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Old Yesterday, 05:11 PM   #44921
mmolteratx
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Quote:
Originally Posted by TNfootballfan62
From just kind of a circuit analysis perspective, I think those two typologies are equivalent. In terms of clipping, I'm not sure how changing the positions might change things if at all.

EDIT: I bet that cap in series with the diodes is a coupling cap to remove the DC bias. It probably doesn't matter if it's before or after.


Yea, it's only there to block DC since without it you'd be limited to a Vbc of a diode drop. You can use it to shape the clipping, but with the stock values, it's pretty much clipping everything. And order never matters for series components.

Quote:
Originally Posted by TNfootballfan62
It's been a long, long time since I've looked at a pedal schematic, but I'm interested in that gain stage. Looks like the big muffs are all kind of the same: common emitter stages with negative feedback loops. Interesting! The negative feedback resistor probably controls DC gain, while the diodes obviously provide some signal clipping. With just a capacitor in the loop, that would end up looking like a miller capacitance at the input--I wonder if that's the point?


Yea, the cap is there to cut high end for less fizz. That particular configuration is patented, though I can't remember the patent number off hand. It's really just your basic self biased stage with an extra resistor to ground at the base and emitter degeneration as far as DC is concerned, I don't know how that patent was granted. I guess the clipping might have been novel at the time.
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Old Yesterday, 06:04 PM   #44922
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Quote:
Originally Posted by TNfootballfan62
From just kind of a circuit analysis perspective, I think those two typologies are equivalent. In terms of clipping, I'm not sure how changing the positions might change things if at all.

EDIT: I bet that cap in series with the diodes is a coupling cap to remove the DC bias. It probably doesn't matter if it's before or after.


According to kitrae, that cap is there for the DC bias.
And frequency stuff (Excuse me, i just woke up).



I'm working on a muff layout with an option switch.
One position is standard configuration.
The other switch position, I'm looking at 1 of 3 possible options:
  1. Cap value switch
  2. Remove clipping from first clipping stage (ALA Colorsound Supa Tone Bender)
  3. Swap diodes

The first 2 are easy.
The 3rd, from a PCB design perspective is a little different
Still thinking about how I wanna do that. And the reason for swapping cap and diode order.
It would be brain dead easy using some jumpers, but I wanna avoid that.
A PCB shouldn't have jumpers. IMO.
At least with simple pedal circuits.

Thanks
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Old Yesterday, 06:05 PM   #44923
TNfootballfan62
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Quote:
Originally Posted by mmolteratx
Yea, it's only there to block DC since without it you'd be limited to a Vbc of a diode drop. You can use it to shape the clipping, but with the stock values, it's pretty much clipping everything. And order never matters for series components.



Yea, the cap is there to cut high end for less fizz. That particular configuration is patented, though I can't remember the patent number off hand. It's really just your basic self biased stage with an extra resistor to ground at the base and emitter degeneration as far as DC is concerned, I don't know how that patent was granted. I guess the clipping might have been novel at the time.



I've been grading so much the last few days I can practically see the small signal analysis of that circuit in my head.

I suppose the magic with building pedals is going from "Yep, that cap cuts high end" to "Yep, that cap cuts high end for less fizz."

EDIT: ^Looks like I nailed most of the analysis off hand. Maybe all this education is actually good for something.
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Old Yesterday, 06:13 PM   #44924
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Originally Posted by Dave_Mc
can you use words like "djent", "brootz" and "cookie monster"?

If you can't, I'd (black)lodge a formal complaint.
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Old Yesterday, 06:29 PM   #44925
mmolteratx
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Quote:
Originally Posted by TNfootballfan62
I've been grading so much the last few days I can practically see the small signal analysis of that circuit in my head.

I suppose the magic with building pedals is going from "Yep, that cap cuts high end" to "Yep, that cap cuts high end for less fizz."

EDIT: ^Looks like I nailed most of the analysis off hand. Maybe all this education is actually good for something.


