Low Tide Whistling and Noise/Hiss

[93ryans]

Hey all, I just finished this build last night. It seems to be working for the most part, but with a couple issues. One of which I gather has been talked about before and may be more of a feature than a bug, namely the BBD hiss.

What I'm more worried about is that I get this weird, high-pitched, oscillator sounding background noise that jumps around a lot when the gate is open. It doesn't happen when the LPG is closed (so I hear it most when the LPG pot is all the way up), and it doesn't happen when there's no noise going through the circuit. It seems to be related to the BBD the same way the hiss is, but also possibly related to the Randomizer.

Here's a cell phone recording I took to demonstrate. Please don't mind the clicking sound, I believe that's just the footstool I was sitting on. There's no fan running or anything, so the hiss you hear here is mostly from the pedal as well. I mention the hiss as well because even though I know it's a feature of the original pedal, I wonder if mine isn't particularly loud... It happens both with and without the boost activated. I've screwed with the BBD trimpot a bit and it has a definite effect on both sounds. I'll have to fine-tune it a bit more though to see what I can do.

I got my V3207D's from Cabintech, via Ebay. I'm led to believe they're pretty reliable distributors.

I'm very close to finishing a Low Tide Mini as well at the moment, so I'll compare the two once it's done. Shot in the dark, but is there any difference between the Randomizer IC's shipped with the two versions? Cause it's very possible I switched them.

Lastly, could someone explain like I'm five, exactly what the BBD trimpot controls? I'm not especially clear on that at the moment.

Thanks for reading!

EDIT: The same noise happens both on my daisy chain (this was the only thing plugged into it) and on my Voodoo PP3 power supply. Both of those were plugged into the same power strip, but the PP3 being an isolated supply I didn't think that would make as much diff. Still, I'll try other power configurations and let yall know.

 

[Robert]

The Randomizer microcontroller is interchangeable between the full/mini version.

Have you adjusted the BBD and GATE trims? It can be noisy if the gate trim is all the way open.

 

[93ryans]

The Randomizer microcontroller is interchangeable between the full/mini version.

Have you adjusted the BBD and GATE trims? It can be noisy if the gate trim is all the way open.

Thanks for the quick reply. I have adjusted both of them a bit, but I didn't think to mess with the Gate one much.

I almost forgot about it since I was focused on the noise and BBD, but when I first powered the circuit the Gate was set low enough that none of my guitar was getting through when it was closed. I think I wrenched it up to where I could here my guitar when it was filtered and called it that. But I'll see if I can't fine-tune them both and see if it solves the ish. I'll have to report back on that in a few hours though.

 

[93ryans]

A'right, here's where tuning the trimpots got me:

I tuned the Gate trim with the LPG fully closed, and found that I get no guitar at all coming through below around 2 o'clock, so it needs to be pretty high to get anything. I tuned with BBD trim with the LPG fully open, and honestly had a really hard time picking out meaningful differences. It causes some pretty ugly distortion at the extreme ends, and a noticeable amount above 2 o'clock or so. I'm leaving it around 11 for now.

Are these behaviors expected? Should I double check some component values or anything?

 

[bowanderror]

A'right, here's where tuning the trimpots got me:

I tuned the Gate trim with the LPG fully closed, and found that I get no guitar at all coming through below around 2 o'clock, so it needs to be pretty high to get anything. I tuned with BBD trim with the LPG fully open, and honestly had a really hard time picking out meaningful differences. It causes some pretty ugly distortion at the extreme ends, and a noticeable amount above 2 o'clock or so. I'm leaving it around 11 for now.

Are these behaviors expected? Should I double check some component values or anything?

I also had trouble getting the Gate & Bias trimpots set properly and ended up collecting a lot of info on setting them. I've underlined the step below, but you'll want to test the range of your LPG control each time you adjust the Gate trimpot. Unfortunately, both trimpots have quite narrow usable ranges (especially the Gate trim), so make very, very small adjustments with a screwdriver:

BBD/BIAS trim pot - Set for loudest, cleanest sound

1. Set your Slew control to 0%, Mix, LPG, & Depth to 100% and Rate to ~50%
2. Set both DIP switches to their OFF positions (to the left on your pic) - You can choose which DIP switch to use after setting up the Gate trimpot, but you should only be using either the Boost OR the Pad switch, not both at the same time.
3. Turn up the Level control to where it's loud enough to clearly hear the signal
4. Start with the trimmer at noon (50%) and gently adjust right & left to find the "sweet spot" where the signal is the loudest & has least amount of distortion. There is a range on the trimmer where you will hear the chorus/delay effect. At either end of the range, there is quite a bit of fizz. Pretty obvious when set correctly, just set the trimmer for the least noise & fizz.

GATE trim pot - User preference - Controls the frequency of the low pass filter portion of the gate, and how much it's envelope is triggered by your input signal (interacts heavily with external LPG control)

1. The Boost & Pad DIP switches will change the sensitivity of the LPG to your guitar signal, so decide if you want to use either before setting the Gate trimpot. Otherwise, keep them both OFF - I keep the Boost switch ON at all times, because it has a more drastic effect on the LPG, and the preamp has a nice lofi sound.
2. Set Mix to 100% wet, LPG & Depth to 0%.
3. Set the Gate trimpot to 0% to start.
4. Slowly turn Gate trim clockwise, you should hear the filter "open up" as you turn the trimpot up.
5. After each Gate trimpot adjustment, try the external LPG control at settings of 0%/50%/100%. You want to set the Gate trim so the external LPG knob goes from completely off at 0% to completely open at 100%, with a good amount of different settings in between.

