GRIMM Audio LS1c & SB1 DSP Speaker Review

[Frank Dernie]

The estimated in room response shows the LF gradually rolling off from 150Hz.

I'm wondering if this is why I found them to be unspectacular on audition? They were clean and smooth, no question, but they were not the experience I had been expecting.

My guess is that free space bass balance is probably in order to avoid boomy bass in room when the bass box is on the floor. Many of the speakers I have auditioned with what I consider a clean, even non-boomy bass have had this sort of anechoic response.

 

[Sokel]

Are we saying that whilst absolute LF accuracy might not be correct with NFS, that relative accuracy isn’t either? Or can we confidently compare NFS data to assess performance differences between two speakers?

Maybe is as simple as that:

SP used this setting "Low Cut" for obtaining the 3 different results we see at their chart.
(They used 20Hz, 40Hz and 100Hz)

 

[mcdn]

After reading the Grimm docs it seems to me that them calling it a subwoofer is a bit misleading. Its main purpose seems to be to allow increased SPL from 40Hz upwards. A bit like the Lyngdorf/TacT W210 woofers. A 10” driver in that small box is never going to dig really deep. If you can afford the speakers you can afford some proper subs to go with them.

 

[Newman]

This story is a good example of what goes wrong when people try to post-rationalise their sighted listening impressions into analysis of causes.

Hi Newman,
well, this is the difficult point. I do agree, that blind testing is useful, in particular to avoid being overexcited on products, which don't make differences at all.

Also extremely useful on products that are clearly audibly different in blind tests. It is a common wrong assumption that once we know products sound different in blind tests, then the same differences will be perceived in sighted tests, so we can use sighted listening to evaluate what we think of the sound waves themselves. We can not. This is proven beyond doubt.

The measurements here tell us "this is a great product", but in reality I don't fully enjoy it: to my ears for sure they sound sonically correct like many of the flat measuring speakers (Genelec etc). But I found them somewhat fragile for my taste and imaging/dynamics just so-so.
So should I really buy speakers because of measurements telling me that they have to be liked?

Thomas

What I actually said was that it is a mistake to go from sighted listening impressions to analysing what is causing the sound you hear (sighted). "What I heard must be caused by the tiny resonance blip on the chart, or the dip at the crossover, or the slightly elevated distortion, or the use of a large midrange driver (etc etc)". No, it's corrupted by the sighted listening effect, and it needs to be eliminated if one wants to link listening impressions to physical features or measured imperfections.

I did not say that one should not use sighted listening at all in making a purchase decision. Hey, if you can't help yourself from 'hearing' a boxy sound from every speaker with a cabinet (even if there is not a hint of boxy sound and you would be helpless to identify it in blind listening tests), then maybe you simply have to buy a cabinetless speaker to be happy. But it's caused by the same (non-audio) effect that makes some people unable to stop 'hearing' grainy sandy sound from every transistor amp, and smeared timing from every bitstream DAC. The exact same effect.

PS: Electronics are a different story. Here, measurements tell us exactly, if the signal gets to the output undistorted or not. And that's what I want, but can't tell by ear.

See the first part of this post.

cheers

 

[amirm]

I think that @amirm should check into this, if the intent was to include the subwoofer in the HD and other system measurements.

No. The "subwoofer" in this speaker is not a traditional sub. It is a component that becomes part of the speaker, taking it from 2-way to 3-way. Indeed, that is how you configure it in the software. As such, I tested it like any other full range speaker. In the case of the measurements, the speaker is 5 foot above the floor so even near-field, non-anechoic response is going to show response that is closer to anechoic than otherwise. Also, in that near-field graph, I adjust the height of each driver. They actual levels are not correct. They are just a guess on my part (in this case, matching them to the crossover frequencies).

To the extent we test all speakers with deep bass response the same way, they can all be compared the same way. This is the purpose of testing. To take out the environmental effects.

The thing to pay attention to here is the integration of so called 'sub' with the rest of the speaker system. This is what GRIMM is bringing to the table which you would not have with a stand-alone sub.

Finally, I listened to the speaker and noted in the review that deep sub-bass is not there as there is in other full range speakers. What it plays is exceptionally clean but it is at higher bass frequencies.

