Audiophile small room acoustics: complex and essential.

In the post "What are the most important audio components?" a few years ago, I said that we need to understand the various audiophile "domains": audio hardware, room acoustics, quality of your music, and of course personal mental engagement. Each of these have a part to play in the achievement of and personal judgment around sound quality.

Of those domains, it's hard to speak about personal mental engagement as this is a highly individual exercise (and related to one's auditory acuity). The quality of the music we listen to again is related to not just personal preferences (like genre) but also what mastering quality and variants like hi-res, multichannel, and on what format (SACD, vinyl, etc.) the record label makes available of our favorite albums.

It's always tempting of course to get excited about audio hardware - the latest toys. For example, recently, I heard that Andrew Jones has another ported box speaker design with paper/fabric drivers, this time with a coaxial tweeter+midrange that's based on field coils / electromagnets, paired to the permanent magnet woofer at something like USD$34k. While I'm sure this could be a compelling design for many, I think we can also recognize that these days, as equipment fidelity has improved significantly to the point where a simplistic "high price = high quality sound" equation no longer works, it's maybe wiser to direct our attention to the other domains.

This then leaves the very important issue of sound room acoustics, an area that we can all to some degree optimize (see also previous discussion on the sound room). I have heard it said that the sound room is the "foundation" from which we build our hi-fi sound system. As with any project, without an adequate foundation, no matter how great the rest of the system may be, you can only achieve a ceiling of performance dictated by the limits of that foundation.

In this post, let's dive a bit deeper into the importance of typical domestic small room acoustics and general principles around achieving good sound quality.

miniDSP UMIK-2 USB measurement microphone (also ambient noise floor, measurements of my system using Dirac Live with Paradigm + SVS subs)

Well, as mentioned previously, it was a great holiday season and here's another gift from Audio-Santa 🙂 - the miniDSP UMIK-2 measurement microphone. I bought this through Solen.ca here in Canada and they did a great job with the order and quick shipment. Amazon Canada often has limited stock of miniDSP products.

I'm sure the miniDSP company is well known to many audiophiles at this point. I bet many of you, like myself, already have one of their UMIK-1 microphones which I've used in a number of the acoustic measurements on this blog since 2019.

As you can imagine, the UMIK-2, initially released in late 2020, is an evolution of the UMIK-1 with upgrades which we'll talk about. First, let's have a peek at the physical device itself.

More Bass: The SVS SB-2000 Pro subwoofer (sealed, 12", 550W, DSP, Bluetooth)

Over the holidays, Santa brought me a new SVS SB-2000 Pro subwoofer (currently US$900 black ash, US$1000 piano black, Canada: black ash, piano black) for the system in the sound room. As you can see, I got the slightly more expensive shiny piano black version. As usual, I bought this from typical consumer channels.

On this blog, we've talked about full-range sound, including the importance of subwoofer(s) in order to experience "fully" all there is in our recordings. As a pop, rock, electronica, orchestral, movie-lover, the ability to experience down to 20Hz (even a little lower into "infrasound") with adequate power, and low distortion is all part of what it means to achieve "high-fidelity" audio that is transparent to the source recording. As usual, it doesn't mean I can't enjoy my music without these sub-bass frequencies! It's just nice to know that I'm not neglecting content present in those lower registers as provided by artists and audio engineers.

During the pandemic, in the spring of 2020, I bought myself an inexpensive 8" Polk PSW111 to use as an "accessory" subwoofer to help fill-in the bass response in concert with the mighty Paradigm SUB1 (1700Wrms, 6 x 8" drivers), my main subwoofer that achieves frequency response down below 20Hz. For these last 5+ years, the little Polk has done its job reasonably well but it clearly has limits. For example, when pushed up in level, I can hear the "chuffing" from the small ~4" diameter down-facing port. Also, a ported 8" sub like this can really only be expected to reproduce down to the mid-30Hz at best.

And so, moving ahead, let's spend some money to retire that little Polk sub to my main floor living room, making space for this SVS! 😁

Dirac Live 3: A look & listen with the Integra DRX-8.4 - the process, microphone placement suggestion, tweaking, and multichannel/Atmos results.

As discussed years ago with my sound room set-up, I believe room correction DSP is very important and has become part of my routine whenever I make significant changes in room layout or when I incorporate new equipment. I would argue that an audiophile who has not seriously spent time trying this likely has not heard the best sound in their room from their system. Simply put, you'll notice a level of control and audible difference way more than just swapping hi-fi DACs, amps, etc. hardware.

With the arrival of the Integra DRX-8.4 receiver recently, I started using the included Dirac Live Full Bandwidth license embedded in the hardware. As I had done in the recent past with Acourate and Audiolense XO, let's dive into the steps I used to get Dirac running and the results I achieved. Hopefully this discussion could be useful for those of you thinking of trying out Dirac.

I'll document the steps I followed, issues I ran into, and tips to overcome problems.

SUMMER MUSINGS: What are the most important audio components? Domains / dimensions of the audiophile pursuit.

[Available as audio podcast summary.]

The other day, I came upon another common question we run into within the audiophile forum communities. The thread topic on the Steve Hoffman Forums read: "What is more important? The quality of the source devices or the quality of the amp and speakers?"

