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Discussion Starter #1
I have two questions around the CSS SDX 15 driver

1. how do you know when you do or don't need a highpass filter to keep the sub from bottoming out?

Example:
Two tunings 16Hz and 12 Hz. Is either of these going to be reasonably safe without a filter? Both? Why?



2. How does the lower tuning affect the sound of the sub? A slight 'softening' of low frequency response? To me, the curve at 12Hz starts to look like a sealed sub. Would I be looking at equalizing to flatten low end response? There probably isn't a good answer to the last question because my room response affects the sub's response but hey, I can ask. :bigsmile:



I am thinking yet again that the best thing I could do for myself is to pick up a 24" tube that gives me enough volume for my largest possible design and then build an adjustable top and port and experiment in room.
 

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1. how do you know when you do or don't need a highpass filter to keep the sub from bottoming out?
That depends on the box volume, tuning frequency and power input. Modeling the sub will show at what point the sub exceeds Xmax within these variables.

2. How does the lower tuning affect the sound of the sub?
The lower the tuning the more low end extension at the expense of overall output. It's a trade off.

Would I be looking at equalizing to flatten low end response?
That depends on the subs interaction with the room. Using REW will show you exactly how your sub is performing and where any equalization is required.
 

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I would say no to question #1, but it depends upon a bunch of variables like Mike has already stated. The potential is there for serious damage if a 10hz signal ever got into the SW at the intensity you've shown in that first graph with either SW. It may not ever happen, but it could.

The 12hz design looks undersized. You could make the enclosure volume larger than the 16hz design to get the FR to look more comparable to the 16hz design, but deeper extending if that's an option. Room gain would probably boost up the 12hz model nicely though.
 

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Discussion Starter #5
OK. Both plots are at 1000w, the maximum the driver can handle. I don't have access to winisd here, but I think that puts the volume up to around 120db. Hmm. What is the likelyhood of getting somthing at 10-12Hz at full bore...
 

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If you are watching a movie loud enough to cause 115-120db peaks it is quite possible to get a signal like that. Actually you could reduce the power down to probably 300w and 110db peaks and still be in danger of damaging the driver below tune. You just don't want to operate a vented cab wide open below tuning if you can help it.
 
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