Note: In the course of receiving GIK traps to replace those "borrowed" from my main system for bedroom-system tests, I'm taking the opportunity to broaden trap coverage to test the extent, if any, to which additional traps affect perceived performance. What follows is an excerpt from an email sent this afternoon to some interested friends who've been following my "journey". As indicated, I'll supplement the test of scatter-plate 244's at the second reflection points with one using the full-range 244's due on my doorstep this coming Monday:
The pair of 24”W x 48”L GIK scatter-plate acoustic panels intended to replace those “stolen” from the main system arrived on schedule yesterday. As I indicated in an earlier email, I wouldn’t remove the “stolen” ones immediately from their rear-corner positions, but would place the new ones temporarily at the second-reflection point positions on the bedroom side walls to test their effect on the sonic presentation. The positioning looks like this and puts the new traps slightly ahead of the plane of my ears:
I took the setup for a listening spin after closing the window curtains. Glass panes are notorious reflection generators and have the added liability of “sucking out” bass as they vibrate upon being struck by low-frequency sonic energy. (That’s why I don’t advise glass doors—or, for that matter, shelves--on equipment, record, or CD cabinets—they degrade sonic performance in so many ways.)
To begin the listening session I took the unusual step of using three YouTube music videos as the source. “Unusual” because YouTube audio is nowhere near reference quality. But in this instance I wanted to determine what, if any, impact the addition of second-reflection traps would have on three French horn solo performances suggested to me by a friend. Each was a live performance in what I would consider an average listening venue. And the French horn is both unique in its sonorities and an instrument that “energizes” the space around it in ways whose presence or absence is easily discernible with audio equipment of reasonable quality.
I tested twice for each selection—once with the new traps absent, and then with them installed at the second-reflection points. Considering the YouTube source, the French horn sounded pretty good without the new traps. But it was a whole new ball game for each selection with the new traps in place. For one thing, the performance venue “expanded”, most notably in its delineation of interior space. That was important, because the horn now had more perceived room to “breathe”. Breathe it did, filling the space with a palpably plangent presence you hear when you’re up close and personal with brass instruments. And on YouTube, no less.
I then moved on to my usual listening-evaluation suspects [all either CD rips or high-resolution downloads (24/96 to 24/192 PCM or DSD64 to DSD128)], most of them large-ensemble instrumental or choral works, using the same with-followed-by-without-the-new-traps scheme. A few are works I’ve mentioned here recently, including by Morton Gould, E.J. Moeran, Jerome Moross, and Gustav Mahler. Each traps-in-place audition blew me away with enough contrast between trap changes to rule out confirmation bias as an explanation of perceived differences.
I’d note here that even when the room was not trapped at all, I could discern depth to some degree in performances where the recording engineers got it “right”. (That’s in large part due to pulling the speakers out from the front wall as far as foot traffic into and out of the bedroom would allow. It’s too bad I can’t pull them out farther. And that ain’t going to happen.) Progressively trapping the room, starting with the front wall, then the back, and then the first-reflection points made the front wall behind the speakers “disappear” to an increasingly greater degree. And once I’d trapped the first-reflection points the layering of instrumental or vocal rows perceptible on the recorded soundstage was more than decent. But treating the second-reflection points presents a whole new ball game in rendering the performing instruments (including voice) as palpable entities, tonally and timbrally as well as “visually”. There’s more natural decay (and “roll through the floor”) of bass drum and tympani strikes (and with that, a greater sense of “real” low and mid-bass), more resonance to strings—low to high—and, yeah, an even more acute perception of triangle and celesta nuance that I thought had disappeared with excessive ear mileage.
Caution has to be applied in a situation like this. Even though they're "passive", are the new traps applying a sonic signature of their own to what I’m hearing in the same manner that source and amplifying electronics as well as speakers tend to “color” their output depending on how they’ve been designed and voiced? I don’t think so. With all the improvements I hear, the pinched acoustic of Philadelphia’s Academy of Music doesn’t mimic the broader ambience of Manhattan Center; nor does the latter ape the marvelous space that’s Amsterdam’s Concertgebouw. Each venue is more spacious and clearly defined, to be sure, with the new setup. But there’s no mistaking one for the other in what I’m hearing.
Nonetheless, I’m open to more testing. And I should get it beginning on Monday, when FedEx tracking says a “replacement” pair of full-range-absorber 244 traps (so-model-named because they’re two feet wide by four feet long by four inches deep insulation-wise) will show up on my doorstep. Before I do any “replacing”, I’ll swap them out with the new scatter-plated traps to see what difference removing that scattering/diffusing feature at the second-reflection point does.