Sea Horse Mods

[Chuck D. Bones]

As requested, here are the mods I performed on my Sea Horse to increase the delay, increase the SHAPE range, improve the filtering, change the LFO speed range and one or two other things. It does everything that the Sea Horse and Dark Rift do, but with better filtering. These mods assume you are building on the revised Sea Horse board, dated 01-06-20. That board has the LFO tick fix built-in. You can perform all mods or any combination; one does not depend on the others. Here's a hi-res photo of my modded board for guidance on parts placement. Note: this was the previous rev board, so one or two parts may have moved.



Delay Mod
This mod extends the max delay time out to about 660ms (DEPTH set at zero). Optional.
Change ANIM pot from B2K to B50K. It's now called TIME. NOTE: Maxing both TIME & DEPTH can cause glitching in the delay chip, it's normal. Back off a little on one or both and the glitching goes away.
Delete R11.
Add a 33K resistor from ANIM-1 to DEPTH-2.
Change R7 from 2.2K to 1.5K.

Filter Mod
This mod re-tunes the input anti-alias filter (LPF1) and routes the delayed signal thru the output filter (LPF2). Recommended.
Change C7 from 1uF to 10uF.
Change C17 from 100pF to 220pF.
Add a 6.8nF cap from the right-hand side of R3 to the right-hand side of R33 (verify that the right-hand side of R33 is ground, I don't have the latest board).
Change R4 from 33K to 22K.
Delete R13 and C15.
Connect a wire from C15- pad to DIM-3.
Change R14-R18 from 10K to 47K (I used 51K, but either will work, just make them all the same).

Feedback Mod
This mod limits the signal amplitude when FEEDBACK (DIM) is maxed and the delay goes into self-oscillation. These diodes are built-in on the Dark Rift. Recommended.
Add 1N4148 diodes back-to-back from DIM-1 to DIM-2.

LFO Rate Mod
This mod changes the LFO speed range to 0.1Hz - 10Hz and improves the RATE control sweep. The slower rates are desirable when using longer delay settings.
Change R25 from 10K to 22K.
Delete R22 & R23.
Change R26 & R27 from 10K to 33K.
Change R34 & R35 from 100K to 10K.
Change C20 to 1uF film.

LFO SHAPE Mod
This mod extends the SHAPE range further into the square wave territory, allowing more abrupt sweeps and stronger pitch shifting when SHAPE is maxed.
Totally optional.
Change SHAPE pot from A100K to A250K.

 

[Dan M]

Thank you for taking the time to post this, and for calling out the “recommended” changes.

 

[Cvoxdog]

Hi Chuck, I took a chance and tried all your mods eve n though I have the newest version sea horse. It works but I noticed that the dimension knob doesn’t do anything. That should control the repeats right? I’ve been only getting one repeat. Any tips?

 

[Chuck D. Bones]

Start with visual inspection. You're looking for a bad solder joint, missing or wrong value part. Focus on the DIM pot, R9 & C10. If that doesn't reveal the problem, review the Build Docs and mod descriptions, then visually verify that all mods were performed correctly.

If that doesn't solve the problem, then start a thread in Troubleshooting. Post detailed pictures of both sides of the board. If you're good with reading schematics and have an audio probe, then check the various points along the feedback path.

 

[Cvoxdog]

Thanks for the reply, I’ll take a look!

 

[Cvoxdog]

Ok you are very smart and I am not. It was r9. I originally noticed that I missed that resistor after I boxed it all up and then just soldered it in with it boxed up. I thought the connection was good but after I just took it apart I noticed one leg was not attached! Now the pedal does what it’s supposed to and is more fun. Definitely recommend these mods to anyone building this!

 

[ADAOCE]

Boneyard edition board candidate?

 

[Chuck D. Bones]

Ok you are very smart and I am not. It was r9. I originally noticed that I missed that resistor after I boxed it all up and then just soldered it in with it boxed up. I thought the connection was good but after I just took it apart I noticed one leg was not attached! Now the pedal does what it’s supposed to and is more fun. Definitely recommend these mods to anyone building this!

Cool! Glad you found it so quickly. Missing solder joints happens to all of us. Visual Inspection is the #1 troubleshooting tool! One thing I've started doing is shining a bright light thru a soldered board and looking for holes where solder should be. I do this last thing before installing the pots.

 

[chongmagic]

Cool! Glad you found it so quickly. Missing solder joints happens to all of us. Visual Inspection is the #1 troubleshooting tool! One thing I've started doing is shining a bright light thru a soldered board and looking for holes where solder should be. I do this last thing before installing the pots.

Great idea, I actually finished a pedal a few days ago and it wasn't working correctly. It was bothering me and I couldn't get it out of my head. All of a sudden, I thought I probably missed a solder joint. Next morning I checked and voila it was the issue.

 

[Cvoxdog]

I hate to be the problem guy but I noticed after I hooked it up a louder amp that I’m getting the dreaded lfo tick but only when the pedal is bypassed. This is the newest version board so it should have the lfo fix built in. I tried moving the in out and jack wires and tried touching a 10nf cap on pins of ic4 without any luck other than being able to short out the lfo completely. I desoldered one leg of c19 to see if that would help and it sounds like that has to stay in. Any ideas as to other things I can try?

 

[zgrav]

do you get the noise when the seahorse is moved to a different place in your effects chain (assuming there is another spot)? Does the noise go away if the seahorse is the last thing before your amp? You could try shielding the wires going to and from the jacks to the footswitch. only attach the shield to the ground on the jacks.

 

[Cvoxdog]

Is there a good link for shielded wire I could buy?

 

[zgrav]

Here is a possibility from an ebay seller. Probably a safer purchase than an out-of-production transistor. : ^ )

 

[Cvoxdog]

Thanks for the link. I actually just got some Russian transistors and diodes from eBay today. Took 3 months! I wasn’t sure if they were ever coming. For the sea horse, I added a 100r resistor in series with a 220uf cap from the power supply and the negative end to ground. I think it decreased the noise compared to before. Shielded cables would probably do the rest.

 

[teal]

Hi Chuck,
I have a little question:
What does the Filter Mod do with the sound?
I have built a Sea Horse (without the mods, because I see them yet) and it has too much white noise in the wet signal for my taste.
Is the filter mod reducing the noise in the signal too?

 

[Chuck D. Bones]

The filter mod reduces some of the quantization and aliasing noise in the wet signal. It won't cure a noisy PT3299. I'm told some chips are noisier than others. Long delay settings are noisier, that's the nature of the beast. The dry signal is not filtered.

 

[teal]

Thanks.
I will give it a shot!
I have also a little whistling oszillation in the wet signal if I don't play anything.
If I play it turns into noise.
Hope it becomes a little better with the mod!

 

[Chuck D. Bones]

If your PT2399 is in a socket, try changing to a different chip and see if the noise changes. If you're using a power adapter, try a different one or a battery. The whistling noise you describe is not normal; don't expect the filter mod to fix it.

 

[teal]

You were right it was the chip.
Bought a bunch of PT2399 and with one of it there were no noises on the effect anymore.

 

[teal]

I tried the Delay Mod and I realize that I would like to prefer a shorter delay time but still a longer one than in the original sea horse built.
Do I have to change some of restistors again or can I only change the pot from 50K into let's say 10K?
I don't really know what the resistors are for in this mod.