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Improving on centre channel with anti-phase centre
Okay what I’ve done is sent centre from the main AVR decoder to the Yamaha DRP-100 seen in the diagram. The centre invent is helped from the left and right from the main AVR decoder.
The role of the task is to get a signal sent to the Yamaha DSR-70Pro Dolby pro-logic to place an anti-phase signal to cannel or reduce the amount of signal on the (centre main signal) which shouldn’t be on the (main centre channel of ‘2010’).
There is downside since the signal will reduce some portions of the signal and (will inject a signal from centre phantom left and right). If there is signal of similar sound / frequency or mirror image it will be cancelled out thus freeing the centre front by a small degree.
The test signal I used was the dts calibration music and demonstration set-up disc (track 14, all-channels) which is a wideband pink noise signal.
I activate the Yamaha DRS-70Pro which sends out the same pink noise that is being sent to left and right front. I then adjust the centre level on the Yamaha DRS-70Pro so that the pink noise will cancel out the centre. Its only reduced (all or part of the lows) mid and highs are reduced down to very faint sound. Reason is the Yamaha DRS-70Pro has limited bandwidth down to 100Hz so tiny bit low end is heard but its reduced most of the directional.
Now before most of you start jumping around up and down, this doesn’t wreak the sound no worse than it already is. This helps by reducing the centre main will still perform most of its original level.
There it is, simple. I guess this can be improved upon with fancier audio electronics.
This can also remove normal half panned sounds from the centre for clearer left and right stereo sound field. Often the phase tends to have you shifting around in the sofa to catch a clearer left and right sound.
I tired this out a few years ago, with ‘Beverly Hills Cop’ (1984) when Foley gets tossed out a window and then cops show-up. There’s subtle effects left and right that had half panned sound filed mixed onto the centre and I found it distracting at the time.
Today I place a little delay on the DCX2496 centre LF/HF to gain a clearer left and right sound filed, or I can extend it further with the approach that I have just shown you.
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Notarize speech bleed though on you’re sub
Most of you may hear a little voice speech seeping though the sub on a few occasions. It’s mostly around the 100Hz to 200Hz range that manages to get though.
Okay, then since the way I run the sound system here is a little different with the low end from LCRS sent from various processors from the main AVR so I can cheat or find away around of controlling the low end thou the 6channel audio mixer.
The Eltax A-12R crossover high pass filter always lets a little audio low end speech (sound as an audible muffled tone).
Okay, so how did I solve this? Answer used a few filters on the BFQ2496 and placed sharp cuts of -36db and a little Q to kept most of the male speech that often goes down to 100Hz while monitoring on the RTA.
So that is it simple fast and it will kinder relax the energy on the subs amp by a few db where some tones are not need, they are however need over the LCR or surround depending on some crazy dialogue panning that moves around all-5 channels.
Anyhow you don’t have to set you’re BFQ2496 or DSP1124 to these frequencies its what I used to make it work here after trail and error of listening to the same moment from Bluray “Star Trek The Motion Picture” chapter 12, thou it doesn’t have to be this title or this chapter!
I also tested the sub bass extension with crossover THX set ON which is around -24db down at the crossover if I’m not too mistaken. The AVR still allows a tiny hint of voice dialogue to filtering though it, (only a tiny hint)!
With the THX crossover 80Hz turned off as it always since I run an DCX2496 for the LCR and the surrounds have there own amp and bass treble and EQ control my sound system won’t sweat it. So back to the normal way of running and with the (bypass mode turned back to ON the BFQ2496 its like having an extra filter, brick wall, placed right in front where the voices filter though.
The subs high pass crossover must be very shallow, I doubt 24db more like 12db. Well now I have an extra 180Hz -36db 302Hz -36db 502Hz -36db to deal with it.
Its all, trail and error!
The graph below only shows a prediction of what it should look like.