Can You Run One Speaker Off Two Amplifiers: A Comprehensive Guide

Connecting speakers to amplifiers can sometimes be straightforward, but connecting multiple amplifiers to a single speaker is a bit more complex. This article delves into the possibilities and pitfalls of running a single speaker off two amplifiers, offering insights from experienced professionals and providing practical advice.

Understanding Amplifier Feedback and Configuration

Both amplifiers are designed with negative feedback between the output and input to minimize distortion. However, the challenge arises when you attempt to parallel these amplifiers. The feedback from one amplifier can affect the performance of the other, leading to potential issues like blown transistors. We’ll explore this in detail and discuss the consequences of this setup.

Parallel Connection Challenges

Parallel connections between two amplifiers can indeed lead to feedback distortion. Essentially, the negative feedback from one amplifier can interfere with the other, causing the feedback loop to become unbalanced and leading to the amplifiers' output transistors blowing.

One approach is to connect the speaker between the “hot” outputs of the two channels. In practice, this setup will deliver the difference between the two channels, which can result in unusual or undesirable sound for most source materials. However, this configuration won’t work with all amplifiers, particularly those that don’t have one side of the output grounded, such as many car amplifiers.

Understanding Equipment Capability

While some speakers are designed for multiple-amping, and some amplifiers have a bridge mode to combine their power, it is crucial to understand the exact capabilities of your equipment. Attempting to parallel two amplifiers without this knowledge can result in damage to your amplifiers or even fires. The user manual for your equipment is the ultimate guide and should be followed precisely.

Some examples of equipment that support multiple-amping are the Steinway Lyngdorf Model B speakers, which require four amplification channels with digital crossover done inside the stereo/surround processor. Similarly, amplifiers that offer a bridge mode can be used to combine their power.

Electro-acoustic Insights

Electronically, there is little advantage to running a speaker off two amplifiers. In fact, it could be potentially dangerous. Connecting two outputs together via a shared input can create a scenario where the low impedance of the output doesn’t match the higher impedance of the input, leading to unintended current sinking. This mismatch can cause the amplifier to trip and damage its power transistors.

For those who wish to distribute signal inputs, using a mixing panel to combine the signals before sending them to the power amplifier is a safer and more reliable method. Disconnecting the speaker from one amplifier and connecting it to another is a viable alternative, provided it is done correctly and not at the same time as the other amplifier is active.

Real-World Experiences and Lessons Learned

Mr. J., a seasoned professional, shares his personal experience: 'I tried to run a speaker off two amplifiers and it blew up one of the amplifiers in the process. It cost me 80 Dutch Guilders to fix. The problem lies in connecting two outputs together through a shared input. The low impedance of the incorrectly connected input meant it was sinking a significant amount of current unintentionally, causing the amplifier to physically pop its power transistors. The magic smoke escaped, literally! You are better off mixing the input signals with a mixing panel before sending them to the power amplifier.'

Another example: 'Tried to connect a speaker to two amplifiers. In the process of parallel connection, the output transistors of the amplifiers blew up, costing me a whopping 100 dollars for replacements. It was a costly lesson, indeed.'

Conclusion

While there are ways to use two amplifiers with a single speaker, it is important to approach this setup with caution. Understanding the limitations of your equipment and following the correct procedures can help you avoid potential damage. Whether you choose to use a mixing panel or disconnect the speaker from one amplifier, always prioritize safety and adherence to the user manual.