[blackreplica]

Maybe it's just me but...

i've always felt tuning to between 30-40Hz is the way to go. any lower and you may have problems with group delay, but more importantly, who wants so much low end rumble? That kind of thing can really ruin most music IMO. I personally think that tuning no lower than about 3/4 octave below cabin resonance should be perfect. considering most cars resonate around 50-60Hz, tuning 30 -40Hz should suit most setups. Subsonic filters should be mandatory too of course. Winisd may recommend 25Hz for example, but thats 'maximally flat' optimisation which ignores vehicle transfer function. With ported box, its easy to get 'wrong' and i think most of the time this happens because people plonk an anechoic maximally flat box into the car, and the response just goes to hell once put in car.

But this is just MHO...

 

[blackreplica]

No problem dude. About group delay, my messing around with winisd has led me to the conclusion that higher tuning freq = lower group delay in ms. Maybe when i did it, it was a basket case. try messing with tuning freq on your own and see if it comes out the same.

People do recommend lower tuning as 'better' for group delay because you are much less likely to hear it at lower frequencies though. So its a tradeoff IMO between higher tuning and lower group delay in ms (provided i am right) but higher chance of audibility vs lower tuning and higher group delay in ms but lower chance of audibility. Either way i doubt group delay is a problem unless very very severe. It's the frequency response issues with low tuing which bother me more. Just MHO anyway