Jamesy

Yes that transmitter looks fine - it is a 5V part which is correct. You may find that it'll work fine without the cap but it would be much better practice to put one in. Digital parts like these switch very quickly so need (relatively) large transient currents. If you don't put a cap there you'll probably introduce more digital noise into the power supplies than if you do put one there, and that's never a good thing. It doesn't need to be 0.1uF though, if that's what you're asking. Datasheets usually list the smallest possible capacitor that you should use, *generally* speaking a bigger one is never a bad thing, but they cost more and manufacturers don't like to make their parts look like they need expensive parts to work properly.

Sorry to drag up an old thread... But I'm happy to modify MD decks for optical output, I'd rather not bother with portables though - that's a clever mod the guy did but he can't put it back together! Based in Edinburgh, UK - give me an email or PM if interested.

Some good CD players have optical/coaxial inputs so you can use their DAC, does your Marantz have this capability? There's a Cambridge Audio CD player which does this, I *think* it's the 740C (and possibly other models). It has at least one nice Wolfson DAC in its output. It may also be possible to change the DAC inside your MD, you'd be surprised how many parts like this are pin compatible. I think though, as others have said, what you're probably hearing is the fundamental limitation of the MD format - it is compressed. And while replacing a cheap DAC with a better one will make the situation better, it won't get you past this limitation.

Sorry to drag up an oldish topic but just for reference of anyone who fancies doing this, there is not a chance in hell that this will work. The optical splitter you have will be for splitting an source to two different destinations, using it effectively in reverse won't work.

Also, those caps are polarised, have you definitely got them the right way around? I must admit I haven't read everything thoroughly so you may already have checked this, but try swapping the mics over - I find these mic capsules very easy to damage by overheating when soldering.

lol, valid point. I don't put them in my ears, I just let them hang round my neck and point them outwards a bit, sounds fantastic.

Nice thread this! I made up some mics recently and they perform well. They're hidden inside some headphones to be descreet. I actually us foam on them too, not pictured, but you get the idea.