Why is Weak Bass recommended here?

[Prana Ferox]

Looking at it one way:
- Making a speaker flat or especially sloping up to 20 hz runs into Hofmann's Iron Law; the speaker tends to be large and require a ton of power. Drivers are likely to require large xMax which drives compromises elsewhere in the frequency response (or requires them to essentially become built in subs for multiway uppers.)
- These are somewhere between unacceptable and impossible characteristics for all but the biggest floorstanders. Certainly not feasible for routine bookshelves
- Thus the bass response claims of most speaker manufacturers are bunk
- They can get away with this because room response and gain play such hell with the lowend FR regardless

Alternately:
- Room response can be hard to predict or correct for, for the vast majority of consumers
- Room gain can be dramatic and generally a hot signal (peaks) is more offensive than a cold one (valleys)
- At the very least a 'flat' speaker would sound crappy in at least 50% of rooms and placements, where it would be boosted - but actually with standing waves it's more likely to have some frequencies noticeably boosted, potentially offensively, in almost all rooms and placements
- Therefore to avoid offensive sound it is best to roll off the bass some degree to tame the worst potential room gains... which are heavily dependent on placements that will vary by speaker design (a sane person doesn't put a floorstander on a bookshelf etc.) As such, at best, different speaker form factors would have different 'ideal' curves, but not with any kind of uniformity that you could say "This is a 6.5" bookshelf, it should follow this curve."

This is further complicated by the Fletcher-Munson curves where a speaker that is tuned to be more 'bass-shy' at lower volumes will sound better when cranked (until it runs out of steam) and a flatter one with the volume low will sound boomy when loud.

 

[sigbergaudio]

- Thus the bass response claims of most speaker manufacturers are bunk

I don't think that is necessarily true, many speakers (even bookshelves) are indeed tuned quite low. We saw earlier in this thread that this was the case with the Kef R3, and the stated specifications are correct. As a consequence, they cannot play very loud before the woofer gives up / starts distorting. This is a design compromise.

 

[Kvalsvoll]

High passing the speakers and using a subwoofer (which you can then adjust in volume and potentially eq) is also a good solution to better match the bass output to the room. Then you are less dependent on finding a speaker which happen to match the room with regards to bass tuning.

Too easy, and it actually works. Or so I thought, but, I was wrong.

The better solutions for a manufacturer is of course a customer who seeks to solve the problem in an endless process of continuous purchase of new expensive speakers. Perhaps throw in a new power cord now and then. Or a DAC with really tight, precise bass. Just make sure all amplifiers have a clean signal path with no eq/dsp. This will work, at least until the customer runs out of money ("..will eventually run out of other people's money.").

 

[fineMen]

I don't think that is necessarily true, many speakers (even bookshelves) are indeed tuned quite low. We saw earlier in this thread that this was the case with the Kef R3, and the stated specifications are correct. As a consequence, they cannot play very loud before the woofer gives up / starts distorting. This is a design compromise.

I'm not advocating KEF in any way. It's only so, that you discuss already well established techniques that the R3 uses as if they were specifically debatable for KEF / Rn.

Extended bass shelf (didn't read it): https://www.diyaudio.com/community/threads/extended-bass-shelf-versus-quasi-butterworth-5.362124/

As it comes to the output capabilities, I'm currently suffering from hyeracusis due to the R3's virtue to effortlessly, namely distortion free, deliver. That is in parts a benefit of the well designed drivers, but also comes with the quite reasonable deployment, ported, bass shelf, 3-way. The fool I am thought it would be ok to crank up until it distorts, let's test the limits ... and I fell over the cliff. In a 70sqm room with (very) high ceiling @3m listening distance using 50watts/ch max..

The problem here is, that the topic is discussed on unknown grounds, huge white landscapes on the map, if you will. And as far as I see the o/p didn't experiment yet despite having the necessary stuff at hand, and also despite the many incentives given.

To answer the underlying question: yes, buy the R3s, bass is way sufficient and with subs its perfect. No need to (let) plan the room integration any further. In Europe there's a sell out happening. For 500 each it's a steal. I gave up DIY after some decades, go figure!

 

[sigbergaudio]

@fineMen To be clear I have nothing against the Kef R3 specifically or Kef in general (quite the opposite). I'm just using it as an example since everyone else is in this thread. A compromise is not a bad thing, it is a choice that has to be made. There is nothing inherently wrong with the R3 or the design choices made as far as I can tell.

In my reply I was using the R3 as a positive example, a bookshelf speaker that does indeed play low frequencies, and have accurate specifications (as a reply to a claim that specifications were often wrong).

