Fine Tunes #45
This month's first tweak fits the Fine Tunes bill perfectly, and is aimed at owners of MartinLogan or other electrostatic speakers, with a tip applicable to moving-coil speakers as well.
Mark Gdovin (firstname.lastname@example.org), a regular contributor to the "Soapbox" debates on www.stereophile.com, is crazy about the inexpensive back-wall treatment he's cooked up for his dipole MartinLogan Aeriuses. His tweak is "so killer that you're going to laugh your butt off 'cause it's so simple, but so effective it's sick."
Remember, like all dipoles, electrostatics throw sound to the rear as well as to the front—you must concern oneself with the backwave and its reflection. Mark likes the effect, but, quoth he, "The rear wave must be tamed!" Rather Shakespearian, I'd say! The way to do it, he hotly continued, is to diffract the rear wave. In fact, "It needs the living crap diffracted out of it."
He tried bookcases behind the speakers, but that didn't work out—too hard to find enough books. "A pain in the butt," said Mark. Instead, he recommends two 6' 6" slatted closet doors, hinged in the middle. They're easy to paint to match the décor of any room, and once they're finished, you can place them against the wall behind your MartinLogans, the doors folded at the hinge at an angle of about 30 degrees, their outside edges against the wall, the hinged join pointing toward the listening chair.
"Brother," said Mark, "for the almost $100 this cost, it brings tears to my eyes." He explained that part of the rearward acoustic energy reflects toward the center of the room and part toward the sides because of the doors' positions, and if the doors are sloped back form vertical, part of the acoustic energy travels up.
This type of homemade device can also be useful in directing the reflections lapping around behind moving-coil speakers. I've tried something very similar myself, and, behind his ML Prodigys, www.stereophile.com webmaster Jon Iverson uses blinds carefully slanted up at his 11' ceiling. That really cleans up the midrange, says JI.
Another cheap trick—especially applicable for moving-coil speakers—is one I picked up from the Shun Mook monks and mentioned way back in the September 1998 "Fine Tunes": stuff various sizes of cardboard boxes with varying amounts of newspapers or magazines. Stack them across the rear wall and in the corners behind the speakers to absorb whatever boom may be present.
I just love this next tweak, sent in by reader Charles Roddy (email@example.com). This worthy dude used Purolater II furnace air filters in his system. Placed on the wall behind his speakers, these nice, narrow 20" by 25" by 1" rectangular shapes perform diffracting and damping duties. They come in blue or white (I'll get more information on where they can be found), and are made with a firm cardboard edge so you can easily cover 'em with cloth. Charles discovered that four filters behind each speaker did the trick for him. He has plaster-and-lath walls—a stickpin in each corner and that was it!
[ruffle ruffle] Even if it isn't perfectly effective, the next tweak is cute enough to be included here just 'cause it's so goodhearted and most probably works. Want to improve the sound in the listening room? Just get rid of all those "rattling, reflective, glary-sounding CDs in jewel cases," said Peter Roberts (firstname.lastname@example.org), and replace 'em with a like number of LPs in cardboard and paper sleeves. Of course. This kind of guy I could get along with.
And now, from Tweaker Extraordinaire Victor Tiscareno of AudioPrism/Red Rose Music, who has backed his many tweaks with engineering prowess: "I may have the cheapest tweak of them all for the turntable jockeys out there in audiophileland," he crowed (Victor rarely does). He admitted that the idea was originally lifted from a $50 Vinyl Survival Kit he saw at CES. Some folks, he pointed out, have used heat-shrink tubing to eliminate resonances in a turntable's tonearm. But if you use Saran Wrap...ah-ha! [Ding!] The cost takes a tumble off the cliff! And, guesses Victor, the thickness of the wrap hardly matters.
But Caution! If at all possible, deploy your stylus guard during this operation. If you lunch that cantilever with Saran Wrap, I'll change the access codes of the "Fine Tunes" Secret Decoder Ring! Seriously—do this only if you feel competent and your extremities don't shake. If you Saran-Wrap that cartridge to kingdom come, I take no responsibility.
Once you've signed the Official Secrets Act, cut a strip of shrinkwrap about 12" by 1½" with a knife—that is, if they let you mess around with sharp objects where you are. Assuming you use the standard-mil materials, the wrap will add very little mass to the tube and will probably not even require, Victor supposes, changing the stylus pressure. Although some among us will insist on doing so, of course. Bless 'em. "And it works!!!" That's Victor, crowing again.
Intimacy with your system. It's a fine thing.