cambridge isodac s700 mods/upgrades

[JohnW]

Dan,

Glad to hear - that you also hear what I do....

John

[Shoog]

Yes it sounds thinner with coaxial. Fuller and sweeter with optical.

Shoog

[audiobomber]

Originally posted by JohnW
Dan,

Glad to hear - that you also hear what I do....

John

I'm glad you kept saying it.

I have one question I hope you'll answer for me John. When you say to upgrade the IsoMagic psu, do you mean the parts in the brick, or are there some power supply parts inside the box.?

I still don't have a schematic for the IsoMagic, so if anyone can oblige I'd greatly appreciate it. I have the DiscMagic cct if anyone needs it.

[JohnW]

Dan,

I was referring to the PSU Brick - upgrade by 2x +/-15V for the analogue section (Left & Right Channels) & +15V for the digital sections. LM7815 & LM7915 type PSU's are fine.

John

[audiobomber]

I plan to order a pair of DACT CT102 power supplies later this week. What do you think? http://www.dact.com/html/power_supplies.html

Expensive I know, but I think it will be money well spent. I've been comparing the DiscMagic/IsoMagic to a couple of more expensive players lately. I've always thought highly of the Magic pair, but now I realize it's even better than I thought. Two of these DACT units won't come close to the price I would have sunk into another player.

[JohnW]

Hi Dan,

The Isomagic (and CD4SE) are the best designs I did for Cambridge Audio, so I'm glad you are also discovering there Magic!!!

Forget ordering the PSU you Linked too, these are switching units, and as there Switching Frequency is not Sync. to the DAC operating Frequency you will get Spurie due to "beating" between Clocks - go for a simple LM7815 / LM7915 type PSU.

John

[Kram]

I have just put together two P05 power supplies from Rod Elliot, I am sure that most of you know that they use LM7815/LM7819 regs.

I think they sound just fine, although I have never heard the DAC with the original PSU as I bought the DAC without one.

I am going to rig up another +15v supply in a few days for the digital supply, this time using a LM317.

Dose any one have any preferences for LM317 over LM7815 or vice versa? Any particular reasons?

Thanks
Mark

[GrayZee]

Hello John,

I've upgraded the IsoMagic with a nice LM7815 & LM7915 type PSU and am really pleased with the results. Trouble is I think I heard you say the next big upgrade was a discrete output circuit? Any clues as to the circuit you used?

I have the IsoMagic running on the end of a M-Audio Transit at the moment and I keep coming across the term 'galvanic isolation' to isolate it from the PC. I'd love to know how to acheive this as the PC ground must be connected for the transit to work.

You've probably heard this a million times John but I think the IsoMagic is an amazing design for the money and it's given me many hours of beautiful music and lots of fun trying to tweak it. You must get quite a buzz from your acheivements!

One last plead: has anyone got a circuit diagram for a IsoMagic?

Thanks,

Gray.

[audiobomber]

Originally posted by JohnW
Forget ordering the PSU you Linked too, these are switching unitsPSU

Thanks again John. It must be tedious for you talking with a mechanical guy.

I thought the DACT unit might work if I used the existing IsoMagic PSU to feed it instead of the switching supply. There was a link on the DACT site showing a DIY DAC where he's fed the PSU with a 12V wall wart. I'm not sure where the third +15V supply would come from though. Split it off from the analog +15?

What about this Welborne Labs unit? http://www.welbornelabs.com/ps1.htm

I know you're saying a basic LM7815/LM7819. I'm not trying to be thick, but I'm looking for maximum impact, without worrying too much about price. Regardless of the regulators used, would two power supplies be likely to improve the sound at all?

[JohnW]

Dan,

Expensive but OK, you would need 2 of these units one for each channel, and one POSREG version for the Digital section,

John