BSIAB2 help, please

[GonzoFonts]

I’ve been trying for the last three days to get this (damn) thing to work with no luck.     

For the record, I’ve built this on a breadboard and the schematic is below:



Here is where I’m at...

I can feed an input signal to the C1/R1/R2 junction and tap off the sound at the C6/Q3-gate and send that to my amp.

The sound at this point is very good, although it is a little high-endy. Either way, I know this works. By the way, there is already lots of gain with just the first gain stage.

I can feed an input signal to + side of C9 and send the output of R21 (Volume Pot) to my amp. This also works so I know my tone circuit works (although I do wish there was more range on the tone).

I can feed an input signal to the C1/R1/R2 junction and send that to the + side of C9 and send that to my amp. This also works so I know the first gain state and my tone circuit works. The addition of the tone circuit tames some of the high-endy sound I mention above, but the bottom line is that I know that this all works.

I’m having MAJOR problems adding the second gain stage which consists of Q3/Q4/Q5.

Adding this into my circuit just creates all kinds of feedback/oscillations/weird-noises.

I’m using 2N5457 in the second gain stage instead of J201s because:

   1) based on some of the threads on this board, this produces a better sound, and
   2) not to mention I don’t have any J201s on hand because I can’t find them anywhere in town, but I do have 2N5458s and NTE458s

I decided to re-build the second gain stage on a separate breadboard. What I noticed is that I cannot get a stable voltage measurement. For example, I will put my probe tip on the Q3-souce and the voltage will start at around 1.3V and then increase to around 2.2V or so . I can’t explain this at all  . I tried different transistors thinking that the ones I was using had been accidentally fried, but I get the same results (I also went back to the main breadboard and noticed the same â€" multiple builds, same results so I know I’m not going crazy â€" although at this point I feel like I am going crazy  )

Lastly, I can feed the Q3-gate with an input signal (but first, I go through a 0.47uF cap) and tap off the sound at the C12/R14/Q5-gate and send that to my amp. I get is what I mentioned before (i.e. feedback/oscillations/weird-noises).

Bottom line is that my second gain stage is all screwed up.

Any hints/tips would be appreciated.

Thanks in advance.

GF

PS: edited to add schematic to post