# Big Muff "47" Ram's Head



## almondcity (Apr 27, 2022)

Just looking at random variants to build

The schematic on kit rae seems weird in that the 2 clipping stages are not symmetric:





Doesn't it seem more likely that C6 is 47n and C13 is 470n rather than the values shown?  Anyone built one of these?


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## Coda (Apr 27, 2022)

That may be a typo. I believe its 470nf for both.


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## Feral Feline (Apr 27, 2022)

Yeah, nothing in life is absolutely perfect. On the KR site I've seen typos and even a few outright errors (corroborated by info & traces from other sites). 

Alas, some of the more egregious known-errors haven't ever been corrected. Always good to cross-check...











Still a good wealth of information on KR's Muff pages, and I'm grateful for it being there as a resource, use it all the time.


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## almondcity (Apr 27, 2022)

Yeah I've seen some other errors. I haven't found a way to check this since every single source on the internet references this one page haha


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## almondcity (Apr 27, 2022)

Going off the schematic for the Pharaoh from Aion, which is based off the 47 BM, I think it makes sense for input and output caps to be 470n and all the others to be 47n


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## Coda (Apr 27, 2022)

almondcity said:


> Going off the schematic for the Pharaoh from Aion, which is based off the 47 BM, I think it makes sense for input and output caps to be 470n and all the others to be 47n



I believe there is a variant of the Triangle that used 50n in that place, so 47n wouldnt be too far away. Of course, those two components would be identical. So I would socket those spots, and swap out between 470n and 47n…


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## Dan M (Apr 27, 2022)

almondcity said:


> Going off the schematic for the Pharaoh from Aion, which is based off the 47 BM, I think it makes sense for input and output caps to be 470n and all the others to be 47n


Be careful with the Pharaoh, I think the schematics at the Aion and kit rae sites are wrong.  There should be no 47n.  Only 470n and 470p.

Granted, I haven't traced one myself, I'm going off of this thread:




__





						Black Arts Toneworks - Pharaoh - Page 5
					

Hi everyone, Just ran across a new muff variant that's been getting some buzz on ilovefuzz. The sound samples come off pretty great and the price is reasonable, I feel. Read somewhere that the tone stack is a Baxandall work-alike. Anyone have any ideas




					www.freestompboxes.org
				




I built it that way, and it sounds right:




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						2x Muff:  Aion Osiris + Grind Customs Ultrastoner
					

This is an older build, complete with: 1.  Part selection that was too large and had to be jammed/bent into place 2.  Melted cap corners 3.  General janky soldering and assembly  But it is a beast!  The boards are Aion Osiris, so the Pharaoh side was straight forward.  The Ultrastoner needed...




					forum.pedalpcb.com


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## Coda (Apr 27, 2022)

You know, I’ve been planning to build a 47 soon. I’ll definitely socket and try both, just to compare. Maybe it is correct? Who knows?…


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## mdc (Apr 27, 2022)

Just curious why you think the values are incorrect? 470n is a pretty large value for a coupling cap in a muff, it would make sense to me that they'd want to tame the bass to some degree at some point in the circuit, and a smaller value coupling cap and blocking cap would be a way to do that pretty effectively.


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## Big Monk (Apr 27, 2022)

My recent rabbit hole has been reading the forward voltage ranges for vintage muffs on Kit Rae. 

Looking to get some 0.5-0.6 vDC diodes from Small Bear because I’m a psycho.


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## fig (Apr 27, 2022)

Coda said:


> You know, I’ve been planning to build a 47 soon. I’ll definitely socket and try both, just to compare. Maybe it is correct? Who knows?…


You mean a 470?


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## almondcity (Apr 27, 2022)

mdc said:


> Just curious why you think the values are incorrect? 470n is a pretty large value for a coupling cap in a muff, it would make sense to me that they'd want to tame the bass to some degree at some point in the circuit, and a smaller value coupling cap and blocking cap would be a way to do that pretty effectively.


I'm just curious.  My monkey brain wants symmetry


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## Coda (Apr 27, 2022)

fig said:


> You mean a 470?


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## Feral Feline (Apr 28, 2022)

Soilent Green is 470 420


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## ICTRock (Apr 28, 2022)

They've got perfectly good pictures of the pcbs over on the site, you can certainly verify this pretty easily by comparing this to other variations as the parts values changed but the PCB layout did not.


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## Coda (Apr 28, 2022)

If you read the write up on the Kit Rae site it mentions the “large .47uf coupling and filter caps…”, which leads me to believe further that the 47n was a typo.


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## ICTRock (Apr 28, 2022)

Certainly a possibility, the schematic has two Q4s.


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## Big Monk (Apr 28, 2022)

@Coda is our Muff diver supreme so everyone else sounds like Charlie Brown adults to me...


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## ICTRock (Apr 28, 2022)

Schematic holds up.
A good look at C6


			http://www.kitrae.net/music/Images_Secret_Music_Page/Ollys_47_V2_4.jpg
		

A good look at C13


			http://www.kitrae.net/music/GregSmith_Rams_Head.jpg


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## Coda (Apr 28, 2022)

ICTRock said:


> Schematic holds up.
> A good look at C6
> 
> 
> ...



Good eye. Looks like the schematic is (mostly) typo free. I would go with the schematic.


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## Coda (Apr 28, 2022)

Big Monk said:


> @Coda is our Muff diver supreme so everyone else sounds like Charlie Brown adults to me...



Good grief. Plenty know more than me….


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## Feral Feline (Apr 28, 2022)

ICTRock said:


> Schematic holds up.
> ...


So there ARE two Q4s

Well spotted!


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## ICTRock (Apr 28, 2022)

They need to own and fix the two Q4 labels but as far as parts values, the schematic is correct. Also a small part of me imagines some future idiot posting on a troubleshooting thread about the pedal not working because of the two Q4 issue.


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## almondcity (Apr 28, 2022)

Thanks for the sleuthing. I didn't realize the site had pictures like that. I'll be building one soon

In the spirit of the pedal I'd probably use 4.7n for the tone caps and tweak the resistors


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## ICTRock (Apr 28, 2022)

28K + 4n7 and your corner frequency will increase about 4 Hz.  Probably your best bet for a sub - he said before considering common resistor values. sub 3n9 and keep the 33K, corner increases 31Hz


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