Pretty much. The magic is in the frequency shaping pre and post clipping. I've been saying that for freaking forever at this point. It's a big reason I think the Fortin Natas and all of its derivatives are such a great design.
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Old Yesterday, 06:57 PM   #44926
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^ Design one.
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Old Yesterday, 07:12 PM   #44927
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This just popped up on my radar:

https://reverb.com/item/457053-2011...tom-made-guitar

I have a semihollow version of this model, with a plain cherrywood top. This is a STEAL- Jon's flag guitars go for $2500+ new these days, depending on complexity. The craftsmanship is excellent. That is NOT a paint job, that is all woodwork, carefully cut and pieced together. The frets are blind set, which is to say that their edges are contained within the fretboard and neck, which means no binding is needed to protect the hand from sharp bits of metal.
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Old Yesterday, 07:40 PM   #44928
TNfootballfan62
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Quote:
Originally Posted by mmolteratx
Pretty much. The magic is in the frequency shaping pre and post clipping. I've been saying that for freaking forever at this point. It's a big reason I think the Fortin Natas and all of its derivatives are such a great design.


Yeah, I'll occasionally think to myself, "You know, I'm a good circuit designer. I should just design some pedals. I can do it."

Then I remember I have no idea what actually goes into making a pedal sound "good." There's such a disconnect between conventional electronics wisdom and "good" electronics design and making things that sound good.
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Old Yesterday, 07:48 PM   #44929
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Quote:
Originally Posted by TNfootballfan62
Yeah, I'll occasionally think to myself, "You know, I'm a good circuit designer. I should just design some pedals. I can do it."

Then I remember I have no idea what actually goes into making a pedal sound "good." There's such a disconnect between conventional electronics wisdom and "good" electronics design and making things that sound good.


Just remember to cut your lows and highs before clipping and you're all good.

Oh, and balancing gain can be difficult. It usually doesn't sound all that great when you try to wrangle a bunch out of one stage versus cascading another stage or two.
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Old Yesterday, 07:54 PM   #44930
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Originally Posted by Dave_Mc
is the t75 broken in? my (unbroken in ) one was fizz city (don't get me wrong, i like some fizz for certain things). unless it loses some of that when broken in.
Very much so, the T75 came out of my old JCM900 combo. It's the greenback that sounded fizzy. It's not really broken in properly but I don't think that's the problem. It is sort of broken in, it just doesn't suit what I am playing. I didn't like the greenback 4x12 with the RM100 either.



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Old Yesterday, 08:25 PM   #44931
mmolteratx
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Oh, and Kyle, I found out what an ER band pass filter is. ER stands for equal ripple. It's just a stupid name for a Chebyshev filter. This lab manual sucks ass. They refer to the Butterworth filter as MF for maximally flat, which was easy enough to figure out, but ER threw me for a loop.
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Old Yesterday, 09:37 PM   #44932
TNfootballfan62
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Quote:
Originally Posted by mmolteratx
Oh, and Kyle, I found out what an ER band pass filter is. ER stands for equal ripple. It's just a stupid name for a Chebyshev filter. This lab manual sucks ass. They refer to the Butterworth filter as MF for maximally flat, which was easy enough to figure out, but ER threw me for a loop.


I have literally never seen those filters called ER and MF.

I suppose those names are much more descriptive so long as you know what ER and MF stand for, but that would be really frustrating.

Quote:
Originally Posted by mmolteratx
Just remember to cut your lows and highs before clipping and you're all good.

Oh, and balancing gain can be difficult. It usually doesn't sound all that great when you try to wrangle a bunch out of one stage versus cascading another stage or two.


Yeah, pushing a stage too far in almost any application is normally not a great idea. Operating near the edge of what a device can do is asking for inconsistencies in the circuit, and in a multistage amp if one of them is too hot, you can run into noise problems or stability problems or whatever.

That's actually one thing that jumped out at me with the Muff. The topology looks like it uses several stages of controlled gain and clipping to produce a really massive fuzz instead of trying to swing a signal rail to rail with a single transistor circuit. I like it.
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