jdbakker
Well-known member
Hi all,
I am working on the design of a discrete microphone preamplifier which I am planning to release here (both as boards and self-etch). It occurred to me that, since all the world is going SMD, it would be interesting to have an easy My First SMDee project here in GroupDIY. Of course the plan would be to not make it too hard: have nice large pads, enough space between parts for (unexperienced) hand solderers and no parts smaller than necessary for best performance. However, before I start laying out a board I'd like to gauge interest as there's little point in setting up a group project if nobody feels comfortable building it. Of course, either in SMD or thru-hole all parts will be easily available from The Usual Suspects, and I expect build complexity to be similar to the Green or the SSL9k, so no crazy dense layout as on some of the DOA designs floating around here.
Thoughts?
JDB
[a bit of context: originally I didn't set out to design Yet Another Mic Pre. I was looking to build a line-in stage with good CMR and enough S/N to be below the noise floor of of modern ADCs. When you start doing the math, it turns out that the design goals are very similar to a wide dynamic range mic pre (<-120dBU noise floor, medium input Z). The design as it stands looks somewhat similar to the SSL9k, only with three fixed gain stages with a pair of ganged attenuators between them. And BTW, no matter whether the end result is SMD or thru-hole, the input transistors will have footprints for low-noise TO-92 transistors like the 2SB737, the MAT-03 and maybe even 2SJ74 P-JFETs. Or you can plonk in a pair of 2N4403s if cost is more important than that last dB of noise performance]
I am working on the design of a discrete microphone preamplifier which I am planning to release here (both as boards and self-etch). It occurred to me that, since all the world is going SMD, it would be interesting to have an easy My First SMDee project here in GroupDIY. Of course the plan would be to not make it too hard: have nice large pads, enough space between parts for (unexperienced) hand solderers and no parts smaller than necessary for best performance. However, before I start laying out a board I'd like to gauge interest as there's little point in setting up a group project if nobody feels comfortable building it. Of course, either in SMD or thru-hole all parts will be easily available from The Usual Suspects, and I expect build complexity to be similar to the Green or the SSL9k, so no crazy dense layout as on some of the DOA designs floating around here.
Thoughts?
JDB
[a bit of context: originally I didn't set out to design Yet Another Mic Pre. I was looking to build a line-in stage with good CMR and enough S/N to be below the noise floor of of modern ADCs. When you start doing the math, it turns out that the design goals are very similar to a wide dynamic range mic pre (<-120dBU noise floor, medium input Z). The design as it stands looks somewhat similar to the SSL9k, only with three fixed gain stages with a pair of ganged attenuators between them. And BTW, no matter whether the end result is SMD or thru-hole, the input transistors will have footprints for low-noise TO-92 transistors like the 2SB737, the MAT-03 and maybe even 2SJ74 P-JFETs. Or you can plonk in a pair of 2N4403s if cost is more important than that last dB of noise performance]