U47 microphone build

The COVID pandemic has changed so much for so many lives, mine included. Deciding to use the gift of discretionary time to full advantage I set out to do something I’ve always wanted to do – experiment with building tube microphones! (Let me be clear that I am hardly an expert on tube circuit design so please be gentle if there are any inaccuracies below.)

For a number of reasons, and fueled by our success in building four extremely musical and often used Neumann U87 clones in 2015 (read that article here), I chose this time to build a pair of U47 type mics. I am fortunate enough to own many great microphones, including 2 Telefunken U47’s (more on those in a minute) but was lacking a set of mics with what I fondly think of as “47-ness,” the warmth, open bottom end; silky smooth extended highs, and a notable proximity effect boosting lows without an inherent compression signature. (more…)

The Big U-87 Mic build post

A few months back, we built four U-87 clone microphones here at the studio. They’ve since been in regular use in many of the roles an 87 might play in a busy studio; string section, saxes and other winds, lead and group vocals, guitars and amps, and they are fantastic. They have all the depth, tone, accuracy (and inaccuracy) and proximity effect signature of microphones that cost at least 6 times as much.

Since so many people have been asking for details on the build, my friend and colleague Daniel Noga, who headed the whole mic build project, did this great write up on the entire process from ordering parts to listening to the final build. (more…)

Ampex 351 preamps

Ampex 351 preamps
Ampex 351 preamps

Well, it took a while, but I finally have most of my 6 Ampex 351 pre-amps built. They sound great, I’m really pleased. Following the mods and circuit edits developed by Electrical Audio, we made new circuit boards (thanks to Ian Anderson for his PCB help) and, having gutted the old units of all but the transformers and BIG meters, created our own version of this classic tube pre.

Using real high end components from manufacturers like Mojotone, Vishay and Hairball Audio, the result is a classic sound with low noise floor and a wide range of tone from clean to “OH MY GOD”. I’ve used the prototype with ribbons and condensers (we added an onboard soft start phantom supply) and just love it.

All the documentation from Electric is available in the Schematic Vault http://dev.danrudin.com/Schematic_vault/index.php?dir=Ampex/ and I’ll try to post my own mods and tweaks when I have a minute.