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Universal Audio UAD1

Plug-in DSP Card For PC By Martin Walker
Published October 2001


A new wave of dedicated DSP cards is helping computer musicians boost their plug‑in power. The latest to appear is Universal Audio's UAD1, which offers recreations of vintage compressors as well as a high‑quality reverb.

Even on today's fast computers, some plug‑in effects such as reverb and 'analogue' EQ still take a hefty chunk of CPU power. At the top end of the market, Digidesign's Pro Tools systems have long offloaded their plug‑in processing to dedicated DSP cards; and several manufacturers are now marketing cheaper DPS systems that are not tied to a particular host application or hardware platform. This is the approach taken by the TC Powercore (reviewed in SOS June 2001), Creamware's Pulsar XTC, and the subject of this review, Universal Audio's UAD1. All three offer transparent operation with any VST‑compatible host application, so you can carry on running Cubase VST, Logic Audio, or Nuendo exactly as before, but with the benefits of high‑quality plug‑ins which don't use up the host computer's CPU power.


For many musicians, the highlight of the UAD1 bundle will be Realverb Pro, a versatile, high‑quality reverb with an attractive graphic interfaceFor many musicians, the highlight of the UAD1 bundle will be Realverb Pro, a versatile, high‑quality reverb with an attractive graphic interface

The UAD1 DSP card is just seven inches long — about half the size of its competitors, which may be helpful if you have limited space in your computer. Since it neither needs nor has any I/O ports, the backplate is blank, and although there is provision for multi‑pin connectors on the circuit board, none were mounted on the review model. I n fact, there is remarkably little circuitry on the UAD1, apart from 4Mb of onboard RAM and a single 'secret' DSP chip fitted with a finned heatsink. Universal Audio are reticent about its origins, but do say that it's not made by either Motorola or SHARC, as used by TC and Creamware respectively in the Powercore and Pulsar XTC.

Despite all the claims of huge processing power relative to both native platforms and other DSP cards, it's tricky to provide direct comparisons when the same plug‑ins aren't yet available for each one. Even where similar models exist, they may scale their processing up or down along with the price, to suit each product. However, for what it's worth, Universal Audio claim that the UAD1 card is around 2.5 times more powerful than a Digidesign Mix Farm card [#Anchor‑Universal‑49575], and about twice as powerful as both the TC Powercore and Pulsar XTC. One more direct comparison that UA give does seem useful: you can run three instances of their Realverb Pro plug‑in on a Pro Tools TDM Mix 24 system, and eight of the Powered Plug‑In version on the UAD1.


The CS1 Channel Strip incorporates an EX1 five‑band parametric EQ and compressor, DM1 Delay Modulator, and RS1 Reflection Engine, all of which can be launched separately.The CS1 Channel Strip incorporates an EX1 five‑band parametric EQ and compressor, DM1 Delay Modulator, and RS1 Reflection Engine, all of which can be launched separately.

To run the UAD1 you currently need a PC running Windows 95, 98, or ME, and a VST host application such as Cubase VST, Logic Audio, or Nuendo. Installation on my PC running Windows 98SE was simplicity itself: the Plug and Play card was correctly detected, and there were just four driver files. The seven DLL files that interface with VST‑compatible applications need to be installed separately into your normal Vstplugins folder, while Universal Audio place a small Performance Monitor utility, User Guide and QuickStart manuals in PDF format in a separate folder. All in all, it took me just 10 minutes from opening the box to opening up Wavelab to try out the Powered Plug‑Ins. The only thing to watch out for is that the plug‑in presets on the CD‑ROM aren't copied across to your hard drive: you'll need to do this by hand.

It's important to point out that all the DSP cards mentioned run a different computing language to Mac and PC host computers, so you can't use their DSP power to run ordinary VST plug‑ins. Instead, each product ships with a bundle of specially written plug‑ins, and you can buy more from the original manufacturer or from third‑party developers, if they choose to support that particular DSP card. Universal Audio have been granted the trademarked name 'Powered Plug‑Ins' for their plug‑in format. In practice you won't notice any difference when launching them — the new options just appear on your existing list of VST plug‑ins, the only difference being that they take little or no overhead on the VST CPU meter.

Realverb Pro

Universal Audio manufacture expensive hardware recreations of the classic 1176LN and Teletronix LA2A compressors, but buyers of the UAD1 get virtual versions thrown in.Universal Audio manufacture expensive hardware recreations of the classic 1176LN and Teletronix LA2A compressors, but buyers of the UAD1 get virtual versions thrown in.

