Project
Projecttitel: MOTM 830 Mixer
STATUS finished
Startdate: 25.11.2013
Duedate: 15.12.2013
Manufacture link: http://www.synthtech.com/motm830.html
further links:http://www.dragonflyalley.com/constructionMOTM830.htm
About the module ( copy from synthtech)
The MOTM-830 is a dual mode (audio and/or control voltage) mixer. Using a clever switching scheme, the mixer can configure itself into either 6:1 or dual 3:1 mixers. The mixer is "split" when a patchcord is inserted into the OUT 2 jack.
The MOTM-830 is unique in the modular world: it is optimized for both audio signal quality and DC stability. Other mixers are generic, TL072-type mixers which are OK for audio but suffer from input offset voltage drift over temperature. The MOTM-830 uses special circuitry to provide superior audio specs (less than 0.005% THD, greater than 90dB SNR) while having superior DC specs (less than 1uV/C drift). Other features include:
- Shielded cables on ALL signals
- DC Bias generator: module can act as DC source!
- Mixer #1 (IN1 - 3) uses linear pots, while Mixer #2 (IN4 - 6) uses audio taper pots
- All pots are sealed, conductive plastic for long life and low noise
Easy to build, the MOTM-830 is a valuable addition to your MOTM system.
Userguide - Buildingguide
Modifications
http://www.tellun.com/motm/mods/motm830/motm830.html
Increase Gain
Changed some resistors to get unity gain from any input to any output.
- Changed R8 and R17 from 44.2K to 100K (1%).
- Changed R18 from 100K to 49.9K (1%).
Gallery |
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BOM:
RARE Parts:
the Op285 was ordered from littlediode
pots from bridechamber and mouser
PCB, Panel, Bracket, pots from Bridechamber
| Capacitors | ||||||||||
| Radial Electrolytic - tol:+/- 20% | ||||||||||
| 10μF,50V (this has poles) | 2 | Mouser | Xicon | 140-XRL50V10-RC | 1 | 1 | $0,06 | 2 | $0,12 | |
| Axial Ceramic Caps | ||||||||||
| .000022uF (= .022nF = 22pF) | 1 | Mouser | Xicon | 147-75-220-RC | 1 | 1 | $0,27 | 1 | $0,27 | |
| .1uF (= 100nF = 100,000pF) | 7 | Mouser | Xicon | 147-72-104-RC | 1 | 1 | $0,16 | 7 | $1,12 | |
| Caps Subtotal | $1,51 | |||||||||
| Project Subtotal | $1,51 | |||||||||
| Resistors - 1/4 W - 5% (unless resistors are specified as otherwise, assume they're 5% - Paul lists them as 5% - extra clear!) note: there is a price breakpoint on the 5% Rs that makes it super-cheap to buy 10 of them. I always do and put the extras away for when we need them. | ||||||||||
| 1K ohm (2K2) | 2 | Mouser | Xicon | 291-1K-RC | 1 | 1 | $0,10 | 1 | $0,10 | |
| 10 K ohm | 3 | Mouser | Xicon | 291-10K-RC | 1 | 1 | $0,10 | 4 | $0,40 | |
| 44.2 K ohm (44K2) 1% | 2 | Mouser | Xicon | 271-44.2K-RC | 1 | 1 | $0,13 | 1 | $0,13 | |
| 49.9 K ohm (49K9) 1% | 2 | Mouser | Xicon | 271-49.9K-RC | 1 | 1 | $0,13 | 1 | $0,13 | |
| 51K ohm | 1 | Mouser | Xicon | 291-51K-RC | 1 | 1 | $0,10 | 1 | $0,10 | |
| 100 K ohm 1% | 13 | Mouser | Xicon | 271-100K-RC | 1 | 1 | $0,13 | 3 | $0,39 | |
| 150 K ohm 1% | 1 | Mouser | Xicon | 271-150K-RC | 1 | 1 | $0,13 | 3 | $0,39 | |
| Resistor Subtotal | $1,64 | |||||||||
| Project Subtotal | $3,15 | |||||||||
| Semiconductors | ||||||||||
| TL072 dual op amp | 1 | Mouser | STMicroelectronics | 595-TL072ACN | 1 | 1 | $0,95 | 1 | $0,95 | |
| OP285GP | 2 | Synth Tech | these are very hard to find | 1 | 1 | $8,00 | 1 | $8,00 | ||
| you may have to sustitute a OP275 | ||||||||||
| IC Subtotal | $8,95 | |||||||||
| Project Subtotal | $12,10 | |||||||||
| Misc | ||||||||||
| Axial Ferrite Beads | 2 | Mouser | Fair-Rite | 623-2743002112 | 1 | 1 | $0,12 | 3 | $0,36 | |