Among the pages, in response to the question, there was this one listing items as such:

1 (tie). Source material, i.e. the recording, the mix and master, etc.
1 (tie). Speakers
3. Your hearing
4. Analog source playback device
5. Your room
6. Your mood
7 (tie). Digital source playback device
7 (tie). Amplification

A good list to start with! Let's spend some time in this post thinking more about this, adding more details, and broadening it out. Clearly, this (and variants of this) topic is one of those "classic" big-picture questions that demand a more nuanced and complete take. Specifically, let's make sure to contextualize the response with what I believe are relevant dimensions or domains to include.

SUMMER MUSINGS: The Soundroom - speaker layout, vibration control & correction. (And importance for the subjective reviewer!)

I thought before summer's over, it was time to "shoot the breeze" again and talk generally about a very important topic that affects all of us audio enthusiasts with what I hope are some practical suggestions from my own "journey" here at home.

The image above of a room set-up came from an article back in 1960 entitled Room Acoustics for Stereo by Abraham B. Cohen (Electronics World, January 1960 - make sure to also check out Part 2 here from February 1960). This was a time when many homes were still transitioning from the monophonic single-channel era to the bold new world of stereophonic "3D" playback with an opportunity to virtually experience an actual soundstage in the comforts of the living room. Those must have been exciting times, perhaps comparable in my lifetime to the late '90s with the release of AC3/DTS receivers providing discrete multichannel home theater.

As you can see from the pair of articles, already back in 1960, the groundwork had been laid out for what constitutes conditions for good "stereorama" sound. Best practice tips to achieve a sense of realism, the variables related to speaker placement in a room, angles to target for from the sweet-spot, distance between speakers and orientation like toe-in. Room characteristics like absorption characteristics of materials, reverberation time, room layout were discussed as well; all this informed by decades of professional recordings and studio design that came before.

MUSINGS / MEASUREMENTS: Multiple subwoofers to reduce nulls. The USB/UFO faithful. And thanks for the blind test submissions!

A few weeks back, I ran into this interesting article - "Is the room the most important component?".

In summary, it seems like the article is basically saying that we can rearrange our gear or perhaps treat our rooms in ways that sound good, thus making the room less important than a general consensus might suggest. There seems to be an undertone of trying to downplay the role of the sound room and suggesting that one can spend more money on high quality gear and still benefit. OK, sure, to some extent that's true; but there are obviously limits. After all, if the room is way too small, cubical, highly reflective and impractical to treat, speakers inappropriately shoved deeply against walls, or if there is no space behind the seating position, there's obviously no point spending $$$$ on gear that one can barely appreciate! In my opinion, the quality and size of the room and quality of the gear (especially speakers) should be reasonably balanced.

IMO, without doubt, the room does play a major role in the sound quality; I think it would be silly to suggest otherwise even though I have heard some completely deny this over the years! For example, objectively we can easily show the nodes (nulls) and antinodes (peaks) resulting from reflections and standing waves in our small domestic listening rooms. Subjectively, these effects/limitations are easily audible as well. The way we arrange the speakers will interact with the inherent properties of our listening room in ways much more significant than much of the concerns "hardware audiophiles" often speak of or obsess over (like which CD player/DAC/streamer/server we use, cable differences, or if jitter even is audible :-).

The above should be obvious to readers already. Over the last month, with "social isolation" in place, there was time after work to try out something I've wanted to play with for awhile. Let's see if I can smooth out the low-frequency response in my room by experimenting with the use of an additional small subwoofer...

Updated Room MEASUREMENTS & MUSINGS on Importance of Sonic "Accuracy" and the Audiophile.

Chapter I: Another Round of Room Measurements...

Recently, I acquired some more LP's, got a few more IKEA Kallax storage units for said LP's and put up some art as well. Here are front and rear shots of the sound room the other day...

With the physical changes and reviewing my post from last year regarding the use of (((acourate))) along with suggestions made by Dr. Uli Brueggemann and Mitch Barnett (aka Mitchco), I decided that it was time to re-do the room measurements and see if I can incorporate the important suggestions - 48kHz sampling rate for the measurements, sweep range of 10-24kHz, and incorporation of the subsonic filtering at 15Hz. If you're wondering, the dimensions of the room are ~20' x 15' x 8' with a slight frontal tapering as shown; not a huge room by any means and not ideal dimensions but at least it's not squarish/cubish (here's a study on room dimensions and acoustics). It's in the basement of my house, built as a family media room with extra thick walls to reduce sound leakage when the kids are asleep at night (I pretty well can run the sub at reference levels with kids asleep upstairs at night so long as I close the door to the basement). The main speakers - Paradigm Signature S8v3's - are 7.5' apart up front, and the sweet spot is approximately 9' from the speakers arranged like an isosceles triangle. I make sure there is decent amount of space between the couch and the rear LP storage (>3'). [As you can see, I have the ~15-year old rear full-range Paradigm Studio 80v3's back there.]

MEASUREMENTS: Sound Room Update, Digital Room Correction (DRC) and JRiver DSP Studio...

Many years ago, back in 1992 to be precise - the year Windows 3.1 was introduced, when the typical PC was running below 33MHz, and Mortal Kombat 1 was hot in the arcades - I vaguely remember reading this article from Stereophile and filed it in my memory banks as something from science fiction for another day (I heard my first MP3 compressed song soon after and thought it was amazing given the data compression!). In it, Peter W. Mitchell reportedly "heard the future" and was clearly impressed by the technical wizardry of what a "Digital Signal Processor" could accomplish. The power of the digital room correction was described as "mind-boggling". If you haven't thought much about digital room correction, I would highly recommend reading that article in its entirety and consider whether the arguments make sense to you. I don't recall reading anything further about AudioSoft or whether Snell eventually created this cartridge-based "black box" audio correction system, but as we fast forward to 2015, we are living the legacy of what was described.

