History of Universal Audio

Founded in 1958 by Bill Putnam Sr., Universal Audio has been synonymous with innovative recording products since its inception. A favorite engineer of Frank Sinatra, Nat King Cole, Ray Charles and more, the late Bill Putnam Sr. was a passionate innovator who is widely regarded as the father of modern recording — with many of his legendary studio and equipment designs still in use today.

Specifically, Putnam was the inventor of the modern recording console, the multi-band audio equalizer, and the vocal booth, and he was the first engineer to use artificial reverberation in commercial recording. Alongside his friend Les Paul, Putnam was also involved in the early development of stereophonic recording.

Putnam, a natural entrepreneur, started three audio product companies during his long career: Universal Audio, Studio Electronics, and UREI. All three companies built equipment that remains widely used today, decades after their introduction, including the ubiquitous LA-2A and 1176 compressors, and the 610 tube recording console. The 610 console in particular stands as one of the most beloved designs in audio history, used to record everyone from Sinatra to the Beach Boys to Van Halen’s eponymous debut. It was the first to have each channel on individual modular strips for ease of maintenance, a design that is still in use today by boutique consoles.

Modern History of Universal Audio

Universal Audio was re-founded in 1999 by Bill’s sons, James Putnam and Bill Putnam Jr., with two main goals: to faithfully reproduce classic analog recording equipment in the tradition of their father; and to design new digital recording tools in with the sound and spirit of vintage analog technology.

The first products released by the re-founded Universal Audio were the 1176LN and LA-2A. In making their versions of these legendary pieces of gear, Universal Audio has taken great care to manufacture a compressor/limiter that original founder Bill Putnam Sr. would have been proud of. Throughout the development of these products, UA’s philosophy has remained clear: Stay true to the original. There are good reasons why certain pieces of gear have become classics, and they wanted to make sure that they captured the feel and sound of the original 1176LN and LA-2A accurately.

Shortly after Universal Audio was re-founded in 1999, the LA-2A and 1176LN were reissued with a design true to the original.

Universal Audio employs the world’s brightest DSP engineers and digital modeling authorities to develop their award-winning UAD Powered Plug-Ins platform. Featuring the most authentic analog emulation plug-ins in the industry, the UA DSP gurus work with the original hardware manufacturers — using their exact schematics, golden units, and experienced ears — to give UAD plug-ins warmth and harmonics in all the right places, just like analog.

In developing UAD plug-ins, UA’s engineering group undertakes a thorough physical modeling of classic audio hardware — “rebuilding” vintage analog gear in the digital world, component by component. That’s how UAD plug-ins replicate the exact, sometimes quirky, behavior of analog hardware — bringing its rich, three-dimensional sound and harmonics “in the box.”

From serious home recordists to multi-platinum mix engineers, UAD Powered Plug-Ins have been winning over audio professionals for more than 10 years. The reason is simple; no other plug-ins so faithfully capture the sound and behavior of classic analog equipment — from rare compressors and equalizers, to vintage reverb processors and tape machines.

UAD plug-ins are meticulous component-level recreations of highly sought after analog and digital audio gear. It was immediately apparent that such detail-oriented models would require large amounts of processing power. DSP accelerator hardware was adopted to provide consistent and repeatable instances of plug-ins while remaining independent of computer clock cycles and RAM. This allows us to create as intense an emulation as possible that can still run on the least powerful supported computers.

Apollo Overview

Apollo was designed and conceived to provide a near-zero latency solution to record audio. Starting with its high-quality analog I/O, Apollo’s superior sonic performance serves as its foundation. This is just the beginning however, as Apollo products are the only audio interfaces that allow you to run UAD plug-ins in real time. Want to monitor yourself through a Neve console channel strip while tracking bass through a classic Fairchild or LA-2A compressor? Or how about tracking vocals through a Studer tape machine with some added Lexicon reverb? With UA’s growing library of UAD plug-ins, the choices are limitless.

Apollo features Unison-enabled mic preamps (except Apollo x16), letting you track through exacting mic preamp emulations from Neve, API, Manley, Helios, SSL, and Universal Audio. A Universal Audio exclusive, Unison technology nails the tone of these sought-after tube and solid state mic pres — including their input impedance, gain stage “sweet spots,” and the component-level circuit behaviors of the original hardware.

The secret to Unison is its hardware-software integration between Apollo’s mic preamps and its onboard DSP Acceleration. Simply place a Unison preamp plug-in on your mic input in Apollo Console software, and it physically reconfigures the Apollo interface’s input impedance — so you can tap into the classic sounds of the world’s most recorded mic preamps.

Apollo and Arrow are further enhanced by adding Unison technology to front-panel Hi-Z instrument inputs, giving you dead-on impedance and gain matching for new guitar amplifier and stompbox models.

