Aura Evolution VA100 • Clean up & upgrade

[Malefoda]

Hi there,
I've just been given an Aura integrated amp, wich was an attemp of B & W to sell electronic stuff.
I've also been given the matching CD player from Aura but it's more close to normal Philips' stuff and maybe it's just another Philips with a new shell. Anyway this CDP will also be cleaned up and some parts upgraded.
link to CDP upgrade: Aura CDP • Clean up & upgrade

It will be a good system to drive my Quad 11L as soon as I'll be changing speakers... maybe in many years

As far as I've read about it, it has a warm sound aimed to sound like class A amps. It's said to be a good sounding stuff with interest. Also got a phono preamp (also said to be good). Update: havin' an ear vs my current integrated (G&W TW-2006X) it's well balanced and warm at low volume, but lacking of space, details and a bit harsh.

Here is the amp:

Phono input:

Amp side:

2x BHC 4700µF 63V,
a single NE5532 in the middle (PS part or preamp part? ALPS pot is wired near this (black coax at bottom of the pic) so maybe it's preamp?). Still one LM4562 left if I replace the CDP's BB OPA2604.
a pair of these near the inputs or maybe just the phono preamp, with Nover 220µF/40V at their side.
Loads of MKC around, after the (phono) preamp for example.

So if some of you knows this little beat tell me more!
What may be changer after all these years? It's from 1992 from the PCB.
Or factory service manual someone?

Thanks,
Matthieu

[jacco vermeulen]

Originally posted by Malefoda
PS part or preamp part?

VA100 Evo-3, the NE5532=> power amp input.
Analog Guy posted a schematic of the Evo-2, is same same but with a 5534 single opamp per channel.

[Malefoda]

Found is thread, nice!
So the LM4562 there will do wonders. The PS line's caps may be upgraded there, do the big 4700 BHC caps deserve to be upgraded?
Any good choice instead of the 5534 at the phono preamp? The single LM4562 wich exists or not?
The sound here should stay warm for it will be a second background music system, if that helps in the choice of caps or such.
Thanks!

[aandy]

What does the opamp in the middle do?

[aandy]

If you replace the 2sj162 with Buz906dp and 2sk1058 with Buz901dp
this will increase the output current dramatically

you will need to increase the bius current slightly.

the next week link is the transformer,B and W used the cheapest toridal at the time and not one for good performance.

i Have a concerned about that opamp in the middle, what is doing as the VA40 did not use one and many people have reported that the VA 100 did not sound as good as the VA40.
No line buffer is needed to drive the power amplifier inputs.
so this will help make the amplifier sound Harsh along with to much negative feed back (making the amplifier over damped)

[Malefoda]

Hi Andy,

replace the 2sj162 with Buz906dp and 2sk1058 with Buz901dp

I won't go that far for now or maybe ever as it's not my main system and I just want to " release " the sound, and what you said is really what I feel comparing this to my main integrated, " a bit harsh and damped ".
Will have a fast try with the LM4562 as it's been said to do wonders as an preamp.

If any way to simplify that stuff and remove parts as it seems that preamp/buffer part can be taken away please let me know, and let me know how to do.

Thanks guys!

[aandy]

Yes the buffer does nothing.
I guess it was put there to reduce the sound quality by a person of limited knowledge.
just link it out.
you will have to take close ups of the pcb back so i can work it out

[Malefoda]

Ok I'll do that!
Jacco lonked this:
Aura Va100 Evoluton Ii
If that may help... mine shows "evolution 7" on the PCB.
There's a story of varying load or such...
Back with pics soon. I love removing, it's free!

[Malefoda]

The dead picture from the main post:

[aandy]

sorry if that is the circuit they used it will be very difficult to remove the oppamp.
and thats why it did not sound as good as the original

I can send you some pictures of the first aura amplifier if you want to post them.