Balanced vs RCA between amp/preamp

for anyone interested, HDAM module schematics are available here https://muzgdiy.files.wordpress.com/2015/05/all_versions_2.png

These HDAM's consists of discrete surface mount components with short mirror image L/R signal paths.

IMO, this is marketing malarkey. It is not possible to 'mirror image' active circuitry as devices have functions on specific pins. Marantz literature always shows a pair of identical HDAM modules and never a mirrored L/R pair which, if they existed, would be featured front and center. Additionally the Service Manual has only one HDAM-SA3 schematic for a bipolar amplifier circuit.

Discrete circuity 'suffers' from increased parasitic L & C, component tolerance and reduced supply immunity, all of which contribute to the 'sound'. Some opine that discrete circuitry takes the edge off the literally 1000's of integrated circuits through which the signal passed before the final storage medium.

Somewhat troubling is the -ve phase is derived from the post Wolfson WM8816 volume control unbalanced +ve output through an additional 2 HDAM and 2 gain stages. These then feed a pair of balanced tone control circuits. Strange.

Use caution if driving an unbalanced amplifier. Best results will probably result from using Pin 3 & Gnd ONLY.

A largely ignored electronics property is power supply linearity. The impedance and phase linearity of the ubiquitous LM3x7 / 7xM  et al. regulators vary drastically between manufacturers and implementation. Some are positively abysmal suffering 180° phase and a couple of orders of magnitude Z change in a few Hz.

Marantz makes a fair bit of 'noise' about their power supply design and examination of the schematic shows that the audio supply is discrete and well designed.

A negative in the pre-amp [and any versatile control center] is the large number of relays in the circuitry. ALL switching is audible and cumulative.

Bottom line, if you like the sound, don't worry about the innards.

PS I have a Marantz CD-6006. I like the sound & features. I don't worry about the innards.

Use caution if driving an unbalanced amplifier. Best results will probably result from using Pin 3 & Gnd ONLY.

Hi Ian,

Not sure where you are quoting this from, or if you are quoting it, but to be clear I assume this statement is intended to apply to the unusual situation in which XLR cables are used to connect the balanced outputs of a preamp to an amp which receives the signals provided to its XLR inputs in a single-ended manner, and would short one of those signals to ground if the signals on pins 2 and 3 were both routed to the amp by the cable. In most cases, of course, at least when it comes to consumer-oriented gear, unbalanced amplifier inputs would be driven by the preamp’s unbalanced outputs via RCA cables, and the statement would not apply.

And in most cases involving consumer-oriented amplifiers which provide XLR inputs but are not "fully balanced" I would nevertheless expect signals provided to their XLR inputs to be received differentially, not single-ended. As is the case with the OP’s amp.

In any event, thanks for providing the additional insight in your post.

Regards,
-- Al

I had a low level buzzing in RCA when i went to balanced it went away plus the system got quieter and more dynamic.

Hi Al,

I should have said "Use caution if driving an unbalanced amplifier from the balanced outputs."

Thanks for catching.

- Best,
    Ian

Tidbit about XLR cables and plugs.

In the late 70's I worked as a salesman at Shrader Sound in the Georgetown neighborhood in NW DC.

Bill Shrader was long out-of-the-picture, and the silent partner who kept the business afloat was Jim Canon, who developed the "Cannon connector", used at the time on lots of professional microphones.  When Jim sold out to United Technologies, they made a "Cannon connector" with a plastic insulator ("XLP") and one with a rubber insulator ("XLR").