Another Enclosure Question

[BEAVER]

I think I've finally figured out WinISD.

I do, however, have a question...

After plotting the largest box I can fit (1.2cft. @ 28hz) I get a nice flat response, BUT it's dropped 3dB by 33hz. Is this ok/normal?

I've seen graphs posted here from other members that show a flat response to well below this point.

Is this is good as it's gonna get? Should I be doing something different? ...Or looking at a different driver?

I must also say that I plotted the same driver in a sealed enclosure and this does beat that by a pretty good margin.

I would have posted the graph, but can't figure out how. :confused:

[a$$hole]

Read this and then make your choice :D

http://diyaudiocorner.tripod.com/dilemma.htm

[BEAVER]

Are you a teacher? Another reading assignment? :)

Thanks. I know you are trying to help... and you have, whether I like to admit it, or not.

[Eric Stevens]

I think I've finally figured out WinISD.

I do, however, have a question...

After plotting the largest box I can fit (1.2cft. @ 28hz) I get a nice flat response, BUT it's dropped 3dB by 33hz. Is this ok/normal?

I've seen graphs posted here from other members that show a flat response to well below this point.

Is this is good as it's gonna get? Should I be doing something different? ...Or looking at a different driver?

I must also say that I plotted the same driver in a sealed enclosure and this does beat that by a pretty good margin.

I would have posted the graph, but can't figure out how. :confused:


The predicted response in WinISD is a guide only!!!!!!!!!

When you install your enclosure in your other enclosure (your car) everything changes dramatically.

For example a sealed subwoofer system that models as -3dB at over 80 Hz half space is then put in a mid size sedan (Mercury Sable) and then measured, it is -3dB at well below 10Hz relative to energy at 80Hz and is more than 9dB higher at 20Hz than at 80Hz with a very smooth overall response.

The lowest -3dB point is meaningless in the car environment. What is it going to do in the car is much more meaningful. Problem is you need something like LEAP to even predict it and even then it is not so accurate.

Eric
Image Dynamics

[a$$hole]

Eric , you killjoy :D

Please don't try to argue with what Eric said, "That sums it up" !!

Love the fact you take the time to peruse DIYMA ! Thanx Eric :)

[BEAVER]

I guess I need not worry, then.

Thanks for the insight.

[Eric Stevens]

I guess I need not worry, then.

Thanks for the insight.

Well to add some more insight to the transfer function issue that happens when putting one enclosure inside another.

The more static displacement relative to the larger enclosures volume the more gain that will be realized. So the model for a single 10" verses a pair of 15" will be very different. For a single 10" sub you want a -3dB point in an average sized car in the low to mid 40Hz range typically and as you have more static displacement your can bring that up.

The other factor is what kind sound are you after and what is your listening style.

To add more confusion, where the enclosure is in the vehicle can change things dramatically. Just like in a listening room in you home you want the subwoofer system at the boundary of the room, like a corner.

This is why so many people fire the subs rearward it corner loads it but with loss of upper end impact and detail. I prefer to fire forward up through the rear deck or thru the rear seat and seal off the trunk from the passenger compartment making that the boundary of the room so to speak.

Eric
Image Dynamics