Post your questions about the Claravox Centennial here

Posted: 10/30/2020 3:59:01 PM

From: Sammamish, Washington

Joined: 2/13/2005

Moog has confirmed they've received all the questions and extends their thanks! Will post back once we have their reply.

Posted: 11/16/2020 10:40:14 PM

From: Sammamish, Washington

Joined: 2/13/2005

Just a quick follow-up... I've sent an email to Moog to ask for an update on the questions. Hopefully we'll hear back soon. 

Posted: 11/17/2020 5:30:44 PM

From: Sammamish, Washington

Joined: 2/13/2005

Great news everyone - Moog has replied with an answer to all the questions! I'll try posting the full response here, and if the forums app causes problems for the formatting, I can try making a PDF of the responses available too.


How long will they be available to order?
We are excited to release this instrument in celebration of the 100 year anniversary of the theremin, and like all Moog instruments, Claravox Centennial is built with love at the Moog Factory in Asheville, NC. Our goal has always been to release Claravox Centennial to celebrate Lev Termen, Clara Rockmore, and the Theremin at this important centennial milestone. To ensure this moment in time is properly marked, we intend to limit orders to the time frame that best reflects 100 years of Theremin. Orders started in October 2020 and continue into the new year. Although we do not have a specific "last orders" date, we anticipate it to happen in early 2021.

How long will service and parts be available?  Will a service manual be published?
Moog will provide support and continue to stock service parts for the lifetime of Claravox Centennial. Service manuals are not available publicly, but all Moog Service Centers will have everything needed to support you.

When will we be able to download the user's manual?
A PDF of the user’s manual will be uploaded to when complete. We expect this to be late November/early December when layout is complete.

Will a regular mic stand work?
Yes, any mic stand with a standard thread will work. The bottom of the Claravox has an adapter that allows you to quickly attach the adapter to a standard Mic Stand and then attach Claravox to the adapter with large thumb screws which makes it much easier to take on and off (no more “spinning” the theremin around the mic stand!). You will want to check the height of your stand against your own playing height. The shape of Claravox adds about 12” of height between the top of the stand and the antennas. The matching Claravox Stand (optional) is designed with this height consideration in mind.

Are there review units out?  When will we see reviews?
Review units will be distributed next month (December).

Is the power supply a special product, or is it a relatively standard item?
Claravox comes with a specific power supply for the product.

Is the instrument grounded through the power supply or the audio out?
The Claravox power-supply is grounded.  Additionally, the instrument is grounded via the audio out.  There is circuitry embedded in the audio ground output to further isolate the audio from possible ground noise and interference.

Which Moog BBD is the delay on the Claravox based on?
The Analog BBD Delay circuit in the Claravox is a decendent of Bob’s MF104 design and also shares many similarities to the Series 500 Delay and the Matriarch delay.

Does the MIDI implementation use continuous pitch bend signals, or does it incorporate standard note on:off?
For Pitch output via MIDI, there will be a number of options:  there will be continuous pitch (both quantized or unquantized) as well as MIDI NOTE ON/OFF similar to the Ethervox implementation.


Does MIDI work in both analog and digital modes?  Will it send MIDI CC in digital mode?
Yes, MIDI works in both TRADITIONAL and MODERN modes.  However, there are a number of features that are only available in MODERN mode, so of course, those MIDI CC’s are only applicable when playing in MODERN mode. 

What resolution is the DAC?
The only DAC in the instrument is the Audio DAC used to generate the audio in MODERN mode.  This is a high-quality 24-bit AKM Audio DAC. 

Are the scales customizable? Can the scales use microtones or non-western scales?
Yes, the scales can be microtonal and there will be a handful of musically flexible scales selectable from the hardware – with a large collection of additional western and non-western scales available via MIDI message or the Claravox Software. As of now, we have not implemented the ability to define customizable scales.

