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Build of GR-Research LGK 2.0 Speaker

Rick Sykora

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Decided to take a break from Directiva as Amir asked that I build a LGK 2.0 for him to test [Review posted now: https://www.audiosciencereview.com/...research-lgk-2-0-speaker-review-a-joke.34783/]. As seemed like an easy project, was happy to help. After looking over the pricing, we decided to buy the premium parts with the flat-pack cabinet. I ordered the flat pack first but the parts arrived earlier. Here is a look at the parts for one of the pair:

49AD9F78-53ED-4C87-88B4-76A7CF09D574.jpeg


So from left to right, we have red and white shrink tubing, red and white tube connectors, red and white solid core wire, driver screws, some solder, green Dayton precision resistors, a black Erse capacitor, a white Sonicap, a black bypass cap and the crossover (technically filter) inductors.

Oops, forgot the alleged star of the show - the LGK driver:

7523F797-4594-49C0-A775-F52B6F13D789.jpeg

5A0961F3-7DD8-46C4-B9FD-2E305DB15D94.jpeg

Except for the pretty phase plug, the only other remarkable aspect is the size. It is really small (smaller than many midranges I have used).

Also included (but not pictured) is a printed copy of the crossover schematic. The parts were all nicely packed, but after removing the cardboard from around the larger inductors, I noted they were more oval shaped and not very cleanly wound. Here is the worse of the 2 inductors…

0E1FBC7D-995C-4AD1-8176-AB653CECC31B.jpeg

I used the better of the 2 for the build as it measured the exact inductance specified. The pictured one measured slightly higher but within tolerance. I questioned GR over the inductor quality but their only response was that they were struggling with suppliers. As it measured fine, kept going…

The flatpack arrived about a week later and the contents were extremely well-protected in multiple layers of shrink wrap and surrounded by foam blocks in a box that was over twice the size of the contents. Hope they get good shipping rates!

Here is a pic of the contents (for one speaker):

B60ED96F-2881-4A14-B4AC-D17C7A143E95.jpeg


From left to right is the front baffle, crossover board, back baffle, duct board, top/bottom and the sides. All were nicely machined appeared to be nice quality MDF. No other documentation was included, but a cabinet drawing is posted on the GR website. A quick note as I realize my pic shows the inside view of the front and back baffle. :oops: As you can see, the back baffle has access cutout. This is needed as the driver cutout is too small to allow the assembled crossover to be inserted. More on this later…
 
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Rick Sykora

Rick Sykora

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Since there were no cabinet assembly instructions, did a dry fit to get a feel of how the parts would go together.

725BB384-D7F7-4DE2-832C-2190041AD146.jpeg


After I had assembled the flat pack, one thing was glaringly obvious - the sides were not rounded over as shown on GR pretty website pics. Checking the cabinet plans, they called for a 19mm rounded edge. So much for a simple build!

The recommended location for the crossover was on top of the vent shelf. Shown here:

A0038A08-AFBD-4440-96DB-0323AA4D0849.jpeg

There are 8 parts to the filter and so was going to be a tight fit so I also removed the back panel from the rear baffle to get some more perspective.

909C9D34-3976-49BB-AA0A-86C1D532BE47.jpeg

Lacking any instructions, I looked at the prototype crossover posted on AudioCircle and pondered it. Did not like having to jam all those parts on top of the vent, so started to look elsewhere. In hindsight, one of the sides may have been a simpler choice but have always liked less connections and shorter wiring. So I considered the back of the access panel, but it is even smaller than the supplied crossover board. So put that aside and decided to get the cabinet glued together…
 
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Rick Sykora

Rick Sykora

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Rick Sykora

Rick Sykora

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Rick Sykora

Rick Sykora

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As I mentioned, no build instructions are included, so the sequence here is my own. My goal is to make sure critical joints get glue between the surfaces. You may have a better plan. I started with one of the sides face up and glued on the vent shelf. To maximize my time, I also glued the back in place. Note along with the side joint, glue is also needed where the vent meets the back. Rather than clamp, I like to use gravity and, to keep square, use my table saw fence, like so:

72C5FD16-52FB-4549-881E-ACAF0CC98E5D.jpeg


Once the glue sets, I add the next piece. In this case, it is the front:

B7B5721C-8272-4780-8557-2BFBC3A99059.jpeg


You can see I like to add some extra glue to ensure a good seal.
Next I attached the other side…

7CE773F7-5978-4EAA-B8C2-EAD83018E021.jpeg


And then the top…

EE13AA31-46C7-45EC-8FD8-34EC158A28BC.jpeg


and the bottom…

98A2B932-EB66-44C1-B2D4-9948EE130154.jpeg


And let the completed cabinet set overnight to allow the glue to cure before routing…

Note: will fix picture orientation on PC as am adding them using my IPad and does not always preserve the original photo position.
 
