SVDS / SoloDallas Storm

[Chuck D. Bones]

These two women are out on the golf course. One of them tees up the ball and promptly shanks it into a foursome. One of the guys is hit. He groans and doubles over in pain, clutching both hands below the waist. The two women run over, all apologetic. The one who hit the ball approaches the injured man and tells him "I've very sorry I hurt you. I'm a physical therapist, and if you would allow me, I think I could relieve your pain."
The man reluctantly agrees, so the woman carefully loosens his belt and slides her hand inside his shorts. She gently massages him for several minutes and then asks "Now doesn't that feel better?"
The man replies "That was great, but my thumb is still killing me."

 

[beachbum]

This is a clone of the SoloDallas Storm, same as the Closed Circuit Booster Limiter. I built the Aion Gale because the PedalPCB board was not yet available at the time. Nice tone, subtle limiter, plenty of clean boost available and the 386 can drive a mile of cable. Read the Aion build docs about the origins of the SoloDallas Storm, pretty interesting! The Aion board contains two optional capacitors, both of which I ended up installing. One is a 120pF cap at the input to filter out RF interference. Most pedals have that, so including it was a no-brainer. The 2nd cap is a 10uF in parallel with the opto's LED. I started out with this cap omitted. Notes at the bottom end of the scale had some distortion at higher limiter settings. Bench testing confirmed that the opto's response time was fast enough for the LED ripple to modulate the LDR's resistance at low frequencies. Some optos are slow enough that this is not a problem. I installed the 10uF cap and the distortion was gone. The limiter's attack is still plenty fast. I socketed the 4558D with the idea that I might try swapping opamps. I was plenty satisfied with the sound, so I left well enough alone.

I built one of these recently and curious if yours exhibits similar behaviour. Hi pregain and playing with the threshold yields your standard compressor squish. What I found interesting is actually how the output volume behaves when pushed, especially with the pregain and threshold turned down below 10-11 o'clock. Instead of just getting a clean boost, I'm actually getting a fairly healthy amount of saturation and clipping and it sounds pretty nice going through a super clean signal chain to add a bit of "chucka" to your attacks.

 

[Chuck D. Bones]

I just put mine on the bench. With PREGAIN & VOLUME dimed and THRESHOLD at zero, the maximum undistorted output is 7.25Vp-p with 280mVp-p input. The measured gain is 28dB, which is what I'd expect with no compression (THRESHOLD at zero).

Next I tried your settings: PREGAIN & THRESHOLD at about 11. I could drive the input up to 1Vp-p (that's as high as my sig gen setup goes) with no distortion and 2.5Vp-p output.

I'm not observing the saturation you're describing, however that much output will overdrive most amps or pedals, so maybe the distortion is coming from outside the Gale?

Do you have C5 installed?

What do you mean by "pushed?"

 

[beachbum]

I'll try to record a clip, but I tested it straight into my interface, maybe going through the bigsky cabfilter.

pushed, just meant when you raise the volume past unity gain.

c5 and c1 were are not installed.

 

[Chuck D. Bones]

Follow-up:
I ended up removing C5, the optional smoothing cap in parallel with the opto's LED.

 

[music6000]

Follow-up:
I ended up removing C5, the optional smoothing cap in parallel with the opto's LED.

Why Chuck, Why?

 

[Chuck D. Bones]

I wanted to restore the slight low-freq grind that the SVDS exhibits. I can dial it in and out with the PREGAIN & THRESHOLD controls.

 

[jeffwhitfield]

Nice build, Chuck!

I built one of these some time ago. It's a good pedal...but really only good for a specific use. It's more of a tone sweetener to me. It's got some boost capabilities and the limiter is...err...somewhat limiting (kind of subtle). Really great circuit and perfect for the player looking to get the sound that this pedal helps with. However, I got a Source Audio ZIO shortly after and it ended up kicking this one off the board. I get more mileage out of my Source Audio ZIO and Atlas combo.

 

[music6000]

I wanted to restore the slight low-freq grind that the SVDS exhibits. I can dial it in and out with the PREGAIN & THRESHOLD controls.

Would increasing the limiter pot to A250K make it Squish more????

 

[MichaelW]

I have this on my bench for this weekend. Confused now about the "optionals". Put em in? Leave them out?

 

[Chuck D. Bones]

The 120pF cap at the input will sound the same in or out. I recommend it to guard against radio interference. If you don't have 120pF, 100pF will do.

I'd suggest leaving the smoothing cap out, play it and see if you hear any slight distortion when playing open chords. Depending on the speed of your opto / LDR, that cap may be totally unnecessary. Or you may like the tone.

 

[Chuck D. Bones]

Would increasing the limiter pot to A250K make it Squish more????

No, and in fact it may do just the opposite. Once IC1.2 saturates, you're not going get any more gain reduction. If you want more compression, you can increase R3 or better yet, build a different compressor. This circuit was tuned to have a specific tone and (I can't believe I'm saying this) modding it is probably not the best option. The Hollis Flatline (Madbean Four-One) compressor uses a similar architecture and has more sustain.

I like this one because the limiter is subtle. I have other compressor pedals for when I want huge sustain.