Do the CV outputs only send cv, or can you send trigger or gate signals as well?
Pitch CV Output is always based on the state of the Pitch and is based on 1V/Octave scaling.  It can be quantized or continuous where the quantization amount corresponds to the settings of your TIMBRE.

Volume CV Output can be continuous voltage based on the Volume amplitude.  There will be a GATE out option for this CV as well.

Is CV -5/+5, or positive range voltages only?
There are three CV output modes:  Bipolar (-5V to +5V),  Unipolar (0V to +10V),   Unipolar (0V to +5V) 

How hot is the output audio signal?
Claravox has been designed to output a studio level of +4dBu (or ~3.5Vpp) 

It seems a shame for all the technology developed for the Claravox Centennial to be a one-off - is any of it going to be folded into a professional theremin line going forward?
Bob’s love of the Theremin and his dedication to the instrument is a legacy that Moog is deeply committed to – everything we develop derives from his legacy (and Lev’s!).  We will continue to develop new Theremins and excited to continue to work with the Theremin community.

Geometry: rod length, diameter, frequencies rf, distance pitch rod to box to volume loop.
Pitch antenna length:  16” 
Antenna Diameter: 3/8”, 
Pitch Frequency ~320KHz,
Volume Frequency ~515KHz,
Pitch Antenna to Center of Instrument:  12”
Pitch Antenna to Center of Volume Loop:  25.5”
Antennas are very similar in geometry to the Etherwave Pro

Sound samples pure without any filtering effects, vibrato and digital post production, what also can be made with common pedals, and so on. 
Gregoire Blanc has recorded some very nice sound samples covering pure to extended sounds: 

How is the warm up time and pitch stability in case of outer temperature changes, and so on?
WARM-UP Time:  We measured the warm-up time of three Theremins – Etherwave, Etherwave Pro, and Claravox and all perform similarly.  In about 10 minutes, your instrument is already very stable, but it takes about 20 minutes for the instruments to close to it’s final stasis.   This also depends on the start-up conditions of the instrument.  You will see in the graph below, on one cold startup, the Claravox had very little frequency deviation (light blue) and on another, it had a much more dramatic swing over the first 5 minutes dark blue):


PITCH Stability:  Special care was spent on the Claravox oscillator design to improve pitch stability.  Improvements were made to the oscillator design to minimize the effects of temperature on the oscillators both by changing circuit topology as well as component selection.  Claravox is highly stable as shown in the diagram below comparing the heterodyne output normalized for the Etherwave, Etherwave Pro and Claravox over an hour period.  Claravox is the dark purple plot.


Why is the Claravox opened to up to pre-order with an uncharacteristic absence of technical information or even I/O specifications?
Technical specs are available at and on your favorite Moog dealer’s website. Claravox Centennial has 3x ¼" audio outputs (Main Out, Headphone Out, Tuner Out), 4x CV jacks (2 in, 2 out), and MIDI In, Out, and USB. If you have further questions about I/O specifications please feel free to reach out at 

Is built-in pitch preview truly absent as it appears to be on this professionally-priced theremin, or can the headphone jack and volume be set up for this by reconfiguring an internal jumper as is done on the Etherwave Plus?
There are multiple ways to achieve Pitch Preview on the Claravox:

- The TUNER output is pre-VCA and pre-Waveshaper so it is always a very pure signal (i.e. not many harmonics).  This output can be used to preview your pitch.  Earbuds, or In-Ear Monitors with gain control can be connected to this output so that you can preview your pitch.  (of course, this output could also be sent to a mixer or other device).[/li]
- The HEADPHONE output is pre-MUTE (but post VCA, Waveshaper, Delay) allowing you to preview your sound as it will be heard from the MAIN output.  The front-panel MUTE switch can be used but of course, this requires your hand.  To facilitate hands free operation, a rear-panel footswitch input is provided so that you can use a standard SUSTAIN-PEDAL to mute your output and preview your pitch via the HEADPHONE output.  The HEADPHONE output has it’s own dedicated volume control. [/li]

