Quadrant Modulator feeds its fully wet output back into the multiplier, with inverted and non-inverted feedback available around a center-off control. The returning signal is not simply made louder. It goes through the multiplication stage again.
One pass through a ring modulator creates a new spectrum from the source and carrier. Send part of the wet result back to the input, and the next pass starts with audio that already contains sidebands. Repetition is the point.
The wet feedback path inside a Quadrant Modulator therefore behaves differently from feedback around a plain gain stage. Each trip through the loop gives the carrier another chance to reshape material created on the previous trip, so modest feedback can alter spectral structure before it sounds obviously louder.
The second pass does not merely repeat the first pass. Mathematically, the returned wet signal is multiplied by the carrier again, so part of the result behaves like the source multiplied by the carrier squared. For a sine carrier, squaring the waveform produces a constant component plus energy at twice the carrier frequency.
A useful consequence falls out of that arithmetic. The second traversal can put some energy back at the source frequencies while also creating another family of components displaced by twice the carrier frequency. Later traversals involve higher powers of the carrier and can introduce relationships tied to three times, four times, and further multiples of its frequency.
Real program material makes the growth less tidy because the source already contains many partials. A drum loop or distorted synth can seed dozens of components into the first pass, then feedback sends the newly generated mixture around again. You hear a widening metallic cloud rather than a simple pair of textbook sidebands.
Historical circuit work even includes feedback around a ring-modulator bridge as part of the modulator architecture. Modern audio implementations can arrange the loop differently, but the underlying lesson survives. Returning modulated output to a multiplication stage creates a different system from placing distortion or EQ after a one-pass ring modulator.
Non-inverted feedback lets successive contributions enter with one sign convention. Inverted feedback alternates the sign of returned contributions, which can strengthen some instantaneous relationships while reducing others once the paths are summed and multiplied again. Frequency content may be similar on paper while the waveform, peaks, and apparent tone change noticeably.
Carrier phase complicates the result further. A component that returns one sample, several samples, or a processing block later no longer meets the oscillator at exactly the same phase position. Small internal delays therefore affect which repeated components reinforce and which partly cancel, particularly as the carrier frequency rises.
This is why feedback polarity is more useful as a timbre control than a simple bright-versus-dark switch. Try equal amounts on either side of zero and the difference can be obvious even before the spectrum looks dramatically different. Percussive material tends to reveal the altered peak structure quickly.
Any feedback system also has a stability problem to respect. If a loop returns enough energy with favorable phase, small signals can grow instead of decay. Ring-modulation and frequency-shifting hardware can be patched into self-oscillation under suitable feedback conditions, although the exact threshold depends on the implementation, gain structure, delay, filtering, and nonlinear stages.
Quadrant Modulator places its tube-style limiter after the dry and wet blend, while the documented feedback path returns the fully wet modulated signal to the input. The limiter can color or restrain the final output, but its position means you should not treat the output meter as a perfect picture of what is happening inside the feedback loop.
Start with feedback near zero and a sparse carrier waveform. Increase the return until the second and later spectral generations become audible, then compare the inverted side at roughly the same amount. Dense chords need less encouragement because they give every pass more partials to multiply, while a single sine or simple bass note lets you hear the recursive structure with far less camouflage.
One pass through a ring modulator creates a new spectrum from the source and carrier. Send part of the wet result back to the input, and the next pass starts with audio that already contains sidebands. Repetition is the point.
The wet feedback path inside a Quadrant Modulator therefore behaves differently from feedback around a plain gain stage. Each trip through the loop gives the carrier another chance to reshape material created on the previous trip, so modest feedback can alter spectral structure before it sounds obviously louder.
A ring modulator feedback loop multiplies the spectrum again
Take a clean source multiplied by a sine carrier. The first pass shifts each source component into an upper and lower sideband around the carrier relationship. Feed some of that result back, and the multiplier sees those sidebands as fresh input.The second pass does not merely repeat the first pass. Mathematically, the returned wet signal is multiplied by the carrier again, so part of the result behaves like the source multiplied by the carrier squared. For a sine carrier, squaring the waveform produces a constant component plus energy at twice the carrier frequency.
A useful consequence falls out of that arithmetic. The second traversal can put some energy back at the source frequencies while also creating another family of components displaced by twice the carrier frequency. Later traversals involve higher powers of the carrier and can introduce relationships tied to three times, four times, and further multiples of its frequency.
Real program material makes the growth less tidy because the source already contains many partials. A drum loop or distorted synth can seed dozens of components into the first pass, then feedback sends the newly generated mixture around again. You hear a widening metallic cloud rather than a simple pair of textbook sidebands.
Historical circuit work even includes feedback around a ring-modulator bridge as part of the modulator architecture. Modern audio implementations can arrange the loop differently, but the underlying lesson survives. Returning modulated output to a multiplication stage creates a different system from placing distortion or EQ after a one-pass ring modulator.
Inverted feedback changes how repeated orders combine
Flipping the feedback polarity does not create a new set of frequencies by itself. An inverted signal contains the same magnitude spectrum as its non-inverted version, with its polarity reversed. The audible difference appears when returned material combines with the current input and with products from earlier trips through the loop.Non-inverted feedback lets successive contributions enter with one sign convention. Inverted feedback alternates the sign of returned contributions, which can strengthen some instantaneous relationships while reducing others once the paths are summed and multiplied again. Frequency content may be similar on paper while the waveform, peaks, and apparent tone change noticeably.
Carrier phase complicates the result further. A component that returns one sample, several samples, or a processing block later no longer meets the oscillator at exactly the same phase position. Small internal delays therefore affect which repeated components reinforce and which partly cancel, particularly as the carrier frequency rises.
This is why feedback polarity is more useful as a timbre control than a simple bright-versus-dark switch. Try equal amounts on either side of zero and the difference can be obvious even before the spectrum looks dramatically different. Percussive material tends to reveal the altered peak structure quickly.
Loop gain turns texture into instability
Feedback level decides how much of each generation survives into the next one. At low settings, later passes fall away quickly and you mainly hear extra density around the first modulation products. Raise the return level and higher-order products stay strong enough to become part of the sound rather than residue behind it.Any feedback system also has a stability problem to respect. If a loop returns enough energy with favorable phase, small signals can grow instead of decay. Ring-modulation and frequency-shifting hardware can be patched into self-oscillation under suitable feedback conditions, although the exact threshold depends on the implementation, gain structure, delay, filtering, and nonlinear stages.
Quadrant Modulator places its tube-style limiter after the dry and wet blend, while the documented feedback path returns the fully wet modulated signal to the input. The limiter can color or restrain the final output, but its position means you should not treat the output meter as a perfect picture of what is happening inside the feedback loop.
Start with feedback near zero and a sparse carrier waveform. Increase the return until the second and later spectral generations become audible, then compare the inverted side at roughly the same amount. Dense chords need less encouragement because they give every pass more partials to multiply, while a single sine or simple bass note lets you hear the recursive structure with far less camouflage.
