Connecting your audio system for the first time often presents a maze of colored ports on the back of your receiver. While the labeled outputs for speakers are straightforward, the lower row of connections can seem intimidating. The pre out on receiver section is specifically designed for this purpose, acting as a direct link to your power amplifier or active speakers to bypass the internal amplifier circuitry.
Utilizing these outputs is the standard method for audiophiles and home theater enthusiasts who want superior sound quality. The internal amps in most receivers are often basic, designed to handle general consumer needs rather than high-fidelity audio reproduction. By using the pre out on receiver, you delegate the critical amplification process to a separate, dedicated unit that can drive your drivers with more current and cleaner power, resulting in a noticeably richer and more dynamic soundstage.
Understanding Preamp Outputs
To effectively connect your gear, you must first understand what a preamp output actually is. Unlike speaker-level outputs that carry a amplified signal, the pre out on receiver carries a line-level signal. This is the same type of signal that comes from the CD player or the TV's audio out, but it originates directly from the receiver's own internal processing section. This signal contains all the audio information and volume control data, but it requires an external power amplifier to convert it into sound through your passive speakers.
Think of the receiver as the brain of the system and the external amplifier as the muscle. The pre out on receiver sends the raw audio instructions to the amp, telling it what to play and at what volume. This separation of duties reduces electrical interference and allows the amplifier to focus solely on producing a clean, robust signal to your speakers without the interference of digital processing or radio frequency noise that often plagues internal amps.
Connecting to an External Power Amplifier
The most common scenario for using the pre out on receiver is bridging the gap between a modern AV receiver and an older or high-performance power amplifier. This is a cost-effective way to upgrade your system without replacing your entire receiver. You keep the receiver for its surround sound processing, tuner, and streaming capabilities, while leveraging the superior amplification of a separate unit.
To execute this connection, you will need a pair of RCA cables. Plug one end of the cable firmly into the pre out left and right (or stereo pre out) ports on the back of your receiver. Connect the other end to the corresponding left and right line in or auxiliary inputs on the back of your power amplifier. Once connected, you will need to change the input source on your power amplifier to "Line In" or "Aux" to match the cables.
Setting the Receiver ConfigurationSimply wiring the cables is not enough; the receiver needs to know that it is not powering the speakers itself. You must navigate the receiver's on-screen menu to disable its internal amplification for the connected speakers. Look for settings typically labeled as "Speaker Configuration," "Audio Setup," or "Output Mode."
In this menu, you will usually find an option for "Speaker Size" or "Load." Set the main speakers to "Small" if you are using a subwoofer, but more importantly, find the setting for "Internal Amplifier" or "Pure Direct Mode." Select the option to turn off the internal amps for the main channels. The receiver will now treat its main outputs as pre out channels, sending the line-level signal exclusively to your external amplifier.
Alternative Uses: Bi-Amping and Active Crossovers
The versatility of the pre out on receiver extends beyond just connecting a single power amp. If your receiver features multiple pre out pairs, you can engage in "Bi-Amping." This involves using two separate amplifiers, one for the high-frequency (tweeter) wires and one for the low-frequency (woofer) wires of your speakers. This requires speakers with bi-wire or bi-amp terminals and can result in significantly improved clarity and separation.
Additionally, you can utilize the subwoofer pre out. Most receivers feature a dedicated LFE output designed specifically for subwoofers. If your receiver lacks a dedicated sub out or if you own an active subwoofer with line inputs, you can use the main pre out with an RCA splitter cable to send the low-frequency effects signal to both your external amp and your subwoofer simultaneously.
Troubleshooting Common Issues
Even with the correct wiring, users sometimes encounter issues when relying on the pre out on receiver. The most frequent problem is a lack of sound. If this occurs, double-check that the receiver’s internal amplifier setting has been turned off for the main zone. If the setting is correct but there is still no sound, ensure the volume knob on your external power amplifier is turned up and that the amplifier itself is powered on.
Another issue is ground hum or a buzzing sound. This usually indicates a ground loop, where multiple devices are plugged into different power outlets creating a circuit. To resolve this, try using a ground loop isolator on the cable connecting the receiver to the amplifier, or invest in a power conditioner to standardize the electrical signal. Ensuring all power sockets are tied to the same circuit in your home wiring can also eliminate this interference.
