Piper said:I did do that, just I didn't know what it was really asking for and how to work out
1: CMS - driver diaphragm suspension mechanical compliance (m/N)
2: MMD - driver diaphragm and voice coil dynamic mechanical mass (m/N)
I asume MMD is refering to the magnet mass and cone mass but how the hell do you get it into units of m/Newton i.e. distance/force
You double click on the box and fill in the parameter is asks for and HornResp calculates it for you. This is available for CMS, MMD, BL, RMS which makes the minimum parameters required for HornResp only Sd, Vas, Fs, Qes, Qms and Re
ah sorry johnin was being a fool, have changed the CMS and MMD parameters but as Rademakersu thought it hardly changes the simulated responce. Im still getting no where near what i should even with every thing entered correctly.
Does any one know how accurate Hornresp is, or of any where i can get the information to plot the responce my self.
Sorry to be a pain with all these questions but i dont like letting programes do all the working out for me if i cant check what its doing. 😀
Does any one know how accurate Hornresp is, or of any where i can get the information to plot the responce my self.
Sorry to be a pain with all these questions but i dont like letting programes do all the working out for me if i cant check what its doing. 😀
Did you correct your chamber volumes? As was stated earlier, the boxes are in CC's not liters, so your original screen shot was off by a factor of 1000.
While hornresp isn't perfect, it should give you a pretty good idea.
What it's not going to predict is compression problems from too small a throw or the effects of having such a tall narrow pathway through your horn. It will allow you to play around with your chamber volumes although I don't think that's the problem. Bigger compression chambers generally means more bass, but they start acting like a ported box in some ways causing distortion.
Start with getting all your input right in HornResp first. If it is saying you should get a good response with what you have, then you have a leakage, compression, and/or wiring problem, all of which are easily fixable. I suspect though that HornResp is going to tell you that your horn is too short and your mouth is too small.
Did you put it firing into a corner when you tested it out? With a small mouth like that, corner loading would be the only chance for success.
While hornresp isn't perfect, it should give you a pretty good idea.
What it's not going to predict is compression problems from too small a throw or the effects of having such a tall narrow pathway through your horn. It will allow you to play around with your chamber volumes although I don't think that's the problem. Bigger compression chambers generally means more bass, but they start acting like a ported box in some ways causing distortion.
Start with getting all your input right in HornResp first. If it is saying you should get a good response with what you have, then you have a leakage, compression, and/or wiring problem, all of which are easily fixable. I suspect though that HornResp is going to tell you that your horn is too short and your mouth is too small.
Did you put it firing into a corner when you tested it out? With a small mouth like that, corner loading would be the only chance for success.
yeah i did get everything entered in correctly now and my results are almost the same as the second graph on the previous page, i must admit i didnt test it in corner. Im gonna make my chages then see what happens.
Do think i should loose the isobaric config and push the speaker right upto the troat
Or
Keep the iso and try to reduce throat chamber down ?
Do think i should loose the isobaric config and push the speaker right upto the troat
Or
Keep the iso and try to reduce throat chamber down ?
Try varing the chamber sizes in HornResp and see if that improves the predicted result before doing anything.
Not much in it but the smaller vol in chamber gives a flater response which is generaly higher, the volume that i have (currently) gives peaks at 40HZ and 150 HZ, and dips between these valuse.
After a day of listening im sure the throat aint sealed in properly, at certain freqs I hear a tinny rattle, the rest of chamber (the out side that i can see) is sold as a rock so thinking it must just not have lined up propely.
Here are some more pics
After a day of listening im sure the throat aint sealed in properly, at certain freqs I hear a tinny rattle, the rest of chamber (the out side that i can see) is sold as a rock so thinking it must just not have lined up propely.
Here are some more pics
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
seat-o'-pants appraisal by eye:
- mouth is way way way too small
- fs of driver is too high(?) (seems likely)
{how low did you want this to work?? I have mid horns with more mouth area!}
- throat looks to my eye like not a throat... no compression taking place?
