Low Tide - Almost Working. Help?

Idlebeach

Member
Howdy partners. I am not a circuitry genius like it seems like a lot of people online are. Perhaps I am not skilled enough to finish this but I think with a few nudges this can be figured out. I have built quite a few pedals and troubleshot a bunch on my own but I am just not sure what to do here.

Here's where I am at. When the effect is engaged signal goes through and is -sort of- effected. I can get a sort of envelope filter Q Tron type sound from it. If I adjust the BBD trimmer I can get it to a point where it is distorted and then back off a bit. Sometimes it has a very subtle phasing type sound .but after I move the knobs around it seems to disappear? Most of the pots don't seem like they do anything aside from the gate(?) potand volume. The dip switches work, definitely notice a boost so that's good.

I subbed out a 2sk30 for the 2sk208 initially but later saw some people had luck with j201 - seems the same? I couldn't find bat48s so I think I used bat46's.. I used a surface mount version of the LM258P but I think I fried that but I have another one. I am curious if there are any common ICs I can swap the LM258P for - I have a decent variety of common ones. Not sure what it's doing in the circuit so I don't know how important it is to get the exact right one. I am also using a Panasonic MN3207 instead of the new cool audio one. Not sure how to spot if it's fake or not but I built a chorus with the same ones and it sounds great so I assumed it would at least function. Even swapped it out with a different one to make sure that wasn't the big issue. If it could be the major issue - anyone got one of the new MN3207's in a parts drawer they can sell to a pedal pal? 😜

Other than that I accidentally got a B1M dual gang but I am sure that will only effect the taper and I plan to replace it eventually - if I can get it working.

I apologize this was kind of a longer post and I can't offer up a ton of info to get started. I don't know if audio probing would help here - I have only been able to navigate it myself on much smaller simpler circuits so I don't know where to go on this big daddy. I have a DMM at the ready if anyone needs readings - just tell me where to go and what to do and I will do it!

Thanks so much. I hope someone out here can help me troubleshoot this. I feel like its got to be something really simple at this point.

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just incase the photos are small you can view them on imgr
 
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spilla

Member
If your using a j201 with an adapter board be sure you have the legs in the right orientation. I've got a similar issue with my low tide and I'm pretty sure this is the problem, unfortunately I fried my randomiser ic debugging. A replacement should turn up next week though.

Forum member bowanderror kindly pointed this out to me

The pinout of 2SK170 (through-hole equivalent of the 2SK208) is DGS, but the J201 pinout is DSG. I can't quite see from the photos, so make sure you've swapped the Gate & Source pins before placing it in the socket. To keep them from shorting out as you cross them over, you can use a piece of heat shrink tubing or a piece of stripped wire insulation on one lead

Edit: Cabintech have some v3207's
 
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zgrav

Well-known member
Don't assume part values and soldered connections are OK, since those can cause the things you describe. Detailed pictures of each side of your board and wiring will make it easier for you and for others to troubleshoot.
 

Idlebeach

Member
Don't assume part values and soldered connections are OK, since those can cause the things you describe. Detailed pictures of each side of your board and wiring will make it easier for you and for others to troubleshoot.
Sorry about the lack of photos! Looks like they are too big to attach here? Anyways here are some - Imgur photos .
 

zgrav

Well-known member
Do you have anything under the B1M to insulate it from the board? Looks like the solder side could also benefit from cleaning it with IPA and a toothbrush, but try to keep the liquid away from the pots.
 

Idlebeach

Member
Do you have anything under the B1M to insulate it from the board? Looks like the solder side could also benefit from cleaning it with IPA and a toothbrush, but try to keep the liquid away from the pots.
It's hovering quite a bit but I can add some tape. The pcb was clean right before the photos but I decided to try reflowing and it got looking like that again! I will clean it up when I get home.
 

Idlebeach

Member
If your using a j201 with an adapter board be sure you have the legs in the right orientation. I've got a similar issue with my low tide and I'm pretty sure this is the problem, unfortunately I fried my randomiser ic debugging. A replacement should turn up next week though.

Forum member bowanderror kindly pointed this out to me



Edit: Cabintech have some v3207's
Thanks for the heads up on Cabintech! Shipping looks super cheap if you only want a single part too which is killer. Picked up a couple just incase mine are janky after all.

