Mods: We need a new section in this thread for the D1+ ... it's a whole nuther aminal!
Short answer ... the D1 is NOT upgradable.
Short answer ... I for one couldn't resist. <G>
Got my shiny new D1plus the other day and have around 30 hours on burn in. Basically fired up a playlist in jRiver and have had that pushing tunes for maybe 6 hours a day. Several listening sessions logged also.
Using the New! Improved! Tenor USB stage, the sound is already crisper than that of the D1. Soundstage isn't what I'm used to, but that figures, as the D1+ is currently running the stock Chinese 6N3 tube and the basic op amps. I plan to burn these in for maybe another 50 hours just to see what they can do, then swap back to the D1 w/upgrades for a head to head. That's currently got the OPA627 op amps and a 1972 JW series WE2C51 tube ... my favorite. Do a couple swaps to get a feel for the differences, then switch the WE tube into the D1+, try that, then swap the OPA627 op amps in for the full effect. From what I've already heard from the Tenor USB upgrades already, I expect to be suitably rewarded for my efforts.
Worth mentioning - this is my first experience with the Chinese tube and standard op amps as I ordered my D1 with the upgrades installed. The D1+ started out down around 5db from the D1 (with the OPA627s and WE2C51). After around 20 hours, it began to pick up and is maybe 2db down now. Should be interesting to see when and if that levels off. Also, the WE2C51 is a hotter tube on output, so it's not surprising the 6N3 is having trouble keeping up.
PS ... anyone out there contemplating the TubeMagic or similar tube DAC, DO consider some tube swapping. Very important and noticable differences in performance and output from tube to tube. Don't ask me how I know ... <G>
Yes ... I know ... I have a problem. ;-}
In the case of the current Chinese 6N3, it's got a very respectable sound (if a bit thin in the mid bass compared to my premium tubes), but there is a bit of ringing in the high registers with a hard load. That's a fairly common complaint with this tube. The ringing does tend to calm as the tube breaks in and gets some miles on it. The JW, 5 Star, and other such "military grade" tubes don't have the problem as they've got major reinforcement in their design to eliminate resonance and noise. More micas, improved damping, heavier components, better wire, etc ...
OK ... I promised pics ...
The original D1:
<< High res pic HERE >>
The new D1 Plus Edition:
<<
High res pic HERE >>
Lots more changes inside the box than outside, which is why the D1 is NOT upgradable. Full redesign on the USB section of course, and there's a whole lotta tweaking in the pre section also. Major change in the addition of a third op amp that I'd think offloads common functions and timing from the channel specific op amps to improve isolation and allow those to concentrate more on the detail. Power looks about the same. LOTS of surface mounting replacements for what were once conventional components, so probably less attractive to the tinkers amongst us. Some value changes on common components, I expect based on real world performance and user feedback. Some position swapping about on the board Example: relays for soft switching relocated to the back of the main board instead of on the control daughter board. This seems to have calmed the POP when changing inputs on the fly - I'll still turn speakers off before doing that as it's more or less habit now, and I'm running low on fuses for my tweeters. Also, major streamlining in the signal path with the elimination of the BYPASS switch AND volume control in the DAC signal path. The volume knob is strictly for the headphone jack as shipped, but I'm told there is a way to add the volume control back for the DAC with a couple wire swaps if necessary. I always ran mine on bypass anyway, so doesn't affect me at all.
The case is identical except for the faceplate, which is a good think for a habitual tweaker like me. The cover has always been a PITA to remove, and if anything the one on the D1+ is even tighter. I ended up cutting the bottom flange off the cover on my D1, and it slaps right on the D1+ ... joy!
Here's a potential deal killer for many ... they moved the print on the selector dial closer to the knob. Oh noooooooOOOOOoooos ...
Anyway ... I'm going for longest post of the day here ... what do I win??
PS ... anyone with a D2, feel free to post up pics for comparison ...
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