Amplifier
| Onkyo TX-NR646 |
Onkyo TX-NR636 |
7 channel Amplifier: Onkyo TX-NR646 features 7 channel power amplifier. It is rated at 100 W (8 Ω, 20 Hz - 20 kHz, 2 channel driven) and is able to drive 4 ohm speakers. |
7 channel Amplifier: Onkyo TX-NR636 features 7 channel power amplifier. It is rated at 95 W (8 Ω, 20 Hz - 20 kHz, 2 channel driven) and is able to drive 4 ohm speakers. |
- WRAT (Wide Range Amp Technology): Onkyo TX-NR646 and Onkyo TX-NR636 feature Onkyo’s Wide Range Amp Technology (WRAT) circuit layout that prevents phase shifting by pushing the roll-off point higher than the listening-level frequency. Amplifying sound without phase shift creates an uncommonly well-focused and realistic audio image. If phase shift occurs and signal timing is not accurate, then neither is the resulting audio image.
Speaker Configurations
Onkyo TX-NR646's and Onkyo TX-NR636's amplifiers can be assigned for different speaker configurations.
- Dolby Atmos Configurations: The following speaker configurations are supported for Dolby Atmos:
- Onkyo TX-NR646: 5.2.2 with internal amplifier.
- Onkyo TX-NR636: 5.2.2 with internal amplifier.
- DTS:X Configurations: The following speaker configurations are supported for DTS:X:
- Onkyo TX-NR646: The speaker configurations for DTS:X are the same as for Dolby Atmos - 5.2.2 with internal amplifier.
- Onkyo TX-NR636: Not supported.
- Configurations without height channels: There are also other speaker configurations available which do not include height channels:
- Onkyo TX-NR646: 5.2, 7.2 with internal amplifier.
- Onkyo TX-NR636: 5.2, 7.2 with internal amplifier.
- 2-ch Bi-Amp: Both models are able to bi-amp up to 2 main channels simultaneously. During bi-amplification two amplifiers are used for one speaker. One amplifier powers the midrange and tweeter section of the speaker and another amplifier powers the low frequency woofers. Each amplifier is less loaded and performs better. In order to use this feature speakers must have 2 pairs of connectors.
Dolby Atmos
Onkyo TX-NR646 and Onkyo TX-NR636 support Dolby Atmos. It is a cinematic audio format in which sounds exist as individual entities, called audio objects. In Dolby Atmos, any sound can exist as an independent audio object, free of channel restrictions. They can be precisely placed and moved anywhere in your room, including overhead, to flow above and around you in three-dimensional space. Through the use of audio objects, overhead sound, and all the richness, clarity, and power of Dolby sound, Dolby Atmos turns your room into an amazing place for entertainment. The format supports up to 128 simultaneous independent audio objects in a mix for rich, realistic, and breathtaking sound. It recreates the director's original concept through descriptive metadata to provide customized playback for home theater and delivers sounds above you through overhead speakers, special upward-firing Dolby Atmos speakers, or a Dolby Atmos enabled sound bar.
- Dolby Surround Upmixer: Both models support Dolby Surround Upmixer. If the content is not mixed in Dolby Atmos then the Dolby surround upmixer will expand the audio to all channels including ceiling speakers. The upmixer has replaced the Dolby Pro Logic II family with improved upmixing algorithms.
DTS:X
Onkyo TX-NR646 supports DTS:X. A technique used in DTS:X is similar to the one used in Dolby Atmos. Instead of a fixed number of channels, DTS:X defines object locations from the listener in polar coordinates. An a/v receiver then dynamically renders sound according to the current speaker configuration. The speaker layout employed by DTS:X is the sum of Dolby Atmos and Auro-3D. It has standard 7.1 channel base layer, a 5 channel height layer above the base layer on the front and side walls, and 3 rows of speakers on the ceiling.
- DTS Dialog Control: Onkyo TX-NR646 supports DTS Dialog Control. This function adjusts the dialog levels during playback of the DTS:X stream. It allows you to separately increase the dialog levels in contrast with the background sound and hear dialog easily even under noisy circumstances.
Sound Processing
- Compressed Music Enhancer: Onkyo TX-NR646 and Onkyo TX-NR636 feature Compressed Music Enhancer which enhances the quality of the music files with lossy compression.
- Advanced Music Optimizer: Compressed music enhancement in Onkyo TX-NR646 and Onkyo TX-NR636 is done by Onkyo’s Advanced Music Optimizer. While MP3 or AAC files may sound fine through the headphones of your portable digital player, the limitations of these files can be exposed when played back through a quality home entertainment system. This is because a significant amount of high-frequency bit information is lost during the file-compression process. To counter this, Onkyo has designed the Advanced Music Optimizer to compensate for lost bit information and improve the quality of compressed audio signals. This results in a clearer and more expansive sound. Also included in this technology is a loudness correction feature that further improves the audio character of compressed files.
Room Calibration
Onkyo TX-NR646 comes with AccuEQ Advance and Onkyo TX-NR636 comes with AccuEQ room correction system.
- AccuEQ: First, AccuEQ detects the presence of speakers and evaluates the impedance of each. Next, it pinpoints their distance relative to the main listening position using the mic and sets suitable sound-pressure levels. Then it selects the optimal crossover frequency so that deeper bass rolls smoothly off to the subwoofer. Finally, AccuEQ performs frequency response equalization based on room-acoustic and speaker data collected via microphone. The sound-field is now tailored around the listening position, resulting in a more immersive and realistic in-film experience.
