Want to try out Cap Assist Sealed Box. Also trying out VCAD’s enclosure design. Based on what i entered, it seems to work, but i may have not entered or done everythign right.
The cap assisted box is turning out to be 20 lits with an F3 of 49 with a cap of 750uF.
for a Q of 1, unibox and VCAD doesn;t seem to agree. The F3 is close, but unibox says 10 litres and 68F3 , and VCAD says 18 liters and 63F3. The lower F3 makes sense for the larger box, but not sure why the size would be so different for Q of 1.
At the usual sealed box (no cap assist) both Unibox and VCAD seems to agree on the F3 and Box volume (very close). that would be around 30 liters sealed with F3 of 55.
Vented is 32hz F3 but needs a 2cu ft box. Both sealed and vented seems to work, but the cap assist seems best for 2/3 of the box size of sealed and 5Hz lower tuning.
This is what I entered in VCAD - it seems to assume or calculate a bunch of things, not sure which ones we need to tweak - tried to entere what I typically put in Unibox - these are highlighted. If there are other parameters that I need to enter rather than VCAD assume or calcuate, please let me know.
I compared with dats and highlited the otehr fileds which DATS provided in Blue - the values are close. These seem to be calculated rather than measured - but should i enter some or all of these too in VCAD?
I have used cap assist closed box for one finished design, a 3 way with a RS270 woofer.
Worked great, I have recently played with cap assist for several 12 inch woofers.
Couple of points, driver Qts should be a bit high. The Rival 8 inch at .52 Qts looks about right, So model it in a closed box that is too small, so a 2 dB bump is produced. The cap will flatten this down and extend F3 and F6.
Finally, I noticed that I got a different result when measuring the woofer without a crossover. When tweaking, get the woofer LP crossover pretty close before you add the cap assist before the LP. Yeah, pull some 100-150 NPEs out, IME, not real hard to find the optimum value. Too much or too little uF will roll off the low end, Keep us posted!