 

[Prana Ferox]

I don't think that is necessarily true, many speakers (even bookshelves) are indeed tuned quite low. We saw earlier in this thread that this was the case with the Kef R3, and the stated specifications are correct. As a consequence, they cannot play very loud before the woofer gives up / starts distorting. This is a design compromise.

Tuning low isn't the same thing as claiming presumably flat bass response down to what may actually be the -6db or -10db response point. And tuning low / an extended bass shelf in and of itself is a means of managing power handling for passive ported speakers, because the manufacturer can't assume the customer will use any bass management, and power handling evaporates for frequencies below Fs.

 

[sigbergaudio]

Tuning low isn't the same thing as claiming presumably flat bass response down to what may actually be the -6db or -10db response point. And tuning low / an extended bass shelf in and of itself is a means of managing power handling for passive ported speakers, because the manufacturer can't assume the customer will use any bass management, and power handling evaporates for frequencies below Fs.

I'm not sure where I said that tuning low was the same as claiming flat bass. That would be a strange thing to say.

I'm also not saying no one does things like that. Kef, as was the example here, do not. And my impression is that most actually specify -3/6/10dB.

 

[Mnyb]

The question I would like to point at is this .

You all seems to have reached a consensus that bass response in room is random and unpredictable.

Yet KEF seems to have the opinion that it is somewhat predictable hence their shelf that can’t be user tuned in lesser models ? Thier bet is that there is some net positive gain in most rooms ?

 

[YSC]

The question I would like to point at is this .

You all seems to have reached a consensus that bass response in room is random and unpredictable.

Yet KEF seems to have the opinion that it is somewhat predictable hence their shelf that can’t be user tuned in lesser models ? Thier bet is that there is some net positive gain in most rooms ?

I would say it’s unpredictable to where exactly are the room modes so you can’t pin point it and make it perfect, but in general ppl wont put speakers in the middle of a room and more often if not always, within 1m from walls, which unavoidably will create peaks and nulls with room modes, nulls can’t be fixed and are normally not annoying, but peaks could be reduced, it’s in my guess similar to the “wall mode” of the anechoic flat tuned actives like genelec, Neumann, kef, Kali etc. all have, a bass shelf to their own interpretation how normal room will create

 

[sigbergaudio]

The question I would like to point at is this .

You all seems to have reached a consensus that bass response in room is random and unpredictable.

Yet KEF seems to have the opinion that it is somewhat predictable hence their shelf that can’t be user tuned in lesser models ? Thier bet is that there is some net positive gain in most rooms ?

The general in-room curve isn't unpredictable for any given room, and the peaks and dips in any given room isn't unpredictable either per se, they're just different in every room - so you can't design a speaker to have the same bass response in any room. But you can design for intended bass extension and general bass level as sort of an average of the typical room you expect the speaker to be used in.

So in general pretty far from perfect, which is why DSP/EQ is preferrable in the bass region.

 

[abdo123]

As a consequence, they cannot play very loud before the woofer gives up / starts distorting. This is a design compromise.

What? Is this some sort of manufacturer bias or something?

the port is tuned at 40Hz, and any content below that in music is usually significantly lower in amplitude.

I've literally never heard any comment by any reviewer that the KEF R3 can't play loud.

I would understand this sort of comment for the LS50, but for the R3?

At approximately 4m listening distance, I found the max SPL to be about 95dB. Exceeding this resulted in an unpleasant sound for a variety of music. 95dB in-room at 4m is pretty loud and when you pair these speakers with a subwoofer, the max SPL is increased a bit more. - Erin

First the good news: the type of buzzing distortion I thought I heard with KEF Q100 was not there. It was replaced by very clear response together with strong deep bass when required. Power handling was now excellent as I could turn up the speaker as much as I needed and despite only one speaker playing. The sound was clean. - Amir

 

[sigbergaudio]

What? Is this some sort of manufacturer bias or something?

the port is tuned at 40Hz, and any content below that in music is usually significantly lower in amplitude.

I've literally never heard any comment by any reviewer that the KEF R3 can't play loud.

I would understand this sort of comment for the LS50, but for the R3?

Again as mentioned before I have nothing against either Kef or the R3, quite the opposite. It can obviously play at a perfectly adequate level for what it is. Based on Erin's review: "At approximately 4m listening distance, I found the max SPL to be about 95dB. Exceeding this resulted in an unpleasant sound for a variety of music."

To me personally, this is not loud in absolute terms. For many others this will be perfectly fine. I don't think anyone would expect a speaker the size of the R3 to play full range music extremely loud, that's just physics.

