The digital signal processing utilized is a proprietary technology of parent company VLSI, who manufacture their own chip sets – Nnt a capability open to most manufacturers. The product for review here, is the most advanced application of their in-house capability to date and it goes a lot further than sub bass equalization. To give it it’s full title, the DSpeaker Anti-mode 2.0 Dual Core, is an asynchronous reclocking USB digital to analogue converter, with DSP room equalisation. With USB, S/PDIF optical and analogue inputs, plus a volume control, it’s also more than capable as acting as a fully fledged, remote control pre-amp too, but even that lofty list sells the Dual Core’s capabilities a bit short. Get a cuppa, because this digital Swiss Army knife has something of interest for everyone and it’s going to take a while to explain it!
Design and Connections
Any constrained volume of air resonates and does so at a frequency that is a function of it’s volume, pressure and dimensions. As we can assume pressure to be constant and the volume to be as a result of the dimensions, it the dimensions that we, as audio buffs, need to concern ourselves with. As with an organ pipe, a longer tube resonates deeply, with shorter tubes resonating at a higher frequency. Fine, but we don’t live in tubes do we? No, it’s worse than that, because if we did, we’d only have to worry about the first, deepest resonance (the fundamental resonance) and then the multiples of that frequency (the harmonic resonances) all of which relate to that single dimension. In the real world, our rooms have three differing measurements of length, width and height, each of which supports resonances relating directly to their dimensions.
If you have a four metre wide room, that equates to a room mode centred on 50Hz, with harmonics at 100Hz, 150hz, etc, ad infinitum with reducing intensity. But if you move along that four metre dimension, you will alternately hear areas were the tone is massively loud (a modal peak), virtually absent (a modal cancellation) and about right. There are plenty of simplified on line calculators, to help you even visualize where these peaks and dips may be. Now let us assume that the room is eight metres long too. You potentially have peaks and cancellations at 25Hz, 50Hz, 75Hz, 100Hz, some of which you will note, interact with the width related modes. They could add additional boost to a peak, or impose a cancellation upon that peak resulting in a normal level of sound. Now add in the floor to ceiling dimension, the fact sounds also reflect from walls in oblique and tangential modes (we were only looking at the simplest, strongest axial modes) and it gets very tricky to predict a reliable picture. But we’re not finished, because in this 3D morass, you, your speakers and sub will all be comparatively random dimensions from each surface, plus the physical construction of the room may mean one surface reflects a given frequency strongly, whilst the opposite absorbs it. At some point, you're supposed to sit in there too and your position is as likely to be dictated by where your sofa can actually go, as opposed to where will give the best sound.
Now, there are three approaches to dealing with this audio hell. One is to ignore it, which is surprisingly popular in the main stream. The other is to tackle it head on with room treatments, such as absorbers and diffraction panels. These tend to be of limited use at bass wavelengths, but very effective at higher frequencies where, paradoxically, electronic equalisation (EQ) is less effective. They also tend to be, even in the most stylish cases, visually rather obvious which may preclude marital bliss, if you achieve it all. So, as far as your bass is concerned and assuming you've done all you can in terms of maximising positional fine tuning, it's likely that the invisible solution of electronic equalisation is likely to be attractive and due to the scale of potential issues that can manifest in the sub bass, also effective.
There are a vast variety of devices now on the market to aid you in this quest. Virtually no home cinema receiver can hold it's head up unless it sports at least some EQ as part of it's automated set up routine. These can vary greatly in quality and apart from a small subset, most I've heard leave a lot to be sonically desired. Fortunately there are plenty of stand alone units capable of bending your bass back into shape and all of the ones I've tested have proved effective. They do however, tend to fall into two camps. The totally automated and the totally manual. With the latter, you can (with practice) tailor your bass to your exact desire, whereas the former will tend to tune everything toward the manufacturers pre-set goal of correct.
The issue is that different rooms respond differently to different levels of bass. My room seems to enjoy a very flat response, but a friend's room, tuned to the same measured response, has you wondering if you've even turned the subwoofers on. It eats bass. One size does not fit all, where sub bass is concerned and that's before you've even allowed for a bit of personal preference. It's about time someone hurried up and made an auto EQ device with some user tunable parametres. Well, now they have and they didn't just stop at that....