GATE trim setup from Fairfield Shallow Water Manual:

• LPG ADJUST (i.e., GATE TRIM) - The recovery filter’s lowest frequency can be adjusted, to fine tune the way it will react to incoming signals. Lowering this frequency emphasizes the action of the low pass filter, effectively raising the threshold of sensitivity. Adjustment should be made with the following settings: MIX full wet, LPG minimum, DEPTH minimum. While listening to a signal going through the pedal, you’ll hear the effect of the recovery filter at its resting state. Carefully turn the trimpot labelled LPG adjust (i.e., GATE TRIM), clockwise to raise the filter’s frequency, counter-clockwise to lower. Be very careful, adjustments should be minimal as the trimpot is very sensitive. After each adjustment, LPG should be turned up momentarily to listen at the envelope’s response to the incoming signal.

 

[93ryans]

I also had trouble getting the Gate & Bias trimpots set properly and ended up collecting a lot of info on setting them. I've underlined the step below, but you'll want to test the range of your LPG control each time you adjust the Gate trimpot. Unfortunately, both trimpots have quite narrow usable ranges (especially the Gate trim), so make very, very small adjustments with a screwdriver:

BBD/BIAS trim pot - Set for loudest, cleanest sound

1. Set your Slew control to 0%, Mix, LPG, & Depth to 100% and Rate to ~50%
2. Set both DIP switches to their OFF positions (to the left on your pic) - You can choose which DIP switch to use after setting up the Gate trimpot, but you should only be using either the Boost OR the Pad switch, not both at the same time.
3. Turn up the Level control to where it's loud enough to clearly hear the signal
4. Start with the trimmer at noon (50%) and gently adjust right & left to find the "sweet spot" where the signal is the loudest & has least amount of distortion. There is a range on the trimmer where you will hear the chorus/delay effect. At either end of the range, there is quite a bit of fizz. Pretty obvious when set correctly, just set the trimmer for the least noise & fizz.

GATE trim pot - User preference - Controls the frequency of the low pass filter portion of the gate, and how much it's envelope is triggered by your input signal (interacts heavily with external LPG control)

1. The Boost & Pad DIP switches will change the sensitivity of the LPG to your guitar signal, so decide if you want to use either before setting the Gate trimpot. Otherwise, keep them both OFF - I keep the Boost switch ON at all times, because it has a more drastic effect on the LPG, and the preamp has a nice lofi sound.
2. Set Mix to 100% wet, LPG & Depth to 0%.
3. Set the Gate trimpot to 0% to start.
4. Slowly turn Gate trim clockwise, you should hear the filter "open up" as you turn the trimpot up.
5. After each Gate trimpot adjustment, try the external LPG control at settings of 0%/50%/100%. You want to set the Gate trim so the external LPG knob goes from completely off at 0% to completely open at 100%, with a good amount of different settings in between.

GATE trim setup from Fairfield Shallow Water Manual:

• LPG ADJUST (i.e., GATE TRIM) - The recovery filter’s lowest frequency can be adjusted, to fine tune the way it will react to incoming signals. Lowering this frequency emphasizes the action of the low pass filter, effectively raising the threshold of sensitivity. Adjustment should be made with the following settings: MIX full wet, LPG minimum, DEPTH minimum. While listening to a signal going through the pedal, you’ll hear the effect of the recovery filter at its resting state. Carefully turn the trimpot labelled LPG adjust (i.e., GATE TRIM), clockwise to raise the filter’s frequency, counter-clockwise to lower. Be very careful, adjustments should be minimal as the trimpot is very sensitive. After each adjustment, LPG should be turned up momentarily to listen at the envelope’s response to the incoming signal.

That's fantastic, thanks a ton! I'll be going through those steps just as you say.

Sorry to hammer a point, but I'm a bit hung up on it and want to verify: has it been your experience that having the gate below noon or so eats all of a guitar's signal when the LPG is at 0%?

 

[bowanderror]

That's fantastic, thanks a ton! I'll be going through those steps just as you say.

Sorry to hammer a point, but I'm a bit hung up on it and want to verify: has it been your experience that having the gate below noon or so eats all of a guitar's signal when the LPG is at 0%?

It depends on how you prefer to have it set up, but yes.

The way my Low Tide Gate trimpot is set, there is little to no signal coming through with LPG at 0%. I prefer this as it gives me everything from signal only peaking through with hard playing when set to 0% all the way to the LPG basically off at 100%.

The Gate trimpot determines the range of the LPG control, and the LPG control determines how responsive the LPG is to your input signal.

BTW, you'll get less hiss if you turn off the "Boost" DIP switch (the boost setting is kinda noisy). You should set your Gate & Bias trimpots with whatever DIP switch settings you intend to use. If you change the DIP switches, then you may have to tweak the trimpots again. I've seen a few people that have both the "Boost" and "Pad" DIP switches turned on, which doesn't make any sense. It should just be one or the other, or neither (a good place to start).