From: michael@Canada.lsil.com (Michael Smith)
Subject: Re: Outboard Dolby Pro-Logic boxes
Reply-To: michael@Canada.lsil.com
Organization: LSI Logic Corporation of Canada, Inc.
Date: Wed, 23 Dec 1992 16:06:45 GMT

In article BKM@da_vinci.it.uswc.uswest.com, pprun@august.it.uswc.uswest.com () writes:
>
>I would like to add Dolby Pro-Logic sound to my sound system.  I realize
>that I need three more speakers (right rear, left rear, and center), and
>maybe a subwoofer eventually.  My Denon integrated amp is too nice to
>scrap for an AV amp.  So I'd like to buy an outboard Dolby box with three
>channels of amplification for my new speakers.  First off, does anyone
>have comments on current boxes (Yamaha has a fairly new one, and Audiosource
>makes a few, but I'm not impressed with Audiosource)?  Second, the manual

I have a Yamaha E-1000 unit which I'm very pleased with.  Before I purchased it,
I listened to Audiosource (the "really there" feeling wasn't there), Fosgate
(only had Surround Sound, not Pro-Logic, way too expensive, needed separate
amps), Lexicon (and I thought the Fosgate was expensive!!!), Pioneer (the
center channel crackled, arced and kinda blew-up during the demo), Denon (woulda
been my second choice) and Fisher (he he he... just for laughs of course).

The Yamaha box, even the smaller E-200 unit, does an excellent job in engulfing
the audience in sound.  The channel separation is superb (watched a Star Trek
episode yesterday and I head a voice behind me.  Surprised, I turned around...
it was the rear speakers, still gets to me at times :-) and the ambiance recovery
DSP options are also fun to play with.

The best thing to do, as everyone else here will agree with, is to go listen to
the worst Pro-Logic box you can find, then to a mid-range one, and then to
the best (THX, Lexicon, Fosgate, whatever).  Then, balance your budget with what
you like and don't like.  Don't just look at boxes in your target price range,
look at more expensive units as well.  You can probably assume that a Lexicon
CP-3 is as "good as it gets"; this will set your standards when comparing 
lower costing models that sound a little different.  

>usually states that the Dolby box is connected through the tape monitor
>circuit.  But this would tie up the tape jack.  My amp has a pre-out (output
>directly from the pre-amp).  Would this be too high a level to feed the
>Dolby box?  The Denon manual states that the pre-out rated output level is
>1.0 volt.  Any comments would be appreciated.

The "Pre-Out" is identical to your tape monitor out with a few exceptions.  These
are:

	- volume level control on your Pre-Amp
	- Bass/Treble/Bass-Boost/Loudness
	- Left/Right Balance

In terms of output level, the pre-out and the monitor-out are identical.  So yes,
you can use the pre-out to drive your DSP box (although I'm not sure if all DSP
boxes like an input signal that has been colored with bass/treble trim).

Realizing that an ideal setup for a DSP box is in a tape-loop, and that most
people only have a single tape-loop available to them, some DSP boxes have an
extra tape-out and tape-in set of RCA plugs.  So, you've just moved your tape-loop
from your integrated amp (pre-amp, whatever) to your DSP box.  The Yamaha E-1000
does have this, I'm not sure about other systems.


---
     Michael Smith - Chipset Design Engineer

Phone: (416) 620-7400         michael@canada.lsil.com
Fax:   (416) 694-5005

    _/     _/_/   _/_/_/   _/                   _/
   _/    _/        _/     _/ 
  _/      _/_/    _/     _/     _/_/_/ _/_/_/ _/ _/_/_/
 _/         _/   _/     _/     _/  _/ _/  _/ _/ _/
_/_/_/ _/_/_/ _/_/_/   _/_/_/ _/_/_/ _/_/_/ _/ _/_/_/
                                        _/   LSI Logic Corp. of Canada, Inc.
                                   _/_/_/   Suite 1110, 401 The West Mall
                                           Etobicoke, Ontario
                                          M9C 5J5