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

[waynel]

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.

To sound as loud as 55dB in the midrange you need about 105dB at 20Hz and bear in mind that almost all music has a spectrum that is tilted down as frequency increases so you'll need even more sub bass headroom.

 

[sigbergaudio]

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

How so?

 

[CurtR]

To sound as loud as 55dB in the midrange you need about 105dB at 20Hz and bear in mind that almost all music has a spectrum that is tilted down as frequency increases so you'll need even more sub bass headroom.

Thank you, and I do understand the concept, but it doesn't bother me. And, I don't see many actual RSL nor KEF users complaining about "not enough bass"... and indeed a more frequent complaint I've seen by users is "have to turn it down because my neighbors in the house next door complained" type of issue. And, as I've said, I was quite satisfied with 42 hz of the Epi 100 for many years... so a some extra bonus bass down lower is nice as a bonus, as an extra kick. There's psychoacoustic measures and theory, and there's real-world everyday use in my home. If I want more bass while I'm listening, I can use tone control (Marantz Ruby amp bass control is centered at 20hz), or crossover low and raise the gain, or some combination thereof... but you know what I rarely do. There used to be loudness switches, too... and Yamaha has their variable loudness control to this day... for some compensation. Again, thank you for your engagement and interesting charts etc. too... I do appreciate it.

 

[CurtR]

How so?

like "a .50 cal is clearly superior" vs. a 9mm, but it rather depends on the application.

 

[JimA84]

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.

The point is that how subwoofers are measured "objectively" is largely irrelevant to how they will perform in a given room.

More importantly how they sound.

In attempting to produce reproducible results you have effectively made them irrelevant

In the old days people rated computer processors on "mips."

Cool, but it was completely irrelevant to real world scenarios.

Yeah, you could "objectively" compare processors at a completely pointless task.

We grew beyond that. Indeed in the old days you could artificially inflate the benchmark performance by expanding the cache or other tricks.

If you look at computer benchmarks over the last 30 years or do they are a spectrum of applications that attempt to test performance on real world meaningful tasks that are representative of what people use these systems for.

Subwoofer metrics have lagged into the "mips" realm. Easy to standardize and measure, but largely irrelevant to real world performance and quality of experience in realistic conditions.

Kind of like firearms evaluations in the military realm which looked promising but didn't work in application.

The unfortunate reality is that the ease of quantifying and standardizing a metric is inversely related to its value or relevance.

This is why the bit of humor about engineers liking to measure pointless things that are easy to quantify yet often have dubious relevance to real world scenarios. After all we engineers are primarily employed to measure things.

Since MBAs rule and hold the purse strings, deliverables are essential to keeping a job even if they effectively worthless.

I sincerely believe that it would be useful to develop a measurement protocol for subwoofers that, like the way we use various applications to measure CPU performance, we present subwoofers with a variety of realistic use models designed not only to challenge their weaknesses but to obfuscate attempts to design them to exploit the measurement paradigm to artificially inflate performance ratings.

I wish that I had the resources to do this but I hope that I can inspire someone to develop this instead of simply bickering about the quarterback denied the touchdown because of the official's flag.

 

[JimA84]

How so?

Well, the FBI decided to go with the Glock craze with 9mm with bigger magazines until they got slaughtered in a gunfight against a drug cartel in Miami.

 

[JimA84]

To sound as loud as 55dB in the midrange you need about 105dB at 20Hz and bear in mind that almost all music has a spectrum that is tilted down as frequency increases so you'll need even more sub bass headroom.

Actually RSL make some very pretty subwoofers. They may not be measured as deep as some other products but seem to be well made.

 

[JimA84]

The point is that how subwoofers are measured "objectively" is largely irrelevant to how they will perform in a given room.

More importantly how they sound.

In attempting to produce reproducible results you have effectively made them irrelevant

In the old days people rated computer processors on "mips."

Cool, but it was completely irrelevant to real world scenarios.

Yeah, you could "objectively" compare processors at a completely pointless task.

We grew beyond that. Indeed in the old days you could artificially inflate the benchmark performance by expanding the cache or other tricks.

If you look at computer benchmarks over the last 30 years or do they are a spectrum of applications that attempt to test performance on real world meaningful tasks that are representative of what people use these systems for.

Subwoofer metrics have lagged into the "mips" realm. Easy to standardize and measure, but largely irrelevant to real world performance and quality of experience in realistic conditions.

Kind of like firearms evaluations in the military realm which looked promising but didn't work in application.

