LA-6176 Channel Strip Manual

In this article

The Analog Channel Strip of Your Dreams

la-6176_carousel_anim.gif

Experience Universal Audio's 70+ year analog heritage with a supercharged plug-in version of our flagship tube channel strip, the 6176. The new LA-6176 Signature Channel Strip plug-in gives you three iconic UA products in one: the 610 mic preamp, the 1176 Limiting Amplifier, and the LA-2A Leveling Amplifier.

Released in 2004, the hand-built 6176 has been the channel strip to stars including Coldplay, Adele, and Pharrell. Now you can get an entirely new UAD channel strip that puts decades of classic and modern vocal, guitar, drum, and bass sounds at the flip of a switch.

  • Record and mix with three of the most historically-significant pieces of analog gear ever made, in one elegant channel strip
  • Get the smooth harmonics and rich overdrive of a vintage UA 610 tube preamp on vocals and instruments
  • Instantly get the famous punch of the 1176, or the smooth warmth of an LA-2A, at the flip of a switch
  • Record in realtime with Apollo interfaces, putting three legendary processors in a single Unison slot

Plug in to the World's Most Famous Tube Preamp

Bill Putnam's 610 Modular Amplifier preamp was a milestone in audio history, introduced in the 1960's and used to record everyone from the Beach Boys, Ray Charles, and Johnny Cash to Coldplay and Adele. The LA-6176 plug-in features the modern 610-B circuit, giving you even deeper EQ controls for adding rich tube sound that works on everything.

Get the Legendary Punch of an 1176LN Limiter

The 6176 hardware is the first channel strip to pair our iconic 610 tube preamp with classic 1176 Limiting Amplifier. The 1176 is the compressor that defined decades of popular rock and pop music, from Led Zeppelin to Bob Marley to Beyonce. Its FET-based circuit delivers ultra fast response to guitar, bass, and drum transients making your tracks pop through the speakers.

Add Smooth LA-2A Tube Compression

Borrowing from our LA-610 MkII hardware channel strip, the LA-6176 plug-in packs iconic optical compression at the flip of a switch. In LA-2A mode, you'll get the same silky compression heard on classic vocal and instrument recordings for over 60 years. Plus, you can easily toggle between the LA-2A and 1176 modes to find your perfect sound.

Unison-Enabled for Realtime Recording on Apollo Interfaces

With an Apollo interface and Unison technology, the LA-6176 Signature Channel Strip makes you forget you're recording through a plug-in. You'll get all the unique impedance, gain stage sweet spots, and circuit behaviors of an original 610 tube preamp. And when you add in two legendary compressors — it puts three of our most famous analog circuits on a single Unison channel.

 

LA-6176 in 1176 mode

LA-6176 in LA-2A mode

 


 

Operational Overview

The LA-6176 Signature Channel Strip combines three UA hardware processors into a single channel strip plug-in. The processor combines the 610 vacuum tube microphone preamplifier with selectable input impedance, two gain stages, and flexible high and low shelving EQ, along with a choice of two dynamic processors: the 1176LN FET compressor or the LA-2A leveling amplifier.

Dynamics processor characteristics

The 1176 FET compressor has very fast attack and release characteristics, and can add aggressive edge and distortion at faster settings. This compressor really shines on drums and bass, and can add an aggressive edge to vocals, guitars, or any source that needs more grit and bite.

The LA22A optical leveling amplifier has a characteristically slow and complex program-dependent attack and release. The LA-2A is renowned for smooth, transparent compression on vocals, but you can use its warmth and roundness on any source.

Signal flow

Signal through the plug-in flows from left to right on the screen, from the 610 preamp section and EQ into the dynamics section. The EQ and dynamics processing can be independently bypassed.

Unison integration (Apollo only)

The LA-6176 Channel Strip plug-in features Unison technology for integration with the mic preamp hardware in Universal Audio's Apollo audio interfaces. With Unison interfaces, the ultra-transparent mic preamps inherit all of the unique sonics, input characteristics, and features of emulated preamps.

Note: Unison is active only when the plug-in is placed in the dedicated UNISON insert within UAD Console or LUNA. For complete details, see the Unison chapter within the UAD Console Manual.

