Rythmik F12se vs KEF KC62

[Hexspa]

Not really, no. Keep in mind that a larger driver also means a bigger magnet and voice coil. F=ma. In theory you could probably build a large driver that was "slow" but it would have terrible frequency response and so it would be unusable. There have been some previous threads on this topic that you might find useful.

But what it boils down is that most of the important time domain characteristics of a speaker/subwoofer are in fact contained in a frequency response measurement. If there are significant impulse response issues then they will show up there as well. You can't simplify down to "driver size".

There are some edge cases where "speed"(typically measured as group delay for subs) can be an audible problem but this doesn't have anything to do with driver size, rather it's a result of the cabinet design, port tuning, and sometimes use of DSP. Smaller ported subs(eg 12" or less) with tuning in the audible range(>20hz) can have excessive group delay near their tuning frequency. But even then there's very little evidence that this is easy to hear or a big problem.

What causes "slow bass" is almost always overly excited room modes. There is a myth that smaller subwoofers are "faster" because they just don't play as low and thus don't excite those low frequency modes as much. The real way to fix this problem is with room correction EQ and multi-sub systems.

Old post but how do EQ and multiple subs deal with room resonances? I’ve been using absoption.

 

[Sancus]

Old post but how do EQ and multiple subs deal with room resonances? I’ve been using absoption.

Multiple subs compensate for room resonances because one sub can be used to compensate the others as long as they're placed independently. As an oversimplification, imagine one sub has a null at 40hz. The other sub has a null at 80hz. You cannot boost nulls with EQ, but you *can* use the sub that has a null at 80hz to compensate for the other one at 40hz and vice versa. Together, they can play free of nulls when individually it's impossible. Here are some measurements showing what can be achieved with this approach.

There are various tools/methods for achieving this but a popular cheap/free combination is a MiniDSP to EQ each sub + Multi-Sub Optimizer to calculate the filters, which is much more effective than trying to do it manually.

Absorption is still necessary above the sub crossover, but fortunately that is much more practical, since to actually absorb frequencies below 80hz takes special resonators and tuned traps or literal meters-thick broadband absorbers. Well, unless Dirac's spatial room correction actually works out, which will allow cancelling reflections with other speakers and could reduce or eliminate the need for absorption altogether.

 

[Willem]

What I find disappointing in the vast majority of consumer level stereo amplifiers is the lack of a high pass filter. Pro Audio amps have them and they would make integration with common that much easier. Even a basic high pass filter at 80 Hz would help a lot.

 

[Hexspa]

Multiple subs compensate for room resonances because one sub can be used to compensate the others as long as they're placed independently. As an oversimplification, imagine one sub has a null at 40hz. The other sub has a null at 80hz. You cannot boost nulls with EQ, but you *can* use the sub that has a null at 80hz to compensate for the other one at 40hz and vice versa. Together, they can play free of nulls when individually it's impossible. Here are some measurements showing what can be achieved with this approach.

There are various tools/methods for achieving this but a popular cheap/free combination is a MiniDSP to EQ each sub + Multi-Sub Optimizer to calculate the filters, which is much more effective than trying to do it manually.

Absorption is still necessary above the sub crossover, but fortunately that is much more practical, since to actually absorb frequencies below 80hz takes special resonators and tuned traps or literal meters-thick broadband absorbers. Well, unless Dirac's spatial room correction actually works out, which will allow cancelling reflections with other speakers and could reduce or eliminate the need for absorption altogether.

I'm genuinely shocked that adding subs can reduce ringing and will be investigating further, thanks.

Editing to comment about the 'meters-thick' criterion for absorption. Maybe we can define 'actually absorb'. If we can believe this calculator, we get pretty significant absorption with 24" (609.6mm) fluffy with resistivity of 3000 Pa•s/m2. 2m-thick ("meters-thick") enhances performance below 30Hz with a small trade off an octave up. Though people often think, not saying you, that you need to use a 1/4 wavelength-deep absorber to act on a frequency, even 4" (~100mm) of rigid acts on an 8' (~244cm) wavelength of 141Hz; though not as much as 24" of fluffy.

