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post #1 of 3 Old 11-29-2018, 06:48 PM - Thread Starter
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Learning WinISD...A couple of questions

Hey guys,

I'm learning the basics of sub design and am doing some modeling in WinISD…got a couple questions

What wattage should I model when calculating cone excursion? Should I do the maximum amplifier output (keeping within the RMS rating of the sub), or a percentage of that?

Does my curve on the cone excursion graph need to stay below Xmax fully? Even when I add a highpass filter most of my models still have the driver go past Xmax between 10-15Hz.

I've searched for answers for maximum port velocity and have seen answers all over the place, lol. What say you?

What do I want the Transfer magnitude function graph to look like. I've read a few posts on what it is suppose to represent but I still don't quite understand.

Thanks

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post #2 of 3 Old 11-29-2018, 09:29 PM
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Originally Posted by TStubb View Post
Hey guys,

I'm learning the basics of sub design and am doing some modeling in WinISD…got a couple questions

1)What wattage should I model when calculating cone excursion? Should I do the maximum amplifier output (keeping within the RMS rating of the sub), or a percentage of that?

2)Does my curve on the cone excursion graph need to stay below Xmax fully? Even when I add a highpass filter most of my models still have the driver go past Xmax between 10-15Hz.

3)I've searched for answers for maximum port velocity and have seen answers all over the place, lol. What say you?

4)What do I want the Transfer magnitude function graph to look like. I've read a few posts on what it is suppose to represent but I still don't quite understand.

Thanks
1) Me personally I look at a wide range when looking at this. When trying to decide on a sub driver I keep them all the same, 1 watt/1000watt. When coming up with an enclosure I'll look at the maximum wattage I can run with the planned amp, what wattage gets me to my goal and what additional wattage would get me.


2) Xmax isn't Xmec, but most Xmax is slated for usable excursion, it is a good idea to stay below this although in a few exceptions you are fine going beyond this point as long as you don't reach the mechanical limit of the speakers excursion(IE Bottom out the driver). The lower you go the more excursion will occur.


3) I've kept mine below 25 m/s, if I get above this for peak then I can live with that for movies, for music that's different. The higher the port velocity the more compression you will get from the port.


4) I'd read up more Transfer Magnitude Function, this one is a bit tough for me to explain.
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post #3 of 3 Old 12-01-2018, 12:45 PM
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Quote:
Originally Posted by TStubb View Post
Hey guys,
What do I want the Transfer magnitude function graph to look like. I've read a few posts on what it is suppose to represent but I still don't quite understand.

Thanks
@Trimlock gave you good answers.

For transfer function, simple answer is it is the output vs. the input. Basically, this graph shows the frequency response.

As for what to look for, there is no set answer. What is your goal? Do you want a smooth, gradual rolloff at the low end like sealed? Or do you want to go as low as posssible with a flat response, and then when you go below tuning the low end drops off like a rock? Then you want ported.

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