SOLVED Low Tide distorts signal and too loud.

[LJSJS]

I built the Low Tide PCB, but it produces very strong distortion and the sound is too loud. I’ve tried adjusting the BBD Bias trimpot and Gate trimpot, but the issue persists. Notably:

1. The distortion and noise still occur even when the Mix knob is set to 0.
2. The modulation does not seem to work at all.
3. The gate function works, but when it engages, the volume increases significantly.
4. There are no issues or noise when the guitar is not being played or when the pedal is bypassed.

Currently, I’m diagnosing the distortion issue by measuring voltages at key components, but this is my first time working with circuits, so I’m not sure how to determine if the values are correct. Here are the voltages I measured so far:

Q1 - 2SK208-Y:

• Source: 4.96V
• Drain: 0.3V
• Gate: 0

Q2 - 2N3904:

• Collector: 8.7V
• Base: 4.96V
• Emitter: 4.33V

Q3 - 2N3904:

• Collector: 5.15V
• Base: 4.07V
• Emitter: 3.54V

Q4 - J201:

• Source: 0.21V
• Drain: 5.1V
• Gate: 0

Q5 - 2N3904:

• Collector: 8.7V
• Base: 5.12V
• Emitter: 4.46V

IC1 - LM78L05:

• Input: 8.7V
• Ground: 0
• Output: 5.04V

IC2 - Randomizer:

• Pin 1: 4.71V
• Pin 2: 4.61V
• Pin 3: 5.01V
• Pin 4: 0
• Pin 5: 5.04
• Pin 6: 5.01
• Pin 7: 5.03
• Pin 8: Moves randomly from 1 to 4

IC3- LM13700N:

IC4 - LM258P:

• Pin 1: 0.01
• Pin 2: 2.51V
• Pin 3: 2.5V
• Pin 4: 0
• Pin 5: 8.7
• Pin 6: 2.14
• Pin 7: 2.14
• Pin 8: 2.14

IC5 - MCP602 I/P

• Pin 4: 0
• Pin 8: 2.14

IC6 - CD4046BE
IC7 - V3207D

Some of the ICs have fluctuating values, so I wasn’t able to get consistent measurements.

If there’s anything I might have missed or additional steps I should take, I would greatly appreciate your advice.

 

[BrainDrain]

There needs to be something separating the dual gang pot from the pcb. Like a small slip of cardboard taped into place so the pot doesn’t touch the back of the pcb.

The two threads below should help. If neither of these procedures work then it’s probably a component issue like a wrong resistor value or could possibly be a defective trace on the pcb. It’s most likely something else but my low tide pcb had two bad traces so it’s always possible. I just used a multi meter to check continuity between points until I found the traces that were broken. I’d try the setup procedures first, then check all your resistors if that doesn’t work.

SOLVED Post in thread 'Low Tide - LPG not working.'

Jul 1, 2022

The envelope part of the LPG does indeed send a control signal to the LM13700. It's actually a control current, but I believe you should see a change in voltage if you probe after R29 (at Pin 1 & Pin 16 of the OTA). Both pins are connected, and the voltage should change as you play harder. I can't recall offhand what the voltage range is, so maybe someone else can chime in.

I know you said you played with the trimpots, but I'd go through the process below word-for-word as there is a lot of interaction between the front panel controls & the trimpots. Unfortunately, they both have quite...

• bowanderror

• 

J

SOLVED Post in thread 'Low Tide (Full Size) Oscillator problem'

Jul 17, 2024

Ok, new update. I ordered a new pcb and started over. I was 100% sure all my values were correct per the documentation. I also made sure to use sockets instead of soldering IC's directly to the board in case I needed to replace one or more with no risk to damaging the PCB. I got very different results this time and everything worked out for me. Here are my notes on dialing in the trimpots:

1. Do the GATE adjustment first - Set the mix to 100%, Depth and Slew to zero and Volume all the way up. Start with the trimpot all the way turned to the left and slowly turn it up. Plug in a guitar and...