These days, DSP techniques are commonplace. As digital has long supplanted analogue as the preferred method of encoding our audio and video media with high fidelity, it has all become data that we can examine and modify as we desire depending on the situation. Compress to MP3 for times we don't need highest fidelity? No problem... Resize from 1080P to 720P for the cell phone screen/storage? By all means!

Explicit uses for improving audio quality include audiophile offerings like DEQX and Lyngdorf (including McIntosh MEN-220), some products like the Devialet amps include their "Speaker Active Matching" correction filters, and the home theater crowd have been using Audyssey and the like for years.

It is interesting these days then that DSP room correction is primarily the domain of home theater and AV receivers, rather than high-end audio. In fact, reading certain "high end" audio forums suggest a stigma against DSP techniques to improve the sound of an audio system. Among audiophiles, it's not unusual to see suggestions around listening to tubes, turntables, and vinyl LPs as providing some kind of elevated audiophile experience, but I've ironically experienced the cynicism when you bring up the idea that digital room correction is important if not essential as a very desirable way of improving the high-fidelity experience.

MEASUREMENTS: Room acoustic absorption panels... (GIK Acoustics Freestand)

"... of course you realize it won't sound exactly the same in your listening room, sir ..."

In the last few months, I've been doing more with REW measurements and examining the acoustics in my room, culminating in implementing digital room correction with my computer audio playback. It is because of this that I made the posts recently looking at speaker cables and the effect of speaker grill(e)s. Along the way, I also measured the effects of a couple of simple acoustic panels I have in the room to objectively examine the outcome.

MUSINGS: Silence (Is Golden)... [HTPC Rebuild]

A couple weeks ago in the post on the Philips Golden Ear Challenge, I touched on the topic of hearing acuity and the importance of this. It's one of those things that seems to be taken for granted in the press and in audio blogs/reviews as if everyone who writes on high-end audio is capable of these feats of perception.

This week, I thought it would be useful to consider the topic of "silence". Music grows out of silence. Without silence - or to more accurately put it; a low noise floor in the listening room - it would be difficult to detect very slight "microdynamic" changes. Even if one were to pump up the volume, nuances can be missed. In part, this is why the "dreaded" dynamic range compression (volume compression) is used. It reduces the dynamic range such that even very "soft" detail is pushed up in volume allowing detection of these details on the subway and in cars (remember back in the day when we had "loudness" buttons on car music players?), as well as qualitative psychoacoustic preference to some extent. There is a limit to how far volume can be pushed in that at some point, we experience the sound to be intolerably loud or the hardware starts distorting - remember to always protect your hearing. Important characteristics of accuracy in reproduction - tonal neutrality (uncolored), and precise conveyance of detail (combination of good dynamic range & timing accuracy) - demand that the room be isolated from external noise as much as possible. It'd be a shame to listen to high quality audio at reference 75-80dB level but 50dB of that is affected by noise! Even worse than consistent background hissing, humming, or rumbling is random or episodic noise like frequent cars passing by or people talking outside distracting the virtual "concert".

Refer to the "Sound Pressure" Wiki page with the relevant levels at the bottom. For convenience, I've reproduced it here:

Not on the list: AT&T-Bell "Quiet Room" = 10dB(A). Orfield Labs "quietest place on earth" as per Guinness = -9.4 dB(A)!

Nobody (that I know of!) advocates listening to music in an anechoic chamber of course. In a domestic sound room environment, your best bet for a quiet room would likely be in a basement behind closed doors unless one listens in the dead of night away from street car noise and domestic hustle and bustle. The professional standard for ambient noise is usually around 20dB(A) for the recording studio (check out this EBU Tech 3276 document for the gory details). As indicated by the red asterisk in the chart, we should try to aim for a very quiet 20-30dB SPL in the listening room; similar to the environment that the pro sound engineer would use as the reference.

In my home, as I mentioned last month regarding the HTPC in my sound room, I could still hear the hard drives spinning in that computer. A bit annoying, and this just won't do :-). So I decided to rectify the situation doing what I suggested in that post - separating the music/movie/data server component to another room and putting together a relatively low cost, less powerful computer which could act as a streamer. I extracted the fanless power supply from that computer and reinstalled the SSD with Windows Server; moving it into an adjacent room. Here are the pieces then for the new build:

Case: Bitfenix Prodigy M microATX
Power supply: transplanted the fanless SeaSonic SS-400FL2 400W
Motherboard: ASUS B85M-E/CSM - has HDMI with 4K capability
CPU: Intel Pentium G3220 (dual core, 3GHz, 54W TDP only, Haswell graphics features but slow 3D)
CPU Cooler: CoolerMaster Hyper 212 Plus (total overkill but lets me run almost fanless!)
SSD: Corsair FORCE 240GB (got a good deal on a refurb)
RAM: 8GB Kingston DDR3 1600 (note the G3220 will underclock this to 1333)

I installed Windows 8.1 Pro x64 on the system. Due to the oversized CPU cooler, I'm able to run the 120mm fan essentially silent between 20-30% speed and this is the only fan in the whole unit. No problem running 50 iterations of IntelBurnTest without any errors at "Very High" stress level while staying cool (I like using this program for stability testing more than Prime95; generates lots of heat within minutes).

