This page introduces systems theory using the classic example of a sound system. However, it goes beyond a simple explanation by exploring what limits amplifying feedback cycles.

Most people have experienced audio feedback: the sudden, piercing screech that occurs when a microphone picks up and re-amplifies its own sound. This escalating loop is an example of an amplifying feedback cycle, where something small becomes large, very fast.

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Website development

There are many planned links on this page. They are not active because the pages do not exist yet. I am currently writing them and plan to add about 15 pages to the site. 15 Nov 2025.

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I include this page on systems theory because this theory, and especially the concept of amplifying feedback cycles, helps explain many systems. Understanding the amplifying cycle that drives audio feedback can help us comprehend:

• The amplifying feedback cycles that drive human problems, and
• The danger of the multiple amplifying feedback cycles driving climate change.

For example, when audio feedback occurs, the sound system reaches its maximum power, amplification ceases, and the volume remains at a constant high level. Unchecked amplifying feedback is self-limiting, and it’s informative to consider the feedback cycles driving global warming in this light. Unchecked, the amplifying feedback cycle driving the melting of Arctic sea ice will only terminate when the last remaining sea ice has melted. At that time, with no ice remaining to reflect the sun’s heat back into outer space, the dark Arctic waters will be absorbing the sun’s heat at a high rate, and this heat would provide maximum support to the other global heating cycles.

Understanding how feedback works in a simple sound system provides a solid foundation for recognising how similar mechanisms operate in more complex systems.

*link to climate feedbacks

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Self-amplifying feedback in a sound system.

Audio feedback occurs when a “self-amplifying feedback cycle” becomes dominant in a sound system.

This cycle starts with:

• the microphone picking up a resonant pitch, which
• increases the amplifier output at this pitch, which tends to
• increase loudspeaker volume at this pitch, which tends to
• increase the input volume of this pitch to the microphone.

While this cycle dominates, “the louder it gets, the louder it gets”, but the amplification cannot go on forever.

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Feedback cycles show tendencies.

A feedback cycle indicates what tends to happen. Other factors can intervene and break the cycle. For example, “louder loudspeaker volume” only “tends” to produce “louder microphone input”. When someone puts a bag over the loudspeaker, you will get “softer microphone input”, not “louder microphone input”.

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The nature of any amplifying feedback cycle

Like the sound system amplifying feedback cycle, any amplifying feedback cycle has a circular sequence of causal connections between system attributes, in which an increase in any attribute of the cycle influences the following attribute and then the next, creating a ripple effect around the cycle until it increases itself, which causes a further ripple around the cycle (Capra, 1996, p. 56).

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Maruyama & his Second Cybernetics

Maruyama (1968) revolutionised systems theory by focusing on amplifying feedback cycles and their creative nature. He called his theory “the second cybernetics”, in contrast with earlier cybernetics, which focused on the destructive nature of amplifying feedback and mechanistic, damping feedback cycles. According to Maruyama:

• Amplifying feedback cycles are widespread (p. 304).
• Amplifying feedback cycles can disrupt the existing order and create a new order. For example, rock weathering is an amplifying feedback process that is (1) a vicious cycle in that it destroys rock, but also (2) a creative, virtuous cycle in that it creates fertile soil and forests (p. 305).
• These feedback cycles interact and can support or counterbalance one another, producing stability, oscillation, or transformation. (p. 312).
• Amplifying feedback cycles occur between people and can cause problems; for example, two aggressive individuals can easily escalate a misunderstanding into a physical fight.
• These cycles can also occur within a person and cause problems. For example, reduced self-confidence can lead to poor performance, which in turn can further reduce self-confidence (p. 312).
• In psychotherapy, the goal should be to break vicious, damaging feedback cycles underlying the presenting problem and to initiate virtuous feedback cycles that alleviate the presenting problem (p. 312).

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Capra: Feedback cycles reveal organisation.

Feedback cycles display the organisation of a system, as distinct from the system’s physical structure (Capra, 1997, p.63).

