In my opinion it’s not needed when Linkwitz Transform can be applied to sealed boxes.
Like the etchings of Escher, it is possible to express non-sensical thoughts in highly technical-sounding language.
Yes, if my car radio had the same transfer function as a Klipschorn... and so on.
B.
That's a rather blunt reply.
There are reasons why someone would prefer a vented box over a closed box.
That totally depends on the context, size, budget, looks parts etc
So in fact it is a thought that makes a lot of sense, but maybe just doesn't apply to your particular situation.
It was just a response to the statement to NEVER put a vent in a box.
A well designed ported box can also perform very well.
I know I would always use a vented box of some design. And actually experimenting with different stuff.
Agreed, if you want to add all that unnecessary EQ.
The most that I would want for a LF HP system response is third order. A ported box is fourth, so you would need to add in a 6 dB/oct rise at the low end, thus exacerbating the "below resonance" port problem. To me a 2nd order closed box - or several actually - is just right as it has the lowest LF phase shift.
If you are really worried about cone excursion (I am not) then use a first order HP to a closed box.
Dr Geddes,
I use active LR24 crossover between my dipole subs and dipole mains.
The mains have additionally a dipole peak notch filter.
The subs have a gain/rolloff compensation applied.
All XO/EQ are active analogue electronics.
Is the bass of my system acceptably in line with the mains ?
TIA for your reply.
I use active LR24 crossover between my dipole subs and dipole mains.
The mains have additionally a dipole peak notch filter.
The subs have a gain/rolloff compensation applied.
All XO/EQ are active analogue electronics.
Is the bass of my system acceptably in line with the mains ?
TIA for your reply.
I don't use a HP filter between my subs and mains. One reason is the large phase shift that this causes. But in the end if the amplitude response is smooth then the phase should be OK.
No HP filter on the mains? Doesn't that put the mains driver at risk of being over-driven or otherwise muddied with low bass?
B.
My mains are 15" drivers in closed boxes - for high DI - so there is not much danger of of them being overdriven. I add subs at the low end to smooth the response not to take the load off the mains. With your dipoles that would likely be an issue - a good reason not to use dipoles.
Granted a coherent concept, but reasonable people may differ as to whether a 15-inch driver in a largish box makes an optimal mid-range.
Maybe not a big issue for ESL dipoles which are always bi-amped and otherwise not bothered, but true enough issue for cone dipoles, looking only at that single consideration.
B.
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My data supports my contention so "reasonable people" should accept that as evidence.
My mids are 10" and I thought that was big. I put a HPF on them as they sound better that way. They lose that tinge of nasality when they don't have to work on the lows. And they go down to 30-40 Hz without the filter. As for the phase shift the LR24dB XO is phase friendly but indeed not linear. However when I compare the LR with linear filters generated by DEQX, honestly I cannot hear any difference in the lows. The group delays acceptance thresholdis thought to be 2 cycles, in case of the lows that would be 20-30 miliseconds. My subs are high quality 10" drivers, two per side.They have also LR24dB (LPF) at the xo frequency with the mids.
The subs all use a simple 1st order LP, but each happens at a different frequency. Once again, if the system is EQ'd to smooth then the phase will have to be smooth as well.
I continue to believe that crossover slopes should be a low as possible for the intended response. The HP on my compression drivers is 1st order - way up at about 8 kHz though (even though the driver handles down to about 800 Hz.) The woofer LP is 3rd order, but nothing even close to being of a fixed design like LR24 or Bessel or whatever.
As to using fixed filters, its the acoustic response that matters and the electrical requirements will virtually never be one of these pre-designed filters.
As to using fixed filters, its the acoustic response that matters and the electrical requirements will virtually never be one of these pre-designed filters.
I'm inclined to think you've found and treated an important issue, but drawn the wrong conclusion for its cause.