I want to increase the sensitivity on my McMeat (Meatball) clone

[hooya]

I built a Meatball clone using the McMeat project using joep's version 1.1 layout. All stock parts and values including the VTL5C3.

My concern is that I absolutely have to max out the volume on the guitar to get the effect to trigger even with the sense knob maxed out. I want to be able to dial the sense knob to about 2:00 and still have the effect trigger when my guitar volume knob is at a 7 or 8, so I have more headroom on both sides of the equation.

Any idea what component swap I could do? A different Pot value for the Sense instead of the stock 10K one maybe?

[Mark Hammer]

The simplest thing to do is change the 1M8 feedback resistor (R6) on the rectifier stage for a 2M2 value.  That will increase the gain of the envelope follower.

[Gus]

Have you tried your guitar with a real Meatball?

Are you sure you built the McMeat correctly?

[hooya]

I have never had access to a real meatball. It's possible that something is out of spec, but I can't really test to verify... I had never used it with guitar before (I was using it with bassoon, witch has a much different output than guitar) and it worked fine for that purpose.

My more high output pickups work better than the standard strat single coil.

There is one thing, on the decay of the strings I often get a warble sound as the filter closes off. Like there's some residual something happening. I've built 5 or 6 of these things though and they've all reacted exactly this way. So I don't think it's this particular pedal, it would have to be something in the design schem.

Edit: OK, I just watched some youtube videos and copied the settings to compare the sound. Everything works like it should as long as I have my guitar volume at a 9 or 10. Only thing different is my decay knob setting. I think my decay knob is weird though (it's audio taper, but it doesn't have a smooth travel, it's like it clicks into various positions... it's odd)
I assume that most guitarists probably at least do these demo videos with their volume maxed on their guitar, as I rarely have encountered a guitar player that usually leaves their guitar volume at a 5 or 6 and has room to go UP from the guitar level. I like to be at a 7 or so and then turn up if I want to overdrive. Saves me from building a boost pedal and gives me more playing flexibility. So I think I really do want more sensitivity. I'll try the resistor mod.

[Mark Hammer]

The "warble" is envelope ripple.  Guitar signals are intrinsically unstable and variable, so what the rectifier stage detects is not going to be a smooth up then down change.  The signal is most inconsistent during that period when the string is sustaining then decaying.  At the point when you pick, the string will be negligibly affected by things like body resonances, "beats", finger vibrato, and so on.  The variability that makes for envelope ripple starts to come into the picture after a few hundred milliseconds or so.

There are two ways to minimize audible ripple with a rectifier as simple as that used by the McMeat/Meatball.  One is to aim for a long decay time, so that all the little blips are smoothed/averaged out by a large value of C7.  The other way is to aim for as quick a decay as possible, so that the filter returns to its starting point well before any ripple is heard.

Another way is to have a more ideal rectifier/envelope detector, but that involves a redesign, so we'll set that aside.  For now, go fast or go slow.