Passive way to maximize Dayton ND91 3.5" full range bass?

I'm going to be using the Dayton ND91 3.5" 4ohm speaker in a portable bluetooth setup.

Dayton Audio ND91-4 3-1/2" Aluminum Cone Full-Range Driver 4 Ohm

Since I want as small as possible an enclosure, I've decided to go with PartsExpress' recommended .01 cu.ft. sealed enclosure.
Now, when I model this in WinISD using 33 watts (about what I have available), I have tons of room left over before hitting the rated 4.6mm x-max "limit".
So I'm thinking I'd like to tweak it just a bit for a bit more bass down below.

You can see in my screenshot the first two WinISD pictures are without any bass-boost.
The third is with 3db added to 80hz.
Some quick Googling shows you cannot passively add "bass boost".
But you CAN attenuate, say, all the frequencies above 80hz.

So, I'm hoping someone can suggest what to do next to get what I want?

I also added the WinISD file in case anyone wants to model on their own.


  • Dayton Audio ND91-4 3-1_2_ Aluminum Cone Full-Range Driver 4
    916 bytes · Views: 60
  • nd91.jpg
    485.7 KB · Views: 437


Paid Member
2005-08-16 4:21 pm
depending upon circumstances, you might be able to get a bit more with a series capacitor - when doable, that will alter system impedance around resonance, lowering Z with more power into the speaker and more excursion in that area. (this may not work with low feedback tube amps)
Sealed you can run it in 2 litres..... erm.... 8x4x4 inches internal dimensions down to about 100-105hz. A bigger box gets you more bass down to say 85hz in 6 litres.

Vented you need 6 litres but it can be tuned for bass to 50hz.

I ran it through WinISD. Grabbed the driver "WDR" file from this forum.
Incidentally, you could get the newer WinISD?
WinISD - Linearteam

Last edited:
Thanks, folks.
I did not realize a newer WinISD was out.
I'm on 0.50 and the link above shows an 0.7xxxx available. I'll check it out!

I'm building a vented 0.30 cubic foot enclosure tuned to 75hz.
Should be done by tomorrow. :)
Here it is modeled vs. the same size 0.30 sealed enclosure.
Added a high pass to the vented. Sealed didn't get one.

It's looking like I won't need any passive attenuation. :)


  • Untitled.jpg
    447.1 KB · Views: 407