Given that, for a critical listening room, the EBU accepts a 25% increasing slope of decay below 200Hz, you can likely meet decay targets with no more than two feet of fluffy insulation in a room of reasonable dimensions and volume; reasonable meaning not a tiny cube. Yes, tuned absorbers can work but I'm speaking from the perspective of someone without the means to construct them.

This could be my heretofore bias toward frictional absorption but it's true nonetheless. Now I will read about multiple subwoofers

 

[Sancus]

Given that, for a critical listening room, the EBU accepts a 25% increasing slope of decay below 200Hz, you can likely meet decay targets with no more than two feet of fluffy insulation in a room of reasonable dimensions and volume; reasonable meaning not a tiny cube. Yes, tuned absorbers can work but I'm speaking from the perspective of someone without the means to construct them.

I was just going by the quarter wavelength rule, yeah you can get some effect with less than that. I think you'll find that for most people, 24" thick absorbers are off the table as well though haha. I am talking about regular domestic rooms, obviously studios and purpose-built home theaters CAN do this much sometimes, but even in a purpose built HT that is a lot of space used.

 

[Hexspa]

I was just going by the quarter wavelength rule, yeah you can get some effect with less than that. I think you'll find that for most people, 24" thick absorbers are off the table as well though haha. I am talking about regular domestic rooms, obviously studios and purpose-built home theaters CAN do this much sometimes, but even in a purpose built HT that is a lot of space used.

Thanks for your reply. All I can say about absorption targets and thicknesses is I aim for 20dB/decay within 150 ms from 63Hz to Schroeder with an even taper and +-10dB SPL at my listening position. To achieve that in an ~2500ft3 semi-rectangular apartment living room, I used 20 4” #8 mineral wool (IIG 1280) panels and 4.5 floor-to-ceiling fluffy super chunks (diagonal corner soffits).

While a sizable deployment, certainly not on the order of 24” all around. I agree that while propose-built rooms do go to that depth, it’s not necessary for modest results in domestic rooms.

Of course, as you mentioned, multiple subs seems to also be an option for controlling bass decay, SPL and distortion but I have no knowledge of it beyond the measurements you linked me to. As I said, I’m definitely going to look into that.

 

[CurtR]

"What I find disappointing in the vast majority of consumer level stereo amplifiers is the lack of a high pass filter. Pro Audio amps have them and they would make integration with common that much easier. Even a basic high pass filter at 80 Hz would help a lot."

I absolutely agree. The lack of any sort of high-pass capability is what killed the Technics su-r1000 for me... what a disastrous oversight. HOWEVER, I did find one: the Outlaw Audio receiver has a low/high pass filter! and two (but mono-blended) sub outs... It also has an "external processor" loop as well for slotting in a Loki or some such equalizer for finer grain tone control, plus pre-outs and main-ins. I'm quite intrigued by the Outlaw... some ballsy power too. Oh, and a tuner.

 

[Willem]

In my case I use an RME ADI-2 as my DAC/preamp and it has dual line level outputs. The XLR goes to the power amp, and the rca to the subwoofers. I have added a passive 80 Hz high pass filter between the ADI-2 and the power amp, and that is really quite effective. The subwoofer connection first goes into a miniDSP 2x4HD with filters calculated by MSO for my three subwoofers. The end result sounds pretty good, with clean bass across the entire listening space (this is the advantage of MSO over many other equalization systems). MSO was not easy to implement, however. The next part of the project is to include measurements for the main speakers as well, and equalize frequencies >80 Hz with the filters in the ADI-2.
The problem with a lot of consumer gear is that it is hard to connect subwoofers at line level, insert some dsp like the miniDSP 2x4HD, and hard to high pass the signal to the main speakers. A separate preamp/Dac and power amp combination is much easier to get right.