What is the general system architecture? A block diagram would speak volumes, but even a verbal description would help. In particular, would it be fair to guess that this uses analog oscillators, digitally shaped and heterodyned and from that point passed down either an analog processing chain (traditional) or a digital processing path (Modern)?
Your guesses are quite good!  But here are the details… 

In TRADITIONAL mode, you have a fully traditional Theremin in its simplest form as shown in the diagram below:

The variable pitch oscillator is an improved version of the Etherwave Pro and the Mixer topology is very similar to the Etherwave Pro as well.  The Hetereodyne filter is an improved active filter to ensure a much purer output of the difference frequency and better interference immunity.  The Waveshaper is based very closely on the Etherwave Pro topology except that in the Claravox we are able to have digital recall over the control voltages allowing artists to save and restore their own TIMBRES on the instrument. The Volume oscillator has a traditional diode rectifier circuit that is highly filtered to fully isolate the DC component but also allow for very quick dynamic response which is used to modify a very high-SNR voltage-controlled amplifier (VCA).  As such, the Claravox has a very large dynamic range and low-noise floor allowing for both very pure sonics but also a large range of dynamic response for different playing styles.



In MODERN mode, the heterodyne filter output is fed into the digital processing block (area in gray).  There are two outputs:  OSC1 is fed directly back into the analog Waveshaper – so you have an audio path that is closely equivalent to TRADITIONAL mode as possible.  Indeed, if you make OSC1 the same waveshape (default) as the heterodyne filter, the sound of Claravox is virtually indistinguishable in both modes.  The second output of the processing block has a combination of a separate oscillator and a white-noise generator fed into a mixer.  What is not shown in this block is that there is a state-variable filter with resonance on the output of this filter.

So, you have two audio sources going into the analog VCA: OSC1 which allows a variety of waveforms to go through the full analog waveshaping process and OSC2 which bypasses the waveshaper.

What is not shown on this diagram is that the AUDIO OUT signal then goes through the analog delay section with a WET/DRY mixer. You might ask, why does OSC2 bypass the analog Waveshaper?  Here was the design thinking….  Bob’s analog waveshaper is a beautiful circuit design to sculpt the distorted triangle coming out of the heterodyne filter and provide a range of sounds that span a theremin vocabulary.  As such, it is not appropriate for all types of waveforms.  Having OSC2 allows you to mix in a completely different set of sounds to further extend that vocabulary if desired.  I.e. to have the best of both worlds!

Does the pitch arm contain active electronics within or is it similar to the EW Pro with only passives?
The pitch arm only contains passive components – a custom-design 3-Pi coil is used for impedance matching.

Can the analog portion operate independently of the digital side?  Thirty years from now when the digital side (I mean programmed devices, not discrete logic) is long since obsolete and parts are no longer available will it be possible to still have a partially functional/restorable analog theremin (asking for some future owner).  
Moog designs it’s instruments to last a life-time.  Any of the components (analog or digital) can become obsolete but Moog keeps service stock of parts to support your products.

I'll repeat one of my other first questions that I posed prior to ordering: what are the MIDI capabilities?  Does it send processed note, bend, volume etc. information for running a midi synth, or are the MIDI I/O functions limited to managing preset loading/storage or other control functions?
The Claravox has a full set of MIDI implementation from control in/out (TIMBRE settings, Instrument State), Pitch Control settings (Octave, Scale, Root, Quantize), to Pitch and Volume continuous signals as well as Note On/Off messages, time synchronization for analog delay taps, pitch and volume tracking parameters, as well as instrument global settings.  These are both implemented in MIDI CC and NRPN messages.

A full MIDI specification will be available soon with the Claravox Centennial Manual PDF that will go up on in the coming weeks.