Rear connections are maybe a touch limited, given the potential for use as a pre-amp. The stereo balanced XLR and single ended RCA phono connections are in fact the same input, so you have to use either one or the other. That doesn’t mean, connect up both and play one source at a time, that means connect only one set at a time. The handbook is clear on this, although not as to the potential ramifications of ‘having a go’. I chose to believe them and not push my luck. Input sensitivities are quoted as 1.3/2.6V(RMS) for XLR and 1.6/3.25V(RMS) for RCA. The dual voltages on each analogue input as quoted are to allow for differing output levels between hi-fi components. A ‘quiet’ source, will not make use of the full bit depth in analogue to digital conversion, whilst a ‘loud’ source can cause clipping of both the analogue input and analogue to digital convertor, the latter sounding particularly nasty. There are (in the menus) high and low sensitivity settings to aid you, although careful experimentation will be required. Output voltages are fixed at 1.65V(RMS) for RCA and 3.25V for XLR.
There are two digital inputs – Mini USB and an independent optical S/PDIF Toslink connector, both of which are subjected to internal re-clocking, for jitter reduction. The inputs are mirrored with identical outputs, USB excepted. The digital inputs will accept 2.0 signals at 44.1 or 48kHz sample rates and up to 24bit resolution, the digital output mirroring the input. The USB input also doubles up as a connection to your PC, for data transfer to DSpeaker’s free software, more on which later. As the USB input is not mirrored on the front panel, accessibility within your rack may dictate how often you choose to access this feature.
The internal architecture of the Dual Core centers around the VLSI parent company's VS8053 IceDragon chip, which handles analogue in/outputs, ADC/DAC conversion and all DSP processing on one chip. A separate VS1000 handles the GUI and the USB interface. All processing is 40bit with 6.144mHz oversampling on the ADC and DAC. The Antimode Room EQ uses a combination of Finite and Infinte Impulse Response filters, the exact number and implimentation of which, DSpeaker stays tight lipped about. This is, after all, their core technolgy. A point worth noting is that the VS8053 can only handle license free digital codecs, which means WAV (PCM & IMA ADPCM), Flac and Ogg Vorbis.
Source and output switching is independent, meaning you can utilise the digital outputs with an analogue source, digital input to analogue out and of course, analogue in/out or digital in/out. Whilst the digital output always remains at full scale, rather nicely, the Dual Core utilises a digitally addressed analogue volume control for the analogue outputs. The alternative, full digital volume control, works by compressing the digital bit depth of the outgoing signal from the DAC, which essentially looses information. Whilst this method works okay at high outputs, by the time you get down to late night listening levels, the compression sounds horrendous and, indeed it is the Achilles heel of many budget DACs, made with a nod to pre-amp functionality. With the Dual Core, if the number of inputs is sufficient for your needs, you really can manage without a pre-amp.
The front of the Anti-mode, sports but two features of note; A 3.5mm microphone input for the measurement mic and the aforementioned colour display. There is no On/Off/Standby button. This display makes full use of it’s pixels to convey a lot of information, very clearly. Clearly that is, as long as you have the eyes of a hawk, or are sitting under three metres away. With my forty year old peepers sitting four metres away, I can only make out the input, or the volume setting which pops up in use, everything else being displayed as small icons, above or beneath this central information. No matter, because unusually for a component of this ilk, you do not have to hook up a computer or external display to access it’s functionality and this is more important. Everything the Anti-mode Dual Core can do, can be accessed, controlled and the result examined, on this jewel of a screen, in concert with use of the supplied remote control.
The remote itself is a small plastic affair, that doesn't quite carry the sense of solidity, engendered by the Dual Core. It's very small and you will loose it in the sofa at some point. That said, in practice I found that the surface of it was sufficiently tactile that I could feel my way around the 'keys' in the dark (it's not back lit) to access the commonly required functions, like volume and mute. To be fair, with the proliferation of universal programmable remotes, not to mention smart phone apps, the remote is plenty adequate and preferable to the package costing £50 more.
There are two reasons not to be in the room when the test tones run. One, is that they're quite loud, the second being that they are staggeringly long. Each sweep starts low, with one full cycle of each frequency up to the EQ limit - quite different from the fast woops and clicks an AV receiver emits. Each sweep therefore takes about a minute and there's seven of them. The audible interference made by you bolting from the room and (softly) closing a door, is unlikely to have any impact on the accuracy of the results, so go and make a cuppa. The additional Multipoint measurements are mercifully only a single sweep. When finished, the screen presents you with a before and after result. Save the results when prompted, unplug the mic and readjust your subwoofer volume. This last step is likely, as with the room modes tamed, the subjective volume of the subwoofer will be a lot lower.
The workflow for stereo use is broadly similar, except for a few additional concerns. One is that depending upon your view of such things and indeed your system's natural in-room reponse, you may want to adjust how high a frequency you want to EQ to. My personal experience of various EQ implimentations, is that you really don't want to EQ much above the upper bass - 300Hz or so. The reasons are two fold.
