Symphony Desktop: Apogee Alloy Mic Preamp Emulation

Question: What hardware preamp was the AP-66 modeled after?

Answer - The AP-66 is modeled after a vintage Neve 1066 with “round-can” Marinair input transformer. Does this version of the input transformer sound “better” than the later rectangular version in the 1073? We’re not making any claims here, but we tried a few different modules (1066s, 1073s) and we chose this one to model.

Question: What makes your Neve mic preamp emulation different?

Answer - The big differences start in the analog domain: First, the circuit architecture of our Advanced Stepped Gain mic preamp is quite similar to that of a Neve. A Neve has a big red gain switch while the Apogee mic pre has a digitally-controlled analog gain switching module, but they operate in a very similar way. This allowed us to more faithfully reproduce the 20 to 80 dB gain structure of the Neve without a -20dB pad or additional digital trims (like other emulations have), just a gain knob and an output fader. We even discovered that when we pushed our circuit to 80 dB of gain, it exhibited a gradual high-end rolloff very similar to the Neve.

Next, we took our decades of experience with Soft Limit (an Apogee feature first introduced with the AD-500 in 1986) to create an analog circuit that shapes transients as the circuit is pushed into an overdriven state.

Finally, we added a switchable impedance feature to match the input impedance of our mic preamp to the two impedance values available on a vintage Neve preamp.

With these three innovations, a significant part of the mic preamp emulation is done in the analog domain, for a richer and more authentic result.

Of course, after the A/D conversion stage, on-board DSP is applied to precisely refine the emulation throughout the entire gain range. That’s Apogee Alloy, the fusion of analog and digital processing for a result that’s stronger than the components.

Question: How do I get started with the AP-66 mic preamp emulation?

Answer - When you first open the AP-66, the Input Gain and Output level are set so you’ll experience some saturation with many typical input sources. Raise the Input gain for more saturation, then adjust the Output level for a proper recording level.

Here’s a way to easily experience the entire range of our Neve emulation from subtle warming to full-on distortion while maintaining a relatively consistent output level:

1. Choose the AP-66 mic preamp emulation on the touch screen by tapping the IN1 button until the Settings view is displayed.
2. Tap Preamp, then choose AP-66, then tap the “X”.
3. Tap the IN1 button to display the Overview view.
4. Set Output Level to 0dB.
5. Input the signal to be recorded, and set Input Gain for a proper recording level. The meter should display an average level around -16 to -12 dBFs, with -6 dbFs peaks.
6. Tap GL (Gain Link) - now, as the Input Gain is raised, the Output Level lowers to compensate. 
7. As you increase the Input Gain, you’ll hear more and more saturation, then an overdriven sound, and finally very audible distortion. Experience to discover the effect that best suits your creation!

Question: What does the IMPD button do on the AP-66 model?

Answer - The IMPD stands for impedance, and the button alters the input impedance of the physical mic preamp circuit, similar to the Impedance switch found on Neve modules. When Lo-Z is on, input impedance is 300 ohms; when Lo-Z is off, impedance is 1200 ohms.

The impedance setting usually has a pretty subtle effect on the audio, but can have the most pronounced effect when lower impedance ribbon mics are connected.

Question: What hardware preamp was the AP-57 modeled after?

Answer - The AP-57 is modeled after a highly modified Ampex 601 tube preamp, part of a suitcase recording system from the late 1950s. The specific hardware unit used for modeling included the optional input transformer, a custom input attenuator and other custom tweaks.

Our AP-57 mic preamp emulation reproduces the complete experience using a 50s tube mic preamp - the larger-than-life sound, the rich harmonics, and the rapid onset of distortion, especially when using high-output large diaphragm condenser microphones!

If you have a 50s tube mic pre, you probably have an in-line attenuator or two just to be able to record with a condenser mic without overloading the mic pre input. Then again, if you’re looking for a warm but present distortion, the 601 preamp gets you there quickly. 

With our AP-57 emulation, you’ve got this choice as well - start with no pad, turn up the gain, and bask in the thick harmonics! If you’re barely cracking the Input gain but getting too much, engage the -20 dB pad - you’ll be able to increase the gain with less distortion. 

Once you’ve determined the pad setting, tap GL (Gain Link) to couple the Input Gain and Output Level controls to work together. The AP-57 emulation offers more extreme sounds than the other mic preamp emulations, so approach it with a creative mindset!