Circuit explanation help
- Thread starter Toastman
- Start date
hamerfan
Well-known member
I am not in position to explain everything, but i found the circuit analysis of electrosmash useful to understand the basics.
www.electrosmash.com
I also saw some vids of Brian Wampler on this topic.
ElectroSmash - Big Muff Pi Analysis
Circuit, List of Materials / Parts List, Input Booster Stage, Shunt Feedback Common Emitter Stage, Input Booster Voltage Gain Calculation, Input Impedance Calculation, Input Booster Frequency Response, Clipping Stage, Sustain Circuit, Clipping Amplifier V
JohnnyCreepy
Well-known member
Im so sorry I did this:
Look up the fuzz face analysis on ElectroSmash site.
Look up the fuzz face analysis on ElectroSmash site.
Very helpful linkI am not in position to explain everything, but i found the circuit analysis of electrosmash useful to understand the basics.
I also saw some vids of Brian Wampler on this topic.ElectroSmash - Big Muff Pi Analysis
Circuit, List of Materials / Parts List, Input Booster Stage, Shunt Feedback Common Emitter Stage, Input Booster Voltage Gain Calculation, Input Impedance Calculation, Input Booster Frequency Response, Clipping Stage, Sustain Circuit, Clipping Amplifier V
Feral Feline
Well-known member
+1 for Electrosmash
Also Small Bear has some good info on the Fuzz Face topology:
READ "Technology of the Fuzz Face — By RG KEEN", you can find it here:
Q2 & Q3 are forming a Darlington Pair, effectively acting as a single transistor, so don't let that throw you when looking at all the Fuzz Face info out there...
en.wikipedia.org
Also Small Bear has some good info on the Fuzz Face topology:
READ "Technology of the Fuzz Face — By RG KEEN", you can find it here:
Q2 & Q3 are forming a Darlington Pair, effectively acting as a single transistor, so don't let that throw you when looking at all the Fuzz Face info out there...
Darlington transistor - Wikipedia
Chuck D. Bones
Circuit Wizard
It's nothing like a Fuzz Face or Big Muff. It's a rather unique circuit.
Q2 bootstraps Q1's collector via R4, except when GAIN is dimed. Boostrapping effectively raises the impedance of R4 which increases Q1's gain. Q3 loads Q2's emitter. At low to medium GAIN settings, Q3's input impedance is fairly high and the loading of Q2 is minimal. However, when GAIN approaches 10, Q3's input impedance drops significantly which loads Q2 and weakens the boostrapping effect. Max gain is around 55dB at 1KHz.
Q1 & Q2 run right at the edge of saturation. Q3's biasing results in asymmetric clipping for most signal levels and GAIN settings. We can improve the symmetry by reducing R6. If we want to add a BIAS knob, we could replace R6 with a 1K resistor and a 10K pot.
The TONE network is a bridged-T notch filter. It creates a broad scoop centered at 1.7KHz that affects mid and treble frequencies. Maximum notch depth is around 8dB.
Is that enough detail? I don't go part-by-part, but I do describe how it works.
Q2 bootstraps Q1's collector via R4, except when GAIN is dimed. Boostrapping effectively raises the impedance of R4 which increases Q1's gain. Q3 loads Q2's emitter. At low to medium GAIN settings, Q3's input impedance is fairly high and the loading of Q2 is minimal. However, when GAIN approaches 10, Q3's input impedance drops significantly which loads Q2 and weakens the boostrapping effect. Max gain is around 55dB at 1KHz.
Q1 & Q2 run right at the edge of saturation. Q3's biasing results in asymmetric clipping for most signal levels and GAIN settings. We can improve the symmetry by reducing R6. If we want to add a BIAS knob, we could replace R6 with a 1K resistor and a 10K pot.
The TONE network is a bridged-T notch filter. It creates a broad scoop centered at 1.7KHz that affects mid and treble frequencies. Maximum notch depth is around 8dB.
Is that enough detail? I don't go part-by-part, but I do describe how it works.
Feral Feline
Well-known member
Thanks for that, Chuck.
Did I at least peg the Darlington correctly?
Did I at least peg the Darlington correctly?
falco_femoralis
Well-known member
This needs to be moved to an after hours discussion...
Chuck D. Bones
Circuit Wizard
Pretty much. On both counts. 
