Having made waves in the world of bass amplification, Markbass now turn their attention to the lucrative acoustic sector. Mark Tucker reports...

Introduction
What is it with Italy and amp designers? Mark Bass are yet another Italian amp designer primarily aimed at (as you would imagine) the bass player, yet more recently Mark Bass have designed some dedicated acoustic combos, namely the AC101 and AC601 – the latter being the model for review.
   
Marco De Virgiliis, designer of Mark Bass amps, claims to have a clear aim to produce top quality acoustic amps that meet the needs of professional musicians everywhere. He wants his amps to be compact, lightweight, and now with the availability of high-quality components, Marco claims he was able to achieve his ambition.

First Impressions
At first glance, the appearance of the AC601 to me did not have that aesthetic flair that some other Italian designs offer. That’s not to say the AC601 is not appealing in its appearance. Quite the contrary, and with its small, almost weenie proportions; about a foot square, amps don’t get much smaller than this. Covered in textured black vinyl, the AC601 looks incredibly simple and straightforward, something the cubed effect and foam grill face only enhance. The amp looks as if it will take the knocks, especially at the front with its foam frontage concealing a strong steel grill that protects the speaker and tweeter.

Features
Like many other acoustic amps we have had for review recently, the AC601 is a simple, twin channel combo designed to amplify acoustic guitar and/or a microphone signal. Really, it’s a mini portable PA system. Each of the AC601 and 101 combos are powered by 250W of power into a 4 ohm cabinet, or 150W into an 8 ohm cabinet. The AC601 features a custom designed 6” B&C neodymium speaker and one HF compression driver, while its bigger brother the AC101 is fitted with a 10” B&C neodymium speaker and one HF compression driver. Channel Two has the option of either a microphone XLR or jack instrument socket, albeit with only high and low-frequency cut and boost controls. This channel also has the addition of the VPF Filter, a variable pre-shaped filter that can be bypassed. This can boost frequencies at a fixed amount at 35 Hz and 10 Khz, while allowing fixed reduction of the mid frequencies at around 380 Hz. However Channel One’s input is suitable only for signals fitted with quarter inch jack sockets, yet this channel boasts the extra mid frequency control. All tone controls offer cut and boost totalling a massive 16db at the fixed frequencies; 40 Hz, 600 Hz and 6 KHz and with the impressive frequency response of the AC601 ranging from 55Hz to 18Khz, this tiny amp should technically be able to deliver good broad ranging results with both voice and guitar, or just about any signal that is fed into it.
   
Both the AC601 and 101 offer a simple selection of preset effects including; Chorus 1, Room, Reverb 1, Reverb 2, Hall and Chorus 2 respectively on a single selector switch with separate mix controls on each channel. Likewise, each channel has its own clip LED together with a separate clip LED on the master output section. Each of these give a clear indication of the amp being overdriven and inducing any unwanted distortion into the sound.
   
Taking a closer look at the rear of the amp, it reveals the typical ‘Speakon’ extra speaker output, while the balanced XLR line out offers independent control of all signals fed through the amp, pre the master volume control. This function is ideal for recording, or for amplifying further via a PA system.
   
An insert point permits the introduction of further multi-FX units, should they be needed.
   
As commonly found on most new amps, the ground switch could get you out of a fix with ground hum problems, particularly when working with PA systems and more complex set-ups.
Glancing at the side of the amp, Mark Bass have kindly fitted the useful addition of a high frequency driver level control. This allows for full control of the level of very high frequency information reproduced from the amp’s HF driver.

Performance
When I picked up the AC601, it felt ridiculously lightweight and I must admit to feeling somewhat sceptical about the degree of tone and punch that could be capable from an amp of this size. This combined with what appeared to be an extremely simple control panel didn’t leave much to the imagination. Yet, when I plugged – what is a particularly average guitar fitted with a bridge transducer – into the 601, the sound immediately came to life. The degree of available tone is quite remarkable, and having not touched the amp settings, this was a good sign. The default settings were significantly cutting frequencies across low, mid and high, resulting in an exceptionally smooth and silky tone. This little beauty has a distinct compressed, yet open tonality that I find extremely appealing. Maybe because of the amp’s ability to produce a very clear sound, and a low tweeter setting being possible, an impressive low hiss sound was achieved. Hiss from HF drivers can sometimes be a problem. Even with the simple three-way tone controls, loads of extra available tones are available to boost across the spectrum, allowing far more extreme sonic results, thus making the AC601 a potent little beast.
   
Considering the size and weight (only 8.8kg) of the AC601, the amp produces ample volume and punch. Even at the point of feedback there was still more available gain before the clip lights became active.
   
The variable filter in particular allowed some pretty radical modification in tonality, which made up for the fundamental difference of the absent mid tone control on Channel Two. The internal effects device is surprisingly good with effects ranging from chorus to room and other reverb settings, they all performed exceptionally well. I was a little miffed by Effect 1 being titled ‘Chorus’ which is in fact chorus and reverb mixed together. This is a shame because the only other chorus setting ‘2’ has a slap echo mixed together with chorus. Despite this small niggle, all the effects sounded rich and smooth. The control knobs perform well offering large and a slightly vintage appearance, resulting in the user feeling in control, with a feeling of fine tweakability.

Conclusion
With my initial feelings being somewhat sceptical, the AC601 very quickly dispelled any fears that this amp was unable to produce good results. The AC601 excelled in every way I could imagine, sounding really great at every level. Whatever was plugged into it sounded superb, which says Mark is indeed doing something very right. This amp does not come cheap and at £749 RRP, some might say it’s downright expensive. With this factor in mind, I find it very difficult to find any faults with the design or sound of the AC601 other than maybe the litho control display colour scheme, and even then, the chosen yellow display is really very clear and functional - which after all is exactly what you need on a darkened stage. If you are looking for ultimate sound quality at ridiculously portable and compact proportions, this is the amp for you. It sounds superb, whatever you plug into it.