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Official Release: Heider FD312 Mic / Line Preamp from
Old 17th October 2013
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jsteiger's Avatar
Official Release: Heider FD312 Mic / Line Preamp from

Classic Audio Products of IL, Inc. and Rack-N-Roll Audio are very proud (and excited!) to announce the release of a new 500 series preamp! The Heider FD312. This is the very first fully preassembled preamp from my company. It has never been available as a kit and it never will be, only assembled. Rack-N-Roll Audio in Nashville will be the exclusive retailer of the Heider FD312 for an indefinite period of time. The preamps will be in stock and ready for immediate delivery as of November 1st, 2013. I will follow with some intimate details and try not to bore you ;-)

The Heider FD312 is a special and unique preamp module that stands out in today’s crowded 500 series market. The preamp stage has been carefully modeled after the preamps in the famous Wally Heider Recording Studio 4 console custom built by Frank DeMedio circa 1972. The original pre’s were stock 312 cards modified by DeMedio. Frank removed the (1:7) AP2622 input transformer and replaced it with a custom wound Ed Reichenbach (1:8) RE-0887. DeMedio removed the commonly used 1000pF decoupling capacitors found on the AP2622’s primaries. He also removed the Zobel network from the secondary. The RE-0887 design permitted the use of a single resistor on the secondary to reflect back to the primary an unusually low impedance without
high frequency ringing. All of this geek talk equals a very special tonal quality with some of the most buttery smooth mids you will ever encounter! CineMag owns Reichenbach Engineering and continues to manufacture all of the original designs to original specifications. CineMag has done a fantastic job with the current RE-0887’s, working straight off of Ed Reichenbach’s original notes and winding data from 1972. For those who don’t know, Ed Reichenbach’s son Tom went on to form CineMag in 1979 after working with his father for some 25 plus years. After Ed passed away, David Geren and Tom Reichenbach bought Reichenbach Engineering to continue the legacy. I am so very glad they kept all of the old notes!

To enhance this special preamp circuit even further, I chose to employ a stepped “fader” and active booster stage, very reminiscent to my popular 2-stage VP28 preamp. This is essentially the same booster circuit that was used in the early to mid ‘70’s vintage API consoles. In remaining true to the Heider circuit, all AC coupling capacitors have been removed from the audio path. I don’t think coupling caps are evil, they are just not needed in this particular circuit. This fader booster stage has 12dB of gain “in hand”, exactly like a real console. This allows for many different gain combinations. You can crank the fader and reduce the preamp gain or in contrast, attenuate the 2nd stage and crank the preamp gain for some sweet, additional harmonic content.

The original Heider/DeMedio preamp cards used stock AP2503 output transformers. With the desire to have something unique, I was luckily able to persuade David Geren, owner of CineMag, to think about the sonic characteristics of that transformer and create something different while retaining the sonic characteristics I was after. Out of his effort the CM-3301 was born.

In trying to be loyal to the console signal path, both gain stages have a CM-3301 output transformer. The first or preamp stage output transformer provides +6dB of gain, blocks DC from the stepped fader and imparts a little more character into the overall circuit, as compared to a “direct” output.

The operational amplifiers are the pure heart of any preamp like the Heider FD312. I naturally wanted to stay as close as possible to the discrete Studio Systems opamps from the early '70's. In a current commercially available product, Scott Liebers’ SL-2520 Red Dots were a no-brainer choice. As most of you already know, they perform and sound outstanding all while having a very long life expectancy due to their un-potted construction. Each Heider FD312 contains two of these glorious Red Dots.

In a goal to stay domestic, I would like to point out some interesting info. The Heider FD312 is assembled by a Chicago area electronics contract manufacturing house. Not the cheapest guys around but their work is outstanding. Each and every Heider FD312 is fully tested, calibrated, burned in and packaged by myself, at the Classic Audio Products laboratory. The following items used in the build are fully manufactured in the USA: All metalwork including zinc plating, anodizing and silkscreen printing, PCB’s, all transformers, opamps, aluminum control knobs, colored knob inserts and Grayhill switches. That basically leaves board level components as the only imported items.

Street Price: $750 available from Rack-N-Roll Audio, Nashville

Key Operating Features:

In MIC mode, the stepped PREAMP GAIN ranges from +22dB to +57dB, with an input impedance of 167 ohms.

In LINE mode (MIC pushbutton out or disengaged), the stepped PREAMP GAIN ranges from -14dB to +21dB, with an input impedance of 9K ohms.

Engaging the Hi Z pushbutton in MIC or LINE mode will increase the gain by 3dB. In MIC mode, the resulting input impedance will also be raised to 300 ohms. Since the upper ten PREAMP GAIN steps are also in 3dB increments, this allows for many creative tonal combinations.

