Acoustic modelling, preamp and effects in a handy DI Box

A3

This is hardly an original thought, but every time I’m presented a new piece of gear I’m amazed at the increased processing power and portability of effects these days.

The latest proof of this observation to cross my desk is the Zoom A3 pedal which combines acoustic modelling, a pre-amp and effects in a handy DI Box all for a street price of $199. There’s a lot going on under the hood of the A3, so I’ll discuss it’s features and then go into the specifics of the unit.

Build

The unit is built like a tank and should have no problem handling the rigors of a live show.

Ins and outs

The right hand side of the pedal has the input jack.

A3 inputs

The pickup select feature is a complex EQ function that compensates for various frequency peaks and valleys that occur with piezo and magnetic pickups. The flat setting bypasses that EQ curve.

The left side of the pedal features mono or stereo outs for live use or for recording. The left MONO jack doubles as a headphone jack so you can connect your headphones as well. There’s a USB port in the unit as well in the event that any firmware updates occur.

A3 back

The A3 allows you to plug a microphone in and the balanced XLR output allows you to use the pedal as a DI box. There’s a ground switch to eliminate ground loop hum.

Power

While there’s a DC 9v in, the A3 can be powered by the USB input or by batteries (up to 8 hours continuous use on 4 AA batteries and 5 hours when the +48V phantom power is being used for the mic input).

The Pre-amp

pre-amp

The front panel of the A3 is where all of the pre-amp controls can be accessed. In addition to a 3-band EQ for bass, middle and treble controls you can use the mic and pickup knobs to mix the level of multiple input signals. The balance knob controls the mix of pre-effect and post effect signal and master controls the master volume.

The center screen displays the model being accessed or the effects in the current signal chain.

The preamp is very quiet. The Zoom specs quote a –100 dBm noise floor and a 120dB signal-to-noise ratio.

The Models

Body Types

The A3 features an “acoustic remodeling function” that’s designed to restore the tone of various body types and specific instruments. Simply choose the closest body type and the model that most closely matches the guitar you’re playing and then use the balance knob to dial in the levels of the direct signal and the modelled signal.

Below, I’ve listed the body types and the models that were used.

Dreadnought
D-28 – Martin D-28
D-18 – Martin D-18
D-45 – Martin D-45

Orchestra
OM-28 – Martin OM-28
OM-18 – Martin OM-18
OM-42 – Martin OM-42

Triple 0
000-28 – Martin 000- 28
000-18 – Martin 000-18

Double 0
00-21 – Martin 00-21
00-18 – Martin 00-18

YMH
LL36 – YAMAHA LL36
LL66 – YAMAHA LL66

Silent
To be used with non-chambered silent guitars – no specific models

12 Strings
12Strings – Guild 12-string guitar

UprightBass
Upright Bass based on the body characteristics of a 3/4 upright bass

Nylon
Nylon Strings – any nylon string guitar

Resonator
Resonator – Dobro resonator guitar

Single Cutaway
314ce – Taylor 314ce

Mold Body
(Actually this is not for moldy guitars but for resin based molded bodies like Ovations.)
Adamas – Ovation Adamas
Legend – Ovation Legend

Parlor Body
LG-2- Gibson LG-2
LG-0 – Gibson LG-0

Jumbo Body
SJ-200- Gibson SJ-200
F-55 – Guild F-55

Square Shoulder
Hummingbird – Gibson Hummingbird
Dove – Gibson Dove

Round Shoulder
J-45 – Gibson J-45
Advanced Jumbo – Gibson J-45 Advanced Jumbo
J-160E – Gibson J-160E

Effects

The A3 ships with over 40 onboard effects that include various eqs, noise reduction, compressors, modulation effects, reverbs, pitch shifters and mic modeling. There’s a tap tempo feature to change all of the time based effects in real-time on stage as well. You can use the effects in any order but (as of this writing) you can only use 2 effects at a time. I’ve included a list of the effect type (Dynamics/Filter, Modulation, Delay, Reverb and Microphone Modelling) below.

[DYN/FLTR]
There are 5 different types of compressors in the unit:
Comp – MXR Dyna Comp.
RackComp – A rackmount style compressor
M Comp – a Zoom compression effect
OptComp – Based on an APHEX Punch FACTORY
SlowATTCK – Similar to a Boss SG-1 Slow-Gear

ZNR – A Zoom noise reduction effect

GraphicEQ – 6-band equalizer
ParaEQ – 2-band parametric equalizer.

