Does the review of the Gustard X26 pro have incorrect info regarding Op Amps ?

[restorer-john]

I'd be more concerned with the atrocious soldering of the 'K2' clock...

Looks like it was a back of the shop dealer "option"

JVC have long (since 1987) championed their own K2 technology. Gotta love this explanation.

https://www.jvckenwood.com/en/technology/k2/what-is-k2.html

 

[Cut-Throat]

I'd be more concerned with the atrocious soldering of the 'K2' clock...

Looks like it was a back of the shop dealer "option"

Mine does not look like that.... That may have been a 'one-off' sample or something.
Mine looks exactly like this one.

 

[kopczas]

https://www.jvckenwood.com/en/technology/k2/what-is-k2.html

So is K2 upsampler basically ?

 

[taner]

I also noticed those opamp look like devices but I think that they are not on signal path or they are not opamps because at least 4 of them needed for each channel if they were on signal path. Each ESS9038PRO chip has 8 individual outputs which means it requires at least 4 dual opamps for each channel for I/V conversion.

 

[taner]

I think that they are not on signal path or they are not opamps because at least 4 of them needed

...unless they are served as differential amp/buffer after discrete I/V stage.

 

[JohnYang1997]

...unless they are served as differential amp/buffer after discrete I/V stage.

They serve as input stage for the i/v stage and discrete components forms a buffer in the loop of the opamps.. And you can simply parallel connect every other two together. It is not needed to i/v each output separately.

 

[taner]

They serve as input stage for the i/v stage and discrete components forms a buffer in the loop of the opamps.. And you can simply parallel connect every other two together. It is not needed to i/v each output separately.

You are probably right. Is there any thread that you were discussed x26pro's analog section? How did you get that information? Are you aware of which opamps were used?

 

[JohnYang1997]

You are probably right. Is there any thread that you were discussed x26pro's analog section? How did you get that information? Are you aware of which opamps were used?

I get that by just looking at the PCB. It's quite straightforward.
Some more verbose reasoning:
To achieve this level of performance you need lots of gain and thus feedback. The only thing that has both large amount of gain and low noise input stage is the opamp. My guess is opa1612. If not then ada4898-2. There's no other option that I know of.
It's in fact a good idea to use opamps. There's nothing wrong with it.

 

[taner]

It's in fact a good idea to use opamps. There's nothing wrong with it.

I agree but if they were not biased for Class-A, signal chain will not be fully Class-A.

 

[JohnYang1997]

I agree but if they were not biased for Class-A, signal chain will not be fully Class-A.

I wouldn't think twice about class A. It's almost never true class A when manufacturers specify it.

 

[bob7296]

Yes, it seems that Sanu was mistaken when he said the output stage was a discrete component class a topology. It in fact shows an 8 pin op-amp IC in each output amplification stage. This has no affect on his opinion on the way he feels it sounds. Most likely a discrete class A output stage would sound better than an IC. This is one of Burson Audio's specialties, in making 8 pin dip drop in replacement discrete op-amps. The output low pass filter does show discrete circuitry, and they are using quality WIMA film capacitors, which are known for their good sound. I take his word for it, that it sounds good. That's all we can do with these reviews. I know Electrompanient uses full discrete class A circuitry in their CD and DAC products, and you pay for it...

 

[sarumbear]

Mine does not look like that.... That may have been a 'one-off' sample or something.
Mine looks exactly like this one.

View attachment 137237



View attachment 137236

He must have a Monday morning unit…

 

[bob7296]

He must have a Monday morning unit…

Here are the op-amps in the circuit shown in the white circles...

 

[sarumbear]

Here are the op-amps in the circuit shown in the white circles...

I think you replied to the wrong person