The best sounding audio integrated opamps

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Mooly

Mooly

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Hi Andrea... the upc4570C in your Pioneer looks a likely candidate for an upgrade, having looked at the data sheet.
Is that something you might consider ?

The feedback around that opamp is quite unusual in it's implementation, taking DC feedback via the 820k and AC feedback via the driver and output stages via R312 and R304. Also look how low R302 is.
You also have a mute transistor Q304 (like many CD players in it's implementation).
That may be used just for a "soft mute" when changing inputs etc as the main outputs (speakers) have a relay delay....
There are more electrolytics too that see audio across them in the power amp stages.
 

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Mooly

Mooly

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Joined 2007
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Dissasembly of most gear like this is usually staightfoward, just a lot of screws and plugs/sockets etc.
If you are not sure you just write it all down (and take pictures) as you go along.

That said look at page 28 in the manual... doesn't the bottom come off so it can all be worked on without pulling apart.

That said don't go and break it :)

It would be an interesting exercise to tweak though... and fit a socket for the opamp.

If you are happy that is all that matters :)
 
A

Andrea:

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Joined 2009
QSerraTico_Tico said:
Try this one:
YD2200 顶级å�Œè¿�放|丽特音å“�|LITE AUDIO 丽特音å“� 国内最大的音å“�DIY 零é…�件供应商，为您æ��供一站å¼�çš„è´*物体验ï¼� - Powered by MvM mall
Click to expand...
Is it a relative to the DY2000 in some way? I have two of those - didn't like them too much, but I might try them again.
 
A

Andrea:

Banned
Joined 2009
Mooly said:
Dissasembly of most gear like this is usually staightfoward, just a lot of screws and plugs/sockets etc.
If you are not sure you just write it all down (and take pictures) as you go along.

That said look at page 28 in the manual... doesn't the bottom come off so it can all be worked on without pulling apart.

That said don't go and break it :)

It would be an interesting exercise to tweak though... and fit a socket for the opamp.

If you are happy that is all that matters :)
Click to expand...
I'm happy because I'm not 'expecting the moon' from it :) and because it has got a pleasant and detailed sound which never gets tiring. Sure, it's not the last word in transparency... but all it does, it does well.

Hmmm...let me look at the manual...:D
 
A

Andrea:

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Joined 2009
Mooly said:
I can list some simple mods if you like... components to perhaps change... I'll leave it too you what you fit quality wise.
Click to expand...

If you don't mind...thanks, so we'll see if you come up with something similar to what I already have in mind. However, I don't know when exactly I'll get around to doing it, since in this period I'm a little busy with study.


BTW... why not just make it into a power amp by isolating one of the RCA inputs & connecting them to one side of C301 (of course I'd replace the cap)? I could momentarily use my 24V CMOY as the preamp. Sure, that way the opamps in the signal path would become two.
 
Mooly

Mooly

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Have a look at these, other channel in brackets.

Main PCB

C319 (C320) 10uf 50 volt...

C317 (C318) 10uf 50 volt...

C305 (C306) 10uf 50 volt... important quality wise

C301 (C302) 10uf 50 volt... important quality wise

IC301 opamp :)

Is that mute transistor/s really needed... ??? It would be the first thing to go in a CD player.

Volume PCB

C513 (C514) 10uf 50 volt... important quality wise

C516 ----- 33uf 25 volt... use 47uf... important quality wise


Tone control

C755 (C756) 10uf 50 volt... important quality wise

C763 (C764) 0.1uf 50 volt... confirm value ? use poly ?

C759 (C760) 0.47uf 50 volt... confirm value ? use poly ?

IC751 opamp :)
 
A

Andrea:

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Joined 2009
Actually, if you look closely you'll notice that in the volume assy in "direct" mode the signal doesn't pass through any capacitors. The inputs/outputs are in the bottom connector in the schematic.

I did check this better because I saw that those two 10uF in the "volume assy" are not Nichicon Muse... and of course I knew from what I'd experienced that DC offset in the CD inputs could reach the volume pot freely.


So... there are only 4 10uF 50V Nichicon Muse FG in total, and they're located in the main pcb: C301/302 and C305/306. Besides, there are two larger Nichicon Muse's but these must be on the opamp's power supply lines.

Those 4 10uF caps are all that I'd bypass with Wima MKP's. In fact, directly in the signal (meaning not feedback signal) path there's only 1 electrolytic... and it hears.

I'd tried a Nad C320 some time ago, which I'd also opened up just to find that in the preamp section it had like 7 no-brand electrolytics in the signal path... no wonder it didn't sound very subtle... :)
 
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A

Andrea:

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Joined 2009
Regarding the muting transistors... I wouldn't want to find myself with pops when changing source and such. Besides I'd tried this little tweak in an older Super Pro DAC and the difference was...none.


Soo... it comes down to changing opamp (probably I'd try LME49720HA/LME49725/OPA827), plus bypassing those 4 electrolytics, plus adding a couple of 100nF Wima's on the opamp's power supplies (just for peace of mind), plus maybe replacing that 220pF cap in the inputs of the opamp with Wima FKP2.

Doesn't look too complicated :)
 
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A

Andrea:

Banned
Joined 2009
And what If I just saved up for something like this:

Welcome to Audiophilechina


I don't need much power as my room is 16mq and I'm not a heavy metal freak :)

Mooly...what do you think of it?


Someone told me that the diode bridge of this amp is only rated 3A... is it undersized? Or is it OK?

The input caps are those yellow polyester's... well, no big deal. In case I wasn't 100% happy with the sound, I could replace them, or bypass.
 
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