GR Research X-LS Encore Kit Speaker Review

[thebabyparrot]

When I was younger I was obsessed with acquiring the GR Research LS6.

https://img.usaudiomart.com/uploads...23-ls6-line-source-speakerspiano-rosewood.jpg

 

[GXAlan]

Just thought of something that I don't know why I didn't think of prior. Why does no one 3D print cabinets? Especially big companies that can use simulations to verify internal designs especially...?

Harman is one of the early adopters of 3D printing for prototypes. The real challenge is cost.

You can definitely 3D print cabinets in materials such as titanium but it will be limited to relatively small build plates and Magico level pricing. Applying this technology to headphones, however, is a different story.

Printing in resins will be plenty strong for a speaker cabinet but again, simulations to verify internal designs would be needed. The strength arises from the possibility of internal latticing.

If there are speaker designers here that want to explore production grade 3D printing, send me an PM.

 

[Thomas_A]

With DIY kits, the focus is on making the speaker cabinet as simple as possible to reproduce.
Rounded side edges would certainly improve the radiation pattern. However, the radius must have a certain size for this.

This is nothing new, however, as the magazine Hobby-Hifi, for example, already showed in detail 20 years ago.
Here is a small excerpt from the article (Have removed the German comments from the picture, the results speak for themselves, the frequency responses 0° to 60° are shown):
Source: http://hobby-hifi.de/Archiv/01/05_01/05_01.html
View attachment 75493
The test object had a baffle width of 0.17m. This means that the distance of the tweeter to the lateral edge of the baffle is 0.85m, which at a wavelength corresponds to the frequency of 4kHz - exactly the problematic frequency range.

UPDATE: The percentages in the image refer to the baffle width of the loudspeaker. In order to achieve a similar effect as in the bottom diagram with a 0.3m wide loudspeaker (problematic frequency range would be around 2.3kHz), the radius of the rounding must be 45mm.

Two important remarks on this:
- A radius that is too small further exacerbates the problem of edge diffraction - the frequency response becomes even more unsteady.
- Rounding the side edges reduces the "effective" baffle width, the effect of edge diffraction shifts to higher frequencies and "smears" the edge diffraction over a wider frequency range, which means that the crossover will most likely have to be adjusted.

Nowadays, even for hobby loudspeaker developers, it is no longer a problem at all to optimize the radiation of a loudspeaker through simulation (before the first prototype must be produced)- it is almost child's play

You can reduce some variations but in this case you cannot fix it. The peakng off-axis is just above the x-over fr and relates to directivity mismatch.

 

[ctrl]

You can reduce some variations but in this case you cannot fix it. The peakng off-axis is just above the x-over fr and relates to directivity mismatch.

If you can explain that in more detail, I can't follow you.
The combination 6.5'' woofer with 1'' tweeter is actually unproblematic in terms of matching radiation (if CD behaviour is not the goal).

 

[mhardy6647]

This is also quite a deep speaker so don't think about using it on the desktop. I evaluated it as a hi-fi speaker in far field.

Alternatively -- perhaps this is a nearfield speaker that is simply crying out for what I call a "Perry White Editor's Desk"

 

[Jmitch3]

Here is his 0/10/20/30/40 horizontal graphs (1/3 octave) vs what Klippel got:
View attachment 75449View attachment 75450

7kHz peak and 10kHz dip are main differences.

As before, I wonder if the ~3kHz bunching of off-axis responses could be tamed with rounded edges.

its pretty much accepted generally on the gr forum at audiocircle a 3/8 roundover is necessary. Id like to see a review of these speakers with captainHemos flatpack with norez and proper cabinet construction (w roundovers).

 

[Deleted member 2944]

its pretty much accepted generally on the gr forum at audiocircle a 3/8 roundover is necessary. Id like to see a review of these speakers with captainHemos flatpack with norez and proper cabinet construction (w roundovers).

Well, if it's accepted in the GR forum, it must be the straight scoop.

Roundovers won't change the directivity aberration at 2khz. That's baked into the system because of the baffle dimensions, driver-spacing and crossover configuration. No-Rez or roundovers might change the "rippling" of the response in various places, but it won't alter the inherent shape.

To me, this is a perfectly fine set of small speakers for little money. You could do a lot worse.

Dave.

