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Lowther USA designed PM8A/Tone Tubby open baffle
2014 Midwest Audiofest Tent Sale & Vintage Audio Swap
DSPeaker Dualcore 2.0 Room Correction Review
Bass is a problem in most rooms, whether it is a noticeable issue or not is obviously down to the acoustics, the user, the music, the positioning etc etc – In my space I’ve never had a bass performance I’ve been happy with. It’s a big space and small changes in seating location and speaker placement have had frankly HUGE effects on bass performance.
It’s a generally accepted rule that above 200Hz it’s the characteristics of the speakers and electronics that are the dominant factor in the ‘sound’ of a system, the lesser effect coming from the general ‘liveliness’ of the room with slap and echo noise etc. Below 200Hz and it’s the effects of room modes, nodes and reverb standing waves that will have a more dominant effect on the sound. Room modes create a series of peaks and dips throughout the room, areas where the volume is actually higher or lower than that coming out of the speakers.
There are two solutions to these problems, DSP to ‘correct’ the output at given frequencies and acoustic room treatment to minimise the dominance the room has over the output from the speakers. I’ve tried both, both with varying levels of success, what I do have now though is a deep experience of my room, it’s ‘issues’ and in measuring it with the XTZ mic kit (and now my Studio EQ kit…) across a very wide range of speakers that have been through here. One interesting point that just goes to prove the above points regarding the room being the dominant player, recent tests with Living Voice Avatars, the Horning Agathons and my own P17 Open baffles has shown the same major dips and bumps in the bass performance – sure, the scale, weight, speed and depth are all a bit different but the response plots are unnervingly similar…. Now with a couple of BK subwoofers to try and integrate too I couldn’t pass up the chance to give the much lauded Dualcore a bash in here.
First impressions – it’s a very nice professionally built bit of kit, solid, a perfect match for my Audiolab MDAC in appearance too!
It’s well featured, with balanced and single ended analogue outputs, or optical digital output to keep things in the digital domain and still feed your DAC and analogue or digital USB/optical inputs – although sadly missing coax spdif – more on this later. It converts every signal, analogue or digital into its own digital stream and can function as a digital pre too, although the side is let down a little by the poor remote and the complete reliance on this for ALL functions. As a ‘set-up and leave it’ remote, it’s fine, just not something I’d be totally happy with on a day to day basis.
Set-up is a total piece of cake, mic in, go to calibrations, choose your system configuration from a very simple user interface, press start, go and make some tea and try to keep the dog quiet (as that had some very bizarre effects on the output first time around…). You are then presented with the output a few minutes later, a nice graph displaying the room measurements before and after the Dualcore’s DSP has worked it’s magic. I won’t go through the intricacies of the set-up options as you could go on for ever in here, but it can be tweakers heaven or a simple one-press operation, the standard set-up ONLY corrects for bumps, pulling output down at given frequencies, it does NOT compensate for dips or suckouts although you can program in frequency lifts manually to try and get a flat response – there are good reasons why this isn’t a good idea though (again, more on this later…).
So how did I get on? First loop was very fast and showed the usual bumps at 20, 60 and 120Hz in here along with nasty drops at 24 and 36Hz. Aside from the dips, the Dualcore had engineered an extremely flat response knocking levels down by up to 15dB in places which is huge. The sound was instantly cleaner, although not ‘missing’ bass which I honestly expected to be the first impression, it was less ‘resonant’, more textured and more pleasing on the ear with known problem tracks now missing that omnidirectional boom I’m so conscious of as those peaks are hit.
I then worked to address the dips, upping the level and crossover on the subs, adjusting phase and siting slightly – relying more and more on the Dualcore to do it’s job. Final pass as you can see is a tremendous response from an in room system measurement, still a couple of suck-outs but far less. Again, the improvement in depth and cleanliness of the bass was instantly noticeable – this is what flat sounds like! Very impressive indeed.
However, it wasn’t all plain sailing, there are some clear issues and disadvantages – both of this unit, and of the principle in general.
Let’s cover the Dualcore first. The lack of high bit support is unforgiveable in this day and age I feel, I’ve a load of 24/96 and 24/88 material, none of which will work with this. The recent firmware allows the dualcore to accept high def material, it will downsample it all. The Dualcore DOES work purely in the digital domain but every signal, including redbook 16/44 is re-sampled to the Dualcores native 16/48, so there is a whole loop of digital resampling to mess with your precious signal, even though you can still output the digital stream to your own DAC and in practice I’m not sure this resampling will really make any noticeable difference. Then there is the issue with the inputs, optical only is an issue for sure, but more disconcerting was the massive drop in level I experienced with it, A-B switching from co-ax into DAC from the SBT and optical into DAC from the Dualcore, I reckon resulted in a 10dB level difference, that’s a huge loss of headroom, especially in systems with passive or digital attenuation as you can’t add the gain back in further down the chain! Finally, I had some pretty significant distortion issues with clear popping, cracking and clicking distortion on bass lines. To be fair though, this was intermittent and the guys at DSPeaker seem to be aware of it, so perhaps firmware solutions will be forthcoming.
Then there is the generic issue of DSP vs acoustic treatment. The problem with DSP is that it ONLY works at that one measured location, imagine dumping 15dB of 60Hz bass because you are sitting in a room node, move 6” out of that room mode and the 15dB reduction is still there but the node isn’t, result, a huge drop off in bass at that frequency…. Same is true for lifts. In other words, if you happen to be sitting in an area where there is a dip – you will add more bass to get it to sound right to your ears, but when you move outside of the dip, it’s hugely overcompensated. As I mentioned earlier, there is another problem with correcting for dips too – to demonstrate, imagine a hypothetical case where you sitting in a perfect null point, where the standing waves are cancelling each other out – generating a situation where the amplitude of that bass frequency is 0dB – in which case it doesn’t matter how much DSP boost is applied you would still have a 0dB signal! This is so called Narrow Band Parametric EQ and again, it works for amplitude in a given spot but doesn’t deal with reverberation of the room and decay of the bass, another huge issue for ‘cleanliness’ and clear dynamics. That also has to be dealt with in order for the room to present music accurately and cannot be done with DSP alone.
Therefore, in summary, I’m certainly not pointing any real fault at the Dualcore, just very conscious to point out that IMHO you still need room acoustic treatment. You need to use the two tools in parallel, get the room set-up and minimise it’s effects as best you can and then tweak with the DSPs afterwards! Active room correction has definitely got a place, DSPeaker have clearly shown that the technology is pretty much at the mass market level now and the results for me were very very good, but again, I also have 4 monster bass traps and a dozen panels around the room. The effect of the ‘room’ on the acoustic and performance of our precious systems is so overlooked and one has to applaud DSPeaker for making such an effective DSP solution accessible. It’s perhaps still a little immature in it’s implementation (although I’d certainly consider buying one if the foibles were addressed in a v2…). If nothing else it will show a user what CAN be achieved and hopefully then encourage a full solution using room treatment and DSP, for this then, a true landmark product, considering what it can do for the price it’s superb.
Discuss the review here
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