Conference cookie::notes$archive:cd_v1

dbx makes a CD player with a built-in compressor/expander, plus an
ambience control.  I can't recall offhand hearing of a separate unit
suitable for home use, but I'm sure someone else has...
				Steve

I stopped following dbx several years ago but I remember they used to include
a compander with the outboard tape and dbx LP decoder units.
  (Model 224 was one of them, I think, but as I say that was years ago.)
I'm kind of amazed that there's still a market for dbx.

Gary

re: .2

As a relative HiFi neophyte, why do you make that last comment?  I always
thought that dbx tapes/disks sounded great, certainly better than dolby B
and as good as C.

If I'm missing something, please clue me in (especially as I am in the market
for a tape deck soon!)

Thanks

andy

re: .3
Sorry, I didn't really mean to downgrade dbx.  For personal recording, I
think it's the best thing going.  It would most certainly do a wonderful
job of recording CD's.  My point is that the CD has the potential to beat
the snot out of dbx.  With portable CD players at reasonable prices and,
most likely, more car players on the way, dbx doesn't seem to be as marvelous
a technology as it did 5 or 6 years ago when I first started drooling over
it.  Few, if any, portable (personal) tape players use the dbx technique
and if you have ever heard a dbx recording played without dbx equipment,
you'll agree that you wouldn't want to use your home recordings while you're
out jogging.  (The sound is *obnoxiously* "high" heavy.)  As for using the
dbx machine for your home recordings, if you don't have a CD player, it 
is the best way to archive your LP collection.  If you *do* have a CD player,
what is the point in archiving them?

Sorry to ramble.  I just think that the market for dbx will dwindle as the
CD market builds.  Dolby seems to be the way to go, mostly for the sake of
(I choke on the word) standardization.  (And no I do *not* own an IBM PC.
:^)

With a minimum of hiss,
Gary

re .1, .2, .3, .4,

	but but but, the author of this note does not want to expand.
     	he just wants to compress! I can perfectly understand that desire.
	At times, in a car or with background music, the dynamic range
	can be too much! One might want to reduce it (slighty).
	Some cheap recorders with automatic recording level adjustment
	seem to produce this as a side effect.               
Hein.

I never actually bought a DBX - something a little canned was added to the
tapes I recorded with one I borrowed - but I seem to recall there were a
couple models that let you vary the compression ratio.  Another outfit that
made audio novelties (I use that expression because they never seemed serious
enough to make anything real well) was MXR. I know they had a compander
(variable dynamic compression/expansion) which might be worth looking for
for limited use.   If you're handy, you might want to make one yourself.
Signetics makes a chip (NE570, NE571) just for this purpose. The Signetics 
Analog Data Manual shows you how put one together, including substitution
of the marginal output opamp for better performance (of course they dont
give you any suggestions on which one to use).

Walt

Please read my response again - I said that dbx made a CD player with
a control for compressing the audio, said feature being there exactly for
the reasons requested in .0.  The fact that dbx also makes compander boxes
is irrelevant - they make speakers, too.  Another point - dbx spells their
company name in all lower case.
					Steve

Was the reply in .7 aimed at one of the replies specifically ?

Walt

Personally, after copying the 1812 TELARC disk to tape on my Nak and setting 
the cannon level to +5 dB, to intentionally round off the transients and add a 
little to the floor, I was disapointed. The majority of the music was only 
about 10 dB above the (dolby B) noise floor - hence rather hissy.

The solution (as asked by #1) was to route the CD to my VHS HIFI (in AGC mode) 
and route the output to the Nak.

I've thought that compressors were in the wings - for casette dubbing and 
background music.

					Bruce

.7 was aimed at .4 through .6, mostly - digressions about dbx compander
boxes.
				Steve

OK I think I got it.     The digression is about whether DBX (sorry dbx)
stuff sounds good or not. Right ?  Lets leave that up to the user.

Compander is nothing more than a word which describes a box who's purpose
in life is to provide compression of an analog signals dynamic range, or
expansion of an analog signals dynamic range. 

I have seen boxes marketed which have expansion only, or compression/expansion 
functions. I have not seen a consumer compression only add-on device.  I
and several others have offered a suggestion that perhaps a compander (using
the compression function here) would provide a low cost solution.  Since
I dont see where in .0 it states that the solution must be part of the
player or custom designed, it appears that a compander box is a valid
alternative.      So whats the problem Lionel ?

Walt

Re .11:
    No problem, "Clark".  It seemed to me that all these notes arguing
about whether or not dbx noise reduction boxes were worthwhile were off
the subject of "how do I compress my CD player's output".  I said
initially that the only thing I'd heard of was dbx's player with an
integrated compressor - I can find no listing of a separate box in my
magazines  (I relied on Audio's recent issue that (supposedly) listed
everything on the market.)  If there is one, of course, it would be
a better solution.
					Steve

Re .0:

	George -

	See if you can obtain a used dbx 117 or 119 compander (one of their
newer multiband models will be fine if the price is right).  Used judiciously,
these devices will do just what you want.

- Jim

re: digression argument.

Oh, for bog's sake.  What difference does it make?

re: .0
   Just for fun, I looked back at some old dbx pamphlets. (vintage 1981 or
so)  The model 128 offers a variable expansion ratio from 1.0 to 2.0.  It
offers a variable compression ratio from 1.0 to infinity.  They also threw
in the dbx LP decoder. It'd be hard to beat if you can find one.

Gary

For this it might actually be worth using metal tape.
The dynamic range is much more than other tapes.

I use them for live recording, but not much else.
CD's have enough dynamic range to need them.