WinISD - Cone Excursion

[Mutley666]

Firstly, please forgive me if this is a bit of a dumb question, as I'm fairly new to the realm of building subs.

I have been playing around with some subwoofer ideas in WinISD, and noted that the graph for the cone excursion show most subwoofers reach x-max at a very low watt input.

It is even worse if you add a Linkwitz Transform Circuit.

For example I have modelled the Eminence Kappa 18 in a 478 Litre Ported Enclosure, and WinISD shows the driver exeeding Xmax at 20Hz with just a 10Watt input.

The same drive in a 150 litre sealed enclosure with a LT circuit, and WinISD shows this exeeds xmax at 30Hz with only a 5Watt input.

I have modelled a number of other high excursion drivers as well and WinISD shows them hitting xmax well below their rated power handling and in most cases a minimal input!

Is this right? And if so how does this affect the driver and the quality of the sound output

[richie00boy]

It is right providing you have filled out the driver parameters correctly.

In the first case I reckon you are hitting Xmax with small power because you are looking well below the tuning frequency so the cone is basically unloaded.

In the second case your 5 watts will probably be taking the gain of the LT into account. Try modelling without the LT to see the true excursion limited power.

Welcome to the world of understanding why power ratings should not be taken at face value and why you must optimise your box

[Rademakers]

First of all some versions of WinISD give the cone excursion in peak-peak. So that's double the excursion as you actually have to consider. Look at the Tab of Maximum Power as well to be sure it's not p-p

Second of all Eminence has quite some drivers with a powerdip in a normally tuned basreflex cab. The Kappa 18 is even wurse then normal. In general Eminence is well known to have powerdip-drivers.
The Powerdip of the Eminence drivers is partially due to the relatively high powerhandling they got after they all got Kapton voicecoil formers. But partially it's also the overall design and the lack of Xmax in most cases.

On the bright side: Eminence is one of the fewe brands that isn't lying about Xmax AFAIK. Most other brands do.

Mvg Johan

[simon5]

I modeled your Kappa 18 and if you tune it at 20 Hz, you can give about 35 Watts before max excursion, in WinISD Pro.

Rademakers, why removing the LT to model it? The LT will limit the power imput to 5 watts anyway...

[richie00boy]

I said remove the LT not Rademakers My reasoning was that he will then see what the driver will really handle. True, this is exactly the same power as what will actually be coming out of the amp after the LT, but it can help put perspective on things in a 'raw' way if you can't quite get your head round what the LT is doing.

[simon5]

Hehe sorry Rademakers.

Thanks for the clarification richie00boy.

[Mutley666]

Things are never easy are they!

I have now purchased a Infinity Kappa Perfect 10 VQ (VQ stands for variable Q), as it was going for a song and has a 16.7mm xmax.

I think I'm gonna put it in a very small sealed enclosure (about 26ltr) and use a LT around 25hz.

I would I deally like something with a lot more punch, but the wife won't let me create a monster box!

It plots OK in WinISD but has anyone heard one of these woofers in action?

[Rademakers]

Rademakers, why removing the LT to model it? The LT will limit the power imput to 5 watts anyway...

I don't recall saying something should be removed, but ehhrr...what on earth Linkwitz Transform has to do with what I said?

Mvg Johan

[simon5]

You obviously didn't read richie00boy post right after that one and my post right after the richie00boy post hehe.

I wanted to quote richie00boy but I quoted you, I'm sorry.

[mike.e]

Originally posted by Mutley666
Things are never easy are they!

I have now purchased a Infinity Kappa Perfect 10 VQ (VQ stands for variable Q), as it was going for a song and has a 16.7mm xmax.

I think I'm gonna put it in a very small sealed enclosure (about 26ltr) and use a LT around 25hz.

I would I deally like something with a lot more punch, but the wife won't let me create a monster box!

It plots OK in WinISD but has anyone heard one of these woofers in action?

Ive heard an infinity kappa pro 10" in a car,clean output but the car ruins the sound



Also consider,below driver Fs the speaker is compliance controlled,which isnt linear,and distortion will soar below here.

regarding LTs,~12dB of EQ at 20hz on a sealed box just wont give me what i want...For some you have to -WAF and all that,but its not ideal