Isomagic schematics and mod hints

[TomasF]

Hi!
Last week I got hands on a Cambridge Audio Isomagic S700. Paired with my old Discmagic it sounds really nice! Of course the unit will be upgraded! Help would be most appreciated:

1. Does anyone have schematics?

2. I'm planning to upgrade opamps, currently AD711 + AD712, maybe for LT1468/LT1469 that I have used previously. Anyone who knows if BOTH opamps are worth replacing? Or just the 711 that is closest to the output?

3. Have you done a successful upgrade of Isomagic? Please describe!

BR /Tomas F, Sweden.
(Yes I DID use the search function)

[TimA]

Thomas,

I am about to modify mine too. I don't have any diagrams either but I believe the two AD712s perform I/V conversion for the DAC's differential outputs and the AD711 is an balanced to unbalanced convertor. I plan to replace them all. It is my understanding that there are no official schematics for this design.

Do you like the LT1469, I am hoping to try it myself soon?

Tim.

[JohnW]

Hi Thomas,

I'm the designer of the IsoMagic, however I did not keep the Circuit of the Isomagic once I stop working with Cambridge Audio.

However, I should be able to help you with any questions.

I would change the AD711 first - really a discrete Opamp would work best here.

You should also improve the PSU,

John

[TomasF]

Hi
thanks for the replies. Status update on my isomagic modifications:
* last spring I updated AD711 + AD712 for LT1468/LT1469. I have auditioned LT1469 very carefully in another design, I like it a lot. One of the best.
* I also started running the digital parts (5V) of a battery, a cap and then into the existing 5 V regulators. The 12 V voltage of the original PSU bulb raised some V when freed from the 5V job, so I continued to use it however with an extra "layer" of regulators.
* recently I biased the LT1468 towards class A using a constant current diode.
Added together those three small steps resulted in quite a sound when Isomagic is used with ClockLock with Diskmagic.
/ BR Tomas F.

[elecon]

Originally posted by TomasF
Status update on my isomagic modifications:
* last spring I updated AD711 + AD712 for LT1468/LT1469. I have auditioned LT1469 very carefully in another design, I like it a lot. One of the best.
* I also started running the digital parts (5V) of a battery, a cap and then into the existing 5 V regulators. The 12 V voltage of the original PSU bulb raised some V when freed from the 5V job, so I continued to use it however with an extra "layer" of regulators.
* recently I biased the LT1468 towards class A using a constant current diode.
Added together those three small steps resulted in quite a sound when Isomagic is used with ClockLock with Diskmagic. [/B]

Thanks TomasF for sharing your experience. I am just in the process of buying a DiscMagic and IsoMagic set from a Canadian (first) owner, and the equipment is supposed to be in original first rate condition. I would like to try a similar route for modifications as you have done.

Cheers!