Carlsbro Viper Range

With increasing numbers of players turning to lightweight bass cabinets and relatively small Class D amps that fit in a gig bag, it would appear that Carlsbro is bucking the trend with its current Viper range of amps and cabs. Carlsbro gear has always been affordable, and in the current financial climate, this is no bad thing. A quick glance at the prices of these amps and cabs shows that Carlsbro is primed to take on all comers in the mid-range sector, but ultimately it comes down to sound and tonal flexibility, along with durability on the road and portability. With so many factors to consider, it will be interesting to see if these units deliver the goods.

Build Quality

There is no disputing that these are weighty beasts. These cabinets are not only heavy, but also cumbersome – as removing them from their packing boxes proved. The cabinet’s dimensions mean that, rather than being tall, narrow 4x10s, these particular cabs are wide and a real armful – so approach moving them as a two-man job. The cabs have spring-loaded side handles while the amps have a side carry handle: you’re well advised to use two hands to carry these amps.

Carlsbro Viper 350 head

All four units are covered in black vinyl and come fitted with protective metal corners, while the cabs have hard metal grilles to protect the speakers. The whole package looks and feels incredibly sturdy: this range has certainly been designed for life on the road and will stand up to the rigours of being lugged in and out of venues. Both cabinets are assembled from MDF and come fitted with Carlsbro’s own Powertone speakers, plus dual porting at the rear to improve the bass frequency performance from each cab. Strangely, neither cabinet has an attenuator control to vary the tweeter’s influence on the overall sound: presumably this is a cost consideration, as it obviously takes some control of the overall sound away from the player. Both cabinets are rated at 400 watts (at 8 ohms) but can be linked to achieve a 4 ohm load, each cab. Strangely, neither cabinet has an attenuator control to vary the tweeter’s influence on the overall sound: presumably this is a cost consideration, as it obviously takes some control of the overall sound away from the player. Both cabinets are rated at 400 watts (at 8 ohms) but can be linked to achieve a 4 ohm load, which in turn makes more efficient use of the headroom available from each amp.

Both amps have been designed with the same front end and features: the only real difference is the output level and a minor difference in weight. A pair of active and passive jack inputs are followed by the Pre Amp Gain control and a fixed 3-band EQ, offering 18 dB of cut and boost at 50 Hz (Bass), 500 Hz (Mid) and 10kHz (Treble). The switchable graphic EQ offers an additional cut and boost of 15 dB across nine frequency bands, and the faders feature red LEDs.

The master volume control is followed by a Clip LED indicator and a switchable Mute facility, whose LED is lit when in use. A quick peek at the back panel shows the customary speaker outputs (two 1/4-inch jack sockets), a Balanced XLR DI output, Send and Return sockets for any effect units, and a 1/4-inch input for the footswitch.

Sound Quality

Let’s start with the Viper 350 amp and the Viper 115 cab. Initial impressions are that this 350-watt amp is no shrinking violet in the volume stakes. With the EQ and an active Musicman Stingray both set flat, the volume levels are impressive. The tone is straightforward, rounded with some power, a smooth mid-range and not too much distinction in the top end. Bringing the three-band EQ into play starts to add some tonal variety, and boosting the bottom end with a little extra treble pays dividends. Although you may not expect a great slap tone, what this combination is producing is perfectly adequate.

Carlsbro Viper 500 cabsFingerstyle is really where this combination is at, particularly with a passive bass and an electro-acoustic. The amp really responds to different degrees of attack, so whether you play gently or like to dig in, the amp conveys the difference in approach.

Pairing this amp with the Viper 410 is a decent match, the 4×10 configuration offering a slightly quicker response with a noticeable increase in sound projection, although it should be noted that both cabinets have the same dimensions. The 4×10 certainly makes the tone shaping intricacies stand out: fine-tuning your tone to different live situations is easier with this set-up. Boominess and problematic mid-frequencies can be difficult to manage, but a graphic EQ such as this makes the task much easier. As we expected, this combination was a more colourful proposition, with the top end really cutting through with extra definition and clarity.

Switching to the Viper 500, all of the above applies, but with this head you have to bear in mind that the amp at full tilt is more powerful than either cabinet. When pushing the amp louder, there will come a point when the sound starts to break up and an additional cab will be required to spread the load. In use, the Viper 500 doesn’t sound any different to the Viper 350, certainly not to these ears anyway, so there is obviously some consistency.

With both cabinets linked to create a four-ohm load, this is a serious stack. Opting for the industry standard 15-inch cab underneath the 410 cab, the 350 amp shifts some serious air. The tone is big, brash and powerful. The combination of both cabs provides a solid bottom end counterbalanced by the brighter performance of the four 10-inch drivers.

Using the Viper 500 and both cabinets in a marquee, there’s no disputing the power and brute force on offer, but when paired with some well-equipped active basses, a few shortcomings became apparent. For example, the signature sound of these basses was somehow missing and the overall tone lacked finesse and articulation. Sure, the signal was more than loud enough, and even in a tone-sapping marquee, this rig put in a fine effort. Despite the tone shaping facilities on offer, however, it failed to convey the tones that these basses are capable of. The top-end display also seemed very clunky.


The Viper range is worth investigating if you are looking to buy your first stack. The 350 amp and a cab will get you out there playing, but which cab to pick is purely a matter of choice. For our money, the Viper 500 matched with the 4×10 cabinet would be a wise choice, giving you enough power to deal with all scenarios, with the flexibility to add another cab. In terms of looks, the whole set-up is a bit plain; the EQ faders felt cheap and cheerful, although the EQ LEDs are a good touch. As with all gear, it is a tossup between price, sound and portability, and what you gain with one, you may lose on another. That’s why smaller, powerful equipment has a higher price tag. If you’re starting out and finances are a consideration, then certainly give this range a try.

Technical specification


PRICE | £249 / £319

MADE IN | China

CONTROLS | Preamp input gain, equaliser (bass, middle, treble), graphic EQ selector, 9-band

GRAPHIC EQUALISER | 32Hz, 64Hz, 125Hz, 250Hz, 500Hz, 1kHz, 2kHz, 4kHz, 8kHz, post amp master volume, mute selector

INPUTS | 1/4-inch instrument inputs (passive & active), 1/4-inch footswitch

OUTPUTS | 2 x 1/4-inch jack outputs (8 ohms), XLR DI output, 1/4-inch FX send and return sockets

POWER | Output 350 watts at 4 ohms / 500 watts at 4 ohms

DIMENSIONS | 123mm (H) x 467mm (W) x 368mm (D)

WEIGHT | 14.88 kg (32.80 lb) / 15.18 kg (33.46 lb)

BGM rating

Build quality | 7/10

Sound quality | 6/10

Value | 8/10

What we think

PLUS | Affordable and powerful, good tone shaping options, more than capable of doing a good job in a live setting

MINUS |The cabs are too heavy and cumbersome with outdated visuals

OVERALL | Definitely worth investigating if your budget is limited and you need roadworthy equipment with power

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