Drive Pedal - Impedance issue?

[Barracuda]

So a quick introduction on what I'm working on, you'll see some similarities in the design to a rangemaster. Although this isn't built to be a boost pedal at the start of a chain, this is to offer a drive at the end of my pedal chain, as an alternative to an amp overdrive. I felt I could customize a lot more how my signal is being driven this way and just have a nice touch of distortion over everything to add colour, like a cranked valve amp, but with a couple adjustments to frequency response.

So what I have is sort of a slightly %^&*ed wah/bandpass fuzzy driven overdrive, I suppose. Here's the simply drawn schematic -



This works great when my guitar goes straight into it. However since this is going at the end of my pedal chain, I thought I'd test it with another effects pedal that I use - "Mooer Elec Lady" flanger. Like I said the drive is last in the chain so the signal goes to the flanger and THEN the drive. So when I turn the flanger on, I get a very nasty high end distortion ruining the tone of the drive completely. If you notice the drive design it has a 10nf cap grounded to make a low pass filter before anything else can be affected, so I'm a bit confused. I thought it may be an impedance issue, so I added a buffer, the TS9 input buffer to be exact..





The issue I had with this, is after the buffer, I add in the 10nf cap to ground and it really doesn't change the frequency response much at all, even after trying a 10uf cap to ground just to test it wasn't my breadboard, it just reduces the volume more than anything really, not much change in the frequencies. I'm looking for a way to solve/understand whats happening.

I tried to add the drive circuit in anyway, I needed to add a resistor in the signal chain of about 20k to feed the correct amount of signal into the drive transistor, and it does help some what, but I can no longer make a low pass/high pass filter like I did in the original design, or at least, don't know how to rectify the signal to be able to do so.

I'm somewhat uneducated on the actual theory of electronics so I thought I'd ask to see what the issue might be. I can upload some sound samples if necessary.

I'm using BC109 transistors by the way!

Thanks for your time!

[anotherjim]

That C1 is like an enforced guitar tone knob roll-off. There is meant to be a passive guitar plugged into it. It won't work at all as expected with an active pedal there instead. It will roll-off some highs, but they will be supersonic, so no surprise you didn't hear the expected effect.

There needs to be some series resistance before the cap. Put, say, a 6.8k resistor between the 10n and jack input tip.
To be a filter, it will be a low-pass RC type. The 10n is the C, you need the R! With a guitar plugged in, the impedance of the pickups is the R.
I could complicate things by saying the pickups are also L (inductance), making it an RLC filter, which is somewhat different behaviour compared to a simple RC, but hopefully it will be ok with just the added R.