Capitol Chambers Manual

In this article

Get the sound of the world's finest echo chambers.

From Ray Charles to Frank Sinatra, Beck to Muse, the underground spaces below the iconic Capitol Tower in Los Angeles, have provided decades of gorgeous hi-fi ambience that is simply unmatched. After years of R&D and close collaboration with Capitol Studios, Universal Audio proudly presents the Capitol Chambers plug-in, a startling end-to-end recreation of the most popular echo chambers ever created.

  • Record and mix with the world's only authentic plug-in emulation of Capitol Studios' prized underground echo chambers

  • Add dense, natural reverberation to vocals or drums far beyond plate, digital, or simple convolution reverb

  • Create new sounds by repositioning Capitol Chambers' microphones using UA's Dynamic Room Modeling

  • Audition current and historical chamber configurations, plus all new setups
    Harness the chamber's entire signal chain including amplifiers, speakers, custom preamps, and mics

  • Quickly pull up presets from legendary Grammy-winning engineers of Ray Charles, Radiohead, Steely Dan, Madonna, and moreEasily Capture Iconic Echo

Easily Capture Iconic Echo

UA sourced historic technical diagrams from the early '60s to precisely emulate microphone/speaker setups inside Capitol's chambers, including the vintage omnidirectional Altec 21D mics and custom speaker/horn configurations and current "modern" configurations using omnidirectional Shure SM80s — all in their original hit-making positions.

Create with Unprecedented Ambience Control

Capitol Chambers' Position slider gives you next-level control over spatial and time response, allowing you to reposition the chamber mics. From the maximum distance stock positions, to direct speaker-to-microphone effects and proximity characteristics, Capitol Chambers can subtly thicken vocals or drums, or soak strings with the most natural, complex sounding reverb ever recorded.

Explore UA's Dynamic Room Modeling

Harnessing the same technology as UA's award-winning Ocean Way Studios plug-in, Capitol Chambers uses UA’s proprietary Dynamic Room Modeling technology, an exclusive combination of physical modeling and advanced measurement techniques. Whereas standard convolution reverbs only provide a sonic snapshot, Dynamic Room Modeling gives Capitol Chambers nearly infinite ambient possibilities.

Go Deeper Still

Beyond a vintage recreation, Capitol Chambers offers creative features for modern DAW workflows like Pre-delay, Dry/Wet mix, and Decay controls. A sweepable 80 to 750 Hz filter lets you minimize muddy bass going into the chamber, while Bass, Treble, and proportional Q Mid band lets you perfectly season the chamber's lush ambience.

Harness All-Star Artist Presets

The Capitol Chamber's plug-in features carefully crafted presets from a stunning roster of Grammy-winning engineers and producers, including the late Al Schmitt (Ray Charles, Steely Dan), Mark Linett (The Beach Boys, Los Lobos), Frank Filipetti (Madonna, Paul McCartney), Darrell Thorp (Beck, Radiohead), and many more.



Capitol Chambers



Operational Overview

Important underlying concepts for Capitol Chambers are presented in this section. For details about how to operate the specific controls, see Capitol Chambers Controls later in this chapter.

Hybrid technology

Capitol Chambers is neither a general impulse response (IR) convolution reverb nor a typical algorithmic reverb. Instead, Capitol Chambers utilizes breakthrough hybrid technologies, combining expertly sampled impulse responses with advanced algorithmic DSP techniques. Capitol Chambers is sonically superior in terms of overall model accuracy and dynamic customization. The Capitol Chambers plug-in is used to add ambience to existing sources just as you would with other reverb processors and methodologies.

Echo chambers

An echo chamber is the first technique used for adding controlled ambience to a recording. The chamber is simply an ambient space, such as a reflective room, that contains loudspeakers and microphones. To add ambience to an audio signal, the audio engineer sends audio signals to the loudspeaker(s) in the room. The ambience of the room is captured with the microphone(s), then the mic's wet signal is mixed with the original dry signal to create the final blended dry+wet sound.

The four most popular echo chambers at Capitol Studios (chamber numbers 2, 4, 6, and 7) are included in the plug-in. Each chamber has small variations in overall shape and total volume, a distinct speaker type and placement within the chamber, and a selection of microphones along with their placements. These attributes all contribute to the unique sonic response of each chamber.

The four chambers naturally provide a maximum reverberation time of approximately 5 to 9.5 seconds for full decay. Although not possible with the real physical chambers, UA's digital "beyond physics" Decay control allows these naturally occurring decay times to be reduced as desired, down to a minimum of one second.