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617

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That is a rough flatpack
 

alex-z

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Could you measure the T/S parameters of the driver, and maybe the raw 0 and 30 degree frequency response?

I am curious if it has potential as a dedicated mid-range driver.
 
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Rick Sykora

Rick Sykora

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Could you measure the T/S parameters of the driver, and maybe the raw 0 and 30 degree frequency response?

I am curious if it has potential as a dedicated mid-range driver.

These are all posted on the GR website so have no plans to do.
 
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Rick Sykora

Rick Sykora

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So at first I thought this was a simple build, but since the flat pack did not have the roundovers, it is less simple. For the uninitiated considering these, this means that you need a router that handles a 3/4 inch roundover bit that usually has a 1/2 shaft (no wimpy compact routers need apply).

Since I needed previously, already had the router bit but also needed to change the collet and the baseplate. Once this was done, I stoked up my courage and made several passes on scrap material to get the depth right. This is the most massive bit I own and when it spins up, you need a steady hand and sturdy work surfaces. Slipping with this bit might mean rebuilding the cabinet. This front baffle is not very big either so is easy to tilt slightly and undercut or over cut.

Fortunately, my practice paid off as it turned out well…

C2623654-5E64-4FB0-9BD8-4251906765F0.jpeg

After a little sanding and cleaning, tried a dry fit of the driver and discovered some other issues:
  1. The supplied driver screws were too small and would not tighten. A quick check revealed they should work on the back panel, so saved for later and used some of my #6 screws.
  2. The driver recess was too deep and likely would cause diffraction. Clearly was going to need some remediation. Here is a pic…
85D299CE-6506-4268-A6B6-E0209114B39E.jpeg


At this point, did some follow up with GR. The screws were a known problem. Offered to either sand down or add more gasketing to the driver recess, they opted for the additional gasketing. Now I needed to return to building and mounting the filter…
 

ta240

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I feel bad for anyone that buys this without the knowledge and tools to fix the short comings of this kit. And, iconically, if you have the needed tools and knowledge then you probably don’t need an all in one kit. This is the type of first time project that can turn people off of DIY.

At around $300 the lack of any instructions and round overs as well as the overall fit and finish is ridiculous.

He is showing the $450 finished cabinet picture for the kit listing instead of the flatpack picture that he should be showing, that has to be a huge letdown for buyers.
It would only take a few minutes to rough out some semi-decent build instructions; I guess he was too busy posing for the giant pictures of himself that are all over the site.
compare the pre-roundover picture above with what is shown for the kit on his site.
temp1.jpg
 
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mightycicadalord

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I would agree these should have round overs already done, and compared to the flat packs that you can get with PE kits, the joinery and cuts seem pretty meh.

You got that cabinet together and routed quick there Rick!

Looking at some of the costs, I'd say this is gonna be a tough sell, you can get some hitmaker mt's for less or amigas for the same cost which are going to just be much better speakers, though perhaps different use case.
 

Smitty2k1

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Looking forward to the review on these. Window shopping small desktop speakers at the moment
 

ROOSKIE

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Yes, but should have mentioned, it is also high EBP driver (162). Really more suited to a closed box.
Hi, EBP of 162 is best for vented.
Low EBP is sealed. (Less than 50)
For sealed you want low fs& higher Qes, so the EBP would be a lower number.
For vented higher fs and lower QES.

EBP is fs divided by QES for those wondering.
So less <50 sealed
=50-100 is dealers choice
>100 is vented.

Also QTS is .628 so any sealed box using this driver will have a higher q above critically dampened. It can be optimized for .7 but the fs is very high so it won't have bass.

What concerns me is a driver with an fs of 113 and a tiny cone moving a max of 2.5mm. This thing is going to to max out at 75-80db if using in the far field and have interesting bass. Curious what it sounds like. For near field it might be pretty fun though.
Many single driver options exist that cost far less than this though as we all know.
 