 

[charlielaub]

So, I have been measuring subwoofers extensively both in-room, nearfield, ground plane (outside) and in an anechoic chamber (@Seas), which have been verified by @AscendDF to measure very closely to the NFS below 100hz.

The result in the anechoic chamber is way leaner than even a nearfield or ground plane measurement, and obviously nothing close to what you'd typically measure in-room. While what we see below 50-70hz in an anechoic or NFS measurement may technically be "correct" given what we are measuring, it is not a good way to understand real world performance.

Based on my experience I think the result we see here is misleading for the real world bass performance of the Grimm, and everyone saying they are disappointed in the bass performance are likely jumping to conclusions based on measurements you do not properly understand.

TL;DR: If there is anything wrong with this measurement I don't know, but even it were correct, it may not properly indicate real world performance below 100hz.

Yes, what you observe and state above is typical when there are different measurement conditions. For example, without a boundary (eg the "ground" of a ground plane) you lose 6dB of reinforcement of the low frequencies. But in this case with he Grimm system there is around 12dB or more of "lean-ness" and that seems to me to be too much to explain away the difference from e.g. pathlength or 2pi vs 4pi space, etc.

Also, those measurement related level changes would not explain why the nearfield measurement of the woofer, and the "system" measurement that includes the subwoofer, are essentially identical below 100Hz. Where's the subwoofer output below 100Hz? Its' not just reduced by a few dBs, it's pretty much absent alltogether (or so it seems to me).

 

[Vuki]

No. The "subwoofer" in this speaker is not a traditional sub. It is a component that becomes part of the speaker, taking it from 2-way to 3-way. Indeed, that is how you configure it in the software. As such, I tested it like any other full range speaker. In the case of the measurements, the speaker is 5 foot above the floor so even near-field, non-anechoic response is going to show response that is closer to anechoic than otherwise. Also, in that near-field graph, I adjust the height of each driver. They actual levels are not correct. They are just a guess on my part (in this case, matching them to the crossover frequencies).

To the extent we test all speakers with deep bass response the same way, they can all be compared the same way. This is the purpose of testing. To take out the environmental effects.

The thing to pay attention to here is the integration of so called 'sub' with the rest of the speaker system. This is what GRIMM is bringing to the table which you would not have with a stand-alone sub.

Finally, I listened to the speaker and noted in the review that deep sub-bass is not there as there is in other full range speakers. What it plays is exceptionally clean but it is at higher bass frequencies.

NFS measurement strangely resembles Grimm's LS1 measurement without subwoofer??? Almost to a dB.

 

[olieb]

Where's the subwoofer output below 100Hz?

That would be my question too. And on top the distortion in LF looks a lot like that of a very good 8inch mid woofer with xmax=5mm (producing the measured output spl) and not like that of a 10inch long throw sub with sophisticated motion feedback.

 

[charlielaub]

In an effort to make it clearer I overlaid the plots of the nearfield measurements and the system response (from the HD measurements) below 200Hz. You can see that the woofer nearfield response is basically identical to the "system" frequency response shown in the HD plots. Also you can see the subwoofer nearfield response - it should be contributing to the system response below 100Hz by extending and flattening it compared to the woofer nearfield. But since the red and green lines overlap, to me this seems to indicate the sub was off during the HD measurements.

 

[Sokel]

In an effort to make it clearer I overlaid the plots of the nearfield measurements and the system response (from the HD measurements) below 200Hz. You can see that the woofer nearfield response is basically identical to the "system" frequency response shown in the HD plots. Also you can see the subwoofer nearfield response - it should be contributing to the system response below 100Hz by extending and flattening it compared to the woofer nearfield. But since the red and green lines overlap, to me this seems to indicate the sub was off during the HD measurements.

View attachment 452442

Roll off looks the same as SP with the "Low Cut" set at 100Hz:

 

[trevor_bartram]

This discussion of bass reminded of why after many years of struggling with stand-mounts & a sub, initially fiddling to find the 'best' locations, then fiddling with with sub level, phase & frequency cutoff when a recording doesn't sound 'right', I gave up & went with tower speakers. Now both acoustic bass & organ music sound right & no more fiddling!

