Why is Weak Bass recommended here?

[fpitas]

But I doubt that is part of the equation for calculating "with sub" preference scores. Or is it?

Good question.

 

[Steve Dallas]

(Sorry for the clickbait title)!

I've been looking back over the reviews of some of the most recommended speakers and one thing they seem to have in common is really weak bass.

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.

View attachment 278790

As a reminder, the manufacturer's specification is -6dB at 38 Hz which (if you are generous) could be achieved by that weird shelf in the bass response.
Preference rating for this is 6.5 or 8.1 with a sub.

Obviously small bookshelf speakers (like the Kef R3) will struggle to generate deep bass, so let's look at a tower type speaker (the Revel F35).

View attachment 278793

Again, the bass starts rolling off at about 100 Hz.
Manufacturer's spec is 55Hz, 46Hz, 35Hz (-3 dB, -6 dB, -10 dB).
Preference rating for this is 4.9 or 7.4 with a sub.


Now let's look at the Revel with the highest preference score currently listed in the review index (the F328Be):
View attachment 278794

Again, the bass starts rolling off at about 100 Hz.
Manufacturer's spec is 24Hz (-10dB); 26Hz (-6dB); 35Hz (-3dB).
Preference rating for this is 6.5 or 7.8 with a sub.


At this point I'm starting to wonder, is the Klippel actually able to measure the low bass frequencies properly?

But now let's look at this not recommended speaker (the B&W 805S):

View attachment 278796

Despite being a small bookshelf type speaker, the bass manages to extend down to about 60Hz before starting to roll off.
Manufacturer's spec is -6dB at 42Hz, -3dB at 49Hz.
Preference rating for this is 4.5 or 6.3 with a sub.

The low preference score and non recommendation for the 805S are due to the bumps in the frequency response. Such bumps could be caused, for example, by port resonances which possibly could have been reduced if the speaker wasn't tuned for such a deep response. So manufacturer's likely have to trade-off bass extension for smoothness of response.


Maybe it is an unrealistic hope, but I really don't want the bass to start rolling off until well below 80Hz (especially in floorstanding speakers) in order to have a flat response on which to impose the THX recommended 80Hz crossover.

The "with sub" preference scores are strongly biased toward speakers that don't have a deep bass response. (They assume that a perfect subwoofer will handle any low frequencies that the speaker can't manage). But if the bass roll-off of a speaker is higher, then it means the high frequency extension of the sub needs to reach further up - which is not necessarily the case and could be difficult to integrate.

Particularly in cases where people are planning to listen without subwoofers, I think a lot more emphasis should be given to bass extension.

Boundary reinforcement means in-room response extension is much better than the predicted response. The room and placement within it indictate much of the bass response of a given speaker.

Here is the KEF R3 in my room (F3 at 35Hz):

With a little DSP help, I can extend that down to 32Hz. That is low enough for the music I tend to enjoy:

And, here it is vs. PIR:

I would not call this weak bass and do not see a problem here.

 

[dfuller]

The in-room response estimation is only accurate above the room's Schroeder frequency.

Well, accurate-ish.

 

[RobL]

These are the sort of responses (or even deeper) that I'd hope to see from floorstanders.

They don’t estimate room gain (as has been noted). This is the response of my 8361A’s in my room:

-3dB @ 26hz

 

[-Matt-]

Boundary reinforcement means in-room response extension is much better than the predicted response. The room and placement within it indictate much of the bass response of a given speaker.

Here is the KEF R3 in my room (F3 at 35Hz):

With a little DSP help, I can extend that down to 32Hz. That is low enough for the music I tend to enjoy:

And, here it is vs. PIR:

I would not call this weak bass and do not see a problem here.

With DSP that looks pretty nice. Of course, I am already aware of the concept of boundary reinforcement.

The graphs in the OP make it look as though the only speaker able to give full signal right up to an 80Hz sub crossover, is the B&W 805s. (Even though I'm pretty sure the larger Revels should actually be able to give much better bass). (It makes it look like these wouldn't even be suitable as surround satellites)!


The "problem" for me is in trying to use the predicted in-room response data to compare different speakers.

