Big Muff Pi Circuit Analysis
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- čas přidán 22. 08. 2024
- In this video series I will be breaking down the circuit of the Electro Harmonix Big Muff Pi.
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Great video! Just a quick clarification. The AC and DC do in fact mix according to something called superposition. All that means is that the AC waveform is shifted up or down by the DC voltage. So if you had 1V AC mixed with 5V DC, the resulting signal would still look like AC waveform, but the midpoint would now be 5V with the peaks at 4V and 6V (whereas the 1V AC had a midpoint of 0V with peaks at -1V and +1V).
Ive just finished building a Big Muff Pi pedal, but i was only copying a schematic. I didnt actually understand the circuit.
This video is excellent. And really helped me understand what was actually happening inside the pedal.
Thanks so much.
One thing im really curious about is why the capacitor immediately after the input is orientated the way it is. My instinct tells me that the + leg should be on the input side, but its opposite.
Thanks for the excellent video. Really good stuff.
I've been looking for a channel like this. Easy breakdown of what's going on in effects pedals that even I can understand haha. Hope your channel gets huge man, excellent stuff.
This Video is phantastic! Please more of those circuit breakdown where every part is explained! I’ve learned so much!
This video is absolutely awesome! I've been so much time looking for someone to explain how a circuit ACTUALLY works!!! Thanks a lot for sharing!!!
Right??? Most vids are like “this is a capacitor! Moving on...”
But this channel explains what everything does and why it does it. I love it
26:36 Its a Bottom 😃
On a more serious note this is a very helpful video that can help a bunch of people see what's in front of them with clearer vision. Gold Star
That is one of the best explanations of a coupling capacitor I have heard! 👏
This is a great video! Helped me a lot in the process, currently in said process, of making my own overdrive pedal ... basically, it's gonna be a BM with the tonestage disenablable and a cleanblend - and downstream of mixing stage, another very very very slightly overdriving gain stage is gonna be introduced.
Until now, I'm playing with my prototypish device I wouldn't take onto any stage ... but I love adjusting, changing, trying out stuff, so this is fine with me. Once I got it all done, finished, tuned ... I'll have something that will make me a lot more satisfied than buying a buffered blender and another BM and some kind of cleanboost..
so, how did the build go ?
I feel like an echoplex set on a 1 year delay. 🙂 Just wanted to echo what everyone else is saying. I’ve been slowly studying electronics the last few years and have drilled into my head what caps, resistors, inductors, etc do but haven’t found many channels that go over circuits and how the signal flows, where is the dc going to, why the components used are there and this is perfect for me. Thank you so much for taking the time to make this video and share your knowledge. I also like how you start with the big picture (pointing out the 4 transistors and how this is more than most fuzz boxes have), then get into the nitty gritty of it all. I will definitely be looking at other videos you have made about circuit analysis. All the best to you and take care.
Excellent job. Way to explain it. Love the format for the video. Looking to build one soon.
If you still do these, I think a green ringer would be an interesting circuit to look at
This is an amazing resource that has help me to understand guitar what pedal schematics are doing, Many Thanks.
Awesome analysis. One more would be at 13:50. The current does not travel through the base into collector. The current from the base travels down into the emitter. The collector acts as a voltage controlled current source that reflected the base voltage so the current technical flows in from R13 which creates the inverted amplified signal before going into the next stage :) finally can put my EE degree into good use lol
Thank you very much man.This was really really useful!Cheers!
I am guessing at 14:12 that negative feedback comes from the fact that fraction of signal that is returned is 180 degree phased out compared to original, in that sens it is « negative »
I discover your channel and I must say respect !! Keep enjoying music and electronics
I love this kind of thing even more than I love watching Louis Rossmann desolder surface mount stuff. 🙂
Ehi this one I think is really important, I don't know if someone else pointed it out already...
Around 9:00 you talk about high pass filters, but if you put a resistor in series with a capacitor you ain't getting any filter at all, the two elements forming a high pass are the capacitor and the resistor put in parallel to the source signal (aka signal -> capacitor -> a wire which has a resistance connecting it to ground, and then from that wire you can go on.
