Your Meta Companion
to the Music Easel.

Now with more better meta.


The Model 416 Meta Expander is a fully-fledged, standalone breakout box for the BEMI/BUSA Music Easel, which provides access to all of the Easel- and Program Card's patch points (effectively doubling the Easel's control voltage possibilities), and greatly extends the Easel's capabilities with useful, built-in modules.

Version 2 is available as either a "full option" build into its own boat, or as a "panel only" version which can be build into exisiting 4U Buchla boats- or cabinets.

The Model 416 Meta Expander communicates bi-directionally with the Easel by means of a custom-designed Edge Card and a 60-pin flat ribbon cable assembly.

A first prototype of a breakout box was developed in early 2014, right after BEMI's new Easel became available. Several iterations and a 2nd Easel later, I developed a one-off Twin Expander -- aptly named the Model 844 Expander (note the willful 208x4 error). After getting quite a few requests from fellow Weaselers, and realizing that it might be a better idea to limit a commercial version of the Expander to a one-Easel configuration, I designed the Model 416 Meta Expander V1, and brought it to market at the end of 2017. This was a one-run-only, build to order project. The last one left July 2018.

Since then I've gotten some more requests, so in August 2019 I decided to design a new version. Rebuilt from the ground-up and adding new features, it took more than half a year to finish. And then -- ready to be released on the 1st of March 2020 -- something weird happened to the planet...

Nevertheless, it's now August 2020, and Version 2 is here.

Read on...
{Last update : 11 Sept 2020}

Sound & Vision

Some Meta patches.

Demonstrating a few of the 416's possibilities.
With a surprise ending.

Main Features

Easel Patchpoint Doubler

• The bottom section of the 416 doubles up on the Easel 208's main patchpoints, so now you can modulate Pitch, Timbre, Period, et al with at least two sources simultaneously.
• Extra patch points not directly accessible on the Easel's patch panel, with adjustable voltage control over the Envelope parameters & COM Waveshape.
• Access to Random Voltages 3 & 4.
• Trigger inputs for the Sequencer, Envelope, Pulser & RVs.
• Pulse outputs for the Sequencer's individual as well as selected steps, Pulser, and Keyb Pulse.
• Full voltage control over most of the Easel switches.

Additional Modules

• Two fast Comparators with threshold control, for pulse generation. Comp A accepts TiniJax or banana inputs, while Comp B can have minijack or nana inputs. Comp A also generates a 5V Gate. A combo output (A+B) is also available.
Slope Generator based on Serge's DSG, Buchla-fied.
Sample & Hold module, with internal VC Clock which is  available at a separate output.
Envelope Generator, switchable between AR and AD.
• 3-ch Mixer (DC-coupled) with attenuators. Chan 2 can add gain (x1.3), while Chan 3 has a bipolar control and individual output.
White & Pink Noise, available on both banana- and TiniJax.
• Passive OR-mixer; accepts pulses & CV's.
Sequencer Transpose
Manual Gate button & output (5V).
• Jack translator (Banana/Minijack/TiniJax).

Delivery Options

"V2's biggest new feature is its ability to be build into existing cabinets."


Model 416 Standalone version

This is the full option version, ideally suited for use with an Easel suitcase or similar housing. Its (frontal) height perfectly matches the edge of the suitcase, and its 22.5º inclination on the support makes it ergonomically very practical to use.
The boat and support have special non-slip feet, so the whole system won't budge, even when patching.

Model 416 Standalone with Easel

In the box :
• Model 416 V2
• Modified 4U Buchla-compatible boat (by SaModular)
• Cable Assembly (15cm/±6in)
• Two Edge Cards: w/ Sullins connector & lo-profile
• 3D-printed custom Support (by CoverUp)
• Extensive printed User Manual

Model 416 PANEL

Model 416 Panel version

The panel version is meant to be build into existing 4U (or 6U) Buchla-compatible cabinets or boats. {Your} boat needs to be slightly modified -- removing or folding the mounting lip where the cable assembly comes through -- so that the flat cable does not get squeezed. How to is explained in the User Manual.

Depth [behind panel, and with cable assembly installed] is a skiff-friendly 4cm (1.6in).

Model 416 Panel backside

In the box :
• Model 416 V2
• Cable Assembly (15cm/±6in)
• Two Edge Cards: w/ Sullins connector & lo-profile
• Extensive printed User Manual

Model 416 Edge Card(s)

The Expander comes with two interchangeable Edge Cards.

Edge Card Expandable



This Edge Card has an extra Sullins connector -- the same blue one as on the Easel -- and is used when you need to use Program Cards or other external expander units.

Note however that when using other expanders simultaneously with the Model 416, chances are you'll need some sort of powered hub. Since the Model 416 is powered by the Easel and is probably already near the maximum of its supply ability, adding another expander might just bring the Easel's supply to its knees. You don't want that.