How, in the current measurement scheme, is a speaker with superior bass extension to be recognised? The B&W 805S was criticised for being too bassy! How is this quantified within the preference score? Is it given sufficient weighting relative to the smoothness of higher frequencies?

If the theoretical boundary reinforcement can be calculated easily then it should be possible to do something like this...

Where the different colour curves to show the minimum bass response needed (in different sized rooms, small, medium, large m3) in order to produce an ideal 80Hz crossover to a sub.

Obviously there would be assumptions, like standardised distances between the speaker and boundary for each of the room size scenarios.

This would then show visually, that whilst Kef R3 might be fine in a smaller room, it might struggle in a larger one (for example).

 

[krabapple]

I think Harman recommends 120Hz max.

That is likely driven by recognition of the industry standard for LFE channel bandwidth (Dolby and DTS x.1 sources) : 120Hz

 

[fineMen]

Again my (beloved?) R3s. A nasty shelf they have. That's the best one can do if reinforcement from room modes and general room gain have to be expected. That holds true for nearly all domestic installations. But not so much for studios. You could recognize the pattern in the above quoted measurements.

May I ask if you were willing and enabled to do some own measurements? Do you ask on ground of speculations or direct experience? Anyway, in case the advice wasn't given yet, in order to squeze most out of the monetary investment (a) measurment equipment and (b) proficiency to use it is essential. Especially in the bass. Otherwise your ranking will come out way lower than anticipated ;-)

And again the R3, you kill me ;-) Nope, your pencil drawings don't fit. In my relatively large room the KEF R3s, as a pair, go full level down to 30 (!) Hz (-3dB at like 25Hz) with a perfect Harman tilt. No audible sacrifice in clarity up to 94dB peak level. Substitute of R3's bass with a sub was a bit inconclusive which to prefer. Really, it doesn't make sense to only swim dry (do you say that?), get yourself some meas/ equipment ... before you scrutinise my R3s

 

[delta76]

Of course. I even made a comment to this effect in the op.

The point is... If I made a speaker that only had a tweeter (no woofer at all) and somehow it had a nice smooth response but only above 3kHz. Then in theory this could get a very high "with sub" preference score. But good luck finding an ideal sub that you can use with a crossover frequency of 3kHz!

"With sub" preference score completely forgives vast failings in bass whilst strongly punishing small ripples at higher frequencies. Or perhaps I'm wrong. Does it specify an upper limit for the frequencies that can be contributed by the ideal sub?

Of course. I even made a comment to this effect in the op.

The point is... If I made a speaker that only had a tweeter (no woofer at all) and somehow it had a nice smooth response but only above 3kHz. Then in theory this could get a very high "with sub" preference score. But good luck finding an ideal sub that you can use with a crossover frequency of 3kHz!

"With sub" preference score completely forgives vast failings in bass whilst strongly punishing small ripples at higher frequencies. Or perhaps I'm wrong. Does it specify an upper limit for the frequencies that can be contributed by the ideal sub?

3khz is really extreme, if you consider that covers most of vocals. We are talking about realistic subwoofers here (up to 120hz)

 

[-Matt-]

Again my (beloved?) R3s. A nasty shelf they have. That's the best one can do if reinforcement from room modes and general room gain have to be expected. That holds true for nearly all domestic installations. But not so much for studios. You could recognize the pattern in the above quoted measurements.

May I ask if you were willing and enabled to do some own measurements? Do you ask on ground of speculations or direct experience? Anyway, in case the advice wasn't given yet, in order to squeze most out of the monetary investment (a) measurment equipment and (b) proficiency to use it is essential. Especially in the bass. Otherwise your ranking will come out way lower than anticipated ;-)

And again the R3, you kill me ;-) Nope, your pencil drawings don't fit. In my relatively large room the KEF R3s, as a pair, go full level down to 30 (!) Hz (-3dB at like 25Hz) with a perfect Harman tilt. No audible sacrifice in clarity up to 94dB peak level. Substitute of R3's bass with a sub was a bit inconclusive which to prefer. Really, it doesn't make sense to only swim dry (do you say that?), get yourself some meas/ equipment ... before you scrutinise my R3s

My beloved, I don't think you have grasped my meaning as intended! I'm not insulting your R3's. Surely I'd be banned for such heresy!

