[Xander]

I don't do too many interesting projects that often anymore, but I figured this one was unique enough to add. Not sure if it's been done before, though I'd bet it has.

Not really DIY.. Sortof a mutilation project. Whats inside that you can see, is a OpAmp based amplifier, sortof like the cmoy but with a lot more balls. Changed the economy DAC to something much better, and fiddled with opamps in output stage too, as usual. Sounds a bit better than you're average stock CD player for about 130 dollars, but for $8 at a thrift shop + parts, not at all bad sounding! And a built in headphone amp, who can go wrong! I also mounted my own pot, as apposed to utilizing theirs (cheap) and used the existing headphone jack, though removed the pop-click filter they had on it, which sucked the life out of any signal passing through it.

I appologize for the horrid pictures, I have to post them locally on the server since I have no web space to put them, so the size and quality is limited, but it'll give you an idea of the horrific things done to this poor little player....

 

[Xander]

Perspective shot.. Btw, this CD player was REALLY empty.

 

[grahamndodder]

Did you test it as you went? Where did you get the best "bang-for-buck"? Was it the new opamps or the new DAC? Was the opamp easy to sub, ie.e are the pinouts pretty standard?

Also, I would consider using the former RCA outs, which I am assuming you just disabled with a little "vasectomy clip," for a second-source input.

Have your new volume pot on the front, plus a switch to choose CD (internally wired path) or aux (XM, Ipod, etc) which would now come in thru the old output RCA's. I'd prolly swap 'em for golds tho. $3.99 at ratshak would be all the money (plus the switch) to turn this into a very neat multi-source unit.

GnD

 

[Xander]

The OpAmps are just OPA2134's. It's what I had on hand. I did mount the volume pot on the front. Looks like it belongs there, too. I thought about multi source, but I dont really need it. As far as the RCAs, I removed them completely for extra room. Theres just two holes there now. I did test it as I went. The DAC was the last thing to modify. It came with a pretty cheap "economy" dac (not sure if you know, but in short, this is a really stripped down dac that has a slightly different input format then the norm.) Replacing this stuff was NOT easy. Even the clock frequency had to be changed via new crystals, and some of the circuitry did not like that. It is working nicely now, however. The DAC that I used was a pretty cheap analog devices chip, not sure what one exactly, as I had pulled it from another, older, unit. I'll have to get back to you on that, which envolves taking circuitry out of the CD player, which is kindof annoying.

 

[Xander]

Oh, and to answer your question, the DAC made the hugest difference in sound. The OpAmps nearly didnt change the sound at all, and this would have been the same with even higher "reguarded" ICs as well, since I've done quite a few mods on other players. So those people out there who despise the OPA134 because they tried to make it drive 300ohm headphones with not-so-spectacular results need to sit back down. I've never seen a CD unit, even very cheap (sub-100 dollars) that had a disgusting OpAmp in it, like the TL072, for example, which should NEVER be used for audio purposes.

 

[eric343]

Hey! My Arcam came stock with a TL072, and it sounded pretty darn good. (sure, I rolled the opamps, but that's beside the point

)

 

[Xander]

Quote:

Originally posted by eric343 Hey! My Arcam came stock with a TL072, and it sounded pretty darn good. (sure, I rolled the opamps, but that's beside the point )