Nos Dac worth while upgrades.....

Whilst visiting Chris123....we had a quick look in the little box. After suggestions by Isaac we did the following.

Replaced the clock resistor[not the right name ...brain has gone into blue screen mode] with 0.1% tolerance cmf from dale vishay, removed the 4.7uf blackgates on the on the output and replaced each with 5xwima 1uf 63v film caps stacked in parallel. Rewired with solid core 0.5mm 4n silver in ptfe. Cleaned the connections with deoxite and preservit from Craig Inds. Added a bypass cap another 1uf wima to the main psu cap. Though not quite a "Bloody Hell..." moment, the improvements in the bottom end and the resolution of complex musical passages was obvious. Though not the prettiest mod I've ever done, the results were far greater than the sum of the components added/changed. I expect the sound to improve as the addition beddin/burn in or what ever you want to call it.

Oh yes and thanks for the chance to listen to your system and for me to play some boring cd's !

 

A suggestion I have read elsewhere is to increase the size of the output caps. Anything upto 47uF is worth experimenting with, This will make the sound more rocking and less laidback.

 

Thats intresting ....thanks

The sound was infact far less laid back after the mods, in my opinion , the actual sound balance is now about right with the rest of the gear. A suprisingly large difference was initially made with a change of digital ic. I've no idea what the original was but, dropping one of mine in helped a lot. Though I should leave any coment about the cable changes to chris.

 

Got to say things are sounding rather good to me - admitedley not with my CDP in place at teh mo but i'm sure all will be fine on its return from Dr Zanash's!
Changes to the NOS have brought about pervceived improvement - just how much i'd be troubled to say 'hand on heart' as so many things were addded into the mix over Fri / Sat, at minimum its 'faster' for example bass has a 'THWACK' now has opposed to builing into teh note in a 'TTHHWACK' style, if that makes sense...
Digital I/C is branded 'Profilgold' - picked it up following sighting it on a long foregotten thread about VFM items - twas well regarded but the change to the silver i/c was truly a WOW! moment. Stereo I/C change was a simliar step - they replaced a Kimber PBJ.
Silver speaker cable - mind was long frazed by then but recall changes that will be investigated further in the future...

 

I also felt that the realism had increased, giving a more natural and easy or less strained presentation. Hopefully things may improve further as all the parts settle in.

 

Would be interested in hearing your NOS again Chris - any closer to psu yet?
Most of the caps on he copland were already bypassed, however the 5 that werent (power section) made a very noticable difference after adding the wimas, made me wonder why they did all the others but not those 5?

 

Cumulative effect possibly. ie, if you had done those 5 and not the others you might not have got the difference until you had done all/some of the others.

 

Hi Rob - will sort something out ref a listen to the NOS but twill be a little while off - only 2 months to the wedding and spare time is already at a premium!
As before hard to establish any true 'nos' changes as the cables have been changed as well and its not my cdp - however a quick listen to Blowers Daughter sounded really rather good.........guess we should try and ghet an unmodded NOS and a DAC64 to the next bake off and put tehm all in the pit to fight it out again.....
Not to sure it will need a dedicated PSU anymore (though again it could be brought to a bake off if available) - previous comments seem to point to more bass being the benefit, following the silver cable upgrade this last week i no longer preceive bass as a problem - (i think you had a similar moment when you changed i/c's from the Copeland) though, as before, i 'm running Petes much modded Denon CDP at the mo whilst he has hold of the 904 - i'm looking forward to seeing his list of suggested changes / getting it back and plugged in!!!

Once things are all bedded in i'll put my original cables back in to try and establish any differnces in sound - though both the NOS and CDP will have been tweaked so no way to establish whats changed where as far as the hardware goes

From there i guesss i'll consider clocking the CDP and that should do me - except for taking a green marker pen to my CD's (i gonna burn a couple of copies of a favourite cd first and get SWMBO to blind test me - just to be sure i was not kidding myself on Friday), applying damping material to equipment boxes, keeping my pins polished and making a 3 way power lead - same as Petes - using the shared wall plug thingy i bought off him this last weekend, as opposed to using a 4 way extension block.

Longer term cryo treating still gets me thinking and silver speaker cable sounded mighty fine but the spending money is currently limited to flowers and frocks - and thats just for me.....!

 

Just got sent a dead NOS III ...if I can fix it

any good mods for it ?

 

Hi,

It's a very simple thing, should be allways fixable if the PCB is physically OK.

Obvious ones:

1) Adjust Reference Resistor, I/V Resistors and Supply Voltage for best dynamic range (needs FFT).

2) Change Series regulator for DAC to CCS powered TL431 Shunt regulator.

3) Fit (switchable?) "anti-sinc(x)" filter.

4) Slow the Receiver PLL down as much as possible without taking more than 10 seconds to achieve "lock" or fit 2-Speed PLL.

Ciao T

 

The Nos III has been feed +14v through the -ve ....So what do we suspect may have died ?

I've replaced the blown BC548 ...I'm suspecting both chips will be toast but most of the rest should be ok ?