Marantz CD40 output coupling question

[colin.hepburn]

Originally Posted by bob orbell

Richard, your pictures have gone, or is it my computer. BOB

it’s not your computer Bob no pictures here ether

[Richard]

Mmm, the wonderful Virgin has gone bits up with my webspace at the mo I'm afraid. I called them and they have others logged with similar fault so let's see how long it takes...

[colin.hepburn]

Virgin again ah I think they should stick to running trains

[Richard]

Update on this output stage coupling,

All working well so I checked frequency response into the scope using HFN 015 test disc.

This disc has 10 second sine wave tracks from 2Hz to 20KHz at ref 0dB level.

Basically, connect the player to the scope and play tracks 40 - 56 whilst watching the output level and wave shape on the scope, that easy.

Result was perfect looking waves at identical amplitude to 20KHz, and exactly as the roll off calc had suggested at the bottom end;

Ref 1KHz output was 5.1V p-p = 1.8V rms.

All other f were exactly level with this except at the bottom where roll off was just perceptible at 5V p-p 4Hz and then 4.2V p-p 2Hz. That's about -2dB 2Hz and so would agree with expected -3dB 1.6Hz. Of course there's no signal and nothing audible down there anyway so the result is a good one

I then went on to swap out the smd resistors. The 2K4, 10K, and 100Rs on that circ posted were all changed for regular leaded types using metal films for the series and carbon film for the 10K shunt/load. Result isn't night and day, it does seem a little clearer, but impossible to swap back to compare again. Would I do it again? Well, easy enough to do and at least I know all the components in the analogue output signal path now so yes, and they can be swapped again for other types should the urge arise