From: daver!cypress.com!cadntl.com!szh@decwrl.dec.com (Syed Zaeem Hosain)
Subject: Re: Connecting NAD 5000 to Aragon 4004 directly
Originator: tjk@csd4.csd.uwm.edu
Reply-To: cadntl.com!szh@cypress.com
Organization: CAD National/San Jose, CA
Date: Thu, 30 Jul 1992 13:05:13 GMT

In article 14785@galileo.cc.rochester.edu, eric@prodigal.psych.rochester.edu (Eric Hansen) writes:
>Esteemed Audiophiles:
>
>I'd like to connect a CD player directly to an amp, thereby eliminating (or 
>rather, postponing until funds permit) the need for a preamplifier.  The
>CD player is a NAD 5000, which has variable output, and the amp is
>an Aragon 4004.  So, I have several specific questions -- any help from
>people who use/have heard this type of (or similar) arrangment would be much
>appreciated!
>
>1)  I've been told that connecting a CD player directly to the amp will
>  theoretically provide the 'purest' sound possible since there's
>  basically nothing in the signal path.  I've also heard that while this
>  is true (and only possible with a variable output unless you like your
>  music very loud), the op-amps inside the CD player which make this possible
>  are usually not so great -- suitable for headphones, but not great as
>  compared to the gain stages which are built into legitimate preamplifiers.
>  Anyone know about the volume/op-amp stage of the NAD 5000?
>
>2)  There has also been question as to the dynamic response which is
>  heard without a preamp - namely, if there is a lack of it.  Since I've never
>  used this arrangement, I don't know.  Most salesman have told me that
>  to get the best dynamics, you *need* a preamp - of course, to make the
>  most profit, you *need* to sell the preamp, so I don't know how
>  accurate this claim is...  It certainly seems reasonable to invest in
>  the preamp if your dynamics will otherwise be lacking, but is this
>  the case?

If you were to use the *same* output jack to feed into the preamp, then the point is
somewhat moot, isn't it? for both these issues? You would have the CD player electronics in the signal path, no matter what.

The combination you are thinking of *should* work. The key is to look at the
input sensitivity of the amplifier. If the max outout of the CD player (should
be 2.0 Volts - based on some standard which I forget) can drive the amplifier
to its full rated power, then the extra gain of a preamp is *not* essential.

Be warned - a variable output is *ESSENTIAL*. If you connect a non-variable
output of a CD player to the amp, you will be looking at expensive speaker
and/or amplifier repair costs if the protection circuitry anywhere fails to
work correctly! "unless you like your music very loud" is a tremendous
understatement in this regard <grin>!

BTW, my reason for having a preamp is the extra control. I have multiple sources.
I do not want to play with patch cords every time I change the music source.
While I do consider myself an audiophile with reasonably decent listening "ears"
(maybe not golden <grin>), I think that the benefits of direct connection are
*minor* compared to other things - like tuning your room, getting good electronics
and decent cables, etc. My advice (FWIW): get a good preamp that compares in
quality to the amplifier and CD player.

>
>3)  Last but not least, there's the impedance matching issue.  The
>  Aragon has in input impedance of 22 kilohms.  The NAD has output of 120
>  ohms.  Assuming that one of the principal jobs for the preamp is to match
>  impedances between sources and the amp, is this difference of impedance
>  a big problem?  Will it cause things like hum and/or low volume ceilings?

This is an easy one to answer. Generally speaking, if you connect two
things like this, the *lower* the *output* impedance of the *source* (CD player or
preamp) and the *higher* the *input* impedance of the *destination* (AMP), the
better off you are. You do not need to think in terms of impedance matching
since you are interested in sending voltages (the signal), not power transfer.
The values for the two items you are looking at will work fine and minimize
cable capacitance effects.

>
>Since I'm no salesman or electrical engineer, I don't know if (and to what
>extent) I am misinformed, but that's why I'm trying to learn from this
>group.  Thanks in advance for everyone's help!

You are welcome.

>
>Thanks,
>
>Eric Hansen
>

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