- perhaps better to model as a long expanding TL??
neat work, looks neat... not sure why the isobaric?? did you try
a standard cone w/ throat first?? perhaps scale it up like 30% once you fix the throat, and make the mouth about equal to the entire side of the box, or bigger??
_-_-bear
PS. you'll get the best results for a too small mouth when it is coupled to the floor as an extension of the mouth expansion, and even better when coupled to the floor and the wall...
- mouth is way way way too small
- fs of driver is too high(?) (seems likely)
{how low did you want this to work?? I have mid horns with more mouth area!}
- throat looks to my eye like not a throat... no compression taking place?
- perhaps better to model as a long expanding TL??
neat work, looks neat... not sure why the isobaric?? did you try
a standard cone w/ throat first?? perhaps scale it up like 30% once you fix the throat, and make the mouth about equal to the entire side of the box, or bigger??
_-_-bear
PS. you'll get the best results for a too small mouth when it is coupled to the floor as an extension of the mouth expansion, and even better when coupled to the floor and the wall...
Yeap i now know the compresion ratio was way to small (and i wasnt really looking for a massivly low response), but i stupidly based the throat size on the equation on this web site
http://melhuish.org/audio/horndesign.html
area throat = (2pie*Fs*Qts*Vas)/c
This was my very frist look at horn speakers so i trsuted what was written. And of coures all my other calcutions where based on this small throat area. So everything else would also be wrong -
As yet no one has been able to tell me if this equation is worng ?
http://melhuish.org/audio/horndesign.html
area throat = (2pie*Fs*Qts*Vas)/c
This was my very frist look at horn speakers so i trsuted what was written. And of coures all my other calcutions where based on this small throat area. So everything else would also be wrong -
As yet no one has been able to tell me if this equation is worng ?
Dunno... I'd have to haul out my horn documentation...
There is variability in the optimal throat dimensions though...
My main point, I think you missed... the mouth size is too small
to properly support any LF extension at all. So, the result is that
ur speaker is more like a TL than a horn - which partially explains
the lack of gain.
Also, the best response from less than full sized bass horns will come from hyperbolic expansions, where the LF extension is "extended" by the appropriate volume behind the driver...
_-_-bear
There is variability in the optimal throat dimensions though...
My main point, I think you missed... the mouth size is too small
to properly support any LF extension at all. So, the result is that
ur speaker is more like a TL than a horn - which partially explains
the lack of gain.
Also, the best response from less than full sized bass horns will come from hyperbolic expansions, where the LF extension is "extended" by the appropriate volume behind the driver...
_-_-bear
The equation is fine. The problem in your case is that using the Iso loading's Vas, just ends up with too small a throat size in relation to Sd. If you want to increase the throat somewhat quite easily, just bend the top edge of your metal piece toward the driver. Make so the top edge runs parallel to the next turn of metal up to the baffle. That should give you a 50% or so increase in the throat area with little, if any affect on your horn.
This time test it first before permanently attaching the top cap. I'd also position it in the corner in such a way that the corner forms an extension of the horn mouth giving you more effective length and mouth area.
This time test it first before permanently attaching the top cap. I'd also position it in the corner in such a way that the corner forms an extension of the horn mouth giving you more effective length and mouth area.
Thanks very much for all your help, i increased the troat size and resealed every thing. These were my final results.
If it wasnt for that huge dip at 115Hz i would have been happy with it. But think im gonna call it a day on this one and start work on a larger coiled horn, no iso loading this time and some more efficent drivers
If it wasnt for that huge dip at 115Hz i would have been happy with it. But think im gonna call it a day on this one and start work on a larger coiled horn, no iso loading this time and some more efficent drivers
The efficiency isn't the significant factor when it comes to horns. You can easily have a horn, loaded with a 89 dB/W/m driver giving a higher SPL than a 99 dB/W/m driver, as long as the other T/S-parameters are right.
Btw: Mmd is just in grams
Sounds like a good idea 😉
Mvg Johan
optimum throat size
I have had problems with throat size calculations too.
I use Bruce Edgars version. Same, just less problems with units!