For starters, as frequency increases, the individual peaks and dips are so narrow and so many (albeit, lower in scale than the bass), that there's little point in trying. Secondly, these peaks and dips are so localised in physical space, that you literally cannot EQ to give the same result at each ear. This is demonstrated when running the full range test sweep. You suffer the weird sensations of the sweep's intensity moving from ear to ear, as a frequency peaks at one ear and then, as frequency increases, the next peak moves to the locality of your other ear.
The other reason is that I've yet to hear a full range EQ system, that doesn't suck the life, sparkle and vitality out of music when it gets anywhere near the midrange and above. I should note, that this is not quite the same as implimenting one of the manual parametric filters to adjust an overall tonal balance issue, such as pushing the midrange in general, either up or down slightly. That said, I did experiment with trying to sledgehammer the overall frequency range to absolutely flat using every PEQ and tilt control and can confirm, that DSpeaker have given you enough adjustments to completely stuff everything up! At least you can save the base EQ to two presets, allowing you to work on one without rendering the other unlistenable.
There are four presets available from the remote, so can flick between your chosen music and movie settings, or wife in, wife out as I call them. On this point, it's worth noting that DSpeaker have included one feature that will get a hammering by every action flick fan, but is worthy of experimentation for all purposes - a 'House Curve'. This is where, after equalisation, you can choose a frequency below which bass gets progressively boosted to a preset higher level. In the Antimode, this is accomplished by setting a combination of Tilt and Lift. Tilt gives seven preset frequencies to boost below, with Lift defining the seven preset amounts of boost. These forty nine combinations allow you to boost like a nutter from just under 40Hz, provide a gentle lift below 100Hz, or any combination of the above. There is plenty of scope to go from gentle reinforcement, to full on subwoofer destruction. The developing theme here, is that DSpeaker have given you plenty of scope to improve almost every aspect of your system's room integration, or just kill your system outright. Choice is a double edge sword that needs wielding thoughtfully.
Finally, I should remark upon the similary comprehensive High Pass and Low Pass controls, that will suit DIY sub types who lack the controls found on off the shelf subwoofers, plus the low end and high end Tilt controls that can be used to literally do exactly that with your bass and treble in stereo speaker mode. These are really subtle tone controls, that work very well and will be instantly familiar to Quad owners of a certain age!
In Use – Subwoofers
Where subwoofers are concerned, it is easy to verify the effectiveness of a room EQ device, by simply measuring the before and after room responses. There is a direct correlation between the measurements and what you will hear, although as mentioned earlier, experience of your room is required to know if that response will actually sound good. The Antimode promises to deliver a flat response, as would be expected from a competent EQ device, but uniquely gives you the tools to then tailor this base line response, to taste. I can’t second guess your requirements and so will simply stick to commenting on it’s automated effectiveness.
It is very, very effective, but let’s examine the measurements in detail. The top graphs, are the simple 2D plots of amplitude (loudness) against frequency. For your bass to sound tight and tuneful, the measurement should ideally be a flat line, meaning all signals of equal loudness are played with equal loudness. In the before trace, the additional power added to certain frequencies by the room modes (resonances, or room booms if you prefer) are quite clear, as are the nulls (dips) caused by cancellations. If this was someone playing a bass guitar of double bass, then it’s clear that some notes would be massively louder, or altogether absent. This is by no means a bad room either – I’ve seen responses that are much, much worse and believe me, people try to comment subjectively on the bass quality of speakers and subwoofers in rooms just like this and worse.
In the after trace, The Antimode has been allowed to run it’s multiple sweeps at the listening position and I’ve then run an additional four in the area immediately around it – I’ve stuck to using points that are where people can actually sit. There is no point in measuring a point just above the coffee table unless you sit there on a regular basis. It has then used it's algorithms to employ the FIR and IIR filters as it sees fit. The difference is not small. In use, individual notes now retain their proportionality, with a note only being louder if the musician played it that way - you are uncovering the expression they placed in the music. Crucially, with the massively dominant frequencies suppressed, you will actually hear more of the deeper tones that were being masked, so your subwoofer will sound deeper and altogether more profound.
