Denon AVR-5805 AV Surround Receiver
By Thomas J. Norton   •   January, 2006 Denon's flagship AV receivers have long been rated among the best, if not the best that money can buy. They've also been loaded with features, sometimes to the point where using them for anything but normal operations is a real challenge for the average user. The company's latest top-of-the-heap effort, the $6000 AVR-5805, is both of these things, and much more.

The feature set of the Denon is so rich, in fact, and its operation so flexible (or complicated, depending on your point of view), that it takes a 191 page manual—all in English—to explain it all!

The Cook's Tour
If the 5805 is complex—and it is—it is also designed with the custom installer in mind. That means that most buyers will not be bringing it home and setting it up themselves. They won't have to deal with its near 100 lb weight (there's a fifth foot at the bottom center of the chassis to support the unit's massive toroidal power transformer), and many of them will be using one of those slick but expensive aftermarket touch-screen remotes, which will make access to the receiver's features much more straightforward.

And this receiver is truly loaded with every bell and whistle you could wish for—and more than a few you wouldn't have even thought of. It carries the latest THX Ultra2 certification. In addition to two new surround modes, THX Ultra2 Cinema and THX Music (both designed for 7.1-channel setups), all of the usual suspects are in there: Dolby Digital, Dolby Pro Logic II and IIx, DTS (ES matrix and discrete, Neo:6 Music and Movie, and DTS 96/24), and a bushel of those aptly-named DSP surround modes like Jazz Club, Stadium, and Church. HDCD decoding is also included.

There are also 10 discrete channels of amplification. These may be configured to operate in a number of ways. For example, you can set up a 5.1-channel system in the main room and use those additional amplifiers to drive another 5.1-channel system in a second room. Or you could set up a 7.1-channel system in the main room with side and back surrounds and the front speakers bi-amped.

Each of the 10 channels is rated at 170Wpc into 8 ohms, though the specification is not for all channels driven at once. In fact, if you read the spec carefully, it only applies to a maximum of any two channels driven simultaneously. (We were able to measure the amp with seven channels driven; our test load does not go up to 10 channels. See "Measurements.") Most of my listening, however, was done in 5.1-channel mode, which left the extra five channels with little to do but heat up the receiver (it runs very warm, and even with only five channels operating draws over 200W when on and idling).

The 5805 also includes Denon's Dual Surround Speaker Mode, allowing the user to set up two different sets of surrounds and select them separately from the receiver depending on the program requirements—for example, side-mounted dipoles for movies and rear-positioned, conventional forward-radiating designs (perhaps identical to the fronts) for music.

Internally, the receiver employs independent power supplies for each critical subsystem. There are a total of six power transformers, including that large main toroid. The latter also has dedicated sub-windings. The power supplies total 132,000 microfarads of total storage capacity. Low- and high-level audio and video circuits are kept separate to minimize interference.

Denon's DDSC-Digital (Dynamic Discrete Surround Circuit) makes use of three 32-bit, floating point DSPs for the main zone and a 32-bit floating point SHARC DSP for Zone 2. The 5805's Advanced AL24 DSP audio processing employs eight digital-to-analog converters, two per channel in differential configuration, all of them 24-bit/192kHz. The receiver's analog-to-digital conversion is also 24-bit/192kHz.

The receiver is also equipped with Denon's proprietary Denon Link and two IEEE 1394 connections. Either type of connection allows a direct digital input of multichannel sources from universal disc players that have one or both of these interfaces.

Inputs to Go
The AVR-5805 is equipped with more audio and video inputs, both analog and digital, than anyone is likely to use up (see "Specifications"). Its component and digital video inputs—yes, there is HDMI (and limited DVI) switching—are rated for a bandwidth of 100MHz—more than enough for HD. Furthermore, there is video up and down cross-conversion between composite, S-Video, and component video.

The receiver is also equipped with a Faroudja DCDi processor for deinterlacing 480i video sources to 480p progressive. According to the manual, non copy-protected material can also be upconverted to 720p and 1080i. In practice, I found that most of the commercial DVDs I tried could be upconverted to those higher resolutions with no problem.

Neither cross-conversion of video sources nor deinterlacing and scaling is available with DVI or HDMI inputs. These digital video inputs limited to video switching only, with no other processing of any kind. Nor do they offer on-screen menus, which are available at all analog video outputs, including component.

Denon plan to announce an upgrade providing HDMI scaling, and conversion of analog video inputs to HDMI (but not downconversion from HDMI to analog—why would you want to do that anyway?) at this weeks Las Vegas CES. It will be available in March. While it will be incorporated into new units shipping after that date, older AVR-5805s can be retrofitted with it, as well.

If you've checked the specifications already, you'll note that there are two multichannel analog inputs, one 5.1-channel, and the other 9.1. The latter is provided for future surround sources that may require it (there are, of course, no current sources with this many discrete channels).

While there are main zone preamp outputs for up to 9.1 channels, it is also possible to configure the main zone for up to 9.3 channel operation with three subwoofers—stereo or front/rear plus a separate subwoofer for LFE. In such a 9.3 setup, two of the pre outs for zone 2 (center and subwoofer) are diverted to main system use for driving the additional subs.