Smoothie LFO noise.

[JakeFuzz]

This is a weird problem. I just built up a smoothie and used a 10K instead of the 4.7V zener. I also used a 10uF Tant cap instead of the 47uF electrolytic as the main filtering capacitor (saves space). I am getting LFO clicking on high gain pedals when the smoothie is off but connected to the same power supply (daisy chained onespot). The noise is barely, if at all, audible through most pedals except my MKII tonebender in which the clicking is almost as loud as the guitar signal. The MKII has always had a significant amount of background noise but never any clicking from LFO's.

I have tried the following:

Switching the order; I've put the MKII far away from the smoothie and before the smoothie in the chain. This doesn't help.

Battery power: This makes the clicking go away completely. I can power either the smoothie with the battery which makes any of the LFO noise that was in the chain disappear. I can also power just the MKII with the battery in which case the clock noise disappears completely and a very significant amount of white noise is removed from the full gain sound; in this setup there is still a VERY small amount of audible noise when the Klon or Rangemaster is on and at full tilt.

Increase the main filter capacitor: Ive added an additional 47uF electrolytic cap to the main power input of the smoothie or the MKII and this doesn't help at all.


This is definitely happening because of the draw on the supply rails but I was surprised to see that more filtering didn't help. I am wondering if I should increase the filtering even further on the smoothie (very limited space in the enclosure) or the MKII. I am also wondering if using the 4.7V zener (I think I have a 5.1V around here somewhere) will help with the draw. My last option is to power the MKII or the smoothie with a battery which would have to be attached to the bottom of the pedal board. I was surprised to see how much noise was reduced from the MKII when using battery power and I think this may be a better option anyways. The problem is now that I would have to make some crazy arrangement underneath the board to hold the battery, route the power to the pedal and have a disengage so I don't drain the battery.

Idears?

[JakeFuzz]

Well I found something that seems to work. I put a 120 ohm resistor in line with the supply and a 100uF cap to ground after that. The aggressive ticking is gone when the TB is on but there is still a faint woosh from the LFO. I am going to pick up a larger cap from work tomorrow and see if that solves it. I think a larger cap should be able to deliver the excess current the supply is drawing. I may try the same arrangement in the MKII to see if that cures the noise.

[madbean]

Did you try it with a non daisy chained supply just to see if the ticking went away? Current draw should not be to aggressive on it. Hmm. Maybe lowering the voltage divider resistors would help by increasing the current to the bias supply...like 10k instead of 150k on both. Or swapping it for a lower current draw IC like the TL062.

[JakeFuzz]

If I put the smoothie and TB on separate supplies it works well; no ticking and the noise is reduced in the TB. I think the TB is just extremely sensitive to changes in the supply voltage for some weird reason and those changes come through as noise.

I think a huge reserve cap and that small resistor should be enough for the smoothie to draw from. I have it at 100uF right now and the ticking is almost inaudible. I did look at the TL062 but I soldered the IC's in and don't want to unsolder the ones I have in there. They are TLE2072's and I think they draw even more than the TL072! Ill take a look at the 150k-150k divider if my reserve cap doesn't work.

[jimilee]

Would a shielded power supply work like a voodoo labs or even a lesser expensive one?