The unfortunate reality is that the ease of quantifying and standardizing a metric is inversely related to its value or relevance.

This is why the bit of humor about engineers liking to measure pointless things that are easy to quantify yet often have dubious relevance to real world scenarios. After all we engineers are primarily employed to measure things.

Since MBAs rule and hold the purse strings, deliverables are essential to keeping a job even if they effectively worthless.

I sincerely believe that it would be useful to develop a measurement protocol for subwoofers that, like the way we use various applications to measure CPU performance, we present subwoofers with a variety of realistic use models designed not only to challenge their weaknesses but to obfuscate attempts to design them to exploit the measurement paradigm to artificially inflate performance ratings.

I wish that I had the resources to do this but I hope that I can inspire someone to develop this instead of simply bickering about the quarterback denied the touchdown because of the official's flag.

Seriously let's think about this objectively.

For years we had musclecar specs that were absurd compared to the actual performance.

Let's get together and try to develop a meaningful spec for speakers that represents actual performance in normal applications.

 

[CurtR]

The Kef KF92 is a terrible choice for 16Hz pipe organ, It's not capable of producing 16Hz at an audible/noticeable level. I would look at a pair of the biggest Rythmik subs that you could move on your own. Powersoundaudio has some good options as well that are lightweight for their bass capabilities. And while I don't think the G22 would be an ideal sub for pipe organ, one G22 will have more clean output at 20Hz than 8 KF92s. The KF92 could not even get a passing CEA-2010 score for 16Hz, that means no output with sufficiently low distortion to pass the test at 16Hz.

bo_knows measured the kf92 down to 15hz flat in his space. he posted graphs back around post 96 or so

 

[CurtR]

Seriously let's think about this objectively.

For years we had musclecar specs that were absurd compared to the actual performance.

Let's get together and try to develop a meaningful spec for speakers that represents actual performance in normal applications.

would have to keep it simple, but I'd say two specs are better than one: 1. the anechoic/outdoor test, and
2. in-room test, w parameters somehow agreed upon for what constitutes "typical," for our purposes "standard," room application ... ? that'd have to be defined.

Some of each is already done, in review spaces, but not always as a standard way of reporting. Looking through this thread, we see examples being put forth of both tests, some w graphs and room descriptions, even pictures, pretty cool. But as far as I know, there isn't any yet agreed upon formal in-room test spec standard method.

 

[JimA84]

To sound as loud as 55dB in the midrange you need about 105dB at 20Hz and bear in mind that almost all music has a spectrum that is tilted down as frequency increases so you'll need even more sub bass headroom.

Most music and even movie soundtracks sound quite good on a pair of compact active studio monitors like Adam Audio, Genelec or even the older Samson Rubicon 5a ribbon monitors which had little response below 59 Hz.

The AR-3a only really went to around 40 Hz but it was considered extremely accurate.

The main reason to have a subwoofer is if you truly want that last octave or so, but most music other than pipe organ, large drums or a few other things has very little content below about 40 Hz, and most musical instrument amplifiers have little response below that frequency, even bass guitar amplifiers.

Some movie soundtracks deliberately contain absurd sounds as low as 10 Hz, likely largely just because they can.

Movies like Grand Prix or The Final Countdown sound quite impressive at high volume on compact active monitors, even reproducing the sounds of a H-16 BRM Formula 1 engine or a Grumman F-14 Tomcat at full throttle.

Of course if you want Godzilla stomping cars into the pavement you may need a subwoofer. Or two.

So it's really a matter of whether that low frequency content is important for your preferred listening experience.

I would like a subwoofer that can reproduce a 16 Hz pipe organ but I have often lived with speakers like the Samson Rubicon 5a ribbons that only went to 59 Hz and had a brickwall filter that literally eradicated anything below 40 Hz.

As an aside, I find the present Internet meme of Dunning-Kruger amusing because it's not only typically completely misapplied, it is also reminiscent of the Peter Principle from 1969.

To really get this one should study Marshall McLuhan, particularly his 1964 book, "Understanding Media."

Tom Wolfe quoted MBAs fearfully asking: "What if he's right?"

 

[JimA84]

would have to keep it simple, but I'd say two specs are better than one: 1. the anechoic/outdoor test, and
2. in-room test, w parameters somehow agreed upon for what constitutes "typical," for our purposes "standard," room application ... ? that'd have to be defined.

Some of each is already done, in review spaces, but not always as a standard way of reporting. Looking through this thread, we see examples being put forth of both tests, some w graphs and room descriptions, even pictures, pretty cool. But as far as I know, there isn't any yet agreed upon formal in-room test spec standard method.

