Take Behringer's best-selling product and add a sprinkling of input from the Midas design team. Is this a recipe for sonic success?
Behringer's Ultragain ADA 8000 — a simple ADAT interface with mic and line inputs and analogue line outputs, which we reviewed in SOS June 2004 — has been one of the company's most popular and best-selling products, typically being used to expand the analogue I/O of USB or Firewire computer interfaces via their spare ADAT ports. Its technical specifications were, shall we say, less than whelming: it was never going to set the world alight from a quality point of view, but many users appreciated its usefulness and cost-effectiveness nonetheless. A decade later, and both technology and users' quality expectations have climbed, even for budget gear — so Behringer decided to revise this old favourite.
The new ADA 8200 is identical in all practical respects to the ADA 8000, except that it now features higher quality converters and new mic preamps, courtesy of the Midas designers (Behringer's parent company having acquired Midas and Klark Teknik a few years ago). Comparing the original and new models side by side, the only visible differences are a stylish satin-red front panel on the new version, and slightly different gain knobs with much narrower fluting. The gain-knob detents have gone, too, but in essence all the controls and connectors are identical, front and back. Digital interfacing is still via ADAT lightpipe ports, with electronically balanced analogue outputs via XLRs at the back, and both mic and line inputs connected on the front.
All the important changes, therefore, must be on the inside, and one of the most significant is that the linear power supply of the old model, which used to run very hot and was a common point of failure, has been replaced with a universal switched-mode power-supply module. This accepts any mains supply between 100 and 240VAC, and it runs considerably cooler than the old design. A bonus benefit is that the power consumption has been reduced from 25W to 15W, and the absence of a toroidal mains transformer also makes the unit lighter and better balanced.
As before, phantom power is switched globally with a push-button on the right-hand side of the front panel, and this illuminates green when disabled and red when active. On the review model, the phantom-power voltage measured fractionally low, at 46.5V, but that's still within tolerance and it didn't drop significantly when all eight channels were supplying power to microphones.
Clock-master (yellow) and clock-lock (green) LEDs positioned just above the phantom button indicate the unit's clocking configuration and status, as before, which is determined by a rear-panel slide switch. The master internal clock sample-rate options are still restricted to just 44.1 and 48kHz (no double or quad rates have been added, I'm afraid), and the same slave-clock options have been retained from the ADAT input or an external word-clock connected via a BNC socket.
Each of the eight input channels is equipped with an XLR and a quarter-inch TRS socket, receiving electronically balanced mic- and line-level inputs, respectively. (Phantom power only appears on the XLR, of course.) Both input formats are actually active and summed together all the time; the line input is simply padded down and mixed with the mic input before being fed into the mic preamp. The revised mic-preamp circuitry is rumoured to be similar to that of the Midas Venice, although I couldn't authenticate that. Strangely, though, given that this is supposed to be a brand-new design, the mic- and line-input impedances both measured exactly the same as on the old model. My NTI Minirator Pro indicated a 2kΩ impedance for the mic inputs and 18kΩ for the line inputs, whereas the manual suggests that they should be 2.7 and 20 kΩ, respectively, for the ADA 8200.
Signal-level indication for each channel is via two LEDs located above each input XLR: 'Signal' (green) illuminates when the output exceeds -40dBFS, and 'Clip' (red) lights when the output reaches -3dBFS... so you really won't want to be seeing any red lights, ever!
A rotary gain control, without detents, has no panel markings at all on the new model. The manual claims that the nominal ranges are +15 to +60 dB for the mic inputs, and -5 to +40 dB for line inputs. In fact, my Audio Precision bench tests showed the actual ranges to be +3 to +56dB and -16 to +36dB, respectively — so around 53dB overall range.
Of course, the important practical issues are what the workable minimum and maximum signal levels really are. The absolute maximum signal level (producing 0dBFS at the ADAT output) tolerated at the line input is about +31dBu, while the maximum via the mic input is +12dBu — which is a few decibels more headroom than on the ADA 8000. So you'd have to try quite hard to overload the mic preamp in normal project-studio situations (you'd need a mic with a 16mV/Pa sensitivity right next to a source producing 140dB SPL, for example!).
