Revel M106 Bookshelf Speaker Review

[KaiserSoze]

Agree myself bought some KEF Q150 couple of months ago to canabalize the driver array for diy fun and lol i haven't yet had time and energy to listen how they sound stock, for me its okay Amir try stop AJ relative in relation to what he heard in his sessions so far for coxials but pretty sure myself can get that Q150 array combined some woofer and unlimited DSP engine at 192kHz to perform over avarage or maybe more.

I've had similar thoughts with respect to the Elac bookshelf with concentric. You presumably like the KEF concentric better than the Elac concentric, yes? What are the specific reasons?

 

[KaiserSoze]

Nope that's not how it works. You see the HD generated by the frequency in the graph. And the level (SPL) of that particular frequency you see in the 'axial magnitude frequency response graph'.
So for instance if you select 5v6 in the 'axial magnitude frequency response graph' you'll see that that voltage gives 102dB SPL at 2kHz, but only 91dB SPL at 500Hz. Then you look at the 'HD frequency response (315 mm distance)' graph and select 5v6 there and you'll see the HD generated at which frequency. But it means that if you look at the HD generated at 500Hz you're looking at the HD generated by 500Hz at 91dB SPL, and if you're looking at 2kHz in the same graph still at 5v6 you're looking at the HD generated by 2kHz at 102dB.
edit: in other words, the 'axial magnitude frequency response graph' is the fundamental for the 'HD frequency response (315 mm distance)' graph.
edit2: and if you see in the 'HD frequency response (315 mm distance)' for instance H2 at 500Hz at 5v6 at -44dB that means that this H2 product will actuall fall on 1kHz (500Hz * 2) with an amplitude of 91dB - 44dB = 47dB SPL.

I'm going to have to study this some more, maybe tomorrow.

 

[KaiserSoze]

Yes, I’m German. Are your stereotype believes now satisfied?
Maybe you can also help me what was so humorous about your first post? I’m eager to learn humor. Ha, ha! Or should it be three times? Germans don’t know... Ha, ha, ha!

I don't want to further any stereotypes, but a fellow I once worked with had a funny thing he would do sometimes to poke fun at a German fellow who was the top technical guy at one of the major satellite TV providers. The guy trying to be funny (it was a little funny actually) would speak in that bad accent that is supposed to mimic Germans and then say, "Start relaxation, NOW!" Then he would straighten out his legs and make himself all stiff as if this was a German person's idea of relaxing.

 

[JustIntonation]

I realized afterward that I muddled that. Manifestly, making the baffle wide moves the 1st peak of the diffraction ripple lower in frequency. As such the larger the radius of the round-off relative to the width the baffle the better the effect will be, the ideal being a cylinder with just enough flat region at the face to mount the drivers. For a driver mounted equidistant from both edges the 1st peak will occur at wavelength matching the baffle width. For a driver mount 2/3 of the way from the further edge, that distance will account for 180 degrees (the other 180 degrees is due to the 180 degree phase shift in the "soft" reflection), which means that 2/3 of the baffle width will equal 1/2 wavelength, and that the wavelength will equal 4/3 of the baffle width. For full width equal to 54 cm, if the affected driver is mounted at the midpoint the 1st peak will occur at 635 Hz. If the driver is mounted 2/3 of the way from the further edge (so that the harmonically related peaks occurring higher in frequency than the 1st peak will line up with the dips, i.e., with the frequencies where the wave coming off the edge is out of phase with the direct wave), the 1st peak will occur at 476 Hz. Given the low crossover point you indicated, the affected driver will be the midrange. Since the round-off will just barely be effective at these frequencies, the implication is that the midrange and tweeter should be placed off-center, such that the distance from one edge is twice greater than the distance from the other edge.

