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$4,868 pledged of $10,000 goal
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All or nothing. This project will only be funded if it reaches its goal by .

By Abstrakt Instruments
$4,868 pledged of $10,000 goal
backers

All or nothing. This project will only be funded if it reaches its goal by .

About

This is your chance to help fund and procure parts for the iconic Oberheim OB-X synthesizer. This is a passion project which came about through product development & engineering. We have built and tested numerous assemblies from our favorite vintage synths for the purpose of studying the intricacies of each design. After testing, these parts are generally used in our in-house machines or neatly stored away. In the case of the OB-X, employees & visitors alike were asking to remake these parts. Since we are not in the primary business of selling parts or kits it took some convincing. These designs are completely finished. We've established a goal of $10k to make sure we have enough quantity to hit our pricing targets. If the goal is reached at the end of the funding period we will immediately send out for the parts to be made. We do not anticipate offering these parts for sale in the future. This project is more of a give-back to the vintage synth community as opposed to a practical money-making venture. 

Before getting into the details of the actual parts we'll clearly state what is being offered. We are offering various voice-related parts for the OB-X and synthesizer, including bare PCB's, fully assembled PCB's, and fully assembled kits.  

  • *OBX Voice Card PCB
  • *OBX Voice Card PCB Assembly
  • *OBX Motherboard PCB
  • *OBX Motherboard PCB Assembly
  • *OBX Motherboard Tray 
  • *OBX 4-Voice Expansion Kit
  • *OBX 8-Voice Kit
  • *OBX Filter Control Board Assembly  

Voice Card PCB

The *OBX Voice Card PCB is interchangeable with original parts. The layout is the same with the following improvements.

  • ENIG Gold surface finish.
  • Double-sided black soldermask.
  • Support for multi-mode filter. The 'Noise Half & Full' buttons can be used to select filter modes. This option requires our Motherboard PCB and Filter Control Board. No other modifications required.
  • Placements for 25-turn Bourns potentiometers for VCO adjustments
  • Placements for LM7815/7915 1.5A voltage regulators to upgrade the original 78L15/79L15 parts.
  • Placements for Panasonic FC radial capacitors to upgrade the original axial components.

BOM and Schematics available for parts procurement, costing, & assembly.

Voice Card PCB Assembly
 

The *OBX Voice Card PCB Assembly is fully populated, calibrated, and ready for use. Parts selection and substitutions versus the original parts are detailed below:

  • All IC placements include machined IC sockets. 
  • New old stock CA3086.  KRL tempco's are thermally bonded to the transistor array as on the original parts.
  • New old stock CA3080E.
  • New old stock Panasonic 'tropical fish' capacitors in the audio path.
  • CEM3310's are replaced with the AS3310. We have a relationship with Alfa Rpar and have been testing and spec'ing several of their new parts in our products currently in development.  The AS3310 performs the same as the original parts.
  • Bourns 25-turn trimmers are used for VCO-related calibrations.
  • ST LM9815CV & LM7915CV 1.5A voltage regulators replace the original 100mA parts.
  • Panasonic FC capacitors replace the original axial local power supply capacitors.
  • Polyester Film Capacitors are used for the envelope generator timing caps. They are the same tolerance and same characteristics as the original metallized polyester caps used.  

Motherboard PCB
 

The *OBX Motherboard PCB is interchangeable with original parts. Improvements include:

  • ENIG Gold surface finish. 
  • Double-sided black soldermask.
  • Support for multi-mode filter. 

BOM and Schematics available for parts procurement, costing, & assembly.

 Motherboard PCB Assembly  

The *OBX Motherboard PCB Assembly is fully populated and calibrated ready for use. Parts selection and substitutions versus the original parts are detailed below:

  • All IC placements include machined IC sockets.
  • Connectors are square tin-plated brass versus the original round tin-plated nickel pins. The female connector also has a higher tension constant than the original discontinued parts. These assemblies are more robust and should not become intermittent over the decades.
  • Additional connector installed to support multi-mode filter.

Please note there are two versions for the motherboard assembly. 

The *OBX Motherboard Assembly (Expansion) is to be used for voices 5-8 and not as the primary motherboard (voices 1-4). As on the original synth, only the parts that are required are installed. 

The *OBX Motherboard Assembly (Primary) is to be used for voices 1-4 as the primary motherboard (voices 1-4). As on the original synth, all parts are installed and the assembly is calibrated.

 Motherboard Tray   

This is the metal tray that is used for voices 5-8. It is powder-coated in black. This part is the same as the original part.

