Aligning Optical lens in a NAD C-540 CDP

[arupg]

Certainly its time to trash the NAD. DAC is a modded Audio Alchemy Dac-in-the-Box. But I have access to Accuphase products at superb prices & feel its about time to throw away all the small modded boxes and get a "real musical unit with no fuss" and enjoy the music.....

 

[PLS]

Dib ???

In past i used an Audio Alchemy DIB with Elna Audio Caps (Metalic crimson color), a Burr Brown OPA2134 mod and a DeJitter, i dont remember the name of the pack, the front is common to the two devices, but in practice is a DeJitter and a DIB without optical link. I still have it, but it sounds worse than the NAD C541! My C541 was tortured to exausthion with updates in power supply, and have 2 Burr Brown OPA2134. The DAC is a Burr Brown PCM1732, a HDCD compatible integrated filter and 24Bits Delta Sigma DAC (Bitstream), originaly NAD employ Elna Cerafine capacitors, so i kept this can, and actualy is sounding very good indeed!Its my HDCD front end!
In the past i boost the current of the laser diode and of the photodiode array, NADs circuitry limis the current of the both parts, see the datasheet of LA9240 and compare to C541 service manual, the circutry of the optical parts!
I´d love to have cash to buy an Accuphase SACD player...

Regards

 

[arupg]

In my Audio Alchemy, I have now OPA627 on brown-dog adapter working as a Dual Opamp and biased into Class-A. It sounds good. There's a lot of Nichicon Muse caps I've used along with Auricap Film also. The Original Audio Alchemy chassis was thrown away as the mods were not fitting. A much larger chassis had to be made with much superior 18V DC power supply. I worked hard to extract as much good sound as possible from this dac. Someone suggested to discard the analog output stage and use Lundahl transformers directly fom the Analog Devices DAC chips for a much improved sound.

But as I just mentioned in my earlier post, I better save some money and go for that Accuphase even if its not SACD and forget the constant headache of the NAD transport issues.

Best regards

 

[PLS]

Now i remember the Audio Alchemy model, its an Ultra DAC.

Regards

 

[PLS]

Hi again
I discover this article in the net, check it out!

http://www.geocities.com/nad_c540/

I've been running my C541 with a rectangular stone on top and an Audio Technica CD Stabilizer AT674. The feet are 4 Ixos spikes.
The AT674 is the most effective solution to cd-r, but the originals cds play fine after the LM350 mod without the CD stabilizer!

Best rgards

 

[arupg]

Hi there:

Thanks for the update on the NAD. After the diodes mod on my C-540, the transport tracks pretty fast but skips now and then.

I have a half inch thick granite tile of exact top cover size placed on top of the C-540. I have 3 Nos J.A. Michell Tenderfeet large cones (aluminum) placed under the C-540. With the cones under and the heavy granite slab on top, this has given the unit great focus.

Intend to try the Audio Technica mat sometime. But in the long run, I've lost interest in working hard towards this NAD unit. Better to save some serious money and plonk it towards another stellar unit for a hassle-free listening.

Cheers!!

 

[White Mike]

Hi guys,

Just found this thread after diggiing up my c540 (gave up on it years ago but keen to throw in these mods) and noticed the c529 cap has a burst top. It still works but my unit has the occasional random tracking issue and also the one described in the NAD service note.

I am keen to try the LM350 mod PLS suggested but without the service manual (or a little more circuit detail from PLS on the LM350 solution ) it will be tricky. Unfortunately the link at the start of the thread no longer has the files.
Anyone else know where to source the C540 manuals?

Many thanks,
Mike.

 

[mk1life]

Sorry for bumping up such an old thread, I have read through this thread and on page1 PLS refers to transistor 7808 undervolts. I have a nad c540 with the skiping issue,i notice that trans7808 heats up tremendously,and would like to know if this is the reason for skiping(fualty 7808). I have replaced the cd laser mech already.PLS,can you confirm this?thnx.