pop free switching help on multiamp pedal switcher

[njkmonty]

The following is one of these multiamp hum free type multi amp schematics.
ive had it working and currently have it breadboarded
i want to be able to now have 4 separate switches  added to it, but i obviously do not want any popping
the 4 switches are to turn on and off  the following:
Direct Out
3 x Isolated amp jacks.
Ie so i can have the different combinations of amps running as appose to have all on?
do i simply just ground the isolated jacks tip to its sleeve?
do i disconnect the connection marked with a yellow highlighter (before or after the 10K resistor  going into the opamp?)
or both or something else?

[samhay]

Have you drawn the inputs of the 3 op-amps driving your isolated inputs inverted?
If not, what are the 10k resistors in the feedback loop doing?
If so, short these resistors and you will get no output.

[amptramp]

Resistors in the feedback loop as shown here are usually used to equalize the contribution to offset voltage caused by bias current.  If you are running FET input amplifiers with bias currents in the nanoamps, they can be eliminated.  If you are running bipolar amps, the input bias current is sufficiently high that the drop across the 10K resistor will result in a noticeable offset voltage.  By matching the resistance seen at both + and - inputs, the effect from bias current is cancelled and only the effect of input offset current remains.  There are limits to this - enough change in bias voltage and your headroom limit could be approached.

[njkmonty]

Ive been currently using 2 schematics to work from which i printed out about 4 years ago




i just went online to have another look and notice R.G. Keen has updated it!

http://www.geofex.com/FX_images/TransformerSplitter.pdf



I gather applying the latest schematic will allow me to achieve the results i want by connecting the main primary wire to ground from the selected isolated outlet?

[PRR]

[njkmonty]

just a quick update  ive managed to get it working  by shorting the output jacks like you said, but i havent updated the cap and resistor adjustments recommended.
One thing I did was  i inserted a madbeen mxr flanger clone directly from guitar and before the switcher, and I get very audible lfo disturbances through the amps,
ie  the switcher works perfectly playing  through 3 seperate amps, no pops etc, but as soon as i put an effect infront of it, causes probs,
I even used a battery for the flanger but no change.
any suggestions ideas would be great