two XdS satellites and two XdW powered bipole subwoofers. The XdA’s equalization and filter parameters are held in nonvolatile mem- ory, and can be updated via a USB link using a Windows XP program (provided you have Microsoft’s
.NET extension installed).
The three filters NHT sent me were:
1)“flatterhighend.flt”—similar to the original filter set, but, according to Jay Doherty’s enclosed notes, “Flat- ter above 10kHz; crossover point between tweeter and midwoofer moved up a hair (to 2.4kHz from 2.3kHz) to increase power handling; reversed sub phase to try for better sub/satellite integration”;
2)“150Hzcrossover.flt”—intended for dual subwoofer use; keeps the inverted subwoofer phase but moves the crossover between the satellite and subs from 110Hz to 150Hz to enable the system to play louder; and
3)“150Hzxovereqto20Hz.flt”— equalizes the subwoofers to be –3dB at 20Hz instead of 26Hz.
There will be more filters to come. According to Doherty, “We are working on a linear-phase filter to use between the satellite and sub- woofer. LP filters require firmware changes that we should be able to implement by the time the first room EQ software package is com- plete. However, this will increase total system processing time to about 18ms (from 7ms), so it might not be usable with video.”
Kal had used only a single XdW subwoofer, but as I intended to try the filter sets with the higher cross- over frequency, I asked NHT to send me a second subwoofer. This increas- es the system price to $7200.
Sound: As KR had described, set- ting up the Xd system was quick and easy. Unlike Kal, I had no ground- loop problems, but this may have been due to the fact that I used bal- anced connections.
Preamp was first the Mark Levin- son No.326S, connected to the NHT XdA power amplifier with 15' runs of Madrigal interconnects; then an NHT Passive Volume Control, connected with 6' runs of Canare interconnects (the only balanced cables I had with the necessary TRS connectors). Digital source was either a Mark Levinson No.31.5 CD transport or a Technics DVD-A10
F O L L O W- U P
DVD player, hooked up to my ML No.30.6 D/A processor via Kimber Kable Orchid AES/EBU or Audio- Quest SVD-4 S/PDIF datalinks, respectively. The No.30.6 was connected to the preamp with balanced 1m lengths of AudioQuest Cheetah. I also used an Olive Symphony media server to play back uncom- pressed 16-bit AIF files via a TosLink connection to the Levinson DAC, and an Ayre C-5xe universal player connected to the preamps with 15' lengths of balanced Crystal intercon- nects.
When he’d first set up the Xd, Kal had remarked on a lack of integration between the satellites and sub- woofer: “I measured an in-room response that dipped several dB in the upper-bass range centered on 130Hz. This detracted from the general impression of weight, warmth, and richness of sound. While the crossover slope between the XdS and XdW may be a very steep 48dB/octave at 110Hz, there is still significant signal overlap between the woofer and satellites; the positioning of the woofer is important. A lower frequency, of course, would compromise the power-handling limits of the XdS’s 5.25" driver. I found that moving the XdW forward so that it was the same distance from the listener as the satellites filled in the integrated response, as confirmed by instrument and ear.”
With first one subwoofer, then two, and using the same filter set Kal had used, I couldn’t eliminate the upper-bass discontinuity no matter how I experimented with subwoofer positioning. The bass region was rich and deep, but didn’t integrate sufficiently well with the satellites. In addition, while midrange tonalities were reproduced with a delightful lack of coloration, there was a somewhat reticent quality to the highest frequencies. Whether or not these problems bothered me was very dependent on the music played.
I have written before about how the choice of playback equipment can change the choice of music played. The discontinuity between the satellites and subwoofers was more audible with rock music, with its ubiquitous four-in-the-bar kick drum, than it was with classical recordings. For the three weeks I used the Xd system with the original
crossover filters, I found myself playing a lot more symphonies and concertos than I had done with other speakers that have recently occupied my listening room.
The Xd’s extended low frequencies were a much-appreciated benefit with this kind of music, and the sys- tem’s somewhat veiled highs were much less of an impediment to musical enjoyment. I dug out discs that I hadn’t played much, such as Michael Tilson Thomas’ reading of Mahler’s Symphony 3 (SACD, San Francisco Symphony 821936-0003-2) and Seiji Ozawa’s of Tchaikovsky’s Symphony 6 (SACD, Pentatone PTC 5186 107). The double basses in the former’s final movement had glorious weight through the Xd system, though I found the system’s midrange resolution very revealing of the wayward intonation of the occasional sustained brass chord in the latter. But when I played Eric Johnson’s “Desert Rose,” from Live from Austin TX (CD, New West NW6084, recorded for the Austin City Limits TV program), the low bass just grumbled along with the higher frequencies.
There was also something I noticed with the toneburst track on my Editor’s Choice compilation (CD, Stereophile STPH016-2). This track comprises equal-length tonebursts that move from 32Hz up to 3.2kHz in half steps, then back down again. I created this signal to investigate room and speaker-cabinet resonant problems, but when I played it over the Xd system, I was puzzled to hear
what sounded like very faint “ghosts” accompanying the sinewave bursts, almost but not entirely like modulation noise. A puzzle, though I did wonder if this phenomenon had something to do with the veiling I had noticed on music.
Time to install the new filter set. I began with “flatterhighend.flt,” but
thenchangedto “150Hzcrossover.flt” because the system was still having difficulty handling music with extreme amounts of upper-bass energy. Stanley Clarke’s double-bass solo on Airto Moreira’s “Nevermind,” from our Test CD 3 (Stereophile STPH006-2), managed to shut down the left-channel satellite-woofer amplifier at the volume I was finding appropriate for the music. (The image lurched to the right and a red light came illuminat-
