# Power Filtering in Mach 1 Circuit



## debrad (Jul 21, 2022)

A while back I built a PedalPCB Mach1 for a friend of mine and was recently reminded how great the circuit sounds.  Knowing that the component count is relatively low, I looked into a couple of vero layouts and noticed that the one found here:









						Greer Amps Lightspeed OD
					

Verified by dragão.




					dirtboxlayouts.blogspot.com
				




omits the two 22uf capacitors in the power section (C100 and C101).

I think it was @Chuck D. Bones who mentioned these are "power filters" in another Mach1 thread but I thought I would ask for some more details on their function as well as ask for confirmation on whether there are any pros/cons to including or omitting them from the circuit.

As always, your kind and generous contributions to increasing my knowledge on all things pedal (and electronics) related are MUCH appreciated!


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## Brett (Jul 21, 2022)

The linked board appears to use two 100uF capacitors in place of the two 22uF that are used in the PedalPCB board. The difference between the two values when used in this application (power supply section) will have a negligible impact on sound. 22uF is likely more than sufficient for this application. Have a look here: https://forum.pedalpcb.com/resources/circuit-design-power-supplies.8/ for more in-depth explanation of these components.


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## spi (Jul 21, 2022)

The short answer is they remove any AC ripples or noise in your DC voltage supply.


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## debrad (Jul 22, 2022)

Thanks for the replies (and the link to the power supply discussion, that was helpful!).

Based on your comments, I went back to the vero layout for review and can now see what  @Brett sees in terms of the two 22uf filter caps being REPLACED by two 100uf caps.  Sounds like I'm probably safe choosing either option but now I'm curious to know if there are reasons why one might choose one over the other?


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## spi (Jul 22, 2022)

It's common to use a larger (like 47-100uf) for the first filter and a lower one (10-22uf) for the voltage divider filter.  Why use a lesser value on the divider?  This I'm not sure.

You'll also see that some throw in another 100nf to filter out the higher frequencies that electrolytic caps are not as good at.


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## debrad (Jul 22, 2022)

Would it be wiser for me to just stick with one of the two options I've already been given or split the difference (i.e. 47uf rather than 22uf or 100uf)?


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## spi (Jul 22, 2022)

If you want another's take on it check the effectslayout version of the Lightspeed.  They use 100uf for the first one, and 10uf for the voltage divider one.
That's probably what I would use since it's very common to use this arrangement.


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## HamishR (Jul 23, 2022)

If it helps here is my take on the layout. I built it - it works. The filter caps won't affect the sound much (although I think they can a little!) so don't worry about it too much. And I noticed one of the comments on that page saying how much it sounded like a Timmy. It should. It's basically a Timmy with the Bass and Treble removed and a simple treble cut to replace them. I don't really see the point, but if it sounds good to you then that's all that really matters!


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## debrad (Jul 23, 2022)

Thanks @HamishR, your points are well taken...especially since I've read similar comments about the Timmy connection and I already have a rehoused "V1" Danelectro Transparent Overdrive in my collection (not to mention recent builds of OTHER "transparent overdrives" like the ODR1 and Klon).

I may still go down the Greer path but over the last couple of days I've started thinking that I might try adding a switch that would allow me to REMOVE the extra clipping diodes from a Southland rather than ADDING the extra clipping diodes to a Lightspeed.

Regardless of which way I go, this discussion has been great for enlightening me on what the main components are doing inside the power supply portion of these circuits.


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## HamishR (Jul 24, 2022)

There are tiny things I change which make me happy. Little annoying things that others may actually like or more likely not even hear! For example I just put an 820pF cap across the base and collector of a silicon transistor in V2 of my modified Broadcast to reduce the treble a tiny amount. It worked so I am happy and will be more likely to use the pedal now. A friend of mine has the original pedal and doesn't even notice the extra treble which drives me crazy!

None of this stuff really matters to anybody except the person playing the guitar.


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