[Leo V]

UPDATE: I just downloaded NC650V's schematics, and posted them here:
block diagram (71KB)
detailed diagram (288KB)
full schematic (419KB)
As you can see, there are a couple differences from NS500V! Any observations? I removed the correct muting transistors (Q214 and Q215), but I hear no power on/off transient sound. Could that be good luck?
---------------------------------------------

Well, I have only the NC650V, but since it's the carousel sibling of the NS500V, the discussion will benefit from both.

My question: are there any mods that I can do myself to improve sound quality? I have some non-audio modding and soldering experience, for background. I am a college student--no extra money to pay someone else to mod my unit. So my budget is:

1) $30-60 at most in parts
2) these two hands (+soldering iron, wire, etc.), and
3)

enthusiasm

Setup: Swan Diva M-200 speakers and DIY silver signal tape

So far, I have found this thread on NS500V modding... having looked through it, this thread has very useful information I'm still digesting. My main problem will be that my NC650V should have slighly different design.

Any suggestions or links welcome!
--Leo

PS: If it helps any, I've posted some under-the-hood photos of my NC650V:
top view 1
top view 2
open tray view 1
open tray view 2

 

[Budgie]

The simplest mod with the biggest bang for the buck is to eliminate the output coupling caps (if possible), or to upgrade them if they can't be eliminated. You will need to be able to find them, and measure for dc voltage on the opamp side of them to determine if they should be removed or upgraded. The next upgrade would be changing the output opamp to a better chip. Since your cd is a newer model, it uses surface mount chips. Replacing them is a pain, if you never have done it before, and is not for the faint of heart. Also, any time you decide to mod something, you run the risk of it going up in smoke. If it dies a horrible death during this process, can you replace it or live without it?

 

[puppyslugg]

Check out diyaudio:

http://diyaudio.com

And audioasylum.com:

http://www.audioasylum.com/audio/tweaks/bbs.html

 

[Leo V]

I've already fried my videocard once--ironically, after having successfully modding it by shunting a surface mount resistor. I was being sloppy afterwards and shorted some pins with my multimeter! My point is that I accept the risks involved

So my first questions are:

1) How to locate the coupling caps? In the sibling NS500V, they look like surface-mount parts, as the thread I linked shows. Have multimeter, willing to use

Must I order Sony's $30 service manual?

2) How to locate the opamps? I'm measuring DC voltage between which two points? How to determine (from the results) whether the coupling caps can be bypassed?

Once there, we can discuss replacing the opamp

My questions are dumb, but every audio modder was a newbie sometime, right? If I succeed (or fry the unit) I'll try to contribute with pics of the results!

Thanks very much,
Leo

EDIT: puppyslugg, would you suggest posting there (or DIYaudio forums) instead? I've already seen this thread as you've linked it, so it's currently my "map" of things to do.

 

[puppyslugg]

Your questions would be answered more easily with a schematic. Quite frankly, for me, it's an necessity. You can mess around with back tracing the circuit, but that's a hellava lot of work. Post at the links, and maybe someone would email you a copy of the schematic. Worth a try. In the case of the NS500V, at least the schematic are available and would be worth buying one if need be. A schematic would make your life a lot easier. I've been searching for a schematic for my AMC cd8b for quite awhile without much success. AMC is so tight with with supplying schematics, and I was more than willing to have paid for it, too. Sucks.

Good luck.

 

[Budgie]

Crap, I just typed for 10 minutes then made a bad keystroke and it all went bye bye. I hate computers.

 

[Leo V]

Quote:

Originally posted by Budgie Crap, I just typed for 10 minutes then made a bad keystroke and it all went bye bye. I hate computers.

Man... I wonder what you had to say now... I try to select the entire message & copy it before submitting.

However, I believe I successfully found the evil caps! They're the same numbers as in the NS500V in my link from the original post. (the DIYaudio thread). I've just removed the caps, and I'm about to solder silver wire between the contacts! The DC voltage offset was only .001-.003V, so we'll happily do without the caps.

*praying to electronics gods while the soldering iron warms up*

 

[Leo V]

By golly, it still works!

