Muroidea - Triad Distortion - Rattler - ProCo Rat component usage

[harmaes]

There have been multiple discussions on the forum about the PackRat, Fat Rat and (Jam Pedals) Rattler.
I've build a legacy AION Helios pcb in the past but want to try out some other things so I ordered a Muroidea PCB. (The Triad Distortion wasn't in stock in the EU here)

I noticed that Jam Pedals uses a combination of carbon and metal film resistors in their Rattlers and in the leather version they use only carbon.
They don't seem to do this consistent because pics of the normal Rattler (red PCB) use carbon and metal film in different places.
So when using carbon resistors should I use these only in the audio path and metal film otherwise? The Limited Rattler (the expensive one) uses only carbon?

I modified the Helios based pedal yesterday and changed the 2x 1n4148 to include a 5mm Red led added to one side. This sounds quite cool IMO so I will incorporate that in the new build. Remarkable that the Limited Rattler uses only 2x 1n4148 and not a 5mm red Led on one side?

In the Pack Rat build report (https://forum.pedalpcb.com/threads/pack-rat-stock-turbo-“you-dirty”-rat-clipping-options.6202/) an interesting clipping option is added to the Triad Distortion PCB. I will add an on-off-on switch outside of the Muroidea PCB to select between 1n4148 with asym red led (5mm), 2x red leds and possibly 2x germanium to have more colors.
Which options do you prefer and suggest to try out?

 

[benny_profane]

Carbon comp resistors are used for aesthetics beyond anything else. If you like the look of it, go for it; otherwise, it will make little to no difference.

When setting up a three-way clipping switch with an ON-OFF-ON DPDT, put the clipping arrangement with the highest Vf so that it's always in circuit and the others so that they are selected with the switch. Per your idea, that means that the 5mm LEDs will always be in the circuit and will be active with the switch is in the OFF position. The other clipping modes will be active when the switch is in the corresponding ON position.

It sounds like you like asymmetrical clipping. A 2x1 arrangement of silicon diodes is a common clipping arrangement. You can use all the same type (e.g., 1n4148) or mix different part numbers (e.g., 1n4001 and 1n4148). Note that you won't be able to have 1n4148/1n4148+5mm LED with 2x 5mm LED with the ON-OFF-ON clipping switch. The 1n4148+5mm has a higher Vf than the single 5mm LED, and the single 5mm LED has a higher Vf than the single 1n4148. One clipping arrangement will have to have a higher Vf for both the positive and negative waves since it will always be in-circuit.

 

[harmaes]

Good to know about the carbon comp resistors.
To make things easier I will use an on-on switch to select between 2 options.
My question remains which clipping options are the most popular from experience?

 

[benny_profane]

Any of the stock clipping options are popular:

• You Dirty Rat: symmetrical germanium
• Turbo: Symmetrical LEDs
• Stock: Symmetrical silicon

Personally, I really like 2x1 asymmetrical silicon. I typically do 2x1 1n914 or 1n4148. Definitely experiment and see what you prefer. Breadboard the circuit so you can try out any number of clipping arrangements.

 

[Barry]

They put those Carbon comps in there so the cork sniffers who pay ridiculous money for them think their getting something special

 

[harmaes]

I’ve decided to use a 6-way rotary switch to select between clipping options like: asymm 1n4148+ 1n4148/5mm red, asymm 1n4148, symm 3mm red leds, symm 1n4148, a
symm mosfet+bat41 (like the Zendrive), symm mosfet+germanium

​

 

[jimilee]

I made a pcb with 8 different options. 6 is a little more sensible.

 

[Barry]

I’ve decided to use a 6-way rotary switch to select between clipping options like: asymm 1n4148+ 1n4148/5mm red, asymm 1n4148, symm 3mm red leds, symm 1n4148, a
symm mosfet+bat41 (like the Zendrive), symm mosfet+germanium

​

1n4148 + 1n4001 is a nice combo

 

[harmaes]

I made a pcb with 8 different options. 6 is a little more sensible.

Will check it out!

 

[jimilee]

Will check it out!

Here's the schematic, probably make it easier to see what's going on. I think 8 was too many, for sure. 6 is about right.

 

[harmaes]

Here's the schematic, probably make it easier to see what's going on. I think 8 was too many, for sure. 6 is about right.

The schematic seems to be printed mirrored?

 

[jimilee]

Dammit!!! Here is one not mirrored

 

[harmaes]

Dammit!!! Here is one not mirrored

Thanks for sharing!

The issue I have with some combinations is the large volume drop. The symmetrical germaniums have to be compensated too much IMO. So why did you choose the asymm 3mm red led with the 2n7000? I have symmetrical germaniums with mosfet and bat41 with mosfet, will probably configure one as symm and the other as asymm.
I will test some of your other combinations when I’m building the pedal!

 

[jimilee]

Thanks for sharing!

The issue I have with some combinations is the large volume drop. The symmetrical germaniums have to be compensated too much IMO. So why did you choose the asymm 3mm red led with the 2n7000? I have symmetrical germaniums with mosfet and bat41 with mosfet, will probably configure one as symm and the other as asymm.
I will test some of your other combinations when I’m building the pedal!

This was really an experiment in I wonder what would happen if. I couldn’t find any PCBs so I decided to make my own.

The Roadkill / Brat Rat has soft clipping, so I threw that in there, too.

Honestly, I use 3mm in everything, it was just habit, and I like the eagle footprint better. A 5mm will work just as well.It sounds great, though.

The germanium’s I used were D9Ks I believe. The volume drop isn’t as bad as the 1n34a’s.

Red LEDs will always be screaming loud.

 

[harmaes]

I’ve build the Muroidea and compared to the AION Helios legacy I build a few years ago the Muriodea becomes or sounds more nasal when increasing gain. The Helios has the Ruetz mod but in minimum it shouldn’t work. Component wise the filter is similar and the voicings in the loop of the opamp are similar too.
So what influences the “nasal” frequencies most in the rat circuit and maybe because I build one without a Ruetz mod it might be something all rat pedals have somewhat?

 

[harmaes]

Running the gain at 3 oc and reducing the volume on the guitar results in a strong cocked wah sound. I checked all component values so that’s not it. What’s your experience with the Muroidea?

 

[harmaes]

Ok, the 2 caps around the 560R and 47R were broken somehow, I noticed a change in behavior when adding the Ruetz mod and after replacing the caps (2,2u and 4,7u) the issue resolved.