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Mammal : Power supply

Lag

New member
Hello on the PCB of Mammal (Animal), there not the resistor 56R as original schematic and there is a diode 1N5817 instead.
Can you explain this différence.
Thanks you in advance
 

HamishR

Well-known member
There are various ways to reduce the noise you might get from a power supply. The idea is to isolate the circuit from noise and interference with either a resistor (low value so as not to drop too much voltage) or with a diode to prevent AC ripple or protect from the wrong polarity.

It seems to be standard in current Rockett FX to use a 10ohm resistor and a 1N4001 diode.

FWIW I didn't understand the importance of the diode on the voltage input until I took a pedal I had built (without a diode or resistor) to show a friend. When we plugged the pedal in with his cheap power supply the pedal howled with a whining noise and was unusable. So the next time I took it to show him I had soldered in a 1N5817 between the socket and the board and everything worked perfectly. I never have these problems at home because I use a decent power supply.

Using a few pedals together you may experience noise from pedals sharing a power supply. These diodes and resistors can help reduce this noise and interference.
 

Chuck D. Bones

Well-known member
The importance of a good power supply cannot be over-stated. Some power supplies are just plain noisy. Some power supplies are marginally stable and will work with some pedals (or combinations of pedals) and not with others. I have some Monoprice power supplies that are unstable powering a ROG Double-D. They work with everything else, but not that one. I'm now using a Caline CP-05 and it works great.
 

phi1

Well-known member
Pedalpcb always puts a diode in line to protect polarity. This way, if someone insert the wrong power (center positve), nothing happens because the diode blocks it. Many circuits (like the original Animal trace I saw on FSB) have a 1N4001 diode shunt to ground, which will burn up if you plug in the wrong power, and then you have a short which should trigger your supply to shut off. I guess it protects the circuit (I don't have first hand experience), but you end up with a burnt diode inside. Putting the diode in line is better because nothing burns up. The down side is the diode drops the voltage (could reduce headroom in some circuits). However, PedalPCB specifically always calls out 1N5817 for this position, which has a very low voltage drop, so the effect (if any) will be very insignificant for most circuits.

On the original Animal, the 56R is there to form a low-pass filter with the 47uF. This is meant to reduce any high frequency noise from the power supply. As noted above a halfway decent supply should have it's own noise filtering. I'm not sure why PedalPCB omitted the resistor, maybe he assumes you're using a decent power supply, or he's tested and found this resistor isn't actually that helpful for reducing noise.
 

phi1

Well-known member
Also, heads up, many people report the Animal is noisy (both the Rockett purchased one and diy builds on vero) when using it for high gain. I myself have experienced this, I helped a friend put together one on vero, and I tried everything I could think of to reduce the noise without much luck. At the end of the day I think it's because it has a less aggressive clipping arrangement than most distortions. So, to achieve equivalent distortion as a pedal like a rat or ocd, it has to amplify the signal more, and any noise from the guitar gets amplified as well.

The less aggressive clipping arrangement on the Animal consists of back-to-back pairs (2 diodes in each directions, so higher clipping threshold), which are in the op amp feedback loop (softer type of clipping like Tubescreamer). A Rat has 1 diode in each direction (lower clipping threshold), and they are shunt to ground (harder type of clipping). No doubt this arrangement contributes to the open sound that people love about the Animal, (along with the minimalist EQ filtering), but the trade-off is a higher noise floor for equivalent distortion.

If anyone has any experience to the contrary with Animal circuits, or ideas to reduce noise, feel free to share.
 

Frostbite Slim

New member
Hello on the PCB of Mammal (Animal), there not the resistor 56R as original schematic and there is a diode 1N5817 instead.
Can you explain this différence.
Thanks you in advance
I have this same question as I’ll be building this as soon as my PCB arrives. How essential is the 56R as in the original schematic, and the reason for its omission here
 

phi1

Well-known member
See my first response from Oct 2. Pedalpcb always sets up the power section the same way. I think you will be just fine to omit the 56R. In theory the 56R lowers the cutoff frequency that gets filtered, but in reality I don’t think people have issues with how pedalpcb sets it up.

Or if you want, you could solder the resistor in place of the diode, and omit the diode, or solder the diode in off-board.
 

Frostbite Slim

New member
Thanks again phi1. What about the 1k Input resistor that was added to aid with the filtering to the 220pf that’s on the FSB pages? Good idea or not necessary?
 

phi1

Well-known member
Seems like a good idea, you could try it out and see. The benefit would only be for filtering out high frequency radio station noise. Like I said in my other post, In my experience (and lots of folks online who have the original), this circuit tends to be fairly noisy. I don’t think this has to do with radio noise that the 1k/220p would eliminate, or power supply noise, but rather the circuit amplifies noise from you guitar significantly. The soft clipping arrangement with high threshold gives a nice, not very compressed clipping sound, but it requires a lot of amplification to get high levels of distortion, and thus the guitar noise is amplified a lot. That’s my take on it anyway after two builds and trying several things to tame the noise.
 

Elijah-Baley

New member
I got some squeal/whine issue with some fuzz circuit, still didn't solve.
My old Boss PSU has always worked fine, but sometime I got this issue, With a 47R or a 1N5817 in line to the 9v I always solved the problem.

But I built the circuits of a Woolly Mammoth and a Ultimate Octave (a modded Foxx Tone Machine) and those still whine too much. The Woolly Mammoth is almost quite, but not really silent. While I tamed the Ultiamate Octave just with a 330R resistor in line to the 9v, and this resistor seems to me too much high, tough I can't hear too much difference in the sound. I assume it's make at least a little difference.
I found (then lost) a page where there are all this filter methods, but the best was the one with an inductor in line with the 9v. I couldn't buy any inductor in this period and I still didn't try it.
Anybody knows this method?
 

phi1

Well-known member
Yes that’s fine, it’ll just have a different sweep. Audio taper is common for volume knobs anyways.
 

HamishR

Well-known member
Sometimes I like to use a B-taper Volume pot because it can give the illusion that there is a ton of level available. With an A-taper it seems like you have to turn it up more for the same result. I worry when I have to turn the volume up well past noon for unity so might swap from an A to a B to make myself feel better.
 

Frostbite Slim

New member
Build complete and sounds great! However, there is an LED issue. When the 2.1 plug is inserted in the DC Jack, the LED illuminates very dimly. This happens in Bypass mode. I also get a noticeable Pop when engaging pedal
 
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