Exciter – based on a BBE Sonic Maximizer

AutoWah

[MOD]
Tremolo
Phaser
There are 5 different types of chorus’ in the unit:
Chorus
Detune – chorus with detuning
SilkyCho – 2 bands of detuning and chorus
MirageCho – a shimmering chorus effect
StereoCho – stereo chorus
Flanger – based on an ADA Flanger
PitchSHFT – pitch shifter

[DELAY]
There are 5 different types of delay in the unit:
Delay – up to 4 seconds of delay
ModDelay – delay and modulation
ReverseDL – This reverse delay is a long delay with up to 2 seconds of delay
MultiTapD – multiple delays and delay times
StereoDly – stereo delay with separate the left and right delay times
StompDly

[REVERB]
HD Reverb – a high-definition reverb.
Hall – based on the reverberation of a concert hall
Room – based on the reverberation of a small room
TiledRoom – based on the reverberation of a tiled room.
Spring – spring reverb.
Arena – based on the reverberation of an arena
EarlyRef – from Zoom – “This effect reproduces only the early reflections of reverb.”
Air – This effect reproduces the ambience of a room, to create spatial depth.
ModReverb – Reverb and modulation
SlapBack – A repeating echo effect
HD Hall – a high-definition hall reverb.
Plate – plate reverb.

[MIC]
all mic models simulate the sound of miking a guitar
Dyna 57 – Shure SM57.
Cond 414 – AKG C414.
Cond 87 – Neumann U87.

Anti-Feedback Switch

If you’ve ever played a live show, you know what a problem feedback can be! With the ANTI FEEDBACK footswitch you simply engage the switch and the A3 finds the frequency that’s feeding back and applies a complex notch filter to it. This can be repeated up to three times to notch 3 different frequencies, thus cutting out feedback while only minimally affecting overall EQ.

Boost Switch

Getting lost in a mix is no fun. Engaging this feature gives up a clean boost up to 12 dB to help get your sound front and center.

Guitar Tuner

Engaging the onboard chromatic tuner mutes the output signal as well (so no more tuning noises bleeding through the PA!)

Patch saving

You can save each one of your sounds and sequence them in whatever order you like so you can change tones in real time.

In use

This is a box that does a LOT and does the majority of it very well. There are, however, some caveats to think about when considering this pedal.

  1. The modeling is cool but more subtle than the term ‘modeling’ might imply. Don’t expect radical Variax™ type differences between the body types. In this regard the A3 feels more like a complex set of eq curves applied to your signal than true modeling.   Having said that, it’s fairly easy to find a base complimentary tone to the signal that you’re using.
  2. The A3 appears to be a more of a live pedal than a recording DI. You can record directly with the A3 and it will sound much better than plugging your piezo pickup out into a DAW interface, but it really doesn’t sound the same as a guitar recorded with multiple mics.
  3. The two effect limit is a problem. There are sonic enhacers of all types on this pedal, but when going from the A3 into a live sound board – you’re likely to need additional gear to get the sounds you want. Many online users keep pointing to the USB port and the ability to upgrade firmware as a sign that Zoom might add additional effects capacity to the pedal – but I don’t think that’s something that can be relied on.
  4. This is definitely a tweakers pedal. Many of the controls are not intuitive and while the manual has a lot of good information it’s not going to help some people with the pedal. If you want a simple plug and play pedal – you’re going to be disappointed.

Those are some concerns, here are the positives.

  1. It’s small, portable and built like a tank. For live use, 8 hours on AA batteries is pretty amazing as well.
  2. The integration of features of the pedal is awesome. The modelling sounds good. You can blend the sound of almost any parameter. The tuner works well and the boost and anti-feedback features performed flawlessly for me. As an acoustic DI alone, this is worth the money.
  3. The effects sound really good.  The fact that they were willing to include some non traditional acoustic effects (like reverse delay and auto-wah) into the pedal is a nice addition as well.

Ultimately, the positives outweigh the negatives by far on this pedal, but understanding what the pedal does and doesn’t do will help manage expectations when purchasing it as well.

Bonus section – tone hacks!!!

One thing to consider with a pedal like this is that Zoom has put a lot of concentrated effort into maintaining an acoustic sound in a digital realm. For those of you looking for something a little different, consider that working against the modeling chains will produce all types of different sounds. Try mismatching input options with the pickup you’re using and/or mismatching body types with the instrument you’re playing. Adding in some extreme effect parameters – you might start getting into tones that have very little to do with the tone of your instrument.

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Scott Collins (64 Articles)

Scott Collins is the author of the pedagogical/reference series, The GuitArchitect’s Guide To: and several e-book titles that include: An Indie Musician Wake Up Call and Selling It Versus Selling Out. His playing is inspired by a wide range of western and non-western music, and, as a performer, he specializes in real-time composition.