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Rick Sykora

Rick Sykora

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As part of building the filter, the tube connectors needed to be installed. I had seen The GR video on this, but did not really align with my plans (as you will see below). The tube connectors holes were predrilled but too small to comfortably pound in. After a little filing, applied the recommended silicon seal and hammered them in place.

19692029-65FB-4090-94CF-9F3192B68035.jpeg


As mentioned earlier, placing all the filter components on the back access panel was too tight (notably to leave enough distance between the inductors). The supplied inductors had long leads, so I resorted to splitting the filter in half. The filter circuit has a main compensation part and a notch filter. As each has a one of the inductors, 2 boards allowed me to space them far apart as you can see here:

0C45DC05-867A-4D0E-8275-2707F5E56CB5.jpeg


All connections were made with the supplied solder including the driver connections.

For comparison, here is the prototype filter posted on AudioCircle:

1651234903904.jpeg


On the supplied kit, the brown Miflex bypass cap has been replaced by a much smaller (unidentified) one. Note this crossover needs wire from the tube connectors and to the driver. By mounting on the back of the access panel, mine only needs wiring from the filter to the driver. All hard mating surfaces had butyl rubber applied to minimize vibration and both boards are attached with 2 screws each.

The cabinet plans called for some internal damping material (not supplied), so grabbed a handful of Acousta-Stuf, fluffed it up a bit and placed between the driver and the filter. Here is pic:

5A13FFE3-85DC-4A1E-90A1-307AB2552212.jpeg


Did not use the supplied heat shrink tubing, but used some smaller diameter pieces in places where potential shorts might occur. Did a quick impedance check to validate the build and its is ready for Amir…

956EFC40-E363-4FC7-B046-369E8D4C704A.jpeg
 
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Rick Sykora

Rick Sykora

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Hi, EBP of 162 is best for vented.
Low EBP is sealed. (Less than 50)
For sealed you want low fs& higher Qes, so the EBP would be a lower number.
For vented higher fs and lower QES.

EBP is vs divided by QES for those wondering.
So less <50 sealed
=50-100 is dealers choice
>100 is vented.

Also QTS is .628 so any sealed box using this driver will have a higher q (higher than .7)

What concerns me is a driver with an fs of 113 and a tiny cone moving a max of 2.5mm. This thing is going to to max out at 75-80db if using in the far field and have interesting bass. Curious what it sounds like. For near field it might be pretty fun though.
Many single driver options exist that cost far less than this though as we all know.

Thanks for the correction, I misstated. The driver does have a high Qts though.

Will fix my earlier post. I usually rely on Bassbox to determine alignment fit, but this driver is not in database and did the calc myself. It is what can happen when you crutch on software. :facepalm:

Is def a nearfield speaker and is easy to bottom the woofer. More to come in my measurements…
 
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rebbiputzmaker

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Hi, EBP of 162 is best for vented.
Low EBP is sealed. (Less than 50)
For sealed you want low fs& higher Qes, so the EBP would be a lower number.
For vented higher fs and lower QES.

EBP is fs divided by QES for those wondering.
So less <50 sealed
=50-100 is dealers choice
>100 is vented.

Also QTS is .628 so any sealed box using this driver will have a higher q (higher than .7)

What concerns me is a driver with an fs of 113 and a tiny cone moving a max of 2.5mm. This thing is going to to max out at 75-80db if using in the far field and have interesting bass. Curious what it sounds like. For near field it might be pretty fun though.
Many single driver options exist that cost far less than this though as we all know.
These are more like big headphones in boxes not really room worthy speakers. I guess OK for a desktop possibly, but don’t see the points personally. Single drivers do have their appeal and they can sound nice, not measure well usually… But sound nice. Lowther was some of the best early on of this genre. Backloaded horns were the way to go.
 
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ROOSKIE

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Thanks for the correction, I misstated. The driver does have a high Qts though.

Will fix my earlier post.

Is def a nearfield speaker and is easy to bottom the woofer. More to come in my measurements…
High QTS is usually for huge sealed, free air or passive open baffle.
In this case the qts is higher at .628 but not high. (Over .9 )
It seems suited as a vented box overall but the darn thing is just so small.

Anyway if it was in a sealed box optimized for a .7q it would be 3-4 times vas in size( 3-4l)and likely have zero meaningful bass as it would start rolling off pretty high.
 
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