I've done this simple analysis a number of times before, and it always comes out this way. This was Linkwitz's point about trying to using rounded edges to overcome the diffraction ripple. In order for it to work, the enclosure pretty much needs to be a cylinder, i.e., the round-off radius has to be not much less than half the baffle width. When this is the case the diffraction ripple is avoided but of course the overall step remains. And to analyze the effect of the step in any meaningful way you have to make assumptions about the speaker placement, especially the distance from the baffle to the wall behind the speaker. The reflection from the wall is sort of the inverse of the baffle step with diffraction ripple. At very low frequency the wall reflection is in phase with the wave coming directly from the driver (which is why it doesn't make sense to try for 6 dB of baffle step correction, contrary to what a lot of hobbyists seem to believe). As the wavelength shortens the reflection from the wall becomes increasingly out of phase with the wave coming directly from the driver, until eventually it is 180 degrees out of phase and a dip occurs in the sound we hear.

An obvious question is whether it is possible to force the frequency where this dip occurs to line up with the first peak in the diffraction ripple. It turns out that the only solution to the equation you end up with is for the baffle to be mounted flush with the wall. This is an interesting exercise for the purpose of demonstrating that this is the only solution. The dip will occur when the total distance travelled by the wave, from the center of the driver to the edge of the baffle, then to the wall, then to the listener, is greater by one-half wavelength than the direct distance from the driver to the listener. For a driver mounted equidistant from both edges, the wavelength for the dip will be equal to the baffle width plus 4x the distance from the baffle edge to the wall. The wavelength of the first peak in the diffraction ripple will be equal to the baffle width, for a driver mounted equidistant from both edges. Thus, the dip will always occur at wavelength greater than the wavelength for the first peak in the diffraction ripple, the difference between the two wavelengths being equal to four times the distance from the baffle edge to the wall. The more closely the speaker is placed to the wall behind it, the more closely the dip will line up with the first peak in the diffraction ripple. If the speaker is mounted flush with the wall there is no baffle step and no diffraction ripple. Of course there is a popular notion that a speaker is best placed out away from the wall, but notwithstanding the popularity of this notion, I have personally not ever encountered an explanation that makes sense. If in fact a speaker sounds better when placed further from the wall, the reason is most likely that the speaker has a poor off-axis response which is rendered less obvious by moving the speaker out away from the wall.

Yes what you write is true except that the first peak on top of the baffle step will still be reduced by the roundover. What's left is only 1dB to 1.5dB of a very smooth hump (depending on diffraction modelling software used) and there is really no ripple left above that.
Indeed the mid+tweeter are off-center in my design. The main benefits are that it's slightly more balanced to EQ flat on-axis relative to the off-axis, that one has a slightly different off-axis in the mids to the left and right therefore can "tune" a little bit either a side reflection or for instance not do a toe-in and still have the direct sound be completely flat in fr at the listening position (other than the very top trebble) when placing the mid+tweeter on the outside, and lastly it simply allows more placement options. There is no negative effect of the offset to the ear as the woofer will be crossed at probably 180Hz.

As for flushmounting yes that's allways the best option regarding diffraction and baffle step Though I think my speaker comes a close second, the single diffraction remaining is almost irrelevant, the baffle step is still 6dB ofcourse, though I think with this design it occurs in the best region giving a rising bass in the off-axis (and that this is a main reason why wider baffle speakers often sound subjectively better and bigger as the baffle step doesn't fall mostly in the mids like with narrow speakers).
Furthermore the design is only 25cm deep which allows the speaker to be placed against the frontwall with for instance 5-10cm of rigid fibreglass behind it (though absorption behind the speaker is much less needed than with other speakers as the first cancellation would occur above the baffle step in this placement) and it'll behave very well (including when not giving toe-in due to the roundover and off-center mid+tweeter), almost like a flush mounted speaker (after room / boundary compensation EQ which is included in the Fusion plate DSP).

 

[BYRTT]

I've had similar thoughts with respect to the Elac bookshelf with concentric. You presumably like the KEF concentric better than the Elac concentric, yes? What are the specific reasons?

