80hinhiding

Phase Inversion Switch Circuit
« on: November 14, 2017, 07:46:28 PM »
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
« Last Edit: November 14, 2017, 08:50:44 PM by 80hinhiding »


Re: Phase Inversion Switch Circuit
« Reply #1 on: November 15, 2017, 06:04:49 AM »
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?

scott2000

Re: Phase Inversion Switch Circuit
« Reply #2 on: November 15, 2017, 06:12:11 AM »
why opted for a circuit when you can achieve the same thing with a DPDT switch?

You mean to flip between transformers or something?

80hinhiding

Re: Phase Inversion Switch Circuit
« Reply #3 on: November 15, 2017, 07:34:06 AM »
why opted for a circuit when you can achieve the same thing with a DPDT switch?

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

Newmarket

Re: Phase Inversion Switch Circuit
« Reply #4 on: November 15, 2017, 08:05:14 AM »
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 ?

Re: Phase Inversion Switch Circuit
« Reply #5 on: November 15, 2017, 08:10:41 AM »
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.


« Last Edit: November 15, 2017, 08:16:30 AM by metalb00b00 »

80hinhiding

Re: Phase Inversion Switch Circuit
« Reply #6 on: November 15, 2017, 08:12:51 AM »
use an inverting unity gain buffer op-amp to flip the polarity of an unbalanced signal.

I already have a circuit for that..  know how to do that.

80hinhiding

Re: Phase Inversion Switch Circuit
« Reply #7 on: November 15, 2017, 08:14:24 AM »
That circuit for mono has essentially five components - 1 x Opamp and 4 x Resistor. How low a component count do you want ?

Yes I know.  However,  the opamp has many components inside it.

Recently PRR drew up a bare bones circuit for a differential line receiver.   When you feed an unbalanced signal to that, if polarity is flipped when going to the negative input I could probably use a 3PDT switch to flip balanced line input and change direction for the unbalanced input simultaneously.

Unless of course that circuit doesn't flip and/or the unbalanced signal has to go to both inputs.

Adam

scott2000

Re: Phase Inversion Switch Circuit
« Reply #8 on: November 15, 2017, 08:24:05 AM »
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!

80hinhiding

Re: Phase Inversion Switch Circuit
« Reply #9 on: November 15, 2017, 08:32:39 AM »
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!

Haha, my journey into tubes has started but I'm already very deep into this mixer using transistors, and have plenty stock left.  Getting nice results too.  I recently tried the passive EQ/tone controls that I posted a schematic to a while ago and was surprised by them.  Such a simple looking circuit on paper an in component count but effective.

If I had the luxury of input transformers I'd go that route.

Adam


joaquins

Re: Phase Inversion Switch Circuit
« Reply #10 on: November 15, 2017, 10:24:27 AM »
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
If I don't know how it works, I prefer don't turn it on.

Newmarket

Re: Phase Inversion Switch Circuit
« Reply #11 on: November 15, 2017, 12:54:46 PM »

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 ?