"Arny Krueger" wrote in message
...
"Trevor Wilson" wrote in message

"andy" wrote in message
oups.com...
As yet another owner of a Pioneer DV-575A I am curious about what
the
above modifications will achieve and why?

**Output muting, via the use of BJTs has always been a sonic
disaster, IME.

Musta never seen it done right.

**Perhaps.


A relay contributes no distortion,

As long as the contacts are good.

**Relays (and BJTs) when used in muting circuits, are usually shunt devices.


whilst in the O/C mode.

In which case there is no signal at all.

**See above. O/C, means the signals is not shunted to ground.


The output IC used, whilst adequate, is hardly state of the
art. Output ICs in 1983 (ie: First generation) CD players were
superior. In Philips derived machines, that usually meant an
NE5532/5534 chip. A fine chip, back then and still a fine chip
today.

Right, but just because it aint' a 5532 doesn't mean it sounds bad or
contributes any audible flaws at all.

**I never said otherwise. The 5534/5532 has other benefits. As do other,
more contemporary devices.


There are two, 220 Ohm resistors in series with each O/P IC. These
should be shorted (after replacing the ICs with a more suitable
device, of course).

Why? Aren't building-out resistors good practice?

**Artificialy raising output impedances simply makes no sense at all.


A 440 Ohm output impedance is pitifully high.

Isn't 600 ohms the standard source impedance for audio production?


**Nope. 10 Ohms would be closer to reality.


Additionally, it would be nice to organise a spilt rail power
supply,
for the output IC. At present, it is powered by a single rail
supply,
thus a large electrolytic coupling cap is required.

What's wrong with a well-biased electrolytic?

**In a properly engineered circuit, it is not necessary. No capacitor is
ALWAYS better than ANY capacitor. Ever wondered why amplifier manufacturers
began elminating them from their products back in the mid 1960s? Hint: It
was not a cost cutting exercise.


I suggest anyone who is interested, to compare the 575A to a decent,
contemporary CD (only) player, such as a Rotel RCD951 and report on
any differences.

I suggest that Trevor quit pontificating and do some bias-controlled
listening tests of his own.

**Done. In fact, I did so, earlier this week.


--
Trevor Wilson
www.rageaudio.com.au