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Re: 2xT45's & 2xOT12's - And your time starts... Now
Posted: Tue May 22, 2018 6:05 am
by AKC1
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!
Thank you
Alex
Re: 2xT45's & 2xOT12's - And your time starts... Now
Posted: Tue May 22, 2018 6:21 am
by CoronaOperator
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.
Re: 2xT45's & 2xOT12's - And your time starts... Now
Posted: Tue May 22, 2018 7:54 am
by AKC1
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..
Alex
Re: 2xT45's & 2xOT12's - And your time starts... Now
Posted: Tue May 22, 2018 10:14 am
by AKC1
I will basically be tuning as per this article (See page 2 and on)
https://www.prosoundweb.com/channels/av ... s_in_sync/ except I will be using RTA to make results more accurate.
Set EQ per driver then adjust phase to match.
Alex
Re: 2xT45's & 2xOT12's - And your time starts... Now
Posted: Wed May 23, 2018 2:46 am
by Grant Bunter
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...
Re: 2xT45's & 2xOT12's - And your time starts... Now
Posted: Wed May 23, 2018 4:03 am
by AKC1
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...
Definitely
Re: 2xT45's & 2xOT12's - And your time starts... Now
Posted: Wed May 23, 2018 7:07 am
by Bill Fitzmaurice
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.
Re: 2xT45's & 2xOT12's - And your time starts... Now
Posted: Fri May 25, 2018 11:11 am
by AKC1
Just keep cutting, Just keep cutting...
Meanwhile been thinking up a colour scheme, what are your thoughts??
Re: 2xT45's & 2xOT12's - And your time starts... Now
Posted: Fri May 25, 2018 7:21 pm
by bitSmasher
Been looking at Pure Groove systems, for the colour inspiration?
Re: 2xT45's & 2xOT12's - And your time starts... Now
Posted: Sat May 26, 2018 12:07 am
by Tom Smit
Meanwhile been thinking up a colour scheme, what are your thoughts??
Cool.
Re: 2xT45's & 2xOT12's - And your time starts... Now
Posted: Sat May 26, 2018 5:05 am
by AKC1
bitSmasher wrote: ↑Fri May 25, 2018 7:21 pm
Been looking at Pure Groove systems, for the colour inspiration?
Have never heard of them, will see what Google has to say
Re: 2xT45's & 2xOT12's - And your time starts... Now
Posted: Sat May 26, 2018 5:17 am
by AKC1
See what you mean about Pure Groove. Those are good looking speakers!
- Danley-PG-Series-2016-02.png (127.1 KiB) Viewed 1665 times
Bill, I noticed they do a synergy horn. Is that style of speaker a Danley patent or in theory could you design us a nice one for us all to build?
Alex
Re: 2xT45's & 2xOT12's - And your time starts... Now
Posted: Sat May 26, 2018 8:29 am
by Bill Fitzmaurice
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.
Re: 2xT45's & 2xOT12's - And your time starts... Now
Posted: Tue May 29, 2018 6:05 am
by AKC1
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.
Re: 2xT45's & 2xOT12's - And your time starts... Now
Posted: Tue May 29, 2018 10:44 am
by 88h88
Considering how many drivers those things use I'd not look forward to moving them about. A top as big as the subs? Amazing.