Thanks to Apollo Expanded software, users of any Thunderbolt-equipped Apollo interface can combine up to four Apollos and six total UAD-2 devices — adding I/O and DSP as your studio grows. Apollo Expanded also provides seamless integration with previous generation Apollos over Thunderbolt.

With thousands of hit songs and hundreds of Grammy-winning albums under their belt, Apollo interfaces are no strangers to tracking stellar-sounding records. To improve on the previous generation Apollo interfaces’ class-leading audio conversion, UA engineers obsessively auditioned the latest A/D and D/A converters — ultimately pairing elite-class 24-bit/192 kHz converters with all-new analog circuitry for an ultra-pristine signal path.

The Apollo X series also introduces new Dual-Crystal clocking — featuring dedicated crystals for 44.1/88.2/176.4k and 48/96/192k sample rates — resulting in stunningly low jitter, measured at less than 10 picoseconds. This translates into pure, artifact-free recordings and solid stereo imaging you can trust.

All Apollos feature UAD-2 processing. This lets you run UAD plug-ins, whether you’re tracking in real time with channel strips from Neve, Manley, or API, or running high UAD plug-in counts when mixing in your DAW.

From the tube warmth of Pultec EQs on guitars to the musical tube limiting of the LA-2A on vocals, or the pump of a genuine 1176 or Fairchild 670 tube compressor on drums, your recordings will take a giant leap forward with a rich, three-dimensional analog sound that UAD plug‑ins provide.

Every Apollo comes with the Realtime Analog Classics Plus plug-in bundle. You not only get legendary compressors such as the Fairchild 670 and EQs like the Pultec EQP-1A, but also stunning guitar and bass amp emulations from Softube, and UA’s landmark 610-B Tube Preamp and EQ plug-in. Included plug-ins are: UA 610‐B, Marshall Plexi Classic Amplifier, Fairchild 670 Legacy, Teletronix LA‐2A Legacy, UA 1176LN Legacy, UA 1176SE Legacy, Pultec EQP‐1A Legacy, Pultec Pro Legacy, Ampeg SVT-VR Classic Bass Amp, Precision Channel Strip, Precision Reflection Engine, Precision Delay Modulation, UA Precision Enhancer Hz, Raw Distortion, and RealVerb‐Pro.

Users that wish to expand their UAD-2 plug-in library can visit the Universal Audio webstore. You’ll find Channel Strips, Compressors, Delay & Modulation, Equalizers, Guitar & Bass amps and stompboxes, Mastering utilities like saturators and stereo widening, and Reverb. Below is a sampling of what to expect.

Channel Strips:

Helios Type 69, Neve 1073, SSL 4000 E, Manley VOXBOX, API Vision, Neve 88RS, UA 610A and B, Century Tube

Compressors and Limiters:

API 2500, Manley Variable Mu, Fairchild 670 and 660, Teletronix LA-2A, 1176 Collection, Empirical Labs EL8 Distressor, dbx 160, SSL 4000 G Bus Compressor, elysia alpha, Neve 33609, Teletronix LA-3A, Tube Tech CL1B, elysia mpressor, Valley People Dynamite, Summit Audio TLA-100A, Precision Buss Compressor, Vertigo Sound VSC-2

Delay & Modulation:

Galaxy Tape Echo, EP-34 Tape Echo, MXR Flanger/Doubler, Brigade Chorus, Cooper Time Cube MkII, Studio D Chorus, A/DA Flanger, Korg SDD-3000, Dytronics Tri-Stereo Chorus, Dytronics Cyclosonic Panner, Eventide H910 Harmonizer, A/DA STD-1 Stereo Tapped Delay


Pultec Passive Collection, API 500 Series Collection, Manley Massive Passive, Brainworx bx_digital v3, Cambridge, Tonelux Tilt, Sonnox Oxford Dynamic, Maag EQ4, Harrison 32C, Trident A-Range, Dangerous BAX, Neve 1081, Massenburg MDWEQ5, Neve 31102, Millenia NSEQ-2, Sonnox Oxford, Tube-Tech

Guitar & Bass:

Fender ’55 Tweed Deluxe, Fuchs Overdrive Supreme 50, Marshall Plexi Super Lead 1959, Friedman Buxom Betty, Ampeg SVT-VR, Ampeg B-15N, ENGL Savage 120, Suhr PT100, Gallien-Krueger 800RB, Distortion Essentials, Friedman Collection, Softube Amp Room, Sound Machine Wood Works, Chandler Limited GAV19T, Fuchs Train II, Ampeg SVT-3 PRO, ENGL Amp Bundle, Marshall Legends Bundle, Eden WT800, Marshall JMP 2203, ENGL E646 VS Limited Edition, ENGL E765 Retro Tube, Marshall Silver Jubilee 2555, Marshall Bluesbreaker 1962


