Pre Amp Build. Basic Theory Questions

[SilverFox]

Here is the schematic for the amp in question with some scope shots and as built voltage readings.

[link] http://s7.postimg.org/xa5x1ao8b/Preamp_Clean_Post.png

The circuit is built up to C23 and R37.

I want to test this portion of the circuit before proceeding further and have a series of questions. Any assistance would be greatly appreciated.

This Pre is taken from the first stages of a Peavey Road Master that I've converted into a test chassis.

Questions: The first 3 scope shots are taken with the input grounded and show lots of static and noise .2ms and 10V / CM. I think it is just noise but it looks like some sort of oscillations?

When I injected the .2 volt CAL signal from the scope and put the V/div at 5 on the scope I got screen shot "D" The signal cleaned up very well?

If I vary R33, Pre drive the output ACV level rises from 0 to 86 VAC as measured at the output side of C23.

It appears the circuit is working but I'm not sure.

If someone could explain the biasing of the stages, I've read Merlins book and the other information here so I'm gaining a better understanding.

I've included the biasing values in the table in the schematic. Originally the supply resistor (R4) was 100K but the voltage was running 301 on the first stage so I tried changing it to 180K and that dropped the voltage but did it change the Headroom?

I also changed the input resistor from (2) 22K resistors to (1) 33K Do I have signal noise now entering the circuit?

I am considering adding a basic coupling RC network at this point at the output cap and either driving the power amp at about 2 V PP or feeding it into a mixer and then into the power amp. If I omit the tone stack from the circuit, what sort of values would I use to simply couple the existing signal to a mixer input or the power amp?

Thanks for any information you may be able to provide. I ultimately want to interface the pre with the power amp portion of the Road Master. I rebuilt it to reduce the power level and used different Iron. this portion does work just fine so I only have to build the Clean channel and I'm done with the first part of build.

The objective is to build a basic clean channel that I can drive with an effects box, amp emulator and perhaps add an overdrive circuit to, in the future. Something like the Dumble OD circuit.

Silverfox.