Denon AVR-2105 7.1 AV Receiver.

Manufacturer: Denon Electronics (USA), LLC, 19C Chapin Road, Suite 205, Pine Brook, NJ 07058-9385; www.usa.denon.com

Price: $649

Source: Manufacturer loan

Major Specifications:

* 90 watts per channel FTC (8 ohms, 20 Hz-20 kHz, <.08%THD)

* 125 watts per channel FTC (6 ohms, 1 kHz, <.7%THD)

* 7.1 channel Auto-Setup function with included microphone

* 3 Assignable component video inputs

* 5 sets composite and "S" video inputs. automatically (with manual override) selects S video

* 2 sets composite and "S" video outputs

* 5 assignable digital inputs (4 Optical, 1 Coaxial) automatic selection over analog input with manual override

* 1 Optical digital output

* 9 analog inputs including analog inputs for multi-channel formats (such as DVD-Audio/SACD)

* 3 analog monitor outputs

* 7.1 pre-amp audio output

* 2 Source, 2 Zone functionality Power Amplifier Assign function, lets you assign 2 of the 7 amp channels to drive second zone speakers directly

* Video Conversion of Composite to S-Video and/or to Component, with on-screen display

* Dimensions: 17.1"w x 6.7"h x 16.4"d

* Weight: 27 pounds

To make room for this review in this issue (I was way late getting it to the editor), I am delaying my in-depth technical analysis until the next issue. Above I list the features of this midpriced AV receiver. More information is available on the Denon website, so for right now, let me highlight a few of the features below:

The Denon up- and down-converts composite video, S video, and component video. With a monitor equipped with only a component input, the S video is down-sampled to component. It does not down-sample composite. If you use S video to connect to your TV, you can also view up-sampled composite video, but again, component is not downsampled component video. If you are using component video to your TV, then both composite and component formats are up-sampled. This is an extremely important feature especially if you are using a DTV or HDTV monitor. Remember your VCR, camcorder, and perhaps other units that source video will not have a component out and they may even not have S video.

The unit has a video display generator that guides the user during system setup and parameter adjustment.

The unit has a phono preamp. The phono preamp design is consistent with other modern integrated receivers. More details in the next issue.

The receiver will lock to 96 kHz data present on an optical input. I did see the receiver do this with a rare DVD, from a small audiophile label that had a flag set to allow 96 kHz data down to the receiver. This could actually sound better!

The unit has preamp outputs, which can be very valuable as will be outlined in my upcoming article on AV receiver basics.

The unit has a second zone function that can also be used to drive the tape monitor outputs, which gives you the flexibility to tape one thing while watching another.

Automatic speaker setup is the distinctive feature of the Denon AVR-2105. A microphone, to be held by a camera stand at the listening position, looks out on an unobstructed acoustic space between it and the speakers. The unit first checks for speaker polarity. This is most important, because it is easy to mess up polarity when moving from two to seven channels and it is hard to identify polarity mistakes by ear. Next, the unit sets distance, eliminating measurements and then dialing them into the receiver; however, your universal DVD player still needs its distance settings. Third, the unit automatically calibrates volume. Checked with a level meter, I found the feature worked well with matched speakers, but was challenged by mixed pairs of different brands with varying spectral profiles (e.g., a speaker with a midrange depression coupled with one whose tweeter level lies slightly about midrange). After the unit completes its calibration, the settings are displayed on the TV screen so you can check them before storing them. The unit sometimes concluded a subwoofer was in the system even when none was present. Manual overrides on other setup screens let you change this any other adjustment that was automatically set. Even without a TV, I was able to run the auto setup and make corrections without much difficulty.

Setup options that are not set automatically include the ability to a) adjust crossover frequency to the subwoofer b) select whether the subwoofer gets LFE alone or both LFE and the main signals, and c) assign optical and video ports. In setup, noise test tones are provided to verify speaker position (the microphone, being omni-directional, cannot do this).

The synthesis modes on the remote are highly useable. One button push selects Neo 6 or Dolby PL II music, and a separate button controls video modes. Accordingly, you can access the music modes without first scanning through the three video synthesis modes. Manufacturer-proprietary DSP synthesis modes (the ones that change frequency response at the rear, add reverb etc. that HF likes but I do not) are selected independently with a third button. You have to click three setup buttons to get to the surround parameters panel (we are talking panel because of the on-screen display, although you can adjust things with the TV off). Although the panel is called the surround parameter (surround width, dimension, etc.), tone control settings among other things are displayed. Parameter adjustments are active for a scant 10 seconds--yuck.

The unit looks upmarket with its high-quality knobs and large fluorescent display. A large knob selects each input in turn as it is rotated, thereby replacing individual buttons for each input. Unfortunately, the knob is not marked, so the sequence for nine inputs needs to be memorized. Proving inconvenient, the rotary control does not select the multichannel analog input for DVD-A/ SACD--that's accomplished with a front-channel button. On the remote, inputs are selected with well-organized buttons.