The four available echo chambers


In addition to each chamber's acoustic design and speakers, the microphones and placements used to capture the ambient signals are a significant contributor to the frequency and spatial attributes of the chamber. The full signal path contains Capitol's custom-built electronics, including their in-house designed microphone preamps.

Capitol Chambers contains four different microphone pairs for stereo ambience capture. The microphone selections and default positions represent current, historical, or specially curated setups with help from Capitol staff and UA. Each pair can be used in any of the four chambers. The available microphones are described in the table below.




Altec 21D

Small diaphragm omnidirectional tube condenser microphone

Original installation; chambers 4 and 6 provide historically accurate configurations with a band limited frequency response

RCA 44

Figure-8 ribbon velocity microphone

Found in other popular chambers, provides a complex and colored yet controlled response, with strong proximity characteristics

Shure SM80

Small diaphragm omnidirectional condenser microphone

Current installation, in use since the early '80s, imparts a broad "reach" and a uniform frequency range

Sony C37A

Medium diaphragm tube condenser microphone in cardioid mode

Useful for an elevated, refined sound with moderate proximity characteristics

Microphones position

The position of the microphone pair relative to the source speaker can be dynamically adjusted with the Position control. As when recording with microphones in the physical realm, the mic position can have a significant impact on the sound that is captured.

The best way to explore the sonic possibilities of the Microphones Position control is by listening to the plug-in when it is applied on an individual source and MIX is set to 100% wet (or when WET SOLO is active).

As the mics are moved closer to the speaker, the room will sound tighter and the source will sound more present. Conversely, the room gets more diffused when the mics are farther away from the speaker. The Capitol Chambers modeling includes the proximity gain and bass buildup that occurs in the physical realm; the signal may be louder as microphones are positioned closer to the speaker.

The separation between a stereo microphone pair can subtly vary depending on the microphone pair selected and its Position setting.


In addition to each chamber's acoustic design and microphones, the speakers that send signals into the chamber are a significant contributor to the frequency and spatial attributes of the chamber. The physical size of the speakers and the space they take within the chamber is also a significant contributor to the chamber's sound and decay time.

Each chamber has a dedicated speaker pair. The speaker positions are fixed, and represent current, historical, or specially curated setups from UA and Capitol staff. As with Capitol Studio's original patch routing configuration, each chamber's dedicated speaker pair receives a mono summed input.

The speakers used in each chamber are described in the table below.





Altec 604 Duplex with JBL LE-175 horn and JBL crossover

Provides a rich, low-mid soundfield using an era-spanning, custom Capitol Studios component pairing


Altec A7 Voice of the Theatre with Altec 802 horn

"Al's chamber" is Capitol's most in-demand option, featuring the original installation movie theatre playback system, providing an incredibly balanced sound and Capitol Chambers' shortest natural decay


Altec 604 Duplex

Another original 1950s installation, with a coveted vintage hi-fi audio playback speaker system giving a warm, long decay


Tannoy System 8

In-demand chamber with a full range sound and the longest and most linear decay available, uses passive coaxial 8" mid-field speakers of English 1980s origin

Algorithmic recalculations

When the Chamber Select, Microphones Select, Microphones Position, or Decay controls are adjusted, algorithmic recalculations are executed by the plug-in. These recalculations cause a time lag before the new control values are heard. Additionally, sonic artifacts can occur while these recalculations are performed if audio is currently being processed by the plug-in.

Because there are extensive interdependencies within the plug-in, the specific time to complete the algorithmic recalculations depend on the control(s) being modified, the current sample rate, and the DAW buffer size.

Recalculation indicators

During algorithmic recalculations, visual indicators are active. These indicators signify that audio is not stable until the model recalculations are complete. The visual recalculation indicators that are active depend on which controls are being adjusted, as described below.

Note: When the Chamber Select, Microphones Select, Microphones Position, or Decay controls are adjusted, the new values are not completely heard until the Recalculation Indicators are inactive.

Chamber Select, Microphones Select, Microphones Position, Decay – When any of these controls are adjusted, the Capitol Chambers logo antenna flashes in yellow.


Flashing antenna during all algorithmic recalculations

Microphones Select, Microphones Position – When these controls are adjusted, the Capitol Chambers logo antenna flashes. Additionally, the door within the chamber view is open, alluding to an engineer entering the chamber to change or reposition the mics.


