a. Correct (i.e., smooth, and possibly reshape) the system’s frequency response curve at the listening position. This may involve separate correction curves for each
b. Compensate for timing/phase response anomalies in the system.
c. Correct for room acoustics problems, anomalies.
d. Help automate system set-up.
e. Help integrate subwoofers, if any.
f. Possibility of combining all of the above in a DSP-controlled electronic crossover system.
2. General Concepts
a. Near-field measurements (characterize the speaker independent of the room).
b. Resonant-field measurements (characterize system performance within the room, taking room acoustics into account).
c. Measurement signals are digitized, allowing us to compare actual response characteristics vs. ideal response characteristics.
d. Algorithms plot correction curves that, if applied in real-time by powerful DSP devices, should theoretically cause actual performance to match (or nearly match) ideal performance goals.
3. The Art of the Game
a. Good measurement tools.
b. Sophisticated algorithms (and acoustic models).
c. Adequate processing power.
d. Knowing when “less is more.”
e. Knowing when not to be held captive to your own idea (thinking outside the box).
f. Good ears and careful listening.
1. Home Theater Solutions
a. Anthem: ARC
b. Denon: Audyssey
c. Harman-Kardon: EZ-Set EQ
d. Integra: Audyssey
e. Lexicon: V4 EQ
f. Marantz: Audyssey
g. McIntosh: Room Knowledge (a Lyngdorf-licensed product)
h. NAD: Audyssey
i. Onkyo: Audyssey
j. Pioneer: Advanced MCACC
k. Sherwood: Trinov
l. Sony: DCAC
m. Yamaha: YPAO
2. High End Audio (and Pro Audio) Solutions (red denotes discontinued products)
a. Accuphase (DG-28 Digital Voicing Equalizer)
c. Behringer (Ultracurve Pro DEQ2496 Digital Equalizer)
d. DEQX (HDP-3 Preamp Processor, PDC-2.6 Processor, PDC-2.6p Preamp Processor)
e. DSPeaker (loudspeaker, bass-only equalizer)
f. Holm Acoustics (DSPre 1 Preamp Processor, and DSPreLab)
g. Lyngdorf (TDAI RoomPerfect Digital Amplifier, DP1 Digital Preamplifier, RP-1 Digital Processor)
h. Perpetual Technologies (P-1A Processor and SCOS Speaker Correction Only Software)
i. Sig Tech (AEC 1000 “Digital Time Domain Room & Speaker Equalizer”)
j. TacT (RCS 2.2 Stereo Digital Preamplifier)
k. Z-Systems (RDP-1 digital preamp)
1. From the high-end perspective, is DSP a gimmick that causes more problems than it solves?
a. While this might once have been true, two factors are making the situation more promising than ever for audiophiles.
i. First, algorithms are becoming more sophisticated over time, as is our understanding of the importance of “target curves.”
ii. Second, DSP engines are getting much faster, more powerful, and cheaper over time, meaning we have (and can afford) the horsepower we need—even for very complex algorithms.
2. Doesn’t DSP impose some level of “processing haze” that mars transparency?
a. Possibly so, though the answer depends in part on the absolute resolving power of your system. In the end, though, the question always distills down to this: do the benefits of DSP outweigh any drawbacks there may be?
i. Example: ultra high-end audiophile Atul Kanagat, now with Harman International, heard my demonstration of the Audyssey system used in conjunction with the PSB Synchrony speakers and unequivocally felt that the system increased the overall clarity and transparency of the sound.
ii. Example: TAS Editor Robert Harley has reported using the Audyssey system with his Wilson reference speakers with good results.
iii. Example: TAS Senior Writer Dr. Robert E. Greene has written numerous articles describing “net positive” results achieved with various DSP systems.
iv. Example: TAS Senior Writer Alan Tafel has commented favorably on the Wisdom Audio speaker system, which uses a DSP-controlled electronic crossover/room EQ system.
3. Isn’t the case that DSP is fine for home theater, but not really good enough for use in serious high-end systems?
a. It is true that DSP systems have thus far gotten their strongest footholds in the home theater world, though that isn’t too surprising given the potential sales volumes involved. But that doesn’t mean DSP has no legitimate role in the high-end. In fact the opposite may be true.