With Unison, the hardware preamp adapts to the modeled preamp's physical input impedance. Combined with UA's transparent analog amplification, this provides the plug-in's full gain and tone range from clean to clipped — with broad, musical sweet spots in-between.

Presets

The LA-6176 Channel Strip includes presets voiced by prominent Universal Audio artists. Presets are accessed via the preset browser, or the plug-in host application's preset menu.

 


 

610 Preamp Controls

About Unison interactions (Apollo hardware only)

Some control descriptions begin with the "Unison Interaction" heading and include the Unison icon. Descriptions in these sections apply only when the plug-in is placed in the dedicated UNISON insert on an Apollo preamp channel within the UAD Console or LUNA applications. When the plug-in is used in standard (non-Unison) inserts in Console, or within a DAW, these descriptions do not apply.

Note: For complete details, see the Unison article in the [UAD Console manual].

Input & Impedance

The 610 hardware has mic, Hi-Z and line level inputs. When used with a DAW, the Input Select control switches between the "virtual input jacks" in the emulated preamps.

Note: You can switch freely between Mic and Line inputs, however the Hi-Z input is only available under Unison. The Hi-Z input is automatically enabled when using aUnison insert with an instrument plugged into the Hi-Z jack.

Tip: Click the text labels to change the settings.

Important: Use caution when switching from Line to Mic, as signal output levels can increase significantly (as they would with a hardware preamp).

unison-icon1.png

Apollo Unison Interactions

When the plug-in is placed in the dedicated Unison insert for the preamp channel within Apollo’s Console application or LUNA, the following behaviors apply:

  • Software and hardware controls are mirrored and bidirectional, and can be adjusted with the plug-in, Console/LUNA software, or Apollo's hardware INPUT switch.
  • When Apollo's Hi-Z instrument input is connected, the source switch is automatically overridden and the switch has no effect.

Line

When set to Line, it's as if the DAW signal is plugged into the line level input of the 610 hardware. Use the Line setting for cleaner sounds.

Mic

When set to Mic with 500 or 2.0K impedance selected, it's as if the DAW signal is plugged into the microphone input of the 610 hardware and approximately 30 dB of additional (unattenuated) tube gain is available. Since the incoming signal from the DAW is already at line level, use the Mic setting for more tube color, saturation, and clipping associated with overdriving the input.

Impedance

The Mic input can be switched to 500 or 2.0K Ohms and the Hi-Z input (Unison only) can be switched between 47K and 2.2M Ohms. The different input impedances have subtle effects on the signal level and frequency response.

The previous impedance selection is recalled when switching between Mic and Hi-Z settings.

unison-icon1.png

Apollo Unison Interactions

When the plug-in is placed in the dedicated Unison insert for the preamp channel within Apollo’s Console application or LUNA, the following behaviors apply:

  • The hardware input impedance of the Apollo mic preamp or Hi-Z input is switched to match the value in the plug-in for physical resistive interaction.
  • Matching the microphone or Hi-Z instrument to the closest impedance value is generally recommended, but this parameter can be used creatively and will not harm equipment connected to the Apollo mic preamp or Hi-Z input.

Gain

The Pad and Gain parameters both control the signal level at the tube input stage. The Pad control is used to attenuate incoming signals for less coloration, while the Gain controls increase the signal level for more tube color.

The 5-position rotary Gain switch adjusts the signal level at the tube input stage, and also changes the distortion characteristics. The control attenuates the input signal by -10 or -5 dB, or adds +5 or +10 dB of gain. In the center "0" position, neither gain nor attenuation is applied.

Tip: Click the text labels to change the settings.

unison-icon1.png

Apollo Unison Interactions

When the plug-in is placed in the dedicated Unison insert for the preamp channel within Apollo’s Console application or LUNA, the following behaviors apply:

  • Software and hardware control is mirrored and bidirectional, and can be adjusted with the plug-in, Console/LUNA software, or Apollo's hardware PREAMP knob.
  • When Apollo is in Unison Gain Stage Mode, the control is outlined in orange, indicating it is available for hardware control.

Mic Input Pad

An additional -15 dB of attenuation is available for the Mic input via the Pad switch. Setting the switch to the up position attenuates the Mic signal at the tube input stage. In the down position, no attenuation is applied.