So far, I've streamed a couple of MKV 1080P movies in excellent quality 20Mbps H.264 plus DTS soundtrack - no problem at all. I also installed JRiver 19 and foobar as I described in that last HTPC article and have no problem streaming DSD64/128 to the TEAC UD-501 using USB2 and 5.1 multichannel FLAC to the Onkyo receiver through HDMI. The Squeezebox system (Transporter, Touch, Boom, Radio) connects directly to the Windows Server machine and has nothing to do with this HTPC.

All this is running silently with a reasonably fast machine for media playback purposes. I should be able to play 4K as well using the built-in Intel graphics off the ASUS motherboard's HDMI 1.4. I tried streaming some YouTube 4K videos and they looked great on the 1080P screen - they're decoding reasonably well without much framerate issue at least so it'll be interesting to see how smoothly (or not) they play on a native 4K panel one day assuming I'm still running this rig...

Out of interest, I decided to try measuring the background noise in my sound room using a calibrated Behringer ECM8000. Realize that this inexpensive measurement microphone is not meant for low noise purposes with a self-noise in the low 20dB range (according to this link) mainly related to the small microphone diaphragm. I'm certainly not about to spend something like $2000 to buy the AcoPacific PS9200KIT for this purpose (this can measure down to ~8dB(A)). I figure if I can get a rough estimate, it'd be good enough. So, using a Radio Shack digital SPL meter (which only goes down to 50dB) for quck'n'dirty calibration for the Behringer with REW, then letting the Behringer measure the "silence" at the optimal listening position, I'm seeing this:

Quiet room, 10:30PM: HTPC/pre-amp/monoblocks/subwoofer/TEAC DAC/Transporter/room EQ DSP all turned on.

Not bad. It can dip down to the 28's and up to ~31 over the course of a few minutes of measurement. Good enough as a ballpark estimate aiming for the 20-30dB target. Using C-weighting (which is a more linear response profile vs. A-weighting which corresponds to human hearing), I'm seeing ~33dB(C). Prior to this new HTPC build, I was seeing about 35dB(A) with all those hard drives spinning.

Even though the ambient noise level is low, my room still has not been treated with acoustic panels so the room reverberation time remains a bit high. EQ'ing has provided a reasonably flat response described previously (+/-5dB around the target Brüel and Kjær "house curve" with recent digital EQ tweaks). Absorptive acoustic panels remain on my radar screen - I'm still contemplating aesthetics.

Happy listening everyone. Make sure to take a minute and consider the "sound of silence" in your audio room...

-----

I want to end this post on a more serious note (as much as I enjoy the topic of audio, it's only a hobby after all!)... I want to send my regards to Matt Ashland, the CTO of JRiver, the principle developer of Monkey's Audio (APE format - probably the most space-efficient free lossless compression system), and contributor to the DoP protocol (DSD over PCM). As some of you know, he had a fall in January and required surgical evacuation of intracranial bleeding; still recovering in hospital. I had the pleasure of exchanging E-mails with Matt last year around the time of the beta JRiver 19 release regarding the PCM to DSD transcoding algorithm, DST decoding, some bug fixes to JRiver, and his summer vacation with his kids. A truly genuine, generous gentleman and one of the unsung heroes of the computer audio hobby... My thoughts and prayers are with you and the family, Matt. Get well soon.

Matt has a CaringBridge page.

ADDENDUM: (March 7, 2014)
For those wondering, even with the Pentium G3220 underclocked to 2.5GHz, undervolted by -0.1V to consume <30W under full load with IntelBurnTest (~36C after 30 minutes), there is no problem upsampling 24/192 PCM to DSD128 in realtime with JRiver 9. CPU utilization <30%. I had to increase the TEAC DAC's ASIO buffer to 250ms to prevent some buffer issues though. Sounds great...

Given the price and performance of this CPU, I can't imagine any reason to build anything less powerful these days. I think it would be no problem running this fanless with a good sized heatsink if I underclocked it even further; 2GHz dual core with lower voltage fanless probably would be totally fine!

Room Measurements First Steps (Stereo): Paradigm's PBK-1 and Room EQ Wizard...

PBK-1 mic about to record some subwoofer beeps and boops...

Alas, the Christmas & New Years holiday season is behind us. Each year, I'm amazed at just how quick everything goes by... Never enough time to enjoy the music among the rest of life's other demands.

I didn't get much time off but I did manage to try out some room measurements in the evenings when the kids were in bed.

For all the time I spend thinking about audio components, it's unfortunate that I've spent too little on the room itself. With the new house and room, I hope to change this. Remember folks, as much as "we" (audiophiles) might obsess over the quality of our DACs or (some) might sweat over things like (supposed) cable differences, without question, the quality of the transducer/room interactions trump essentially any of the other factors in the audio system given the quality of electronics these days. Frequency variations in the audio room can fluctuate wildly, on the order of magnitudes of difference compared to the rather trivial differences between DACs for example. It might not be cool or sexy to speak about bass traps, diffusers and absorbers versus DSD or fancy cables made of Unobtanium, but this is what's ultimately going to make huge differences.

Of course, room measurements are not a new topic... Many excellent web pages have been devoted to this. For room treatments, check out Ethan Winer's RealTraps site. Also, Mitchco's excellent room calibration article not long ago documented his procedure nicely.

I'll have the years ahead to add hardware around the room, but as a first step, I'm just going to try the simplest of "room corrections"; EQ'ing frequency response using DSPs.

