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Build of GR-Research LGK 2.0 Speaker

Verdinut

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It is port appropriate because the fs is higher.
It is a relationship between the two.
With higher fs drivers(90-120) higher QTS/QES(.5-.9) is good for ported boxes.
Over .9 would change things a bit but that would be a very unique driver.
Model this driver yourself.

With a higher fs driver you are tuning the port to support what is the upperbass/midbass and not the lower bass region. Therefore the desired QTS/QES parameters are different from when tuning for the tradition bass zone.
In a driver where the fs is lower and the natural response already covers the midbass you would get a peak or boom there, not so in a driver like this where the natural response is severely rolled off in the midbass and needs support.
If this driver was in a small sealed box it would have no bass at all and barely any lower midbass. Completely unsuitable response in this use case.
In my opinion, you build a box to obtain good low frequency performance. By venting a box for a driver with a Qts higher than 0.5, you're aiming for good LF performance at the cost of poorer transient response. You don't gain anything and you might as well keep it sealed. All the experts say so. I have been building speakers for over 50 years. Just get a good loudspeaker building software and you will find the right answers.

That's why you need a lower Qts for a vented design. By the way, a high Qts speaker in a small sealed box might still produce some low frequency response, but not as efficiently as the one in a vented box. The purpose of an enclosure is to isolate the back wave produced by the driver from the front wave in order to get a LF response, the proof being that you can get subwoofers in 1 cubic foot cabinets producing low frequencies. The LF response depends on the Thiele-Small parameters of the driver and the box design.
 

Wolf

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Expert or not, sometimes you have to vent it to get a reasonable bass end at all. I used a driver with Qts of 1.2, and stuffed the tar out of it (6.25oz in 4 ltrs) to lower the ripple and improve the transient response. I usually can reliable vent a driver up to about Qts = 0.6, but there are exceptions with higher Fs/smaller drivers just as Rooskie states.
 

ROOSKIE

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In my opinion, you build a box to obtain good low frequency performance. By venting a box for a driver with a Qts higher than 0.5, you're aiming for good LF performance at the cost of poorer transient response. You don't gain anything and you might as well keep it sealed. All the experts say so. I have been building speakers for over 50 years. Just get a good loudspeaker building software and you will find the right answers.

That's why you need a lower Qts for a vented design.
This is a small 3" driver with high fs.
You can not look at QTS by itself. By itself it means nothing. You need to know at least the FS and VAS and additionally the design goals.

You can not ignore what this driver is. As stated, model this driver or any similar driver. This is a tiny driver being used as a FR, 1 driver design. The requirements are different as the speaker drivers low frequency extension is beyond sub optimal and nearly all of these type of woofers are as such.
The high-ish (relative to a more typical sized woofer's parameters QTS) actually helps give a decent box size to work with.
It is true that there is risk of poor transient response and phase issues with this particular design and I am curious what the Klipple finds and Amir hears. I have not made any super small 1 driver system like this myself so I don't know quite how this speaker is going to handle the tuning, but this is typical for the genre.

By the way, a high Qts speaker in a small sealed box might still produce some low frequency response, but not as efficiently as the one in a vented box. The purpose of an enclosure is to isolate the back wave produced by the driver from the front wave in order to get a LF response, the proof being that you can get subwoofers in 1 cubic foot cabinets producing low frequencies. The LF response depends on the Thiele-Small parameters of the driver and the box design.

A high QTS driver in a very small box will typically give a huge bump in the response and then a dramatic fall off.
The box is acting as a spring which is very relevant in a closed box design (along with the back-wave isolation to ensure the opposite phase wave does not interfere) and typically you need not insignificant bass boost and huge xmax for small sealed boxes with 20-30hrz bass...but the designs and combinations are really sky is the limit.

In any case for this type of speaker, the LGK 2.0, you likely going to see High Fs, higher Q's and porting. Does it sound good? IDK.
 

Verdinut

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This is a small 3" driver with high fs.
You can not look at QTS by itself. By itself it means nothing. You need to know at least the FS and VAS and additionally the design goals.

You can not ignore what this driver is. As stated, model this driver or any similar driver. This is a tiny driver being used as a FR, 1 driver design. The requirements are different as the speaker drivers low frequency extension is beyond sub optimal and nearly all of these type of woofers are as such.
The high-ish (relative to a more typical sized woofer's parameters QTS) actually helps give a decent box size to work with.
It is true that there is risk of poor transient response and phase issues with this particular design and I am curious what the Klipple finds and Amir hears. I have not made any super small 1 driver system like this myself so I don't know quite how this speaker is going to handle the tuning, but this is typical for the genre.



A high QTS driver in a very small box will typically give a huge bump in the response and then a dramatic fall off.
The box is acting as a spring which is very relevant in a closed box design (along with the back-wave isolation to ensure the opposite phase wave does not interfere) and typically you need not insignificant bass boost and huge xmax for small sealed boxes with 20-30hrz bass...but the designs and combinations are really sky is the limit.

In any case for this type of speaker, the LGK 2.0, you likely going to see High Fs, higher Q's and porting. Does it sound good? IDK.
It's no use discussing with you any longer. A 3 inch speaker is not a woofer and that's the end of our discussion.
 

thewas

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Bass reflex (if the TS parameters allow) makes especially sense in such small wide band designs as it reduces driver excursion around its tuning region and thus also the very problematic IMDs. A steep highpass filtering below of course should be used too.
 
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Rick Sykora

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On its way to Amir!
 

ROOSKIE

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Bass reflex (if the TS parameters allow) makes especially sense in such small wide band designs as it reduces driver excursion around its tuning region and thus also the very problematic IMDs. A steep highpass filtering below of course should be used too.
Definitely.
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.
 