Primary reason is Q150 is relative low cost but also that KEF is several generations down that road, in low cost series Q150 plus Q350 is relative new release and replaces Q100 plus Q300, from KEF Amir had analyzed LS50/Q100/R3/Q350 as seen below animation that toggle modeled baffle step and diffraction, it looks as KEF improved bit on port leak/noice from Q100 generation to Q350 generation noticed in the smoother directivity index and also it looks for low cost series epecially relative to R3 that diffraction dont get the same care so that is a point where diy can set in and improve filterwise and build a enclosure using big roundovers, myself had ordered Q150 before Amir released Q350 review so its too late now but think i could have lived with that Q350 performance and in it has bit more cone area then stroke would be little less than Q150 and that should be a logic good thing when it also have funchtion as a tweeter waveguide, so far plan is Q150 array get high passed 180-200Hz to a close distance 10 or 12 incher.

 

[richard12511]

I think 96db is too low for the distortion test, and we need any speaker that can handle it to do 105 or so. That just so happens to be the max where I'll listen to a whole song.

I agree. I would say distortion at 111db is probably a good starting point. Still that might not be loud enough for reference in most living room distances.

Unfortunately, that could damage many speakers tested so far, and I doubt Amir wants to do that. Very few(if any) speakers tested so far are capable of movie theater dynamics.

 

[richard12511]

If I could have found a deal on the F36 that would have been an option, but compared to what I paid for the M106's, a pair of F36's would have been about €1000-1200 more still.

Also, I would expect M106 + subs to outperform F36 with subs. If you're using subs, I think bookshelves will generally outperform towers for a given price.

 

[beefkabob]

Also, I would expect M106 + subs to outperform F36 with subs. If you're using subs, I think bookshelves will generally outperform towers for a given price.

Maybe if you have really good sub/speaker integration.
Maybe if you have speaker stands that are cheap.
Maybe depending on your SPL desires.

 

[Chromatischism]

From REW Help: "Psychoacoustic smoothing uses 1/3 octave below 100Hz, 1/6 octave above 1 kHz and varies from 1/3 octave to 1/6 octave between 100 Hz and 1 kHz. It also applies more weighting to peaks by using a cubic mean (cube root of the average of the cubed values) to produce a plot that more closely corresponds to the perceived frequency response."
cheers

I've wondered why we don't use it more. It seems most would disagree with the smoothing below 100 Hz, so that's probably it. I don't typically apply any smoothing there.

 

[Chromatischism]

Ah then your waveguide is working well >3kHz or you have some treatment
But no I don't have a good test for listening to crossover effects of your own speakers in your own room.

No treatments at all yet. Aside from the narrow cancellation right at 100 Hz from a width mode, which exists right down the center line of the room, this shows you can achieve flatness even in the bass region of a small room (1400 cubic feet) with good placement of speakers and seats.

 

[Chromatischism]

Also, I would expect M106 + subs to outperform F36 with subs. If you're using subs, I think bookshelves will generally outperform towers for a given price.

Why would that be? Towers provide greater SPL capability and built-in stabilization, for a cost.

Perhaps you meant that for the same money, you can get into a higher line of bookshelves. I would agree with that. It just depends on your priorities.

 

[KaiserSoze]

Yes what you write is true except that the first peak on top of the baffle step will still be reduced by the roundover. What's left is only 1dB to 1.5dB of a very smooth hump (depending on diffraction modelling software used) and there is really no ripple left above that.
Indeed the mid+tweeter are off-center in my design. The main benefits are that it's slightly more balanced to EQ flat on-axis relative to the off-axis, that one has a slightly different off-axis in the mids to the left and right therefore can "tune" a little bit either a side reflection or for instance not do a toe-in and still have the direct sound be completely flat in fr at the listening position (other than the very top trebble) when placing the mid+tweeter on the outside, and lastly it simply allows more placement options. There is no negative effect of the offset to the ear as the woofer will be crossed at probably 180Hz.

