Nest Theater Part Eight - Audio Integration & Measurement 18Apr20

With the AMP compete and tested and the DAC verified I headed to Silverthorne to install all the gear in it's rightful spot, integrate it, test it and most importantly, listen. The entire 2.1 audio system is now ready and frankly one of the best digital source hifi systems I've ever heard. JRiver MC / Roku Ultra > DENAFRIPS DAC > AudioNote Kit 1 300B SET AMP > DRC BLHs with Veriwave SRT7 Ribbon supertweeter & HSU ULS 15 Mk II subwoofer. Integration was not totally simple as the DAC tended to over-deliver the low end to the sub and so careful adjusting was required. The TV delivers PCM over optical back to the DAC when Roku is streaming and JRiver on the PC uses USB to connect to the DAC. From there it's just using the DAC outputs to get to the tube amp and to the sub's amp. I am amazed at the quiet yet mind-blowing loudness I can get from this 8 watt system - super efficient. Plus, thankfully, all the gear choices yielded a very smooth, liquid and organic sound with a huge yet well-defined soundstage... and no fatigue while listening - I've now spent many hours. In fact, driven by this gear, the horns are sufficient and the super-tweeters and subwoofer are just icing. If at the Nest, do ask to listen. Now there's just the staining and finishing, and a new TV; Ill probably clean up that inter-wiring too.

I installed REW on the XPS laptop so measuring would be ever-ready and simpler than toting my Mac all over. The system on its own was awesome as you can see from the 1st SPL graph but I knew I could to even better with a little EQ - I got a very close match to my desired house curve with a dozen or so filters added to JRiver - see the 2nd SPL graph after correction. I sense I got the variability from ~5-10 dB from house to ~2-3 dB from house and importantly got rid of the shout at 1K-2.5KHz - I still have some bass dropoffs and may need to continue to work the SUB-BLH integration some.

I also compared the full system's frequency response with one captured previously when the speakers were driven by the digital NAD amp/dac and noticed that while similar, the new amp/dac delivers a smoother raw response over the spectrum but rolls off sharply @ 17KHz compared to the NAD-driven high end.

Update - I did a range of measuring & testing with two different subwoofers, each in multiple locations, and have dialed in the low end a little better. Below I compare No Sub (red) with the best settings & location for the Hsu Sub (green) with the best settings & location for an 18" Velodyne Sub (purple). While I moved the subs around, I still found no better acceptable spot than the front wall near the right BLH... I'm sure it suffers a bit from not being directly in the corner but I need the BLH there for separation and it's bass contribution. I'm not even using a crossover so the Hsu can help out all the way to ~200Hz.

 

Update #2 - I've continued to work the audio paths, especially for bass management, as the install was so delicate and finicky to control. My latest scheme measured more controlled than all prior and sounds even better as to balance with the BLHs. Shown below is the house curve with the old and new schemes - full sweeps, then the DSP corrected response. Low end distortion previously possible has been mostly eliminated (or below the noise floor) and overall volume is controlled via the single 300B SET amp's potentiometer. Amazing.

Listened to Fiona Apple's latest album - as usual, quirky good stuff including very idiosyncratic percussion throughout. My favorite track was the title cut. I caught The Strokes new drop, The New Abnormal... it's also good and more accessible to me. The New Abnormal is quite possibly the best Strokes album since Is This It. I also dove again on sad country and Cowboy Junkies are awesome... especially those first couple of albums.