David & Deb's Digital Loft

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This topic contains 8 replies, has 3 voices, and was last updated by David Snyder David Snyder 3 months, 1 week ago.

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  • #4783
    David Snyder
    David Snyder
    Keymaster

    I was fortunate to have a good mentor during my formative audiophile years as a teenager. One of the best pieces of advice Larry gave me was to buy the best loudspeakers and phono cartridge I could afford. With the possible exception of the room, these are generally the components that have the most influence on system performance.

    Fast-forward thirty or so years later, that advice still has influence over my current system design; however, the source is a PC transport and USB DAC instead of a turntable. Components of our dedicated stereo playback system include:

    PC Transport: Quantum Byte Fanless PC
    DAC: iFi micro iDAC2
    Preamp: Emotica XSP-1
    Poweramps: Wyred 4 Sound mAMPs
    Loudspeakers: Legacy Audio FOCUS SE
    Power Conditioning: Chang Lightspeed CLS6400 ISO and iFi iPower
    Room Treatments: ATS Acoustics
    Digital Room Correction: AudioVero Acourate
    Software: JRiver Media Center and Fidelizer Pro
    Media Storage: Synology
    Power Cords and Interconnects: LAT International and Emotiva
    USB Cables: iFi and XLO

    Loft

    The FOCUS SE  would not have been my first choice for a 15.5ft x 10.1ft room; however, we moved these from a much larger space in Georgia, and I was not ready to part with them! Thankfully, the ATS room treatments and Acourate digital room correction combined have been enough to make them disappear.

    These recordings (captured live from the sweetspot using a Zoom H4n Pro handheld audio recorder) are a poor facsimile of how the room actually sounds in person, but check ’em out anyway:

    Walking on the Moon
    (Great dynamics in this hard to find cover of a Police song)

    The Way You Look Tonight
    (Large sound stage and hall reverberations for everything except the percussion. Still a fun listen!)

    September in Montreal
    (Nice dynamics and vocals–no wonder this is a popular demo track)

    Fields of Grey
    (May not be your cup of tea, but the entire Converting Vegetarians II album from Infected Mushroom is a delightful listen strictly from a sonics perspective).

    Tocatta
    (Old standby, but holds up well)

    The Royal March
    (The “Transients” demo from the popular Checky demo disc)

    Keith Don’t Go
    (No demo is complete with out this popular track from Lofgren)

    I enjoy both hearing other member’s systems and having folks over at our place for listening sessions. If you’re near North San Jose / South Bay and would like to hear this system, don’t hesitate to ping me. Gmail is probably best since sometimes forum updates get lost.  I’m dsnyder0cnn at gmail.com. Looking forward to getting to know more folks from the club. Thanks for having a look. Cheers and happy listening!

    — David

  • #4788
    Alón
    Alón
    Keymaster

    David & Deb: Nice system you guys have. Making large speakers disappear in a small room takes some skill, patience and experience, which you obviously have. I’d love to hear your set-up one day.

    Thanks for posting your musical selections as well. Please resubmit these great recommendations to the MUSIC forum if you get a chance!

  • #4796
    David Snyder
    David Snyder
    Keymaster

    I mentioned in my room description that I use digital room correction. Of course, we had a club event that discussed this in detail, but if you have questions or are interested in testing the waters to see if this technology could be beneficial in your own room, don’t hesitate to ping me.

    One of my favorite features of DRC is that system tuning and experimentation become essentially free. I mean, it’s always “free” to re-tune your system by tweaking positions of your listening chair and loudspeakers (“free” as in “free workout”), but with DRC, you can make subtle yet meaningful adjustments of a few fractions of a dB to your target curve that can improve the listening experience without leaving the comfort of your listening chair.

    My process is to make a backup of my target curve and FIR filter files and then create a new curve and try it for a few days. These changes are typically rather small, so an A/B comparison is not likely to be helpful. Plus, how I feel about how thigns sound changes depending on how relaxed/rested I feel at the moment. Instead, I monitor my natural response to the music–if I find that I’m listening to more albums straight through and/or having longer listening sessions than I did with the previous curve, that usually means that the adjustments were in the right direction. If I’m skipping around more and “Audiophile attention deficit disorder” is taking hold, I probably need to go back to the previous target curve and start over.

    Although I had been very happy with my current target curve for several months, a friend who mixes electronica had a listen and found that for some of his work, there was not enough energy and impact in the bass, so I thought it might be fun to experiment and see if I could bring up the bass a bit without messing everything else up. Not as easy as it sounds…it took about ten iterations to come up with a new target with somewhat stronger LF that sounded completely natural across the entire range, but I think I’ve done it. Here’s a graph that shows the old (in red) and new (in green) target curves:

    Old and New Target Curves

    All of the changes within the audible band are less than one dB from the previous curve, yet the difference is profound. If you’re into digital photography, the best way to describe it is if you open an image into Adobe Lightroom and increase the contrast and clarity sliders by a few clicks. Individual parts and instruments are easier to follow in the mix because it just feels like they are separated more and have a more natural sense of presence and “air.” The bass, where present, is more extended, balanced, and impactful but does not draw undue attention to itself.

    The more that I experiment with target room correction curves, the closer I seem to be getting to the one suggested by Harman International:

    Harman Synthesis Curve

    I never intentionally used this curve as a reference; rather, I came by my room correction target curve through many months of gradual tweaks and experimentation that have apparently slewed my target curve into a similar shape. While I don’t believe there’s one curve that’s applicable to all systems and rooms, it does seem to be the case that this general shape, ignoring the specific amplitude values, may produce consistently pleasing results in a wide variety of rooms.

