In article , Trevor Wilson
wrote:

"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.

FWIW The Quad 34 uses BJTs for output muting, but sounds fine to me.
Certainly doesn't sound like a 'disaster' to my ears. :-)


A relay contributes no distortion, whilst in the O/C mode. 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. 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).

Personally, I would always use series resistors at the output of a source
device or preamp. It allows you to define/limit the range of load
conditions the source output stage/IC will experience. Without this you may
produce problems in some cases.

A 440 Ohm output impedance is pitifully high.

Personally, for domestic sources I regard the order of 600 Ohms or less as
being fine unless there are special circumstances.

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.

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.

Well I do use a Philips DVDR70 (DVD video recorder/player) as well as a
Meridian 200. However in both cases I send their digital output to a
Meridian 263 to obtain the sound. :-)

Slainte,

Jim

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