Universal Audio already have a good reputation for their 'vintage' analogue products like the 1176LN compressor (reviewed by Hugh Robjohns in SOS June 2001), and their recent acquisition of Kind Of Loud Technologies has brought in extra digital expertise, along with the highly regarded Realverb Pro software reverb for Pro Tools TDM systems. This has now found its way into the UAD1 bundle, along with digital recreations of UA's own 1176LN and Teletronix LA2A compressors.

As you might expect given its heritage, the sound of Realverb Pro is truly excellent: like all the best reverbs, its virtual acoustics become a part of the track rather than sounding 'pasted on'. It has rather more controls than many reverbs, along with an attractive graphic interface. You can select from a palette of room shapes and sizes, materials and thickness, and blend between two different room shapes/sizes or two different materials in real time.

There are 15 room shapes, ranging from basic types like cube, shoebox, and corridor to the more curvy cylinder, dome, and horseshoe, plus various springs and plates, while materials include brick, concrete, wood, marble and various types of glass, through to linoleum, carpet, and full drapes. This approach may sound like a gimmick, but each option is firmly based on acoustic measurements, and the results make perfect audio sense. The intensity, timing and placement of early reflections and late‑field reverberation can be separately adjusted, as can EQ, and you can even morph between two entire reverb presets in real time. This is an impressive plug‑in whose sound easily surpasses that of any native reverb I've heard to date.

Vintage Compressors


The two compressor plug‑ins provide exact graphic recreations of the real‑world machines' front panels — and rather than simply recreating the same transfer characteristics, UA have modelled the actual circuitry of each model, even including such factors as the hysteresis and core saturation of the output transformer. Like the reproduct ion hardware version reviewed in SOS June 2001, the digital recreation of the 1176LN is modelled after the D and E 'black face' versions of this classic compressor. With easy‑to‑use controls — Input and Output levels, Attack and Release times, switched Ratio, and a VU meter displaying gain reduction or output level — it proves, like the original, to be excellent for vocals and bass.

In its hardware form, the Teletronix LA2A Levelling Amplifier is an electro‑optical compressor design first introduced in the early '60s, with reproduction units currently retailing at about £3500. This has even fewer controls — a limit/compress mode switch that selects either infinity:1 or soft‑knee 4:1 compression ratios, output Gain and Peak Reduction (effectively threshold) rotary controls, and another VU meter, while the attack and release times are programme‑dependent, and determined in the original by the characteristics of a light and a cadmium sulphide photoelectric cell.

This design provides a very fast attack time of about 10 microseconds, and a two‑stage release with the initial part over at around 50mS and the rest determined by the cell's 'memory effect'. The result is extremely smooth control with very few artefacts, and once again the virtual version gave very musical results. Sadly I didn't have the originals alongside for comparison, but UA seem confident that those who do will be impressed.

The Channel Strip

EX1 is an equaliser/compressor. The EQ features five parametric sections with individual bypass. All provide ±18dB of swing over the full audio range of 20Hz to 20kHz, but while the middle one has a straightforwa rd Q control, the two on the left can also be switched into low‑shelf or high‑pass modes, and the two on the right can be used in high‑shelf or low‑pass modes. It certainly sounded sweet to me, and only took a tiny 4 percent of the DSP power. The compressor section incorporates elements from both the 1176 and LA2A simulations, with straightforward Attack, Release, Ratio, and Threshold controls.

RS1 Reflection Engine is designed to generate early room reflections to support sounds in a mix, when you don't need all the facilities of Realverb Pro. It has a choice of 22 reflection shapes, along with delay and size controls, and can also be coaxed to produce a wide range of other effects including echo, ping‑pong and multi‑tap delays, and gated reverb. DM1 Delay Modulator is capable of quite a range of effects, including comb filtering, chorus, flange, and echo and ping‑pong delays up to 300mS, and like all the other plug‑ins comes with a range of both mono and stereo presets, and takes about 3 percent of the CPU power. The CS1 Channel Strip (from top to bottom) combines the functions of EX1, DM1, and RS1 into one large panel.

Every parameter of each plug‑in can be automated, and UA have taken great pains to remove all zipper noise by smoothing, which makes automation of even reverb parameters feasible, for some bizarre acoustic effects. Audio quality is also maximised by providing hardware Ultra Dither at each audio stage. To give an idea of the amount of total processing power on offer, it's possible to run three Realverb Pro reverbs, 32 EQs, and 16 compressors simultaneously at 44.1kHz.

In Use

When I fired up Cubase VST and Wavelab to put the UAD1 plug‑ins through their paces, I generally found them no different to using any other plug‑ins. However, because of the way the UAD1 works, there are a few things to bear in mind. It's generally best to launch and keep its Performance Meter in its 'Always on Top' mode to keep an eye on the UAD1's DSP and RAM overhead, although it was well behaved when reaching 100 percent, and didn't fall over.

