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Kulu, your Altura MkII is repaired and headed home! This turned out to be a QC issue with installation of the far left, Data Far knob, which frankly got worse when you tried to replace the knob yourself. 😉 We have installed a new knob yet again, and we had to jump a couple of connections where the PCB pads were damaged beyond use. So sorry for the delay. Your Altura Theremin is ready to wave!
Is the LFO light blinging 2-4-2 … 2-4-2 .. ? This is a service easter egg: when you power up with the bypass switch depressed, the pedal starts in a calibration mode, and the LFO light flashes out the software version; in this case, v2.4.2.
This suggests that your footswitch may be shorted to ground, that is, the pedal thinks it is depresses (closed) all the time. Double check the wiring of that switch, or even disconnect it for a moment to test.
Beyond that, I must defer to Brach, the technical guru, who is out at the moment on maternity leave. I will ask him to check in with this thread when available.Glen
Mac, you are on the trail! First let me mention that it was an oversight that we failed to post a response to this thread: we talk with Ian a lot, mostly off line, and I overlooked this post. Mac, each key has a different capacitance influenced by its size, shape, and position on the PCB. The resistors were selected after some theoretical analysis and LOTS of empirical trial-and-error. Plus the whole system is influenced by its environment: temperature, humidity, and how dry your skin is! So we have found the following tend to stabilize the keyboard:
- Touch one finger not to a resistor or the battery, but ANYWHERE on the PCB outside the 13 keys.
Experiment with a wall-wart power supply instead of battery, and earbuds or other external speakers instead of the (sketchy) on board speaker.
Lick your fingers before playing!
Adjust that E resistor down to a lower value.
Playing with the MIDI IN jack, controlling the Macchiato with an external control keyboard or sequencer, bypasses the capacitive touch keyboard all together and performs with no instability.Regarding a metal case: Not such a good idea. The metal itself, if it contacts the PCB at any point, will affect the capacitance of the whole system. However, one user had great success adding an additional ground plane to the bottom-inside of the cabinet. I think he used a piece of heavy aluminum foil (copper would be MUCH better) and a little wire that he connected to ground at the center of the board, possibly using the center standoff screw. This gave him good stable performance. He found he had to isolate the foil from the five screws in the cabinet bottom; otherwise, when he held the synth in his hand, touching any screw would throw it off again!!
Glen
Kulu, so sorry we did not respond sooner. Holidays, you know. Yes of course, we will keep an eye out for your shipment and we will take care of you.
Innes, you are my new favorite customer of the week. I shipped your new kit this morning. Merry Christmas, Happy New Year, and to all a good night.
You are doing great work! Your analysis suggests that the Altura might be working just fine, except for the display! Go ahead and plug a MIDI cable into the device and connect it directly to the MIDI IN of a synth. (Do not try connecting to a computer synth for a first test.) Make sure you plug the sensor cables in correctly, not backwards. You had it correct initially. Point the sensors up toward the ceiling, not down to the table. Set the knobs as described in the Quick Start guide: left, right, 9 o’clock, left, left, noon, noon. This should give you one octave of C Major on the right sensor, and control over modulation or note velocity on the left sensor. The unit will default to transmit on Channel 1 on power up. Go ahead and see if you can control your synth. Do you see any activity on the MIDI light on the slave synth?
When he is able, Altura designer Brach will comment on possible faults in the circuit that could account for the display’s power issue.
Good work! Hey, this is part of the fun!Innes, thanks for the video; it is invaluable! Sorry you’re having a little trouble getting your altura fired up, but congratulations on giving it a shot! It is a moderately ambitious project for a first-soldering experience. You seem to have been thorough in your troubleshooting. We are going to look at two things:
1) Are you getting 5V DC distributed around the board? Check the DC voltage to ground at a few places around the board, with the battery in and the power on. Consult the circuit diagram to spot the power pins on the MCU (marked VCC). Also the sensors are easy to measure. Unplug them from the board. One of the end pins should show 5V DC. What do you find?
2) there are three 14-pin ICs that look pretty similar: the multiplexer, shift register and hex buffer, located at U2, U3 and U4 respectively. Examine the nearly-invisible markings on these three components. Are they in fact three different components, with no duplicates? (It happened once.) Are they each in the correct location, in the correct orientation? Any error would account for the observed behavior.
Let us know what you discover.That sounds like a defective pot. We see them about once in every 1200-1500 pots. Our QC process should have caught that, but sometimes the bad behavior is erratic and the unit works fine during testing. If you are willing, I will send you a couple of pots and you can replace the naughty one. Consult the kit assembly instructions to see how we assemble the unit into the cabinet, and follow it in reverse to take it apart. I will need your serial number (on the PCB, starts with ZD) to look up your order.
I’m very sorry for the trouble, but very glad you like/appreciate the design. That makes it all worth coming in to the Lab each morning!Glen
Don’t turn it on! It sounds like a ground fault. Look for put pins shorted to each other or to ground.
Plasti dip on the outside is strictly optional. It looks neater, and helps hold the copper tape together longer, but is otherwise non essential. Our tests show no measurable difference in sensitivity, but theoretically it costs you something. Inside the mic, between the piezo and the copper tape, it is essential to insulate the disc from the tape. Plasti dip has proven very unreliable for this purpose, so we only recommend a layer of electrical tape.
As for the tin can mic question: Please look at our silly videos promoting the Hula Mic gimmick. This project involved clamping or sticking a complete, shielded mic to all sorts of trash. It is still quite sensitive. The object itself is a much bigger factor in how the mic sounds than the layer of tape on the mic.
In all cases, the sound is heavily influenced by how well the mic is coupled to the vibrating object. Whenever possible, use a little spring clamp and a pad to hold the mic down firmly to the edge of your object. When that’s not possible, we like to use a very small bit of poster tack, mushed up warm and soft, squeezed into a thin sheet, to stick the sensor to the middle of the vibrating object.
I hope this helps?
Oh yes, it is certainly still happening. We are holding details close to the chest as we continue with our R&D. No release date yet. Sign up for our newsletter to stay abreast of developments…
Yep, that’s an upside down transformer for sure. These are custom made for us, and apparently one small batch was made with the outer sheet metal enclosure installed the wrong way. You can fix this yourself by bending out the little retainer tabs on the bottom of the transformer, peeling off the sheet metal shell, and flipping it around, installing it again the correct way. If you would rather not deal with this, contact us about an exchange.
Besides those two videos, there is a detailed assembly manual available for download from the combo page at https://www.zeppelindesignlabs.com. Winging should not be necessary. But no, we did not shot a separate build video for the combo.
- Touch one finger not to a resistor or the battery, but ANYWHERE on the PCB outside the 13 keys.