    If you’re just getting started with DRC, I encourage you to use this general shape to guide your next set of correction experiments. It may shave months off of your experimentation since you’re likely to arrive at something similar eventually. If you’re a pro at DRC, please share your target curve in this forum. Although it’s not likely to be directly applicable to any room/system besides your own, it could give folks (including me) ideas of other things to try. And if you’re just getting started with DRC or just curious about it, have a look at my blog post and let me know if I can help you take your first steps into applying technology which has (in my opinion) just in the past few years become good enough for audiophiles like ourselves to consider.

  • #4805
    David Snyder
    David Snyder
    Keymaster

    Another update: I just purchased and read Mitch’s excellent book which contained a lot of useful digital room correction tips–mostly specific to the Acourate software tools but also explanations of small room acoustics theory. If you are thinking of giving digital room correction with Acourate a try or just want to improve your understanding of the topic, this book is well worth the $9.99 purchase price:

    Accurate Sound Reproduction Using DSP

    After reading the book, if you are intrigued by this solution but not sure if you’re ready to spend ~$400 on software and another $275 or so on the other required bits without first hearing the results, don’t hesitate to contact me! I’m always happy to demonstrate the before/after results in our loft system, but I can also pack up my measurement kit and perform the measurements and corrections in your room. Although the Acourate software license does not permit me to share the FIR filters that it generates, I can apply them to a few of your favorite CDs–even burn the results back to blank CD-Rs so that you’ll have them for A/B comparisons to help you decide if digital room correction is right for you.

  • #4818
    David Snyder
    David Snyder
    Keymaster

    Here’s an interesting graph that shows the frequency response of the loft at the sweet-spot before and after correction. The target correction curve is overlaid.

    Loft before and after correction, with target

    The room was setup as well as I could manage with loudspeakers that the manufacturer states are flat +/- 2dB from 18-30kHz. However, even with seven absorption panels and four bass traps, the room was adding significant distortion to the response. As you might imagine, all of those peaks and dips were obscuring details in the music and causing the soundstage to loose focus. Correcting the frequency and step response has transformed this system and room into a surprisingly revealing listening environment…and all for less than the cost of a high-quality pair of interconnects!

    This technology has been a Godsend for me, and perhaps it could be helpful for you as well. I really hope you’ll check it out. Again, please let me know if I can help.

    • This reply was modified 11 months, 2 weeks ago by David Snyder David Snyder.
  • #4876
    David Snyder
    David Snyder
    Keymaster

    Digital room correction addresses frequency response issues of a playback system; however, if doing that messes up phase, and timing, you’ve lost your soundstage. That’s no good. An ideal room correction system should improve both amplitude and phase response, and that’s exactly what Acourate does. The graph below shows the step response of my room (right channel only, but the left channel is nearly identical) before (in red) and after (in green) relative to an ideal step response curve.

    before vs. after vs. ideal step response

    As you can see, the drivers were fighting with each other in the “before” response, but the corrected response (in green) tracks the ideal step response much more closely. The result in what you hear is that transients are crisp and arrive at your ears from all drivers at same time. As a result, the soundstage has much more focus.

    The main objection that audiophiles have had to traditional EQ and most digital room correction systems is that improvements to frequency response came at the expense of phase, timing, and imaging. With newer FIR based technology like what is used in Acourate, this compromise is no longer necessary. In fact, as shown here, FIR based systems can even improve timing in modern multi-way loudspeaker systems.

  • #5148
    David Snyder
    David Snyder
    Keymaster

    Major functionality upgrade this week: we can now stream TIDAL HiFi in the Loft with digital room correction! Here’s a blog post with more details:

    HOWTO: Streaming TIDAL via JRiver Media Center

    Pretty exciting…

  • #5426

    RobC
    Participant

    Thanks for the info on Acourate and Streaming TIDAL via JRMC.  I appreciate the time you put into documenting both topics!  I love tinkering and hope to try both in the near future.

    -rc

  • #5427
    David Snyder
    David Snyder
    Keymaster

    @RobC – absolutely! Thanks for having a look. My latest project has been spinning up Raspberry Pi 3 Model B devices that are running Roon Bridge. I now have three of them:

    • Solo – RPi3 powered by an iFi micro iUSB3.0 and connected via USB to an iFi micro iDAC2 DAC. Roon Server is running two floors down and providing access to local FLAC, TIDAL, and applying digital room correction filters using Roon’s convolution DSP.
    • Amped – RPi3 with a HiFiBerry AMP+ GPIO hat. This DAC/amp card is only capable of 44.1kHz (as far as I can tell) but also provides 25wpc of amplification. It’s running Roon Bridge and driving an old pair of JBL 4311B studio monitors.
    • DAC’ed – RPi3 with a HiFiBerry DAC+ Pro GPIO hat. This DAC has independent low jitter clocks for 44.1kHz and 48kHz time bases. It’s 24-bit, 176.4/192kHz capable. It’s also running Roon Bridge and still burning in. Initial sound tests are promising…very impressive performance for its tiny price. May be improved by power upgrades.

    Here’s a link for more details about the first of these three builds:  https://blog.dsnyder.ws-e.com/index.php/2017/03/19/raspberry-pi-3-for-roon-bridge/

    Cheers!

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