Edge Card Lo-Profile

Low Profile

This Edge Card has no extra Sullins connector, and is thus ideally suited for Weaselers whom need only the Model 416 Meta Expander. Its inserted height is a only ±1cm (0.4"), and doesn't obstruct the lower knobs & jacks of the Expander. Perfect for live gigs. 


Though developed with and for the Bemi Easel, the Model 416 Meta Expander is 100% compatible with the 208r Rev2 clone as well. Later (and other) clones have not been tested, but as long as those adhere to the EXT/PROG INTERFACE pinout (as they should!), there won't be any problems hooking up the Model 416 V2.

Rev 1 of the 208r is NOT compatible !!

The new BUSA 208C has been tested, and is 100% compatible with the Model 416 V2. However, Buchla USA recently changed one feature on its connector, so now the Seq Step 5 output will put out a steady 10V DC instead of a pulse. You can either simply ignore that output (though it won't hurt anything when accidentally patched), or disconnect the Step 5 jack (a 5-minute operation).
Apparently the latest iteration of the BUSA Easel itself (just before the 208C release) has that same ehm, feature...

Onwards from its very early development (2017), the Model 416 Meta Expander has been tested with several versions of the Easel's power supply, including the latest one. No problems were ever encountered.
Only the very first version of the Easel's power supply, as delivered over the first half year only, will introduce odd behaviour because it was underpowered and badly designed. If you [still] have one of these, please contact BUSA and ask for an updated power supply.

Notice that the 208r clones need to be in Both or Remote Mode in order for the Model 416 Meta Expander to be fully operational.
(I'm not sure if this is still the case for later clone models)


"Both the Easel and the Model 416 are very robust machines."

The COMPARATORS generate a healthy 1.8ms @ 10.2V Pulse from any signal between 0V and 13V. Comparator A simultaneously generates a 5.2V Gate, the width of which depends on the Threshold setting and the variation of the incoming signal.
Tip: use a Comparator to clean up weak- or spurious external triggers, so you can steadily trigger any Easel module.

The SLOPE GENERATOR can cycle between 11.8 seconds and 3.2KHz @ 9V (somewhat less for higher frequencies). Its End Trig output is a 80us @8.9V pulse, able to drive all Easel (and 416) modules. The full-on "Scaled CV" input is calibrated for 1.2V/Oct.

The SAMPLE & HOLD sample input is switchable between White Noise (for real random steps) or any other signal you can throw at it. Its output depends on the incoming signal (0...9.5V when fed WN). The internal VC CLOCK spits out a 4ms @ 9V pulse at its dedicated patch point (with LED). It can cycle between 7.5 seconds and 125Hz, up to 800Hz when CV-ed with 12V.

The AD/R envelope generator's behaviour can be switched between "triggered" (AD) and "gated" (AsR), and will accept any fast-rising signal above 2.6V to initiate the Attack. Its output is 9.6V, with exponential slopes. Attack time goes from 1.5ms to 4.7s, Decay time goes from 0.5ms to 7s.

The MIXER has three DC-coupled input channels, with dedicated attenuators. Ch1 is unity gain, Ch2 has a gain of 1.3, and Ch3 has a bipolar attenuator. Channel 3 has its own dedicated output, so you can use it as a signal processor of sorts. A LED will tell you when the summed signal reaches 10V (a very usable signal level for the Easel), and the output will hard-clip at appr. 14V.

White Noise signal is 0...9.3V, and Pink Noise fluctuates between 0V and an average of 8V. Both are simultaneously available at banana and TiniJax.

The passive (diode) OR-rer is often used as a Trig/Gate combiner, though you can patch literally anything to its two inputs ~  e.g. feed it an audio signal from the Slope Gen and a slow S/H output for some crazy waveform mangling fun. Note: an OR-mixer is not a summing mixer; it does things differently. Try it.

The MANUAL GATE generates a 5.2V gate as long as the momentary button is pressed. Unlike many other MG's, this one can drive a lot of sources without a reduction in gate level.

Oh, and then there's also a SEQUENCER TRANSPOSE CV input, an undocumented feature of the Easel, nowhere else to be found...

The Model 416 Meta Expander V2 comes as a build-to-order product only, and is not available as a DIY or kit solution. Except for the support stand (by CoverUp), separate items (Edge Card/ribbon assembly/etc) are not available for purchase. Never hurt to ask, though...

Pseudo-lifetime service & support is free ~ the usual caveats apply.

I cannot be held responsible for any damage done to any apparatus as a result of hooking it up to the Model 416 Meta Expander V2. Though rest assured, as long as you don't attach the ribbon assembly the wrong way round to the Edge Card or 416 Unit (which is pretty hard to do), you'll be safe & sound. ALWAYS POWER DOWN THE EASEL WHEN DIS/CONNECTING THE 416 !!

Pre-orders for the Model 416 V2 start on the 22th of August 2020, and end on the 30th of September 2020.
After that, ordering will not be possible anymore.

Direct sales only -  please order here.

Thank you for being interested in the Model 416 Meta Expander V2 !
Please stay safe.
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