Phase Inversion Switch Circuit

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80hinhiding said:
How could the following be represented/achieved in a bare bones discrete component approach?

http://sound.whsites.net/p107-f2.gif

A single phase splitter?  I've tried that but not had success with it yet.  I'm looking to do a low component count phase inversion switch and want the positive and negative output to have been affected by the same amount of circuitry/noise etc.  I don't want to flip one and have it be a slightly noisier version, if that's possible.  Ideally I'd like the signal not to be affected at all by the inversion stage but realize that's probably impossible with an active, unbalanced switching.

Dealing with mono.

Adam

why opted for a circuit when you can achieve the same thing with a DPDT switch?
 
80hinhiding said:
How could the following be represented/achieved in a bare bones discrete component approach?

http://sound.whsites.net/p107-f2.gif

A single phase splitter?  I've tried that but not had success with it yet.  I'm looking to do a low component count phase inversion switch and want the positive and negative output to have been affected by the same amount of circuitry/noise etc.  I don't want to flip one and have it be a slightly noisier version, if that's possible.  Ideally I'd like the signal not to be affected at all by the inversion stage but realize that's probably impossible with an active, unbalanced switching.

Dealing with mono.

Adam

That circuit for mono has essentially five components - 1 x Opamp and 4 x Resistor. How low a component count do you want ?
 
80hinhiding said:
I would do that with balanced input, but I'm also dealing with unbalanced input so I was looking for a solution to handle both.

A

use an inverting unity gain buffer op-amp to flip the polarity of an unbalanced signal.
you can omit the input and feedback resistors.
just tie the negative input pin to output pin, and the positive input pin to ground.


 
80hinhiding said:
Yes I know.  However,  the opamp has many components inside it.

Adam

Op amps can be quite good.

Maybe give it a shot and see if it works for you. I think if you pay attention to the details, you can get pretty transparent results. 

Transformers can be used to invert  but, we know those can be not so transparent although I hear the Jensen ones are nice in this regard???....

You should be using tubes anyhow....lol

Very interested in this.....

Good Luck!
 
There are many option here, I do like the idea of a single inverter and just bypassing it if you don't use it (unless you do need the buffer for some reason). If there is noticeable noise or distortion in that single inverter it means it's not well designed and you should go for another option.

As I said, you could want to keep the buffer, with a SPDT per mono channel you could use a input resistor  to the inverting input and swap to which input it goes, you still need the DC path to the non inverting, you should use 22k directly from ground to non invertning input. Might not be the best solution for noise but your's isn't either, as you keep a higher noise gain than you need when non inverting and the 22k in series with the input. In mine there is the floating resistor which is not optimal (when used as buffer) and non inverting input not shorted to ground (when used as inversor)

With a DPDT per mono channel you could do a lot, keeping optimal performance in both polarities.

Note: decoupling should go to ground (at least in unbalanced outputs, if you use active differential outputs it just might make sense having rail to rail decoupling)

JS
 
joaquins said:
Note: decoupling should go to ground (at least in unbalanced outputs, if you use active differential outputs it just might make sense having rail to rail decoupling)

JS

I can't say I've found that to be the case wrt hf decoupling at the ic. Or measured any problem with 'across the rails' decoupling.
Would be interested in any problems ?
 

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