 

[abdo123]

Again as mentioned before I have nothing against either Kef or the R3, quite the opposite. It can obviously play at a perfectly adequate level for what it is. Based on Erin's review: "At approximately 4m listening distance, I found the max SPL to be about 95dB. Exceeding this resulted in an unpleasant sound for a variety of music."

To me personally, this is not loud in absolute terms. For many others this will be perfectly fine. I don't think anyone would expect a speaker the size of the R3 to play full range music extremely loud, that's just physics.

Please keep in mind in the future that forum rules asks manufacturers to be extra careful when posting about their competitors.

• We expect you to post with highest levels of professionalism. You are representing an industry and it is important that this be done with utmost politeness and respect for the membership. Be especially careful when you post about your competitors.

 

[YSC]

Please keep in mind in the future that forum rules asks manufacturers to be extra careful when posting about their competitors.

but to be fair I don't think sigbergaudio have said inappropiately, it's just kind of using the early referenced speaker (R3) by the OP and discuss why and how the design choice might be, which makes perfect sense to me on this topic

 

[sigbergaudio]

Please keep in mind in the future that forum rules asks manufacturers to be extra careful when posting about their competitors.

Yes, my apologies. Again it was not meant as a negative characteristics, and I have repeated numerous times that I have great respect for Kef. I will be even more careful in the future.

 

[-Matt-]

This thread seems to have run its course, so as the OP I hope I'm permitted to briefly summarise...

First I'd like to highlight two points made in the first post.

(Sorry for the clickbait title)!

Saying that "Weak Bass" is recommended here is obviously controversial. I don't necessarily believe this; to some extent I've been playing devil's advocate in order to stimulate the discussion.

Perhaps I'm making an incorrect assumption, but I'd expect that in the ideal world we would aim for the in-room response to have a gentle downward slope which carries on all the way to 20Hz (dashed blue line below). Furthermore, when it rolls-off, it is better if it drops sharply so that it doesn't put bumps into the region that potentially overlaps with the sub.

Here is a graphical representation of my incorrect assumption:

I assumed that in an ideal world, for a "full range" speaker, you would want the bass response to extend all the way down to 20Hz before rolling off.

To me, it looked as though the red shaded region was missing (which I initially termed "weak bass"). It was therefore puzzling to me that several speakers with this type of rolled-off bass response should be highly recommended here.

Recognising that we should have lower expectations for bookshelf speakers I stated...

Obviously small bookshelf speakers (like the Kef R3) will struggle to generate deep bass

I'd like to state categorically that I don't have anything at all against Kef or the R3 - they were simply chosen as an interesting example that exhibited this rolled-off bass response. The choice of the R3 as an example has apparently upset some owners (for which I apologise), however, it is likely that whichever speaker I chose to show would have upset its owners. Many owners of the R3 responded that they get adequate bass from their speakers due to room reinforcement (which is reassuring as I would consider purchasing from this range of speakers).


At the time of the OP I was even more surprised that the same type of rolled-off bass response was shown by several recommended floorstanding speakers (some from Revel were shown). This was more surprising to me because my expectation was that a floorstanding speaker should be able to play "full range" - which I considered to mean that it should have an approximately flat frequency response pretty much down to 20Hz (or at least 40 or so Hz).

@DJBonoBobo reminded us that some active monitor speakers had been tested and produced a response that is much closer to my expectation for "full range" speakers:

As an aside, we briefly discussed the preference score - eventually learning that the "with sub" score completely ignores the frequency response below 100Hz. (Below 100Hz, the standard preference score only considers a single value (the -6dB point for bass extension). This means that a speaker with a shelved bass response which slopes downward from 100Hz to 40Hz then drops sharply (hitting -6dB at 38Hz) could score exactly the same as a speaker that maintains a flat response all the way down to 40Hz before dropping sharply (also hitting -6dB at 38Hz).


Many others made the same point but @amirm put it most succinctly...

The room dominates the response in bass region, not the speaker. You can't make any judgements about that region from measurements. The PIR gives clues as to tonal balance, not exact frequency response in a real room. It represents a room with no room modes.

@YSC (and others) helped me to understand that different speakers may be designed with different assumptions about the room. (I.e. active monitors may be designed with a treated studio in mind where bass absorption is in place to prevent excessive room gain, whilst home speakers may be designed with the assumption that they will receive some bass reinforcement from the room and that, in any case, it is better to err towards more attenuated bass, to avoid boomy bass resonances in untreated rooms).

