GR Research LGK 2.0 Speaker Review (A Joke)

[Talisman]

And anyway they are also as bad as a disease

 

[Prana Ferox]

My impedance sweeps are very high resolution with Kelvin probing. As such it sometimes shows effects like this although I have not seen it this severe in the past.

What did poor Kelvin do to deserve this

 

[Toni Mas]

Baffle step compensation.

Considering the parts involved in this case, it seems that more than baffle step correction is the target intended. BSC can simply achieved with one paralell R//L while it looks like more components are used (additional RLC network) to add some kind of eq around 2000 Hz, as also indicates the impedance curve. As commented before, despite the glowing metal phase plug, these drivers seem very far from exemplary...

 

[hardisj]

What did poor Kelvin do to deserve this

 

[levimax]

Erin, you know what, I didn't agree with you at first but I think you're right. This is one of the most messed up impedance response I've ever seen. Unless the box design is truly bizarre (some kind of horn loading or something) there is something up with this speaker. You and I both know what typical bad-speaker-impedance plots look like, little wibble wobbles above 200hz, but this kind of chaos doesn't make sense.

GR could be the worst speaker designers on planet earth, but Dayton doesn't sell drivers that do this, and I don't think the crossover is that complex. In other words, either something is wrong with the construction, or something truly bizarre is happening. Let's not forget that a LIMP jig or DATs is one of the diagnostic tools that GR has, along with their radio shack spl meter and 'Brothers in Arms' CD.

@Rick Sykora can confirm, but the speaker looks like a simple slot loaded port, no bracing, and a moderately complex crossover (2 coils, 3 caps and some resistors, which is not what I would consider minimal for a fullranger).

I am not an expert on speaker design but for a driver like this I was under the impression that you are supposed to cross them over before resonance to avoid problems as things become unstable at the resonant frequency. The resonant frequency of this driver is 120 Hz which is right where things get crazy. The published impedance data shows the strong peak at 120 Hz and some phase changes as well and it not that much different than what Amir measured. To me it looks more like the design is broken rather than anything mechanically wrong with the speaker.

 

[Toni Mas]

I am not an expert on speaker design but for a driver like this I was under the impression that you are supposed to cross them over before resonance to avoid problems and things become unstable at the resonant frequency. The resonant frequency of this driver is 120 Hz which is right where things get crazy. The published impedance data shows the strong peak at 120 Hz and some phase changes as well and it not that much different than what Amir measured. To me it looks more like the design is broken rather than anything mechanically wrong with the speaker.

View attachment 211834

Yes, this is part of the problem... The driver's Fs is around 120hz, so that is useless because lacking any bass. But the cabinet is a Bass Reflex design using the sub tuning trick in order to boost somewhat the bass. In this case the cabinet is tuned around 80hz (the minimum between impedance peaks), and the result is an insane peak above 100hz ( which also interacts with the passive Eq netwoork...). This insane BR tuning is what causes distortion because cone movement cannot be under control as a sane BR design would allow. But this would also mean sacrifice bass, tuning the BR at 120Hz or above.

 

[Dave Tremblay]

You didn’t measure it, but I’d imagine IMD is pretty terrible. Doppler distortion alone would be extremely high in a small cone full range. Add to that the excursion this driver is seeing under the tuning frequency and I bet it’s a wild ride.

 

[sofrep811]

Many thanks for this review. I used to watch this guy as of today. I assumed his speakers might live up to his faux humble an folksy pastor style he uses bashing other speaker companies.



The build thread was eye opening. I swear, those drivers are exactly what my old Mission 772 bookshelf had in them. That brass colored cone is a giveaway. Maybe he bought in bulk when Mission quit using them. Haha. Doubtful as they’re on other speakers—but who knows.



Another one bite’s the dust.

 

[amirm]

You didn’t measure it, but I’d imagine IMD is pretty terrible. Doppler distortion alone would be extremely high in a small cone full range. Add to that the excursion this driver is seeing under the tuning frequency and I bet it’s a wild ride.

Yeh, I confess during listening tests I wished I had some IMD tests. This speaker does provide a control sample to see if IMD tests are working to reveal such issues. In the past I would get just get IMD results all of the place (due to wild frequency response differences) so there was no way to know if they were showing anything useful. A single driver also makes it easier to arrive at frequency pairs as it plays them all. A 2-way speaker doesn't do that.

 

[sofrep811]

I was lurking on his site and now I'm very interested to see a test of his upgrades. At $250-$300 I have a feeling those might be snake oil.

Wish I still had m Dynaudio! This is what he proclaims:

The price of Sonicaps have just gone up and it caused a slight increase in the cost of this upgrade. This kit includes everything you need to correct a number of issues and take this speaker to another level across the board. Please see the videos and measurements in the accordion below. The kit includes all new parts, a set of tube connectors, a sheet of No Rez and new wiring.

https://gr-research.com/product/dynaudio-special-40-upgrade/

 

[617]

What does a crossover do in a full range single driver speaker?

Thanks for always taking the time to correct people, it's very much appreciated.