 

[TNT]

To have "pollen in the noise" is never recommend ;-D
Didn't know that AP had released that detector

//

 

[KaiserSoze]

These speakers rate better than the B6.2 (with subs 7.6 over 7.2), score the same as the much more expensive Buchardt S400, and are slightly cheaper than the Zaph 5.2 DIY kit (which performed poorer on a subjective basis). Yeah, the XLS Encores aren't earth shattering but I'd say they deserve a little more credit.

That being said, I do agree that DIY is seldom about getting the best deal out there. I don't include labour when I budget for my kits, as I take the view that I'm paying for the opportunity to play, rather than cutting on costs with labour. A detriment to my wallet for sure! Heh.

I think we agree that it all depends on the individual situation and the individual's reasons for wanting to build speakers. But notwithstanding that this speaker earned a rating better than the B6.2, I think we can agree that this kit is not a way to get more for less money. For anyone looking to get more for less, this isn't it. One of those HiVi kits might offer that opportunity, although with the HiFi kits this is only a possibility, not a certainty. To my way of thinking, the only scenarios where a kit speaker (or a speaker designed and built from scratch) is likely to get you more for less is when the finished speaker will be comparable to regular store-bought speakers that are prohibitively expensive for most people, but where the cost to build it is considerably less than the cost of the store-bought speaker. It is with speakers of this type that there is opportunity to get more for less, because with speakers of this type there is generally high profit for the manufacturer and high markup for the retailer and for the distributor. From this standpoint, it is evident that at the low end of the cost range, the only way that kit speakers make a lot of sense is if the cabinets are included and the total cost is no more than what it would cost to buy a similar speaker at retail. But then again, as you point out, if the reason for building the speaker is for the personal satisfaction of having done it, and you are willing to buy for that satisfaction, then you have reason to buy a speaker such as this one. People who don't care about that much personal satisfaction and who are mainly interested in getting more for less will probably be more satisfied with one of those two HiVi kits, which seem to offer a lot a value.

 

[TBomb25]

Yes, they were AV123 speakers sold by Mark Schifter & co. I had the original X-LS and I did not like them (although the cabinets were amazing to look at). I thought they were thick sounding in the upper bass/lower mids and rolled off at the top - but am not sure how identical they were to these in terms of components.

The Encore version uses a much better tweeter i had the SLS Encore, The Xtatic, and the original XLS...i also owned the Swan m2.2 waaaay before they made a kit out of it. Strangly the original XLS and the Swans had a very similar sound both warm and kinda rolled off of course the Swan had much more detail and a way bigger soundstage...

 

[xarkkon]

its pretty much accepted generally on the gr forum at audiocircle a 3/8 roundover is necessary. Id like to see a review of these speakers with captainHemos flatpack with norez and proper cabinet construction (w roundovers).

Interesting, why 3/8 roundovers? Most of the forums I've seen tend to recommend chamfers, thought I can't say I understand the science of why... heh.

 

[KaiserSoze]

It is a problem as I see that the directivity error cause peaking in the 2-4 kHz region, which IMO will cause some harsh sound on soprano and female voices. I doubt there is a fix using rounded edges, but a wider baffle might help some + putting the cross-over at 3 kHz. + felt pads on each side of the tweeter.

The off-axis plateau in that range will almost certainly be audible although "harsh" might not be the best word to describe it (except for lack of a better word that comes to mind ...). As you say, rounding the edges is not likely to have any effect on this. In fact if it has any effect it will be the opposite of the intended effect because the 1st peak in the diffraction ripple occurs right in the middle of the response dip below the crossover frequency, i.e., the response dip that is due to the woofer's high directivity at frequencies slightly below the crossover point.

The only modification that would likely help would be to use a modest waveguide. A plastic waveguide bought online would add a small amount of additional cost to a speaker that already is not a strong value. This will require additional work, not just construction work. The tweeter's high-pass filter will need to be adjusted and to do this properly each component in the high-pass filter will have to be changed, the only likely exceptions being padding resistors if there are any. (The reason this becomes necessary is that the waveguide will affect the on-axis response as much as it affects the off-axis response. The plateau in the off-axis response goes away because acoustic power in that frequency range is redirected from the sides to the front.) The obvious question is whether this speaker is deserving of this kind of additional effort. Personally, I think that from a value perspective it is already questionable. Although, if the directivity mismatch were corrected, the value would increase. But then you still have the somewhat high distortion below 200 Hz, which depends on how loudly you expect to play it.

 

[Frank Dernie]

Harman is one of the early adopters of 3D printing for prototypes. The real challenge is cost.