4-Voice Expansion Kit  

Fully assembled and calibrated 4-voice expansion. This includes four *OBX Voice Card Assemblies, one *OBX Motherboard Assembly (Expansion), one Motherboard Tray, and all connectors and hardware needed to upgrade a 4-voice OB-X to 8 voices. 

Please note: If multi-mode filter support is desired the Filter Control Board Assembly is also required.

8-Voice Kit 

Fully assembled and calibrated 8-voice retrofit. This includes eight *OBX Voice Card Assemblies, one *OBX Motherboard Assembly (Primary), one *OBX Motherboard Assembly (Expansion), one Motherboard Tray, one Filter Control Board Assembly, and all connectors and hardware needed to retrofit an OB-X with eight new voices with multi-mode filter support. 

Filter Control Board Assembly

This assembly is only needed if the multi-mode filter option is going to be used. This option requires our *OBX Voice Cards and *OBX Motherboard.  This board replaces component A31 on the OB-X Control Board. It contains two switches which determine the function of the Noise 'Half' & 'Full' buttons. The switches are readily accessible under the lid without having to move any parts. The switches allow for several modes:

  • Mode 1: Both noise half and full level are disabled. All filter mode selections are enabled, including low-pass, high-pass, and bandpass.
  • Mode 2: Noise full level is enabled and noise half level is disabled. High-pass filter mode is enabled, bandpass filter mode is disabled. This allows for both full level noise noise and high-pass filter to be used. 
  • Mode 3: Both noise half and full volume are enabled. Filter mode selections are disabled. This is the default standard OB-X mode.

 Please note: The majority of OB-X's have component A31 socketed. This makes installation easy. However, there are some OB-X's that do not have A31 socketed. In this case the original part will have to be removed first for the new filter mod control board can be installed.

Please note: This board can also be used as a convenient way to tap into the latches on A31 for custom mods and diy.

Schematic available for reference.

Disclaimer: We are offering these parts for the vintage Oberheim OB-X Synthesizer. The current status of the ownership of the original Oberheim name, logo, and the "OB-X" name are not known. Gibson, the most recent owner, is now in bankruptcy and is owned by a group of financial companies. We have specifically avoided using the original company name "Oberheim" and original model name "OB-X" in the naming of our parts. It may also be necessary to remove the brand and model name from the production PCB's. 

Risks and challenges

These parts have already completed design verification and are ready to be manufactured. However, the last step of documentation and delivery is not to be underestimated. The risk relates to delivery time. Delivery dates for some may shift depending on the number of parts that are ordered. Assemblies will be delivered in the order of pledge date. With the small number of OB-X's out there we don't expect delays to be significant.

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    *OBX Filter Control Board

    This assembly is required to enable the multi-mode filter option. This option requires our *OBX Voice Cards and *OBX Motherboard(s).

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    *OBX Voice Card PCB

    Bare PCB. Replacement voice card PCB for OBX.

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    *OBX Voice Card Tray

    Voice card tray only. Semi-gloss black powdercoat finish. This part can be used to replace an original part.

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    *OBX Motherboard PCB

    Bare PCB. Replacement voice motherboard for OBX.

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    *OBX Voice Card PCB (4-pack)

    Bare PCB. Replacement voice card PCB's for OBX.

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    *OBX Motherboard Assembly (Expansion)

    Assembled voice card motherboard for OBX voice expansion. This assembly includes all connectors and original pan pots.

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    *OBX Voice Card Assembly

    Complete with all parts installed. Pre-calibrated and ready for drop-in replacement.

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    *OBX Motherboard Assembly (Primary)

    Assembled motherboard for OBX voice cards. This assembly includes all parts.

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    *OBX Voice Card Assembly (4-pack)

    Complete with all parts installed. Pre-calibrated and ready for drop-in replacement. Four pieces.

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    *OBX 4-Voice Expansion

    Complete ready to use 4-Voice Expansion This kit includes everything needed for a drop-in 4 voice upgrade for a 4-voice OBX. This includes four voice card assemblies, voice motherboard assembly, motherboard tray, and all connectors and hardware needed to complete the expansion.

    This 4-voice assembly comes pre-built and calibrated, ready to plug in.

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    OBX 8-Voice Kit

    Complete 8-Voice Kit. This kit includes everything needed for a drop-in 8 voice upgrade for the OBX. This includes eight voice card assemblies, two voice motherboard assembly, one motherboard tray, and all connectors and hardware needed to complete the kit.

    This 8-voice assembly comes pre-built and calibrated, ready to plug in.

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