Robert Morein wrote:
"ScottW" wrote in message
oups.com...

Robert Morein wrote:
"ScottW" wrote in message
ups.com...

Powell wrote:
"ScottW" wrote

If you must compensate a limited signal
level source with more gain in your preamp
then you are obviously also amplifying the
noise of your source more than should be
necessary and diminishing overall system
signal/noise ratio.

Well, yes and no.

The volume pot is primarily used on players like
CD/DVD, phonograph head amps, tuners, etc.,
to slightly increase or reduce RMS voltage of
the player's line level outputs. For the most
part the consumer electronics industry sets
*fixed outputs/line level* at 1-2 volts.

There are plenty of alternative hybrids that
output much higher by providing preamp output
levels (5-50 Vrms). A few adequate products
were sited. Because there is so little demand
for these hybrids consumers pay a premium
price.

You would unnecessarily burden manufactures
and consumer pocketbooks with unnecessary
expenses for including additional head amp
sections in players. There is no market for this.


A better solution is a source which is capable
of rated output without distortion/clipping or
whatever problem your POS adjustable
output level CD players have.

I wasn't aware there were problems with players
not outputing at line level (1-2 Vrms). There
is no practical use for playing devices outputing
at any higher levels. When they do that's when
a pot is often included on the device.


Moron claims his Sony player doesn't even have the balls for line
level output.

reference his response to Bret's comment:

Most power amps will go full output with 1.5V rms. VTL in their book
specify they design for input sensitivity of 775 mV as I recall.

Morons response:
Yes, but from practical experience with Sony ES players, I can tell you
that
those with 5532 outputs cannot do it cleanly.

So I have a couple issues with Bob's premise.
1) His crappy CD can't even provide std line level output cleanly.
2) Attenuating said output with a pot isn't likely to do anything to
clean it up.
3) Adding extra gain later to compensate will also amplify the noise
floor of the player reducing overall system S/N.

ScottW

Scott, it sounds alot better with the preamp in. That's all I care about.

That's fine. In the future we'll ignore anything but your subjective
appraisals as that is all you care about.

Noise is not a subjective problem in either system.
Without the preamp buffers, the systems sound strained.
I use Sony ES players, known to have excellent DACs, but not the best
output
stages.

So your comments about passive attenuators really only applies to Sony
ES CD players which you find lacking in output performance.

No.

Maybe you
should have said that.

ScottW

It depends upon the player. Most Japanese players, and preamps, use
inadequate ouput circuitry. I disassembled a very fancy Pioneer Elite
preamp, and found 5532 outputs. The power supply was really tiny, using the
78XX regulators in TO-92 package. Some highly thought of Marantz players
also use them. The user has the choicee of modding, or using with a preamp
that has a good line driver output stage.

Do these Marantz players have volume control?
Most preamps have similar input impedance to an amplifier so
adding a preamp won't change anything at the output of a CD player
with fixed levels.
I think you're straining more than your CD player.

ScottW