Hard though it is to believe, it is now twenty years since the first units for the digital correction of speakers in rooms began to appear. I recall that when I first wrote about the Sigtech for TAS in 1992, I called up TAS headquarters, then in Sea Cliff, and described to one of the TAS staffers (not HP, but someone who is also still around) what the Sigtech did. I shall never forget his response: “If this thing works, there will be nothing left to review.”
DSP did and does offer revolutionary power to control what one hears, though some things, speaker radiation pattern for example, are beyond its control. There are still things to review. But the Sigtech did work so remarkably well that I expected an immediate and profound impact of DSP on audio. But for various reasons, the DSP revolution moved into audio somewhat more slowly than it ought to have, considering what it had to offer. One reason as far as the Sigtech was concerned was that it was really expensive and also not all that easy to program. It was basically a professional product and the consumer had to have faith and patience to get to the startlingly good results that DSP, as embodied in the Sigtech, could offer.
But in the digital world, twenty years is a very long time indeed. And now, twenty years after my first Sigtech review, I have in hand the DSPeaker Anti-Mode 2.0 DualCore. It is reasonable in price ($1199) and simple to operate, and it offers an abundance of DSP features of great effectiveness and the highest sonic quality, including top-quality digital-to-analog conversion included in the package. The DSPeaker Anti-Mode 2.0 DualCore (just DualCore hereafter) does what it does superbly well, and it is so affordable that adding it to almost any serious audio system is financially reasonable as well as sonically beneficial in a big way. It should be irresistible to anyone who does not already have a DSP room-correction device— or even to those who do have one already, because this one is new and different. And it can vastly improve the sound of almost any audio system.
The DualCore is a digital signal-processing device. While it can be used as a straight DAC, with TosLink and USB inputs and analog outputs, it is really intended to operate on its input signals and do things to them, to make your audio results better. What it does to them is various kinds of alteration of their frequency response, i.e., equalization. It does not alter phase independently of amplitude response, although that is possible in digital signal processing (hereafter DSP). It does what is called minimum phase equalization, where the phase behavior is determined by the amplitude behavior in a particular way that mimics what most physical processes do.
The DualCore can be used in several different ways. First, it can be inserted in the tape loop of an analog preamp, with analog in and analog out, like a classical analog EQ device. In this use, the analog input is converted into high-resolution digital, processed (EQed), and then converted back into analog. Some audiophiles will be immediately worried but really they should not be: Highresolution digital A-to-D-to-A is an essentially transparent process.
Alternatively, one can give the DualCore a digital input as described above, let it convert the digits after processing into analog (which it does very well), and feed the analog output into a line-level preamp. Or one can feed the analog output directly into an amplifier: The DualCore has a volume control and can thus function as a digital preamp. The DualCore also has two analog outputs—RCA and XLR—that can drive a subwoofer system as well as the amplifier for the main speakers if desired. (More later on its use with subwoofered systems.)
Connection is straightforward and clearly explained in the manual. All you might need is a TosLink cable for your CD connection, if you do not have one. Easy to get and cheap.
The DualCore has a small but clear built-in screen that shows menus of the operations available and the results of measurements. The navigation of the menus and the choice of operations are done using a small remote control.
What the DualCore Does: Basic Bass Correction
The heart of the DualCore’s operation is a bass room-correction system. The upper limit of the frequency range corrected is user-selectable, from 80Hz up to 500Hz. The default setting is 150Hz. Why bass correction only? Because the lower frequencies are where the room has the largest effects and the largest errors consequently occur. If you have good speakers, you are already hearing something like correct response from around 500Hz on up because in that range the direct arrival from the speaker dominates what you hear. Lower down, the room has huge and audible effects that need fixing. This is almost inevitable. It is a piece of really good luck if the bass in a given room turns out perfectly. This hardly ever happens, no matter how carefully one places speakers and in how good a room. Look at the measured room responses published round and about. Almost none of them are flawless. Bass needs fixing in almost all cases. (You can see a lot of examples in my general articles on digital room correction on www.regonaudio.com.)
Of course, the domination of the direct sound above 500Hz is not total and also even the best speakers can usually use a bit of tweaking. What you can do with the DualCore above 500Hz I shall get back to in a minute.