Bellarie VP 129 mod

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Ok No body got this schematic!!! So I started Oamp swap... (on red on the picture). I put 2 LM4562NA. The channel separation is amazing and the floor noise drop close to none.....

Next mod I wanted changed the coupling cap... And the other Oamp with the same LM4562NA.



I presume the coupling cap is one of those show on the picture.

1&3 10 uf
2&4 47 uf

Some one know.

ps: Is my first mod experience...
 

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I whant to change the coupling capacitor (C11, C22)
my choice is
Mundorf M-CAP or Elna Cerafine or Simlic II, any comments ... I know Black Gate but It's hard to find what we need..

And The c2 & c13 is suitable to chage for a better cap ?

And of course all resistors will be change for metal type 1% tolerance , PSU cap for Panasonic or Elna or Muse..
 
If I put the ba4560 in u1/u2 and lm4562 in u3/u4 position I got nice sound.

But

If I put the lm4562 in u1/u2 and the ba4560 in u3/u4 no sound comming from the preamp....

I will look futher in the in put circuit bettwen the buffer tube and the first amp.. I thinking about the imput impedance..

Do i need change someting to the design ? or try different opamp?

http://avforum.no/forum/attachments...llari-vp129.pdf
 
At this point I replaced my output cap with 4.7uf Mundorf M-Cap, 100uf Muse cap on c23 position (this change is amazing).

Ok in the pass day I read about opamp, thanks’ to TI documentation..

LM4562 is at the output stage. But I got to much floor noise... I read on some forum the LM4562 don't like big resistor as feedback.

So I was thinking to replace the original 47k on r32/r15 for 15k and the 4.7k at r31/r14 for 1.5k.

My only concert about this change is it will be safe? Because the +vb is in the entrance of the opamp. Please help me with this one.

And I need to add bypass capacitor on the lm4562 on the power supply. I will put 47uf like they show in the datasheet..
 
How's the headphone out on this baby?
If I were to make my brother a low cost system for headphones, would anyone recommend this as a great pre and headphone amp combo? I have a guy who can do the probably necessary mods...this'd be a great cost cutter for a modest system...lose the price of a component and a pair of IC's. Can they run, say, the sennheiser hd555's, lo-lo/med price audiophile cans. I don't love him that much.
dave
 
faxurda said:
sawp with LME49720 but the pre-amp stay silent.



No immediately obvious reason. It is much faster than the 4580 and PCB layout and PS decoupling may not be up to the task. You may try decoupling caps directly on the pins.

Again, i don't get it: why try to make a silk purse out of something like this? With very little effort you'll build a better phono stage from scratch.
 
For U1/U2 you need a FET input op-amp like AD8620 (w/adapter), OPA2134 or TLE2072A. I tried he OPA2134 and didn't like it either. AD is expensive, TLE cheap, both work. To use the 4562 for U3/U4 you'll need to reduce the +Vb divider resistors by a factor of 10 (same voltage, lower impedance). I added film caps across all the electrolytic filter caps. Specialty film and SILMIC II in the signal paths.
 
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