cambridge isodac s700 mods/upgrades

[JohnW]

Smithie,

The HDCD decoding problem would suggest the Data from the CDR is no longer 'Bit Accurate" most likely your CD player is having trouble reading your CDR - corrupting the Data Stream.

Clock Lock issue is very strange - are your sure it’s not the input Lock Light? I cannot understand how the Light can flicker when the Switch is "Off" as there’s logic that disables the Clock Lock Circuit - suggests a Dry Joint on the PCB.....

John

[smithie]

hi john
thanks for getting back to me,you might be right concerning signal lock light.
when i got it that light never came on(second one in from the left marked locked) so i asumed it ment locked when using the clock lock switch on the back,but if im reading your post right then the locked light is just stating that its locked to the output of the transport,if thats the case then me popping the lid means ive cured a fault that i never knew was there...cool!
is there no indicator light for the sync switch on the back when in use?
thanks for your thoughts regarding the hdcd problem,does that mean the cdr is deteriating and losing the bits or the marantz dr6000 recorder cant read its own recordings properly??? in which case that sucks!
anyway hope your well and have settled in over there ok.
all the best
smithie
(ps ive resisted the urge to ask how your new gear is doing...but its been hard)

[JohnW]

Hi Smithie,

Guess it was a loose connection on the 'Lock" LED.

“Clock Lock” is only indicated on the Transport - and not the DAC.

Yes, sounds like your CDR recorder is fading - try different Media (Discs). If the Bit Error is so large that HDCD does not decode correctly, then this will also have a large impact on Audio quality. CD Error correction can hide a multitude of sins you did not know existed – but the Data will no longer be "Bit Accurate" if the error rate becomes too large.

John

[smithie]

thanks john
i shall try some different media although it was a sony audio disc so should of been ok...or maybe not,ill have a play and see where the fault lies...all these hidden sins....should be banned!
smithie

[GrayZee]

Hi All,

Just been reading about your problems Smithie with your HDCD recordings. Have you managed to sort it? Well at least you had an excuse to open her up at last!

I've finished building my PSU and it has improved the sound immensely. Still haven't put it in a nice case yet as I've been too busy enjoying the music. Well until today that is.

I tried my first HDCD disc this morning and the HDCD indicator didn't light until it got to a very quiet passage at the very end of the third track! It doesn't light anywhere else!

Could it be down to my Rotel RCD965BX I'm using as the transport? Anyone got any ideas as to why this is happening?

Oh and did anyone see that Isomagic on ebay recently - went for £132. Much more than the usual Dacmagic's.

One last thing - I'm determined to use the Isomagic with my computer and have bought a PCI sound card with optical and co-ax outputs. Can't say I can hear a difference between them but I'd really like to try a USB connection incorporating the 'clock lock' feature from the Isomagic. If anyone has some idea how to do this please let me know.

Thanks,

Gray.

[GrayZee]

Quick update - exactly the same problem using my DVD player as transport! Dodgy disc? Did EAC rip and same problem .

[JohnW]

Gary,

I've been working with DVD player recently and have yet to find one that gives a "Bit Accurate" Digital output.

Some players seem to attenuate the output by a fraction of a dB, and / or have "Dynamic Range compression", lower level signals are “Bit Accurate”, but higher levels become compressed.

Try to use a CD player as the transport - also the Jitter from the DVD player is also much higher.

Sound like a problem with your Disc copy - try using the original...

John

[Kram]

Hi GrayZee,

Any details on the PSU that you made?

Mark

[Shoog]

I have been using a toslink to hook the signal out of my Diskmagic to my Dacmagic, and having read this thread I though i would try using a coaxial connection to see if it would change things. Indeed the sound seems different.
However the manual seems to suggest that clock locking only works with optical signal out. Indeed on startup the dacmagic now no longer does that buzzing thing which I take to be the two machines establishing the clock lock (a muting relay probably). This suggests that there is now no longer clock lock.
Anyone care to express an opinion on this ?

Shoog

[GrayZee]

John,

I've tried two CD transports and the optical output from my PC (running foobar 2000, ASIO and Kernal Streaming) and even a PS2 and they all give identical results. It's a new original CD I've tried and also a ripped copy of it using EAC which also behaves the same. It lights up the HDCD LED towards the end of a few of the tracks. I'll try and find some more HDCD encoded CD's in case I have a duff disc. I just hope it's not a problem with my Isomagic .

Hi Kram,

Well basically it's a fairly standard regulated PSU. I found a decent sized toroid from a Home Theater System which had 2x13.5v and 2x15v output voltages. I used the lower voltage to power a standard 1A 15v regulator for the Digital stuff. The higher voltage runs through two bridge rectifiers which in turn powers 4 1A regulators keeping the negative and positive rails independant. It's based loosely on the circuit at http://www.zero-distortion.com/techn...powersi_05.htm with regulators stuck on the end. The biggest improvement in sound quality has been extra clarity with more air and space on appropriate recordings. Mind you I was using a very 'quick and dirty' circuit before so I don't know how it compares to a standard PSU. It was well worth the effort though.

Gray.