Digital Drive: REVIEW: Behringer Ultracurve Pro 2496 DAC Processors by MB

Model:	Ultracurve Pro 2496
Category:	DAC Processors
Suggested Retail Price:	$379.99
Description:	24/94 digital EQ, A-D/D-A
Manufacturer URL:	Behringer
Model Picture:	View

Review by MB ( A ) on July 01, 2003 at 18:26:42
IP Address: 165.21.154.11

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Firstly, a big THANKS to Thorsten and others who have provided plenty of background information based on the older Ultracurve 8024. It's cut down my learning curve by weeks. Anyone contemplating purchase must read Thorsten's review and articles on target curves. Articles in the Harmon and Tag Maclaren site have also been tremendously useful.
I became acutely aware of the need to address some room modes when I borrowed a CD (Mozart wind serenade 'Gran Partita', mastered by Tony Faulkner). On my main system, one bass note, played by double bass (or violone, the historical bass?), created a huge, irritating drone in the room. The note was a B-flat, but in an unusual tuning -- slightly flatter than modern concert pitch. Since the piece is in B-flat, the note kept re-occuring, and the CD was un-listenable. On my 2nd (bedroom) system it was clear that the recording was not at fault.
Description of Ultracurve Pro 2496 (DEQ2496 in short): the DEQ2496 is almost like a Swiss-knife digital EQ system -- analog & digital in, graphical, parametric, dynamic EQ, limiter, real-time analyzer, auto-EQ, feedback destroyer (for PA applications), digital & analog out.
My application: ONLY digital in, EQ (graphical and parametric), digital out to dac. In future I may use analog in/out, but for non-critical applications (eg. FM tuner). The A-D and D-A functions are NOT reviewed hear.
Learning curve: as an engineer and amateur musician, it's fairly easy for me to relate frequencies, resonance, modes, etc, so my experience should be taken in this context. I had already noted the occurence of resonant notes on certain CDs, and mapped them out to be 56Hz, 44Hz, 88Hz, and so on. After a few days of basic, trial and error EQ, by ear and using the AutoEQ function, I went for the 'serious' tuning.
Tuning out LF room modes: for this to work at all, you need pretty precise info on speaker / room LF behaviour (see suggested articles). ETF5.x measurement software to the rescue! It provides the LF response and MLS graphs that make it fairly clear where the resonances are. Most of my guesses regarding the frequencies were quite accurate, but the graphs showed much more, and quantified the problems. Each channel was addressed independently. This was done up to 150Hz. Tuning them out using notch filters on the DEQ2496 was pretty easy (4-5 filters per channel, narrow-band, -3 to -9dB).
AutoEQ for mid/high. I took the relatively easy way out for mid/highs, and let the DEQ2496 AutoEQ function look after it. It requires a 'target curve' -- the desired response -- to be keyed in, and them tries to approach that curve until you say, 'enough!'. My curve was had a mild LF rise (2dB), and HF dip to -4dB at 20kHz.
The DEQ2496 in use: much of the above has not talked about performance of the DEQ2496, because in large, it's just doing it's thing -- providing the EQ I ask of it. The digital source is as before (my humble Philips player), and the analog output is coming from my very musical, moderately modded CI-Audio VDA-1. If the DEQ2496 approached forced me to abandon the CI-Audio dac, I probably would have hesitated to go this way.
'Transparency' of the DEQ2496: my only measure is how my dac sounds direct from the transport, and through the DEQ2496 in straight-through (bypass) mode. I can't perceive any difference. Sure, there might be something, but it's small.
'Sound' of the DEQ2496
1) In managing LF room modes: excellent!! The problem CDs (very few to begin with) are sounding great. Others continue to sound as good as ever. Bass quality has changed -- less overhang, fewer obvious boomy notes. I deliberately kept the notch filter settings moderate, and therefore some of the inherent character of the listening room remains. It seems to me that fully neutralizing the modes can make the bass sound too sterile.
2) Mid/HF EQ: very good. Here we're playing with room / speaker interaction, adjusting speaker voicing, etc. Easy to be 'too much of a good thing'. AutoEQ suggested some moderate adjustments. In much of the spectrum it was flat, with some 2-5dB crests and dips. One exception was at 15kHz (+9dB), which I cut to +3dB. The range of target curves is infinite, so there is no set solution. Overall I found the benefit to using AutoEQ in my system to be signigicantly better intelligibilty. Voices and midrange seem more integrated.
This is one $300 investment that's here to stay. It's hard, no IMPOSSIBLE, to imagine another component that has this impact for the money. The Behringer's not the only digital EQ with the functionality and capability I've described, but it certainly does the job very well for me.

Product Weakness: Not a cure-all. Room treatment, component matching, all the usual factors still hold, perhaps even more so. Learning curve, patience in tuning. Measured mic required. Builtin AutoEQ will not address LF room modes. Possible to get to digital clipping unless overall gain is carefully tuned down.
Product Strengths: Addresses otherwise hard-to-fix room issues, esp. LF problems. Transparent digital pass-thru (in-> EQ-> out). Flexible parametric EQ settings.

Associated Equipment for this Review:
Amplifier:	AKSA, Rotel bi-amp
Preamplifier (or None if Integrated):	Own battery-powered buffered attenuator
Sources (CDP/Turntable):	Philips (as transport), CI-Audio VDA-1 dac
Speakers:	Gradient Revolution
Cables/Interconnects:	DH-Lab, own DIY based on Klotz cable
Music Used (Genre/Selections):	Classical, acoustic
Room Size (LxWxH):	30 x 17 x 10
Room Comments/Treatments:	Some diffusers
Time Period/Length of Audition:	1 week
Type of Audition/Review:	Product Owner

Product Weakness:	Not a cure-all. Room treatment, component matching, all the usual factors still hold, perhaps even more so. Learning curve, patience in tuning. Measured mic required. Builtin AutoEQ will not address LF room modes. Possible to get to digital clipping unless overall gain is carefully tuned down.
Product Strengths:	Addresses otherwise hard-to-fix room issues, esp. LF problems. Transparent digital pass-thru (in-> EQ-> out). Flexible parametric EQ settings.