confused about unbalanced/balanced

[roger-k]

Now I have made-up the PCB for P1,7 so much soldering remains.

I have read a lot of unbal/bal in many forums here, but I'm still confused about balanced inputs since all of my sources not have balanced outputs. I know it is just to short the negative input to the ground, but when I do this:
Will I still use the whole amp or just the "half"?

 

[john-china]

because another half is fuctional , it can affect whole circuit.

you can still use whole circuit

 

[flg]

It depends on your input following the pre... The use of balanced as much as possible is bennificial. The 1.7 is very good at converting S.E. to balanced. If you drive a balance Pwr Amp input you would get good results If you are not, I'm not sure you will be much better than BOZ

 

[roger-k]

OK....
One reason for the confusing is this:
http://2bak.homepage.dk/mybosoz.gif

Is this right? I think there is one stage on the left side and one on the right side of the schematic. Both are inverted so the input - is going to be the otput+ and vice versa.
Am I right?

If I'm not right, what is meaning with Q2, it vill never be trigged.

 

[flg]

I see
Well, I think that removing the load components of the unused output may alter performance in a negative way
Like I said before though, I'm not sure there is much benifit to the BOSOZ with S.E. input and S.E output
You may experience less 2nd harmonic distortion than the BOZ though, due to the differential function still contibuting somewhat

 

[Babowana]

Both are inverted so the input - is going to be the otput+ and vice versa.
Am I right?

I think that unbalanced-in and unbalanced-out of BOSOZ would keep the 2nd harmonics that BOZ has. And, compared with BOZ, the benefit is that we could have better symmetrical sine waves of output signal swing.

And, +in sees +out . . .

If I'm correct, Papa . . .

 

[GRollins]

Actually, the idea of using a differential like that is just peachy. Like a cascode, a differential renders the capacitance of the input device moot.
The input device is essentially used as a follower. Since the Source tracks the Gate pretty much one for one, you're not trying to charge/discharge the various capacitances of the input device. The ouput device delivers the voltage gain. Since it receives its signal via the Source you're in a whole 'nother realm as far as what capacitances are being charged and discharged. The cool thing is that the "follower" front end can supply all the current you might need to drive the other device.
It's non-inverting, which is always nice.
Note for the record that this is a case where I would probably use a CCS to bias the thing, even though I usually approach current sources with caution.
In short, yeah, it'll work and work well if properly executed.

Grey

 

[Babowana]

Like a cascode . .

Yeah, slipping through the fingers of the blood-sucking capacitance . . .
Your short writing always bring me better understanding . . . thanks.