Has anybody heard the new KEF KF92 sub? What are your opinions?

[CurtR]

oh... I think the RSL just might be in the same league, sound-quality wise... not sure yet, but I'm gonna give it the old college try.

I like your idea of the two kc92 ... they look great, I'm sure they sound splendid, dual-opposed drivers, compact dimensionally and not too heavy to move. And, it sounds like you have a solution to the xlr issue.
I may "go there" too. I do not need ultimate output levels, as my listening levels tend to be under 90db, and even lower.

For me, a huge box and heavy weight is a deal-killer, which is what led me to the compact-er solutions investigations, like yourself, and which is why I'm not currently wrestling an RSL 12s into place.

 

[CurtR]

since you couldn't access the spreadsheet I've extracted a relevant comparison here

Manufacturer	Model (sorted by, second)	Converted to USD	# of Woofers	Woofer Size (in)	Type	Source of CEA-2010-A data. Shown as 2m Peak SPL.	Version Tested	15 hz	20 hz	25 hz	31.5 hz	40 hz	50 hz	63 hz	80 hz	Weight (lb)	H (in)	W (in)	D (in)	Volume (ft^3)	Footprint (W*D) (ft^2)
Rythmik	F12	1120	1	12	sealed	Brent Butterworth		95	97.6	100.7	107.5	112.3	113.1	114.4	113.6	75	15.8	15.8	17	2.4	1.9
KEF	KF92	2000	2	9	sealed	ErinsAudioCorner			86	91.6	95.4	101.1	103	104.4	106.3	44.1	13.9	13	14.2	1.5	1.3
	Difference	880​						N/A	11.6​	9.1​	12.1​	11.2​	10.1​	10​	7.3​	30.9​

As you can see from the data, the Rythmik F12 outperforms the KF92 by 11.6dB at 20Hz, and at 15Hz the KF92 was not able to register any passing score due to high distortion.
This means that at 20Hz one F12 has the equivalent output of roughly four KF92s, plus it has XLR inputs. The G22 has 6dB higher output at 20Hz than the F12. There is no need to use the rumble filter at all unless you are playing movies like "the edge of tomorrow" at very high levels.

Thank you very much for the chart extraction. And if the RSL 10s mk2 was placed on that chart too, one would see that it is right up there with either of those subs, down to 20 anyway, at $500 shipped, including tax.

However, as for the G22 ...I was considering it too, though its too large for my space, but I was talked out of it by Brian at Rhythmik; he said it's a more "intellectual" sub and that other choices will be better if you want some tactile texture. Brian did recommend the F12 instead, or two of 'em, for my purposes.

And I know there's a debate, but "more output" isn't necessarily the be all end all, in my opinion, unless cranking up the volume to ear-damaging levels is desired. But I get what you're saying, but also nobody is claiming the KEF as "best bang for the buck" (nor definitely not the ELAC, either). There are other considerations, from aesthetic to driver design preferences, like single front firing vs dual-opposed.

 

[waynel]

Thank you very much for the chart extraction. And if the RSL 10s mk2 was placed on that chart too, one would see that it is right up there with either of those subs, down to 20 anyway, at $500 shipped, including tax.

However, as for the G22 ...I was considering it too, though its too large for my space, but I was talked out of it by Brian at Rhythmik; he said it's a more "intellectual" sub and that other choices will be better if you want some tactile texture. Brian did recommend the F12 instead, or two of 'em, for my purposes.

And I know there's a debate, but "more output" isn't necessarily the be all end all, in my opinion, unless cranking up the volume to ear-damaging levels is desired. But I get what you're saying, but also nobody is claiming the KEF as "best bang for the buck" (nor definitely not the ELAC, either). There are other considerations, from aesthetic to driver design preferences, like single front firing vs dual-opposed.

RSL is good and one of the best values. It will perform better at 20Hz (by 2dB) but worse at 16Hz (by 6dB) than the F12 and is a ported design so there is a possibility of port noise. Subwoofers are all about output and you need more output at sub-bass frequencies than you seem to think. The ear is not sensitive at these very low frequencies and 100dB at 20Hz is not loud. The KEF is a pretty poor performer regardless of price, It's not even a good performer for its size.

