The eight reverb chambers built under the parking lot of the Capitol Records building in Los Angeles are some of the most highly revered, and closely guarded, environments for generating natural reverb in the commercial studio world. Capitol has never given permission for impulse responses (IRs) to be made of the chambers, so the only way to get that specific sound on your recordings has been to book time at Capitol's studios in the same building... until now!
Universal Audio were given access to the Capitol chambers to analyze the spaces, take IRs, and then combine those with additional algorithmic modeling in what UA calls "Dynamic Room Modeling" to come up with four chambers in a single UAD-powered plug-in called, not surprisingly, Capitol Chambers. They also worked closely with Steve Genewick, Capitol staff engineer and right-hand man to the renowned Al Schmitt on many of the records he has produced at Capitol, for ensuring the proper and most broadly useful microphone positions.
The interface for the UAD plug-in couldn't be more intuitive; starting at the top, there are four buttons to select from the chambers with an associated illustration of the space below these. Under the image are the four mic choices for each chamber, followed by a slider to set the decay time of the space (moving the mics closer to or farther from the speakers in the chamber). So much easier than running down to the basement, into the chamber, moving the mics, and then back to the control room to gauge if you like the sound (to say nothing of also having to be in L.A. and book one of the rooms at Capitol!). Changing the mic selection or decay time mutes the reverb output of the plug-in; to remind you of this, the door in the image of the chamber animates showing that the room is open for adjustment; also, the Capitol Tower logo on the top of the UI blinks indicating that the plug-in is calculating the new setting – cute, but also a handy reminder.
Next in the parameters are a row of EQ knobs with a high-pass filter that ranges from 80 to 750 Hz (the de-mud knob!) as well as an Off position to bypass the filter entirely, a bass knob at 125 Hz, mid at 500, and a treble knob at 5 kHz. These last three can boost or cut by 10 dB. At the bottom of the UI, there is a Mix control with a Wet Solo button next to it for when you're using the Capitol Chambers in a send/return Aux configuration with the output 100% wet, and finally a Width knob that varies the output from mono (at 0%) to the full stereo picture of the chamber at 100%.
Each of the four chambers has a specific pair of loudspeakers which are not variable between them, but the four mic choices are available within each chamber. This gives more tonal variation and flexibility beyond just being able to move the mics within the space; as UA demonstrated in their Ocean Way Rooms [Tape Op #128] plug-in, the mic choices go a long way in shaping the sound one can achieve with these reverbs. The mics are a pair of Altec 21D small-diaphragm omni tube condensers, RCA 44-BX ribbons (figure-8), Shure SM80 small-diaphragm omni condensers, and a pair of Sony C-37A cardioid tube-condensers. These are perfect choices for providing the broadest palette of pickup within four pair of microphones.
In use, I find myself gravitating to the Capitol Chambers when the music has the space for it; these are dense, complex sounding reverbs and really need room in the music to be felt properly. I love them on female vocals where I want to evoke a sense of that timeless quality the classic records from the ‘50s and ‘60s can create. I also used two instances of the chambers as my only reverbs on an entire acoustic jazz album by the Seattle electro-swing band Good Co – one instance was used for sending varying amounts of the instruments to while the other was exclusively for the vocals. The Capitol Chambers didn't timestamp the music to a specific time or place, but helped the instruments feel like they all occupied the same room while the vocals had a similar character without being cluttered out by the instrumental reverb.
If you are a UAD user I wouldn't hesitate adding the Capitol Chambers to your plug-in toolbox, but if you're unsure, they offer a fully-functional demo on the UA website.