For the minimum acceptable levels, I generally aim to get an average signal around -15dBFS when tracking, and the ADA 8200 can do that if the mic input is at least -56dBu (-37dBu on the line input). To put that into context, a typical dynamic mic with a sensitivity of 2mV/Pa will produce -56dBu when exposed to a source producing 90dB SPL, as will a capacitor mic with a sensitivity of 16mV/pa in front of a source generating 78dB SPL. So, for example, there should be no problem accommodating a Shure SM57 close to a guitar amp, or an AKG C414 for a spoken word session, respectively.
Electronically balanced analogue line outputs are provided via XLRs on the rear panel, with a full-level 0dBFS ADAT input providing +16dBu at the corresponding analogue output. This is lower than the norm: a reference -18dBFS signal level would produce -2dBu at the analogue output, for example, between 2 and 6 dB lower than most professional converters. If you were using the ADA 8200 to interface line-level outboard equipment with nominal +0dBu analogue input and output levels, the channel gain controls would need to be set around 11 o'clock for unity gain through the unit, and the digital I/O level would be around -16dBFS.
Working through a variety of AP bench tests, the new 8200 Ultragain demonstrated generally improved specifications compared with the outgoing model, although not dramatically so. Testing analogue line-in to line-out (+4dBu signal, unity gain, ADAT ports linked), the THD+N measured -96dB (0.0015%), which is a good 3dB better than the previous incarnation. Harmonic distortion is also usefully lower across the entire bandwidth in the new model, and especially across the high end. The noise floor sits at about -83dBu, giving a total dynamic-range capability of 98dB, and the microphone input EIN figure is -129dB, again roughly 3dB better than the old 8000 model. On a practical level, it's good to see that the gain-versus-rotation of the input gain control is a little more linear across the whole control range, with less 'bunching'.
The ADA 8200 employs different converters, the new devices being made by Cirrus, and the latency through the unit is substantially lower, measuring just 0.55ms at a 44.1kHz sample rate (compared with 1.46ms for the old ADA 8000). Further improvements can be seen in the frequency response, too: although the low-end has an identical roll-off (-3dB at 6Hz) to the outgoing model, the high-end shows far less in the way of amplitude ripples around the cutoff frequency. The minor drawback is a slight HF droop (-1dB at 20kHz), but this translates into a smoother and more classy-sounding overall tonality. It appears that minimum-phase filters are being employed here, too, rather than the linear-phase filters of the previous design: the impulse-response plot certainly appears to show an absence of pre-ringing, anyway.
A reasonably useful indication of converter quality is the AES17 dynamic-range figure, and in the case of the ADA 8200 my tests obtained values of 103dB (A-wtd) for the A-D stage, and 104.5dB (A-wtd) for the D-A stage. To be blunt, both are quite disappointing figures, since most modern mid-range interfaces achieve around 110-115dB, and the best high-end converters are delivering figures in the low- to mid-120s. Having said that, the combined A-D and D-A chip used here is only specified with a dynamic range of 105dB — so Behringer's engineers have clearly extracted the best possible performance from it.
The marketing tag-line for the ADA 8200 should be something like 'the king is dead; long live the king!' because the new model is, in every practical way, exactly the same as the old. It has the same I/O, the same controls, the same operation, and the same restrictions. Yes, there are welcome improvements in the tech specs, but they really are only small improvements. On a more practical level, the muting and ADAT sync issues associated with the later batches of the original ADA 8000 have been addressed, and there is better gain-knob precision and linearity, in part because the frustrating detents of the original model have been removed. In use, the converters sound noticeably sweeter and cleaner, and the mic preamp is also a little quieter and more neutral, but nothing here is setting any benchmarks.
