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Author Topic: Amplifier Hiss Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 11-06-2010 05:55 AM                        REmove snake from H. F. driver. Louis  |  IP: Logged Tony Bandiera Jr Film God Posts: 3067 From: Moreland Idaho Registered: Apr 2004 posted 11-08-2010 01:01 PM                     Good one Louis. Manny, the obvious answer is the DMA8 plus is bad..have it repaired or exchanged by Dolby. Like the CP-750s I had a problem with a while back...HERE I think Dolby got a bad lot of A/D or D/A converters recently.  |  IP: Logged Manny Knowles "What are these things and WHY are they BLUE???" Posts: 4247 From: Bloomington, IN, USA Registered: Feb 2002 posted 11-08-2010 02:27 PM                     Why the heck doesn't the DMA8 have a digital output???  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 11-08-2010 08:15 PM                     Because the DMA stands for Digital Media Adapter. Those that don't need Digital audio decoding, don't "need" it. You'll find that the vast majority of systems that use the DMA8 want it to have analog out.  |  IP: Logged Manny Knowles "What are these things and WHY are they BLUE???" Posts: 4247 From: Bloomington, IN, USA Registered: Feb 2002 posted 11-08-2010 08:31 PM                     Don't defend them, Steve! It's still a shortcoming -- or as they say, a "feature." A digital output would make the DMA that much more valuable, since it could then also be used as a switcher for those who have several digital sources, and only one digital input on their processor...  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 11-09-2010 08:05 AM                     It is not a matter of defending...it is a matter of fact! The DMA8's purpose is to give legacy products a means to play digital media. As such, there would have been little value to having a digital out. Now there may be a growing desire to have a digital out processor as "legacy" products turn into "obsolete" products. Personally, before I would worry about digital out, I'd like it if it also De-embedded audio from HD/SDI streams too. The original DMA8 had that option for SD-SDI...the Plus does not. Ultimately, for the foreseeable future, one has to get audio into analog to finish the job. It is much more recently than the DMA8 that processors have digital audio inputs...and most only have one, for cinema, and it is taken up by the DCinema system. Steve  |  IP: Logged Manny Knowles "What are these things and WHY are they BLUE???" Posts: 4247 From: Bloomington, IN, USA Registered: Feb 2002 posted 11-09-2010 06:48 PM                     Our setup and test screenings went well today and it looks like we're really gonna show a movie here tomorrow and Thursday. The 4K audio connects via the digital input so there won't be any of this noise at all for the super-important show. For Thursday, we'll just wait until the movie actually hits the screen before selecting Format 11. Once these "preview" screenings are safely behind us, we can look more closely at gain structure. Stay tuned!  |  IP: Logged Tony Bandiera Jr Film God Posts: 3067 From: Moreland Idaho Registered: Apr 2004 posted 11-14-2010 11:22 PM                     So how did the screenings go? And if the DMA8 has the bad hiss you described, did you get a replacement? All the DMA8's I have installed so far have been quiet.  |  IP: Logged Eric Robinson Jedi Master Film Handler Posts: 538 From: Santa Rosa, CA Registered: Jan 2005 posted 01-06-2011 02:22 PM                     I just read this White Paper on Gain Structure. While it doesn't apply directly to Cinema equipment, the concepts and methodology is explained clearly and easily so that the concepts could be applied with some studious effort. Written by: Chuck McGregor Check it out!! Advanced System Gain Structure - PDF Hopefully I'm not violating policies here by not cutting and pasting the 15 page document. It would be a great addition to the WAREHOUSE >> INSTRUCTIONAL DOCUMENTS section, if the original author permits it.  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 01-07-2011 05:35 AM                     Here is an excellent document on the subject too from RANE Note, RANE has many such good documents. They also have a pretty decent sense of humor (including in their manuals) so the read is normally not bad. -Steve  |  IP: Logged Eric Robinson Jedi Master Film Handler Posts: 538 From: Santa Rosa, CA Registered: Jan 2005 posted 01-07-2011 01:54 PM                     From Rane White Paper - Setting Sound System Level Controls URL of White Paper is above in Steve's post. quote: Music's wide crest factor of 4-10 translates into 12-20 dB. This means that musical peaks occur 12-20 dB higher than the "average" value. This is why headroom is so important. You need 12-20 dB of headroom in each unit to avoid clipping. I wonder in our environment of "LOUD trailers" if the 12-20 headroom should be increased a bit - any opinions?  |  IP: Logged

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