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Line 6 Delay & Modulation

Modeller Effects Pedals By Paul White
Published March 2000

Line 6 Delay & Modulation

Line 6 have released two DSP‑based effects pedals that use physical modelling to recreate the echo, delay and modulation treatments of a bygone age. Paul White — who was there first time around — finds out how they measure up to the real thing.

When tape echo boxes were the only game in town we all hated them for their noise, muddy delays, distortion and unreliability. It was only when they were replaced by pristine digital delay processors that we realised the muddiness and distortion was actually an essential part of the tonal magic. With their new range of modelled pedals Line 6 are seeking to recreate that — though since most people don't seem to feel any nostalgia for noise and unreliability they've chosen not to model these particular parameters!

This month I'm looking at the Delay Modeler and the Modulation Modeler pedals, which will shortly be joined by a distortion unit in the same series. The existing units share the same die‑cast stomp‑box format, with a choice of battery power or optional mains adaptor, and all can store a limited number of user programs for recall via one of four footswitches. Each unit also allows an expression pedal to be patched in, for real‑time morphing between two sets of control‑knob settings.

Both the Delay and the Modulation pedals have the same control layout and I/O capability. Their stereo inputs and outputs, serviced by 24‑bit converters, are suitable for mono input and/or output operation if you plug into the left channel only. Sensitivity is preset to suit instruments such as electric guitars, and the inputs have high impedance. There's no input‑level control or metering, so any adjustment must be done by ear.

Unavoidable Delay

The DL4 Delay Modeler not only models classic delay‑based effects but includes a loop sampler.The DL4 Delay Modeler not only models classic delay‑based effects but includes a loop sampler.

As the name suggests, the Delay Modeller is all about echo effects (see 'The Making Of A Model' box for an explanation of the kind of echo processors Line 6 studied during its creation). It offers a choice of 16 effect types, each of which can be modified by five parameter knobs. One of these knobs sets the dry/effect mix, but for any echo effect the two main controls are Delay Time and Repeats (feedback). These two knobs, then, have the same function for every effect model, while the remaining two knobs — Tweak and Tweez — change their function depending on the model selected.

The most complex of the effects provided is not a model at all, but rather a loop sampler offering a maximum 14 seconds of loop time. An original loop can be recorded, then replayed or overdubbed. The loop can be started and stopped at any time and there's even a separate echo/delay parameter that allows echoes of up to 800mS to be added, with pitch modulation if required. There's also the facility to record at half speed, so you can get double‑speed playback, and if this doesn't tickle your weirdness buds, you can also get a loop to play in reverse at half or normal speed. To use all these features you have to remember what the switches do (some functions require a double tap) and you need a decent sense of timing, but the results can be a lot of fun.

The remaining 15 effects are models based mainly on commercial echo boxes, though there's also a rhythmic delay and a number of generic stereo/ping‑pong delays, as well as a seriously weird sound‑reverser. The latter delays everything you play, then spits it out backwards. If you have the will‑power to keep playing and ignore what you're hearing, you can create an amazingly convincing backwards guitar solo with this effect. Other proprietary effects include the Sweep Echo, which was created by combining delay with a swept filter that sounds like a cross between a wah‑wah and a phaser. There's also a pleasantly effective low‑res digital reverb which features adjustable bit resolution of the recirculated signal — anything from 6‑bit to 24‑bit is available. In this model the Tweak knob adjusts the tone of the echo. While it's little more than a dull 'thunk' in 6‑bit mode, some of the 'medium' settings sound wonderfully vintage.

The first 'real' model one encounters is Maestro's EP1 tube tape echo. Tape/tube distortion is adjustable, and you can add a little wow and flutter too. For that early surf sound or general psychedelia this model works very well. Also modelled is Maestro's EP3 solid‑state tape echo, wherein the Tweak and Tweez knobs affect the bass and treble tonality of the repeated sound. The EP3 has a cleaner sound than the tube version but still features a gentle repeat characteristic that disintegrates into mush after numerous repeats, just like the real thing.

