I previously had my 2 ID Max's in a 5.1 cu ft net ported enclosure at 27hz, which sounded great but i wanted more SQ hence I put them in a sealed 1.3cu ft box (each woofer, separate chamber) and have lightly placed dacron in the box (not stuffed).

I only finished it at around midnight last night and have been at work all day so haven't really done much troubleshooing but I was hoping you guys might have some insight into the problem. In the upper bass range it sounds like its hitting an empty bucket so to say or as if it is bottoming out.

I plan to run some sweeps when I get home to sus out the exact freq range where the problem exists

The box is solid as, fully sealed and I have double baffled the front 36mm

You help is very much appreciated!

where do you have your xovers set and how high do you want them to play?

I tended to find my IDMAX 12 was strongest up toa round 60hz or maybe 70hz as well. Low end control and detail was phenomenal. Couldn't fault it here.

However, I found it's top end for me above 70hz wasn't particularly impressive. Not by any means BAD, just could probably be better. Was runing in around 1.1 cubic feet sealed. From personal experience and the opinions of others who have used them, it appears to me the IDMAX defiantely works best when crossed over low.

This was all fine for me though, as I prefer to run low cross over settings, and so the IDMAX worked perfectly for me

I usually have my Boston mids crossed down to 64hz 12db/octave and then overlapped the sub freq up to 80hz on an 18db slope. The boston mids dont seem to be able cope down to 64hz on their own hence I overlap the freq.

I have tried crossing the sub at 64hz which seems to help but then theres a hole in the mid bass.

Preliminary thoughts are that I should take out the dacron?

Any thoughts?

I probably wouldn't remove the dacron,
I'd actually probably look for a better dampener material,
A proper 10mm soft open cell foam lining will work better.
and smooth things out.

if your not happy with the Response, try using different overlaps from the midrange to the sub,

I've run setups ranging from 63hz 24/24 on both to 63hz 18db - 80hz 6db on the mid.

if you want the subwoofer to produce a Higher sound tonally, try working with a softer slope (6/12db),
if you want a deeper more thumpy sound then work with a harder slope (24db)

Removing the dampening from the box, could make it boomy, it will defiantly make it louder, but you may get a erratic freqency response.

be very careful with your crossovers not to cause your bass to play out of phase, if you get the wrong combo between mid and sub x/over the whole thing can get out of phase by up to 90deg.

also be careful with soft slopes on the sub, as your sub bass may become directional.
Don't let people tell you bass "isn't directional" Improperly setup subwoofers can be very directional, with the bass sounding like it's coming from the subs direction, rather than sounding like all the bass is together with you and your whole system.

Play with your Front stage, there is very very little difference between running 64hz 12db, and 80hz 12db, you might be able to get away with 80hz 6db. I always just try to take the "movement" out of my front stage, without removing the bass response, Just work with the speakers natural roll off, so you don't remove the sound it produces, just remove the additional movement caused by freqencys the speaker cannot play.

Juls

i actually LP my IDMAX quite high: 90Hz. i too use a sealed 1.3cuft box. and i HP my splits at 90Hz too. i find the sub reinforces the midbass really well, without any muddiness; just good clean kick.

i have also fairly heavily EQ'd the whole system, including the sub.

i suppose you just have to experiment. your car's acoustics could be coming into play.

This is why I think the solution is a little more than just adjusting the crossovers...

Regardless of the slope the Max's should be comfortable playing up to 100hz and do so effortlessly. I have just been been fiddling around and it seems that anything higher than 63hz 18db and it turns to crap. I don't mean "not so flash" but literally unbarable.

With this slope I played a variety of genres. Soft rock such as Crowded House and Evermore sounded awesome yet I put on some Crystal Method and it sounded awful... Really frustrating. And if I shifted that slope to 80hz, everything turns to crap.

Just out of interest Shiny and Muzzy do you use any type of dampening material in your box?

Speaking of acoustics playing a role i'll explain the set up maybe you'll have a diagnosis.

Car - VR Commodore (don't hold this against me as im really not a commodore person)

The subs are mounted above the rear axle (forget what its called) facing into the boot. The boot is completely blocked off from the cabin however I have cut a large section out of the parcel shelf for the bass to vent into the cabin. The entire boot is deadened bar the boot lid (to be deadened asap)

The sound it like I mentioned - a wooden spoon on an empty bucket, quite different to resonance

Try switching the polarity. Rear loading my also help.

Leigh

when ur mid's n sub's x-over frequency n slope is both 64Hz / -12dB, you have to switch ur sub's polarity as they would b running at 180degrees reverse phase at 64 Hz. That would fill the 'hole' u were talking about.

Sealed boxes tend to be boomy from 60-80Hz and often require EQ-ing. Rear loading also adds to this. As suggested, try changing the phase this often helps.

In sedans, mini-walling (sealing boot off from car and loading woofers through ski port) is usually the best option.

Rear loading means that the boot lid, boot floor and tail-lights play as much a part of how the woofer sounds as the woofer itself.....

Phil

Thanks heaps guys,

I think I might turn the box around and fire it into the cabin and hopefully this may help. Also thanks for the note on the polatity issue

minimal, and all in the name of reducing resonance. my box is part fibreglass, and i coated the inside of this with paint-on sound deadener. then i have stuffed in a SMALL amount of dacron; really just a layer on the bottom of the box, not filled it up in any way. i'd be surprised if what you've done impacts significantly on the problem, but you could always try removing some dacron to see.

None at all.

I had some internal fibreglassing but that's about all. No dacron or similar.