Actually Harman Audio's research paper on multiple subwoofers is quite interesting:

https://www.harman.com/documents/multsubs_0.pdf

 

[sigbergaudio]

like "a .50 cal is clearly superior" vs. a 9mm, but it rather depends on the application.

Not sure how this relates to my comment, but if it is a general comment to the discussion, I can understand what you mean.

 

[sigbergaudio]

Well, the FBI decided to go with the Glock craze with 9mm with bigger magazines until they got slaughtered in a gunfight against a drug cartel in Miami.

I'm afraid I don't know enough about guns to follow your metaphor and understand how it relates to our subwoofer discussion.

 

[Vacceo]

Most music and even movie soundtracks sound quite good on a pair of compact active studio monitors like Adam Audio, Genelec or even the older Samson Rubicon 5a ribbon monitors which had little response below 59 Hz.

The AR-3a only really went to around 40 Hz but it was considered extremely accurate.

The main reason to have a subwoofer is if you truly want that last octave or so, but most music other than pipe organ, large drums or a few other things has very little content below about 40 Hz, and most musical instrument amplifiers have little response below that frequency, even bass guitar amplifiers.

Some movie soundtracks deliberately contain absurd sounds as low as 10 Hz, likely largely just because they can.

Movies like Grand Prix or The Final Countdown sound quite impressive at high volume on compact active monitors, even reproducing the sounds of a H-16 BRM Formula 1 engine or a Grumman F-14 Tomcat at full throttle.

Of course if you want Godzilla stomping cars into the pavement you may need a subwoofer. Or two.

So it's really a matter of whether that low frequency content is important for your preferred listening experience.

I would like a subwoofer that can reproduce a 16 Hz pipe organ but I have often lived with speakers like the Samson Rubicon 5a ribbons that only went to 59 Hz and had a brickwall filter that literally eradicated anything below 40 Hz.

As an aside, I find the present Internet meme of Dunning-Kruger amusing because it's not only typically completely misapplied, it is also reminiscent of the Peter Principle from 1969.

To really get this one should study Marshall McLuhan, particularly his 1964 book, "Understanding Media."

Tom Wolfe quoted MBAs fearfully asking: "What if he's right?"

I think very low frequencies are part of what the user wants to get. There are genres such as techno or industrial that have a lot going on in the lower frequencies, so 20 to 30 hz is the bread and butter for the listener.

Infrasonics are very common in horror films, so a spectator would also want those stomach aches too. Gamers who want to listen beyond headphones will want that experience too.

Ideally a subwoofer, or several, should be able to reproduce any content you play no matter what; but realistically, it makes sense to invest on something that you will use often. That is, no need to spend crazy on infrasonic-capable monsters if they will just play Edge of Tomorrow-like content once every couple months.

From my own experience, I can confirm something as nimble as a KC62 does play infrasonics. However, it is set very close to the listening position, the room is quite small (a bit less than 10 square meters) and it is not very loud. If the KC92 can do the same in a bigger room, I will not complain. Price-wise, that's a different story.

 

[JimA84]

bo_knows measured the kf92 down to 15hz flat in his space. he posted graphs back around post 96 or so

This is my point. I've seen several credible members post measurements of the KF92 that back up the manufacturer's claims.

 

[waynel]

Take a look at this table that I extracted from Sweetchaos's spreadsheet. I filtered for small sealed subs (less than 2.4 cubic feet.

