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W A R N I N G !

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Tuesday, July 22, 2008

Small Zhaolu D2.5 mods...

I was bored and couldn't wait for the LM4562s to arrive, so I took apart my Zhaolu ahead of time and proceeded with some small mods:

Here is the list of mods to be done:

1. Fixing grounding issues
2. SPDIF transformer coil
3. Shorting output caps
4. Staples on crystal (lol...)
5. Disconnecting the headphone amp
6. LM4562/OPA2107/2132/2134
6a. AD823
7. Belden 1694A
7a. Belden 89207/89259

Without purchasing any extra material, I proceeded with 3 and 4.

I didn't want to resort to soldering, because that is irreversible (well.. semi), leaves and ugly mess, and I do not have a good soldering iron.

So an idea struck me and come a fixer's best friend: The Blu-Tack

Although it is called Blu-Tack, mine is white in color.

Why Blu-Tack? It is elastic and hence has more holding strength than silicone and tape. Furthermore, it's very to clean up and leaves no trace whatsoever.

But, without using solder, there's the problem of bad connection. How will that affect? I'll find out soon.

So, about half of my remaining 15cm or so of Belden 16AWG is sacrificed for this job. Boy they are tough to bend, real thick solid copper strands.

I also used the Blu-Tacks to surround the clock crystal with a bunker of staples. That should give it a bit of shielding. Shouldn't have any negative effects.

And the first thing I did after opening the casing was to disconnect the headphone amp. It is supposed to make the power supply cleaner, but I did it also because it was heating up in the system.

The immediate audible effect: Treble is... I dunno... more harsh but at the same time more clear with more details, but somehow I can feel that more notes are missing, and the instruments sound smoothed-out. Either my bad connection has killed the high frequencies, or it is a combination of the bad effects of the OPA2604's poor quality and typical Burr-Brown laid-back sound, and the poor high-frequency performance of my subwoofer + speakers setup. Perhaps the soon-to-come LM4562 and amp + speaker upgrade will solve the problem.

Another thing is that there are a few more instruments at the highs that can now be heard. That is an improvement I hope, at the expense of lowered smoothness, soundstage (air?) and high harsh, yet somehow it feels a tad more natural. Why the soundstage is reduced beats me.

EDIT: I realize why it sounds more natural yet has less air. It's less warm now, and the instruments are right where they should be. In short, it's more accurate, but I think I prefer the warmer, more spacious, laid-back sound. Have I reached my max in audio detail enjoyment? and focusing on the sound signature that I like instead.

Another distinct and good improvement is the lows response. The bass is more punchy, and it extended downwards by half a note more. The bass drum now sounds more like a real-life bass drum. These are expected improvements from shorting out the output caps.

Overall it has more goods than bads but I'm not used to the sound. After a while I'll get used to it and there's no turning back, as usual. The instruments definitely sound more real. Though I'd love it if the soundstage didn't become smaller.

But the bass... this is reminding of the Belden cables, but this case it's more punchy than mid-bass heavy. How, my subwoofer dial is already at 3/10 and too much deep bass is bad for my tinnitus.

I also wanted to fix the grounding issues while I'm at it, but couldn't find out where exactly to connect the wires, so had to abandon that for now. Else it would've been a small improvement without negative side effects. I know there will be an audible improvement coz the standoff-to-standoff through the chassis resistence is very significant. It was 1ohm or 0.1ohm, can't remember, but those are high values nonetheless.

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