A Discrete BUF634

There happens to be an electrical integrated circuit (IC) called the BUF634, which is used as an output buffer in a lot of DIY audio circuits. In the past, this hasn’t really been a problem, but for the last year or two it’s been a consistent headache, as availability of the BUF634 has been unbelievably erratic. It’s not uncommon for the chip to be out-of-stock everywhere for six months or more at a time, which is extremely inconvenient, to say the least.

There are parts from other manufacturers which are a direct, drop-in replacement, and which in many cases not only perform better but are cheaper, to boot. The catch is, replacements are really only available for the surface-mount version, leaving designs based around the through-hole, BUF634P version stranded.

Now, you can adapt surface-mount chips to fit the DIP8 socket, but it’s annoying, not to mention off-putting to those (unreasonably) scared of soldering surface-mount components.

Well, there’s a solution…

Some clever audio enthusiasts came up with a drop-in replacement for the through-hole BUF634P which uses entirely through-hole discrete components – a couple of transistors, a few resistors, and a capacitor. The resulting design is known as the “Monofied Sijosae Discrete BUF634”, and is generally agreed to offer audio performance superior to the original. Last year, a fellow on Head-Fi created a fairly simple double-sided PCB design for the buffer. You can etch ’em yourself, but drilling all the holes is a fiddly task, and not everyone is willing to make their own PCBs, so plans were made to have boards produced commercially for those interested.

Due to a variety of issues, the group-buy of the boards fell through after some months, leaving the audio community – and anyone else needing a drop-in BUF634P replacement – out of luck. The creator of the PCB made the design open source, and released his gerber production files to the public, so that those who wanted to could have their own made, one way or another.

Keep in mind, we’re talking about a board that measures 13×15 millimeters; if you wanted three of ’em, you’d wind up paying about $20 at BatchPCB, and have to wait three to five weeks.

That seemed kind of silly to me, so I contacted Seeed Studios, who make the Seeeduino microcontroller board, among other things, and they agreed to produce the BUF634P boards as part of their “Open-Source Hardware” project. It’s probably not quite what they had in mind when they started the program, but it seems to be a win-win situation for everyone.

Anyway, if you happen to need or want a high-current buffer replacement for the BUF634, you should check out the PCBs here. Shipping is ridiculously cheap, and takes about two weeks from China. I’ve got mine; get yours while you can. 🙂

Published in: Geekiness | on January 26th, 2009| 1 Comment »

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One Comment

  1. On 3/4/2017 at 7:39 pm mono Said:

    Thanks for the feedback. I am the creator yet sijosae did more of the work.

    FYI what drilling it yourself did was allow choosing a larger hole size so you could pull the pins out of a DIP8 socket and solder them into the PCB so it was truly a more durable drop in replacement for the BUF634.

    These PCBs don’t allow that. For what it is worth, I didn’t do this double sided nor use gerber files. It was all done by hand with old school Paint Shop Pro 7 from many years ago, because sometimes an old simple program is better at productivity.

    The irony is that I etched dozens of these PCBs from a single virgin copper clad board and still haven’t used up the remainder of so many I made. There was no need to.

    Thanks for keeping the DIY spirit alive.

    Mono