Is there any real-time MIDI control for effects on the digital side?
For sound design, there is MIDI control for all settings (wave, brightness, filter, delay amount, etc.) that are common to both TRADITIONAL and MODERN modes.  In MODERN modes, there is full MIDI implementation for all of the additional sonic capabilities of the instrument – oscillator waveforms, levels, noise level, state-variable filter, etc.

All aspects of the instrument can be controlled via MIDI enabling you to synchronize sound, for example, to an Ableton track, synchronize the analog delay time to a tempo-based piece, or even have arpeggio / sequencer type motion on the Claravox by sending it note transposition messages.

Additionally, Claravox comes with a fully realized software package that will be available initially for iOS devices and shortly thereafter, for OSX and ultimately Windows so that the full instrument is actualized in a cohesive way.  So, for example, one could envision a performance mode, where an iPad is connected remotely to the Claravox via a Bluetooth MIDI interface (such as the CME WIDI master) making the full range of the instrument immediately and intuitively available.

Is the analog portion (traditional) based on the Etherwave Pro's design?  I don't think anyone expects it to be identical, but the obvious similarity with the register switching, timbre settings, and in fact the sound (based on the demo) is making some of us hopeful that this is indeed the case.
In many ways, yes!  As discussed above, the pitch and volume oscillators hold a lot of similarity to the Etherwave Pro with improvements.  The heterodyne architecture is very close to the Etherwave Pro but the heterodyne filter was upgraded to an active filter to get a much purer difference signal and increase noise-immunity.

The analog Waveshaper is based completely on the Etherwave Pro as this was a piece of Bob’s work that we wanted to preserve.  Please note that this is available both in TRADITIONAL and MODERN mode.  So sonically, the instrument can sound identical in both modes.

Similarly, the Analog Delay is based on our classic analog delay circuits and identical in both modes.

Here are some differences, though:
- unlike the Etherwave Pro where the TIMBRES are hard-wired, the TIMBREs in Claravox are all voltage-controlled which allow you to customize the TIMBRE sets easily while playing the instrument.  Additionally, the software allows you to create a large library of TIMBREs and easily download them down onto the instrument.
- In the Etherwave PRO, the PITCH and VOLUME response are done at the analog level. In Claravox, in TRADITIONAL mode, we do no response modification but just provide the direct theremin response of the instrument like an early theremin. However, in MODERN mode, both PITCH RESPONSE (linearity) and VOLUME RESPONSE (dynamic curves) are available and adjustable from the front panel.

Does the Claravox have any ESD protection on the antennas?
Yes, all inputs and outputs on the Claravox are fully ESD protected and are rigorously tested both at Moog, but more importantly by an independent testing lab.  This is actually a requirement for CE certification and is true of all of our instruments!

I'm guessing that since this is probably categorized as a low voltage device which uses an external power supply that is pre-approved by UL or ETL, is it even subject to any UL/ETL safety requirements that would have imposed an ESD testing requirement? Or for that matter are there any FCC emission or susceptibility requirements or approvals needed or granted for this theremin?
Like all of our instruments, Claravox has to conform to all emission/susceptibility and safety requirements of FCC and CE.  This is done by independent testing labs and we rigorously test all aspects of our designs during the development process.  Typically, we send the instrument multiple times to the testing lab during the process to ensure that we are conforming to international standards.

What's the peak-to-peak voltage swing on each antenna?
PITCH is typically ~35Vpp and VOLUME is typically ~28Vpp

What's the minimum gestural bandwidth / maximum rise time on each axis (hand gesture => sound change)?
I think you are asking how responsive each axis is.  This is hard to quantify specifically but the goal of Claravox was to provide a response that is significantly faster than human gestures.

On the Volume , Claravox was designed to improve the typical response time and also have better signal rejection above the response frequencies (so that the signal itself is quieter and stable) as well as improved immunity from pitch antenna interference.  The design was changed to accommodate this.  The analog response time of the volume circuit is in the low 2-3msec range which is much faster than typical instruments.