3khz is really extreme, if you consider that covers most of vocals. We are talking about realistic subwoofers here (up to 120hz)

I don't actually suggest such a speaker - I'm pointing out a potential failing of the "with sub" preference score system.


I'll try to ask the question another way... For a specific room size, and speaker to boundary scenario, what shape would the bass response (shown on the predicted in-room graph) have to take in order not to need any EQ and to integrate perfectly with an ideal sub crossed at 80Hz.

 

[fineMen]

My beloved, I don't think you have grasped my meaning as intended! I'm not insulting your R3's. Surely I'd be banned for such heresy!

Apologies acknowledged (just kidding)

For a specific room size, and speaker to boundary scenario, what shape would the bass response (shown on the predicted in-room graph) have to take in order not to need any EQ and to integrate perfectly with an ideal sub crossed at 80Hz.

I think the question is ill posed. The room is a random piece in the equation. Some folks sit on their sofa which (in Europe) often sits at the wall, other bend their knees just in front of their speakers. To whom would you give the bass they crave for? No way out, measurement equipment and equalizer, otherwise sub-par non-hifi sound. Let's propagate this idea and offer the according service to the many ignorants out there! We could, as experts, charge say some proletarian 1k$ per hour, two treatments needed the least, and winter/summer adjustments just as a refresher with some discount ... you know, the 'real' hifi can't be had for cheap, no, no.

 

[-Matt-]

I think the question is ill posed. The room is a random piece in the equation.

Which is why I suggested three reference scenarios.

The point is just to put some reference curves onto the estimated in-room response chart, so that people can easily estimate (from the measurements published in the reviews) whether a speaker has adequate bass extension. (I.e. Before they have the speakers - so measurement equipment wouldn't be much help).

Apparently there are additional problems with the validity of those measurements.


Currently I'd be a potental buyer of the larger Kef R series speakers but the bass response shown on these graphs is extremely off-putting (even though I'd have multiple subs).


I'm wondering if between us we can come up with a way that the measurent data could be presented that might make it easier to estimate whether (or not) a speaker would have adequate bass.

Since it is such a common use case I'm proposing that the minimum bass response needed for integration with a perfect sub crossed at 80Hz could be used as a benchmark. (With a few different curves shown to account for variation is room size).

 

[krabapple]

Bass response in graphs are less 'off putting' if the problem is hills rather than valleys. Hills can be tamed with DSP*. Valleys not so much.

(*assuming you don't eschew DSP/digital entirely)

 

[-Matt-]

Bass response in graphs are less 'off putting' if the problem is hills rather than valleys. Hills can be tamed with DSP*. Valleys not so much.

(*assuming you don't eschew DSP/digital entirely)

Agreed, I'm very happy to use EQ/DSP.

From the predicted in room measurements shown in the OP, can you easily see which speakers will have an excess of bass extension beyond an 80Hz sub crossover?
I cannot.

 

[fineMen]

Which is why I suggested three reference scenarios.
...

It's random--as to mention room size, position of speaker, listenr(s). So, alas, reference doesn't make any sense. But measurement and e/q do. Shelling out thousends on gear, upusing day after day with discussing things, but giving the Uncle Scrooge when it comes to 90$ for a mike and some real proficiency?

Currently I'd be a potental buyer of the larger Kef R series speakers but the bass response shown on these graphs is extremely off-putting (even though I'd have multiple subs).

I personally find the KEF R3 quite aesthetic as a piece of engineering. Yep, to kind of see the minds working on it (in hindsight) can be a bizarre pleasure for the enlightened. And KEF is a firm which I follow long time since the 70s. But I don't advocate them.

It is only so, room gain exists, Doppler distortion exists, people don't believe, KEF addresses the topics anyway. What shall I say? One hint nevertheless: if you have subs already, what is the use in buying the bigger model? Is it the same coax, yes, and reportedly it is crossed over lower which in my book doesn't do it a favour with even higher expectations for distortion free volume.

 

[Spocko]

Maybe the sketched curve could show the theoretically ideal rolled off bass response which would be needed to match the THX 80Hz crossover? Anything that extends below this would just be gravy!