| MTA .156" Connectors FRCTN LK HDR STR 4P Square post, tin | 1 | Mouser | Tyco | 571-6404454 | 1 | 1 | $0,30 | 1 | $0,30 | |
| Toggle Switches SPDT on-none-on | 1 | Mouser | NKK | 633-M201202-RO | 1 | 1 | $4,50 | 1 | $4,50 | |
| Misc Subtotal | $0,66 | |||||||||
| Project Subtotal | $12,76 | |||||||||
| Pots / Trimmers | ||||||||||
| Set of 100K log taper Spectrol 148 pot - this has 4 pots - these pots are very diffcult to find | 1 | Synth Tech | 1 | 1 | $30,00 | 1 | $30,00 | |||
| 100K conductive plastic Spectrol 148 log pot | 3 | Mouser | Vishay/Spectrol | very very hard to find | 1 | 1 | ||||
| Set of 100K cermet Spectrol 149 pot - this has 2 pots and ends up being much less expensive than getting them from Mouser | 1 | Synth Tech | 1 | 1 | $15,00 | 1 | $15,00 | |||
| 100K cermet Spectrol 149 pot | 1 | Mouser | Vishay/Spectrol | 594-149-7104 | 1 | 1 | $12,97 | do the math! If you're doing another module, it pays to buy the set from Paul | ||
| Bourns 100K panel mount | 3 | Mouser | Bourns | 652-95A1A-B28-A20 use: 91A1A-B28-A20L | 1 | 1 | $8,08 | 3 | $24,24 | |
| Pots Subtotal | $69,24 | |||||||||
| Project Subtotal | $82,00 | |||||||||
| Jacks | ||||||||||
| 2 Conductor Closed Tip 1/4" jack (112A type) | 7 | Mouser | Switchcraft |
| 1 | 1 | $1,89 | 7 | $13,23 | |
| Closed tip Closed ring jack (114B type) | 1 | Mouser | Switchcraft |
| 1 | 1 | $3,35 | 1 | $3,35 | |
| lock washer | 8 | Mouser | Vishay/Spectrol | 594-512-0008 | 1 | 1 | $0,13 | 8 | $1,00 | |
| Jacks Subtotal | $17,58 | |||||||||
| Project Subtotal | $99,58 | |||||||||
| Wire | ||||||||||
| Power Cable - 20" | 1 | Synth Tech | 1 | 1 | $7,00 | 1 | $7,00 | |||
| Wire Assortment | 1 | Synth Tech | 1 | 1 | $8,00 | 1 | $8,00 | |||
| Coax assortment | 1 | Synth Tech | 1 | 1 | $9,00 | 1 | $9,00 | |||
| OR you could buy a bunch of wire and do it yourself. | ||||||||||
| Belden Hook-Up Wire - 22AWG, box of five 100foot spools, different colors | Mouser | Belden CDT | 566-9531 | 1 | 1 | $134,68 | ||||
| Belden Co-Axial Cable 100 foot spool - RG174/U 26AWG BLACK | Mouser | Belden CDT | 566-8216-100 | 1 | 1 | $51,70 | ||||
| Wire Subtotal | $24,00 | |||||||||
| Project Subtotal | $123,58 | |||||||||
| Hardware | ||||||||||
| Large BR-1 mounting bracket | 1 | Synth Tech | 1 | 1 | $8,00 | 1 | $8,00 | |||
| #6-32 x 1/2 screws | 4 | Mouser | Keystone | 534-9409 | 1 | 1 | $0,08 | 4 | $0,32 | |
| 1/4" al spacers | 4 | Mouser | Keystone | 534-398 | 1 | 1 | $0,14 | 4 | $0,56 | |
| #6 KEPS nuts - these come in a bag of 100 | 6 | Pointe-Products.com | 10607-P | 1 | 100 | $6,70 | ||||
| count them individaully - here' how they add up: | $0,07 | 6 | $0,40 | |||||||
| Tie Wraps | 9 | Mouser | 3M Electronic Specialty | 517-41932 | 1 | 1 | $0,04 | 4 | $0,16 | |
| 8 ALCO knobs - so look, if you'r only building this module, you can buy these guys at Mouser… but otherwise think about buying them from Paul - much less expensive | 1 | Synth Tech | 1 | 1 | $16,00 | 1 | $16,00 | |||
| knob - Alcoswitch | 7 | Mouser | Tyco Electronics / Alcoswitch | 506-PKES90B1/4 | 1 | 1 | $3,33 | |||
| Hardware Subtotal | $25,44 | |||||||||
| Project Subtotal | $123,58 | |||||||||
| PCB / Panel | ||||||||||
| MOTM-830 Mixer pc board | 1 | Synth Tech | 1 | 1 | $39,00 | 1 | $39,00 | |||
| MOTM-830 front panel | 1 | Synth Tech | 1 | 1 | $39,00 | 1 | $39,00 | |||
| PCB/Panel Subtotal | $78,00 | |||||||||
| Project Subtotal | $201,58 | |||||||||
| Solder | ||||||||||
| heat-shrink 1/8" - four foot length - you need this | 602-221018-4BK | 1 | 1 | $1,50 | ||||||