Note: Pad is not available for line or Hi-Z inputs.

unison-icon1.png

Apollo Unison Interactions

When the plug-in is placed in the dedicated Unison insert for the preamp channel within Apollo’s Console application or LUNA, the following behaviors apply:

  • Software and hardware control is mirrored and bidirectional, and can be adjusted with the plug-in, Console/LUNA software, or Apollo's hardware PREAMP knob.
  • When Apollo is in Unison Gain Stage Mode, the control is outlined in orange, indicating it is available for hardware control.

Polarity

This switch inverts the polarity (aka phase) of the signal. The signal polarity is inverted when the switch is in the up position. Polarity is normal when the switch is in the down position. Polarity inversion can help reduce phase cancellations when more than one microphone is used to record a single source.

Tip: Click the text labels to change the setting.

unison-icon1.png

Apollo Unison Interaction

When the plug-in is placed in the dedicated Unison insert for the preamp channel within Apollo’s Console application or LUNA, the following behaviors apply:

  • Software and hardware control is mirrored and bidirectional, and can be adjusted with the plug-in, Console/LUNA software, or Apollo's hardware ø switch.

Cut

This switch applies a 12 db/octave low cut filter at 75 Hz, to reduce low frequency rumble and noise. The cut is applied when the switch is in the up position.

unison-icon1.png

Apollo Unison Interaction

When the plug-in is placed in the dedicated Unison insert for the preamp channel within Apollo’s Console application or LUNA, the following behaviors apply:

  • Software and hardware control is mirrored and bidirectional, and can be adjusted with the plug-in, Console/LUNA software, or Apollo's hardware filter switch.

Level

Level (aka "the big knob") is used to control the signal level of the tube output stage of the preamp. Higher values add more coloration.

Tip: Click the label to return the knob to the default value.

unison-icon1.png

Apollo Unison Interactions

When Apollo is in Unison Gain Stage Mode, the following behaviors apply:

  • Software and hardware control is mirrored and bidirectional, and can be adjusted with the plug-in, Console/LUNA software, or Apollo's hardware PREAMP knob.
  • The control is outlined in amber, indicating it is available for hardware control.

610 Preamp EQ Controls

The EQ includes low and high shelf filter bands with selectable cutoff frequencies that can be cut or boosted by various amounts.

LOW Frequency

This switch determines the cutoff frequency (70, 100, or 200 Hz) of the low shelf EQ. This switch has no effect if the Low EQ Gain value is zero.

LOW Gain

This rotary switch determines the amount of boost or cut applied to the low frequency signal. Fixed values of ± 9, 6, 4.5, 3, or 1.5 dB can be selected. When set to 0 dB, the filter is inactive.

HIGH Frequency

This switch determines the cutoff frequency (4.5 kHz, 7 kHz, or 10 kHz) of the high shelf EQ. This switch has no effect if the HiGH EQ Gain value is zero.

HIGH Gain

This rotary switch determines the amount of boost or cut applied to the high frequency signal. Fixed values of ± 9, 6, 4.5, 3, or 1.5 dB can be selected. When set to 0 dB, the filter is inactive.

 


 

Dynamics Mode & Meter Controls

Mode

This switch toggles between the 1176 FET and LA-2A optical dynamics types. The plug-in's appearance changes when you switch between dynamics modes, revealing the layout and features of UA's 6176 (silver) or LA-610 (black) hardware channel strips.

Meter

The Meter switch allows you to choose the metering mode for the VU Meter.

In – Monitors the input level of the dynamics section (after the 610 preamp and EQ).

GR – Monitors the gain reduction amount applied by the dynamics processing.

Out – Monitors the output level of the plug-in after dynamics processing. If dynamics are bypassed, Out level is identical to In level.

 


 

1176 FET Compressor Controls

Attack

Attack sets the amount of time it takes the 1176 to respond to an incoming signal and begin gain reduction. The 1176 attack time is adjustable from 20 microseconds to 800 microseconds (both extremely fast).

The attack time is fastest when the Attack knob is in its fully clockwise position, and is slowest when it is in its fully counter-clockwise position. When a fast attack time is selected, gain reduction kicks in almost immediately and catches transient signals of very brief duration, reducing their level and thus "softening" the sound.

