Thanks for your comments Pete. Yes I did use VB.net to write the app.
I calculate the acoustic impedance of each element of the pipe and then add them all together in series. If you want to know in more detail I can, but maybe this thread isn't the best place.
Thanks for the suggestion about enclosure volume. I will also update the t/sninput as per your comment.
Cheers,
Pete
I calculate the acoustic impedance of each element of the pipe and then add them all together in series. If you want to know in more detail I can, but maybe this thread isn't the best place.
Thanks for the suggestion about enclosure volume. I will also update the t/sninput as per your comment.
Cheers,
Pete
Hi Pete,
Please don't abandon the parameter set you have now, but please expand with the ability to cross calculate.
I too have some interest in the programming if it is open to discussion somewhere.
If you really must have the much more unconventional parameter input I'd say use a switch check box to select the format rather than trying to guess at which one is the input value. Something like a check box for standard T&S vs. mechanical parameters. I think it would just confuse things otherwise.
Pete you might also put a comment on the SPL graphs for the power input assumed, and really isn't it constant voltage so not really power? Giving power that is really constant voltage means we need to know the assumed load resistance or do you always use an 8 ohm reference? You might just give both, something like 100W - 28.3Vrms.
Once again Pete, thank you so much for this excellent tool!
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I know how to do this since I had to figure it out the first time around where I had to think long and hard about it - it took me a while to figure this out. I spent many long hours reading the classic papers.
Here are the steps for the case with no driver offset (driver is at the start of the line) in case anyone is interested; Pete please let me know if you agree:
1. Calculate the radiation impedance of the port
2. Load the last section with the above impedance and calculate the input impedance.
3. Load the next closer section with that input impedance as the termination impedance.
4. Continue until you get to the line input impedance loading the driver.
5. Compute the volume velocity vs. frequency for the driver loaded by the first section input impedance.
6. You now have the volume velocity of the speaker cone.
7. Compute the first section volume velocity transfer function from input to output as loaded by the next section.
8. Repeat and compute all section transfer functions as loaded by the next section and finally the port.
7. Take the negative (back side of cone) of the cone volume velocity and use it as the driving source for the first section of line to compute the first section output volume velocity.
8. Repeat using each sections volume velocity transfer function until you get to the port output.
9. Plot cone and port output and vector sum them to get the total system output converting volume velocity to SPL at the assumed distance.
,
At the minute , you enter the other parameters and these are then calculated. I think I will try and change this so you can enter the more 'conventional' parameters and the others are calculated. Haven't decided quite how it will work yet though..
Oh, now that will throw you out of whack with most other models out there. I recommend input boxes for Voltage, Nominal Impedance, & Power, enter any two.
I see, it would be very helpful to have the computed RMS input voltage displayed somewhere or both as I said earlier. Most plot for 2.83 Vrms in, just to show the
standard voltage sensitivity, but power is fine also.
Thanks for the suggestions guys.
Version 2.3 has just been uploaded (as before you can update from the about window).
I have added units to the enclosure window, as well as the calculated internal volume.
I have also adjusted the driver t/s inputs so you enter the more conventional inputs. i will try and do an option to change between which set of parameters you enter.
I will also give you the option of voltage or power when I get round to it. Do you think it is worth giving another option for impedance, even though this is specified in the T/S parameters?
Got to do some real work now, I'll check back in a bit!
Pete
Version 2.3 has just been uploaded (as before you can update from the about window).
I have added units to the enclosure window, as well as the calculated internal volume.
I have also adjusted the driver t/s inputs so you enter the more conventional inputs. i will try and do an option to change between which set of parameters you enter.
I will also give you the option of voltage or power when I get round to it. Do you think it is worth giving another option for impedance, even though this is specified in the T/S parameters?
Got to do some real work now, I'll check back in a bit!
Pete
Actually, Pete if I am remembering correctly T&S did use Re for calculating input Pe when displaying power limited output. It is just a rough worst case approximation, but I think it is better than using Znom which can be anything. Znom is not a T&S parameter, don't think I've seen it on a data sheet but if it is there it is a marketing parameter.
T&S Papers online:
http://www.readresearch.co.uk/articles.php
T&S Papers online:
http://www.readresearch.co.uk/articles.php
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Suggestion. Copy this approach:
http://www.diyaudio.com/forums/subwoofers/119854-hornresp-137.html#post2275173
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