St= 0.8 Fs Qes Vas
where Vas is in cubic feet
St is in square inches
and Fs is the FLARE FREQUENCY
Regards Philip
I have had problems with throat size calculations too.
I use Bruce Edgars version. Same, just less problems with units!
St= 0.8 Fs Qes Vas
where Vas is in cubic feet
St is in square inches
and Fs is the FLARE FREQUENCY
Regards Philip
What are the mian T/S-parameters i should look for in a horn loaded speaker ?
Obviously i would assume the need for a large Vas and Qts.?
Obviously i would assume the need for a large Vas and Qts.?
vas and qts
I would look for drivers with the lowest Qes. This will give the horn a higher mass rolloff. As you can see by the throat equations, bigger qes and Vas also means a bigger throat and therefore a shorter horn.
small Vas will give a longer horn. A horn needs to be at least 1/4 of a wavelength long to work, longer is even better.
Regards Philip
I would look for drivers with the lowest Qes. This will give the horn a higher mass rolloff. As you can see by the throat equations, bigger qes and Vas also means a bigger throat and therefore a shorter horn.
small Vas will give a longer horn. A horn needs to be at least 1/4 of a wavelength long to work, longer is even better.
Regards Philip
If your making a horn that has to do it on it's own (instead of being designed to work best in multiples), while it's limited in size, it's better to use a driver with a Qts that isn't too low (low would be 0.22 or alike).
In such a case your looking for a driver with a Qts between (about) 0.27 - 0.35 orso and a BL that's normal to high (depends on diametre used) but not exceptional. Very important (espescially) in this case is the Xmax.
More Xmax means more output potential. This translates in higher SPL and/or more low end extension. Look at drivers with at least around 7 mm Xmax, to get low end at desired levels. Serious drivers will have plenty Xmax (say 12 mm+)
If you're making a horn, design it to be used in 1/4 or even 1/8 th space if possible.
Basshorns that work good on there own generally have a large rear chamber.
The bigger the Sd, the shorter you can make the horn for the same cut off, so it's better to use two drivers next to each other rather than isobaric.
The smaller the Sd, the bigger the compression ratio can be, but 4 would be the maximum and rather look for a driver that works good already with a compressionratio of 2 or less.
Simulate the hornmouth to be 6 or 7 times bigger than Sd. Than gradually work it to become smaller, using the compare function to see what the real minimum moutharea is.
Try to simulate with many drivers, some drivers just don't work well, despite good looking T/S-parameters. It will make you understand Hornresp and horn design basics much sooner tho.
BTW: ES is in Volts. So 2,83 (@8 ohm) equals 1 Watt per driver. Doubleclick to get a calculator that translates the power (in Watts) to Volts.
Mvg Johan
In such a case your looking for a driver with a Qts between (about) 0.27 - 0.35 orso and a BL that's normal to high (depends on diametre used) but not exceptional. Very important (espescially) in this case is the Xmax.
More Xmax means more output potential. This translates in higher SPL and/or more low end extension. Look at drivers with at least around 7 mm Xmax, to get low end at desired levels. Serious drivers will have plenty Xmax (say 12 mm+)
If you're making a horn, design it to be used in 1/4 or even 1/8 th space if possible.
Basshorns that work good on there own generally have a large rear chamber.
The bigger the Sd, the shorter you can make the horn for the same cut off, so it's better to use two drivers next to each other rather than isobaric.
The smaller the Sd, the bigger the compression ratio can be, but 4 would be the maximum and rather look for a driver that works good already with a compressionratio of 2 or less.
Simulate the hornmouth to be 6 or 7 times bigger than Sd. Than gradually work it to become smaller, using the compare function to see what the real minimum moutharea is.
Try to simulate with many drivers, some drivers just don't work well, despite good looking T/S-parameters. It will make you understand Hornresp and horn design basics much sooner tho.
BTW: ES is in Volts. So 2,83 (@8 ohm) equals 1 Watt per driver. Doubleclick to get a calculator that translates the power (in Watts) to Volts.
Mvg Johan
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