Excellent Coverage of Room Correction Event by David Hicks


The recipe for better sounding sound, or “The Room is King.

By David Hicks, SFAS Director of Analog Development

I’m a believer. Even before the March 26th room correction event, I was biased in my opinion that “The Room is King.” In fact, that’s one of my favorite audiophile sayings. I was fortunate enough to discover the importance of “the room” after attending my first two Bay Area Audiophile Society (BAAS) events about a hundred years ago. I say I was fortunate because the experience of attending those two events saved me from continually spending a lot of money on “upgrading” my audiophile components in the pursuit of better sound in my main listening room.

The first BAAS event I attended was at a nice home with a system containing all top notch, very expensive gear, but the quality of the sound was decidedly ho hum. Also at that event was a former Bay Area Stereophile contributor who after hearing two tracks at the beginning of the listening session told the BAAS member his system sounded like a table radio, albeit “a very good table radio”, and that he had other things to do, and he needed to leave now, and he did. Ouch!

The second BAAS event I attended was in a modest apartment with audio equipment that I estimated costing one tenth the price of the gear that I listened to at the preceding BAAS event. But the big difference this time was the room was a more conventional shape than was the room at the first BAAS members home, and there were now acoustical panels strategically placed to mitigate 1st order reflections and standing bass waves. The sound I heard was excellent.

So, should you just go out and buy a bunch of acoustic panels and put them up around your room? Maybe not. “Treating” the room, will rarely fix all your problems. You can put up panels to mitigate problems in the bass, and end up damping out your mid and high frequencies in the process. And the option of placing acoustic room treatment in your listening space might not exist, either because your significant other might forbid it, or because you’d just like to spend time in that room without it looking like a recording studio covered with egg cartons. What to do? Worry not, there is a better way of fixing the speaker-room interaction. Read on…

I was pleased to see that The SFAS had scheduled Manny LaCarrubba as our guest lecturer for the March 26th event to discuss room correction. Manny’s audiophile pedigree extends back to The Plant, the famous Sausalito recording studio where he spent a decade as an engineer and eventually chief engineer, racking up engineering recording credits on tracks for albums by Santana, Michael Bolton, Kenny G, Celine Dion, and many others. He also designed some of the recording rooms used at The Plant. In addition to his recording work he holds patents on speaker design and has installed countless custom two track and multi-track high end audio systems. You can Google him for the full monty of his work history and accomplishments, as well as for YouTube videos that explain in detail some of the reasons why your speakers’ interaction with your room will affect the sound your ears hear more than will the other audiophile components you choose to put in that room.

In order to accomplish room correction, or as Manny prefers to say, “calibrate your system to the room” the first thing you need to do is measure the characteristics of sound reproduction in your room. This is done by playing a series of test tone frequency sweeps through your speakers while measuring the speaker output with a microphone placed in several locations around the listening area. Computer software is then used to average and analyze how those frequency sweeps manifest at the microphone listening positions. The testing is done on the left and right speakers individually, and then with both speakers together. You’ll end up with a graph like this one Manny obtained in Leslie Lundin’s audiophile garage.

Screenshot 2016-04-12 14.24.44

If you’ve been to Leslie’s Audiophile garage on a nice day, you’ll remember that the listening room on a nice day is anything but your standard indoor space. When the weather is nice Leslie will roll up the back wall (garage door) and place wrestling mats, stood on their sides, at the now open back wall. The result is that you’re listening to music in a three sided room which eliminates most of the detrimental bass problems that occur in a standard enclosed listening space. If you’re a bass lover, Leslie’s with the door up is a nice, though not perfect, place to hear well defined bass. But even with the door up there were other areas left to correct, or calibrate, in the room. Manny was able to improve the highs from the somewhat beamy tweeters on Leslie’s Lawrence Double Bass Speakers by adding a bit of toe in to the speaker positioning. Small tweaks like this can gain you some measureable improvement in how your system sounds, but I if you’d like to fully hear how good your system can sound, you need to measure and adjust for the room interaction digitally. The digital processors that are available today let you bump up the 60Hz dip in your bass, or tame that brightness that comes from a glaring reflection off your windows or the ceiling. Or maybe your speakers’ crossovers were intentionally (or not) designed with a bump or a dip in a frequency that sounds good in one room, but in your home leaves you less than happy? With DSP (digital sound processing) you can fix problems with room interaction and tailor the sound to suit your preferences.

