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Author Topic: Downmixing on CP650 Tim OBrien Film Handler Posts: 36 From: Vassar, MI /USA Registered: Jan 2010 posted 01-25-2013 04:41 PM                        Ahh, the light is on now! All of this makes good sense. I had planned to run the sub straight through but Manny's suggestion will provide for a convenient control point. An 8-4 mixer will do nicely and provide and extra output for a possible center speaker. Thanks, everyone, for the education!  |  IP: Logged Carsten Kurz Film God Posts: 4340 From: Cologne, NRW, Germany Registered: Aug 2009 posted 01-25-2013 06:35 PM                     Actual '8to4 Mixers' are a rare species. You will usually find it among to more expensive xto4to2 or xto8to2 mixers with so called subgroups. However, some smaller mixers have a feature called ALT 3-4. These have a switch for each channel which can be used to route it to either the master fader/stereo out, OR an alternative 3/4 output. One example is the Mackie 802-VLZ3 at around 200US$. You can also get it very cheap second hand at ebay: http://www.ebay.com/itm/Mackie-802-VLZ3-8-channel-Stereo-mixer-/271143575422?pt=US_Live_Studio_Mixers&hash=item3f216 a9f7e&_uhb=1 Another option would be the Behringer 1204 in either the plain (second hand), FX or USB variant. It does not have enough mono input channels for a 5.1 mixdown, but you can easily use two stereo channels for L/R and Ls/Rs, and the mono inputs for C and LFE. So L/R and Ls/Rs going to the Master L/R output, while C going to ALT-3 and LFE going to ALT-4. 2 Stereo amps and you're set. If you don't have an actual subwoofer, but your L/R speakers have enough bottom, you can just route LFE from the CP650 to both L/R, not using the ALT 3-4 switch for LFE. - Carsten  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 01-25-2013 07:50 PM                     Here is something that will do the mixdown in 1U of space and is made in USA http://www.rane.com/sm26s.html  |  IP: Logged Carsten Kurz Film God Posts: 4340 From: Cologne, NRW, Germany Registered: Aug 2009 posted 01-25-2013 08:44 PM                     Costs two to three times as much as the Mackie 802, with the missing functionality of separate C/LFE routing, tone control, headphone monitoring, Mic In, VU meters. - Carsten  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 01-26-2013 07:05 AM                     To each their own, I guess. Note, the routing capabilities of the SM26 are better than you are giving it credit for, between the master in, mono-ins, master out, direct outs and the mode headers, the thing can be set to be in just about any configuration needed...including whatever you want to do with the center/LFE. It also all fits in 1U of rack space.  |  IP: Logged Antti Nayha Master Film Handler Posts: 268 From: Helsinki, Finland Registered: Oct 2008 posted 08-06-2013 12:26 PM                     So what's the Film-Tech Experts Board's consensus on the best way of downmixing 4.0 matrixed audio (Dolby A/SR or LtRt video source) to a 2.0 or a 3.0 outdoor setup? The three front channels are obvious and were already discussed, but should the mono surround output go: 1) to C channel only (surely not?) 2) to L and R channels equally 3) to L, C and R channels equally 4) nowhere? I would lean towards option 2, but it'd be nice to hear your opinions. Also, would you mix the surround channel to the front speaker(s) at full volume, or at let's say 50%?  |  IP: Logged Carsten Kurz Film God Posts: 4340 From: Cologne, NRW, Germany Registered: Aug 2009 posted 08-07-2013 06:20 PM                     I guess I would choose L+R. I - Carsten  |  IP: Logged Manny Knowles "What are these things and WHY are they BLUE???" Posts: 4247 From: Bloomington, IN, USA Registered: Feb 2002 posted 08-07-2013 09:24 PM                     Option 2  |  IP: Logged Scott Norwood Film God Posts: 8146 From: Boston, MA. USA (1774.21 miles northeast of Dallas) Registered: Jun 99 posted 08-08-2013 07:42 AM                        I have done a number of screenings in temporary setups with L/C/R and no surrounds. In all cases, the surround channel information was just discarded completely. It sounded fine. I would be a bit wary of doing this with digital sound, where there is no leakage between the front channels and the surrounds, but it works fine for analog matrix decoding (although, admittedly, I am talking about art-house-y stuff...not Star Wars).  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 08-09-2013 10:58 AM                     We built a protype drivein interface and what we did was to the LT RT outputs we matrixed as follows L to +LT C to +.707LT +.707RT R to +RT LS to +.707LT -.707RT RS to +.707LT -.707RT SW to .707LT .707RT Then we put a limiter on it and also provided 2 mono outputs for field speakers and one for AM If i can ever find some time i will attempt to finish it off  |  IP: Logged

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