I. Paradigm PBK-1 (Perfect Bass Kit)

Paradigm, Anthem, and Martin-Logan are owned by the same parent company and share similar technologies in terms of room correction. The Paradigm Signature and Martin-Logan subwoofers have built-in DSP units that can be programmed using a PC with the PBK kits; based off of the Anthem Room Correction algorithms. As the name implies, this kit is used for bass correction only as it applies to the subwoofer. Audio levels still should be checked with the rest of the system in order to make sure the sub integrates well.

As of this writing, the current version of the PBK software (2.01) is not compatible with Windows 8 (even with compatibility settings)! I had to dual boot the old laptop used for measurements with Windows 7 and run the software through that... Paradigm, please update the program!

The software was easy to run and essentially self-explanatory. A USB cable connects the included PBK microphone (shown above) to the PC, then another USB connects the PC to the subwoofer. Each microphone has been calibrated and identified by serial number in the software. The program is capable of measuring multiple locations (max. 10) in the room to smooth out the bass response. Since I'm most concerned about the "sweet spot" and want to limit the potential of suboptimal calibration, I took 5 readings all around the central seat and the 2 adjacent seats. The program then will run thorough the calibration algorithm and show a screen that looks something like this...

You have the option to adjust the DSP crossover frequency point which in the graph above I've set to 160Hz (default is 250Hz) as well as how steep the filter should be. This gives you some customization options (not much).

The red curve was what I got in the room. As you can see, I have quite a dip at around 65Hz (red) which was correctable to some extent (purple). The peaks (eg. around 30Hz correlated to the calculated lateral mode for the room size at 29.1Hz using this online calculator) were easier to correct, and it's nice to see good frequency response down to 20Hz with this sub. (Check this link out for the room mode math calculations.)

The program will automatically upload the new settings to the subwoofer and away you go... Very simple calibration to do.

II. Room EQ Wizard (a.k.a. REW)

REW (5.01beta) can be downloaded free off the Home Theater Shack website - just need to register. It's just an amazing piece of Java code for the audio enthusiast.

About 3 years ago, I purchased a calibrated Behringer ECM8000 mic (I see they don't sell these calibrated any more at this site). This microphone has served me well over the years and put to good use here again (note that I actually measured it a little lower at ear level sitting on the couch than the picture below):

Using the EMU 0404USB as measuring ADC, here's the raw room response with just the PBK settings in place for the subwoofer integrated with the main front speakers (1/6 octave smoothing) using the TEAC UD-501 DAC:

Although I don't know if I fully trust the Behringer mic below 30Hz and above 15kHz, it's good to see frequency response down to 15Hz. Again we see the room mode around 29Hz. The deep blue line represents the eventual target curve we're aiming for based on the default REW house curve (for those looking for the excitement of a bass-induced thrill ride, try this target curve). For those looking for more based on home theater wisdom, check out this link on House Curves and more!

Letting REW perform its own EQ from 20-200Hz plus a few small adjustments on my end resulted in this mathematical prediction of room response:

Much more controlled on the low end using 7 parametric EQ settings (you can see the numbers above) plus 2 settings at 3kHz and ~11kHz to roll off the top. Total of 9 EQ settings were programmed into the Behringer DEQ2496 applying the adjustments in the digital domain and looped back to the Transporter for DAC duties.

Since some frequency boosting is involved, I reduced the DEQ2496 digital output levels by 6dB and double checked with some really LOUD music to make sure the EQ settings did not lead to clipping. The 1997 Iggy Pop insane remaster of The Stooges' track "Your Pretty Face Is Going To Hell" off Raw Power is a good one - average dynamic range value of 1dB for the album! If the DSP processing doesn't clip with that track, it's probably not an issue with >99% of my music.

Since it's always good to confirm that the EQs are actually doing what they're supposed to, here's the actual measured room response with & without the Behringer DEQ2496 played through the Transporter as DAC (measured at a higher level on a separate day):
Before REW EQ:

After REW EQ:

OK. Nice real-world confirmation that the EQs are doing what they're supposed to. The predicted results checks out even with a different DAC (measured with TEAC, confirmed with Behringer & Transporter - I knew from previous measurements that the Transporter is very close in frequency response to the TEAC)!

Looking Ahead...

Like I said above, I have many days ahead to make this room "work" better acoustically. EQ'ing so far is just the "quick and dirty" first step at this point focused essentially just on volume equalization (although I guess the PBK might be doing more in the algorithm). I haven't even begun to try using the Audyssey MultEQ XT for multichannel yet (in the Onkyo receiver), nor room treatments...

Regarding room treatments, there's much to do! Here's the measured waterfall spectral decay plot in REW:

15Hz - 20kHz

20-200Hz

With EQs in place, the decay time of course remains high:

15Hz - 20kHz

20-200Hz

Plotted at 500ms duration down to 40dB with 1/6 octave smoothing, I'd really love to see more uniform steeper decay (<<300ms). Bass traps in the corner and absorption panels to the sides at the first reflection points could do the trick. Hmmm, maybe this will be a project for Spring Break - whip out the saw, stapler gun, make some wood frames, grab fabric and a stash of Roxul Safe'n'Sound :-).

There is also the issue with time alignment as addressed by mitchco using Acourate and convolution filters. That's another level of tuning I'll have to leave for another day! So much to do, so little time...

For now, the subjective sound quality has improved. There's already notably better control to the bass notes from Rebecca Pidgeon's "Spanish Harlem" (to use a well known audiophile favourite). Time to just sit back, relax, and enjoy some tunes! I've got a couple of ideas for tests coming up.

