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SKU: 76814778615

Subdecay Octave Theory - Octave Modulator/Synthesizer

Sale price$179.10 Regular price$199.00
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Description

Subdecay Octave Theory - Octave Modulator/SynthesizerThey say: Octave shifting guitar synth. World's first octave modulator octave shift pedal. World's first shepard tone guitar synthesizer. LFO and envelope octave shifting. All analog filter design. Inspired by old school synthesizers and the 8 bit computing era. The first ever guitar synth with octave modulation So what the heck is octave modulation? The octave theory seamlessly crossfades between octaves. Paired with an awesome filter this creates a

They say:

  • Octave shifting guitar synth.
  • World's first octave modulator / octave shift pedal.
  • World's first shepard tone guitar synthesizer.
  • LFO and envelope octave shifting.
  • All-analog filter design.
  • Inspired by old-school synthesizers and the 8-bit computing era.

The first ever guitar synth with octave modulation

So what the heck is octave modulation? The octave theory seamlessly crossfades between octaves. Paired with an awesome filter this creates a multitude of possibilities. like 8 bit chiptune sounds, classic guitar synth, super sub bass tones and the world’s first ever shepard tone guitar synthesizer.

With great power…

An array of knobs covered many early 1980s synthesizers. This gave you the power to create a wide range of sounds. Of course, on some settings the synthesizer wouldn’t make a sound, would go into uncontrollable oscillation, or make weird noises. Sometimes the weird noises weren’t the weird noises you expected.

While many guitarists enjoy tweaking and honing their tone most of us don’t have that level of patience for fiddling with a matrix of interactive settings. The Octave Theory strikes the perfect balance giving you the power to create your own sound without endless knob tweaking or (gasp!) a tedious menu driven interface.

The Filter:

Resonant filter inspired by the Korg MS20. Like the MS20 the resonance knob can push the Octave Theory into oscillation. Most guitar synth pedals won’t let you go there. They think you can’t handle so much raw power. To be fair many of those filter oscillation sounds can get shrill or overbearing. If you keep the filter frequency low you can give your synth tones some growl. Use this power responsibly. 

AMP vs. Filter priority and envelopes.

ADSR envelopes are a mainstay of synthesizers. While lacking full external ADSR control an internal ADR (Attack/Decay/Release) envelope is generated to control the oscillator output level. (AMP – synthspeak for modulating the oscillator output level.)

AMP Priority (white marker): In modes with the white marker the decay knob gives you full control of the AMP decay. In these modes the filter also follows the ADR envelope at a fixed depth. This allows you to make notes decay quickly and gracefully. Turning the knob up allows for longer decay times.

Filter Priority (green marker): In green marker modes the filter follows an envelope generated by the strength of the input. (The same way envelope filters work) The depth knob controls how much influence the the input envelope has over the filter. When in filter priority the internal ADR envelope is fixed with infinite decay time.

Octave Modulation:

Modulate your octaves in four ways. LFO modulation, envelope modulation, shepard tone, or manual mode.

LFO: This is where you’ll find the chiptune sounds, especially with the square and double square wave modes.
In the triangle, square and double square modes the filter follows the internal ADR and the freq knob. In random Mode the filter follows the LFO. The octave mod knob controls the LFO speed.

Envelope: Playing dynamics modulate the octave cross fade.  The octave mod knob controls the envelope’s overall influence. 

Shepard Tone:  As you work your way up the guitar neck playing higher notes, the octave cross fade descends. When set = modes playing one octave higher will produce the same note. You can play up the neck forever and arrive at the same pitch whether you are playing an open low E or the high E string on the twelfth fret. In  modes the output pitch will get lower and lower as you play higher up the neck. In all shepard tone modes the oct. mod knob manually controls the octaves from several octaves down to several octaves up.

Manual mode: This is most similar to our original guitar synth pedal, the Octasynth, but with the most requested feature added. Instead of the Octasynth’s blend control which only allowed for one or two octaves down, the oct. mod knob takes you from three octaves down to two octaves up.

Shipping Notes
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Exchange/Return Notes
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SKU: 76814778615