The most common comment I’ve heard when you mention DSP to audiophiles is that they don’t want to introduce another component into their audio gear reproduction chain. And if they’re analog people, like me, they’ll add that they especially don’t want to digitize their music before reproducing it. I will admit that in the past I too have said these things. But as I stated in the first paragraph, I’m a believer in the potential detrimental effects of the room, and I am now a believer in the ability of DSP to mitigate those detrimental effects. The proof, as they say, is in the listening.

Manny started out the event by fielding a variety of questions from those in attendance before we even listened to any music, modified or unmodified. And there were lots of questions! Everyone seemed well prepared to question the validity of modifying the purity of their sound reproduction in order to get “better sound.” Manny’s view on this is that the sound is already modified by its interaction with your room dynamics, and that any possible sound degrading effect (which he doesn’t believe in anyway) from digitizing the source is much less of a detriment than that which comes from the speakers’ interaction with the room before it reaches your ears.      

After putting BSS Audio’s Omnidrive professional DSP unit into Leslie’s playback set up, SFAS members were played a variety of tracks with DSP calibration and no calibration. Instantaneous switching between DSP correction and no correction was made with a custom made A/B box.

The amount of difference you heard depended upon the track being played. For me, some small portions of the live recordings actually sounded better without correction as I felt they were recorded “too hot” to begin with and the correction allowed this irritation in the music to be more pronounced. In the future we’ve decided doing these demonstrations with music that people are more familiar with would be of greater benefit than introducing new unknown variables into the mix. I was familiar with the tracks played, so that I knew that what sounded better in spots without the correction in place was actually an elimination of fidelity in a particular frequency.  But overall, I thought there was far and away an improved clarity that was obtained with the correction in place. 

For those who were unsure about how putting the signal through a DSP unit changed the sound even without correction, at the end of the day Manny played tracks and let people switch between running the signal through the DSP unit- no correction applied- and just listening to the signal passed through the AB box. Some thought they could perceive a difference, some could not tell a difference, but the results of audience members correctly “detecting” a difference, or incorrectly identifying a change was 50%, or no better than random guessing. Manny admitted that for this test to be completely valid it needed to be done with an A/B/X style test, but there was not time for that. The bottom line was that the differences, if any, when inserting digital processing with no room correction, were subtle, if there were any at all, and not at all like those heard when the signal was processed to calibrate the sound for the room. That was not subtle, and was always clearly differentiated.

In conclusion, for demonstration purposes, I have to give Manny kudos for trying to correct the sound not only in Leslie’s room, but in the greater outdoors as well.

I have a feeling this was the first time he was presented with a challenge quite like this. I say this not because he wasn’t up to the task, the task was accomplished, but because the significance of the results of the correction were less dramatic than I know them to be in rooms conventionally enclosed within a building.

For example: Albert Dall, the SFAS Director of Amplification Research, came by his directorship title as a result of his perpetual search for the perfect amplifier to increase the bass and overall fidelity on his YG Acoustic speakers. After spending gobs of time and money, he ended his search only after Manny came and inserted a DSP unit in his system to correct his speaker voicing and the room interaction. To quote Albert directly: “Quite simply I can say the result is stunning! In all of the switching of gear, trying to bi-amp, and wondering if different speakers would solve my wish for proper mid-bass, nothing sounded as good as it does now. Not only do I have deep believable bass/mid-bass, but the measuring after the parametric EQ settings were put in place, have shown that the low output ability of my speakers is such that subs are not necessary, and that nothing sounds better with the correction out of my system. The sound is locked in!”

I’ve heard Albert’s system before the insertion of room correction and was amazed that the quality of gear he possessed produced such a tepid listening experience. I was amazed, but ultimately not surprised. As I like to say, the room is king. But now, I think I’ll say, and Albert would agree- DSP wielded in the hands of an expert like Manny can slay the king. Long live DSP and better sound!

Leslie’s gear on the 26th:

AMR 777 Signature DAC, windows gaming computer (i-7, 16GB RAM, SSD) running J-River, Pass Labs XP-30 Pre-amp Prototype Magnetic Conduction Amplifier (circuit designed by Steve Kaiser from B&K), High Fidelity Cables throughout. Lawrence Double Bass Speakers

One thought on “Excellent Coverage of Room Correction Event by David Hicks

  1. @David Hicks,

    Really great writeup! I soooo wish I could have attended since this is a topic that I’ve been doing a lot of thinking and tinkering about over the past few months.

    I’ve put a link in the forum, but since it’s relevant to this topic, I’ll include one here as well to my most recent blog post on this topic:


    Hopefully some of the practical tips that I added near the end of the post are helpful to SFAS members who are interested in trying DRC in their own systems. Cheers!

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San Francisco Audiophile Society

San Francisco Audiophile Society