 

[JimA84]

since you couldn't access the spreadsheet I've extracted a relevant comparison here

Manufacturer	Model (sorted by, second)	Converted to USD	# of Woofers	Woofer Size (in)	Type	Source of CEA-2010-A data. Shown as 2m Peak SPL.	Version Tested	15 hz	20 hz	25 hz	31.5 hz	40 hz	50 hz	63 hz	80 hz	Weight (lb)	H (in)	W (in)	D (in)	Volume (ft^3)	Footprint (W*D) (ft^2)
Rythmik	F12	1120	1	12	sealed	Brent Butterworth		95	97.6	100.7	107.5	112.3	113.1	114.4	113.6	75	15.8	15.8	17	2.4	1.9
KEF	KF92	2000	2	9	sealed	ErinsAudioCorner			86	91.6	95.4	101.1	103	104.4	106.3	44.1	13.9	13	14.2	1.5	1.3
	Difference	880​						N/A	11.6​	9.1​	12.1​	11.2​	10.1​	10​	7.3​	30.9​

As you can see from the data, the Rythmik F12 outperforms the KF92 by 11.6dB at 20Hz, and at 15Hz the KF92 was not able to register any passing score due to high distortion.
This means that at 20Hz one F12 has the equivalent output of roughly four KF92s, plus it has XLR inputs. The G22 has 6dB higher output at 20Hz than the F12. There is no need to use the rumble filter at all unless you are playing movies like "the edge of tomorrow" at very high levels.

Yes, but the Rythmik is a single driver and much heavier. As I said if I went by price/CEA specs alone:

 

[waynel]

There is nothing wrong with a single driver and you can decide if 75 lbs is more than you can move around . Is there any objective measurement you will consider?

 

[JimA84]

This Monoprice 16 inch has pretty impressive objective CEA-2010 results and it's less money than the KEF KC92.

In the size/weight range I am interested in, the KC92 seems quite satisfactory. The measurements I have seen are significantly better than the ones you cite. Erin's measuements are typically reliable but also conservative. Besides, if I am not satisfied I can simply return it, in which case I might well try the ELAC DS1000 and if that is also inadequate I would likely just resign myself to the Monoprice 16" model.

I doubt the main channel speakers (Newform Research Last Dance) I am considering can achieve much more than 105 dB with six Purifi PTT4.0 4 inch drivers.

I'm not looking to compete with Grand Funk Railroad for dB levels since I value my hearing. I wore earplugs when I saw them live in 1974.

The KC92 seems like a reasonable match for the Purifi 4 inch midbasses in the Newform Research Last Dance speakers.

The processor I am considering can do independent Dirac EQ for five KEF KC92s if needed.

I like the KC92. I like the ELAC DS1000. I like the Monoprice 16 inch.

So one of those will likely be my choice.

There are certainly other options that may appeal to other people.

For instance the Dynaudio Sub 6 is another quality compact subwoofer of similar size to the KEF KC92 and ELAC DS1000.

Certainly worth consideration.

 

[waynel]

This Monoprice 16 inch has pretty impressive objective CEA-2010 results and it's less money than the KEF KC92.

In the size/weight range I am interested in, the KC92 seems quite satisfactory. The measurements I have seen are significantly better than the ones you cite. Erin's measuements are typically reliable but also conservative. Besides, if I am not satisfied I can simply return it, in which case I might well try the ELAC DS1000 and if that is also inadequate I would likely just resign myself to the Monoprice 16" model.

I doubt the main channel speakers (Newform Research Last Dance) I am considering can achieve much more than 105 dB with six Purifi PTT4.0 4 inch drivers.

I'm not looking to compete with Grand Funk Railroad for dB levels since I value my hearing. I wore earplugs when I saw them live in 1974.

The KC92 seems like a reasonable match for the Purifi 4 inch midbasses in the Newform Research Last Dance speakers.

The processor I am considering can do independent Dirac EQ for five KEF KC92s if needed.

I like the KC92. I like the ELAC DS1000. I like the Monoprice 16 inch.

So one of those will likely be my choice.

There are certainly other options that may appeal to other people.

For instance the Dynaudio Sub 6 is another quality compact subwoofer of similar size to the KEF KC92 and ELAC DS1000.

Certainly worth consideration

The other "measurements" you mention are uncontrolled and in a random room. The measurements in this spreadsheet are controlled and outdoors . I thought you were an engineer, you should know that you can't measure speakers with any degree of accuracy in a random room (without a kllippel).

 

[JimA84]

I don't intend to listen to them outdoors. I don't think my neighbors would like that.

A truly anechoic environment is better than "outdoors," though there is some degree of logic to the point that nobody is likely to listen to music in an anechoic environment, although PA systems may be used outdoors.