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Ashley
Lake Worth, US
★★★★★ 4
Woke Up Glowing ✨ (But Sleeping In It Is a Stretch lol)
Scent: Collagen, Size: 4 Count (Pack of 1)
I was honestly impressed with this mask! It feels super soft, cooling, and refreshing while wearing it. The jelly texture makes it feel really hydrating and luxe, like a mini spa night at home. My skin looked smooth, plump, and GLOWING the entire next day after I took it off. Like… noticeably radiant. I also have sensitive skin, so I was a little nervous trying it at first, but I didn’t have any irritation or reaction at all. My skin felt calm, hydrated, and refreshed afterward. One thing I actually liked was that the mask was easy to customize a little. I have a nose piercing, so I just tore a small piece near my nose so it would fit comfortably without irritating it. The material held up perfectly, so that was a nice bonus for anyone with piercings or who just needs a better fit in certain areas. My only complaint is the “sleep in it” part of the instructions. I personally don’t see how that’s possible 😅 The mask stays pretty moist and jelly-like the whole time, so it felt uncomfortable to lay down in and I kept feeling like it would slide around. I ended up just wearing it for a while before bed instead. Overall though, the results were worth it and I’d definitely use it again for the glow alone!
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Reviewed in the United States on May 3, 2026
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Anna
Battle Creek, US
★★★★★ 5
Nice mask! Caviar
Scent: PDRN, Size: 4 Count (Pack of 1), Scent: PDRN, Size: 4 Count (Pack of 1)
The first 3 pictures were taken after the first hour and a half. The second 3 pictures were taken at 2 hours. The mask had a hard time dissolving underneath my eyes and around my chin area mostly but everywhere else it hardened within the first hour or so. I will try to wear it for longer than 2 hours next time. To see if that changes, but my skin feels really nice right now. It's a little sticky, but it looks healthy and has a nice glow. Application is easy. I love that its separated into 2 parts. Doesn't fit well around the nose between the eyes and doesn't cover my entire face but its a great mask. I tried the caviar one this time. I have the collagen ones as well but these have better reviews. They seem to work effectively, for a nice glow and self pamper session.
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Reviewed in the United States on May 5, 2026
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Mom who does everything
West Palm Beach, US
★★★★★ 5
My Favorite Mask
Scent: Collagen, Size: 4 Count (Pack of 1)
I’ve been really impressed with this Bio-Collagen hydrogel mask! It feels incredibly cooling and soothing on the skin, especially after a long day. The overnight wear is a huge plus—you wake up with your skin feeling noticeably more hydrated, plump, and smooth. It doesn’t feel heavy or sticky, and it stays in place better than most sheet masks. After a few uses, I’ve noticed my skin looks more refreshed and even, and my pores appear a bit more minimized. It’s a great option when your skin needs a little extra boost or before an event when you want that “glow.”
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Reviewed in the United States on May 5, 2026
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Firethorn
Lowell, US
★★★★★ 5
Love ❤️ this product! 100% recommend!
Scent: Collagen, Size: 16 Count (Pack of 1)
My initial encounter with these was until TikTok but I ordered them from Amazon for myself and my daughter for convenience and Prime shipping. There were two choices I think the one is a four-pack and the one I got is a 16 pack. The 16 pack will last you 4 months if you're doing it once a week as instructed. I open the top and two sides when I'm doing it just to have accessibility and to be able to use the remnants liquid in the pack after I'm done applying the facial part I put the liquid in the pack on my neck and chest. They are a little slippery when you take them out. I watched a video on how to apply it and did the bottom part first and then the top part sometimes I have to snip the top part near the nose to get it to fit properly but you don't have to in general. There are three pieces that are left over the two eye pieces and the lip piece. You can put them below your eyes or above your eyes on your brows and then put the mask over them which is what I do. Or you can put them under your eyes and put the mask over them but I find it doesn't absorb all the way in that location due to the double thickness I guess. The lip one you can put over your lip or put it on vertically over your throat where the skin can get a little saggy. Once you have it on it's best to sit back and relax for 30 minutes or so at about a 45° angle so it doesn't slip off. After about 10 to 15 minutes it doesn't slip around as much and after 30 it's obviously started absorbing and tends to stay pretty well. I haven't noticed any staining on the pillows or anything like that from it and by morning actually by 4 hours later it's completely absorbed and all you have left on your faces the plastic that it was attached to. You just pull that off and throw it away. It's white when you put it on and it's clear when it absorbs. I definitely noticed an improvement in my skin quality and the collagen sinks in easily and less about a week. I am a redhead with delicate skin and I haven't had any reaction to this product at all I know that other masks have caused problems for friends but I've used this one for over a year now and I love it. My daughter and I both use it weekly and they're easy to take with you if you're traveling great way to pamper your skin after a day outside on the beach. The price is reasonable for what it is and what it does. I've gotten several compliments on my skin and I'm over 60 so that saying something for the results! All in all this is a very good product, it doesn't smell and doesn't seem to have any impurities like some others. My skin isn't irritated by it and looks great afterwards. If you're wondering if it washes off once it's soaked in you can wash your face all you want but you're just going to have beautiful glowing cheeks. I wouldn't hesitate to recommend this or give it as a gift!
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Reviewed in the United States on June 11, 2025
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Kevin
Dallas, US
★★★★★ 5
Strong but Effective—Great Results if You Don’t Overdo It (Your Skin Will Warn You 😅)
Size: 8.11 Fl Oz (Pack of 1)
I’ve been using this glycolic acid toner for a few weeks now, and I have to say—my skin and I are finally on better terms. I originally bought it to deal with uneven texture and those random little bumps that seem to show up uninvited, and it’s actually made a noticeable difference. Within the first week, my skin felt smoother, and after a few weeks, I started seeing improvements in tone and dark spots. The quality is pretty impressive. It has a lightweight, watery texture that absorbs quickly and doesn’t feel heavy or sticky. There’s a slight tingling sensation at first, which can be a little surprising—but nothing too crazy. Think of it as your skin saying, “Okay, something is definitely happening here.” That said, this stuff is strong. I made the mistake of using it too often at first and my skin basically said, “Absolutely not.” Lesson learned—use it a few times a week, not every day (unless you enjoy living dangerously). Also, sunscreen is non-negotiable unless you want to undo all your progress. One thing I really like is the versatility—you can use it on other areas like underarms or back, which is a nice bonus. And when it comes to value for the money, it’s honestly great. The bottle is pretty big, and since you don’t need much per use, it lasts a long time. Overall, I’d say this is a high-quality product that actually delivers results—as long as you respect it. Treat it right, and it’ll treat your skin right… ignore the instructions, and it will humble you real quick.
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Reviewed in the United States on April 27, 2026

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