Grant Bunter wrote: ↑Tue May 22, 2018 4:24 am
My thoughts:
Phase is frequency dependent. Therefore, the only delay you can add is at a crossover point (subs to tops), so you can then check phase response (unless you want to go to FIR filtering).
Subs and tops need to be in phase at the crossover point. Mids and HF need to be in phase at their crossover point.
Personally I think it's almost redundant to setup delay for drivers in tops (ie between mid and HF) because there will be about 1 maybe 2msec in that setting and we simply can't tell that small a difference when applied. By all means play with it though.
I would be more inclined to save a 7 band PEQ (left on your flow chart) for subs and tops as a system save, and tweak it at each venue.
This is what I do, but with GEQ.
Mirror imaging an SPL chart is a great way to get a start point for EQ...
Ahh, i see what you are saying and noted. I will either be using 24db/o or 48db/o slopes, these have a symmetrical phase distortion at crossover frequency of 180 and 360 respectively so will sum perfectly in phase and magnitude at the crossover frequency. The distance between the the acoustic centres on a OT12 looks to be about 15cm. At 1200Hz crossover frecuency (a wavelength of 28.59cm @20degC) this puts the signals at 180deg out of phase, so I believe the OT12's drivers definitely need delay and phase alignment.
I will try try things both ways and report back, I have no problem with being wrong and learning from mistakes!
AKC1 wrote: ↑Tue May 22, 2018 6:05 am
these have a symmetrical phase distortion at crossover frequency of 180 and 360 respectively so will sum perfectly in phase and magnitude at the crossover frequency.
Maybe in the electrical world, but in the physical acoustical world your drivers and their enclosure alters the phase response and the magnitude response - sometimes drastically. Once that electrical signal goes to your voice coils and gets converted into motion, everything changes. Until you measure, you won't know how the acoustic phase and magnitude response will look like at the crossover frequency for each of the drivers.
CoronaOperator wrote: ↑Tue May 22, 2018 6:21 am
Maybe in the electrical world, but in the physical acoustical world your drivers and their enclosure alters the phase response and the magnitude response - sometimes drastically. Once that electrical signal goes to your voice coils and gets converted into motion, everything changes. Until you measure, you won't know how the acoustic phase and magnitude response will look like at the crossover frequency for each of the drivers.
Hi,
Very true which is why I wanted the ability to EQ and adjust delay/phase for the individual drivers. I plan to set these using measured RTA phase and magnitude not guessed values so fingers crossed the end result should be good.
So nice to be able to discuss this with people, most people I talk to just look blankly when discussing anything other than frequency response. You guys rock..
Tell us how it goes.
If it drives you nuts in the end, build the internal passive filters for the tops, which does what you want to try to achieve via DSP.
Remember, the passive filters are custom for Bill's designs, and address the issues of phase.
And negate the need to bi amp...
Built:
DR 250: x 2 melded array, 2x CD horn, March 2012 plans.
T39's: 4 x 20" KL3010LF , 2 x 28" 3012LF.
WH8: x 6 with melded array wired series/parallel. Bunter's Audio and Lighting "like"s would be most appreciated...
Grant Bunter wrote: ↑Wed May 23, 2018 2:46 am
Tell us how it goes.
If it drives you nuts in the end, build the internal passive filters for the tops, which does what you want to try to achieve via DSP.
Remember, the passive filters are custom for Bill's designs, and address the issues of phase.
And negate the need to bi amp...
What really negates the need to bi-amp is the high sensitivity horn loaded woofer. Direct radiators need so much power that the amps driving them tend to get pushed too hard, with the resulting clipping creating at best high THD in the high frequency elements, at worst blown HF drivers. That doesn't happen with high sensitivity speakers, unless you decide to use a 20w amp.
The added complexity, amps and cabling of bi-amping isn't worth the bother with a system less than four times the size the OP proposes.
I've never had the urge to do a synergy horn, as most of its benefits are also in the OTop, Jack and DR designs. The synergy is different, but not better.
Bill Fitzmaurice wrote: ↑Sat May 26, 2018 8:29 am
I've never had the urge to do a synergy horn, as most of its benefits are also in the OTop, Jack and DR designs. The synergy is different, but not better.
True, i hadn't thought of it as they look so different.