So I was bored...

...so I decided to take the lid off my cd transport and have a look inside, with a view to some modifications.

The equipment in question is a Cambridge Audio discmagic 1, very much a budget component in that I bought it second hand for less than £90, but it is the cheapest way I've seen yet to get a transport with an AES/EBU digital output which is apparently the best digital interface for use with a DAC.



There are some other things which to my relatively untrained eyes seem reasonable design features, namely separate 'custom power' supplies (albeit non-toroidal) for the digital output section and the servo & control board, the copper shielding around the output board. I think the cd mechanism itself is a Sony.

Theres an optical clock input, and a DDD interface input, I have no idea what the latter is for and since my DAC (modded M-Audio superdac) doesn't have its own clock or clock output, then I'm presuming the former is of no practical use to me?

I had considered getting a Pioneer DVD-575 as a transport as come September I'll probably want to play DVDs as well, but I reckon the Cambridge I have already has some potential anyway, and with AES/EBU output would be a better transport than the Pioneer which only has co-axial.

The mods I had planned to do myself:

- Damp the players casework with Dynamat
- Add additional copper shielding, between the two power supplies and in the bottom of the player.
- Damp the clock and surrounding areas of PCB with blue-tak (I have a problem here though in that I don't recognise any component as being the clock, I am looking for a small silver 'can', but theres nothing like that on the PCB, what else could it look like? I presume its likely to be on the digital output board rather than the other PCBs)

Then I had hoped to get a Trichord clock and clock PSU fitted. However I was wondering given the DIY expertise present here what else would be worthwhile? Replacing the large capacitors on the servo board? Better internal wiring?

I have little to no skills with a soldering iron but I do want to learn since DIY seems to offer great sound per pound, and I feel this could present an interesting budget project which could yield some fairly good results - I have 4 months off from uni this summer so time is not an issue, only the skills which I figure I'll have plenty of time to learn.

 

What are the part numbers on the chips next to the AES/EBU output? I assume that they're logic buffers, which are reclocking the output back to the master clock which may well be located on the servo board or even within the transport unit itself. The logic would be a similar setup to the trichord DOB in how it reclocks the data, so improving the accuracy of the master clock should reap good rewards. If the clock is located on the servo board or in the drive there may well be some significant improvements to be made to the clock that reaches these output buffers.

 

Yes, clock first, then look at caps and stuff later.

 

wrap the wires in silver foil and attatch to ground? there used to be a thread in the diy section started by zanash which had loads of ideas for modding your cd player from replacement clocks to painting the inside of the cd compartment green.
cheers


julian

 

I can let you have a rom with all the info on if you pm [small cost to cover materials/effort and postage]. Alternatively do a search in the DIY section.

 

that's odd it's not there any more ?

So I still have a copy ! The disc has about130meg of hifi bits and peices articles and modes for any numbers of players. I'm still working on the lay out...but getting there.
I had thoughts of sell it on ebay ! They get away with all those crap self hellp book things so why not one on hifi?

 

Is the thread missing?... it shouldn't be!

 

I searched under : zanash to get all my posts so could have missed it ?

 

Naw its me, just found it.....

https://www.audio-forums.com/as-rediect/showthread.php?t=7287&highlight=generic+mods

So look here for ideas !

 

So I can call back the search party?

 

Yes Yes send em over when they get back.....Hot chocolate all round.

 

isn't this the clock?

 

Its certainly the crystal ......and is likely to have the clock arround it.

 

Could that be for the DOB though?

 

Hum.... I had a dac magic three with a similar topology but ....without the thing in front of me [or a better photo] you could well be right.

 

Had the thing opened up again today to dynamat the innards thank you for the information posted in that thread Zanash, I shall be pursuing them further where its within my capabilities!

The component pointed out by Warren M does appear to be the clock crystal, indeed it says 16.3944 on it which I am led to believe is the correct frequency for clock replacement modules from trichord for this particular player.

Isaac, the ICs nearest the AES/EBU output are as follows.

2 marked:

74HC74N
VSLO9HPS
Cnn9531E

2 marked:

SBACHO
SN74HC04N

And the large yellow block component is marked:

NAiS
DS2Y-S-DC5V
AGY2329

Any ideas?

 

Bump....just interested in what you make of the chips by the AES/EBU output, to see if it does function in a very similar fashion to the trichord DOB. The clock seems to be on the digital output board too

 

74hc74 is a dual D-type flip-flop, so this is almost certainly buffering the two output pins on the AES/EBU.

The clock being on the output board is unsurprising, and is a sensible bit of design. Any jitter arising through the rest of the transport is eliminated at the d-types as they reclock back to the master clock, which is local to them. Then it's just the inherent jitter of the clock, and the jitter arising through the transmission and receive chain.

The best way to boost the performance of the discmagic will be to put in a better master clock. It's probably not worth spending on the clock 4 though, given what the discmagic cost to start with, so I'd think that the clock 2 or similar (around £50) would be a good choice.