Pasives usually have a more gently rolled off bass below 100hz, which put in most realistic homes (highly likely pretty close to corners or front wall at least) would have a more balanced bass response slope, where actives like Genelec and Neumann usually have a extended bass before a sharp roll off, reason is likely that for passive users, the design need to balance out by some tricks in most homes expecting the customer not using active DSP or so to tame the room modes, and for those who heavily treat their rooms, more than likely they will do subwoofer integration to fill in the nulls also, while for actives they would assume more customers have a treated studio, but also taking advantage of the active design, more often leave some "room mode" switches to counter the boomy bass in normal room with excessive boundary gain

At this point I became interested in what could be considered the theoretically optimum choice for the bass roll-off shape - could a standardised target perhaps be designed? @sigbergaudio offered some valuable input to the discussion, but ultimately the optimum shape of the bass roll-off is highly room dependent and since it cannot be known a priori by the speaker designer, or solved in general for all rooms, it becomes a design decision and a matter of preference. (However Kef do provide tuning options for their reference series speakers, as discussed in the video posted by @KMO above).


So in conclusion, it isn't that "weak bass" is recommended here.

The assumption made in the OP was that the ideal predicted in-room response would extended linearly down to 20Hz before dropping off sharply. That assumption becomes incorrect in rooms that offer significant bass reinforcement, where a rolled off bass response on the PIR chart may still allow full range bass to be achieved in real-world, in-room measurements.

Furthermore, in cases where a subwoofer will be integrated using DSP the precise shape of the bass roll-off and its extension is largely irrelevant (provided that there isn't a gap between the top of the sub response and bottom of the speaker's range).

Thanks to everyone who contributed to the discussion (too many to mention all individually), I've learned a lot along the way.

 

[Steve Dallas]

Potentially not yet mentioned is the fact that only very expensive speakers are capable of reaching 20Hz at F3, and they are typically very large. That is, in part, what makes the economics of subwoofers work so well.

This chart is a little bit apple-y, orange-y, but as part of one of my Revel F206 speaker setup sessions, I compared Audyssey XT32 room correction (limited to 1000Hz) to Dirac room correction (limited to 600Hz). XT32 included dual subs, whereas Dirac included no subs. As you can see, F3 for XT32 is below 20Hz, and F3 for Dirac is ~33Hz. The subs were $1000 for the pair. Buying speakers that would go that low would cost at least $10,000 if not $20,000+.

So, to answer your question as to why speakers that do not extend to 20 or 30Hz anechoic, recommending only those speakers would mean recommending almost no speakers. And you know the rest about anechoic bass measurements not telling the whole story.

Good thread.

 

[Alice of Old Vincennes]

Kef's slight bass rollofs are likely intentional and because they're designed for European construction which tends to be denser than in North America, so you get more boundary gain. They're actually trying to make the bass flat instead of overwhelming. They offer different physical ports in the Reference series to allow customizing that.

Realistically speaking you absolutely must have the ability to EQ in order to get correct bass in any setup, so you can just EQ them flat to 40hz if they're not in your room.



Huh? The 8361A is probably the most strongly recommended speaker on the site and it has incredible bass for its size. The KH150 is another recent review and it also has incredibly good bass for its size.

Bass is a very important component of the preference score, so if a speaker has a poor score despite having good bass then it's probably quite bad in other attributes.



"with sub" scores assume you have a 100% perfectly integrated subwoofer that goes perfectly flat to 20hz or below and that the bass response of the speaker is sufficient to create such a perfect crossover, the crossover frequency being rendered irrelevant.

Good luck with integration.

 

[KMO]

We have just got another answer to this question from a KEF visitor to the forum - the longer port length that gives this bass roll-off also helps with transient response:

KEF R Series with MAT white paper

Ref 1 Meta:

audiosciencereview.com

 

[AnalogSteph]

I would like to add one specific point here:
A floorstander is invariably close to at least one boundary - the floor (duh). You will never get an accurate (practically relevant / comparable) deep bass response out of the Klippel if it assumes the speaker to be floating in free space. Same problem we have with measuring in-ceiling speakers accurately (those have it even worse).

As for why a bookshelf like the R3 would have a shelved bass response, the answer is likely to be somewhere between boundary reinforcement encountered in typical setups and level handling considerations, as previously mentioned. There is only so much a 6.5" woofer can do, more so when it isn't quite on the level of a Purifi - you can only make up for surface area with excursion if a given displacement is required, and excursion for a given level goes up rapidly as frequency goes down. Keep in mind that hi-fi speakers are expected to perform at distances that would be considered "mid-field" in the studio realm. That's much different from a pair sitting on your PC desk.