The PAD pushbutton equates to 16dB of attenuation in either MIC or LINE mode. With the PAD pushbutton engaged while in MIC mode, the input impedance is 765 ohms.

The stepped CHANNEL FADER switch and 2nd stage booster amp provide a range of –16dB to +12dB in addition to the above-mentioned preamp gain ranges. This equates to a maximum gain of 69dB when in MIC mode and 72dB when in MIC mode with the Hi Z pushbutton engaged.

Accurate metering of the final output signal is achieved using LM339 quad comparators in a “console” style configuration.

Physically and electronically fully VPR compliant.


· MIC Preamp Gain Range: +22dB to +57dB (+3dB with Hi Z engaged)
· LINE Preamp Gain Range:-14dB to +21dB (+3dB with Hi Z engaged)
· 2nd Stage Booster Gain Range: -16dB to +12dB
· Pad Attenuation: -16dB
· MIC Mode Maximum Input Level: +6dBu, < 1% THD
· LINE Mode Maximum Input Level: +28dBu, < 1% THD
· MIC Input Impedance: 167 ohms, 300 ohms W/Hi Z engaged, 765 ohms W/PAD engaged
· LINE Input Impedance: 9K ohms
· Output Impedance: 70 ohms, transformer balanced
· Maximum Output Level: +29dBu, < 1% THD
· Frequency Response: +/- 0.25dB 20Hz to 20kHz
· Equivalent Input Noise: -115dBu unweighted (-93dBu actual metered noise)
· Distortion: Less than 0.03% @ +4dBu output
· Current Draw: Less than 101mA (under typical operating conditions)
· Meter Scale: -22 to +16 in 12 LED segments, 0VU = +4dBu

Thanks for reading! Cheers, Jeff

PS: Some male vox clips can be found here John Kennedy quick sangin' test

Some resonator guitar clips can be found here Randy Kohrs-Slack Key Studio Reso gtr clips
Old 17th October 2013
Lives for gear
analogtodd's Avatar

Nicely done Jeff, now yet 2 more boxes I need to buy from you!
Old 17th October 2013
Gear Maniac
cowrange's Avatar

Old 17th October 2013
Gear Maniac
mattallen's Avatar

I was able to use a pair of these for a week of tracking and overdubs a few months ago.
They were really enjoyable and fun to use as I'm mainly using the AMSNeve 88RS console preamps for everything.
The Heiders had a great firmness in the low end that I instantly loved. They have their own 70's signature as described, and I loved their "forward" sound compared to the 88RS.
Really well made piece of gear and you won't meet nicer guys than Jeff of CAPI and Rob from Rock N Roll.
Old 18th October 2013
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brianellefson's Avatar
Ugh. Just when I got up to speed with VP26's and VP28's ... now this.

I think I need two.
Old 18th October 2013
Gear Head
AdamNewman's Avatar

I'm starting a "My wife hates Jeff Steiger" support group if anyone is interested.
Old 18th October 2013
Gear Addict

167 ohms input impedance is so f$$$$$$$g sick! I would just love to hear sm57 on snare into that! I really enjoy shure dynamics being loaded down on drums!

That looks like a killer preamp.
Old 18th October 2013
Lives for gear

Exciting stuff! I really would like to try a pair of these. How about you just trade me straight across for a couple 512c's?
Old 18th October 2013
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Ribbonmicguy's Avatar
Bravo Jeff!
Old 19th October 2013
Gear Nut

Originally Posted by AdamNewman View Post
I'm starting a "My wife hates Jeff Steiger" support group if anyone is interested.

Post of the day!!

Old 19th October 2013
Gear Guru
drBill's Avatar
Sweet Jeff! Congrats. Makes me wish for more slots and more $$$.
Old 19th October 2013
Gear Guru
RoundBadge's Avatar
Thumbs up

having owned the original Heider pre's[and stupidly sold them] I will say these are going to be special!!
Old 19th October 2013
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andrewj's Avatar
Looks promising
Old 19th October 2013
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nickelironsteel's Avatar

Ugh great now i gotta get rid of 10x 521c to get those
Old 19th October 2013
Wow, nice work! Looking forward to hearing it!
Old 19th October 2013
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jsteiger's Avatar
Originally Posted by AdamNewman View Post
I'm starting a "My wife hates Jeff Steiger" support group if anyone is interested.
I think my wife may have already started that club
Old 19th October 2013
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channelcat's Avatar

Originally Posted by jsteiger View Post
I think my wife may have already started that club
My wife will be joining once I have disposable income again. Jeff (and Rack-N-Roll) will be getting most of it!

