Sunday, 17 February 2013

AMZ Super Buffer

Request.

There are situations in which very long cable runs are necessary from the pedalboard to the amplifier, or a more powerful driving circuit is needed to the heavy load presented by devices in parallel. A good buffer box is the solution.
The best buffer board will present a high impedance to the input while having a low impedance output. This insures that the maximum clear signal will pass through unchanged to the output, and a low impedance drive can send the signal through long cables without losing much strength or response.
There are numerous special purpose chips that are designed as buffers for driving very long lines and/or capacitance loads. These ICs can be difficult to find and expensive. A simple solution for stompbox purposes is to parallel opamps and thereby boost the output drive. With attention to a few details, this is a simple project to build.


8 comments:

  1. Build it and works like a charm! Just what I needed. Thanks for this!

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    1. Excellent, thanks for verifying Tim

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  2. I've tried with 18v at the end of the chain. Adds some clarity and a little bit of compression. Is a subtle effect.

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  3. Will this fit in a 1590a enclosure? I'm having a difficult time googling what size vero will fit in specific enclosures (e.g. 23 rows is the maximum for a 1590b, 15 rows is the max for 1590a, etc.)

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    1. I think it may if you turn it sideways. Even if you have to sand the sides a bit...
      the max I can fit in a 1590B is 22 holes wide, and that by sanding the sides of the vero.

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  4. I've made a few buffers to put in my a/b box that I use as a guitar switcher. They add a bit of noise. Is there a specific way to ground it? I place it on the single output side. The a/b box has two LEDs for channel selection. Any drawings would be good.

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    1. If you have a noisy signal then a buffer tends to make the noise a bit more apparent. Moving them to their own enclosures would be really helpful but otherwise I'd suggest shielding them with a heavy piece of metal to protect them from any stray noise sources. Any time you combine circuits in one enclosure you introduce more noise. Ultimately/ideally you want a faraday cage completely enclosing each circuit. The other culprit is your cable-run from your guitar up to your buffer. Make sure you're using a good quality cable with no knicks or cuts in it. Planet Waves makes cheap cables that are slightly better than most budget cables and they come with a lifetime warranty. Mogami is great if you got the extra cash.

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    2. Alternatively you could lift the ground on one of the inputs to see if that helps because it seems like you could have a potential ground loop

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