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Alternative names for feedback cycles

You can call an amplifying feedback loop a:

• Positive feedback,
• Deviation amplifying mutual causal process (Maruyama)
• Self-amplifying feedback loop,
• Self-reinforcing cycle,
• Vicious cycle, and
• Virtuous cycle

You can call a damping feedback loop a:

• Negative feedback,
• Balancing feedback,
• Stabilising feedback, and
• Deviation counteracting mutual causal process (Maruyama)

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Amplifying feedback & other influences

For the systems discussed here, I typically highlight a key amplifying feedback cycle that drives change or problem behaviour. Unfortunately, the amplifying cycle by itself suggests that amplification can continue indefinitely, which defies common sense. A more realistic understanding recognises that every amplifying cycle operates together with other influences—some that reinforce the cycle and others that inhibit it. Recognising these additional influences is essential for understanding the system.

The following table provides a brief overview of these influences; below the table, I discuss each influence in more detail.

*table

Influence	Inhibitors cause delays	Reinforcers
Other feedback cycles	A damping feedback cycle can control amplifying feedback and maintain system stability by opposing the deviation of a variable from its target value.   Feedback cycles can interact and set up oscillation.	Other amplifying feedback cycles can reinforce the considered amplifying cycle, forming a group of mutually reinforcing cycles.
The amplifying feedback cycle itself	A self-amplifying feedback is eventually self-limiting.   The amplification continues until it reaches a limit, such as exhausting a necessary resource, causing the cycle to terminate or pause.	An amplifying feedback is self-reinforcing.   Unimpeded, it transforms the system, destroying the old system and creating a new one.
External events	External events can disrupt an amplifying feedback cycle.	External events can strengthen an amplifying feedback cycle.

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Inhibiting amplifying feedback

First, consider the things that can inhibit an amplifying feedback cycle.

Inhibitor: A damping feedback cycle.

A damping feedback cycle can control an amplifying feedback cycle. The damping maintains the system’s integrity by reducing the deviation of one system variable from its target value.

Consider the damping feedback cycle that constrains the audio feedback amplifying cycle. It is the sound operator who hears the feedback escalating and adjusts the controls to damp the audio feedback. Here is a diagram of the damping feedback cycle.

More Deviation: Excessive Loudspeaker volume Less		More Control: The operator reduced power to the amplifier. More

*Diagram *Loudspeaker *damp

In this damping cycle:

• The upper arrows convey that more “excessive volume” tends to cause more “control”; and
• the lower arrows convey that more “control” tends to cause less “excessive volume”.

See my page on feedback diagram formats. *Link.

(You can think of gambling like this: a damping feedback cycle can limit excessive gambling, e.g., the gambler can decide that they have spent too much time or money on gambling and leave a gambling venue.)

The nature of any damping feedback cycle

In general, a damping feedback cycle has a circular sequence of causal connections, as does the sound system damping cycle shown above. The cycle differs from an amplifying feedback cycle because, in a damping cycle, a deviation of one system attribute, such as a boat’s deviation from its target course, triggers a corrective action that reduces that deviation. This is the opposite of amplifying feedback, in which an increase in one system attribute causes a further increase in that attribute.

Here is a diagram of the damping feedback cycle for a sailing boat.

More Deviation: The sailing boat heads to the right of the target direction. Less		More Control: The sailor pushes the tiller further to the right. More

Inhibitor: Other feedback cycles

Other feedback cycles can inhibit an amplifying feedback. For example, a large fox population will significantly inhibit the amplifying feedback cycle of rabbits breeding, while a small fox population inhibits it to a lesser extent. Three feedback cycles interact.

op table

More Rabbit Numbers More		More Rabbit Breeding More

In this rabbit breeding cycle: (1) more rabbits tend to produce (2) more rabbit breeding, which tends to produce (3) more rabbits.

The fox-breeding cycle has precisely the same form as the rabbit-breeding cycle:

More Fox Numbers More		More Fox Breeding More

Now, foxes prey on rabbits, as shown in the following cycle.

More Fox Numbers Less		Less Rabbit Numbers Less

In this cycle: (1) an increase in fox numbers tends to (2) decrease rabbit numbers, which tends to (3) decrease fox numbers, which tends to (4) increase rabbit numbers, which tends to (5) increase fox numbers.

(Each of these three predator-prey feedback cycles is reversible. I discuss this briefly below.)

More complex mathematical models of predator and prey populations predict that these populations tend to oscillate, and nature reflects this phenomenon. See the Wikipedia entry on the Lotka-Volterra equations.