Slower attack times allow transients (or partial transients) to pass before limiting or compression begins on the rest of the signal. Note that the actual attack time varies slightly based on the selected ratio; lower ratios will maintain the fastest attack times.

Tip: Click the Slow or Fast text labels to set the control fully fast or slow.

Release

Release sets the amount of time it takes the 1176 to return to its initial (pre-gain reduction) level. The 1176 release time is adjustable from 50 milliseconds to 1100 milliseconds (1.1 seconds).

Note that the actual release time varies slightly depending on the program material.

The release time is fastest when the Release knob is in its fully clockwise position, and is slowest when it is in its fully counter-clockwise position. If the release time is fast, "pumping" and "breathing" artifacts can occur, due to the rapid rise of background noise as the gain is restored. If the release time is too slow, however, a loud section of the program may cause gain reduction that persists through a soft section, making the soft section difficult to hear.

Tip: Click the Slow or Fast text labels to set the control fully fast or slow.

Ratio

The Ratio knob determines the compression ratio of the plug-in. Limiting ratios of 20:1, 12:1 and 8:1 and 4:1 compression ratios are available. In addition, the control includes a 1:1 ratio, allowing you to use the 1176 amplifier section without any compression. The ALL setting recreates the "All Ratio" mode (also known as "All Buttons" or "British" mode).

In All Buttons mode the ratio goes to somewhere between 12:1 and 20:1, and the bias points change throughout the circuit, thus changing the attack and release times as well. The unique and constantly shifting compression curve that results yields a trademark overdriven tone that can only be found in the 1176. In All Button mode, distortion increases radically due to a lag time on the attack of initial transients.

Input

Input adjusts the amount of gain as well as the relative threshold. Rotate the knob clockwise to increase the compression amount.

Like the original hardware, the label values are arbitrary; the knobs are not calibrated to any particular dB values. Even when the Input knob is set to 0, signals can still pass into the processor and be compressed.

Note: Increasing Input can increase distortion.

Output

Output determines the final output level of the signal leaving the 1176. Once the desired amount of limiting or compression is achieved with the use of the Input control, the Output control can be used to make up any gain lost due to gain reduction.

To monitor the Output level, set the VU Meter switch to Out. The Output control does not affect the amount of compression.

Note: Increasing Output can increase distortion.

Mix

A blended output balance between the signal processed by the plug-in and the original dry source signal can be adjusted with the Mix control. Mix facilitates parallel compression techniques without having to create additional routings in the DAW.

When Mix is set fully counterclockwise ("Dry"), only the dry, unprocessed source signal is output. When set full clockwise ("Wet", the default value), only the wet, processed signal is output. When set to 50% (5 on the knob), an equal blend of both the dry and wet signals is output. The balance is continuously variable, and phase accurate, throughout the control range.

Tip: Click the Dry or Wet text labels to set the control fully dry or fully wet.

Filter

This switch engages a gradual, linear sidechain filter to the detector circuit. The switch is lit yellow when enabled. Engage this to noticeably increase low frequency punch.

Note: The sidechain filter only acts on the compressor's sidechain signal. While this filter can produce an audible change in dynamics behavior, it does not act directly on the audio signal.

 


 

LA-2A Leveling Amplifier Controls

Peak Reduction

This control sets the amount of signal compression by adjusting the detector threshold. Increasing the value lowers the threshold, and therefore increases the amount of compression. The available range is 0 dB (fully counter-clockwise) to -40 dB(fully clockwise).

Note: The knob values, which range from 0-100, are arbitrary and do not reflect any particular dB value.

Rotate this control clockwise until the desired amount of compression is achieved. To monitor the amount of Peak Reduction, set the VU Meter knob to GR. Peak Reduction should be adjusted independently of the Gain control.

When Peak Reduction is set to its minimum value, no compression (or limiting) occurs but the signal is still colored by the circuitry and the output level can be adjusted with the Gain control.

Gain

The Gain knob increases the output level by up to 40 dB to compensate for the reduced level that results from compression. Adjust the Gain control after the desired amount of compression is achieved with the Peak Reduction control. The Gain control does not change the amount of compression.

Note: The knob values, which range from 0-100, are arbitrary and do not reflect any particular dB value.