Favourites such as the Watkins Copicat and Binsen echo units don't get a look in, but the Roland RE101 Space Echo gets the full Line 6 treatment, complete with individual head‑switching for all four virtual tape heads. Early tapeless echo‑box models are also included, based on the sound of the Boss DM2 and Electro Harmonix Deluxe Memoryman analogue delay pedals — but with up to 2.5 seconds of delay time rather than the half‑second or so of the original. The Memoryman Deluxe model also features a delay modulation capability for creating echo‑plus‑chorus effects.

Of course, no digital delay would be complete without some digital delay emulations. These are not models as such, but some do offer features found in other units, such as dynamic delay (where the delay level is ducked according to the level of your input signal) and Auto Volume Echo (where a slow‑attack envelope shaper is combined with delay).

Everything In Modulation

The MM4 Modulation Modeler includes emulations of classic chorus, phase, tremolo and ring‑modulator effects, though not tape‑based flanging.The MM4 Modulation Modeler includes emulations of classic chorus, phase, tremolo and ring‑modulator effects, though not tape‑based flanging.

Physically, the Modulation Modeler, which offers tremolo, flanging, chorus, and so on, is identical to the Delay pedal, except it's blue rather than green. I suspect that the internal circuitry is also identical, with the exception of the software EPROM.

Guitar‑amp tremolos are often taken for granted, but purists know that they all sound different. Here the Fender Deluxe opto tremolo is recreated, along with that of the Vox AC15, offering just the right amount of vintage thump. Classic phasers based on MXR, Mutron and Ibanez pedals sit alongside a recreation of the Univox Uni‑Vibe, while rotary speakers come in Fender Vibratone and Leslie 145 flavours, the latter having adjustable drive, horn depth and drum depth.

Modelling may not yet be an exact science, but these emulations of classic signal processors sound gratifyingly close to the real thing.

Flangers also feature heavily, with models based on MXR and ADA units, but strangely there's no Electro Harmonix Electric Mistress. This isn't actually a problem, though, as the other models can get very close to the same sound — sans hiss, of course! Chorus lovers will be pleased to find models inspired by the Boss CE1 and the Roland Dimension D, as well as the Tri‑Stereo Chorus, which apparently used three chorus circuits driven via 12 LFOs! The Boss VB2 Pitch Vibrato pedal has also been plundered, for its level‑sensitive modulation rate, and there's a ring modulator that combines both AM and FM modulation for that 'non‑traditional' broken guitar sound. Finally, there's a nice panner which, of course, requires the Modulation Modeler to be used in stereo.

Putting Your Foot Down

Sadly, neither of these pedals comes with a PSU. It's true that most traditional guitar pedals are either battery‑only or the PSUs are optional, but some of today's cheaper multi‑effects pedals come complete with power adaptors, so perhaps this is one vintage practice that should be discouraged? Battery life is reasonable, at 20 to 30 hours from a set of four alkaline 'C' cells, but it could be expensive if this is your only source of power.

Power issues aside, the build quality of the pedals seems good, with a nice strong cast housing and well‑recessed knobs, though I would have liked at least a peak‑warning LED on the input. A non‑slip rubber base prevents the pedals creeping in use, and the switch LEDs are bright enough to see under any practical conditions.

Operationally, I like the immediacy of these units, though — as with all such control systems — the physical position of a control knob won't correspond to the actual parameter setting if you change patch. More user memories would have been appreciated (see the box on page 189), but I can understand why the designers took the approach they did, as it keeps things simple. Also, in the case of most of the models the factory settings are pretty much optimum. With the delay unit, you can always use tap tempo to change delay time.

What matters most is the sound, and though the units are surprisingly quiet it's the subjective success of the modelling that's really going to drive sales. After all, you can now buy budget multi‑effects guitar pedals for around half the price of one of these boxes. Ironically, the lack of tape noise makes it quite difficult to judge the tape echo emulations, but I feel Line 6 have been largely successful in creating delays that disintegrate over successive repeats in the same way that tape delays do. Certainly they get a lot closer to the traditional tape‑echo sound than any other unit I've tried, and they also provide a good range of variations from which to choose. I also love the reverse effect and some of the modulated delays.

