Just before Easter I took a punt on a BK Monolith subwoofer that was being sold cheaply locally to me. I'm very glad I did .
Had I simply relied on the adjustments on the sub to integrate it with my main speakers I don't think I'd be using it for anything more than TV/movies though, but with the aid of my miniDSP 2x4 HD I've now got it working well for music too. The important functions of the miniDSP are that it provides:
To be able to use these capabilities I'm running my miniDSP as both a DAC and digital pre-amp, with outputs being fed directly into my power amp for the main speakers, as well as a mono output going to the (powered) sub.
My main speakers are Meadowlark Shearwater HotRods which have a specified output down to 35 Hz (-3 dB) so they are not what I think most would consider bass-light. The upshot of adding the sub has though been a significant improvement, giving a much more solid, powerful bass response that is still punchy and tuneful rather than just being one, big boomy mess (as bad systems with subs easily can be in my experience). This gels with what's going on at higher frequencies to be, well, just better! Oh, and of course it's good for TV/movies too .
For those of a nervous disposition I should probably warn you that I'm now going to post some graphs. Quite a few in fact. So here's your chance to escape this thread without hopefully too much distress if you wish...
Still here? OK. Here are two graphs showing first the left channel response and then the right, with the grey curves being just the Shearwater's on their on and the coloured curves being what I've achieved with the Monolith added (and with EQ applied to the sub only).
The crossover from mains to sub is at 120 Hz, using 48 dB/octave Linkwitz-Riley filters. The comparisons are slightly unfair to my main speakers in that I optimised their position with the crossover to the sub in mind (i.e. not worrying what happened below about 80 Hz) but I couldn't make things much better than shown. The crossover frequency is higher than I'd originally intended but was primarily chosen as this was a region of good phase agreement between the left and right mains*, allowing for good matching to the sub and therefore a reasonably well-behaved crossover. As you'd expect I was concerned that 120 Hz might be too high, such that the sub would be obviously localisable but I don't fine that it is. A significant factor in this will be the sharp crossover roll-off. As examples, both the sub's own crossover control (which I bypass) and that applied by my blu-ray player, roll-off much more slowly, so whilst I could nominally set them to a more typical 80 Hz crossover frequency they would both be outputting audible signal to much higher frequencies than with my current setup.
* For the steady-state response. First arrivals signals from the main speakers are of course in-phase across the whole bass region, but what we hear at these frequencies is dominated by the steady-state reached once reflected signals are added in.
The EQ applied to the sub has no net boosts applied, and I took care that the filters themselves did not introduce significant time domain ringing (as judged by filter RT60s in REW being < 350 ms). I could of course apply EQ to my main speakers run on their own to make the comparisons above look rather less extreme but the results would not be as good as with the sub. This is because having an entirely separate gain control on the sub means I've been able to sacrifice a bit of its headroom to achieve a flatter response. My system still plays louder than I could comfortably listen to without sub output compression occurring though.
These graphs are at a position where the centre of my head would be. Yes there is variation in performance away from this location but the result is still far better than what I'd get with the main speakers alone (the response of which also varies with position of course).
Finally, for the few people who might be interested, here are waterfall plot comparisons for the right channel:
What I'm working on right now is experimenting with adding some acoustic panels to my room which both changes the required EQ and affects the decay times, but I thought I'd post what I'd achieved under 'normal' conditions first.
Had I simply relied on the adjustments on the sub to integrate it with my main speakers I don't think I'd be using it for anything more than TV/movies though, but with the aid of my miniDSP 2x4 HD I've now got it working well for music too. The important functions of the miniDSP are that it provides:
- A proper crossover between the main speakers and sub (the mains are no longer run full-range)
- Time delay adjustment to get good phase matching over the crossover region
- Equalisation to help manage room modes (which I'm applying only to the sub signal, not the main speakers)
To be able to use these capabilities I'm running my miniDSP as both a DAC and digital pre-amp, with outputs being fed directly into my power amp for the main speakers, as well as a mono output going to the (powered) sub.
My main speakers are Meadowlark Shearwater HotRods which have a specified output down to 35 Hz (-3 dB) so they are not what I think most would consider bass-light. The upshot of adding the sub has though been a significant improvement, giving a much more solid, powerful bass response that is still punchy and tuneful rather than just being one, big boomy mess (as bad systems with subs easily can be in my experience). This gels with what's going on at higher frequencies to be, well, just better! Oh, and of course it's good for TV/movies too .
For those of a nervous disposition I should probably warn you that I'm now going to post some graphs. Quite a few in fact. So here's your chance to escape this thread without hopefully too much distress if you wish...
Still here? OK. Here are two graphs showing first the left channel response and then the right, with the grey curves being just the Shearwater's on their on and the coloured curves being what I've achieved with the Monolith added (and with EQ applied to the sub only).
The crossover from mains to sub is at 120 Hz, using 48 dB/octave Linkwitz-Riley filters. The comparisons are slightly unfair to my main speakers in that I optimised their position with the crossover to the sub in mind (i.e. not worrying what happened below about 80 Hz) but I couldn't make things much better than shown. The crossover frequency is higher than I'd originally intended but was primarily chosen as this was a region of good phase agreement between the left and right mains*, allowing for good matching to the sub and therefore a reasonably well-behaved crossover. As you'd expect I was concerned that 120 Hz might be too high, such that the sub would be obviously localisable but I don't fine that it is. A significant factor in this will be the sharp crossover roll-off. As examples, both the sub's own crossover control (which I bypass) and that applied by my blu-ray player, roll-off much more slowly, so whilst I could nominally set them to a more typical 80 Hz crossover frequency they would both be outputting audible signal to much higher frequencies than with my current setup.
* For the steady-state response. First arrivals signals from the main speakers are of course in-phase across the whole bass region, but what we hear at these frequencies is dominated by the steady-state reached once reflected signals are added in.
The EQ applied to the sub has no net boosts applied, and I took care that the filters themselves did not introduce significant time domain ringing (as judged by filter RT60s in REW being < 350 ms). I could of course apply EQ to my main speakers run on their own to make the comparisons above look rather less extreme but the results would not be as good as with the sub. This is because having an entirely separate gain control on the sub means I've been able to sacrifice a bit of its headroom to achieve a flatter response. My system still plays louder than I could comfortably listen to without sub output compression occurring though.
These graphs are at a position where the centre of my head would be. Yes there is variation in performance away from this location but the result is still far better than what I'd get with the main speakers alone (the response of which also varies with position of course).
Finally, for the few people who might be interested, here are waterfall plot comparisons for the right channel:
What I'm working on right now is experimenting with adding some acoustic panels to my room which both changes the required EQ and affects the decay times, but I thought I'd post what I'd achieved under 'normal' conditions first.
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