 

[Hipster Doofus]

Thanks again for setting forth some data as opposes to a video claiming this is my top speaker after 20 try’s…

IMO, NOT EVEN A HUMBLE ONE…
thanks so much from those amongst us who really have no other alternative then to watch hucksters and so called reviewers dealing in flowing terms that have no assigned values. There is seldom anything in most reviews that someone could take and compare to the next flowing review. Even when a good review sites include specs and lab test they are left at the bottom and without context….what the world needs now is data with context.

what you find here …

reviews done the same way each time And in the same format,
reviews on every type of device and gadget
reviews that paint a product in a truer light
with a few notes when needed on the charts
tons of measurements
then a little subjective notes or context why a measurement is good or bad….

the data presented is way over my head but …when presented in the same format I can begin to grasp things

Ok Ok what I really wanted to say maybe is maybe Amirm is THE LITTLE GIANT KILLER

 

[elvisizer]

So it’s not a crossover but an equaliser?

more of a filter yah

 

[Hipster Doofus]

 

[D!sco]

In the past I would get just get IMD results all of the place (due to wild frequency response differences) so there was no way to know if they were showing anything useful.

Can you explain a bit more? Are the results inconsistent? Not sure what you mean by wild frequency response differences.

 

[amirm]

I was lurking on his site and now I'm very interested to see a test of his upgrades. At $250-$300 I have a feeling those might be snake oil.

There is an upgraded speaker here. An easy case though as the response of that speaker was pretty flawed as shipped.

 

[ROOSKIE]

Conclusions
Ah, little giant killers... who doesn't want to see an underdog win? Put in a spokesman in front of the camera that tells the nice story and you just want to believe it. I know I believed it a lot more than what I experienced with the speaker. Yes, the tonality is good overall. No, you can't take a midrange+tweeter driver and pretend it can play bass at the same time. It simply cannot. How on earth anyone can say this speaker is usable let alone high-fi is beyond me.

Is Danny this oblivious to distortion? This is not subtle stuff folks. Measurements show extreme amount of distortion and listening tests easily bring out the same. And of course physics solidly predicts it as well.

There is a reason my acoustic measurements from day one have included distortion measurements. And why I listen for dynamic behavior in my listening tests. Hi-fi is about enjoyment and there, you want to have some volume. The LGK 2.0 simply cannot go there. The driver seems to be designed for a boombox or something with matching electronics to control what it can or cannot do. Sticking it in a box and calling it great is one of the biggest farces I have seen in audio business!

Well said.
This is from my post in the original build thread.
I point out that the design has serious xmax limitations and those are based on spec xmax. Actual xmax of the driver apear even lower based on your actual HD testing.

"Danny doesn't specify what thickness the enclosure is but it looks 3/4 in to me so I use that when I plugged in the design parameters.

He appears therefore to be using a 0.10cu ft enclosure. With the 5.75x4x0.50" port I get a tuning of 88hrz which seems to match the impedance chart published here. It may actually be slightly different but it is deff tuned somewhere between 85-92hrz.

That gives the driver a bit of boosted bass (+2db or so) from around 85hrz to 200hrz

Rapid decline after that and is about 10db down around 60-65hrz.

At 60hrz it can only handle 2 watts of power. From 65hrz down xmax is exceeded with more than 2watts & that 2.5mm may already be an issue for the driver in reality. It is 10db down here or more so the HD won't be as huge of an issue (even if 100%)but the flopping driver needs to be stopped or IMD with surely be nasty.
GR does claim 15watts but it can only do this right at fb, the driver's Xmax is very, very much exceeded in the whole bass and midbass/lower midrange area with 15watts. No way I drive it with 15 even if High Passed and expect a great sound.

I think 5watts (maybe 10watts max)with a High Pass at 75hrz/Lr4.
That gives 95db SPL max for a single unit @1meter when High Passed vs maybe 90db at 1meter for the full range use case.

Not impressive SPL output though for a single 3" driver not bad. Likely enough for a desk or most types of background use.

It will be interesting to the see the HD levels here and to see if IMD is a very audible issue."

By this time, I actually expected the speaker to sound good (based on spin data). Boy was that not the case. At any listening level above faint music, there would be this nasty warbling sound to vocals which would progressively get worse with volume. I am talking about way below the point where it crackles. The only time this was not super audible was if there was no bass at all. My female tracks are not bass heavy but the bit they had, caused this speaker distort so badly that it was unlistenable. I have tested over 200 speakers and never heard a speaker with such poor response.

By chance I had my desk lamp above it so could easily see the shadow of the driver below the cabinet. As soon as I would see any vibration in that shadow (due to the cone moving), the game was over. And again, this happened at very modest volumes with me sitting just 3 feet/1 meter away from the speaker!

Suspect bass being the problem, I took out the EQ tool and put in a sharp high pass:


This managed to get rid of significant amount of that warbling effect. But then there was so little bass that one was left thinking the sound was just too thin.

So I was wondering bad in that build thread if IMD would be just bad or really bad and as you discovered it is impossibly bad.

 

[amirm]

Can you explain a bit more? Are the results inconsistent? Not sure what you mean by wild frequency response differences.

In electronics, I can generate two perfect tones that are always at the same level. Then we can see the intermodulation distortion. With two speakers with varying frequency response, the signals themselves vary so will their intermodulation. So two speakers with same non-linearity but different frequency response will demonstrate different levels of intermodulation which is not correct.

Then there is the issue of what two tones to pick. Let's say I pick one at 50 Hz and the other 3 kHz. This speaker can't reproduce 50 Hz so the results would not apply to it.

 

[D!sco]

So the issue isn't just that there is no standard, but also that the test itself produces unreliable results? That's frustrating. If you were to tackle this, how would you approach it? I've seen Erin's IMD graphs in his driver measurements, often for bass and larger diameter woofers.

 

[tuga]

At first this looks radically different than what the company shows

Try adding smoothing to your plot and it will look radically similar. You're comparing apples with oranges...

Other than the beaming it is quite good. It just needs a tweeter and a woofer.