Saturday, 24 September 2016

Bi-Amping with Marantz NR-1506

Over the past 18 months, a secondary system has been evolving in our family room. We don't always feel like firing up the Home Theatre, especially during the summer, or for sports where the projector is not as good as an actual TV.

I have an old 40" Sony Bravia HDTV in there, along with a pair of B&W CDM-1NT speakers and a REL Q200E subwoofer.

We only use stereo in this room, with the system used about equally 1/3 TV watching, 1/3 movies and 1/3 music listening. Sources are a Gigabyte Brix HTPC running Kodi and used occasionally for Netflix as well as an eir Vision IPTV box (this is part of our home phone/broadband package from eir and is essentially a belt & braces second TV source just in case anything goes wrong with whole house TV via TVHeadend and Kodi).

Recently, this system has been amplified by an old Primare P30 a/v processor and an Emotiva XPA 2 amplifier. The P30 is on it's last legs and has really noisy digital inputs which necessitated using an Arcam rPac to feed usb audio from the HTPC. Plus, the Emotiva was really too much for this system and two big boxes were not doing me any favours in the WAF stakes.

We're planning on getting an Xbox One S in the next couple of months.This set me thinking about 4K content and what I'd need to facilitate this. Obviously, a TV is on the cards, but with an extra source and 4K requirements, I needed to look at amplification as well. (The Primare didn't even have any HDMI inputs).

I settled on a Marantz NR1506 receiver. I'd recently purchased an SR7010 for the home theatre and was pleased with that. The 1506 ticked a lot of boxes for this secondary system;
  • It provided 6 HDMI inputs supporting 4K Ultra HD 60Hz video, HDMI 2.2 and HDCP 2.2
  • It's got 5x channels of amplification
  • Has 2x Subwoofer outputs
  • Supports Spotify Connect and Network audio streaming
  • Works with the same app as the SR7010
  • Slimline!
  • Approaching EOL and was available on for just £275 Bargain!

All in all, everything I need for now with some room to grow.

The only concern I really had was the 50W per channel amplification rating. My speakers are rated 50 - 120W so I had some concern that there may be challenges driving them. We don't listen too loud in this room but with 300W on tap from the outgoing Emotiva, this had never been a problem.

I was somewhat comforted when I got the unit in-situ and wired up. Indeed, ongoing listening over the past few weeks has confirmed that the NR1506 is a fine solution and sounds great in stereo mode with my speakers and sub.

However, I couldn't help wondering if there was any more.

The NR1506 does not support bi-amping or second zones but since my CDM 1NTs have dual binding posts and are bi-ampable, I though it would be neat if I could use some of the spare amplification channels to drive the tweeters while having the front left and right channels dedicated to the midrange.

The receiver does have a multi-channel stereo mode. This is designed to play the same stereo track on all speakers in a 5.1 setup. Kind of like a party mode or pseudo-surround.

My thinking was that I could use this mode to force the unit to use 4x amps in stereo mode rather than two. And it works!

I now have the speaker woofers connected to the front left and right terminals and the tweeters connected to the surround left and right. There's definitely an increased air-iness to the music output and it certainly goes louder than before (around 50 on the volume dial is plenty loud whereas with just two amplifiers employed, I'd have it up at 60 or 65 before people would shout stop.)

The downsides are that this configuration forces stereo (2.1) only - I won't be able to run a 5.1 array, but that's not a requirement in any case.

Other negatives are that the only mode the system can run is is multi-channel stereo which likely means there's a deal of processing going on. Stereo or direct will cut off the surround amplifiers and result in a muddy mess playing through the woofers only.

Finally, I cannot run the Audyssey calibration routines or any of the auto-setup functions as I'm sure they would get very confused!

All in all though, I'm thrilled that this works. There's no timing issues which I though might be a problem and I'm confident that there's a little more headroom in the amplification to my speakers.

To set this up, I had to go into the receiver settings and configure the front and surround speakers. This allows multi-channel stirrer be selected as a music mode. Additionally, I went into speaker distance settings and confirmed that all speakers had the same distances to ensure no time alignment issues.

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