But that's not all. A flat in room repsonse is good, but one that is flat AND short is better. Short? As alluded to, a resonance is when your room starts to ring at certain frequencies. Like a bell or a glass (which is intentionally resonant) the note continues on after the initial stimulous and so does a modal peak in your room's repsonse. The subwoofer might have stopped, but the room hasn't. Your ear is actually quite poor at distinguishing a loud note from a sustained one, especially when it's mixed in with everything else that is going on in a movie soundtrack and music. In either case, additional sustain contributes to a lack of drive to your musical bass and blurs detail in LFE sound effects, to name but two examples. The best EQ devices are designed not only to measure the amplitude of your response, but it's duration and account for both. The 3D graphs (commonly known as waterfalls) below show that the Anti-Mode 2.0 Dual Core is firmly in the camp of the best EQ devices I've come ever across.
For the uninitiated, it will help to know what the waterfall above is and how to read it. In this 2D graph, the single line is simply the power of the response as measured imediately as the sound hits the microphone. In the 3D waterfall, you get another line laid in front of the previous repsonse every twenty milliseconds, until the measurement stops at a predetermined point in time - in this case 300ms, or if you prefer after nearly 1/3 of a second. So, the first line at the back, IS the 2D response above, with each successive line moving forward, the reponse of the room moving forward in time in 20ms slices as the sound fades. What you can see is that the large peaks at the back, correspond to the excess energy stored and released in the room.
Take the 30Hz peak. You can see that not only is it excessive, but it continues way after the 300ms cut off point, loosing energy far more slowly that the frequencies either side. Anything with even a hint of a 30Hz(ish) tone in it, is going to drone and rumble away, making all explosions sound the same, with the frequencies either side masked by this massive output. Horrible. But it's more interesting than that - have a look at 55Hz. On the evidence of the 2D graph alone, you'd be sweating on the massive dip, but in the waterfall, it's long term output is far less drastically reduced, even extending into a peak over time. There certainly isn't a noticeably audible hole when you're listening to music, for instance. If your efforts to EQ out the 2D dip work, you could just be engineering in a boost that isn't needed.
And the 'after' waterfall to the right exemplifies why the Dual Core is so good. It's seen the obvious peak and cut it. It's seen the extended decay of the dip and not chosen to boost. Boosting a dip isn't generally recommended, because you're effectively pouring amplifier power and driver travel into a sonic black hole, but that is a rule of thumb. It can be done in moderation and the Anti-Mode allows it, although you can also set the limit of how much is allowed. If you flick back and forth between the before/after graphs, there is a hint of boost between 20-25Hz to bring the response gently into line. Remember too, that this result is just the result of the entirely PC free, automated EQ of the Anti-Mode. For music in my room, that's job done - walk away.
The icing on this particular self contained cake, is that whilst not 3D, the on screen graphs provided by the Dual Core are pretty damn accurate. Bear in mind that in the picture below, the Anti-Mode result is a sum of five measurments, whereas the REW measurements (which have been scaled to match the Dual Core display) are at the listening position alone. There is a very strong correlation, which is refreshing. At least one, more expensive device offered a (PC displayed) output that was so smoothed, as to be little more than confirmation that something had been done, with no real indication of the absolute success.
As a stand alone EQ device for a subwoofer or subwoofers, the Anti-Mode 2.0 Dual Core is as good as it gets, regardless of price.
In Use - Everything Else
In general, via the single ended phone in/outputs, I felt it made a pretty good fist of the job. It was reasonably transparent, if not the most expressive pre-amp I've come across. It was slightly mechanical in it's presentation, which just made things sound slightly measured, slightly restrained in excitement. Via the balanced inputs and having checked that levels were matched I felt some of the zest returned and the top end had slightly more sparkle. Everything felt just a little bit more solid with rythmn in particular driving tracks along with more purpose. Overall, I'd say it was pretty much par for the course as a budget pre-amp.
Then you bring the EQ into play. Whilst a lot of the above still holds true (I still prefered the balanced in/outputs) the benefits from the upper bass down are nothing short of astounding at any price. Operation is much as per tuning your subs, but you also have the added possibilites with the 'tone' controls, plus the ability to shape the overall response with broad parametric EQ filters. So, anyhting that holds true for suwoofer bass, does so for speaker bass, noting that whilst most people run one sub, everybody runs two speakers. The way the Anti-Mode handles bass is interesting. Essentially the very bottom end is treated as mono, applying filters equally to each speaker. As frequency increases, it progressively shifts to EQing the speakers as discrete entities, as the sounds become more aurally localisable to each speaker. Whereas a 50Hz peak will appear to come from everywhere, a 300Hz peak will be audible from the speaker associated with it. As it happens, the Dual Core gets progressively less aggressive with it's EQ as frequency increases, the localised nature of higher frequency dips and peaks making it pointless.
