red llama oscillations

[shzmm]

hello
i am currently building the red llama clone from the schematic at the gauss markov site: http://gaussmarkov.net/index.php?page=layouts#redllama.  it is being built on perfboard though...
so the difficulty i am having is between different 4049 chips.  i have one at the moment that is HCF4049ube the others are CD4049ube.  anyways the HCF version is a strange beast.  the gain is increased considerably albeit not at all in a bad way-- the pedal sounds much rawer and wilder.  i tried increasing the the value of R2 to 220k to replicate the sound but it still doesn't quite get it, the CD versions just sound tame in comparison. 
the problem is that when the gain pot is turned around 3/4 of the way up with the HCF version the effect begins to oscillate at a steady tone.  the tone changes pitch as the pot is turned upwards-- as well when adjusting the volume pot on the guitar.  with enough decrease in level from the guitar the oscillation goes away.  interestingly, when there is no signal from the guitar the oscillation comes back. 
i have already read in anderton's EPFM book that increasing the value of C3(in the GM schematic) should help but i'm not getting any change there.  i also decreased the value of R2 but it didn't help much either. 
anyone have any suggestions to cure the oscillation ills?  i'm not sure of the differences between the types of 4049s maybe it's worth a look
thanks

[Lachlan C.]

Hi shzmm,

                 Some possible solutions to your oscillation problems are:     (1) Using shielded cable on the input and output jacks.
                                                                                                       (2) Using shielded cable on the volume and drive pots.
                                                                                                       (3) Making sure that the layout is well thought out and the grounds return to a single point.
                                                                                                                   
These tips are good practice on most pedals but are almost mandatory on high gain distortion builds. Also more problems may be sorted with feedback and noise issues once you have the circuit in a metal enclosure. Check out the posts on the Dr Boogey stompbox (High gain distortion circuit) as some of them elaborate and reiterate the above solutions/precautions

Cheers - Lach

[tcobretti]

I found this in the archives:

Hi.
I've built a tame one with a 10k input pot and 100k feedback resistors around each inverter.  It's quite mild.  For details, see my website.
cheers

That's Brett, who's a regular poster here, but I couldn't find his website.

You might be able to apply this idea to lessen the gain of the circuit enough so it won't oscillate.