Manufacturer (sorted by, first)	Model (sorted by, second)		Converted to USD	20 hz	25 hz	31.5 hz	40 hz	50 hz	63 hz	80 hz	100 hz	125 hz	Weight (lb)	H (in)	W (in)	D (in)	Volume (ft^3)
Arendal	1961 Subwoofer 1S		1000	100.7	101.2	105.8	110.1	113.7	115.7	116	115.5	115.2	44.1	16.3	12.4	16.3	1.9
SVS	SB-3000		1100	96.6	101.7	107.8	114.6	118.7	120.7	120.9	120.8	120.7	54.5	15.6	15.2	15.7	2.2
JL Audio	E110		1900	96.3	101.6	107.2	111.7	115.2	116.4	116	114.8	114.2	52.7	14.2	13.5	16.5	1.8
Sigberg Audio	10D		3860	96	101	106.2	112.6	116.3	119.4	119	119.3	118.4	59.5	14.6	14.2	16.1	1.9
MartinLogan	Dynamo 1100X		1258	95.9	100.2	106.5	111.4	115.1	118.7	120.7	121.3	120.7	46	17.1	15	15.6	2.3
Starke Sound	SW12		670	93.5	101.2	106.1	112.8	115.6	114.2	113.7	114	112.1	39.5	15.7	14.9	16.7	2.3
Kef	Kube 10B		800	93.4	93.5	100.7	103.9	107.1	109.9	111.1			38.4	14.6	13.9	14.6	1.7
Sigberg Audio	INKOGNITO 12		3280	92	98	104	112.5	114	115	116			10	21.3	25.6	6.7	2.1
SVS	SB-1000 PRO		600	91	97.7	104.2	109.1	114.5	116.7	115.2	113.3	111.5	26	13.5	13	14.8	1.5
SVS	SB-1000		500	89.5	97.1	101.4	105.9	112.1	112.6	110.5			27	13.5	13	14	1.4
BK Electronics	XLS200-DF MK2		480	89.3	94.6	99.4	103.1	105.4	106.9	107.5			38.6	14	11.4	13.4	1.2
Sigberg Audio	INKOGNITO 10		2894	89	96	102	108	109	112	113			44.1	21.3	25.6	6.1	1.9
PSB Speakers	SubSeries 250		592	86.5	90.7	96.2	100.9	105	109.7	110.6			35.4	14.3	13.6	14.4	1.6
Kef	KF92		2000	86	91.6	95.4	101.1	103	104.4	106.3	107.2		44.1	13.9	13	14.2	1.5
Atlantic Technology	224SB		673	82.2	84.6	91.6	97.8	106.3	112.1	113.1			31	13.3	13.3	15.4	1.6
Monoprice	Monolith 8" THX Certified		350	72.9	86.1	93.2	96.9	99.3	100.7	101.6	101.9		19.8	12.6	13.5	12.6	1.2
Monoprice	SSW-10		135	70.8	79.2	90.8	99.7	104.7	112.4	116.1			30	7	25	15.7	1.6

Plotting shows some interesting results. Looks like the Arendal 1961 is particularly good for its price and its size and only weighs 44 lbs

 

[JimA84]

I appreciate your taking the time to do this. I had actually looked at that model.

I don't really know how to explain this, but it's really kind of an emotional thing that maybe doesn't make sense to a lot of people.

During my career I've focused on giving back to the community over personal enrichment.

So I was never as wealthy as some of my peers who relentlessly pursued personal wealth.

Also, in the mid 1970s I built some extremely high quality speakers for myself and friends with tolerances of about 0.2 mm. I hand built a high quality duplicate of a custom shop Fender Stratocaster guitar for another friend

So I appreciate some of the companies like Rythmik. Building a high quality handmade product at relatively low cost.

OTOH, my mother was a lifelong photographer of significant talent.

Around 1996 for her birthday I bought her a Leica camera.

I could have bought her a Nikon or Olympus for far less.

But I wanted her to have the pleasure of owning and using a genuine Leica.

I've never been the person who pays absurd premiums for a product brand.

Yet there are some things that are kind of intangible.

 

[sigbergaudio]

This is my point. I've seen several credible members post measurements of the KF92 that back up the manufacturer's claims.

I'm not sure anyone has challenged their claims specifically, although the specs are not very detailed. They claim 11hz -3dB, but they don't connect this information with their other specification (maximum spl: 110dB).

11hz -3dB is only true up to a point, where the subwoofer will lean out the response (increasing volume in higher frequencies but not down low). Looking at Erin's measurements the claimed 110dB is likely true in-room, but at 50-60hz, not 11hz (and not very far from the sub).

The KF92 will certainly reach your desired 16hz in-room, as measurements from other users have shown as well. The "problem" is that you cannot hear 16hz, you can only feel it. And to feel 16hz you have to play 16hz really loud, and significantly louder than a KF92 is capable of. This is probably true for every single sub in the chart posted by @waynel above.

I suspect you will perfectly happy with KF92, but it will not give you meaningful (as in you can hear and/or feel) output at 16hz. But I will argue you don't need that either. So there is a conflict between your stated requirements and KF92, but this is probably not because KF92 isn't the right sub for you, but because you are stating a requirement that you can likely live happily without fulfilling.

 

[Mnyb]

I’m considering the KC92 solely because of its room friendly size and look myself .
Probably at a >200% price hike to comparable options .

If you can live without the minor improvements the KC version has over the KF you can probably get discounts.

KC has the live saving always on option, many peeps have reported problems with kefs auto on functions on thier older subs.
Thye recently refreshed thier whole line up including the cube series