No matter, because with the work wrought at 250Hz and below, the soundstage literally explodes in scale, pushing it's way through your rear wall, the speakers seemingly disappearing as the sound is no longer anchored to them. This is a remarkable difference and certainly one that changes the whole slant on what the Dual Core is worth as a pre-amp. As someone who listens to an increasing amount of acoustic music and voice, it's an attractive trade off for the nth degree of polish.
Finally, I tried the Anti-Mode Dual Core as a straight DSP processor between a transport and DAC. Essentially, the Dual Core is just applying EQ and passing the resultant signal straight on. This is clearly a happy position for the Dual Core as it's passing around a relatively robust digital data stream, without any analogue conversions and is entirely transparent in it's operation. The manifest qualities of the partnering components were allowed to shine, but the expected improvements in bass quality and imaging were immediately obvious. The tightening of bass takes nothing from music and delivers propulsion and a pitch definition to the bottom end, you'd be lucky to achieve in any normal room. It was in this system, that the homogenising of the stereo image was most apparent and indeed, the most impressive difference. You see, the system was relatively modest, but well matched.
The speakers in question were the Elipson Planet L 2-way standmounts. A speaker for which I have a lot of affection, save for their lack of bottom end and resultant limited headroom. The system is the Elipson Music Centre (more soon) which has a number of remarkable qualities including 2x120w of B&O Ice Power amplification AND a subwoofer output which, (hurrah!) high passes the speakers - it is a stereo with proper bass management. Feeding a Squeezebox, via the Anti-Mode Dual Core, into the Elispon MC and onto the Planet Ls and an SVS SB12, was a revelation.
Imaging is one of the qualities that impressed me most when reviewing the Planet Ls. So to have it resolutely shifted to another level is a sit up and take notice moment. The system as a whole thrives on a subwoofer sidestepping it's limitations and the Anti-Mode obviously could do a good job here. But this is also like feeding the digital output from the Dual Core into a spare S/PDIF input on your AV receiver, or processor to the same effect; that being to EQ the subwoofer and speakers as a collective whole. You can still EQ your subwoofers for multichannel use via the Anti-Mode's analogue in/outs and keep the slightly differing EQ profiles on diferent presets. That is an extra level of flexibility, you just can't get elsewhere.
- Superbly effective in it's primary role
- Very effective in it's secondary roles
- Flexible input options
- Well built
- Remote control is somewhat basic
- 24/96 digital input would be nice
- Nothing else
DSpeaker Anti-Mode 2.0 Dual Core Review
I'm buying one. I could end the review right there, as I've tried many EQs and yet stuck with a £100 live gig, rackmount refugee that is less than straight forward to use. So why the change? Well, it's for the following reasons that I'm giving the DSpeaker Anti-Mode 2.0 Dual Core a Reference Status.
First, it consistently gives reference quality, subwoofer EQ results, automatically and for little more input than moving a mic stand around and following a few basic rules. It's already achieved the best the opposition has to offer, but then it adds all the extra facilities to tune to taste and that moves it into a catagory of one.
Second, It has so many other uses and some of them are available at the same time as it's primary use. It can EQ my subs for 5.1 use via the analogue in/outputs and EQ the digital output of the Squeezbox into the processor, so it can cover both the subs and speakers for pure stereo use. Nothing else can do that.
Computer user? Input via USB, connect active speakers on your desktop, a subwoofer under the desk (you can use both analogue outputs simultaneously) and let the Dual Core sort it out and provide you with a decent pre-amp at the same time. There are loads of reasons to buy one, not least that if you stop using it in it's original role, then there's bound to be another role it can fulfil.
The only complaints are; It can't handle 24/96 and 24/192 digital inputs. This may bother some and the former would be nice, but that's not it's primary role. I also did test it in one system where the input levels that system generated, caused clipping on the analogue single ended input. This system is one where the gain of the amplifiers in use is lower than the norm, requiring higher than average input levels, compounded by the fact that levels we were playing it at were extremely high. I was unable to recreate the same set of circumstances in my more domestically oriented system. We didn't have the relevant balanced interconnects to hand, to see if that side stepped the issue in the other system, but hindsight is 20/20, as they say. DSpeaker are aware of the issue and think it can be addressed in the firmware in a future update. This also hints at the fact the current feature set my not be the last - user input in the field can help no end in future developments as our feedback testifies.
Ultimately, this is the best subwoofer EQ device I've tested to date. That it goes so far beyond that is, quite simply, brilliant. At only £680 it's cheaper than the best subwoofer EQ I'd previously tested and that makes for a mandatory 'Reference Status'. Go get your own, because this one is going nowhere.
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