The Acid Test
“I’m not sure certification is absolutely necessary,” says Greene, “but if you’re going to go to all that trouble to build it, you might as well go all the way.”
Designer Dan Zellman spent a good day checking out the room, and gave it excellent marks. “He checks the sound coming from the speakers, the acoustical coupling with the room, the anechoic ‘hole’ following the initial blast, then the first reflection and the diffusion.”
“Obviously you can’t get rid of all of the uncontrolled sound, but the concept is valid as long as it’s within certain specs, which are pretty stringent,” says Greene.
In spite of the good evaluation, Greene noticed there were problems with the finished room. “It was a little short on the low-end. The kick drum wasn’t reaching out well.”
“On a hunch, I removed the drivers from the UREI 813A’s we had put in, and replaced them with our old Altec 604-8G’s. Even though they were out of time-sync, it cleared up the problem immediately.
“I was actually pretty upset. I had ordered 813’s, which use essentially the same drivers as our old Altecs, but by the time we took delivery, UREI had stopped shipping them and sent us 813A’s instead. The difference is that the new speakers use ceramic magnets.”
“They’re always talking about how great they are, but the real reason is that AlNiCo, which they used to use, got too expensive.”
“But the ceramic magnets have poor low-end response, and they sound harsh and strident. The speakers measure out the same, but they sound totally different.”
“I had to take the horns off the Altecs and put the little blue UREI horns on them, and I had to buy different crossovers, because the ceramic magnets are shorter, and therefore use a shorter delay. Now they sound great. They’re about 2 dB less efficient, but I can deal with that.*”
As one might expect, Greene is very happy with his new room, and knows why. “It doesn’t wear me out nearly as much — I can work for a long time now,” he offers.
“Since the speakers and the room are all phase coherent, I don’t have to listen to phase distortion, which is very fatiguing. I’m also working 7 or 8 dB softer. I can hear things more clearly at lower levels, which also helps to make it sound better on the street.
“I realized that the other room tended to ‘smear’ the image, which had to do with reflections off the ceiling. It was tough to hear small panpot adjustments.”
“Also, now that I have the new speakers, the room sounds pretty much the same over a wide range of seating positions. Of course, you’re limited by the on-axis response of the tweeters, but I think the room even compensates for that a little.”
“I always tend to listen on headphones before 1 let anything out, and LEDE and cans aren’t really too far away from each other. You can’t really get a good idea of bass on phones, however, and there’s no ambience. So this is the best of headphone-type listening, yet without the drawbacks.”
The new room has changed some of Greene’s work habits. “Things that sound really bad will drive you out of your mind, he concedes. “For example, piano miking that used to sound fine now sounds as if the piano is inside out. You become hyper-aware of phase anomalies.”
“I find that I’m using a lot more coincident-mike placements, and paying a lot more attention to phase coherency. I’m also taking more care with mid-range EC). I can hear the subtleties better; of course, that has a lot to do with the speakers as well as the room. I’m mixing wetter, and I’m using the wall monitors a little more than I used to.”
“The room makes very little difference when you’re near-field monitoring — the primary reflection there is still off the console itself — but I never liked small console speakers anyway. They’re only really effective in the mid- range, and I have three different sets that sound completely different.”
The new room has also necessitated changes in monitor amplification. Because of the reduced efficiency, the old Spectro Acoustics 125 watt per channel power amps were replaced with a Mcintosh Model 2500. An intermediate setup used UREI power amps, but Greene found them short on headroom, and the damping factor to be too high for his speakers.
“The Altec-type woofers are made to move around, and the UREI held the cones too tightly,” he says. “The Mac is transformer-coupled, and although it has a high damping factor for that type of amp, it’s a lot lower than a direct- coupled amp. It’s much nicer to listen to.”