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Rick Sykora

Rick Sykora

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Definitely.
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.
You are pretty much right on...

The filter does nothing in the lower bass and a passive high pass filter would be too big and too pricey. The filter design is essentially a baffle step comp part and a notch filter to help tame some high end ugliness.
 

sofrep811

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I owned a pair of Mission 772 speakers and those drivers look familiar
Mission.jpg
.
 

thewas

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Rick Sykora

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After the review, not suggesting that anyone spend their money on this kit, but…

I think it is noteworthy that this thread is more complete build information than GR currently supplies. The kit docs only include a filter schematic and a cabinet drawing. Note this is more than 2 months since the kit started shipping. Despite much protest over damping material in our Encore build, the GR website does not even mention a need for any. I added some based on something I found in an Internet search.

As a parting note, a friend mentioned our tone (mine as well) has been pretty harsh towards GR. While I have agreed to improve, when a vendor fails to deliver basic aspects of a product, I think it is fair to warn potential buyers. In my case, I usually give the vendor notice and a chance to respond to shortcomings. Most of the time, GR has been responsive (as I mentioned earlier in this thread). While this is good, actual corrective action is more critical. In that regard, I regret to report, GR too often fails to deliver.
 
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617

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I think the harshness comes from the fact that it gives us garage and basement speaker tinkerers a bad rep.
 
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Rick Sykora

Rick Sykora

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Update:

GR recently lowered the LGK2 driver Xmax from 2.5 to 1mm. Decided to sim this in Bassbox. Here is what it looks like driven at 5 watts...

1655655897337.png


Likely explains more of what Amir experienced. It exceeds Xmax at 200 Hz in the supplied cabinet. Danny is now talking about an improved version of the driver. Wonder why (note this is a rhetorical question)?
 
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Rick Sykora

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Was recently made aware that Danny suggested that the supplied inductors may have been damaged in shipping. If so, not sure which shipping, but the windings would have been loose and shipping damage would likely be more of a random character. These inductors were clearly manufactured incorrectly and then shipped out by GR.

For the record, I had mentioned the poor inductor quality to his assistant prior to the review. There was no offer to replace them, and he blamed it on supplier problems. Seems just as likely that the drivers may not be up to spec either. All this could be handled by either sending a sample (as Amir had originally requested) or offering me some replacement parts. Of course, this would involve some admission of fault on GR's part. ;)
 
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sofrep811

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Was recently made aware that Danny suggested that the supplied inductors may have been damaged in shipping. If so, not sure which shipping, but the windings would have been loose and shipping damage would likely be more of a random character. These inductors were clearly manufactured incorrectly and then shipped out by GR.

For the record, I had mentioned the poor inductor quality to his assistant prior to the review. There was no offer to replace them, and he blamed it on supplier problems. Seems just as likely that the drivers may not be up to spec either. All this could be handled by either sending a sample (as Amir had originally requested) or offering me some replacement parts. Of course, this would involve some admission of fault on GR's part. ;)
Man, he is so ignorant he’s willing to put his company on the line. Sure, sales won’t be affected right now but the ASR review comes up when looking for a review on his speakers. Just send in a pair that represents exactly what you sell it the kit as. Simple.
 
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Rick Sykora

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Since GR did not offer a replacement for the (allegedly defective) LGK driver, started considering alternatives as I wanted to do something useful with the cabinet. I have a number of suitable drivers around. For comparable spend, the Dayton RS100 was a good match for the cabinet. As I mentioned in another thread, the Peerless NE123 is on sale at Madisound. I had planned another build thread for this effort, but along came the Copperhead speaker, and put this effort on the backburner. I was also preparing work on Directiva r2 but the design lead is now freed up and will resume my project manager role.

As you might guess, both the Dayton and the Peerless outperformed the LGK. I was also considering the Copperhead's driver but does not appear to be as good as the (very comprable) RS100. If there is some interest, let me know. Had some hope the Copperhead design would transplant into the GR cabinet, but after seeing the EAC measurements, am not encouraged.
 

Everett T

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Since GR did not offer a replacement for the (allegedly defective) LGK driver, started considering alternatives as I wanted to do something useful with the cabinet. I have a number of suitable drivers around. For comparable spend, the Dayton RS100 was a good match for the cabinet. As I mentioned in another thread, the Peerless NE123 is on sale at Madisound. I had planned another build thread for this effort, but along came the Copperhead speaker, and put this effort on the backburner. I was also preparing work on Directiva r2 but the design lead is now freed up and will resume my project manager role.

As you might guess, both the Dayton and the Peerless outperformed the LGK. I was also considering the Copperhead's driver but does not appear to be as good as the (very comprable) RS100. If there is some interest, let me know. Had some hope the Copperhead design would transplant into the GR cabinet, but after seeing the EAC measurements, am not encouraged.
What about this driver?

The port size may be an issue
 

617

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That Scanspeak disco unit is probably the nicest 4" being made, unless Satori has one I don't know about.

Perhaps my affection is an artifact of my increasinly antiquated skill designing passive filters, but this FR warms my heart:

10F/8424G
10F_8424G00-curve.jpg


I could build my own vandersteens with that thing. $113. I spend that much on peanut butter every month.
 

Everett T

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That Scanspeak disco unit is probably the nicest 4" being made, unless Satori has one I don't know about.

Perhaps my affection is an artifact of my increasinly antiquated skill designing passive filters, but this FR warms my heart:

10F/8424G
10F_8424G00-curve.jpg


I could build my own vandersteens with that thing. $113. I spend that much on peanut butter every month.
There are some old Ted Jordan 4" full range drivers that were pretty darn good, the problem, back then, was the cost. I'll try to find the measurements or have to email a friend to.
 
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