LTSpice not looking like the actual measurement

[Enron]

I have the hardware made for this chorus guitar pedal schematic:
http://www.geofex.com/PCB_layouts/Layouts/zombie.pdf

The pedal sounds perfect when I hook up my guitar through it, to my amp. During the making of this, I used LTSpice for each stage of the circuit. The first stage measured on the actual hardware looks very different than what LTSpice shows.

I have an image of the actual reading from the hardware. I set both my function gen and my LTSpice original signal to 1V p-p at 440Hz.

The LTSpice file signal references are:

Blue: Original signal out of V1
Green: Signal after the cap

The first photo is being measured after the cap in LTSpice (about 1Vpp in the +5.4V area), and the second photo is being measured after the cap on the actual hardware (about 1Vpp in the +1.5V area).

Is this a problem that most people have using spice programs? Or can someone spot out something that I might doing wrong.

Also for the Vb reference on the actual hard, I am measuring 5.3V. The output of the opamp appears to be the same on both LTSpice and the hardware.

EDIT: Just added LTSpice files, so if anyone wants to look at them.

[PA0PBZ]

Your scope input impedance is not infinite, so what you are doing while measuring is adding an extra (10M?) resistor from the + input of the op-amp to ground. My guess is when you do that in LT Spice it will show you the same.

[Enron]

Both setups are exactly the same. There is a 10M to ground on the + of the opamp on both LTSpice and circuit board.

[PA0PBZ]

Yes, but you are not poking a physical scope probe in your simulation do you? Please read my first reply again...

[Enron]

I added a 1M ohm from + opamp to GND. My Rigol has a input impedance of 1M. Now I am getting what the Rigol is in LTSPice.

Do I have to do this at every point now (add 1M to GND) that I want to measure to get what the actual hardware reads?

[PA0PBZ]

I added a 1M ohm from + opamp to GND. My Rigol has a input impedance of 1M. Now I am getting what the Rigol is in LTSPice.

You don't have x10 probes? They should give you a 10M input impedance.

Do I have to do this at every point now (add 1M to GND) that I want to measure to get what the actual hardware reads?

No, only on high impedance points. You can imagine that having 10M impedance in your circuit and then adding 1M to ground will do something to the result, normally you will not encounter this. If in doubt just temporary add a 1M/10M resistor and see what happens.

[Enron]

Thanks for all the help. My main problem was that I was using x1 on my probe.

I switched it to x10 on the probe and scope, added a 10M to the +opamp and the number match perfectly. Thanks you so much PA0PBZ for your observations. kudos

[PA0PBZ]

No problem, it's always good to see another mystery solved! 

[w2aew]

Thanks for all the help. My main problem was that I was using x1 on my probe.

I switched it to x10 on the probe and scope, added a 10M to the +opamp and the number match perfectly. Thanks you so much PA0PBZ for your observations. kudos

The thing you didn't take into account in the simulation was the capacitance associated with the 1x probe - probably on the order of 60-100pF (scope input capacitance and the coax capacitance).