Bias is set via the 25K trimmer at collector of Q1 and resting voltage at collector Q2 would then be set at 4,5V. For the Sparkling Faces that I made for this thread I have set bias with AC signal sine wave with Saturation control fully counterclockwise to allow near linear operation when signal is below clipping threshhold and so onset of distortion is gradual and gradually increasing. This setting allows for also a type of distorted sound that I have heard on many recordings with Hendrix and wondered how he got it as it somewhat sounds like a fuzz but also somewhat like distortion....
To my ear these transistors lend themselves well to this type of sounds
As I mentioned in another post I also made a a while ago a FF with BC108C transistors but with that I felt more to go with nonlinear from start as the sound and playability was more fun that way with those transistors.
Actually they do a whole lot and I was going to make a few Fuzz109’s but the bag of BC109C’s ( very low noise, high gain, low voltage audio transistor for preamps et.c) I had had disappeared so as I anyway wanted to complete what I had started I checked out some other transistors I had in drawers and thought of trying 2N1711 ( medium power,medium gain switching- and driver-transistor) and those have about as much as common that they both are NPN and in metal can…
The circuit had to be revised to let the 2N1711 bias correctly for what I wanted and also while you can do certain noise reduction things with transistors those vary from type to type and as an example one that makes 2N1711 drop a little noise makes the F109 oscillate I am saying when you use a part there can certain things you can do.
Sound wise and on musical level things could be broken down like this
The Square Wave is a resurrection with some modifications to a fuzz I used a whole lot live and in studios in the late 1980’s- it can sound almost behaved with volume control on guitar turned down a little and then sound like a disaster when volume control is on full- I always enjoyed having that on dial
The Fuzz 109 came about as I was building fuzzes and listening to Hendrix for hours on end and as I was making the Sparkle Faces it struck me that while close there would be something else I’d hear in the Hendrix fuzz sounds and there’s these sounds where he gets a fuzz sound that more sounds like a distorting amplifier in that more organic for lack of better word than distortion boxes and this would be a sound I have wanted to have since I first heard it. So I set about making the Fuzz 109 using silicon transistors as it struck me that the recordings I was listening to would have been made with the latest most likely of fuzz faces.
Now there are some high order distortions that occour in the BC109C that is not present in say the 2N1308’s and I recalled some techniques to reduce that and in the process total noise level and I feel the resulting sound and behavior makes something useful to me and a sound I could use any day.
This is about sounds that woke my desire to play guitar and that have lingered through the years- I could think of sounds of disaster but this is not it this time.
The Sparkle Face I wanted to make with more modern germanium transistors and for a close to linear design that would eventually overload and in that making a sound from seemingly clean to heavy fuzz and doing that gradually- there are of course some interesting ’odd' things that would then be dialed out, such that would be viewed as the sound of fuzz and that make sound gate and spit and duck- while I in later years enjoy such things too I could think of circuits to more fully explore the noises.