Manley Massive Passive, Chandler Limited Curve Bender, Precision Maximizer, Precision Limiter, Precision K-Stereo Ambience Recovery, Ampex ATR-102, Sonnox Oxford Inflator, Shadow Hills Mastering Compressor, Sonnox Oxford Limiter v2, Brainworx bx_masterdesk, Precision Multiband, Chandler Limited Zener, Brainworx bx_refinement, Vertigo Sound VSM-3 Mix Satellite, Brainworx bx_saturator v2, Precision EQ

Mic Modeling:

Townsend Labs Sphere, Ocean Way Microphone Collection, Bill Putnam Mic Collection


AKG BX20, Lexicon 224, AMS RMX16, EMT 250, DreamVerb, EMT 140, Ocean Way Studios, Pure Plate

Special Processing:

Moog Multimode Filter, Oxide Tape Recorder, OTO Biscuit 8-bit Effects, Studer A800, Antares Auto-Tune Realtime, Little Labs Voice Of God, SPL Transient Designer, Brainworx bx_subsynth, Precision De-Esser, Thermionic Culture Vulture, FATSO Jr/Sr, Little Labs IBP, SPL Vitalizer MK2-T, Sonnox Oxford Envolution, Precision Enhancer kHz/Hz

Model Comparison

All Apollo and Arrow interfaces share the same latency figure. Whether USB, Firewire, or Thunderbolt, the basic premise is identical: tracking in real time with UAD-2 plug-ins and near-zero latency. No other audio interface features internal DSP with a 90+ plug-in library that is useable in both tracking and your DAW of choice. Apollo began on Firewire when it was the protocol of choice for multi-channel recording and mixing. Firewire provided enough bandwidth for both audio and UA’s plug-in architecture while supporting both Mac and Windows. Then Thunderbolt emerged and that was adopted as a more robust and powerful protocol that eliminated the bottlenecks of Firewire. Unfortunately, Windows did not support audio over Thunderbolt from the beginning, so UA opted for USB 3 for a PC specific Twin USB. While USB 3 is fully capable of meeting their basic spec, it doesn’t allow for some of the flexibility that Thunderbolt has. With Thunderbolt, you can link up to four Apollos and two UAD-2 DSP Accelerators. This scalability means your Apollo system can grow as your studio and needs change. If an Apollo Twin is connected into the Thunderbolt chain it automatically becomes a remote volume control for your Apollo rack master unit. Speaker switching and Talkback can also be initiated from Twin MkII units. All Apollos would automatically lock together via wordclock star distribution over Thunderbolt. Eventually Windows opened up audio into their Thunderbolt implementation and UA released a Windows driver shortly thereafter. As of today, Thunderbolt 1/2/3 Mac or PC computers are compatible with Apollo and Arrow interfaces.

For larger studios, an Apollo rack or racks is a perfect fit but for the smaller studio a desktop solution is best. Apollo Twin is ideal for this application. All inputs and outputs are easily accessible. Preamp and Monitor modes quickly switch between settings like Pad, Phantom, HPF, etc. The large central data wheel does triple duty as preamp gain, monitor volume, and headphone volume. All Twins have two Unison enabled mic preamps and direct inject inputs for instruments. They have four outputs which can feed up to two sets of stereo speakers or one set plus a headphone amp or other device.

Twin MkII’s built in Talkback microphone allows for easy communication between producer/engineer and musicians. Push it to latch on or hold it for momentary operation. You will quickly notice how much smoother sessions go when artists don’t have to constantly remove headphones to exchange conversation. The Talkback microphone can even be recorded to your DAW (with plug-ins if you want!) to keep notes or comical banter for the project.

Apollo Twins are available in three levels: Solo (1), Duo (2), and Quad (4). This indicates how many internal DSP chips are available for UAD-2 plug-ins. How many chips are inside determines how many plug-ins you can run simultaneously. To get a better idea of how many plug-ins you can fit, take a look at the UA UAD-2 instance chart here: https://help.uaudio.com/hc/en-us/articles/215262223

Note that all percentages are assuming a 44.1kHz sample rate and these values may decrease at higher sample rates. How much DSP you need is directly related to your application. Are you tracking rappers or singer/songwriters with a single acoustic guitar? A Solo may be sufficient. Are your tracks piling up and you need to initiate lots of plug-ins in your mix? A Duo is probably a better choice. Are you using the ADAT input for an external multi-channel mic preamp to track full bands or producing massive EDM mixes with tons of plug-ins? You should think about a Quad. The inputs and outputs between all three are identical, so it’s more about how much plug-in processing you require.