 

[charlielaub]

@trevor_bartram That has pretty much nothing at all to do with Amir's measurements done with a Klippel near field scanner... or a nearfield measurement for that matter.

 

[amirm]

But since the red and green lines overlap, to me this seems to indicate the sub was off during the HD measurements.

Huh? Then how do you explain my near-field measurements of the sub?

I specifically checked to make sure the sub was working and indeed it was.

 

[charlielaub]

Huh? Then how do you explain my near-field measurements of the sub?

I specifically checked to make sure the sub was working and indeed it was.

The sub was obviously working when you took the nearfield measurement!

What puzzles me is the lack of subwoofer band SPL within the system ("fundamental") response in the HD plots. I don't see any evidence that the subwoofer was contributing to the system SPL in those measurements, and this would explain why the HD levels are relatively high below 100Hz. It's what I would expect for a circa 6" driver trying to operate "down there". The sub will or should have much lower HD. It has an advanced feedback system that is claimed to lower HD by 30dB. It doesn't seem correct that the HD level should be 10% at 50Hz with a playback level of 96dB when the subwoofer level matches the system level correctly.

The HD levels just seems very odd to me, and the lack of subwoofer output can explain that very easily. So that is my theory at this point.

 

[olieb]

Huh? Then how do you explain my near-field measurements of the sub?

Obviously the sub was working, certainly during the near field measurement and I guess in the other measurements too.
But it does not really "look" like it was contributing much.
I compared the levels at 40Hz in relation to 150-200Hz for the measurements.

It seems the sub contributes only a tiny bit of sound energy, bringing the SPL from -10dB (mid woofer alone at 40Hz) to -6dB.

 

[sigbergaudio]

Are we saying that whilst absolute LF accuracy might not be correct with NFS, that relative accuracy isn’t either? Or can we confidently compare NFS data to assess performance differences between two speakers?

If measured the same way, we should theoretically be able to assess the differences between speakers.

 

[charlielaub]

Obviously the sub was working, certainly during the near field measurement and I guess in the other measurements too.
But it does not really "look" like it was contributing much.
I compared the levels at 40Hz in comparison to 150-200Hz for the measurements.

View attachment 452444 View attachment 452445

It seems the sub contributes only a tiny bit of sound energy, bringing the SPL from -10dB (mid woofer alone at 40Hz) to -6dB.

If it is 6dB down compared to 150Hz then maybe it is a 2pi 4pi thing? E.g. the Klippel NFS is making 4pi (full space) measurements, and Grimm has designed the system to operate in a real room (a 2pi space) so that the subwoofer gets full floor reinforcement, which would bring the level up by 6dB WRT full space. Since the woofer is elevated off of the floor by a good bit, it would not get much floor-boundary reinforcement and so its level would not change in a real listening room.

But the relatively high HD level at 50Hz still bothers me. How to explain that?

 

[olieb]

If it is 6dB down compared to 150Hz then maybe it is a 2pi 4pi thing?

I don't think so. If the sub brings the level at 40hz up (only) +4dB that means the sub level is lower(!) than the midwoofer's at that frequency or they are out of phase. In both cases there is something off.
My estimation is that the sub at 40Hz has only a SPL of about -12dB relative to the level of the speaker at 150-200Hz.
If that is, as Amir explained, the highest achievable bass level of the system, I am puzzled.

 

[Sokel]

I don't think so. If the sub brings the level at 40hz up (only) +4dB that means the sub level is lower(!) than the midwoofer's at that frequency or they are out of phase. In both cases there is something off.
My estimation is that the sub at 40Hz has only a SPL of about -12dB relative to the level of the speaker at 150-200Hz.
If that is, as Amir explained, the highest achievable bass level of the system, I am puzzled.

On top of that, we have to take in account that it uses what it seems as a second order filter between woofer and sub (or between mid and woofer more correctly if set-up right) so both should contribute to higher level.
Nothing as such is evident there.

 

[Vuki]

THD in bass is just ca. 3dB better in (NFS) measurements with subwoofer than without it? Unbelievable.