth do we need Mmd for, when calculating a Hypex horn according to Marshall Leach? I have earlier shown Mmd and Cmd in his AES-paper is Mms and Cms.
David, About Hornresp, is Mmd used for HF response or anything else?
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Hello Jmmlc,
I wasn't using that equation to get to where I did, but it's nice to know I wasn't of my rocker.
You have touched on a topic that I don't remember this popping up here in this thread yet. I'm on break, so I can't send much time on it right now, but the joys of alternate parameter measurement methods should be broached.
I would assume you convert the parameters for entry into HR, as opposed to use entering the factory numbers, and running with it.
As it is, the purpose of my post was to help revintage keep his Hornresp section active in his spreadsheet. In that vain when pulling Mms from Fs and Vas it will give you the same calculated answer HR will.
I wish I had more time to play these days.
I wasn't using that equation to get to where I did, but it's nice to know I wasn't of my rocker.
You have touched on a topic that I don't remember this popping up here in this thread yet. I'm on break, so I can't send much time on it right now, but the joys of alternate parameter measurement methods should be broached.
I would assume you convert the parameters for entry into HR, as opposed to use entering the factory numbers, and running with it.
As it is, the purpose of my post was to help revintage keep his Hornresp section active in his spreadsheet. In that vain when pulling Mms from Fs and Vas it will give you the same calculated answer HR will.
I wish I had more time to play these days.
Hi Lars,
Mmd is not required for the Marshall Leach horn calculations.
Mmd is one of the fundamental mechanical parameters used in Hornresp to define the driver model. Its value influences all chart outputs to some degree (apart from throat acoustical impedance).
It is not a question of selectively using Mmd for a particular purpose - it forms an integral part of the overall loudspeaker model, and is therefore automatically taken into consideration in all simulation calculations.
Kind regards,
David
Mmd is not required for the Marshall Leach horn calculations.
Mmd is one of the fundamental mechanical parameters used in Hornresp to define the driver model. Its value influences all chart outputs to some degree (apart from throat acoustical impedance).
It is not a question of selectively using Mmd for a particular purpose - it forms an integral part of the overall loudspeaker model, and is therefore automatically taken into consideration in all simulation calculations.
Kind regards,
David
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@revintage
for a closer descrition for MMD, MMs, Vas, Re, Rms, etc., take a look at the wikipedia and search for "thiele small parameters". The english version is quite good.
For a guick intro to the Marshall Leach horn equation, look here: Horn Design
You can see, that the mass of the cone is not used in the formulas..
for a closer descrition for MMD, MMs, Vas, Re, Rms, etc., take a look at the wikipedia and search for "thiele small parameters". The english version is quite good.
For a guick intro to the Marshall Leach horn equation, look here: Horn Design
You can see, that the mass of the cone is not used in the formulas..
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"For a guide intro to the Marshall Leach horn equation, look here: Horn Design"
Why on earth should I look into that?? It is badly written, giving no help to a future Hypex designer.
If you go few pages back you will also find, I found errors in Leach AES-paper as it is what I have used doing my "Hypex Optimizer". The dicussion started after David had tried it found our results being equal except for one of the export functions. .
Also Mmd is not a Thiele/Small parameter. But you probably know that.
Why on earth should I look into that?? It is badly written, giving no help to a future Hypex designer.
If you go few pages back you will also find, I found errors in Leach AES-paper as it is what I have used doing my "Hypex Optimizer". The dicussion started after David had tried it found our results being equal except for one of the export functions. .
Also Mmd is not a Thiele/Small parameter. But you probably know that
.
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Had a typo.. I meant "quick" intro, not "guide"
Of course, if you read the original, there is no better source.
If you had read the discussion from the beginning(post#1797) you should have been aware of that
.Hi Sabbelbacke,
Not directly, but the value of fs will be dependent on the value of Mmd....
Kind regards,
David
Not directly, but the value of fs will be dependent on the value of Mmd...
.Kind regards,
David
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Hi brsanko,
When calculating combined response, Hornresp assumes that the horn output and the direct radiator or port output are two separate sound sources. The advisory notes were included in the Combined Response section of the Help file to caution users that predictions may be less accurate when the two outputs are "pre-mixed" inside the horn mouth.
There is nothing to prevent you from actually building such a system if you wish, however
.Kind regards,
David
Hi brsanko,
Further to my comment above - a direct radiator or port outlet positioned inside the horn mouth will experience some degree of horn loading. The loading will be dependent upon the precise location and orientation of the direct radiator or port outlet within the horn. Since this information is not known by Hornresp, the predicted combined response may not be entirely accurate.
Kind regards,
David
It's about a offset driver horn. I have made two 90 degrees folding to my horn. It is there possibility to significant changes to SPL response? All the areas and the lengths are correct, but is there some problems in the shape?
EDIT: used response will be 30-120hz
EDIT: used response will be 30-120hz
An externally hosted image should be here but it was not working when we last tested it.
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Hi brsanko,
There is nothing to prevent you from actually building such a system if you wish, however
Kind regards,
David
So what effects generally would this configuration have. I know from the benifit side it would create something much more closely resembling a point source on a much wider bandwidth, but I imagine nulls due to phase issues whould be exaggerated. I just don't quite know how to minimize these, or how to tell when they have been minimized. Any tips on the subject would be appreciated.