If you’re recording full bands, you need an Apollo rack. The more obvious reason is more inputs and outputs and more preamps (Apollo x8, x8p, 8 Quad) but there are lots of other points to consider. Apollo racks differ from Twin and Arrow in the following ways:

  • 8 Virtual Paths versus 4 on Twin
  • ADAT Output as well as Input vs. only Input on Twin
  • Flex Routing for direct input to output patching
  • Assignable FCN switch (Dim, Alt 2)
  • Two Thunderbolt ports for additional devices (UAD-2 Satellite or computer peripheral)
  • 3 sets of stereo monitors capability vs.2 on a Twin
  • 4 cue mix busses for musicians vs. 2 on a Twin
  • More outputs for a summing mixer or headphone amp distribution
  • Additional ADAT inputs and outputs to support SMUX and high sample rates
  • Wordclock in and out
  • SPDIF coax I/O (on Apollo x6 and only) with optional control room output mirroring

This leads us to our new rackmount Apollo X series. All Apollo X racks now contain six DSP plug-in processing chips (Hexa for six). A/D and D/A converters are an all new design with increased dynamic range from previous models and Dual-Crystal clocking for stunningly low jitter. Other new features include a built-in Talkback mic and selectable +24 or +20dBu operation for easier compatibility with high-end gear. Surround sound modes up to 7.1 will be part of a release in late 2018. This will give individual speaker level calibration, SPL values for control room, and mute/solo per speaker.


ArrowApollo Twin MkIIApollo Twin USBApollo x6Apollo x8Apollo x8pApollo x16Apollo 8Apollo FireWire
User ProfileTouring producers and musicians, podcasters, recording hobbyistsRecording musicians, project studio owners, bedroom producersPost-production professionals, electronic music producersRecording musicians and engineers, project studio ownersRecording musicians and engineers, project studio ownersProfessional engineers and studio facilitiesRecording musicians and project studio ownersRecording musicians and project studio owners
CompatibilityMac / WindowsMac / WindowsWindows OnlyMac / WindowsMac / WindowsMac / WindowsMac / WindowsMac / WindowsMac / Windows
ConnectivityBus Power via Thunderbolt 3Thunderbolt 1 or 2USB 3Thunderbolt 3*Thunderbolt 3*Thunderbolt 3*Thunderbolt 3*Thunderbolt 2FireWire 800
Host Ports111222222
Realtime UAD ProcessingYesYesYesYesYesYesYesYesYes
DUO (2)
QUAD (4)
DUO (2)HEXA (6)HEXA (6)HEXA (6)HEXA (6)QUAD (4)QUAD (4)
Unison Mic Preamps22224844
Unison Hi-Z Inputs11122222
Digital I/O8 ADAT IN
(optical TOSLINK)
(optical TOSLINK)
8 ADAT (optical TOSLINK); 2 S/PDIF8 ADAT (optical TOSLINK); 2 S/PDIF8 ADAT (optical TOSLINK); 2 S/PDIF2 AES/EBU8 ADAT (optical TOSLINK); 2 S/PDIF8 ADAT (optical TOSLINK); 2 S/PDIF
Monitor Outputs2 TRS2 TRS2 TRS2 TRS2 TRS2 TRS2 XLR2 TRS2 TRS
Headphone Outputs1 Stereo1 Stereo1 Stereo2 Stereo2 Stereo2 Stereo2 Stereo2 Stereo
Monitor ModesStereoStereoStereoStereo to 5.1Stereo to 7.1Stereo to 7.1Stereo to 7.1StereoStereo
Alt SpeakersNoNoNoUp to 2 StereoUp to 2 StereoUp to 2 StereoUp to 2 StereoUp to 2 StereoNo
Built-in Talkback MicNoYesNoYesYesYesYesNoNo
Included UAD plug-ins141414161616161616
MSRP (USD)$499$699 / $899 / $1,299$899$1,999$2,499$2,999$3,499$1,999$1,799
* Thunderbolt 2 compatible with Thunderbolt 2 to 3 adapter


UAD-2 DSP Accelerators

If your mixes are getting bigger than your Apollo’s DSP can handle, you can add a UAD-2 DSP PCIe, Thunderbolt, or Firewire Satellite to increase plug-in power. Adding a UAD-2 DSP Accelerator will allow you to initiate more plug-ins in your session. It’s as simple as connecting a Satellite over Thunderbolt to an Apollo rack, Twin, or Arrow. UAD-2 DSP Accelerators are available in Quad (4 DSP chips) and Octo (8 DSP Chips). They are also available as a Core, Custom, or Ultimate bundle. A Core package includes the Analog Classics Plus plug-in bundle, while Custom packages include the Analog Classics Plus bundle and your choice of any three individual UAD plug-ins at registration. The Ultimate 6 is UA’s flagship package and includes all 95 UA-developed plug-ins up to and including UAD software 9.4.

*The Ultimate 6 package includes 95 UA-developed plug-ins up to and including UAD Software v9.4. Does not include any Direct Developer (3rd party) plug-ins, nor plug-ins released after UAD software v9.4.