LME49860

[buelligan]

Has anyone tried the National LME49860 in the X-DAC v3?javascript:add("%20:'(")

I read about it in a Stereophile bit and it looked like a good candidate.

I was thinking it would do a great job in the I/V stage because it is so fast (GBW product = 55MHz).

I've been reluctant to mod my DAC because of the warnings about PCB trace damage, but I'd really like to see what some modding can do.

Any direct experience or even just opinions would be appreciated.

Thanks,
buelligan

[Deleted]

buelligan

If you want some modification ideas for the X-DAC V3, go back to March 2007.
rockgrotto.proboards39.com/index.cgi?board=q&action=display&thread=2068

As well as using a dual regulated +-15VDC supply to feed the X-DAC V3 instead of the supplied wallwart, you can also add a JLH between the regulated supply and it's output, in the same box. This supply can also be used without any internal modifications to the X-DAC V3 if required. The analogue stages in the X-DAC V3 do not have any voltage regulation, so this alone will improve performance.
SandyK

[dejanm]

In addition what SandyK said, you may take a look here:

modhifi.blogspot.com/

there are a couple of interesting ideas as well ... You have to scroll a bit to reach DAC V3 modification description.

Concerning OP Amps ... If Burson Audio is a bit too much for you (they are a bit pricey) then I would suggest you to try OPA2111. I replaced first NE5532 with 2604 in my tuner and in my V2 X-DAC and that was an improvement. But when I replaced 2604 with 2111 that was a real improvement. 2604 produce somehow a rather laid-back sound. 2111 are more open, with much better dynamics. You may find 2111 on eBay much cheaper than on RS Components or other official internet sellers.

[Deleted]

dejanm
IMHO, most of that is typical expensive "fiddling around the edges" It does not address the real problem, which is a lack of voltage regulation for the analogue stages, and does not result in a neutral sound stage.Without regulation , the voltage supply to the analogue stages is a not very well filtered typical 17.5V. As well, there is still some interaction between stages.
SandyK

[dejanm]

Sept 10, 2008 6:29:00 GMT @sandyk said:

dejanm
IMHO, most of that is typical expensive "fiddling around the edges" It does not address the real problem, which is a lack of voltage regulation for the analogue stages, and does not result in a neutral sound stage.Without regulation , the voltage supply to the analogue stages is a not very well filtered typical 17.5V. As well, there is still some interaction between stages.
SandyK

SandyK,

I agree. That is why I said "in addition to ... ".

[traf]

I have installed 8 pin sockets in X-24k, X-DACv3, A5 DAB(modified to act as a DAC) and (most nerve wrackingly) in my KW250S.

I have tried LM4562, LME49720 and LME49860 in the DAC stage in conjuction with other mods (Schottky diode rectifiers and various capacitor upgrades). Sonically I have not noticed any difference between the 3 opamps - the only spec difference is that the 49860 can tolerate a higher voltage supply.

I would always advocate upgrading the rectifier diodes (MBR1100 or 11DQ10 Schottky) as its easy and cheap.

In all cases the change resulted in increased detail and transparency which upon first listen can be a little overpowering (especially compared to the stock 5532). Bass extension was also improved, but with an initial lack of 'weight' which disappears over time. They do settle (or more to the point the other mods settled) in to provide an improvement which I was more than happy with. Part of the reason they are (IMHO) good is the high PSRR which makes them 'less intolerant' of the power supply quality (not to say that further improvements are not possible).

I always find that there is a knack to removing opamps and inserting sockets without lifting fragile pcb tracks. If it helps this is how I do it:

- Remove the existing opamp by snipping all the legs off to remove the 'body', leaving just single legs soldered in.
- While heating the solder blob using a lower power iron, push a leg out using a 0.5mm drill and remove the heat, but leave the drill in place pocking through the pcb.
- As the solder and drill shrink differently as they cool, you can then easily remove the drill leaving a nice clear hole into which a socket leg will fit. You might have to give the drill a bit of a wiggle!

hth

simon

[Deleted]

SandyK

Have you any idea how the X-Dac v3 standalone PSU compares to a JLH/wallwart setup? I have the PSU but if anything else was thought to be better, I'd give it a try.
Syd

[Deleted]

juke
You can't use a JLH with the wallwart. The output from the wallwart is AC. You need a dual regulated PSU such as used with the SC HA project, which provides + and - 15VDC. The internal diodes in the X-DAC V3 will then "steer" the incoming DC correctly. However, if the DC from the dual regulated supply is connected correctly, the main bridge rectifier in the X-DAC V3 ,which supplies the analogue section may be bridged out .(removed) for improved results.

SandyK

[Deleted]

Thanks sandyk, shows I'm a novice! I always assumed wallwarts and their like output DC only. Still interested if you think the JLH/modified V3 setup would be any better than the X-PSU, probably not?
Syd

[Deleted]

Syd
Definitely better. X-PSU is still A.C. The use of the dual regulated PSU also provides voltage regulation to the analogue section which the X-DAC V3 lacks, as well as a cleaner supply to all other sections.
SandyK

[Deleted]

Syd
Definitely better. X-PSU is still A.C., but higher current capability. The use of the dual regulated PSU also provides voltage regulation to the analogue section which the X-DAC V3 lacks, as well as a cleaner supply to all other sections.
SandyK

[Deleted]

Sandyk
Getting the hang of this now. I was meaning the X-PSU used with the V3 X-Cans but I have the V3 X-Dac as well so more studying needed! I suspect I'll be back with a question or two.
Syd