• Jachiro

• 

 

[swelchy]

if you have a 3d printer or have a friend you can squirt these out I shared a file on thingiverse for peeps..
3d Print Dual gang pot covers

 

[BrainDrain]

if you have a 3d printer or have a friend you can squirt these out I shared a file on thingiverse for peeps..
3d Print Dual gang pot covers

That’s cool! Nice job

 

[LJSJS]

I tried fine-tuning the trimpot, but unfortunately, it didn’t work out. Think diagnosing the issue is going to take longer than I expected. Since I don’t have a 3D printer, I picked up some duct tape instead. By the way, that pot cover idea looks super effective! I’ll also need to spend some time checking whether the resistor values are correct. Thanks again for your support!

 

[comradehoser]

You should probably check values and correct orientation of all components. Failing that, it's probably a good idea for an audio probe.

 

[BrainDrain]

I tried fine-tuning the trimpot, but unfortunately, it didn’t work out. Think diagnosing the issue is going to take longer than I expected. Since I don’t have a 3D printer, I picked up some duct tape instead. By the way, that pot cover idea looks super effective! I’ll also need to spend some time checking whether the resistor values are correct. Thanks again for your support!

I checked all your resistors and they look correct. I’d try the audio probe or a multi meter that has a continuity setting next. Where did you get the 3207? It’s hard to see the writing on top in the picture so I can’t tell if it’s a Coolaudio brand.

Just a few suggestions for your next build to make things easier to diagnose if needed.

1: the fat brown bands (tolerance color) on one end of the resistors should all be lined up so if you have to check them it’s much easier to look at

2: IC sockets. Prevents any over heating of the IC from soldering and it’s easy to pop them out and try another if there’s an issue.

Also when writing down IC voltages the IC is numbered like this:

 

[Robert]

If you have noise/distortion with the mix control at zero you can eliminate about 80% of the circuit.

You're looking for an issue between the input and Q2, or between the mix pot and the output (Q4 / Q5).

You can ignore the 3207, microcontroller, LM13700, and fooling with the trim pots until you get a clean signal with the Mix control down.

They're both SMD so that's a good sign, but just to be sure, did you get your 2SK208 and J201 from reliable sources?


Here:



Or here:

 

[LJSJS]

I checked all your resistors and they look correct. I’d try the audio probe or a multi meter that has a continuity setting next. Where did you get the 3207? It’s hard to see the writing on top in the picture so I can’t tell if it’s a Coolaudio brand.

Just a few suggestions for your next build to make things easier to diagnose if needed.

1: the fat brown bands (tolerance color) on one end of the resistors should all be lined up so if you have to check them it’s much easier to look at

2: IC sockets. Prevents any over heating of the IC from soldering and it’s easy to pop them out and try another if there’s an issue.

Also when writing down IC voltages the IC is numbered like this:

Thank you, especially for pointing out the importance of lining up registers properly. As a beginner builder, I can see how crucial that is. The V3207 I used is indeed from Coolaudio. I had to desolder it after soldering it in the wrong position, which caused some scratching. I suspect it might have overheated during the process as well.

 

[LJSJS]

If you have noise/distortion with the mix control at zero you can eliminate about 80% of the circuit.

You're looking for an issue between the input and Q2, or between the mix pot and the output (Q4 / Q5).

You can ignore the 3207, microcontroller, LM13700, and fooling with the trim pots until you get a clean signal with the Mix control down.

They're both SMD so that's a good sign, but just to be sure, did you get your 2SK208 and J201 from reliable sources?


Here:
View attachment 86026


Or here:
View attachment 86027

Thank you so much! This really helps narrow down the potential causes. I believe I sourced the components from reliable suppliers, but it’s possible they might have been damaged during the soldering process. I’ve already tried replacing the J201, and perhaps replacing other components along the problematic path might yield better results.

 

[comradehoser]

Thank you so much! This really helps narrow down the potential causes. I believe I sourced the components from reliable suppliers, but it’s possible they might have been damaged during the soldering process. I’ve already tried replacing the J201, and perhaps replacing other components along the problematic path might yield better results.

Hey bud, I just built another low tide to give away to the daughter of a friend and had similar issues to you: distortion through the range of the mix pot, although my volume was too quiet.

I looked at all components and orientation, replaced all the transistors, no dice. Then, I hit the 2sky and j201 SMDs again for a couple of seconds with some liberal application of flux around the legs and a little extra solder.

That solved the issue, 100%. Second build where I've had funky results be the fault of problems in my SMD soldering.

Try it, maybe it will work for you!