Playing a synthesizer through an amplifier and speaker gives you that rumble that only air being moved can generate. But what if the only amp and speaker you have around is a guitar amp?
Can you play a synthesizer or keyboard through a guitar amp? A synthesizer can plug directly into a guitar amplifier with a simple 1/4″ TS cable. However, synths output line level signals (higher amplitude and lower impedance than instrument level signals). Care must be taken not to keep the synth output low to avoid blowing guitar amps and speakers.
In this article, we'll discuss how to plug a synthesizer into an amplifier, the benefits of doing so, and the potential risks involved. We'll also consider a few top guitar amplifier options for reproducing audio from synthesizers.
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How To Connect Your Synth To A Guitar Amp
Let's get started from the very beginning: connections. How do you plug a synthesizer into a guitar amp?
Most synthesizers have line-level outputs labelled on the back. If you have one of them that says “Output (Mono),” that is exactly what you need to plug your cable.
Synthesizers that don't have such output should have a 1/8″ headphone jack. With a simple adaptor that can take the 1/4″ into a 1/8″, you can go from the synth to the amp as well.
The other end of the cable will go into the input of the amplifier. If it is a combo amp, all you need to do is power it on and start playing. If it is a head and cabinet configuration, you'll need to connect the head to the cabinet before starting to play.
It's important to note that guitar amp inputs expect instrument level signals from a guitar. Line level signals have greater amplitude/voltage and lower impedance. Headphone level signals also tend to have great amplitudes/voltages but have even lower impedance.
These mismatches don't necessarily mean that the connection will be bad. The high input impedance of the guitar amp will work well as the load for synth line or headphone outputs/sources. However, the synth output volume should be monitored and kept low to avoid overloading the guitar amp's preamp.
Benefits Of Playing A Synthesizer Through A Guitar Amp
Let's take a look at the positive aspects of plugging a synthesizer into a guitar amp:
Gain stages: one of the main characteristics of guitar tone is that overdrive is a welcomed phenomenon. While other instruments tend to stay away from distortion, guitar players love breakup tones. Thus, in the case you are after the 60s or 70s overdriven sound, you'll be getting what you need when cranking up a guitar amp.
Tone shaping: with guitar amp equalizers, we can tweak the tone of the synthesizer sound, further subtracting or adding frequencies depending on our needs. Of course, most synths will also have an EQ section as well. Guitar amps tend to have a limited frequency response (often only as low as 70 Hz and as high as 6,000 Hz), which will further shape the synth sound in ways that may yield interesting results.
Built-in effects: some modern amplifiers add a range of digital effects to the usual reverb, chorus, and tremolo. With them, you can create unique sounds that can push your sonic boundaries further than you imagined.
A Word Of Warning
Besides the plethora of benefits given above, there is a word of warning before you start experimenting: beware of the level and the low frequencies.
Remember our quick discussion on the various signal levels? Guitar amplifiers are made to amplify very low-gain signals coming from electric guitars. Synthesizers will typically connect to a guitar amp via line or headphone outputs, which typically output stronger signals.
Fortunately, most synths have a volume knob that doubles as an output signal level control. Try keeping it low to avoid blowing fuses and internal components at the guitar amp's preamp stage.
In the same vein, guitar amp speakers are designed and manufactured to withstand frequencies as low as 70Hz. This is because guitars are instruments rich in mid frequencies but without a massive low end not to step on bass guitar territory. Some synthesizer patches can go as low as 20Hz, potentially breaking the speaker's cone as it pushes too hard to reproduce frequencies it is not designed for.
So, keep the volume low and stay away from bass-rich, low-frequency patches.
Solid-State Or Tube/Valve Amp?
This is a question that players have been asking since solid-state amplifiers have become a regular option around the world. Let's see some pros and cons of each approach.
Synthesizers and solid-state guitar amps: solid-state guitar amplifiers tend to be the cleanest-sounding amps available in the market besides being more portable, lighter, and tougher than valve amps. Moreover, if they are Class-D, they feature a digital output amplifier, meaning they are even lighter. To some people's ears, their transparent sound lacks character and sounds sterile and stale.
Synthesizers and tube/valve guitar amps: Valve amps tend to have a richer, warmer sound than their solid-state counterparts. Also, they tend to overdrive more musically and easily when their volume is pushed. They are capable of rounder, warmer lows, gain-infused mids, and harmonically rich, pleasant-sounding highs. On the other hand, they tend to be heavier, more fragile, and bigger than solid-state amps. Finally, they can add a retro flavour to any recording or live rig.
What Are The Best Guitar Amps To Plug Your Synth Into?
When talking about guitar amplifiers to plug synthesizers into, we need to bring taste to the conversation. Indeed, much of your decision shall depend on what you want to achieve and what your musical taste is. Let's take a look at some basic indications so you can make a more informed decision.
Fender Twin Reverb
Throughout the 50s, 60s, and 70s, most electric pianos (Wurlitzers, Fender Rhodes, etc.) and early analog synths were amplified with regular, valve-driven guitar amplifiers. Yet, not every tube amp filled the bill; those that got used the most were big valve amps such as the Fender Twin Reverb.
This is because valves will give enough warmth and overdrive to make the sound colourful and alive, while the high wattage will make the synth sound loud without going full-on distortion. This way, you have the best of both worlds.
The Roland Jazz Chorus has been the go-to option for most players, requiring pristine-clean, powerful, articulate, and utterly defined sound in large stages. These qualities come from the amplifier's preamp section, dual 12″ speakers, built-in Chorus, and overall sound quality. If you are after that clean, powerful, and glass-like sound popularized in the 80s, the JC-120 will be a superb option.
Guitar amplifiers are perhaps the most common type of instrument amplifier in existence. They can even be used for instruments other than guitar, as we've found out. As a synth player, you are now ready to make an informed decision and get the one that suits your sound the best.
Related article: Are Synthesizers Considered Musical Instruments?
When buying a synthesizer, it can be challenging to choose the most ideal option within your budget. For this reason, I've created My New Microphone's Comprehensive Synthesizer Buyer's Guide. Check it out for help choosing the best synth for your applications.