Jeff, do you anticipate using the Chicago area manufacturing company you referenced above for any other products (LC53A, 553, modular console, etc)? Just curious.

If you ever need a spare set of hands, just drop me a PM. I'm just over in Homewood. I'll gladly help out taking inventory or picking and packing orders, if it frees you up to focus on getting the console into production!


Old 19th October 2013
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ddageek's Avatar

Looks great Jeff now I know where my cash is going for a while ! Must have 8 of these !
Old 20th October 2013
Gear Addict
Noa's Avatar
Thank you Jeff!!
Old 21st October 2013
Here for the gear

Congratulations Jeff and good luck with the project!!
Been using the VP26 pair you built for me on every session I've had in the last 3 years and the new pres look like the perfect compliment and, I'm sure, just as sonically stunning.
Old 23rd October 2013
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Gravity8058's Avatar

"Go Jeff Go, Go Jeff Go..........."
Old 27th October 2013
Gear Head
Cabo Robo's Avatar

The Heiders are here and go on sale tomorrow. The first shipment will go fast so give us a call at Rack-N-Roll if your interested. $750ea

Rack-N-Roll Rob
Old 28th October 2013
The meter is a nice addition!
Old 29th October 2013
Here for the gear

Thanks Rob for letting me try the Heider man. I am buying it. Jas
Old 29th October 2013
Gear Head
Cabo Robo's Avatar

No problem. We will always let you demo any thing we have in stock. The Heider is raising a lot of eyebrows this week.

Old 3rd November 2013
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mike vee's Avatar
wow nice!

how would this sound on vocals?
Old 3rd November 2013
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jsteiger's Avatar
Originally Posted by mike vee View Post would this sound on vocals?
The Heider kills on vox. With the combo of the HiZ switch and the Pad, there are 3 different input impedance settings possible and they change tonally a noticeable amount. That is not to even mention the different combo's of preamp gain/fader settings.

I am just getting back from a week in Nashville where we captured some vid and will have some wav files for download. We have a female vocalist on my vintage 251 thru the FD312 and a male thru a MicRehab modded CV4 thru the FD312. For the dude, we forced him to sang the same line thru the 3 dif input Z settings. He can no longer comment here but the engineer who had us over can. We also did the same 3 input Z settings on stereo mic'ed dobro with the incomparable Randy Kohrs laying down some sick licks. It will be a little bit before we have all the files together but it is in the works. In the meantime, maybe Sal will chime in.
Old 3rd November 2013
Lives for gear
jsteiger's Avatar
Heider FD312 male vox clips

So, as previously mentioned, I was in Nashville last week and had the pleasure of hand delivering the first batch of Heider FD312 pre's to Rob at Rack-N-Roll. Throughout my week there, I was able to visit many studios to personally demo the FD312 as well as visit while Rob and Tom captured some great video interviews of current users. We will have many cool things to watch, listen to and download coming out over the next few weeks.

One of my stops was to hang with Sal Oliveri at his overdub studio, The Ice House in Franklin TN. Internet problem-child John Kennedy also came by to grace us with his sheer presence and vocal sangin' ability. In running thru the options on the Heider FD312, we of course chose to record some clips for comparisons. There are 3 wav files in the zip. The mic was John's CV4 that has been modded and hot rodded by the mic magus Shannon Rhoades of MicRehab. The A/D was the Avid HD Omni. The 3 different preamp settings are listed in the file names. In Sal's room on his Proacs, we all thought the "+HiZ" was the best sounding version. Of course there was no music bed but you will at least get the idea of how versatile the combination of a few pushbutton switches can be. The Fader was at 0 for the first 2 clips and +4 for the "+HiZ+Pad" version. We also increased the preamp gain to help make up for the Pad attenuation. Increasing those 2 settings is also part of the increased color. I think it really shows a wide swing of possible options. Many thanks to both Sal and John!

JK-CV4-FD312 clips
Old 6th November 2013
Gear Head
Cabo Robo's Avatar

I will have some Kick/Snare clips later on this week as well. People have been loving them for this application.
Old 16th November 2013
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jsteiger's Avatar
More clips for download

I have a few more Heider FD312 clips up to listen to. These are of Randy Kohrs on a resonator guitar mic'ed L/R with Peluso P-28's to a pair of FD312's to Apogee 16x converters. If you are like Scott and myself, you will find yourself paying more attention to the playing than the way the playing was captured.

We did the same 3 preamp settings as we did on the JK vox. They are labeled in the file names.

Here are the 48K clips. (These were created from the 96K files with PT's internal SRC)

And here are the hi rez 96K clips.

Cheers, Jeff
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