Open chamber door during microphone recalculations

DAW automation limitations

Load time and/or sonic artifacts during algorithmic recalculations can be an impediment if the specific controls listed in the table below are modified with DAW automation during mixdown. To avoid these impediments, adjusting specific Capitol Chambers controls with DAW automation during mixdown is not recommended.

If DAW automation must be used on these controls, it is recommended that only static snapshot automation (instead of continuous automation) be used. Additionally, static snapshot automation should be used only when the signal being processed is not audible. For example, automate only between musical phrases.

Parameter automation recommendations are described in the table below.

Capitol Chambers Parameter

Automation Recommendation

Chamber Select
Microphones Select
Decay Time

Not recommended
(time lag may cause sonic artifacts)

Microphones Position

Static snapshot automation between audio passages only (may cause sonic artifacts)

(all other parameters)

Continuous and static snapshot automation OK


Example bird's eye map of Position parameter – Chamber 4 with SM80

Accessing artist presets

Capitol Chambers includes presets voiced by prominent artists. The artist presets can be accessed via the plug-in's preset manager, your DAW's preset menu, or the preset manager in Apollo's Console.

Al Schmitt (Capitol Studios)

Jamie Lidell

Niko Bolas

Bassy Bob Brockmann

Joe Chiccarelli

Richard Chycki

Chris Dugan

Joey Waronker

Ross Hogarth

Damian Taylor

John Paterno

Steve Genewick (Capitol Studios)

Darrell Thorp

Mark Linett

Tom Elmhirst

Frank Filipetti

Mark Needham


Artists who have provided presets for Capitol Chambers


Due to its unique design requirements, Capitol Chambers is subject to increased latency versus other UAD plug-ins. The increased latency may be objectionable when tracking through the plug-in on individual channel inserts. This impediment also applies with Apollo/Arrow when using the Console application for Realtime UAD Processing.

This latency is not an issue when used in a typical effect send/ return configuration, nor during mixdown when latency is not a concern. When tracking live performances and the performer is monitoring through Capitol Chambers, using the plug-in a traditional effect send/return configuration where latency with time-based effects does not affect the monitored performance is recommended.

Tip: The reverb configuration illustrated below conserves processing power or UAD DSP when compared to inserting the same reverb plug-in on individual channels.


DAW signal routing with reverb plug-in using a traditional effect send/return configuration



Capitol Chambers Controls


Chamber select

The active echo chamber is selected with this row of four yellow buttons above the Chamber View. Click any button to choose the chamber. The active chamber's button glows, and its interior is displayed in the Chamber View.

Note: When Chamber Select is changed, the new value is not completely heard until the Recalculation Indicators are inactive.

Capitol_Chambers_190430 copy.png

Chamber Select buttons with Chamber 4 selected

Chamber view

The image beneath the Chamber Select buttons displays the currently active chamber with its speakers and the current microphones position.

Tip: Drag in the Chamber View to change the microphones position.

Microphones select

The stereo microphone pair used in the echo chamber are selected with these buttons. Click a button to choose a mic pair; the active mic's button is illuminated.

Note: When Microphones Select is adjusted, the new value is not completely heard until the Recalculation Indicators are inactive.


Microphones Select buttons

Microphones position

Position varies the distance between the microphone pair and the speaker, as well as the distance between the two mics. To change the mic position, drag the control slider or drag within the chamber view area.

Note: When Microphones Position is adjusted, the new value is not completely heard until the Recalculation Indicators are inactive.

When set to MAXIMUM, the microphones are in the original position as captured within the chambers at Capitol Studios. Values below MAXIMUM are adjusted algorithmically.

The aural effect of a mic position change most is obvious while listening to the chamber when MIX is set to 100% (or when WET SOLO is active).

Tip: Click the MINIMUM or MAXIMUM text labels to return the control to those values.

Capitol_Chambers_190430 copy 2.png

Microphones Position slider


The time between the dry signal and the onset of reverb is controlled with this continuous knob. The range is 0 to 250 milliseconds.

This control uses a logarithmic scale to provide increased resolution when selecting lower values.

Tip: Higher Predelay values can be useful for tracks where the clarity of the source should stand out before the reverb starts.


The power button enables/disables the plug-in. When enabled, the Power Lamp is illuminated. When disabled, the Power Lamp is de-illuminated and plug-in processing is disabled.

