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January 2010
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Line 6 LowDown HD750

Modelling bass amplifier

Published in PM September 2009
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Reviews : Guitar: Amplification
Line 6 are famed for their innovative guitar products, but this month we take a look at an amp aimed specifically at bassists — the LowDown HD750.
David Heap
Renowned for their innovative modelling techniques, Line 6 have now been in production for over a decade, having launched in 1996 with the AxSys 212 guitar amplifier. The digital processing within this circuitry allowed the user to choose various pre-determined voicings of well-known amplifiers. The company became very successful when the modelling was separated from the amp and marketed as a standalone unit — the Pod.
Currently Line 6 have a wide selection of products available, from pedals to amplifiers and guitars, with the capability of a combo to sound like a 4 x 12 or an electric guitar to emulate an acoustic. The versatility of the range is confirmed by the end-user list, with artists as varied as Eddie Van Halen, The Edge and Eric Clapton all using the brand.
The Line 6 LowDown HD750 is a 3U, rackmountable bass amplifier. It has a front of polished aluminium with a sturdy chrome handle at each end, while all the controls are secured to a slightly recessed black panel running along the bottom half. To the left are jack sockets for passive and active instruments, next to which is the six-way rotary Amp Model selector switch, which dials in the required initial starting tone — Clean, R&B, Rock, Brit, Grind or Synth. This is where the modelling starts. Clean provides warm lows and punchy highs, and is based around an Eden Traveler. R&B is attributed to a ‘68 B-15 flip-top, the type of sound heard on ‘60s and ‘70s Motown records — clean, fat and punchy. Rock represents a ’74 Ampeg SVT head and 8 x 10 cab, while Brit delivers the sounds of a ’68 Marshall Super Bass. Next up is Grind, a distorted SansAmp PSA-1 into an SVT with the direct clean signal mixed, producing that angry, clear, punchy aggression heard on many modern tracks these days. The final position is Synth, modelled on a classic ‘70s bass synth. In this mode the tone controls take on different functions to the norm. Running along the top of the panel are six illuminating push buttons: the left-most Deep button adds a very low pre-shape tone, ideal for playing at quieter volumes, while to the far right is the Tuner. This button, as with most controls on the front, has the added function of acting as an input clip indicator. Between these two are four more buttons for the Channel Memories A, B, C and D — four programmable channels to save custom settings. Below these are the tone-shaping controls. The first, Drive, acts as a gain control and is used to add that bit of distortion when required. Following on are Bass, Lo-Mid, Hi-Mid and Treble. To the right of these are the Channel Volume, Opto Comp (a compressor) and Smart FX controls (where you can dial in a Filter, Octaver or Chorus), and finally a Master volume knob.
As hinted earlier, most of the controls have a dual function. When the tuner is depressed the Channel Memory lights become tuning indicators, with the centre two turning green when the correct pitch is reached. The LEDs around the Amp Model switch indicate the string being tuned.
In Synth mode, the Bass control becomes Cut-off, Lo-Mid adjusts Resonance, the Hi-Mid knob controls Envelope, Treble controls Attack/Decay, and Opto Comp becomes Waveform.
The rear panel carries the power socket and accompanying switch, alongside which are a mini-jack input (for connecting an MP3 or CD player), and footswitch and headphone sockets. Below these is an XLR DI output, for sending the modelled tone to a desk or recorder, and a jack socket, which outputs the pre-model sound. Two Speakon sockets are supplied to connect to speakers, down to a minimum load of 4Ω.
In use
The LowDown HD750’s back panel houses the DI, thru and headphone outputs, as well as parallel Speakon outputs and a Cat 5 socket, for use with one of Line 6’s optional floorboards.
The LowDown HD750’s back panel houses the DI, thru and headphone outputs, as well as parallel Speakon outputs and a Cat 5 socket, for use with one of Line 6’s optional floorboards.
In use each of the preset models bears a true resemblance to its real-life counterpart. Clean is just that; a lovely, clear sound that can be tweaked with the tone controls or dirtied to taste with Drive. R&B produces a faithful representation of that lovely Motown sound — plug in a Fender Jazz and you too could sound like James Jamerson. Rock is my favourite, being biased towards Ampeg, and being able to dial in that great big wall of sound at low volume is a real bonus for those smaller gigs or for studio work. Again, the Brit model sounds just like those early British bass tones like Cream or the Who. Catering for the more adventurous, Grind starts with a degree of punchy distortion as heard in such bands as Alice In Chains and Rage Against The Machine. As a mere bass player I have never quite understood the build up of tones in a synth, but Line 6 have put a preset in the channel memory, which is a good starting point for further tweaking.
The first position of the Smart FX switch brings in an envelope filter based on a Q-Tron, as heard on many major funk and rock tunes. The Octaver is modelled around the EBS OctaBass, and brings in a note an octave below the one played. Turning the knob increases the effect’s volume against the dry signal. This is a brilliant effect, great for the odd little solo or to add that hint of low end in slow, moody tracks. Finally there is the Chorus, which is based on a TC Electronic unit and produces a clear, expressive effect that again can be adjusted to suit. This is a great effect that faithfully follows the original TC model, and it sounds superb on a fretless.
Footswitch options
There are three control pedals available for use with the LowDown: the simple, two-switch FBV2, for scrolling through the channels; the more complex FBV Express, which has four switches (one for each channel); and a foot pedal for volume or wah effects, the latter being based on a vintage Tycobrahe ParaPedal Wah. Holding down both channel one and two footswitches turns on the tuner, and tapping any of the four switches reverts back to normal mode. With the top-of-the-range FBV Shortboard, most of the front-panel controls can be accessed. It also adds nine memory banks for each of the channels, should it become necessary to save numerous settings. This also has a volume/wah expression pedal.
This is a really great bit of kit with plenty of usable tones and loads and loads of power. It looks good, too — though there are a few minor niggles. As a rackmount unit, I do feel the power switch should be on the front panel, particularly as the rear-mounted fan remains on at all times and is quite noisy. In a studio it would need switching off, or simply unplugging with the unit still turned on. My only other concern is the Amp Model select switch, which would, in my opinion, be much better detented on the six positions.
The beauty of Modelling amps is their ability to create a big, powerful tone at low volume, which is very handy for smaller gigs or in the studio, where you won’t have an engineer shouting at you to turn the volume down. The range of equipment available from Line 6 is now quite extensive and, having used a Bass Pod in the studio on many occasions, I can recommend their modelled tones as being very authentic, with the ability to colour as required. The LowDown HD750 is another excellent addition to the product range, and thanks to its splendid value, it should sell well even in this depressed market.  0

Published in PM September 2009
Line 6 LowDown
HD750 £240
Designed in America but built in China, this latest modelling bass amp from Line 6 provides an impressive feature set at a very reasonable price point.
Line 6 Europe
+44 (0)1327 302700
Tech Spec
LowDown HD750
Five amp models (Clean, R&B, Rock, Grind, Synth).
Smart Control effects section (Filter, Octaver, Chorus).
Optical compressor.
Four-band EQ.
Active and passive inputs.
Parallel Speakon speaker outputs (750W @ 8Ω, 325W @ 4Ω).
Built-in tuner.
FBV foot pedal input.
Dimensions (WDH): 483 x 241 x 133mm.
Weight: 9kg.