Music in the Round #65

After going so far off the beaten path in my last column, with examinations of digital signal processing (DSP) from miniDSP and Illusonic and multichannel in-room measurements, this month I take a look at and listen to a new preamplifier-processor from Yamaha, along with its companion multichannel power amplifier. The Japanese company (footnote 1) was a pioneer in digital signal processing (DSP) and multichannel sound, but for a long while now has been swimming in the mainstream of audio/video receivers and home theater.

Yamaha Aventage CX-A5000 preamplifier-processor
When I saw the first notices of the Aventage CX-A5000 11.2-channel pre-pro, I was first struck by its price of $2999.95, which seemed to indicate that Yamaha was making a bold bid for leadership in the under-$5000 category. Further examination revealed that the CX-A5000 retains all the home-theater features of their audio/video receiver line—including 11.2 channels, 33 CinemaDSP modes, and video processing—which interest most serious music listeners very little. However, I was attracted by the 11 channels of balanced outputs, dual audio configurations, the ability to stream 24-bit/192kHz FLAC and WAV files, ESS Technology Sabre32 Ultra DACs for all channels, and Yamaha's YPAO room-optimization software with multi-point/speaker-angle measurement. Overall, the CX-A5000 did not look like a mere repackaging of half an AVR.

Except for the Krell 707, the Aventage CX-A5000 is the biggest pre-pro I have ever hoisted onto my rack. At 17 1/8" (440mm) W by 7½" (190mm) H by 17 5/8" (450mm) D and 30 lbs (13.6kg), it's similar in dimensions and weight to the Marantz AV8801, but more than 2" deeper. Though this may limit the numbers of racks it can be placed in, it turned out that the CX-A5000 ran much cooler than the Marantz, and connecting the Yamaha to my system was not as taxing—its large rear panel is clearly laid out and less congested than those of many of its recent competitors. Perhaps the Yamaha has fewer connectors, but I found everything I needed, as well as an array of legacy connections.

I connected a cable box and disc players via the CX-A5000's HDMI, S/PDIF, and multichannel analog RCA inputs, one of the HDMI outputs to my plasma display, and five channels' worth of XLR outputs to my Bryston 9B-STT multichannel power amplifier. The only thing I that seemed missing was XLR outputs for the two subwoofer channels, but since both of my subs accept RCA inputs only, that didn't affect me. Interestingly, the two subwoofer outputs can be designated "Left+Right," "Front+Rear," or "Monauralx2." I chose "Front+Rear," as that's where my subs are. Surprisingly, only the front sub was used with two-channel sources, though both came alive for multichannel. Everything is clearly labeled; if you follow Yamaha's default input designations, little renaming of inputs and outputs will be necessary.

What stopped me in my tracks was the CX-A5000's setup programming and configuration. I like to think of myself as a pro who can investigate a product's menus on my own and figure it all out—especially when, as in this case, the user's manual is provided only on CD-ROM. Manuals are for wimps, right? Generally, I think so, but the CX-A5000's remote control has no button labeled Setup, and its Program and Option buttons didn't get me there. Even the brief, printed Setup Guide was no help—it doesn't tell you how to get to the functions it suggests, and it lacks a map of the remote's buttons. It turns out that the gateway to controlling the CX-A5000 is the remote's On Screen button, even though, in my experience, that designation suggests access to program info. Once I found the way in, Yamaha's graphic user interface was pretty to look at and easy to use, with decent explanations of each option. But Yamaha—if you're not going to provide a printed manual, please make the Setup Guide a bit more informative.

And while I'm carping, how about that remote? It has an amazing array of abilities, some hidden under the lower third of the panel, which folds down for access. I found it so powerful that I never had to use the CX-A5000's front panel, except to plug in the calibration microphone or a USB device. The only problem is that the remote's on-button labels are unreadable unless one squints and turns on the backlighting, even with normal daytime illumination. Eventually, I memorized the positions of the buttons I most frequently used, but using others remains an annoyance. Let's be grateful that Yamaha's iOS control app fills the bill. Rant mode off.

Like other modern pre-pros (except for some of the high-end ones), the Yamaha CX-A5000 will decode and properly handle any format and codec you can throw at it. Selecting the Straight mode bypasses DSP and bass management for all of these, including DSD. Analog inputs can be redigitized for DSP and bass management—or, by selecting Pure Direct, passed to the analog outputs without conversion.

For a week or so, I listened to/through the CX-A5000 as delivered, having manually input only the channel-level and speaker-distance settings, based on my experience with other pre-pros. The sound was remarkably clean and open, and conveyed a refreshing sense of transparency with high-quality recordings. Digital-to-analog conversion is handled by ESS Technology's ES9016 Sabre32 Ultra DACs, which are second (but close in specs) to the widely praised ES9018 chips. I can't simply infer that the CX-A5000's vivacious sound was a direct result of these DACs, but I suspect that they were major contributors. Indeed, it was only my curiosity (perversity?) that compelled me to undertake a full setup, such was the innate clarity and powerful dynamic capabilities of direct playback, digital or analog, via the CX-A5000.