Super odd on the legs. If I pop a j201 (smd on a board) into the through holes It works as is - if I swap the 2 appropriate legs (i check the data sheets to make sure which) it also works. No difference in sound though.

I may re order the lm258p.. Idk. I just really want to play around with it but I am trying to be really careful to not overwork anything. I will remain hopeful! Please keep in touch with me on if you get yours working. If it sounds like a similar issue I hope we can figure it out.
 

bowanderror

Active member
For the LM258, you can sub in LM358 or LM2904. I built one with 2SK30ATM-Y and it should work with the same pinout as 2SK208. I prefer the sound with the 2SK vs. J201.

If you set the Mix knob to 100% dry (no delay), does it sound similar to your bypass signal? That will at least rule out the preamp & post-amp sections.

Put some tape on the back of your dual-gang pot just to rule that out.

There is at least one pad that doesn't look fully soldered:
Low Tide pad copy.png

Lastly, your microcontroller (top left) looks a bit crispy and I'm wondering if it has let out its magic smoke. They are quite sensitive and only run on 3.3 or 5V, so it could be from a short circuit or overheating. I would use a multimeter & take voltages at each IC pin & at the JFET pins to post here. Set the BBD trimpot to around halfway for the measurements. That will let us know if everything is at least powered up correctly.
 

Idlebeach

Member
For the LM258, you can sub in LM358 or LM2904. I built one with 2SK30ATM-Y and it should work with the same pinout as 2SK208. I prefer the sound with the 2SK vs. J201.

If you set the Mix knob to 100% dry (no delay), does it sound similar to your bypass signal? That will at least rule out the preamp & post-amp sections.

Put some tape on the back of your dual-gang pot just to rule that out.
Hey! Thanks a bunch for all the stuff to check out! Unfortunately I cant find another 2sk30a in my parts stash right now but I did swap the 258 for an LM358. I removed the dual gang and put some electric tape and hit all the parts under with the iron again and added a little more solder. Cleaned up the board a bit. It behaves the same so far. All worth a try!

I assume you are talking about the "tiny" chip (I think it's the randomizer. I took readings from it to let you take a look.
  1. 4.7v
  2. 5.02v
  3. 5v
  4. 0v
  5. Fluctuates around 2v-ish
  6. 5.02v
  7. 5
  8. 5.02
For the J201 that is meant to be a J201 I have
D. 4.89v
S. 0.22v
G. 0v

For the J201 I have in place (with twisted but heat shrunk legs) in place of the 2sk208
S. 0.29v
D. 7.21v
G. 0v

As far as the pots - I forgot to do what you said exactly but The volume definitely boosts. and I can have an unaffected but louder signal if I want.

I really hope I did all that right. I will try everything you suggest so long as I have the tools/parts/can find replacements. Thanks again!
 

bowanderror

Active member
Those voltages look pretty good, but don't necessarily tell us if the randomizer IC is working. How does the voltage on pin 5 of the randomizer change as you adjust the Rate knob? If it steps very slow when the knob is down & gets faster as you turn it up, the IC is probably fine.

The amount of effect & it's response to your playing is somewhat limited by the internal trimpots. How did you set the BBD Bias & Gate trimpots? Here is the info:
  • BBD/BIAS trim pot - Similar to the pot on a CE-2 or Caesar. Adjust for the least amount of distortion with modulation. Pretty obvious when set correctly. Set the Depth to 100% and turn up the output loud enough to clearly hear the signal. 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. Just set the trimmer for the least noise.
  • GATE trim pot - User preference, it controls the frequency of the low pass filter portion of the gate - Set MIX to 100% wet, LPG 0%, Depth 0%. Turn Gate Trim CW, you should hear the filter "open up" as you turn it up. You want to set the Gate Trim so the LPG knob goes from completely off at 0% to completely open at 100%, with a good amount of different settings in between - “I did have to fiddle with the external gate pot on mine to get a setting where I could hear the chorusing clearly, you may have to play around a little to get it completely tuned in”
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.

If you're still not getting any effect after that, you can either make an audio probe & trace the signal, or post the voltages for the other ICs.
 

spilla

Member
Theres a small discrepancy on the photo on the main page, it looks like r15 was printed twice (though the screen printed values on the boards are correct). Just check you have the correct values here, i cant quite tell by looking at your pics.
 