The universal remote supports eight external devices that are selected by sliding switches; therefore, the mode activated by the remote is a constant that cannot be accidentally changed by an errant button push. Buttons are varied in shape and multi-colored. For the most part, good contrast provides for readable lettering, even though the type is small. Front panel controls have little similarities with the remote. Nowhere on the front panel is there an entry point for synthesis adjustments or system setup. The upshot: don't lose the remote.

Direct and normal modes are offered in stereo. The instruction manual glosses over the differences, but I assume direct defeats the tone controls and analog bass management. The analog signal path is made up of a series of small-scale integrated (SSI) circuits. This approach ensures a high dynamic range by allowing for the use of high-performance SSI operational amplifiers that operate on full +15 volt supply rails. Solid state analog switches are implemented with CMOS transistors. These switches are used in all AV receivers to route all the I/Os through the receiver as well as take signals to the ADC and take signals from the DACs. CMOS transistors operating as analog switches are also more linear when powered by [+ or -]15V rails. The more I thought about this, the more impressed I became. The approach is complex, but it allows the analog section to have distortion and dynamic range performance rivaling high-end stereo preamps, which are often made from the same SSI ICs. More information on the internals of the Denon in the next issue.

An analog highpass filter is an option in the direct mode, allowing a subwoofer to be used in stereo mode without having to do an ADC operation on the analog input that will be directed to the satellite speakers.

The DAC's typical distortion is equivalent to 15 bits and no worst-case specification is given. A worst-case noise + distortion (SNRD) with the input reduced to -60dB output is 17-bit equivalent with a bit added at typical levels (these are A-weighted specs). The passband ripple of the digital filter is [+ or -]0.06 dB and the stop-band attenuation is 52 dB, reflecting a short tap length.

The ADC has similar spec. It will digest analog signal sources (tuner, analog tape, phono) without degradation provided the incoming full-scale signal level is within a sensible range. Unlike A DVD-RW or mini-disc recorder, there is no analog gain adjustment before the ADC and no level meter to help adjust the gain.

The main transformer has five secondary windings. A small additional transformer keeps electronics active that can respond to the remote. The primary rectifier for the power amp is a 12,000 [micro]Fd 63 working volt unit that does not store enough charge to allow seven channels of amplification to keep the power rails at a steady value when driving full power into low impedance loads at low frequencies Complete info on the power supply must wait until the next issue.

Denon manages to get good performance from its minimalist power amplifier (circuit details next issue) with a low rated 0.08% distortion (20 Hz-20 kHz) under FTC test conditions. Into 8 ohms, it swings 38 volts based on the power specs provided by Denon. From the spec sheet, it can be inferred for power into a 6 ohm load that amplifier is already current-limited: it swings 32 V at 1 kHz, 6 ohms, 0.7% distortion. The 6-ohm spec is for continuous power. Although the spec is unclear, I believe the unit passes the FTC pre-conditioning test at 6 ohms. Many AV receivers do not. From the specs, the unit sources slightly less than 5 amps into 8 ohms and a little over 5 into 6 ohms under steady-state conditions.

Sanken power Darlington 2sd2390/ 2sb1560 complementary pairs are used as the output devices. The specs for these transistor indicate a maximum dynamic (100msec isolated burst of 1kHz sine waves) current of about 15 amps could be achieved within the safe operating area of the transistor but I have no test equipment to determine whether the Denon does this in real life and Denon cannot supply dynamic specifications for units sold in the US (FTC rules to prevent abuse of this spec). From the unit's design, including its advanced power amplifier protection circuitry (no obsolete analog current limiters), I believe the unit will have no trouble driving low-impedance loads, including reactive loads. I never felt I was power-limited by this receiver using any speakers on hand, even in very big rooms.

Automatic speaker setup and the extremely high quality of the low-level analog signal paths are the most attractive aspects of the audio sections of the Denon AVR-2105. The man/machine interface is excellent from the remote, but needs improvement from the front panel. The DAC performance was a little less stellar. I cannot say what the competition offers at this price range; you may need to spend $1000+ to find a DAC with 18-bit worst-case performance in an AV receiver. I remain on the outlook for a lower-cost alternative. On the positive side, the unit has a high-class look and feel and its internal construction is solid. With the variety of inputs and outputs supported by the unit, the Denon AVR 2105 gets my seal of approval.

For $50 more, consider upgrading to the new AVR 2106, with user-adjustable seven channels of digital equalization, its automatic speaker and room calibration system with six parametric equalizers, and a slightly higher power rating. The next step up AVR 2805 ($899) is the still similar AVR 2105. It has a more complex Denon power amp which produces lower distortion. It has even more I/Os and a DAC with a _ bit better distortion typically and a specified worst case distortion limit (the DAC on the AVR 2105 does not have a worst-case limit).