Comp/Limit

This switch sets the compression ratio of the leveler. When set to Compress, the compression ratio is approximately 3:1, and when set to Limit, the ratio is approximately infinity:1. However, the compression ratios are nonlinear and frequency dependent, so these figures are not absolute.

 


 

Bypass Controls

 

When the plug-in or Dynamics module is bypassed, processor usage is reduced. On the UAD-2 plug-in, if UAD-2 DSP LoadLock is inactive, UAD DSP usage is reduced.

EQ Bypass

This switch bypasses the EQ circuit when in the up position.

DYN Bypass

This switch bypasses the selected dynamics processor, without imparting any color from the dynamics circuitry.

Power

Use the Power switch to bypass or enable plug-in processing.

Tip: Click the lamp to toggle bypass.

 


 

LA-6176 History

UA 610

The 610-B (as found in the LA-6176) was inspired by the microphone preamp section of the original 610 console designed by UA founder, M.T. "Bill" Putnam, in 1960. The 610 custom consoles, which included the 610-A preamp and EQ modules, were the first consoles of a modular design. Although technologically simple compared to modern consoles, those 610 consoles possessed a warmth and character that kept them in demand for decades.

A prominent component of Putnams' United/Western Studios in Los Angeles, the 610 was used on many classic recordings by Frank Sinatra and Sarah Vaughan, as well as records like the Beach Boys' Pet Sounds and the Doors' LA Woman. The extensive live recordings made with Wally Heider's 610 "Green Board" include records by Duke Ellington, Elvis Presley, Johnny Cash (At Folsom Prison), Cream, The Who, The Grateful Dead, The Byrds, Jefferson Airplane, Booker T. & the M.G.s, Otis Redding, Eric Burdon and The Animals, Simon and Garfunkel, and The Jimi Hendrix Experience. The desk was then bought by Neil Young and has been used on his records ever since.

The 610 mic pre has an illustrious history associated with numerous landmark recordings of the past, but it is also widely used today in its modern incarnations (2-610, 6176, LA-610 MkII, SOLO/610 and more). The UA 610 is collectively UA's best selling preamp, and is still one of the best selling preamps in the analog preamp market.

UA / UREI 1176

The original Universal Audio 1176 was designed by UA founder Bill Putnam in 1966, and represented a major breakthrough in limiter technology: a true peak limiter with all-transistor circuitry and superior performance on all types of program material. The 1176's major selling point was its ultra-fast attack time – a mere 20 µS (.00002 seconds) at its fastest setting.

Several revisions of the unit were developed throughout the years. The initial 1176 was released in 1967. These "bluestripe" units' faceplates were made from brushed aluminum with a blue stripe that covered the meter area. In 1970 the familiar all-black 1176, the 1176LN, was released, boasting lower noise and increased linearity. The D and E revs from 1970 to 1973 are widely considered to be the best-sounding units, and these circuits are featured in UA's 1176 reissue and the 6176.

With its ultra-fast FET gain reduction circuit and overall flexibility and musicality, the 1176 has lent its character and punch to a long list of some of the greatest recordings in history.

Teletronix LA-2A

In the early 1950s, Jim Lawrence, a young electrical engineer from USC, joined Cal Tech's Jet Propulsion Laboratory (JPL), where he was assigned the task of developing optical sensors for the Titan Missile Program. Little did he know at the time that his work on this Cold War-era project would spawn the Teletronix® LA-2A Leveling Amplifier — one of the most iconic compressors in history. He combined a luminescent panel with photo resistors (whose impedance changes relative to light intensity), and sealed them in a vacuum-tube-sized metal canister.

This optical attenuator, known as the T4, is what gives the LA-2A the transparent, program-dependent optical compression that is revered by audio professionals worldwide to this day. The T4 optical attenuator in the LA-2A is both program and frequency dependent, allowing the compression ratio to vary greatly based on the source material, and lending the LA-2A its trademark smooth and transparent character.

In 1965, Jim Lawrence sold Teletronix to Babcock Electronics of Costa Mesa, California, and in 1967, Bill Putnam purchased Babcock's broadcast division, including the Teletronix brand. His company continued to manufacture the LA-2A, swapping the original gray faceplate with a silver one.

 

Universal Audio 6176 and LA-610 MkII Hardware

Articles in this section

See more