As for flushmounting yes that's allways the best option regarding diffraction and baffle step Though I think my speaker comes a close second, the single diffraction remaining is almost irrelevant, the baffle step is still 6dB ofcourse, though I think with this design it occurs in the best region giving a rising bass in the off-axis (and that this is a main reason why wider baffle speakers often sound subjectively better and bigger as the baffle step doesn't fall mostly in the mids like with narrow speakers).
Furthermore the design is only 25cm deep which allows the speaker to be placed against the frontwall with for instance 5-10cm of rigid fibreglass behind it (though absorption behind the speaker is much less needed than with other speakers as the first cancellation would occur above the baffle step in this placement) and it'll behave very well (including when not giving toe-in due to the roundover and off-center mid+tweeter), almost like a flush mounted speaker (after room / boundary compensation EQ which is included in the Fusion plate DSP).

Here's a link to Linkwitz's analysis of corner diffraction, which is far more detailed and exact than most of us mere mortals could ever muster:

http://linkwitzlab.com/diffraction.htm

 

[KaiserSoze]

Maybe if you have really good sub/speaker integration.
Maybe if you have speaker stands that are cheap.
Maybe depending on your SPL desires.

Appropriately, the maybes are multiple. I think there are too many variables to generalize on this point. And of course there was a very good discussion leading up to this, revolving around the potential difficulty for a small satellite speaker to play bass cleanly as low as it needs to in order to blend properly with a typical subwoofer.

 

[KaiserSoze]

I've wondered why we don't use it more. It seems most would disagree with the smoothing below 100 Hz, so that's probably it. I don't typically apply any smoothing there.

One way to find your answer to this is by playing with different equalizers that differ in the number of bands. Better yet, play with a parametric equalizer and experiment to learn how wide the band needs to be before you can readily hear the difference between a +6 dB peak and a - 6dB dip. I was messing around on this computer with different equalizers to try and turn a new pair of headphones into something listenable. At one point I was trying to use a 31-band EQ and became frustrated. The effect was so subtle when changing just one slider that it proved an exercise in futility. I recall a similar experience about ten years ago with a physical equalizer with that same number of bands. I concluded that the optimal number of bands for this kind of equalizer is ten, or one band per octave. To my way of thinking this relates to what you're talking about because, if I insert a +10 dB peak that is 1/3 octave wide and I am only barely able to hear the effect, then 1/3 octave smoothing probably has almost as much granularity as is needed. Maybe a little less smoothing, but not much. If reducing the smoothing reveals a strong peak that isn't audible, then the granularity has probably been increased past the point that has genuine benefit.

 

[beefkabob]

Appropriately, the maybes are multiple. I think there are too many variables to generalize on this point. And of course there was a very good discussion leading up to this, revolving around the potential difficulty for a small satellite speaker to play bass cleanly as low as it needs to in order to blend properly with a typical subwoofer.

Probably can blend cleanly at 75db, but at 105db? Hah!

 

[KaiserSoze]

Also, I would expect M106 + subs to outperform F36 with subs. If you're using subs, I think bookshelves will generally outperform towers for a given price.

I already added a comment to beefkabob's reply to this, so this might be considered "double dipping".

Anyway, a couple thoughts. Most towers that aren't full-blown three-way are so-called 2.5-way, which does a pretty good job of emulating a true 3-way speaker in the sense that the mid-woofer that interfaces to the tweeter (in both physical space and frequency space) is small compared to what would typically be found in a related 2-way bookshelf. Advantage Tower. The total radiating surface area tends to be about a wash, although there is considerable variation in the actual diaphragm diameter for two-way bookshelf speakers and also in the combined, effective actual area of the multiple diaphragms of tower speakers. In specific cases one or the other will enjoy an advantage, but it is impossible to generalize. And then there is the matter of Xmax. Even if the tiny drivers have sufficient mass to achieve a low Fs, they do not generally have Xmax or Xlim that measures up to larger drivers. But the problem with trying to generalize on this point is that there are a lot of bookshelf speakers that use little woofers just as small as the ones found in a typical tower. One thing that can be said with reasonable certainty is that if a small two-way bookshelf speaker has the same size woofer as the related tower speaker using two or three of that same woofer, the tower speaker will be the equal of the bookshelf in terms of the directivity index but will enjoy the benefit of cleaner bass since the driver excursion (for each driver) will be less than it is with the bookshelf speaker, for a given bass frequency and SPL.