Musical selections recently:
- Daft Punk's TRON: Legacy soundtrack (2010) on Blu-Ray was stunning! I missed the movie in the theaters and rented the 3D Blu-Ray the other day... The movie itself was OK but the surround effects and techo score really made the movie an audio feast.

- The Eagles. Love 'em or hate 'em, I reacquainted myself with the multichannel DTS version of Hell Freezes Over (1997) the other night. IMO another fantastic multichannel release from the earlier days of surround sound when DTS was releasing their DTS-CD's (this was also my first concert DVD). That live ambiance really shines through as if you're sitting in the audience that night. The guitar work and percussion sound great in the new system on "Hotel California" - especially the bass impact. I saw them in concert about 3 years back and that too was a blast.

- Speaking of bass... I don't often buy modern pop recordings but I did enjoy listening to the recent album by Lorde - Pure Heroine. Fantastic job by the 16-year-old from New Zealand. The current Top-40 'hit' "Royals" gives a nice taste of the cavernous bass found throughout the album ("400 Lux" is another to check out). Have a listen to this album through a system with clean bass down to 20Hz and see whether you think you need a subwoofer :-).

Addendum:
In the "Answer To What Question?" and "What Were They Thinking Of?" files... I was looking at the recent CES2014 announcements in the usual audiophile watering holes and found this:
Esoteric Grandioso D1 Monoblock DAC
Given the level of performance of even modest DACs these days, I really can't imagine what would be the reason to go monoblock with a DAC. Seems like doing this could make things worse (channel desynchronization? need for DAC matching?) and at a significant expense ($22,000 each, not to mention all those extra cables!). Small price to pay to feel grandioso I suppose. As usual, would love to see the measurements for a pair...

MUSINGS: A Look At The Sound Room...

It's about 2 weeks now since I moved into the new home. As expected, it was stressful; with kids in tow, it's not like the bachelor days with just one's personal belonging in the trunk of my old hatchback!

Well, for the most part, the move hasn't been horrible. And the exciting thing as I've already previewed is that I now have a good sized "man-cave" for my A/V "needs" :-). Without further ado, let me show you the setup so far:

Head on view of the main system - Transporter playing.

Angled from the side - note the SUB1 just lateral to the left front speaker. The black box closest to edge of the sofa is the computer (Fractal Design Define XL case - nice and quiet).

"Super deformed" wide angle view of the room... Rear Paradigm Studio 80s visible.

As a MUSINGS post, I'm just going to spend a few words on thoughts around building the setup. Since the start of this blog and explored briefly in this early post, I do believe that judging the quality of an audio component can be accomplished objectively; that is, there is a technically "good" or "bad" way to know whether components live up to engineered goals. As I mused in that post, the gold standard for me is not so much to reproduce the "concert experience" as some might desire, but rather the ability of the equipment to reproduce exactly what's on the CD/DVD/DVD-A/SACD/Blu-Ray - that is my definition of high-fidelity. If the CD has an ability to transport me to a faraway concert hall, then I want my equipment to be able to reproduce that encoded sensory stimulus which leads to (hopefully) my ability to experience the same. Of course, not all CD/DVD/DVD-A/SACD/Blu-Ray's can do this! The medium itself must be able to encode quality to the extent that the experience is possible and the experience itself is provided by the artist, recording engineer, mixer, mastering engineer, producer, etc... who have put their expertise and knowledge into the recording. On my (consumer) end, I'm just looking for a good enough combination of components that can take that encoded sensory experience and provide it accurately; nothing more. I do not personally believe in aiming for a "euphonic" setup where the components can make all albums sound "sweet". I'm interested in just an honest presentation of what is on the disk; if I want to add euphonia, I will happily do it myself such as the PCM-to-DSD upsampling process or re-EQ with my Behringer DEQ2496.

As with anything in life, unless I were a billionaire, there are practical limitations on how much I am willing and able to spend on a sound system. I'm happy to sink money into the pursuit but it's only one of many interests! To spend as little as reasonably possible to achieve the best sound quality (and within decent aesthetic parameters) is a virtue I strive for. My experience has been that for electronics gear, there really is very little correlation between price and the (objective) sound quality it buys. For example, there's generally very little if any audible difference between a $500 DAC compared to a $2000 DAC if they measure the same; speakers, room acoustics, amps will easily trump the sonic differences. I can enjoy the inexpensive AUNE X1 (<$200) just as much as the more expensive TEAC UD-501 (~$800) even though I know the TEAC measures significantly better. In fact, I prefer the AUNE's more powerful headphone amp when I'm listening with the AKG Q701 headphones. However, the TEAC offers native DSD playback which is the niche it fills in my system. Likewise, the Transporter is my hi-res ethernet streamer, and the ASUS Essence One lives on my desktop for computer listening on account of its separate headphone/speaker controls and beefy headphone power. Where cost does seem to correlate better IMO is with the transducer devices - headphones and speakers. For these components, I'm quite happy to sink $$$ down! For fun, here's approximately how I've allocated out the cost of the audio system (minus HTPC which is more powerful than I really need for audio purposes). Note that I did not sit down to calculate this out before hand, it just organically came to be:

Speakers (fronts, rears, center, sub): 77.5%
Digital sources (including Behringer DEQ2496 processor, Panasonic Blu-Ray): 10%
Amplifiers (including Onkyo receiver): 10.9%
Cables + Belkin PF60 power console: 2%

Alright, I'm pretty happy with those numbers - I think they reflect reasonably well my priorities. Of course, the cost that truly trumps everything is the cost of real estate in Vancouver! So, let's run over the components I have set up in the room and share a few thoughts... As usual, since this is a MUSINGS post, it's mainly an experiential discussion with opinions thrown in.