"Reversewise" if you exchange capacitor and resistor you get a low pass (typical passive guitar tone). Both of them start relevant cutting at a cut-off frequency easily calculable by
f = 1/(2*pi*R*C).
Sorry for being so "pointy" but this could be very misleading for someone who hasn't studied the subject and could lead to non-working projects just because one builds all his filters (be it decoupling or something else) in the wrong way.
I tell from past experience😅
EDIT:
Also increasing values of R and C is ok, but there is another value, which unfortunately is basically the exact opposite of the cutoff frequency (aside from the 2*pi factor), and it is the time that it takes for the circuit to actually "cut-off" any signal above or below the cut-off frequency (wether you're using a low or high pass): it's called sometimes the "characteristic time" of the filter and is TAU = R*C. So, for example, let's say you need a basic decoupling high-pass: once you've rechead a cut-off frequency of 10Hz, there is no point in trying to get it lower even if you have tons of capacitor larger than the one you are using. If, for example, you thought it was useful to lower it by a factor of 10, and have 1Hz, you would have the side-effect of charateristic time increased by 10 too. It is usually in the order of the ms if not 100s of microseconds if I recall correctly, so it's a time far below the typical human reaction time, but I still think that it is better to keep it low, since lowering the cut-off frequency below a certain point is really unhearable. Try to run a network test on your filter if you have the instruments and you can see that once you are a few Herz below the minimum your instrument can play, there is really no attenuation at all affecting the signal.
I had some similar problem when I was designing a power stage for a circuit, where high value capacitors are sometimes needed
I believe that the input resistor R2 is there to diminish any radio noise. These are called grid stopper resistors in tube amps and are a common trick to prevent radio signals entering the amp.
it could also be used with the capacitor to set the cut-off frequency, as the resistance it's coupled to impacts the capacitor
Awesome Video!
Hmm... This one works great
18:12 cutting the highs and then getting them back through distortion and harmonic distortion is a pretty important part of Eric Clapton’s “woman tone” when he was in Cream, so that detail is pretty cool to me
TY. I subscribed!
That's a great demonstration of the circuit. I normally run my sustain very low, nearly off. What would I have to do to modify the circuit so I can use the full sweep of the sustain pot for greater control but still have my max at a low level?
this is so very helpful thanks alot!!
The nature of the RC filter on coupling caps. The final Volume control with a humbucker is 500k and having more resistance helps the same way a larger cap does. Raising all those resistance values might do as much of a significant tone change.
Noting the c10 is a bipolar and that in other schematics there's clipping diodes. Asymmetric and Symmetrical. I'm wondering the effects of using a polar cap for asymmetric treble bleed.. Especially on same side as asymmetric clipping diodes. So yeah 3 way switch.
But c6 there's polar series with symmetrical diodes.. When the next stage does it the signal is all opposites so one stage clips one way and cleans the next the reverse sides.
Regarding the negative feedback in the first transistor. You mention it cuts treble. You say increasing the capacitor value increases treble but I thought it was the opposite. A bigger capacitor would take off more treble I would have thought? If you can clear this up Bcs I am a bit confused by the negative feedback explanation sorry.
if you put both an inductor and a capacitor in the negative feedback of a transistor could you generate a mid cut via the negative feedback?
I had a NY version that beyond 12 at vol would make the amp silent and trip tube overheating warning. What could be the cause? Some coupling cap maybe that's gone bad? No shocks but a sensation of electricity.
thank you for your very helpful video. but what's the effect of 100nF caps? aren't they jut let high frequencies pass to the next level and remove low frequencies??
I have a big muff (that sounds odd!) that doesn't seem to power on. All I get when I press the footswitch is guitar-thru/guitar-block. The indicator light ( Given the vintage, I'm not sure if this is an LED or incandescent) doesn't come on at all. But after reviewing like 6 different schematics- none seem to show this indicator lamp. Can you tell me where in the circuit it is? I thought this was a good place to start tracing back to 9V to see whats-what!