Legato 3 - Look ma! No caps!

[Russ White]

I already comment on that in the manual. I would always use the buffers, because you have the greatest possible flexibility and there really is no harm.

It sounds like you have already formed an opinion though, so do whichever you prefer.

 

[crazyfrog]

Discrete parts for bal. to SE conversion

Hi Russ,

I'd like to have your suggestions for SE conversion in a "discrete way". Don't want to have a lot of negative feedback and high open-loop gain using an op amp. The legato output goes into my preamp. Many "discrete op amp" can be found here on this board but I'd like to get the maximum quality the Legato can give.

Thanks.

 

[BrianDonegan]

Hi Russ,

I'd like to have your suggestions for SE conversion in a "discrete way". Don't want to have a lot of negative feedback and high open-loop gain using an op amp. The legato output goes into my preamp. Many "discrete op amp" can be found here on this board but I'd like to get the maximum quality the Legato can give.

Thanks.

That would be Ventus

 

[SMathews]

So if I am omitting buffer and opamp SE/BAl stage, than J5 and J6 needs to be populated - right?

Should that be C5 and C6, as opposed to J5, J6?

SMathews

 

[BrianDonegan]

Nope, J5 and J6

 

[SMathews]

Thanks Brian. Time to get those glasses.

SMathews

 

[Spev]

Just to confirm, I have the board with buffers installed, but will initially omit the bal/se stage. Do I install J5 and J6? I'm assuming yes.

 

[BrianDonegan]

I would leave the jumpers out and just not power the bal/se stage (center power terminals).

 

[Spev]

Thanks Brian. Glad I asked now.

 

[thomaspf]

Buffer or no buffer?

Hi,

I am working on my next Buffalo project and would like to try out the new Legato stage. I am building an integrated box with a β24 amplifier that has an input impedance of 5000 Ohm.

For that fixed configuration what is the recommended setup. Buffer or no buffer?

Cheers

Thomas

 

[crazyfrog]

That would be Ventus

Thanks.

Could I use The buffers output of the Legato to feed a headphone and use the balanced signal output for the Ventus (or other discrete op amp) at the same time?

 

[avr300]

Sure you can

 

[BrianDonegan]

You could even use only the Ventus' discrete SE output to feed both at the same time.

 

[regiregi22]

That would be Ventus

I am comparing the used buffer (LM49600) against the one I used in some projects (BUF634T). Looking at the circuit diagram they LOOK THE SAME, but they are different manufacturers.

Why did you choose LM49600, any advantage I didn't see?

 

[BrianDonegan]

The LME has slightly lower noise density numbers and is a bit less expensive. I would not say there is a huge difference between them, however. Russ might have more to say on it.

 

[Jean-Charles]

I would leave the jumpers out and just not power the bal/se stage (center power terminals).

Hello Brian.
Not to sure I understood well. I too would like to use the SE output available at J5,J6 and not power the buffers. Since IC1 takes its power from +15V3 and -15V3, thus center power terminals, I would need the jumpers at all times. There is no way to unpower those buffers easyly, that I saw.
Could you clarify, please.

 

[BrianDonegan]

Hello Brian.
Not to sure I understood well. I too would like to use the SE output available at J5,J6 and not power the buffers. Since IC1 takes its power from +15V3 and -15V3, thus center power terminals, I would need the jumpers at all times. There is no way to unpower those buffers easyly, that I saw.
Could you clarify, please.

That's a different proposition.

I have the board with buffers installed, but will initially omit the bal/se stage.

He was not using the bal/se section at all.

You are correct, that it is not straight forward to not power the buffers. However, why do you want to avoid using them is they are already there?

 

[Russ White]

If you want to *not* power the BAL/SE stage (including the buffers populated or not, it won't matter) yet still use the balanced I/V stage you you simple omit the supply jumpers and wire both the left and the right side terminal blocks directly to your power supply.

This IMO is an extremely impractical thing to do. Instead go ahead and populate the BAL/SE stage and power it, but either use i's output or not. your choice. Its presence does do harm.

 

[Russ White]

The buffer and the op-amp are one loop. You cannot really isolate them with removing the buffer from the equation. As I have said multiple times - if you have the buffer, it is only ever a *good* thing. If you don't want to use the buffer order the version with out it. Simple as that.

 

[Russ White]

I am comparing the used buffer (LM49600) against the one I used in some projects (BUF634T). Looking at the circuit diagram they LOOK THE SAME, but they are different manufacturers.

Why did you choose LM49600, any advantage I didn't see?

They are both good, and yes they are quite similar, but I simply like the National part better for the reasons Brian stated, plus it seems to do a better job dissipating heat.