After my years of fooling around with other room-correction and setup programs, the Yamaha Parametric Room Acoustic Optimizer (YPAO) and Reflected Sound Control (R.S.C.) were terra incognita. The CX-A5000 offers seven parametric YPAO filters for each main channel and four for each subwoofer channel. The setting ranges for the filters are –20 to +6dB for gain, 31.3Hz–16kHz for center frequency (31.2–250Hz for subwoofers), and 0.5–10.080 for Q. After executing the automatic procedure, the user can choose from among four options: YPAO-Flat, YPAO-Front (equalizes all speakers to match the three front speakers, which remain uncorrected), YPAO-Natural (inserts a gentle high-frequency rolloff of about 6dB from the midrange up to 16kHz), and Through (bypasses all EQ). In addition, any of the correction sets can be copied into a user-editable Manual option. Finally, the CX-A5000 will store two patterns, including all the correction options for different room conditions or speaker configurations; eg, one listener vs a group, drapes open vs closed, etc. Pretty comprehensive.

I mounted the Yamaha's calibration microphone on a tripod (footnote 2), placed it at the main listening position, and let 'er rip. After YPAO had passed tones through each of the speakers and subs, it prompted me to reposition the mike. I used the same eight mike positions that I've long used. As often happens with auto-EQ softwares, YPAO set the front three speakers to Full Range. I reset them to have a bass cutoff of 40Hz. YPAO did give the smaller surround speakers an 80Hz cutoff, and absolutely nailed all the distances and channel levels. Listening to YPAO-Flat, I felt that the treble was a bit too bright, but YPAO-Natural was just lovely. Midbass with either was smooth, but more prominent than the low bass. While the mids and highs were notably smooth and transparent with YPAO, the bass seemed unimproved.

A look at the graphic presentation of YPAO's correction results revealed all (fig.1). All of the correction filters were of low Q (ie, broad in frequency), and there was little correction in the low end. One of the L/C/R channels now had a filter at 63.1Hz, but the rest were at 78.7Hz or above. No filters below 125Hz were applied to the L/R surround channels, even though their placements in the room's corners subject them to a severe diagonal room mode near 45Hz. Nor were any filters applied to the subwoofers below 125Hz; with the Yamaha's bass management applied at 40Hz (fronts) and 80Hz (surrounds), this meant that YPAO was not applying EQ below 100Hz.

314mitr.Roundfig1.jpg

Fig.1 The results of Yamaha's YPAO room-optimization software for two selected channels.

Even knowing that, and despite its lack of effect on the lows, I continued to prefer YPAO-Natural to Through (no EQ at all), for the former's natural-sounding mids and highs. YPAO has filters that can have their center frequency set as low as 31.3Hz, and a more-than-adequate range of gain and Q, so it could be used for the bass—but it seems that the correction algorithm made no use of these filters. This left me with three options: 1) I could use the RoomEQ Wizard, Omnimic, or XTZPro room-optimization software to measure and develop bass filters to add to YPAO's results; 2) I could add an external subwoofer equalizer; or 3) I could accept the Yamaha's settings and say that, although the Aventage CX-A5000 is an excellent, transparent, capable pre-pro, in this aspect it is flawed.



Footnote 1: Yamaha Corporation of America, 6600 Orangethorpe Avenue, Buena Park, CA 90620. Tel: (714) 522-9105. Web: usa.yamaha.com/AV.

Footnote 2: Yamaha includes with the CX-A5000 a three-spoke platform to be mounted on your tripod, and on which you place the provided mike in each of three locations, for Reflected Sound Control. This allows YPAO to resolve speaker angles and reflected sound, which Yamaha says will provide DSP Effect Normalization when using CinemaDSP functions. Since I have a 5.2-channel system with all the front channels in the same horizontal plane, I only fiddled with CinemaDSP, figuring that it would not be effective. I was right. Had I had any height channels, I suspect this function might have been useful.

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COMMENTS
blackwash's picture

A few years back I owned a Yamaha A3000. YPAO seemed to make little difference where it counted so I measured it. Like Kal, I found some broad EQ, but nothing for the bass either in the main channels or the sub channel.

Pioneer also don't EQ the bass in their receivers.

It flabbergasted me then and still does now. Bass EQ is the one area where you can get a real difference and improvement.

So Kal, did you ask Yamaha why they have made this odd decision?

I like that they have manual EQ (albeit only to 31Hz), but so does the Emotiva UMC200 for 2.5K less.

Then of course, you have Audyssey, which EQs the bass well but insists on doing weird things to the mids and treble as well.

Mystifying.

I'm using Anthem's ARC almost by default as it seems to be the only automatic EQ system that works reasonably well on the bass and can be told to leave the rest alone.

Kal Rubinson's picture

I did not ask this specific question but the lower the frequency, the more DSP work is required.  I take this to underlie many decisions about how to allocate filters in an auto-correction system.  Even Audyssey came around to re-assigning the correction efforts from the rest of the spectrum to the bass in the current XT32 implementations.

One can make a good argument that, in a decent system/room, the best approach, as you point out is possible with ARC, might be to focus all the automatic DSP/PEQ filters on the bass and deal with the range above Schoeder's critical frequency, with in-room absorption/diffusion and/or broad-band tilt control (a la Quad).

tonj's picture

The Yamaha RX-A2030 and above does EQ the sub.

The new 2014 Pioneer models do with new MCACC called Advanced MCACC with Sub EQ.

Kal Rubinson's picture

Yes, YPAO is supposed to do LF/Sub EQ but, in my experience with the CX-A5000, it failed to apply any useful filters to that range.  One could apply them manually with the appropriate measurement tools.

sddawson's picture

I've just installed a CX-A5000, and found your review very useful - thank you. I do have one question - does straight mode really disable bass management? If so, what happens to the bass? Like you, I have mains set up as small speakers, 40Hz crossover. If bass management is disabled, what goes to the sub exactly - all frequencies? The sub light comes on when straight mode is enabled. I actually suspect bass management is still performed. Interested in your thoughts.

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