KLIPPEL is primarily aimed at quality control and assurance applications in manufacturing. Thus the actual metrics are less important than consistency.

It is true that for reproducible results you need some kind of standardized protocol which is why I said some time ago that we should develop one that reflects real world applications, such as a variety of standardized room environments.

This has been the practice in benchmarking computers for decades.

I am also a scientist and as such I know that engineers are fond of measuring pointless things that are easy to quantify.

 

[waynel]

I don't intend to listen to them outdoors. I don't think my neighbors would like that.

A truly anechoic environment is better than "outdoors," though there is some degree of logic to the point that nobody is likely to listen to music in an anechoic environment, although PA systems may be used outdoors.

KLIPPEL is primarily aimed at quality control and assurance applications in manufacturing. Thus the actual metrics are less important than consistency.

It is true that for reproducible results you need some kind of standardized protocol which is why I said some time ago that we should develop one that reflects real world applications, such as a variety of standardized room environments.

This has been the practice in benchmarking computers for decades.

I am also a scientist and as such I know that engineers are fond of measuring pointless things that are easy to quantify.

You quite honestly don't know what you are talking about.

 

[Mnyb]

A thing to investigate is that transformer coupled balanced to single ended converters migth not perform well in the frequency extremes like bass and treble and some can easily saturate in the bass .

 

[JimA84]

You quite honestly don't know what you are talking about.

The DoD, the NIH, IBM, HP, Oracle and other employers might differ with that opinion, but you are certainly welcome to say so.

 

[waynel]

The DoD, the NIH, IBM, HP, Oracle and other employers might differ with that opinion, but you are certainly welcome to say so.

Dunning-Kruger say otherwise

 

[CurtR]

You quite honestly don't know what you are talking about.

I prefer real-world performance. My room is not an anechoic chamber. There WILL BE room interaction with the sub. Anechoic measurements, and outdoor measurements, while interesting and somewhat useful, do not tell the whole story, by any means, and are disconnected from the way people actually use their equipment.

 

[CurtR]

This Monoprice 16 inch has pretty impressive objective CEA-2010 results and it's less money than the KEF KC92.

In the size/weight range I am interested in, the KC92 seems quite satisfactory. The measurements I have seen are significantly better than the ones you cite. Erin's measuements are typically reliable but also conservative. Besides, if I am not satisfied I can simply return it, in which case I might well try the ELAC DS1000 and if that is also inadequate I would likely just resign myself to the Monoprice 16" model.

I doubt the main channel speakers (Newform Research Last Dance) I am considering can achieve much more than 105 dB with six Purifi PTT4.0 4 inch drivers.

I'm not looking to compete with Grand Funk Railroad for dB levels since I value my hearing. I wore earplugs when I saw them live in 1974.

The KC92 seems like a reasonable match for the Purifi 4 inch midbasses in the Newform Research Last Dance speakers.

The processor I am considering can do independent Dirac EQ for five KEF KC92s if needed.

I like the KC92. I like the ELAC DS1000. I like the Monoprice 16 inch.

So one of those will likely be my choice.

There are certainly other options that may appeal to other people.

For instance the Dynaudio Sub 6 is another quality compact subwoofer of similar size to the KEF KC92 and ELAC DS1000.

Certainly worth consideration.

nice but how does it fit physically and aesthetically for you, in your room? To me, it looks monstrous and I wouldn't want to have it in the house, no matter how "awesome" it might sound... that's a personal/lifestyle/aesthetic issue.

You know, I see a lot of crit of the Kf92 and theoretical crit of the kc92... by people who don't own them. But, people who own them tend to like them a lot. Same trend with the kc62, for that matter.

 

[sigbergaudio]

I prefer real-world performance. My room is not an anechoic chamber. There WILL BE room interaction with the sub. Anechoic measurements, while interesting, do not tell the whole story, by any means, and are disconnected from the way people actually use their equipment.

But Jim above recently refused to believe an estimated in room response from another manufacturer, so it's hard to win / make everybody happy. How the room affects the sub performance will also be different in every room, so anechoic data will at least be somewhat comparable across manufacturers and products, while an estimated in room response or max spl will be approximate.