Moving on to the Modulation Modeller, this also scores high on the authenticity front. However, although the Line 6 Leslie simulation is one of the best around, it still doesn't quite do it for me in the same way as the real thing. There also seems to be no dedicated speed‑change facility (other than programming two patches at different rates or using a pedal for control), which is a little remiss when you consider that the dynamics of drum and horn speed changes are a vital part of the Leslie sound. The phasers, choruses and flangers, on the other hand, are extremely close to the original analogue pedal sound, while the guitar tremolos exude an air of vintage authenticity. Sadly there's no tape flanger emulation, as nobody has quite cracked that yet, but if anyone can do it I reckon Line 6 can, so maybe that's something to look forward to.

Pedal Power?

In an ideal world, a rack unit combining both these pedals, with two or three times as many adjustable parameters and variable‑gain inputs, would be best for studio use, but these boxes offer the undeniable advantage of great simplicity. Both pedals meet their design requirements both physically and tonally, the delay unit in particular offering something never previously available from digital effects boxes. Indeed, if I had to choose between the two I'd go for the Delay Modeller because of its tape echo emulations, its wacky reverse effect and its loop sampler.

I'm happy to see that background hiss and tape splices that break in the middle of guitar solos have been left in the last century, where they belong, but the tonal magic that made this old equipment sound the way it did has been very closely approximated, making these pedals very musical. The sound quality is certainly good enough for studio use and the ability to accommodate both mono and stereo inputs and outputs means they can be used with keyboards as well as guitars. Providing you take care over signal levels you can also use them in the send and return loop of a mixing console, though most console insert points would probably be a little on the hot side for ideal level matching.

Modelling may not yet be an exact science, but these emulations of classic signal processors sound gratifyingly close to the real thing, and I feel they justify the additional expense over more run‑of‑the‑mill effects pedals.

Memories Are Made Of This

Neither of the Modeler pedals offers many user patch locations. To keep things simple, user patch selection is strictly by using one footswitch per patch, and in the case of the Delay Modeler one of the four switches allows 'tap tempo' input of delay time, which leaves only three other switches to perform patch‑selection duties. The upshot is that you can only store three user effects in the Delay unit. Saving a patch is simply a case of adjusting the control knobs, then holding down one of the footswitches for three seconds. The only model which doesn't use the footswitches in this way is the Loop Sampler, because all four switches are needed to control the starting, stopping and overdubbing processes. The Modulation Modeler can store up to four user patches, as it has no tap‑tempo button.

On both pedals an LED next to the relevant footswitch shows which memory is active, and pressing a switch that has its LED illuminated momentarily bypasses the effect. By default the bypass is a hardwired relay‑controlled one, which means that any on‑going delays are killed as soon as you engage the bypass. However, you can change this state of affairs by holding down two buttons while powering up, so that the bypass is purely electronic. The advantage is that delays will then continue to their natural conclusion.

When the optional pedal is in use the two extremes of the pedal correspond to two different sets of knob positions. A simple routine is used to memorise the two sets of positions, and this information is saved along with the patch. Any or all of the knobs, with the exception of the model selection knob, can be assigned to pedal control. Delay time, feedback, modulation rate or modulation depth, for example, could be changed in real time using this feature.

The Making Of A Model

Line 6 developed the Modeler units in a similar way to their POD modelling guitar preamp (reviewed February 1999). A number of well‑known vintage processors were analysed, then their features and foibles were modelled as closely as possible, using DSP technology. In the case of the Delay Modeler this meant looking at different tape, analogue and digital echo boxes, then trying to recreate such artifacts as wow and flutter, distortion and high‑end loss in the feedback path, tape saturation, and so on. The result is a choice of echo simulations that all sound very different to each other and provide close approximations of the equipment they purport to emulate. The Modulation Modeler takes a similar approach to Leslie cabinets, phaser and flanger pedals, tremolos, panners, and so on, though in many cases the range of adjustment is greater than that provided by the vintage original. Even the much‑coveted Roland Dimension D (which alone costs significantly more than this pedal) is 'cloned'.


  • Simple‑to‑use pedal format.
  • Quiet 24‑bit signal path.
  • Excellent emulations of classic processors, especially the tape delays.


  • No supplied PSU.
  • Limited user memories.


Once again Line 6 have shown that physical modelling can be used to recreate the tonal essentials of classic analogue circuitry without the noise or cost.