Inhibitor: Reaching a maximum plateau

Any uncontrolled amplifying feedback cycle will eventually reach a limit because physical quantities, such as the power used by an amplifier or the volume emitted by a loudspeaker, have limits and cannot increase or decrease indefinitely.

One way an amplifying cycle can limit itself is by reaching an upper limit. This can occur in the sound system when the power required to produce a louder sound increases until it reaches the maximum power available, and the audio feedback volume plateaus at its maximum volume. Here is a diagram of this self-limiting feedback cycle.

“Microphone input volume” increases (1).		Electric power used for amplification increases (2).
	The increase in “speaker output volume” drops to zero as the “power used” approaches its maximum (3).

In this cycle, (1) an increase in the volume input to the microphone tends to (2) increase the electric power used to amplify the sound, which tends to (3) increase the speaker output volume, but:

• As the power used approaches its maximum, the amount of this increase reduces, and
• When the power used reaches its maximum, the increase in the speaker’s output volume becomes zero, and the screech reaches a constant high volume.

The audio feedback cycle and this self-limiting feedback cycle work together to organise the sound system. This self-limiting cycle reflects the diminishing return of amplification as the power approaches its maximum.

This cycle does not preserve the system; it transforms the system by driving the volume to its upper limit. The venue could not use a sound system with this potential; their audience would have to flee whenever the audio feedback cycle became dominant.

(You can think of gambling reaching an upper limit due to a system limit. For example, when a gambler is betting at the maximum rate that one poker machine can accept bets.)

Inhibitor: Breaking the system

An amplifying feedback cycle can limit itself by escalating until it exhausts a necessary resource or breaks the system, leading to zero activity.

In the sound system, the amplifying cycle can increase the volume of the screech until a component in the system fails, causing it to break, and leaving silence.

More Loadspeaker Volumes Zero when the stress becomes too great.		Less System Stress Less

*Diagram *Loudspeaker *yes *damp

In this cycle:

• The upper arrow shows that more “loudspeaker output volume” tends to cause more “system stress”; and
• The lower arrow shows that more “system stress”, when it becomes too much, leads to component failure and zero loudspeaker volume.

This cycle resembles a damping feedback cycle, but it is not one, as it does not control deviation away from a target.

(You can think of gambling in this way. When a person does not pause their gambling by themselves, an external limit can pause their gambling, such as (1) running out of cash, (2) ending up in gaol, and (3) the gambling venue closes and ends a marathon gambling period.

Another example is with a global heating feedback cycle that melts Arctic sea ice. This cycle will stop when there is no ice left to melt.

Inhibitor: External events

External events can disrupt an amplifying feedback cycle.

For the audio feedback, an electricity supply failure would disrupt the cycle, although if the audio feedback continued, it is more likely that the operator would pull the plug.

For a gambler, many external events can interrupt their gambling, e.g., a hospital stay.

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Reinforcement of amplifying feedback cycles

Reinforcement: an amplifying feedback reinforces itself

An amplifying feedback is self-reinforcing. Unimpeded, it transforms its system, destroying the old system and creating a new one.

The audio feedback, if unimpeded, could hit a continuous maximum volume or break the sound system. Both these possibilities are transformations that would leave the event without a usable sound system.

Reinforcement: a group of amplifying feedback cycles

Other amplifying feedback cycles can reinforce the considered amplifying cycle, forming a group of mutually reinforcing cycles.

This occurs in the amplification of problem gambling and global heating, but not in the simpler sound system.

*Link to both the gambling and heating pages.

Reinforcement: External events

External events can reinforce an amplifying feedback cycle.

For audio feedback, this reinforcement is not likely. However, for other systems, such as global heating, this is the critical issue. The human burning of fossil fuels, an external influence on the natural climate system, has triggered global warming and poses a risk to life as we know it on planet Earth.

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Other features of amplifying feedback  

Here are some other features of amplifying feedback cycles that I will consider. An amplifying feedback cycle can:

• Produce exponential change when it meets no resistance.
• Experience time delays.
• Reverse directions

Let’s examine these points in more detail.

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Amplifying feedback & exponential change

Once an amplifying feedback cycle becomes dominant and stays so, it will bring exponential change, initially slow and then explosive, until the transformation it initiates reaches a limit and the cycle can go no further.

