Tube VCA ttt
TUBE VCA / DISTORTION / WAVESHAPER / TIMBRAL GATE / etc. for Eurorack - true syle! No wiring! Other formats and 15V - possible!
This design is inspired by Ken Stone's Tube VCA and based on 60s-70s soviet tube 1Ж24Б. (I've contacted with Ken and got his blessing. Hi specified to write 'inspired by' since it's modified unofficial release. Thanks Ken for help and sharing!)
Power consumption: V+ 12mA, V- 25mA.
PCB - 2mm thickness, gold platted, black mask. $25
Two panels - 10HP front & back. Anodized alu, black print. $25
Tube 1Ж24Б. $5 (I don't sell tubes without boards)
SMD parts + soldering. $10 (Who order SMD soldering please note if 15V version in payment comments, I make 12V by default)
Shipping per set: $5 - only board, $8 - board+panels.
TOTAL for complete set with shipping: $73
Assembled module $260 + $10 shipping.
Thread at MuffWiggler forum http://www.muffwiggler.com/forum/viewtopic.php?t=66598
Demo from ddoyen@Muff :
A kick drum through the L-1 Tube VCA. From "clean" to nasty. from DarkSideoftheTune :
The design is adapted for Eurorack format but 15V is possible with changing of resistor value. Boards have mounting holes for M3 screws, footprints of potentiometers, switches and power connector are compatible with MTA100 headers. Jacks can be wired with shielded or other wires. So 5U-ers are welcome.
PCB from both sides:
PCB with soldered SMD parts:
MOUSER SHOPPING CART. MERCHANDISE TOTAL: $30.29 (USD)
Parts not included in Mouser shopping carts:
Where to buy?
I included into Mouser shopping cart 8 Kobiconn jacks. But they need to solder a leg for ground connection.
This is build of roglok@Muff. Nice example how to use a board in other formats. 5-pin MTA-100 header can be used as power socket too.
Rod radio tubes, where the control electron flow is not using grids, blocks the electron flow, as in conventional tubes, and rods using electrostatic lenses that change the intensity and focus the electron beam - this is a brilliant Soviet development.
They were developed in the USSR by V. N. Avdeev (1915-1972) in 1950 and meant the most significant change in design classic from the invention of electronic amplifying triodes in 1907.
They were created for battery powered military and space equipment. The mass distribution obtained in the early 60s. They have great reliability, shock and vibration, stability parameters, durability, comparable to the transistor, and the "lamp" radiation resistance makes them ideal amplifying device to operate in conditions of radiation and cosmic rays.
Very similar tube 1П24Б was on a radio transmitter on the first soviet sputnik in 1957. These tubes were into a radios on other manned and unmanned space vehicles, including the Vostok.
As far as is known they were never used in Domestic Radio, but in Military and Aerospace including "man pack" radio sets. Production is believed to have ended as late as 1991 with one estimate of 200 Million made.
All soviet army radios used these tubes too.
Assembling is pretty easy. Everyone can do it in a couple of hours.
Solder through-hole parts from low to high. First 10R resistors and diodes.
Then IC sockets.
Then caps, power socket and trimpots. From low to high.
A 'pillow' for tube. I made of foam from IC's packaging.
Isolate tubes legs with shrink tube. Blow hot air.
Install tube. Dot on tube => 1 pad on PCB.
Now clean bottom side. Look how clean it is obtained.
3. Mounting hardware.
Erthenvar jacks are too high in comparison to Kobicon. Cut these legs with pliers. We need to achieve 10mm between board and panel.
Kobiconn jacks need ground leg soldering. I use cutted resistor legs.
These spikes on pots need to be cuted.
Now insert all hardware but don't solder.
I use thin washers with Kobiconn jacks to achieve 10mm.
Now place a panel. Don't overtighten a nuts, just by hand.
Check everything is exactly precise.
Now solder. Be accurate, hard to clean now if to make dirty.
Now tight a nuts, not strong just a bit. Pots have a washers, so screwdriver doesn't scratch a panel.
Switches and jacks haven't washers, so some protection is needed, I use insulating tape.
Ready. Very nice and precise.
Now device is ready for backpanel mounting and power-up.
The device is ready!
1. Zero CV level.
Feed some signal into IN1. 1 kHz sine vawe from an oscillator will be fine. Set IN1 knob to max, set GAIN knob to 0.
Adjust 100K_CV trimpot on a board to hear nothing at out.
2. Distortion amount (trimpots on frontpanel).
Trim them on ear as you prefer.
(c) 2012 L-1 Synhesizer. E-mail: firstname.lastname@example.org