Three Great 500 Series-Compatible Microphone Preamplifiers (Part 3) - Classic API Heider FD312

In addition selling components to aid in the restoration, repair and modification of API consoles, Classic API (Audio Products of Illinois) has several 500 Series kits, the majority in the $175-275 price range, allowing DIYers to build high-quality mic preamps at a fraction of the price of fully manufactured units. Last fall, Classic API released the Heider FD312, the only Classic API model not available in kit form, distributed exclusively by Nashville’s Rack-N-Roll Audio. The Heider FD312 was modeled after the preamps in the legendary Wally Heider Recording Studio 4 console that was custom built by Frank De Medio in the early ’70s. These pres were built around stock 312 cards that De Medio modified by replac-ing the stock input transformer with a cus-tom-wound Ed Reichenbach RE-0887 trans-former which he interfaced differently than the stock transformer; this resulted in a smoother, more musical midrange. Utilizing Ed Reichenbach’s original notes and specs, Cinemag builds the RE-0887 input trans-formers utilized in the Heider FD312.Unfortunately, there is no instrument input on the Heider FD312, though it includes both Mic and Line inputs. In Mic mode, the gain ranges from +22 dB to +57 dB with an input impedance of 167 ohms; in Line mode, the gain ranges from -14 dB to +21 dB with an input impedance of 9 kΩ.. While I’ve never found myself looking for a line input on a solid-state pre, I’ve fallen in love with the character of the FD312 when operating in Line mode. I’ve been running my ITB mixes through two channels in Line mode set to unity, and I’ve found that the pre adds loads of character to my mix with a smoother top end and improved definition.

Classic Audio Products of Illinois Heider FD312WHR4

In addition to the preamp circuit, the module employs an active booster stage, providing up to 12 dB of gain - identical to the boost circuit utilized in early- to mid-’70s API desks. As with other two stage mic preamps, you can attain more color and harmonic content by increasing the preamp gain and pulling back the Channel Fader, or a more pure tone by setting the Channel Fader to unity or slightly higher and pulling the preamp gain back.

Classic API Heider FD312 inside

Activating the Hi-Z function (nearly always my sonic preference) increases the input impedance to 300 ohms and raises the gain by 3 dB. Activating the pad inserts a 16 dB pad and increases the input impedance to 765 ohms. All of these different impedance changes are wonderful as they provide tons of creative options while dialing in a sound. The stepped channel fader provides a final -16 dB to +12 dB gain stage, making the preamp’s maximum gain 72 dB in Mic mode with the Hi-Z engaged, and 69 dB with the Hi-Z not engaged. The FD312’s maximum output level is +29 dBu and it includes a beautiful 12 segment, -22 to +16 VU meter that ranges from green (-22 to 0) to yellow (+3 to +12) to red (+14 to +16) where 0 VU = +4 dBu.

I first used the Heider FD312 to record kick and snare on a tracking session. The pre sounded fantastic; I found myself using substantially less-than-typical EQ. On another tracking session, I used the pre on toms and was blown away again. When it comes to recording drums, the Heider FD312 is super. It’s punchy as hell, with tons of character, leaving nothing to be desired. The pre also excels with acoustic instruments and vocals.

The best way I’ve found to describe the Heider FD312 is like a classic API mic pre but better. It has all of the rich punch and clarity of an API with a milky-smooth midrange that sounds as musical as any pre I’ve ever encountered. The Heider excels on drums and electric guitars, but is equally fit for recording vocals and acoustic instruments.

Summary

The Sonic Farm Silkworm, Electrodyne 501 and Heider FD312 are all three wonderful mic preamps. If this was a shoot-out, I’d have to call it a three-way draw because they are all winners. All are packed full of character, reasonably priced and fantastic performers. If you can afford it, I’d recommend getting a pair of each. And, on the microphone front, MXL continues to impress with its high-quality mics that are surprisingly affordable.

Next PAR, I’ll delve into Moog’s 500 Series Ladder Filter and Analog Delay as well as some other surprises.

Heider FD312 Mic / Line Preamp