Theremin 2008 Midi-deluxe | Tubular-Loop & Rod-Antenne

Posted: 4/22/2008 5:16:06 AM
MichaeliSTGT

Joined: 4/22/2008

I found this on ebay. Has anybody heard of them before? What do you think about them?

theremin on eBay... (http://cgi.ebay.de/Theremin-2008-Midi-deluxe-Tubular-Loop-Rod-Antenne_W0QQitemZ310043085380QQihZ021QQcategoryZ40732QQtcZphotoQQcmdZViewItemQQ_trksidZp1742.m153.l1262)
Posted: 4/22/2008 11:23:05 AM
Thomas Grillo

From: Jackson Mississippi

Joined: 8/13/2006

Never seen this one before. no knobs? I saw a label in the large picture that seemed to indicate automatic callibration. Really strange.
Posted: 4/22/2008 2:20:07 PM
fairplay

From: Germany, near Munich

Joined: 11/20/2007

...Gordon pointed to it a couple of weeks ago...

...Gordon?

(one of three was sold - perhaps Gordon knows more ;o)
Posted: 4/22/2008 3:15:15 PM
FredM

From: Eastleigh, Hampshire, U.K. ................................... Fred Mundell. ................................... Electronics Engineer. (Primarily Analogue) .. CV Synths 1974-1980 .. Theremin developer 2007 to present .. soon to be Developing / Trading as WaveCrafter.com . ...................................

Joined: 12/7/2007

Thierry pointed this Midi Theremin out to me http://www.thereminworld.com/forum.asp?cmd=p&T=3140&F=1&p=7
From what I can see (and understand from the translation) it looks interesting (and a bit threatening!) but has some of the same 'problems' and 'limitations' of my original ThereAsynth design.. Namely, sensing field is small, and latency is long.

Someone said that this product was PSoC (Cypress Programmable System On Chip) based, I have not seen this in anything I have read - But I am a PSoC Consultant, and my TherAsynth used the PSoC for capacitive sensing, and I have now redesigned my sensor / antenna circuits because the PSoC is not up to the job of directly/accurately sensing capacitive proximity at a distance > about 250mm
Posted: 4/22/2008 6:14:37 PM
Thierry

From: Colmar, France

Joined: 12/31/2007

That's written in the description:

"# Abtastung der Objektdistanz (Hand) über kapazitive Änderung (E-Feld-Messung) bis zu 30cm
# Einsatz von PSoC-/CapSense-Technologie
# hohe Empfindlichkeit und Selektivität (bis zu 300mm Antennenabstand)
# Touchpad zum Zurücksetzen / automatisches Kalibrieren über Sensorpad"

My poor translation:

# Sensing of the object (hand) distance via capacity variation (E field measurement) up to 30cm //=12"
# Using PSoC-/CapSense technology
# High sensitivity and selectivity (up to 300mm antenna distance) //always 12
# Touchpad for resetting / automatic calibration via sensor pad"
Posted: 4/22/2008 6:35:49 PM
FredM

From: Eastleigh, Hampshire, U.K. ................................... Fred Mundell. ................................... Electronics Engineer. (Primarily Analogue) .. CV Synths 1974-1980 .. Theremin developer 2007 to present .. soon to be Developing / Trading as WaveCrafter.com . ...................................

Joined: 12/7/2007

Thanks Thierry..

The "Capsense Technology" is the reason for the 30cm range limit - It is the obsticle I hit.. And following the discussions here, where I learned that 30cm was not going to make many Theremin users happy, the (main) reason I abandoned CapSense (and scrapped my nearly completed TherAsynth) and started my re-design which is more focussed on what (from discussions here) I believe Theremin players really want and need.

The other issue was latency - CapSense can be accurate, but the accuracy is a function of how long the samples are integrated for.. With some tricks, I was able to get good-enough accuracy at between 250 to 300mm with an update speed of 10ms (100Hz) - This is probably good enough for MIDI, particularly when note on/off protocal is employed.. but it can cause some serious problems with continuous control signals.. Glitches can occur if the MSN/LSB messages change assynchronously.. and at 100Hz, this can be heard!

I still think that, for the price, this is probably an extremely good product - IF one doesnt expect too much from it..

For those interested, a PSoC Proximity kit can be bought from http://www.onfulfillment.com/cypressstore/Category.aspx?d=30&spd=&sid=205&pg=1 CY3235-ProxDet CapSense Proximity Detection Demonstration Kit .. but for $68 each (2 required to even start making a Theremin) buying the 2008 is probably the cheaper option!
Posted: 4/23/2008 2:15:18 AM
Alan_in_CA

From: Fresno, California USA

Joined: 3/26/2006

Thomas--
It looks to me like there is a rocker switch on the left for power, and two sliders, probably one for each antenna. Same as knobs.

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