Although Cubase correctly releases all plug‑ins used when you open a new song, Nuendo doesn't, and so for the time being UA recommend closing Nuendo and then reopening it when changing sessions, as otherwise your UAD1 plug‑ins may remain open with no way to close them down. Due to technical issues involving the PCI buss, latency can also be an issue with DSP cards, and since Logic Audio doesn't currently support plug‑in delay compensation, tracks must be skewed by hand until Emagic release their next free update.

There are a few other 'known issues' mentioned in the Readme file, but the one that I found most annoying was some buzzy 'out of sync' distortion which can occur after the DSP gets momentarily pushed 'over the top' when running near maximum overhead. It can also occur with soundcard buffer sizes below 512 bytes, and even when changing Powered Plug‑ins (UA recommend choosing 'No Effect' before choosing a new one).

Sadly, although each of the plug‑ins worked perfectly in Wavelab, they refused to work without similar 'async' distortion when chained together in any combination, although I could chain them inside Cubase with no problems at all. I also occasionally got this same problem when reopening a Cubase song that used Powered Plug‑Ins. Although there are workarounds, this is a problem that I hope UA will solve fairly quickly.

Final Thoughts

If you're not currently happy with the quality of your native plug‑ins, or your CPU runs out of juice too quickly, you might find the UAD1 the perfect solution. Yes, you could use the £880 to buy some better quality plug‑ins and a faster CPU, but if UA's claims are correct you'd still not match the UAD1's processing power even if you bought a cutting‑edge new computer. In contrast, fitting the UAD1 takes a few minutes, and gives you a huge boost in processing power and a wonderful bundle of high‑quality plug‑ins. Remember though, that like all such DSP designs, you won't be able to run any of your existing VST plug‑ins on it.

If you're in the market for a DSP card, your final choice is likely to be determined by its cost, what additional plug‑ins are available for it, what they sound like, and how much they cost. The Pulsar XTC hasn't got any current support from third‑party developers (although both SPL and John Bowen's Zarg Music do provide a range for the SCOPE and Pulsar models), and while both the Powercore and UAD1 have already attracted support from Antares (makers of Auto‑Tune and Microphone Modeler), no third‑party plug‑ins have yet been released for either product. Mind you, it's apparently fairly easy to port TDM plug‑ins to Powercore, which may boost its roster.

However, as always, your choice should be made on what's available now, and this makes things rather simpler. The Pulsar XTC is cheapest at £799, but only currently runs on the PC platform. It comes with the largest bundle of over 30 plug‑ins, synthesizers, and samplers, which will endear it to many musicians, but its Masterverb isn't in the same league as its competitors' reverb algorithms. The TC Powercore bundle at £999 includes the excellent TC Megaverb, along with the TC Chorus/Delay and EQSat, and for a limited period only, also includes TC's MasterX 3, a three‑band dynamic tool based on the TC Finalizer. However, it currently only has Mac drivers — PC ones are apparently expected by Christmas. The UAD1, by comparison, has the excellent Realverb Pro, 1176AN Limiting Amplifier, Teletronix LA2A Leveling Amplifier, CS1 Channel Strip and its individual components. This is a larger bundle, and at a slightly cheaper price of £880, but this time there are only PC drivers, although once again Mac ones are expected later on this year.

At the moment, therefore, the answer is clear: if you want a high‑quality DSP reverb in your bundle, you only have one choice, depending on your chosen platform. Mac owners will buy the TC Powercore, while PC owners will buy the UAD1. Once PC/Mac drivers are available for all three products I suggest you re‑evaluate and audition, based on what plug‑ins have become available for each one. Personally, I feel that Universal Audio's UAD1 is currently the strongest product, thanks to the strength of its Powered Plug‑in bundle and the amount of processing power it provides.

Universal Audio have asked for the following clarification to be included with this online version of our review. Unfortunately, press deadlines meant that this text could not be included in the printed versions at the time.


In a recent email we claimed that our UAD‑1 card is 2.5 times more powerful than a Digidesign Mix Farm card. We thought it would be a good idea to tell you how we made this comparison as it was based upon the ability of the Mix card to run RealVerb Pro. RealVerb Pro is the only plug‑in that currently can run on both cards. In this case, the comparison resulted in 10 RealVerb Pros on the UAD‑1 and 3 on the Mix Farm. Digidesign notes that the comparison did not take into account that 50% of the Mix Farm card’s processing capacity was unused and that this additional unused processing capability is available for other audio tasks.

We want you to be aware that the above test is based only upon RealVerb Pro, which currently is the only plug‑in that runs on both platforms. Universal Audio recognizes that these types of tests may not be a complete indication of the overall power available on either of these cards.