 

[KaiserSoze]

Probably can blend cleanly at 75db, but at 105db? Hah!

Yes, and the discussion around this was a good discussion. It all depends on how loudly you intend to play the setup and on your tolerance for distortion. There isn't much that sounds worse than a subwoofer that isn't properly integrated with the main speakers. In fact just thinking about it makes me uncomfortable, wanting to go to my happy place if you know what I mean. Sometimes I think it would be better if no one had ever thought up the idea of a subwoofer separated from the main speakers. It was bound to lead to an alien invasion where the real speakers were slowly and quietly replaced by puny little speakers with puny bass that need to be crossed over not lower than 200 Hz notwithstanding that in the measurements the response is flat down to around 60 to 70 Hz. It is plainly apparent from the distortion measurements that most of these speakers are being driven to a point where the diaphragm excursion has gone well passed linear operation, i.e., well beyond Xmax, but the prevailing opinion is that this is okay because we're not supposed to be able to hear the distortion because the frequency is low. As soon as I buy off on that I'm gonna take a trip down to Florida and see if I can find myself a good piece of swampland.

 

[JustIntonation]

Here's a link to Linkwitz's analysis of corner diffraction, which is far more detailed and exact than most of us mere mortals could ever muster:

http://linkwitzlab.com/diffraction.htm

It isn't I'm modelling diffraction not just from the on-axis (at various distances) but also from all off-axis angles.
And the Linkwitz page you linked to is for diffraction of open baffles. Very different from what we were talking about here.

 

[JustIntonation]

Yes, and the discussion around this was a good discussion. It all depends on how loudly you intend to play the setup and on your tolerance for distortion. There isn't much that sounds worse than a subwoofer that isn't properly integrated with the main speakers. In fact just thinking about it makes me uncomfortable, wanting to go to my happy place if you know what I mean. Sometimes I think it would be better if no one had ever thought up the idea of a subwoofer separated from the main speakers. It was bound to lead to an alien invasion where the real speakers were slowly and quietly replaced by puny little speakers with puny bass that need to be crossed over not lower than 200 Hz notwithstanding that in the measurements the response is flat down to around 60 to 70 Hz. It is plainly apparent from the distortion measurements that most of these speakers are being driven to a point where the diaphragm excursion has gone well passed linear operation, i.e., well beyond Xmax, but the prevailing opinion is that this is okay because we're not supposed to be able to hear the distortion because the frequency is low. As soon as I buy off on that I'm gonna take a trip down to Florida and see if I can find myself a good piece of swampland.

Well, Linkwitz has written the following to which I agree.
Take into account the equal loudness contour and then you'll find that for the 2nd harmonic of for instance 20Hz where it falls is 40Hz and our ear is more sensitive there. So much more sensitive that for a 90dB SPL 20Hz tone, if the 2nd HD is 10% that is 70dB SPL our ear hears it at the same volume as the fundamental. And if the 2nd HD is higher than 10% for 20Hz we hear the 2nd HD as louder than the fundamental.
For the 3rd harmonic it is even worse, a 90dB SPL 20Hz tone can only have 3% 3rd HD before the 3rd harmonic becomes louder to the ear than the 20Hz fundamental.
Our ears/brain can do a trick though, they can fill in the missing fundamental in such a case. But don't think you're actually hearing good deep bass under the crazy distortion figures most 2-way speakers measure. You're not.
https://en.wikipedia.org/wiki/Equal-loudness_contour
So yes, agreed that the prevailing opinion on not being able to hear those crazy HD figures in the bass is complete bs. (also from personal experience)

 

[beefkabob]

There isn't much that sounds worse than a subwoofer that isn't properly integrated with the main speakers. In fact just thinking about it makes me uncomfortable, wanting to go to my happy place if you know what I mean.

I don't think a poorly integrated sub is that bad. It's just not that good either. A well-integrated sub with room correction is amazing, though.

By "happy place", do you mean the men's restroom at the Minneapolis–St. Paul International Airport?