Looping with the Lexicon MPX G2
Looping with the Lexicon MPX G2
There are actually several ways to loop audio in the Lexicon MPX G2. All looping on the G2 is done using effects in the Delay block. Like it's sister product, the MPX 1, the MPX G2 contains several different delay effects that can be configured to do some pretty amazing looping. With the exception of the new JamMan effect and more audio memory, the MPX G2 is almost identical to the MPX 1. Since my MPX 1 Looping page covers most of the standard delay stuff, I'll stick to the features that are unique to the MPX G2 here.

The "JamMan" Delay Effect

Though the MPX G2 doesn't provide the level of looping support that Lexicon's original JamMan did, the feature is still pretty amazing considering it's built into the basic product. Probably the most significant difference between the original JamMan and the JamMan effect in the MPX G2 is that the G2 JamMan only supports a single loop. On the original JamMan, you could sequentially record and later select from up to 8 separate loops. We had intended to support this on the G2 but ran out of time and had to ship the box without this feature.

Like the original JamMan, recording is initiated by the press of the Tap button then stopped by a second Tap button press. The Tap "event" can be generated the front panel button, a foot switch connected to the G2 rear panel, a MIDI Continuous Controller message or from several other more obscure sources as decribed below.

TAP via MIDI Continuous Controller

On the MPX G2 Continuous Controller #119 is hardwired to the Tap function. Lexicon's MPX R1 remote in fact uses this controller to send a Tap command to the MPX G2. Though there are other ways of sending a Tap command via MIDI Controller, #119 was tweaked in the MPX G2 software to be detected faster than the others so it is the preferred one to use.

TAP via Rear Panel Foot Switches

Another common method of Tapping in a JamMan loop on the MPX G2 is via a foot switch connected to the rear panel jacks. These are configured from the EDIT: Tempo menu's "Tap Source" parameter.

Important Note: The "Tap Source" parameter is not enabled until a different parameter is selected on the MPx G2's front panel interface (simply pressing the '<' key for instance). This was done to prevent virtually hanging the system when scrolling past the LFOs that appear on the list of sources.

TAP via Other Sources

A variety of other control sources can be used to generate a Tap event on the MPX G2. As with the rear panel foot switches, these are selected from the EDIT: Tempo menu's "Tap Source" parameter. This is a list of virtually all of the control sources available in the system including both internal and external sources. External sources include the foot switches, the pedal and MIDI. Internal sources include the A/B generator, the LFOs, the random number generator and the envelope generator.

A good example of a somewhat obscure loop control senerio would be using the envelope generator (Env) as the Tap Source. Now you could trigger the beginning of a loop record based on signal level. Play a loud note when you want to start and end the loop. (Note that to do this you need to set the source of the Envelope generator in the EDIT: Controllers "Env" menu. If you set both Envelope sources for the main input you get a better signal.

MIDI Clock

As with the original JamMan, MIDI clock is one of my favorite aspects of the using the JamMan. The MIDI clock support allows you to synchronize the loop to to an incoming MIDI clock (from a drum machine or sequencer) or to generate MIDI clock so the drum machine and/or sequence can slave to the G2.

The real trick to making this work is only briefly mentioned in the MPX G2 users guide but is vitally important. As with the original JamMan, you have to tell the system how many beats will be in your loop. The original JamMan did this from it's front panel rotary encoder but the on the G2 you set this from the "Beat Value" in the EDIT: Temp menu. It seems a little weird but this was the best way to integrate the JamMan loop timing into the rest of the system (more on this below).

The Beat Value parameter basically defines the musical time reference that is applied to successive presses of the Tap button. The first few selections of the Beat Value parameter are things like Quarter Note, Half Note, etc.. which are useful values if you are tapping those intervals. When tapping in loops however, the period of time defined by tap presses is multiple beats. When you adjust the Beat Value parameter you'll notice that after Dotted Quarter the parameter jumps to 2 beats followed by 3, etc.. If you wanted to create a loop that was two measures long in 4/4 time, you would select 8 beats. With this set, you'll notice that the loop perfectly synchronizes to drum machines and sequencers in 4/4. Obviously other time signatures can be supported as well.

When the EDIT: Tempo "Source" parameter is set for "MIDI" and the G2 detects incoming MIDI clock; it measures the distance between the clocks and derives it's tempo. When the Tap button is pressed, the system goes into record then automatically exits when 8 beats (or however many were selected) worth of MIDI clocks have been received. A second press of the Tap button is not required and in fact should not be made.

When the EDIT: Tempo "Source" parameter is set for "Internal" you are defining the loop size by successive presses of the Tap button: the first press starts the recording, the second one ends it. As soon as you press Tap the second time, the MPX G2 outputs a MIDI Start message then begins outputting MIDI Clocks perfectly synced to the loop. The MIDI Start message tells any connected sequencers or drum machines to begin playing. A MIDI Stop message is sent when the loop is "Cleared" (one of the parameters of the JamMan effect). (The "Controlling the JamMan Effect Using Program Change Messages" section describes how to clear a loop using MIDI Program Change messages).