The Pitch response is purely based on the physical motion, there is no intrinsic response lag as the heterodyne filter is very steep and set at 25KHz (40 usec).

Now in MODERN mode, there are obviously features that require digital control algorithms, but here Claravox is designed to be as fully responsive to gestures as in TRADITIONAL mode.  Some geeky numbers:

The volume processing happens in 50 usec intervals (or 20KHz).  This is close to two orders of magnitude faster than the quickest gestural motion of a hand.  Again, Claravox was designed to have exceptional volume responsivity and sensitivity to accommodate both large, classical expression and very quick, short percussive expression.

Likewise, the pitch sampling is also happening at those frequencies, so the sampling latency is well beyond the limits of gestural resolution.  You may ask “How can this be possible given the audio frequency range?”  I can’t answer this question except that we figured out a very effective way to do this and it works.

So the goal of the Claravox was to provide as responsive and transparent instrument in both TRADITIONAL and MODERN modes to that you feel 100% connected to the instrument.

Does the pitch side use a series EQ inductor to improve linearity?
I am not sure exactly what you are referring to but I will assume you mean the coil between the antenna and the oscillator.  Yes, absolutely!  We have a custom 3-Pi inductor wound for Claravox to match the antenna impedance with the L-C tank impedance.

Is there any mathematical / algorithmic / software processing being applied to improve pitch field linearity?
In TRADITIONAL mode, no.  The heterodyne filter output goes directly through the VCA and out to your ears.  In MODERN mode, yes – there is a variable curve that you can adjust from the front panel (or software) called PITCH RESPONSE that allows you to adjust this curve to match your playing style.  So far, our artists have been able to find a very linear response out of the instrument using the initial curves.  We hope to work further with artists to evolve these curves.

Is MIDI an integral part of the internal processing signal path (axes => midi out => midi in => synth) or is there a more direct and lower latency connection between the axes and the sound synth?
No, MIDI has nothing to do with any audio or processing signal path.  This is essential to the effectiveness of the instrument.  As mentioned above, Claravox is designed to be transparent in terms of signal processing and the numbers presented should show that.  Maximum processing latency is 200usec.

So you can envision it this way…  When in TRADITIONAL mode you are listening directly to the heterodyne output.  In MODERN mode, you replace that heterodyne output by the processed audio.  The processed audio introduces no perceived latency due to the way the instrument is designed.

MIDI is only employed to communicate externally to other devices.

Is the volume axis processing digital, or does it have a 100% analog mode?
In TRADITIONAL mode, the rectifier output is scaled, filtered and directly fed into the VCA – i.e. 100% analog.  There are actually ways to tailor this response even further in the analog path, but that is deep under the hood!

In MODERN mode, the rectifier output is sampled at 20KHz, processed at 20KHz and then transformed to an analog signal at 20KHz that feeds into the same VCA.  So while it has a digital processing step, it is happening at such a high rate that the effect is indiscernible.

Remember that traditional theremin’s have quite a slow volume response due to the rectifier filters – the design intent of Claravox is to be more responsive in both MODES.

What is the function of the expression pedal input?
The CV IN (expression pedal) input can accept either a traditional ring-powered expression pedal, or any active control-voltage (i.e. connectivity to other analog instruments and CV devices).  The input voltage range and offset can be set via the Claravox Centennial Software.

The default configuration for the input CV is to modulate the FILTER of the Waveshaper, but like most of our synthesizers, this CV can be routed and scaled to a host of internal control voltages and/or parameters.  There will be a “modulation matrix” available via the Claravox Centennial Software. The matrix gives Claravox Centennial another level of expressivity via CV IN: modulating DELAY TIME, AMOUNT, WAVE (to get PWM like effects), NOISE level in MODERN mode, etc. etc.

Additionally, it should be noted that the rear-panel footswitch input will default to MUTE to be able to be routed to a few other destinations as well, the most obvious being the TAP TEMPO input to the analog delay.

