[ianh-head]

A ways back (on page 58) in this blog there's some discussion about modifications to a component - transistor Q3. Some models of the D18 have a heatsink attached, whereas some didn't. Mine has no heatsink. After 3 years of reliable use and good performance component Q3 smoked itself. After a brief smell of baking bakerlite and a whiff of smoke from the ventilation slots the sound became quieter, so I turned it off. After inspecting the PCB I noticed Q3 was cooked to the point it had turned to white, friable ash - to the extent I'm unable to read the part number. I'd guess its been on the way out for a while. Further, I think Yulong probably realised it was prone to overheating since they put a heatsink on (maybe) later models.
 
I contacted Yulong who haven't been particularly helpful, requesting the entire unit be sent back to them. Me, I'd rather take a punt and just change the component, but Yulong appear exceptionally reluctant to divulge what type of transistor it is.
 
I'm humbly requesting that any Head Hi-Fier who's got their D18 open and can see what breed the transistor is could tell me ? Thanking that kind person in advance.
 
(image missing)
 
 

 

[sandab]

I just checked mine and it has Q3 heatsinked.  This looks like a factory patch since the lead of R53 has been soldered directly to Q3's emitter, replacing the board trace.  The heatsink and glue though prevents telling what Q3 is, but it looks like some jellybean NPN BJT (2N3904 or BC5xx, BC377, or whatever) used as an emitter follower with R53.  I suspect you can use pretty much anything in its place.  I'd try a 2N3904; they're pretty low noise.  I don't see a base resistor off hand near its base, so it's probably not a low Vce(sat) device.  Since there's only one Q3 my guess is it's used as an EF to power something.
 
BTW, mine also has a big patch of flux around U11... looks like it was reflowed and not fully cleaned up afterwards.  Ewww.
 
Edit: it could also be a low-power regulator (akin to a 78L05)... but the board silkscreen has BCE for the pins, and I doubt any of them are grounded (didn't run a continuity check).

 

[sandab]

BTW, wear a wrist strap when poking around; the OPA604 op-amp next to Q3 is a FET device so is very ESD sensitive.  A wild guess would be the follower powers the OPA604 which amplifies or buffers the IIS input bitstream and the use of a FET op-amp powered by a follower is for noise isolation purposes.  They haven't connected the trim pins of the op-amp, but I guess for this purpose a bit of input offset doesn't matter.

 

[ianh-head]

Thanks for your prompt response, its greatly appreciated. I'll have a crack with a 2N3904.
 
Cheers - Ian.

 

[quanghuy147]

I have just bought XLR-to-RCA adapters at the price of $16 in a local store, I have tried the XLR output after using RCA output for 2 years, a feeling that XLR output does have a different tone that worth trying.

 

[hakushondaimao]

Just an FYI, but Grant Fidelity (North American distributor) is running a Digital Demo Unit and Open Box sale from Oct. 12-21, and there are some D18 units available (while supplies last). I'm not affiliated with them, but do know the owner. Some good deals to be had.

 

[quanghuy147]

Hello,
Could you kindly suggest a USB to optical or coaxial converter that can use with this D18 DAC, as it has no USB input. I searched on Internet , there is Yulong U18, but this is very difficult to find on 2nd hand market.
Thanks!

 

[Chodi]

  Hello,
Could you kindly suggest a USB to optical or coaxial converter that can use with this D18 DAC, as it has no USB input. I searched on Internet , there is Yulong U18, but this is very difficult to find on 2nd hand market.
Thanks!

The Gustard U18 is inexpensive and does a fine job. I owned the D18 for some time and it is a very fine dac but it does require a good usb adapter to get the best out of it.

 

[quanghuy147]

The Gustard U18 is inexpensive and does a fine job. I owned the D18 for some time and it is a very fine dac but it does require a good usb adapter to get the best out of it.

thank you for your suggestion, but you mean yulong U18 or Gustard U12? I cannot find Gustard U18 .

 

[Chodi]

thank you for your suggestion, but you mean yulong U18 or Gustard U12? I cannot find Gustard U18 .

Sorry typo error. I meant the Gustard U12. I own the U10 and used it with the D18 with great results. I have no use for it any more as I don't need it with my current dac so if you want it send me a pm.

 

[Wynnytsky]

Yesterday a guy computeraudiophile listed a Yellowtec PUC2 (asking $225)
All you need is the $480 PUC2 lite, but you may as well get the full function unit if that's the price.
 
3 friends were using the Gustards (one preferred the U10 over the U12 for it's wider spread), but now they all use the PUC2 lite.  You can spend 4 times that and it would be a downgrade.
 
And let this guy build you the AES cable to your length (he calls it "Digital XLR")
http://www.groverhuffman.com/interconnects
My friend has the "Digital RCA" (with an XLR adapter on one end) and it's besting his favorite XLR cables.

 

[Jimbob Andrews]

Would this be a good dac amp for Alpha Prime?

 

[Jerryfan]

I've been using this thing day in and day out for 6 years. I have the urge to move on. I'm wondering what any D18 owner have upgraded to, and what the differences are.

 

[TT600R]

I own both A18 and D18, still no upgrade virus.
Very satisfied in combination with TH-X00.

 

[Galm]

I'm interested in the D18 but somewhat confused.
 
I have HD800SDRs and WA7 fireflies for the amp, but I want a smoother DAC than the WA7s.  I've heard from here that the D18 would do a good job with that as this:
“Neutral with a slight warmth, and musical, good build quality” “Fuses the usual strengths of the ES9018 DAC with a warmer, smoother tone than most - perfect for people who love vinyl or tube gear”
 
Sounds pretty much exactly what I'm looking for.
 
But I'm confused about a couple things.  This is getting old now, and grant fidelity seems to only have one left in stock?  Is it being replaced?
 
Also how does it compare with the DA8.  I don't really want the amp features of it, but I've read that it has a better dac than the D18?  
 
I guess any other recommendations if I want a smoother (and not brighter) dac?
 
Thanks in advance.