Review: Yamaha THR5A Amp is an Offstage Amp with Impressive Tone and Effects

With battery or external power options, powerful software effects, and a small footprint, this amp has a lot of potential for home practice sessions, in the studio, or even for a house concert or quiet gig.

These days, performing with an acoustic guitar often means playing plugged in. Musicians play amplified everywhere from concert halls to coffee shops, so it’s not surprising that many acoustic guitarists also want to plug in at home. You may want to practice under conditions that are similar to the way you perform, use such electronic accessories as loopers or effects pedals, or just enjoy the larger-than-life sound of an amplified guitar. But when you’re practicing at home, do you really want or need the same amp or PA system you use in a club? Yamaha is betting you don’t, and so has introduced a line of tiny, ultra-lightweight, battery-powered amplifiers designed for offstage use. The THR series of amps was initially aimed at electric guitarists, but the new Yamaha THR5A brings the concept to acoustic players as well. I got an advance look at a prototype.

Yamaha THR5 amp

Tiny, Self-Contained Amp

The THR5A is shockingly small, resembling a lunch box more than an amplifier. When you first see it, you might assume the box is just the head and start looking for the speaker cabinet, but it’s all self-contained—the unit includes a pair of tiny three-inch speakers. The next surprise comes when you turn the amp on, and the warm glow of tubes slowly fades in. What? Not really—the glow is from LEDs, but the look is quite convincing. If you find the idea off-putting, the LED effect can be turned off. But perhaps the ultimate surprise comes when you plug in and play through the amp. The sound may not rival a full PA or high-powered amplifier, but it’s pretty difficult to believe the room-filling sound and volume are coming from two tiny speakers.

Efficient Controls

The THR5A’s inputs and controls line the top of the box, starting with the power switch, a ¼-inch input jack, stereo auxiliary input, and headphone output. A five-position switch allows you to select from different mic models, including Condenser, Dynamic, and Tube, as well as a Nylon setting and a Clean electric guitar mode. A Blend control allows you to set the mix between the straight guitar sound and the modeled tone. The amp has a confusingly named Master volume, which actually appears to be input gain (or channel volume), as well as a Volume control, which affects the overall output level. (When recording, the Master volume affects the signal sent to the USB output, while the Volume affects the sound coming from the speaker.) There is a single tone control, and a pair of effects knobs that allow you to dial in various combinations of chorus, compression, reverb, and delay. The amp also includes a button that activates a built-in tuner and provides a tap-tempo switch for the delay.


The effects controls are unusual in that they combine multiple effects in a single knob. For example, the DLY/Rev (delay/reverb) control is off when fully counter-clockwise, bringing in progressively louder delays when turned clockwise and gradually adding reverb. Turning the knob further moves to a hall reverb with no delay, starting with a low mix and adding more and more reverb as you continue to turn clockwise. The compressor/chorus knob acts similarly, with compression increasing as you turn the dial, morphing into chorus. The approach requires a bit of getting used to but works quite well in practice.


Computer Connection

It’s easy to have so much fun playing with the THR5A that you never get around to connecting the amp to a computer, but that would be a big mistake. The USB connector allows the THR5A to act as an audio interface, bringing its stereo sound, effects, and mic models to almost any recording software. In addition, Yamaha supplies a computer editor that allows you to manipulate the amp, save banks of presets, and access more controls than the physical knobs on the amp do.

The software, which works on PC and Mac, provides three bands of EQ, bass, mid, and treble, and extensive controls over the reverb, delay, and other effects settings. There are multiple reverb algorithms with extra goodies like predelay, and much more. The reverb, for example, can be dialed all the way up to a remarkable 20-second decay time! There are also effects that are only available through the software, including flanger, phase shifter, tremolo, and a noise gate. You can use the extra controls to dial in a variety of sounds and save presets in the software. Unfortunately, unlike with some of the electric versions of the amp, you cannot save or access any presets directly from the THR5A, so you’ll have to stay connected to a computer to take advantage of the extra features.

One of the interesting side effects of using the computer editor is that the software controls change as you move the physical knobs on the amp, providing useful insight into what the knobs actually do. In nearly all cases, turning the physical knobs corresponds to multiple changes in the software controls. For example, it’s easy to hear that the tone control gets brighter as you turn it clockwise. Watching the software dials as you move the tone control reveals that this not only increases the treble but alters the bass and mids in a way that is far from obvious.  The behavior of the two effects controls is even more complex.


Impressive Volume and Tone

The biggest questions about a small amp like this are “How loud is it?” and “How good does it sound?” Volume is the simplest to answer. The amp is probably as loud as anyone would need in a living room or bedroom and might be loud enough to use at a quiet coffeehouse gig. With a low-output passive pickup, like a K&K and McIntyre Feather, the amp produced a sound that was roughly double the acoustic volume of my guitar—plenty loud enough with the amp sitting on a table in front of me. Switching to a higher output active pickup, a D-Tar Wavelength, I was able to drive the amp substantially harder, and the volume was more than I would ever need at home.

Sound quality is subjective, but it’s hard not to be impressed with the sounds Yamaha manages to produce through the tiny built-in speakers. The amp tends to accentuate the midrange, but overall, the sound is quite natural and pleasant. But the THR5 really comes alive when you activate the effects. The reverb sounds stunning, creating the uncanny illusion that the sound is coming from a bigger space somewhere beyond the tiny amp.

When used as a recording interface, the THR5A offers a lot of potential. I found the recorded sound, again, to be somewhat midrange heavy, but with all the modeling, stereo simulation, effects, and tone-shaping options, it was easy to dial in a sound that was leaps and bounds better than a straight pickup recording.

The Ultimate Bedroom Amp?

Yamaha’s positioning of the THR5A as an offstage amp seems absolutely accurate. At first, the small speakers and modest volume may seem limiting, but the amp has a lot of potential for home practice sessions, in the studio, or even for a house concert or quiet gig. It’s fun to hear the produced sound added by the impressive effects. The volume might not fill a club or compete with a drummer, but it’s more than enough to help you match the volume of a fiddle, banjo, percussionist, or group of vocalists at a practice session. With its battery power, the THR5A is a tempting choice for busking, although there is a limit to how much air the small speakers can move in an open space. But in the living room, bedroom, or studio, the THR5A can fill the room with a rich, spacious sound that’s sure to please.


AMP: Dual five-watt amplifier; 1/4-inch mono guitar input; 1/8-inch stereo auxiliary input; headphone output; powered by included adapter or eight AA batteries; 10.7 inches x 6.5 inches x 4.7 inches. 4.4 lbs

SPEAKERS: Pair of 8-cm (3.2-inch) speakers

OTHER: Tone and volume controls; four mic simulations; effects include compression, chorus, flanger, phase shifter, tremolo, delay, reverb, and noise gate; built in tuner, tone, and volume controls; USB computer interface

PRICE: $200 street

Doug Young
Doug Young

Doug Young is a fingerstyle instrumental guitarist, writer, and recording engineer. He is the author of Acoustic Guitar Amplification Essentials.

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