Diode Lift in GGG's ITS8

[mrb1946]

The ITS8 was my first pedal and I just completed the original layout for it. Now I want to try out the "Expensive Boutique" mod, but I'm not sure how to do the diode lift, or what exactly that means. This was my first build and I did it pretty confidently after learning a lot of information through the internet the last couple of weeks. The exact instructions say, "disconnect the diode clippers from the feedback loop of the first stage of the circuit." Then it talks about using an SPDT switch as a diode selector switch. I am very lost at this point. Any help is appreciated.

[duck_arse]

hello mrb.

if you post or link to the circuit diagram, someon is sure to be able to point to and explain exactly what it is you need to do.

[mrb1946]

Great! Here's the original layout:
http://www.generalguitargadgets.com/pdf/ggg_its8_lo.pdf?phpMyAdmin=78482479fd7e7fc3768044a841b3e85a

This is the modifications PDF (I'm doing the expensive boutique mod):
http://www.generalguitargadgets.com/pdf/ggg_its8_mods.pdf?phpMyAdmin=78482479fd7e7fc3768044a841b3e85a

And here's the schematic, if that's helpful:
http://www.generalguitargadgets.com/pdf/ggg_its8_sc.pdf?phpMyAdmin=78482479fd7e7fc3768044a841b3e85a

[vigilante397]

I'm not remarkably familiar with the term either, but if I understand correctly they're talking about removing the diodes from the PCB and putting them on an ON-OFF-ON switch so you have the option to run the pedal without the clipping diodes for a "clean boost" type effect.

[mrb1946]

I'm not remarkably familiar with the term either, but if I understand correctly they're talking about removing the diodes from the PCB and putting them on an ON-OFF-ON switch so you have the option to run the pedal without the clipping diodes for a "clean boost" type effect.

How would I go about doing that? Would I have to get another circuit board?

[Buzz]

Hi.

Did you put in the switch which lets you choose between 1N4148 and LED clipper diodes?

Instead of the on/on switch to choose between diode types, use an on/off/on switch.

In the centre position (off) you should now have no clippers in the circuit and get clean boost.

I think that is what it means.

[pappasmurfsharem]

Hi.

Did you put in the switch which lets you choose between 1N4148 and LED clipper diodes?

Instead of the on/on switch to choose between diode types, use an on/off/on switch.

In the centre position (off) you should now have no clippers in the circuit and get clean boost.

I think that is what it means.

Or use LEDs in the middle and have 3 forms of clipping.

[mrb1946]

Hi.

Did you put in the switch which lets you choose between 1N4148 and LED clipper diodes?

Instead of the on/on switch to choose between diode types, use an on/off/on switch.

In the centre position (off) you should now have no clippers in the circuit and get clean boost.

I think that is what it means.

I did put in the switch. And it came with a off/on/off switch. And the middle position with the stock layout is not just a clean boost. It uses a clipper (can't remember which it uses in the middle position).

[Buzz]

The middle position ( off ) has lifted both sets of available clipping diodes from the signal path.

If you turn up the level knob you are now putting more signal through the op-amp than it can handle. So the op amp will clip. Maybe not in a very pretty way.

So this mod will only make a useful clean boost for a fraction of the available volume.

Some pedal mods are wow, others can be pretty so-so.

Don't forget this circuit was not designed to be a clean boost.

There are some great clean boosts out there with minimal parts count.

If you need a clean boost maybe it's time to start planning your next project.

Look up AMZ mosfet booster, LPB2, or even a jfet booster like the stratoblaster.

This is how the snowball starts rolling in this hobby... welcome to your new addiction!

[mrb1946]

The middle position ( off ) has lifted both sets of available clipping diodes from the signal path.

If you turn up the level knob you are now putting more signal through the op-amp than it can handle. So the op amp will clip. Maybe not in a very pretty way.

So this mod will only make a useful clean boost for a fraction of the available volume.

Some pedal mods are wow, others can be pretty so-so.

Don't forget this circuit was not designed to be a clean boost.

There are some great clean boosts out there with minimal parts count.

If you need a clean boost maybe it's time to start planning your next project.

Look up AMZ mosfet booster, LPB2, or even a jfet booster like the stratoblaster.

This is how the snowball starts rolling in this hobby... welcome to your new addiction!

Thanks! I already am quite addicted! I'm more interested in hearing the expensive boutique mod than hearing the clean boost, honestly. But I'm just trying to follow the directions for what it says, cause that's the kind of guy I am. Thanks for the post.

[duck_arse]

good luck following those directions. the D3//D4 leds don't seem to be included on the circuit diagram, except it shows D4 as the offboard status led. what have you fitted to your board, D1, D2a and b and the D3 and D4 leds? it seems to me that if you wire your on-off-on switch as shown, with the 5 diodes fitted, you have assymetric clipping, 2 leds clipping for more headroom, and no, or lifted, diodes, and only opamp clipping. then you just need to change the marked component values, and you will be hearing expensive boutiques in no time.