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Idlebeach

Member
Theres a small discrepancy on the photo on the main page, it looks like r15 was printed twice (though the screen printed values on the boards are correct). Just check you have the correct values here, i cant quite tell by looking at your pics.
Hey! My PCB actually has part values printed on the board. I still took the parts off to check and it seems like they are/were correct. That is a keen eye though!

Also general update to anyone who sees this later. I think my low tide is basically working now? I can see that I definitely want to swap that dual gang out for the right taper. You might be wondering what I did differently or what I changed and I don't really know. Perhaps I re flowed solder to a part or maybe it was me not paying attention to what the knobs actually do and turning everything all the way to one side or the other to test it.

It seems like - to me at least - there are combinations of knob settings that seem to bring the effect out a lot more and the rest of the time it's very subtle. I could tell the chorusy sound was happening but very very subtle. I did get the cool audio version ordered so I imagine within 3-4 days I can swap the chip and see if it makes a difference.

If it is relatively subtle then I think we're good. Of course if I turn the slew back, turn the wet up and change the speed it rapidly gives me all kinds of weirdness that I can dial back. I have a feeling after I change the dual gang and maybe the MN chip I will be good to go..

Thanks a bunch to everyone who gave me things to look for! You are all delightful. :)
 

Idlebeach

Member
The amount of effect & it's response to your playing is somewhat limited by the internal trimpots. How did you set the BBD Bias & Gate trimpots? Here is the info:
  • BBD/BIAS trim pot - Similar to the pot on a CE-2 or Caesar. Adjust for the least amount of distortion with modulation. Pretty obvious when set correctly. Set the Depth to 100% and turn up the output loud enough to clearly hear the signal. 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. Just set the trimmer for the least noise.
  • GATE trim pot - User preference, it controls the frequency of the low pass filter portion of the gate - Set MIX to 100% wet, LPG 0%, Depth 0%. Turn Gate Trim CW, you should hear the filter "open up" as you turn it up. You want to set the Gate Trim so the LPG knob goes from completely off at 0% to completely open at 100%, with a good amount of different settings in between - “I did have to fiddle with the external gate pot on mine to get a setting where I could hear the chorusing clearly, you may have to play around a little to get it completely tuned in”
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.
The gate pot has an effect on the chorus? Perhaps I really need to dial this in more with the trim pot. I think right now I have it at what I would call maybe 2 o clock? It sounded more like a filter and not so much like it was gating and chopping off sound. I might need to hear more demos to see what it's supposed to sound like.

The BBD is a little more obvious. I turned it up and I heard the fuzz - I dialed it back and try to see if there is any particular sweet spot. Seemed like there was a lot of wiggle room.

The trim info is really useful! Thanks for posting that.
 

bowanderror

Active member
Glad to hear it's (mostly) working! 9 times out of 10 its a wiring mix-up or a solder joint, so reflowing can really help. I would call the effect gentle or soft, but not subtle. If it sounds subtle, you probably need to get the Gate dialed in better. I definitely recommend doing all of your testing & trimming with the Mix at 100%. That should give you the most responsive swell & filter on the chorus/delay signal.

The Gate knob refers to a Low-Pass Gate (LPG), which is a combination of a Low-Pass Filter (high frequencies removed) and a Gate - which "turns down the volume" until a strong enough signal triggers it open. The Gate has pretty slow attack & release, so it sounds like a volume swell. The actual set up is usually just a Low-Pass Filter that can sweep to the subsonic range where we can't hear, so at the bottom end of the filter sweep, where it closes, the volume level also drops. This means that the Gate knob controls how much of the chorus sound you hear in response to your playing.

I prefer to set GATE Trim to keep the LPG mostly open when the Gate knob is high, and to keep it mostly closed when Gate knob is low (only playing should open it). Try adjusting the GATE Trim with Mix 100% Wet & the Gate knob at various settings to get a good range.

Another thing to remember is that the LPG is VERY sensitive to your input signal, which is why the preamp has those DIP switches. If you have to play really hard to get it to open, try using the Boost switch. If it seems like it opens way too fast, or stays open, try the Pad switch. There is a lot of variability depending on your guitar, or which pedals you have before the Low Tide.
 
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