Posted: 11/17/2020 5:58:19 PM

From: Minnesota USA

Joined: 11/27/2015

I have to give a lot of credit for these responses.  When re-reading a question I would think "no way are they going to touch this", and yet they did!
There is actually a lot of detailed information here that I did not expect (block diagrams!!!), and you can tell that they are excited and proud to talk about it.  It turns out that this is even more than I had hoped for when I placed the order, so this is all good news.

Thanks to Jason and the folks at Moog for putting this together!

Posted: 11/17/2020 6:05:48 PM

From: Sammamish, Washington

Joined: 2/13/2005

Agreed! The degree of detail and transparency in these responses is amazing! Thanks to Moog!!!

Posted: 11/17/2020 7:03:02 PM

Joined: 11/4/2020

I had a Theremini and was never able to get it to control my synth properly via CV - Looking at the MIDI details above it looks like the Claravox will. Not sure whether MIDI signals will also be transmitted via the USB output tho but assume they will. 

I'm glad I placed an order. The Claravox is looking better than I hoped. I really appreciate the detailed answers provided by Moog

I had emailed Moog about the windows application and they had replied that it will be available when the Claravox is released although reading the above it looks a bit more vague than that. I'm hoping that by the time mine gets to NZ it will be available

Posted: 11/17/2020 8:06:49 PM

From: Berlin Germany

Joined: 4/27/2016

These detailed answers are far more than might be expected. Perhaps the Moog developers also benefit from the diverse discussions and findings from the forum?

I'm particularly interested in the analog part and now have other benchmarks for my own stuff (warm up, pitch stability, geometry, frequencies). 

The ask about pure sound (without all artistical and technical forming) is answered with the playlist by Gregoire Blanc, who would turn most rotten theremins into wunderful sound-events.   

Posted: 11/18/2020 9:31:53 PM

Joined: 11/12/2020


Wow, this is a lot of stuff and sounds quite encouraging!
The diagram of the oscillators temperature behavior comparison ‘Pitch drift with power startup’ seems to show three Claravox Theremin instruments, each equipped with an other type (temperature coefficient) of tank 2200pF COG capacitor applied; ‘Clara: 2200pF COG PSU TDK’ seems the best. Why do they denote them ‘Bench’ / ‘PSU’ = Power Supply Unit / ‘TDK’ = (EPCOS) Manufacturer of Electronic Components ?
Do they apply switching regulators within the internal power supply which need temperature compensation of the voltage drift affecting the pitch oscillators – meaning there are no additional linear regulators applied to supply the oscillator circuits (including the tuning voltage)?

Posted: 11/19/2020 2:53:31 AM

Joined: 10/24/2020

I think they are 3 tests on different power supplies. My guess is that the "bench" is with their bench power supply, the "PSU" is the unit that will ship with the Cvox, and the "TDK" probably refers to a TDK Lambda power supply. They make famously stable supplies (both switching and linear) used for delicate and/or noise sensitive electronic instruments (I used to have one for a microscopic grain holography unit)

I think that it is an interesting clue for us DIY types that the stability of the PSU can directly affect the pitch drift. It makes a ton of sense, I just never thought about the differences between my test supply and the cheap switching power supplies I usually plug into stuff. Puts a fire under my ass to build up all the parts I bought for my own diy hq toroidal power supplies that is sitting over in the corner!

I don't actually have a ton of issues with pitch drift at home, as I tend to leave my 'min on but muted when I'm not playing. 

I'm so stoked to get my Cvox now. I wish I knew when it would arrive, so I could book a week off work!

Posted: 11/21/2020 10:50:47 AM

Joined: 11/12/2020


I think Flounderguts is right with the different power supplies. I‘ve not thought about that because a theremin‘s oscillators should not interact with the drift of the external wall wart (or whatever is used to supply the instrument). There have to be extra means for providing a stable supply voltage to the oscillators (which of course should be designed to drift as little as possible with supply voltage).

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