A Special Report On Room Acoustics At Tradeshows - by Richard Bird
After a summer break, it's back to acoustics. I had intended to write on DIY and some basic room setup tips. However, that's going to wait until next month. I just returned from the Denver Audio Fest. This was a really great show in my opinion. It was not crowded as it was the first year and you could go into the rooms and listen to your heart's content. Most of the rooms were 2-channel. There were many high-efficiency, low-power SET rooms, typically with horns. But, there was a nice display of solid state and more mainstream loudspeakers as well. In other words, it wasn't a glass show but rather, a very broad and refreshing mix.


So why would I write on acoustics about this show? We all know that hotel room acoustics are terrible, right? Well, for the most part they are. The floor-to-ceiling array is typically poured concrete and the walls are relatively flimsy and weak. Placement options can be limited and bringing in a truckload of acoustical treatment is less than practical. However, I learned some things at this show I want to report on because I think it really bears on the fact that different speakers interact differently in different rooms. The other aspect is that these exhibitors have to deal with an unknown room with mere hours, not days to set up and battle whatever acoustics await them to get the sound to at least decent quality for their potential customers. When I visited these rooms, I had no idea I would write this article or I would have photographed all of them to show exactly what they did. Fortunately, 6moons was kind enough to send us some of their photographs for documentation.


Let's start with Cain & Cain and the most incredible looking tube amps by Josh Stippich. This room was almost square, not a fortuitous beginning. But the exhibitor compensated for that with an asymmetrical placement where the distance of each speaker -- to the back wall and sidewall -- was different for all four measurements. This meant that the ¼ wave length cancellations were different and the normal peak/null distribution of a square room was greatly disrupted. This room used no acoustical treatment. The reflections off the back wall were somewhat bothersome but the apparently high directivity and off-axis placement made the side wall reflections bearable - they could be heard but were not as objectionable as many other speaker setups I heard. Most listening sessions in this room on the ground floor left the door open to release the build-up of bass energy. Did they accomplish their goal? Well, that depends. They did dramatically reduce bass peaks with their placement for a room of such -- acoustically unlucky -- dimensions. They still suffered resonance modes that were clearly heard but not nearly as bothersome as I would have expected for a nearly square room. Overall, I would have to say: "Bravo!" Next time, just a little bit of acoustical absorption on the rear wall and perhaps some on the sides and it will be really great sound. DeHavilland [below] used a similar asymmetrical/diagonal setup but their room was not as close to square as the Cain & Cain room.


Now, there were a few rooms set up in the usual conventional fashion. Two in particular were organized by the same dealer and they were both large rooms, practically identical in size and shape. Both used ASC products in a similar fashion. Both had very high-end amplification and front ends. However, the speakers were very different. This was a case where the more expensive speaker with its full strong bass was quickly clouding the midrange and the less expensive speaker delivered clarity, speed and detail that far surpassed its more expensive competitor. Was the less expensive speaker better? Perhaps - but more importantly, the less expensive speaker was better suited for its venue. To me, this was a clear demonstration of needing to balance the room to one's speaker selection. You don't want to put the humongous behemoths of the universe in a 10' x 12' room. By the same token, don't hope to rock on a pair of small 2- way monitors in a 20' x 30' room. Select your speakers and room accordingly. They work in tandem so you have to select them to work together well.


Another room that was very unusual in terms of acoustics was by retailer Listen Up of Denver. This room showcased the Sonus Faber speakers and Musical Fidelity electronics against a long window wall in two separate systems. To the left was a pair of monitors, to the right the flagship Stradivarius which I had not heard before so I definitely wanted to take a listen. Now keep in mind that there was a wall to the right of them and a lot of open space to their left where the other system was set up. This array appeared as though someone in sales (who might not have been the sharpest tool in the shed when it comes to setup) said: "The customers need to see both systems. The more expensive one should be most visible but both should have equal space and equal layout." Then it seemed as though they just plopped the speakers and rack down where they looked good. There was no acoustical treatment -- unless you count the drapes on the wall behind the speakers -- but nothing on the side walls. So the obvious conclusion would have been one of a terrible left/ right imbalance. Well, I probably wouldn't mention this room if that had been the case. I was really shocked by a few things. One, the speakers were very musical and really drew me into the sound. What was really amazing? They sounded perfectly balanced as though in a perfectly symmetrical environment. One day I want to measure these speakers myself. My subjective impressions would have me believe that the off-axis response falls off dramatically. However, most speakers with this presumed quality do not image once you get just a hair out of the sweet spot - and these performed very well even when you sat a foot to the left (the right did exhibit slightly more loading on the midbass). So, either these folks got incredibly lucky on the setup or, more likely, someone was very familiar with the speakers and how they would perform in this environment and set them up accordingly. This was an example of the benefits of working with a full-service dealer who is knowledgeable about equipment setup.


A few other rooms did pay some attention to acoustical treatment. ESP is back in business if you didn't know and from what I heard particularly with the smaller set of speakers, they are going to enjoy some very good acclaim. One thing to note about ESP speakers is that they use two tweeters. One is side-firing and 10dB down. In the room with the smaller speakers, they had used several professional acoustic treatment items but the blankets on the walls to reduce first reflections (somewhat difficult to see in the photo), back-wall reflections and to tame the side-firing tweeter a bit worked quite well. They still had a bass issue but that was the typical room mode problem and I'm fairly certain that in a more acoustically friendly environment, the bottom end performance would have been quite good.


Lastly, there was one group of exhibitors that really impressed me in terms of ingenuity to get good sound at the lowest possible cost. I always like people who can achieve this and feel there should be a show award for this. This room of the Dowdy Lama & Friends had very efficient and rather large horns for the size of the room. I'm quite certain they could have overloaded the room in no time. Instead, what did these folks do to deal with their acoustic dilemma? They brought in no less than 7 mattresses from the hotel to absorb and damp the room. Most of these you can't see from the photograph as they were in the back half of the room (but one is just visible in the right picture between the speaker and the VRS stand - Ed.). The hotel was probably happy because they were desperately trying to figure out where to store all the mattresses that were removed from all exhibit rooms. Heck, if these guys were smart, they even got the hotel to give them a discount for storing their mattresses for them.

What I didn't see? I didn't see any RPG vari-screen products. This is regularly used for temporary show venues. It is absorptive on one side and diffusive on the other. It is the most flexible show-related acoustical treatment product on the market. However, it's very expensive and very heavy, adding more expense to shipping and setup. So while the reasons I didn't see any vari-screens are not surprising, it still seems to me that anyone setting up a sound room for a consumer or industry trade event needs to have an acoustical agenda - a specific game plan on how to deal with the potentially terrible acoustics of a hotel room and particularly in a show like this which nobody had attended before. In my mind, the vari-screen is a clear and flexible choice to solve multiple problems at once. But the mattress plan really got my attention as the most cost-effective and convenient way of dealing with the issue. I wonder how many mattresses we will see at the next show?

I also want to thank Ron Welborne of Welborne Labs for being just naive enough to run a show like this. He had no idea about the work involved and I know he worked hard because the show rolled out beautifully. I hope it will return next year. Ron had also invited me to speak at the conference where I gave 3 separate lectures on acoustics and one panel discussion with Steve Hoffman and Robert Harley. I was pleased that the room was standing-room only but even more pleased that Ron had the forethought to have lectures on acoustics at this show.

Note: I heard many good speakers and systems at this show. Most are not mentioned just because this article was focused on what people did with regard to acoustics and setup.

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