Film-Tech Forum ARCHIVE: SMART MOD IV Question

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Posted by Mitchell Dvoskin (Member # 751) on 09-12-2007, 09:39 AM:

A friend of mine recently hooked up a SMART MOD IV analog Dolby processor in his home screening room. It appears to be working fine, and as best as I can tell was calibrated (Dolby levels etc) correctly. It seem that Dolby A sounds much better than Dolby SR. The SR seem a little over compressed, or more specifically seems to lack high frequecies, at least as compaired to Dolby A. Yes, I realize that we are compairing different films with different mixes, but something seems not right. The unit is using the Smart Copycat 280 SR Emulation cards.

Any suggestions or advice.

Posted by Gordon McLeod (Member # 33) on 09-12-2007, 09:51 AM:

The copycat 280 like the smart a type is only a 2 band noise reduction system (dolby A is 4 band)
as such it does tend to have a more compressed sound and also the high end is rolled off moreso in the SR mode

Posted by Mitchell Dvoskin (Member # 751) on 09-12-2007, 10:30 AM:

Are the "official" Dolby 280 cards also 2 band, or do they sound better than the copycat cards?

Posted by Christos Mitsakis (Member # 143) on 09-12-2007, 11:49 AM:

Dolby 280s are the original SR cards from midle '80s. SR uses 4 (or more - don't remember without searching Dolby's papers) bands with sliding band, instead of fixed passband (A-type), filters. Yes They sound superb.
C

Posted by Steve Guttag (Member # 268) on 09-12-2007, 03:59 PM:

Dolby-A used 4-bands. SR was/is much more complicated with a combination of fixed and sliding bands (10 if memory serves)...those with fixed bands have variable gain. Those with sliding bands have fixed gain. The combination allows the SR circuit to custom tailor the NR to the actual signal it is dealing with. To that, they add what they call "spectural skewing" to deal with the extreme highs and lows (a pre-emphasis/de-emphasis system).

Posted by Louis Bornwasser (Member # 3063) on 09-12-2007, 06:12 PM:

My experience with "copycat" is they make SR sound about the same as Dolby A with Dolby A film. You fail to achieve the quality-boost we expect with real SR. Better than nothing. Louis

Posted by Mark Gulbrandsen (Member # 72) on 09-14-2007, 11:15 AM:

quote: Louis Bornwasser
Better than nothing.

I never cared at all for the CopyCat cards and this is definately a case where nothing may actually be better.

Mark