Unfortunately, my speakers aren't here yet so I'm using Diamond RIO earbuds... try using these to measure sound quality

My question so far: was it a good idea to use thin (30-gauge) pure solid silver wire for connecting the ousted caps' contacts? I used about 4mm-long segments for replacing each cap. Should I have used thicker wire, or does it not matter?
--Leo

PS: Many thanks for the advice! I am going to post on DIYaudio as well, for info on additional tweaks. Now I'll need a bit of help with the opamp. 4558 Opamp, you are next!

 

[braillediver]

I can email you the schematics for the NS500V if you want? It’s 385K.

Have you dampened the chassis?
Improved the isolation by using new feet or putting it on sandbags?
Have you done anything to make the chassis more rigid?
Sandbagged/dampened the crystal?
Changed the power supply diodes to UF400(?) at least?
Blue tak the transport assembly to dampen it?
What type of interconnects are you using?

There are a lot of tweaks you can do without solder right off the bat. How old is the player? It’s recommended letting it burn in for a few hundred hours.

Ideally you would do a specific tweak and analyze the results. Let it burn in then do another tweak. This way you can see if the tweak actually did anything and if you like the results. You shouldn’t try to do the most mods; the goal should be the best mods. You’re trying to improve the sound not modify the player.

Until you establish a baseline, modifying the player is a crapshoot. You need to set the system up initially well, the new speakers, speaker cables, interconnects and speaker placement to start with before modify the player. Get some CAT 5 cable and braid some speaker cables.

Slow down and listen to the music.

The guy I got the schematic from destroyed his new player in less than a week. He shorted some parts because he was in a hurry and then trashed the PCB.

Enthusiasm is great but knowledge is King.

 

[Leo V]

Quote:

I can email you the schematics for the NS500V if you want? It’s 385K.

I have the NC650V, but the 500 schematic could still be useful! If you can, my email is leov (at) wam (dot) umd (dot) edu. Thanks!

Now as to your suggestions, I'd like to know which make the most difference...
Quote:

Have you dampened the chassis? Improved the isolation by using new feet or putting it on sandbags? Have you done anything to make the chassis more rigid? Sandbagged/dampened the crystal?

braillediver, could you please explain how each of these is done? How much of a difference does it make? Currently, my player is resting on the carpet.
Quote:

Changed the power supply diodes to UF400(?) at least?

Again, could you please explain how this is done, and what it accomplishes? Do you know of any NS500V/NC650V owners who successfully modded their PSU this way? Modding the power supply is pretty serious business...
Quote:

Blue tak the transport assembly to dampen it?

Same question! How, and why

Quote:

What type of interconnects are you using?

I'm constructing silver signal tape

Thanks for the feedback!
Leo

 

[Budgie]

Cool, Leo. I think that getting rid of those caps is the single biggest improvement I was able to make to my player. Other improvements helped, but not as much. The jumpers you used are excellent. The power supply diodes are another option, but the complexity goes up a bit. I would be patient till the speakers show up and you can do some serious listening.

 

[Leo V]

I just removed what I believed were the mute transistors: Q214 and Q215 as seen in the picture. However, to my surprise I didn't hear any power on/off transients! Just same normal operation. Any way to explain this?

So Budgie, have you actually messed with the PS diodes yet? I don't mind complexity so long as someone else tells me what to do

 

[Leo V]

Update: I ordered both Analog Devices AD8620 and Burr-Brown OPA2134 samples directly from the manufacturer. Any opinions on which is better for a NS500V/NC650V?

Also, I found Holco resistors (for bypassing the output resistors), over here. Should I get the 45-Ohm 1/4-watt resistor (part H8-45.3 near the top)? Sorry if it's a stupid question, I am new to audio modding!

Leo

 

[puppyslugg]

Quote:

Originally posted by Leo V Update: I ordered both Analog Devices AD8620 and Burr-Brown OPA2134 samples directly from the manufacturer. Any opinions on which is better for a NS500V/NC650V?

No contest: ad8620. But if you use a socket, try both. Are you planning to bias them class A?

 

[Leo V]

Quote:

Are you planning to bias them class A?

I hear the term a lot, but what does it mean? Any instructions for that?
Thanks,
Leo