I believe THX prefers a hard drop off at the subwoofer crossover point which is why THX monitors like Perlisten are sealed rather than ported as they are designed with subwoofers in mind.

 

[-Matt-]

It's random--as to mention room size, position of speaker, listenr(s). So, alas, reference doesn't make any sense. But measurement and e/q do. Shelling out thousends on gear, upusing day after day with discussing things, but giving the Uncle Scrooge when it comes to 90$ for a mike and some real proficiency?

This is really very strange the way that you persistently demand that buy a measurement microphone. Particularly as I already have such and have posted several sets of my own measurements here already. Most odd? Are you AI?

It is rather incongruous because I'm not talking about trying to optimise speaker performance in a particular room. I'm talking more generally about the way speaker measurements are made and presented here. And furthermore what should be the optimal design goals for a speaker with respect to bass extension.

I think we have a communication incompatibility.

 

[-Matt-]

I believe THX prefers a hard drop off at the subwoofer crossover point which is why THX monitors like Perlisten are sealed rather than ported as they are designed with subwoofers in mind.

Ok, and I'd like to know how a speaker's predicted in room response would need to look, in order to best compliment this.

 

[abdo123]

Ok, and I'd like to know how a speaker's predicted in room response would need to look, in order to best compliment this.

Just use Audessy or any room correction you have to correct the response back to anechoic levels.

 

[Spocko]

The "with sub" preference scores are strongly biased toward speakers that don't have a deep bass response. (They assume that a perfect subwoofer will handle any low frequencies that the speaker can't manage). But if the bass roll-off of a speaker is higher, then it means the high frequency extension of the sub needs to reach further up - which is not necessarily the case and could be difficult to integrate.

Particularly in cases where people are planning to listen without subwoofers, I think a lot more emphasis should be given to bass extension.

You bring up a few points that should also be addressed:

1. Good speakers with 6.5" woofers should easily roll-off at 100Hz with headroom to spare (or wherever your room's transition frequency). Reasonably priced subwoofers from Monoprice (THX series) or SVS can crossover at 100hz with zero problems, so integration should not be a problem as long as you crossover below your room's transition frequency to avoid subwoofer localization.
2. People planning to listen full range without subwoofers face far more obstacles if their speakers are capable of full range down to 25Hz.
   • Below the room's transition frequency, there is no way to correct for nulls caused by the placement of the speakers, unlike subwoofers that you can move around to optimize for your MLP and mitigate for such nulls. These deep nulls have a far greater affect on SQ than the in-room response curves that do not take these room-related nulls into account.
   • Powerful amplifiers are required but most people planning to listen subwoofer free "full range" do not realize this. For full range speakers to generate the necessary SPL for accuracy down to 35 Hz that matches monitor+subwoofer setup requires careful amplifier matching to ensure you have enough power.

I completely understand the point of your concern, but I think once people begin to troubleshoot for subwoofer free listening, it becomes a rabbit hole of cascading room correction issues that are far more destructive than the theoretical shortcomings of the frequency response curves.

 

[fineMen]

This is really very strange the way that you persistently demand that buy a measurement microphone. Particularly as I already have such and have posted several sets of my own measurements here already. Most odd? Are you AI?

It is rather incongruous because I'm not talking about trying to optimise speaker performance in a particular room. I'm talking more generally about the way speaker measurements are made and presented here. And furthermore what should be the optimal design goals for a speaker with respect to bass extension.

I think we have a communication incompatibility.

I'm NI. I only wonder why the roll off bothers you in the given case that you have subs already, and also means to integrate them properly.

So, you attempt to address a general problem with a general solution. You want to generalize room sizes, seating positions, speaker positions, room treatments, the interior decor and all.

As I already said, a shelf is quite optimal. One could only ask--narurally, where to start it in frequency and how deep it should dive.

My comment on that: it will (almost) never fit! I kind of contradict your attempt. So be it.

My solution: advertise room equalization, supported by a mircrophone and a minimum of competence on the side of the consumer.

Very much more interest shall be focused on how the deep bass also limits midrange quality, especially with the all too common 2-ways. It is not all about extension.