I. First, let's talk about the 2-channel signal path:

Most of my music is in stereo. Therefore good 2-channel reproduction is most important. Enough said.

Time and again, measurements of the ASUS Essence One, Transporter, and TEAC UD-501 have demonstrated the superiority of balanced cabling. Whether anyone can hear the difference of course is another issue. Balanced operation was the reason for the choice of the Emotive XSP-1 preamp as the heart of the 2-channel system. To maintain the balanced topology, I got a couple of Emotiva XPA-1L monoblock amplifiers - good price and with the option to switch over to 35W Class A bias if I want.

Squeezebox Transporter music server chain:
Win8 HTPC --> ethernet --> Transporter --> Emotiva XSP-1 preamp (crossover at 60Hz to feed SUB1 subwoofer) --> Emotiva XPA-1L monoblock --> Paradigm Signature S8 v.3

Computer audio PCM/DSD chain:
Win8 HTPC --> Belkin gold USB --> TEAC UD-501 DAC --> Emotiva XSP-1 preamp (crossover at 60Hz to feed SUB1 subwoofer) --> Emotiva XPA-1L monoblock --> Paradigm Signature S8 v.3

Although just "fast ethernet" (100Mbps) is all that's required for the Transporter, the house is wired for gigabit and I've used generic Cat-6 cables for the Transporter to the gigabit switch. I'm quite pleased that I can easily transfer >100MB/s between machines around the home. All balanced audio cables were inexpensive (but good build) Monoprice Premier XLR's from 3-6' in length. Over the months, I've used Monoprice cables to measure balanced output from my DACs and the results have been excellent, not unexpectedly.

In the same vein, speaker cables are Monoprice 12-guage "Enhanced Loud" (LOL!) OFC. Monoblock to front speakers only 4', center channel 6', rears at most 25'; cut to minimum lengths required. I bought a 100' spool for $30 and still have some left.

II. Multichannel signal path:

I love multichannel music! The realism achievable can be amazing and IMO anything that enhances the creative potential of artists can't be a bad thing. Remember that historically multichannel speaker configurations were being explored along side 2-channel stereo. 3-channel stereophonic sound was demonstrated by Bell back in 1933 and the right-center-left "3.0" arrangement was used in some of the earliest "Fantasound" systems for Disney's Fantasia when released back in 1940. Having a center speaker in a theater setting allows the anchoring of front-and-center sound which improves the imaging for those not sitting precisely in the "sweet spot". For music, likewise it helps especially for solo/vocal tracks. For example, the Analogue Productions' Nat "King" Cole SACDs like The Very Thought Of You presented in 3.0 sounds phenomenal with this arrangement with Nat sounding like he's right in front of you crooning.

More than 10 years ago, I built a discreet multichannel system based on my old Denon AVR-3802 receiver. However, I had to give up the 5.1 setup when my kids came 8 years back to make room. After many years in "pure stereo" wilderness, I'm glad to finally be back with a full 5.1 setup again! Here's how it's hooked up:

Win8 HTPC / Panasonic Blu-Ray --> Energy HDMI --> Onkyo TX-NR1009 (amplifies rears and center, up to 145Wpc 2-channel measured) --> unbalanced RCA --> Emotiva XSP-1 preamp (HT Bypass Mode with channel to SUB1) --> Emotiva XPA-1L monoblock --> Paradigm Signature S8 fronts

Center speaker = Paradigm Signature C3
Rear speakers = Paradigm Studio 80 v.2 (tonal balance complements the Signatures reasonably well)

As you can see, my rears are full range towers.  I'm aiming for speaker layout angles approximating the ITU-R BS.775-3 (08/2012) recommendation at the "sweet spot" position:

I suppose I have room for a full 7.1 surround setup with 2 extra speakers to either side using the Onkyo receiver... Another SUB1 for 5.2 or 7.2 would give insane bass! One of many projects for the future, I suppose. I am unaware of any music I want available in 7.1 at this time and I suspect a TV upgrade to something like 80" would be more likely.

III. Challenges...

In a moderately complex setup, it's not surprising to find some challenges along the way. The main thing I found was that for multichannel, the Home Theater Bypass setting on the XSP-1 was very sensitive to noise. I had to move the PC to the left side about a foot from the subwoofer and ~5' from the XSP-1 to get rid of RF noise picked up by the preamp. Also, I had to use a "cheater plug" for the LG 55" HDTV mounted against the wall to remove ground loop noise. This was the relatively easy stuff!

The most difficult noise issue I'm still dealing with now is the USB interface to the TEAC UD-501. If I have the USB cable connected, there's a high pitched whine emanating in HT Bypass mode. This does not appear to be a component ground loop issue but rather noise from the PC through the USB interface polluting the analogue pass-thru. This actually does not affect stereo playback from the TEAC, just when I'm in multi-channel mode with the XSP-1 passing through the front stereo and subwoofer channels. It's not an issue with the RCA cables since more expensive AudioQuest and Tributaries RCA cables make no difference compared to inexpensive Radio Shacks whether 3' or 6'. The simple solution for now is unplugging the USB cable to the TEAC DAC when I'm listening to multichannel. Trying other USB ports and hubs have so far not helped. I'll have to look at other options like the FireStone GreenKey "USB Isolator" or some other way to achieve galvanic isolation but maintain high-speed USB 2.0 for DSD and hi-res PCM playback.