 

[CurtR]

RSL is good and one of the best values. It will perform better at 20Hz (by 2dB) but worse at 16Hz (by 6dB) than the F12 and is a ported design so there is a possibility of port noise. Subwoofers are all about output and you need more output at sub-bass frequencies than you seem to think. The ear is not sensitive at these very low frequencies and 100dB at 20Hz is not loud. The KEF is a pretty poor performer regardless of price, It's not even a good performer for its size.

I have an RSL 10s mk2 sitting here right now. Within the next day or two I will do my in-room objective measurements and report back, like I've mentioned before. At the very least, it'll be a good exercise in a "value" sub vs. a "luxury" sub (the ELAC ds1000, which I also currently have in-room). I don't think the RSL, or the mk2 anyway, has really been dinged for port noise, and at least on this new one I have the port has rounded edges etc. ... I don't anticipate port noise issues, at least at the levels I listen ... but again, soon we shall see and hear in my particular real world.

(I save my "really loud" experiences for rock concerts, and I bring Experience earplugs w me too for if I feel the concert sound is getting dangerous... good recommendation, btw, those Experience earplugs; they're designed for concerts and reduce overall decibel levels but still allow most of the frequencies to pass through, with perhaps a little muting of the upper freqs, and are mechanically adjustable for volume level. They come with a little plastic round case to slip in pocket.)

need sub-bass more for what? depends on what one is looking for, one's goals... perhaps I'm not enthusiastic about sending earthquake-like shock waves to the neighbors, nor to impose them on other members of my household, for that matter. I don't care at all about "Edge of Tomorrow" ... blech, even, to that one.

I do like a well-integrated quality sub, don't get me wrong... but on the other hand, I ran with Epi 100 speakers (8" woofer, roll off at about 42) for years and rarely if ever thought the bass was lacking and in fact it was very high quality, tickled the inner ear. Now, I have Q Acoustics Concept 50, which are down about 6db at 42, and they sound great as-is, but yes on both the Epi and the Concept 50 having a sub handle 20-40 or 45 is a nice bonus, for sure, for the extra kick and "atmospherics."

But I don't need nor even necessarily want "tremendous output below 20hz"... if there's a little bit down there, OK cool that's fine but certainly not my focus.

 

[JimA84]

In case I wasn't clear, I was talking about the suitability of a couple KC92 subwoofers to complement a brace of Newform Research Last Dance ribbons in an average listening room.

Not abstract measurements or even industrial psychology hypotheses which BTW look like the Peter Principle.

I really don't understand why you seen so violently opposed to the notion of using a pair of KEF KC92s with a brace of Newform Research Last Dance speakers in a 5.2 system.

As for Dunning-Kruger, I proved to HP in 1993 that their Itanium processor would never deliver what they assumed.

This assumption by HP was based on a since discredited reseach paper that reasonably but wrongly speculated that there was a huge amount of potential for parallel execution in existing computer codes due to peephole optimization and local runtime instruction reordering missing out on these opportunities.

I had one of the first DEC Alpha systems, and they included very advanced compilers for C/C++ and Fortran that could do exhautive broad and deep source code analysis for parallel execution.

More or less similar to what HP engineers tried and ultimately failed to produce for the Itanium.

Using this option required compiling the entire application at once even if you edited a single source file.

I benchmarked a very large representative set of biomedical and genomic applications and found around a 2.5 percent or less improvement in runtime performance. Not statistically significant.

The other problem is that EPIC assumes that you can optimize the execution at compile time with no knowledge of runtime branch directions.

In the rigorous application of this hypothesis they threw away all the benefits of runtime branch prediction, speculative execution and instruction reordering.

All for a compile time model with zero knowledge of runtime data values.

To their credit, HP and Intel engineers ultimately managed to make Itanium competitive, largely by equipping it with an insane amount of costly and power hungry cache memory.

Sort of like putting a 10,000 HP engine in a dump truck and calling it a Formula 1 car.

But it really did work. I hand built and configured some HP Itanium systems with very good and cost effective performance running SAP over Oracle and HP-UX with HP Serviceguard and a combination of nPar and vPar partitioning that permitted literally abruptly cutting the power to half the cluster with no loss of service.

I could also achieve record levels of performance by tuning the Fibre Channel interfaces and using the real time scheduler in HP-UX to optimize the Oracle database performance.

Unfortunately by the time we got competitive performance from the Itanium architecture, the industry had pretty much abandoned it and moved on to the Xeon architecture which was pretty much a commodity product due to demand for inexpensive massively parallel systems and fast gaming PCs.

So Intel chose to EOL the Itanium processor for business profit reasons and indeed I can't blame them. It's just kind of sad that it took HP-UX down with it as collateral damage.

