Still need assistance designing a midbass cab

[klampykixx]

i think i might have missed a key point on the QB5. to confirm, is that ported or sealed?

i thought it was sealed, but then re-read and think its ported?

my cabs are about 55L and have a 5mmx600mm port, 100mm long.

can you please assess as to wether or not you feel this is even close to the "ideal"

i got the specs off bassbox pro for this cab. its tuned to 80-100hz.

[rcw666]

The QB5 is indeed ported and if you have a q=.5 high pass filter at about 140 Hz. on them then they are about as close to a QB5 II box as you really need.
rcw

[klampykixx]

so basically youre telling me, that my active XO i just bought should be more than satisfactory as far as running the deltas to their absolutely peak potential as long as filtered to the right frequency?

i dont understand what the Q=0.5 means, is that to do with the filter slope?

[rcw666]

A q=.5 second order filter is an L-R one, most electronic crossovers have L-R filters in them, if the filter is a Butterworth with a q=.707, then the frequency should be increased to about 160Hz.
rcw

[klampykixx]

Professional stereo 2-way/mono 3-way crossover featuring state-of-the-art Linkwitz-Riley filters with 24 dB/octave

question answered.

is kinda nice to know i was on the right track all along. just ended up going around the block before coming to the driveway i passed twice already...

[rcw666]

A very instructive thing to do is to play a test tone at a particular level, measuring it with a microphone, then run the system at the level you usually use for about 5-10minutes.

Then with the same settings as you used in the first measurement measure the test tone.

The difference in level is power compression.

Many people who have bought the power hype, discover that after running for this long there system is 6-7db. less loud than it was when cold, and no further power input will make it any louder, many try of course and speaker re coning people make a good living from it.

If you back off the output in the first place then after 5-10 minutes measure again and if the level has gone down by 2db.this is what you want, the drivers are under much less stress and typically the output will be a few decibels more because the voice coils are running cooler.

Try telling a power junky that if they put less power into there system it will play louder and see what reaction you get, but if you try it you will find that it is true, and your drivers will last longer and be more reliable.
rcw

[klampykixx]

im not one to constantly push and push my system louder and louder, when i do my sound check, i try to get it to where i think its as loud as its going to get and then set that as my absolute max knowing that altho its running hard, its not at the "limit" so still has an amount of headroom for spikes and also room for me to tweak it up when mixing.

in the near future i think i will get the opportunity to do some testing, so if and when that happens, ill post results.

[klampykixx]

Originally Posted by col

If I get time I will do some live testing in the yard next week and will post some comparisons.

Setting the filter won't be a problem MiniDSP is great for this kind of thing.




Edit: comparisons between QB5 II and a 50L "optimum" BR.

any news on this yet?

[col]

Was flat out all week and didn't get any time. Will see how I go this week.

[klampykixx]

Cool.no worries at all. i would actually like to know if there is a comparison between sealed,br,and horn for top/mid on this forum? I found a comparison for a bass cab but thats all i could find. Anyone got a link to such a comparo?