buffer with balanced output

[udip]

Hi all,


I'm looking for a simple discrete line buffer, that could be
direct coupled, could drive 1k load, and most important,
that will have balanced output.

I was thinking about borbely fet buffer (figure 15c in JFETS 2
article on his website), since in theory it has zero offset.
Can I get balanced output from such a simple circuit, by
taking the cold output from a resistor in series with ground?
(I think that most important thing in balanced lines is that the
reciever should see equal impedances at both inputs),
And if so, what should be the resistor value?



Thanks in advance,

Udi.

 

[udip]

Does anyone know a good discrete buffer with balanced
output?

 

[udip]

Hi,


Borbely has a balanced line amp design, and I wonder if
I could use feedback in order to control gain.
The problem is that it's balanced, so I don't know exactly how
to do it.
Maybe I can use two feedback paths, from outputs
to inputs? Any ideas?


Thanks,

Udi.

 

[Leolabs]

Not sure what you request is.Is it balanced in/balanced out OR unbalanced in/balanced out???????

 

[thanh]

Hi!I like balanced in/balanced out

 

[udip]

Not sure what you request is.Is it balanced in/balanced out OR unbalanced in/balanced out???????

Hi,


I'm looking for a buffer with unbalanced input and balanced outputs. If it haz balanced input, that's ok, cause I can always tie one input to ground.

The problem I have is how to control the gain in the circuit,
because it's unknown to me... I need gain between 0-6 db...


Udi.

 

[udip]

How about this circuit? will it work?

 

[darkfenriz]

cenrtailnty, but without dc-feedback

 

[udip]

cenrtailnty, but without dc-feedback

Sorry?

 

[Leolabs]

Absolutely no!The COLD end would be appear like the input of a power amp grounded!

 

[Leolabs]

thanh's request makes thing easier,just build two identical buffer for each phase!


try this: www.borbelyaudio.com for JFET buffer

 

[udip]

Absolutely no!The COLD end would be appear like the input of a power amp grounded!

What power amp?!!?!?!?? what power amp grounded??!?1?!?

 

[Leolabs]

I assume that the buffer outputs are connected to a power amp(or other equipment)As the outputs are conected to any equipment's inputs,then i consider the buffer's outputs=other equipment's inputs.
Get the picture????

 

[udip]

I assume that the buffer outputs are connected to a power amp(or other equipment)As the outputs are conected to any equipment's inputs,then i consider the buffer's outputs=other equipment's inputs.
Get the picture????

The COLD does'nt have to carry any signal.
In balanced operation it's important that both lines
will have same impedance..

Udi.

 

[Leolabs]

No.The COLD must carries signal too,then u call it fully balanced.The HOT carries the in-phase signal while the COLD handles out-of-phase signal(180').If the COLD aint handles anythin or shorted to GROUND,then the whole thing just a normal unbalanced configuration!

 

[udip]

No.The COLD must carries signal too,then u call it fully balanced.The HOT carries the in-phase signal while the COLD handles out-of-phase signal(180').If the COLD aint handles anythin or shorted to GROUND,then the whole thing just a normal unbalanced configuration!

I think you got it wrong... look at this link , page 3.

Udi.

 

[Alcaid]

udip: I think you are wrong, they both carry signal, but 180' out of phase:

 

[udip]

They both carry signals in relation to each other,
but relative to GROUND only the HOT carries signal..
Thanks for the simulation, though.

Anyway, the point was that the circuit I posted is working OK.


Udi.

 

[richie00boy]

The participants of this thread would do well to read this:

http://www.dself.dsl.pipex.com/ampins/balanced/balanced.htm

 

[udip]

BTW, Alcaid, you forgot connecting the two 100k res to ground