For example, when a person in a chair leans back past the tipping point, they rotate until they reach the limit of rotation — the floor. The rotational energy does not increase at a constant rate over time. It increases exponentially.

Refer to the “Tipping Point” page on this website.

Tipping points & feedback loops

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Time delays

This exponential escalation often does not continue unabated due to the inhibitors of amplifying feedback. These inhibitors include the discussed damping feedback, interaction with other amplifying feedback cycles, reaching limits, and external events. This means that amplifying feedback can often not gather pace. Additionally, some processes are inherently slow, such as melting ice, which requires a large amount of energy.

Sound system design ensures there is minimal delay in the amplification so that hearing the performer seems natural. This immediate amplification means that the feedback screech can escalate to an unbearable level within seconds.

The delays occur in other systems:

• For a gambler, life events, such as a hospital admission, can delay an amplifying feedback cycle that drives their problem gambling.
• In global heating, a volcanic eruption could temporarily delay the amplifying heating cycles.

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Reversibility

Some amplifying feedback cycles are reversible as they can amplify changes in either direction. For example, the previously discussed interaction between fox and rabbit numbers is reversible.

More Fox Numbers Less		Less Rabbit NUmbers Less

In this cycle: (1) an increase in fox numbers tends to (2) decrease rabbit numbers, which tends to (3) decrease fox numbers.

The reverse is also true:

Less Fox Numbers More		More Rabbit NUmbers More

In this cycle: (1) decrease fox numbers tends to (2) increase rabbit numbers, which tends to (3) increase fox numbers.

Another example is the current amplification of global heating and the melting of Arctic sea ice. This is currently amplifying global heating, but if cooling were to occur, it could also amplify global cooling.

*Link.

The amplifying feedback cycle driving the screech of feedback is not reversible. If a person put their hand over the microphone, causing the volume of the input to the microphone to drop, the cycle would continue to increase the volume.

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A self-organising system

Systems that receive a continual input of energy can become self-organising. For example, the sun provides the energy that drives the water cycle with its evaporation, rainfall, and river flow. This energy shapes the character of rivers as people know them, creating the recurring rapids and eddies that consistently appear depending on the water levels (Capra, 1996).

Although I will not elaborate on this here, I propose that people’s chosen actions function in a similar manner. Each chosen action tends to (1) strengthen the ideas and feelings that motivated it, while (2) weakening those associated with the rejected alternative actions. The feedback cycles that organise these chosen actions, feelings, and ideas form a self-organising process that continually shapes a person’s character.

*link to my Weinberg page

Conclusion

First, I found amplifying feedback cycles useful for understanding and assisting my counselling clients. The cycles help understand what drives a problem. Then I realised that other amplifying cycles were driving global heating and more. Systems theory applies to any system. This framework helps me understand the world, including human problem development and recovery.

A more detailed examination of feedback cycle interactions could draw on insights from system dynamics, chaos theory, population dynamics, catastrophe theory, and mathematics. Nevertheless, here again are several ways in which feedback cycles can interact.

Influence	Inhibitors cause delays	Reinforcers
Other feedback cycles	A damping feedback cycle can control amplifying feedback.   Feedback cycles can interact and set up oscillation.	Other amplifying feedback cycles can reinforce the considered amplifying cycle, forming a group of mutually reinforcing cycles.
The amplifying feedback cycle itself	A self-amplifying feedback is eventually self-limiting when the amplification reaches a limit and pauses.	An amplifying feedback is self-reinforcing and can transform its system.
External events	External events can disrupt an amplifying feedback cycle.	External events can strengthen an amplifying feedback cycle.

Amplifying feedback cycles do not exist in isolation; various inhibiting factors can slow or delay the exponential changes they might otherwise produce. Recognising these influences enhances the credibility of systems theory and deepens understanding of amplifying feedback. In turn, this reinforces the argument that such cycles are key drivers of both climate change and human problems.

All the above influences are at work in the life of a problem gambler.

*Link.

How to present feedback cycles

See my page on how to present feedback cycle diagrams.

*link.

Related pages

*Link.

System theory pages

Counselling pages

The amplifying feedback cycles pages

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Updated: 15 Nov 2025