Project files: Mono op-amp buffer/driver

What is it?
This is a board for a generic mono buffer/gain stage based on a single op-amp. Depending on the chosen op-amp, the board can be used as a preamp or headphone amp on its own or be combined with a suitable output stage for even more oomph. The board requires a dual, regulated DC power supply (for details on voltage/current ratings, refer to the spec sheet of your chosen op-amp).
This board has the same hole dimensions as the discrete Alpha20 buffer from AMB and while the connections are not 100% identically located, the boards should be interchangeable in most applications.

How big are the boards?
Boards measure 1.8×1.4″ (app. 46x36mm) which means they are just small enough to be made very cheaply by Itead or several other companies.

What is the status of the boards?
This board is in version 1.2. Version 1.1 added an LED to indicate power (on the positive rail only though). Version 1.2 incorporates minor changes to the silkscreen and a change of signal spacing from 6 to 8mil. Both versions 1.0 and 1.1 have been prototyped and seem to work fine.

Does it use any special/expensive/hard-to-find parts?
No, not really. You can use a really expensive op-amp such as the AD797 or the OPA627 if you want though 🙂

Anything else I need to know?

  • The output socket has two GND terminals because the board was originally intended to work with ICEpower ASP-series amp modules. These have differential inputs, so when connected to an SE buffer the In- terminal needs to be grounded.
  • The bandwidth limiting cap (C3) is intended to be mounted inside the socket for the op-amp. If you are not using a socket, you can mount it on the back of the board. The footprint is for a 2.5mm leaded type but a 0805 SMD cap should fit between the holes as well without issues.
  • Note that the spacing around certain parts (mainly R4 and R6) is quite tight, so be careful when populating and soldering the boards.

Download design files here

Related information:
Note: Always read the “intro post” for additional important information about my designs.



One Response to Project files: Mono op-amp buffer/driver

  1. Pingback: One amp to rule them all? | theslowdiyer

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