Looking ahead, I still have to try out some frequency response measurements and subwoofer room correction with the Paradigm PBK-1 ("Perfect Bass Kit") I bought (only ~$120). I'm inspired by Mitch's experiments with Acourate so may look into that too... The room is still bare and resonant so things should also improve when the rug comes and in time, perhaps some acoustic paneling and bass traps. Not to mention some clean up and better cable management!

As is, subjectively the system sounds good despite the lack of room treatments... Of course, I am a little biased :-). The Signature S8 v.3's are the current top-of-the-line Paradigm floor standers. Good to see some positive recent reviews like this one from TONEAudio. Some might consider them too "clinical" but that's fine with me since surgical accuracy is what I'm after. A large company like Paradigm can leverage the economy of scale to maintain costs and has access to research facilities which IMO is important. The beryllium tweeters sound sweet and very realistic. The other night my wife jumped when she heard the sound of the glass shattering on Michael Jackson's Jam (surely a sign of high fidelity!). So far I've also been quite impressed with the SUB1 subwoofer. I'm easily measuring excellent levels around 20Hz. I'll post PBK-1 and REW graphs when I start doing the room measurements...

I've played around with the Class A/B vs. A settings on the Emotiva XPA-1L. Realistically I doubt I will need much beyond 30W of power through the efficient S8 speakers so I expect the amps will remain well within the 35W Class A limit (these are 250W monoblocks in A/B). So far, I cannot say I hear much of a difference although I have not specifically done any "serious" listening in Class A mode yet. It certainly does get quite warm (somewhat uncomfortable to touch) after an hour in Class A mode - as expected. Makes for decent space heaters through the holidays I guess :-).

Signature SUB1 clearly visible.

I thought I'd end off with a couple of recommendations for multichannel lovers; both of these titles are only available as DTS-CDs from the early 2000's. I've since ripped these disks and converted to 5.1 16/44 FLAC with the DTS plugin for foobar2000.

- Lyle Lovett - Joshua Judges Ruth (2002 DTS release): Folks, this is a great example of what a good multichannel mix sounds like. Lyle's voice is mostly centered up front, good use of surrounds for ambiance, some discreet vocals in the rear tastefully done. Great dynamic range of DR16. I've always enjoyed the track Church from this album (and used it as a test track for the old MP3 test). In the multichannel version, you literally feel immersed in the choir when they start singing! It's unfortunate that a proper DVD-A/SACD was not released for this album given how good this sounds (already in the DTS-CD incarnation, this album puts to shame many DVD-A and SACD multichannel releases).

- Alan Parsons - On Air (1996 DTS release): Hey, it's Alan Parsons who knows a thing or two about good sounding audio... Progressive rock was made for multichannel - especially so when conceived from the start for surround sound. Rear channels utilized aggressively on some tracks along with birds singing, and cool jet flyby special effects (check out the first track Blue Blue Sky). Again, a multichannel DVD-A/SACD release would have been phenomenal.

Until next time... Enjoy the tunes, wishing you and yours a wonderful Christmas & New Year season.

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(BTW: I got my Nikon D800 back from Nikon Canada for repairs on an autofocus issue under warranty. Wow. The focus seems to be spot on and only minimal lens fine-tuning is required now. There was quite a stir online about poor left auto-focus point accuracy as well which seems to be much better now. If you have a D800 and are running into focus issues, check if Nikon can do a tune-up.)

Getting There... (Early HT Room Setup)

Back from my overseas business trip late last week. It's going to be really busy since I'll be moving to the new house in 1 week. Massive amounts to pack up!

Nonetheless, I didn't want the movers to be involved with the audio system so over the weekend I moved all the components and put together the stereo setup in the home theater room to just have a little "taste". Here she is... (Unfortunately the image is a bit grainy. Resorted to the old Nikon D70 as my D800 developed some autofocus issues and needed repairs.)

Hmmm. Looks like I need to straightening the power/cable/ethernet outlet at the back there...

Room size is decent: 20' x 15' x 8'. The TV is a 55" LG 55LW5600 mounted on a strong wall mount - I might go for a 70" in the future. Components:

- SONY SCD-CE775 SACD/CDP I bought back in 2001

- Emotiva XSP-1 pre-amp

- 2x Emotiva XPA-1L monoblocks connected to XSP-1 with Monoprice XLRs - 35W Class-A bias, max 250W Class A/B

- Paradigm Signature S8 v3 fronts

- Paradigm Signature SUB 1 subwoofer crossed over at 50Hz

- Cables: 4' 12G OFC Monoprice zip cord speaker cables, Radio Shack 3' RCA from CDP to preamp, stock power cables

I still don't have the sofa sectional in the room and room treatments, nor have I set up the SUB 1's programmable subwoofer room correction yet with PBK-1. Despite the bare room reflections, it sounds pretty decent still... Played my old Kind Of Blue SACD, Diana Krall's When I Look In Your Eyes, and Beck's Sea Change tonight. Really liking the subwoofer's punch on the Beck SACD. I'm an advocate for a good subwoofer... Good frequency response down to 20Hz is essential for hi-fidelity IMO.

Chat later... More boxes to pack tonight :-(.