There are advantages and disadvantages to internally generating MIDI clock by tapping in the loop size and slaving to an external device with a fixed tempo. When you have a tune that you always want to play at a specific tempo, it's probably a good idea to slave the MPX G2 to incoming MIDI clock (EDIT: Tempo "Source" set for MIDI). If you want to define the tempo of the tune in real time, set the Source for "Internal" and slave the drum machine to the G2.

Any kind of MIDI clock is a relatively coarse timing reference (certainly compared to digital audio) and contains a certain amount of jitter. For this reason, slaving the MPX G2 to external MIDI clock can produce slight anomalies at the loop edge. If the clock jitter makes the loop slightly longer than it was when it was initially created, a little bit of the loop gets cut off. Unfortunately the G2 doesn't have enough DSP resources to really clean this stuff up so you typically need to either mask the noise or try not to play at the loop edge. One trick is to place a strong musical event in the sequence at this point to mask out the noise. Unfortunately there's really not much else that can be done to help the situation.

For the cleanest loop edges, set the EDIT: Tempo "Source" parameter for Internal and tap in the loop size in real time. Now all of the timing is generated internally and precision is retained.

Synchronizing Other Effects To The JamMan Loop

Because the synchronization of the MIDI clocks to the loop is handled by the EDIT: Tempo "Beat Value" parameter, all of the timing in the system is automatically locked to the JamMan's loop size. If for example you set one of the LFOs Rate parameter for "cycles per beat" (the OPTION of the Rate parameter), the LFO cycles will be perfectly matched to the loop. This goes for virtually all Rate parameters including choruses and flanges. There is potential for some pretty amazing stuff here. Well worth checking out and messing around with.

Nondestructive Click Track

Another of the last minute features that was added to the MPX G2 was a non destructive Click effect that is available in both the Effect 1 and Effect 2 blocks. When the JamMan effect is selected, the Click effects output an audible click on the beat synchronized to the loop. Mix and Level parameters are provided and, like all effects, the click can be routed into other effects or directly out of the system for an audible trigger.

One use of this would be to route the click to the left output of the box feeding the stage monitors with click-less right channel going to the mains. Now you have a reference to the click without the audience hearing it. The click can also become an instrument of its own by feeding into the reverb and/or other effects (EQ, chorus, etc..).

Controlling the JamMan Effect Via Program Change Messages

One of the lesser known features of the MPX G2 is it's MIDI Maps subsystem. Normally MIDI Maps allow you to change the assignment of buttons on your MIDI foot controller to programs in the G2 (i.e. Remote button 1 selects MPX G2 program 59, etc.. ), but on the MPX G2 the MIDI Maps were extended to include other types of control. Using MIDI Maps you can for instance, toggle the JamMan loop in and out of the Layer mode using a program change message from your foot controller. Normally you would need to set up a Patch from a MIDI Continuous Controller to the JamMan "Layer" parameter to do this but the extended MIDI Maps allows this kind of control without wasting a Patch (or going through the aggravation of setting one up).

My MPX G2 MIDI Maps page describes editing and using the maps in detail but the basic procedure for configuring them is pretty straight forward: select a "Pgm#" and associate a G2 program to it (from the SYSTEM: MIDI Pgm Maps menu). The G2 even includes a Learn mode that allows you to just press buttons on your remote to select the MIDI Program Change number then select MPX G2 programs and functions to map to it from the G2 front panel.

If you scroll through the available MPX G2 programs, you'll notice some non-program items at the end of the list. These include "Clear Loop", "Layer", "Replace", "Delay", Start Stop", "Tap", "Bypass" and bypasses for each of the effect blocks. All of these things can be mapped to program change numbers making them available via simple program change messages.

Once a MIDI Map is set up, it is enabled from the PROGRAM mode by pressing the OPTIONS button and selecting "Show members of MIDI Maps". When you press the OPTIONS button to return to the PROGRAM mode, pressing the '<' and '>' button selects a particular MIDI Map. I've found I never use more than one map but in different situations, different MIDI Maps may be more appropriate than others.

One of my favorite ways of using this feature is to set up a MIDI Map for the MPX R1 remote (from Lexicon) which allows selection of 5 MPX G2 programs on the top 5 buttons and control of the JamMan effect on the bottom 5 buttons. I make sure the 5 programs on the top buttons all contain the JamMan effect and use the bottom buttons to manipulate the loops I create. Typically button 1 would be assigned to Clear the loop, button 2 to toggle in and out of Layer, button 3 to toggle in and out of Replace, button 4 to toggle in and out of Delay mode and button 5 to start and stop the loop. Very easy to set up and use yet extremely powerful.

If you have any questions on using the JamMan feature on the MPX G2 or have suggestions of content to add to this page, contact me at my Suggestions page.

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