The bottom line is that the ADA 8200 is a convenient, low-budget, workaday ADAT interface and eight-channel preamp. It's nothing special, but it is very handy and very cost-effective — and there's nothing wrong with that. It's also usefully and noticeably better than the original version. That's probably going to ensure that the ADA 8200 will take the honour of becoming Behringer's best-selling product.
The ART TubeOpto8 is probably the closest match to the Behringer ADA 8200, with conversion to and from ADAT at base sample rates. It features eight valve mic preamps (two with instrument inputs) plus high-pass filter, phase and pad switches on every channel. Focusrite's OctoPre MKii provides eight good mic preamps, two with instrument inputs, A-D conversion to ADAT (with 96kHz capability) and analogue outputs, but no D-A facilities. The Presonus DigiMAX D8 offers much the same input and output features as the Focusrite, but only for standard sample rates.
A comparison of the residual distortion levels of the old ADA 8000 (blue) and new ADA 8200 (green). The new model is clearly much better and more consistent, especially above 1kHz.
An FFT spectrum plot of the noise floor of the ADA 8200 in the presence of a 1kHz, +4dBu line-level input. The spikes to the left are power-supply residuals (all close to or below -100dBu), while those to the right reveals some harmonic distortion (again typically around -100dBu). Compare this with...
As above, but with the equivalent plot from the previous ADA 8000 model (purple trace). This reveals significant anharmonic distortion products around the +4dBu input signal at 1kHz, with most components only -80 to -90dBu. Clearly, these anharmonic components shouldn't be there, and reveal a poor converter or very poor converter clocking. They would contribute to the impression of harshness, too. Fortunately, the new 8200 model has overcome this problem completely.
The frequency responses of the old ADA 8000 (purple) and new ADA 8200 (green). Note the very expanded gain scale. The old model exhibited significant response ripples and a slight gain rise leading up to the cutoff frequency. By contrast, the Cirrus converters employed in the new 8200 exhibit a gentle roll-off and no ripples. Both products have similar LF roll-offs reaching -3dB at 6Hz.
The impulse responses of the new (green) ADA 8200 and old (purple) ADA 8000. The previous version shows a typical symmetrical impulse response, indicating a linear-phase filter with classic pre-ringing. In contrast, the new model's impulse response shows no pre-ringing at all, so must have a minimum-phase filter. The latency through the converter is also considerably shorter (0.55ms versus 1.46ms at a 44.1kHz sample rate).
The original ADA 8000 used Wavefront AL 1201G D-A and AL 1101 A-D converters, with TLO74 op-amps for all the buffer amp stages, and Wavefront AL 1402/1401 ADAT interface chips. Unfortunately, some later batches of the last of these were known to suffer compatibility problems (mainly unreliable synchronisation) with MOTU interfaces — and Behringer's product web page has a specific disclaimer about using the ADA 8000 with MOTU interfaces. The converter chips used in some later ADA 8000s were also known to suffer from unwanted muting with low-level input signals.
Happily, all of these issues have been addressed in the ADA 8200's redesign. A new combined A-D/D-A converter chip (the Cirrus CS4270) is employed with NJM4580 op-amps for the buffer stages. I found no evidence of any low-level muting! The review ADA 8200 model featured some of the first batch of Behringer's own custom-designed ADAT interface chips (marked CS7242/7241), which are claimed to overcome the previous Wavefront compatibility problems. Behringer's bespoke ADAT interface chips apparently employ a different internal clocking arrangement from that of the Wavefront design, and it is claimed to avoid the Wavefront's instability issues. Unfortunately, I was unable to test this aspect myself, as I couldn't gain access to a MOTU interface in time, but it did work reliably with several RME interfaces.
It's worth noting that Behringer are developing in-house IC design as an important core competency for the company, because moving more and more towards integrated solutions provides very obvious benefits to a company that is seeking to produce high-quality, low-cost products. Of specific interest, I'm told that work is quite advanced on a new 'cutting-edge' Midas preamp IC, offering 0.5dB gain steps with zipper noise-free gain adjustment, and extremely low noise and THD figures.