Tip: The UA logo also functions as a Power button.


Decay adjusts the reverberation time. Rotate the knob counter-clockwise to decrease the chamber's reverb time.

Note: When Decay is adjusted, the new value is not completely heard until the Recalculation Indicators are inactive.

When set to MAX, the decay time is the natural room decay as captured within the chambers at Capitol Studios. Values below MAX are adjusted algorithmically.

Tip: Click the MIN or MAX text labels to set the control to those values.


This knob controls a 6 dB per octave low cut (high pass) filter. The range is continuously variable from 80 Hz to 750 Hz. When set to OFF, the filter is disabled.

The Filter circuitry is on the microphone path for shaping the reverb return signal. Rotate the knob clockwise to reduce low frequency content.

Tip: Click the OFF text label to quickly disable the filter. Click the OFF label again to return to the previous value.


In addition to the low cut filter, three bands of boost/cut equalization are available. The EQ circuitry is on the microphone path for shaping the reverb return signal.

Each band has up to ±10 dB of continuously variable gain. Rotate a band knob clockwise from the center position to increase frequencies in the band. Rotate a band knob counter-clockwise from the center position to reduce frequencies in the band.

The Bass and Treble bands are Baxandall-style; the Mid band has proportional Q.

Tip: Click a band's frequency text label to reset its gain to 0 dB. Click the frequency label again to return to the previous value.

EQ Band

Band Center Frequency
Bass 125 Hz
Mid 500 Hz
Treble 5 kHz

EQ band center frequencies


Mix continuously sets the blend between the original dry signal and the wet reverberated signal. The available range is from 0% (no wet signal) to 100% (no dry signal).

Tip: Click the "0" or "100" text labels to quickly set these values.

This control uses a logarithmic scale to provide increased resolution when selecting lower values. When Mix is in the 12 o'clock position, the value is 15%.

When set to any value except 100% (or when Wet Solo is enabled), the dry portion of the signal is unprocessed.

Important: If Wet Solo is active, adjusting Mix will have no effect.

Wet Solo

Wet Solo puts the plug-in into 100% Wet mode. When enabled, the dry unprocessed signal is muted and the Mix control has no effect.

Wet Solo is typically used when the plug-in is inserted on an auxiliary effect return bus that is configured for use with channel aux sends, for 100% wet send/return processing. When the plug-in is inserted on a track, Wet Solo is typically disabled so the dry/wet mix control can be heard.

Wet Solo is a global (per plug-in instance) control. The switch state is saved within host DAW project/session files, but it doesn't change when a preset is loaded; the current state always overrides the preset state.

This feature allows presets to be properly auditioned without changing the Wet Solo setting. If Wet Solo is disabled when a preset is loaded, the dry/wet mix value in the preset is loaded (and heard) and Wet Solo remains disabled. If Wet Solo is enabled when a preset is loaded, the dry/wet mix value in the preset is loaded (but not heard) and Wet Solo remains active.

The global feature means preset settings are always loaded appropriately, whether the plug-in is loaded in a track insert (where Wet Solo is typically disabled and the mix control used instead), or in an aux return (where wet solo is typically enabled, defeating the mix control for 100% wet send/return processing).

Note (Pro Tools only): The Wet Solo setting is saved and loaded in presets when using the preset manager within Pro Tools. To audition presets without changing the Wet Solo state, the Load Preset function within the UAD Toolbar or the Apollo/Arrow Console must be used.


Width narrows the stereo ambience imaging. The range is continuously variable from 0% to 100%. At a value of zero, Capitol Chambers returns monophonic reverb. At 100%, the stereo signal has the natural fields as captured at Capitol Studios.

Tip: Click the "0" or "100" text labels to quickly set these values.

Note: When used in a mono-out configuration, this control cannot be adjusted.



Chambers construction at Capitol Studios

CAPITOL and the CAPITOL logos are trademarks of Capitol Records, LLC, registered in the United States, European Union, and other jurisdictions, and are used under license. Special thanks to Steve Genewick, Al Schmitt, and Niko Bolas.

Microphone and Speaker names are all trademarks of their respective owners, which are in no way associated or affiliated with Universal Audio or Capitol Records, LLC. These speaker names, descriptions and images are provided for the sole purpose of identifying the specific speakers studied during Universal Audio's sound model development and to describe certain speaker sound qualities and performance characteristics. Capitol Studios is a trademark used under license by Capitol Records, LLC.

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