In this same email we claimed that the current MSRP of the Digidesign Mix Farm is $4K when in fact we have been told the list price is actually $3995 and is most often sold for less.

Additionally we would like to clarify that there was no intended implication that a Digidesign Mix Farm is not capable of running 32 EQs, 16 compressors and 3 reverbs. Digidesign reports that a Mix Farm is capable of running 48 4‑band EQs, 45 compressors and 4 stereo D‑Verbs. We note, however, that this does not provide an "apples‑to‑apples" comparison, since the specific algorithms mentioned in this example are not available on both platforms.

And finally, we want to be clear that at this time Universal Audio has no plans to develop Powered Plug‑Ins for the Digidesign RTAS format.

Test Spec

  • Universal Audio UAD1 version reviewed: 1.1.
  • Pentium II 450MHz PC with 384Mb RAM, running Windows 98SE.
  • Motherboard: QDI Brilliant 1 with Intel 440BX chipset.
  • Tested with Steinberg Cubase VST 5.0 r5, Wavelab 3.04c (build 67).

UAD1 Specifications

  • Hardware format: 7‑inch long PCI 2.1‑compliant card.
  • Audio formats: any supported by host application, including 24‑bit/96kHz.
  • DSP type: not revealed.
  • Internal data format: IEEE 32‑bit floating‑point and double‑precision processing.
  • Internal data bandwidth: 11000Mb/second.
  • On‑board RAM: 4Mb of 1200Mb/second memory.
  • Bundled plug‑ins: Realverb Pro reverb, 1176LN and LA2A vintage compressors, CS1 Channel Strip including EX1 five‑band parametric EQ and compressor, DM1 Delay Modulator, and RS1 Reflection Engine.

System Requirements

The UAD1 will run on any PC running Windows 95 OSR2, 98, 98SE, or ME, with either an AMD Athlon processor, or an Intel Celeron or Pentium (original, Pro, II, III, or IV ranges). You'll need at least 128Mb of RAM, and 30Mb hard disk space. At the moment only one card per computer is supported, but UA are hoping that multiple cards will be supported under Windows 98/ME and Windows 2000 by the time they release their Windows 2000 drivers later on this year. Suitable host applications include Cubase VST 5.0, Logic Audio Platinum 4.7, Nuendo 1.51 or newer, and Wavelab, while Mac support for both VST and MAS formats is expected later on in 2001. UA haven't yet decided whether to implement support for DirectX‑based applications like Sonar.

As for the DSP overhead of the Powered Plug‑ins themselves, a minimal amount of native processing is used for the audio interface. To let you calculate how many of each one the card itself could feasibly run simultaneously, here are my measurements, taken at 44.1kHz sample rate (higher values will increase DSP overhead proportionally):

  • DM1: 3% CPU, 5% RAM.
  • EX1: 4% CPU, 0% RAM.
  • RS1: 5% CPU, 5% RAM.
  • LA2A: 8% CPU, 0% RAM.
  • CS1: 9% CPU, 9% RAM.
  • 1176LN: 13% CPU, 0% RAM.
  • Realverb Pro: 13% CPU, 0% RAM.

Competing Cards

'Next‑generation' DSP cards is a hotly contested field, and a battle is raging based on the comparative performance of the three main contenders from Creamware, TC Works, and Universal Audio. Universal Audio claim that the single chip used by the UAD1 has 10 to 15 times the processing power of other audio DSP chips, including both the Motorola 56K ones used by TC's Powercore and the SHARC chips found in Creamware's Pulsar XTC. In addition, where the UAD1 uses a single non‑partitioned floating‑point chip, which could be used in its entirety by one 'super plug‑in', the other two both use multiple chips, which may limit the ways you can use available DSP power, as well as possibly wasting some. For instance, if you had a plug‑in that took 80 percent of one of the Powercore's four chips, you could only run four of these in total, wasting 20 percent of each chip's DSP.

On a purely practical note, the UAD1 card is considerably smaller than both the Powercore and Pulsar XTC, which will make it easier to fit into some systems. It also has 4Mb of onboard RAM, which makes it easier on the host system when running delay and reverb plug‑ins — otherwise, these have to ferry lots of data back and forth on the PCI buss.


  • Will work with any VST‑compatible host application.
  • Very easy to install, and plug‑ins appear just like VST ones.
  • Bundled plug‑ins are all of excellent quality.
  • Compact card size will suit those with cramped computers.


  • Like all such designs, it only runs dedicated plug‑ins.
  • None of the DSP cards yet has much third‑party support.
  • Mac support for VST and MAS not yet available.
  • 'Async' distortion happens too often with version 1.1 software.


Universal Audio's UAD1 provides an incredibly easy way to adds lots of DSP power to your existing computer, and with sufficient third‑party support is bound to prove very popular.