Gear review: Howling Wolf Slapkat 600

2_webDavid Etheridge discovers a hand-built amp and cab which take a drastically new approach to bass sound

Handmade amplifiers from small boutique manufacturers are less common than bespoke basses. So when I recently came across the new Slapkat 600 watt amp at a Midlands guitar show, I was intrigued to say the least.

Build Quality and Features

The Slapkat 600 is an imposing brute on first sighting, set into a solid pine case, with brass corner plates, a leather carrying strap and bristling with features on both the front and back panels. On the front is the main input with LED mute button, pre EQ FX loop, three parametric EQ sections offering a whopping +/-16dB of control over 35-220 (low), 120-820 (mid), and 560-3kHz (high), an extra gain control for the compressor, which can also be controlled from the EQ section, a post EQ FX loop, and master volume pot (which goes up to 13!) with comp/lim in/out pushbutton.

On the rear panel, things get very interesting indeed. As well as a power switch, Speakon connector and DI XLR sockets, there’s a range of inputs and outputs. Most intriguing is the ‘click’ section: a separate in/out section for additional pickups (developed for a local rockabilly double bassist who wanted full control of the slap portion of the sound, hence the Slapkat moniker), a three-way power amp source select switch, and three separate outputs for the amp to external sources: full amp, and low and high outputs with adjustable crossover frequencies (120-1kHz).

The accompanying cabinet is just as impressive, in a solid pine enclosure with brass corners and carrying handles (it’s a two man job just to lift it). Inside are four Celestion BL-200x drivers and a sealed port at the base, offering a total of 800w into 2Ω.


Sound Quality

Switch on the whole system and prepare to be amazed. It’s the very flexibility of all the features that provides waves of sound in spades here. You can explore the settings for weeks and still be coming up with new tones. At times the Slapkat can be soft, smooth and purring, at other times a hooligan of an amp with raucous and floor shaking waves of sound. The EQ section is flexible to a fault, adding tones to your bass that you might not have guessed at, while the feedback modes provide clean, vintage and smooth overdriven modes with ease. Above all, the sound is supremely warm and rounded in all cases. Add the compressor and the amp seems to take on a life of its own, and bear in mind that there’s an awful lot of interplay between the EQ and compression sections for sounds you might not have come across elsewhere. With the ‘click’ input there’s tremendous scope for blending sounds from your instrument. With this prototype model, it’s set up for only one type of piezo pickup, but future amps will offer other pickup capabilities. This has potential for not only multiple pickups on electric uprights, but also stereo pickups on any bass, and the click input will probably be mounted on the front panel for ease of use in the future.


This is an extraordinary amp – big, muscular and distinctive, bristling with features, providing possibly unrivalled tones, power and general bang for the buck. It’s not cheap (bespoke handcrafted products seldom are), but represents excellent value for money for the bassist who wants something really different, and offers all sorts of possibilities for investigating alternative pickup combinations and blends.

Technical Specifications

Price | £999 (amp) £799 (cab)

Made in | UK

Power | Output 600w RMS into 2Ω, 150w RMS into 8Ω

Features | Input (with mute), 3 section Parametric EQ: +/- 16dB Low: 35-220hz; Mid: 120-820Hz; High: 560-3kHz. 2 send return loops: pre and post EQ. Comp/limiter switch, click transducer input and output, DI out XLR, active crossover outputs with adjustable frequencies 120-1kHz, VU LED ladder. Three output modes: constant voltage, valve sound, constant current, microprocessor for thermal management and speaker protection, Speakon connector to cab, 2 years RTB warranty

Speakers | 4x 10” Celestion BL-200X drivers (200 watts each, 800w total)

Weight Head 14kg; cab 38kg

Dimensions | Head: 200mm H x 560mm L x 320mm D. Cab: 900mm H x 640mm W x 320mm D

What We Think

Plus | Immensely strong and powerful amp loaded with features

Minus | Not the sort of thing you can easily throw into the back of your car

Overall | Classy and innovative, offering tremendous flexibility

BGM Rating

Build Quality 9/10

Sound Quality 9/10

Value 9/10

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