Neither Itanium nor Xeon are very good architectures. They just won out due to market dynamics.

Kind of like Bose speakers and Beats headphones.

With Xeon we are now firmly locked in to the horribly flawed 1984 IBM-PC architecture that was adopted almost as a joke.

Grasping defeat from the jaws of victory.

 

[JimA84]

But Jim above recently refused to believe an estimated in room response from another manufacturer, so it's hard to win / make everybody happy. How the room affects the sub performance will also be different in every room, so anechoic data will at least be somewhat comparable across manufacturers and products, while an estimated in room response or max spl will be approximate.

This discussion kind of reminds me of people debating the merits of various firearm cartridges.

 

[waynel]

In case I wasn't clear, I was talking about the suitability of a couple KC92 subwoofers to complement a brace of Newform Research Last Dance ribbons in an average listening room.

Not abstract measurements or even industrial psychology hypotheses which BTW look like the Peter Principle.

I really don't understand why you seen so violently opposed to the notion of using a pair of KEF KC92s with a brace of Newform Research Last Dance speakers in a 5.2 system.

As for Dunning-Kruger, I proved to HP in 1993 that their Itanium processor would never deliver what they assumed.

This assumption by HP was based on a since discredited reseach paper that reasonably but wrongly speculated that there was a huge amount of potential for parallel execution in existing computer codes due to peephole optimization and local runtime instruction reordering missing out on these opportunities.

I had one of the first DEC Alpha systems, and they included very advanced compilers for C/C++ and Fortran that could do exhautive broad and deep source code analysis for parallel execution.

More or less similar to what HP engineers tried and ultimately failed to produce for the Itanium.

Using this option required compiling the entire application at once even if you edited a single source file.

I benchmarked a very large representative set of biomedical and genomic applications and found around a 2.5 percent or less improvement in runtime performance. Not statistically significant.

The other problem is that EPIC assumes that you can optimize the execution at compile time with no knowledge of runtime branch directions.

In the rigorous application of this hypothesis they threw away all the benefits of runtime branch prediction, speculative execution and instruction reordering.

All for a compile time model with zero knowledge of runtime data values.

To their credit, HP and Intel engineers ultimately managed to make Itanium competitive, largely by equipping it with an insane amount of costly and power hungry cache memory.

Sort of like putting a 10,000 HP engine in a dump truck and calling it a Formula 1 car.

But it really did work. I hand built and configured some HP Itanium systems with very good and cost effective performance running SAP over Oracle and HP-UX with HP Serviceguard and a combination of nPar and vPar partitioning that permitted literally abruptly cutting the power to half the cluster with no loss of service.

I could also achieve record levels of performance by tuning the Fibre Channel interfaces and using the real time scheduler in HP-UX to optimize the Oracle database performance.

Unfortunately by the time we got competitive performance from the Itanium architecture, the industry had pretty much abandoned it and moved on to the Xeon architecture which was pretty much a commodity product due to demand for inexpensive massively parallel systems and fast gaming PCs.

So Intel chose to EOL the Itanium processor for business profit reasons and indeed I can't blame them. It's just kind of sad that it took HP-UX down with it as collateral damage.

Neither Itanium nor Xeon are very good architectures. They just won out due to market dynamics.

Kind of like Bose speakers and Beats headphones.

With Xeon we are now firmly locked in to the horribly flawed 1984 IBM-PC architecture that was adopted almost as a joke.

Grasping defeat from the jaws of victory.

Several of us have tried to help you to understand how subwoofers are measured and characterized objectively , taking variance in room out of the equation. With room variation factors controlled for, you can then model how the subs will perform in your room. The spreadsheet that sweetchaos compiled is a great resource but you refuse to or are unable to look at. I am giving up on you. You are not the only engineer or scientist here on this board btw.

 

[JimA84]

nice but how does it fit physically and aesthetically for you, in your room? To me, it looks monstrous and I wouldn't want to have it in the house, no matter how "awesome" it might sound... that's a personal/lifestyle/aesthetic issue.

You know, I see a lot of crit of the Kf92 and theoretical crit of the kc92... by people who don't own them. But, people who own them tend to like them a lot. Same trend with the kc62, for that matter.

That's my whole point. I could buy a huge $20,000 JL or Wilson Audio's Thor's Hammer, but there seems to be a mindset that you need a nuclear weapon when a JDAM would do