You can definitely 3D print cabinets in materials such as titanium but it will be limited to relatively small build plates and Magico level pricing. Applying this technology to headphones, however, is a different story.

Printing in resins will be plenty strong for a speaker cabinet but again, simulations to verify internal designs would be needed. The strength arises from the possibility of internal latticing.

If there are speaker designers here that want to explore production grade 3D printing, send me an PM.

I retired 10 years ago so am well out of date.
When I first was aware of rapid prototyping, the predecessor of 3D printing, it was incredibly expensive, my first view of it was a prototype cylinder head casting design which was really interesting and despite being very expensive vfm in getting the production tooling right. Probably mid 1980s.
Many years later we used the technique for wind tunnel model parts but the problem was still cost and making stiff enough parts from available materials.
A bit later we started using bits on the racing car but only non structural bits like wiring harness covers.
Do you make 3D printed parts now?
I have only seen the technique for prototyping or low production run where cost was not a problem.
Has the process got good/cheap enough for production parts yet?
IME one wouldn’t use the process anywhere where you could see the part - surface cosmetics not a strong point back when I was using it!

 

[MZKM]

Interesting, why 3/8 roundovers? Most of the forums I've seen tend to recommend chamfers, thought I can't say I understand the science of why... heh.

Air likes to see smooth transitions, which is why good horn designs aren’t like a megaphone, take a look at some Avantgrade horns.

The same physics applies to the baffle, a flat edge isn’t great, chamfered is better, and roundover even more so. I also think cabinets with curved sidewalls help.

B&Ws teardrop tweeter design for instance is really good, super curved and slowly tapers to a point.

 

[GXAlan]

Do you make 3D printed parts now?
...
I have only seen the technique for prototyping or low production run where cost was not a problem.
Has the process got good/cheap enough for production parts yet?

I am involved with 3D Printing in titanium alloys for medical implants.

It's used in production for medical implants, automotive and jet engines.
https://www.3dprintingmedia.network/bmw-additive-manufacturing/

https://www.ge.com/news/reports/epi...explains-3d-printing-will-upend-manufacturing

https://www.ge.com/additive/stories/new-manufacturing-milestone-30000-additive-fuel-nozzles

It has not been used in production for consumer electronics yet but is used for sports
https://www.superfeet.com/en-us/me3d
https://content.riddell.com/Diamond/


The common thread is that you can't use 3D printing for prototyping what you can also build traditionally. You use it when you need to control mechanical properties precisely, which would be great for speaker enclosures and headphone enclosures...

 

[xarkkon]

Air likes to see smooth transitions, which is why good horn designs aren’t like a megaphone, take a look at some Avantgrade horns.

The same physics applies to the baffle, a flat edge isn’t great, chamfered is better, and roundover even more so. I also think cabinets with curved sidewalls help.

B&Ws bullet tweeter design for instance is really good, super curved and slowly tapers to a point.

Thanks! Time to get a roundover bit for the xls encores kit that I'll get to at some point...

 

[uwotm8]

Yeah, Revels are smoother, but overall curve shape...

 

[jhaider]

Well to be fair the main reason to DIY is not to save money... Well maybe for a few folks & sometimes it is a nice icing on the cake.
Really IMHO, DIY is because you want to learn, be involved, get dirty, take pride in your finished product even if the lines are crooked.
It is fun!
I enjoy buying "complete" products as well but nothing compares to DIY for that blood sweat and tears personal story.

I (intentionally) did not limit my remarks in the post you quoted commercial or finished speakers in the post you quoted. I don't know the kit market well, but $250 intuitively sounds very expensive to me for 4 generic Indian-made plastic frame drive-units combined without any thought to integrating dispersion patterns, and what looks like a 4 or 5 component crossover.

I also get the idea of wanting to build something just to do it, but by the same token one would think a person values her time enough to do so when the result is something not easily purchased. That doesn't mean "expensive," it means "different." For example, Linkwitz Pluto or LX-Mini aren't expensive, but if you want to experience that kind of unique design you have to build it. However, 6.5" 2-way dispersion disruption generators are a penny a gross on the new or used markets. Building one of those is the equivalent of trying to bake Wonderbread at home. Sure you can do it, but why?

 

[HighImpactAV]

When I was younger I was obsessed with acquiring the GR Research LS6.

I have two pairs for sale.

 

[ctrl]

Okay, there were some statements in the last posts that I can't understand - could partly be due to the translation.

Therefore I would like to show in a simplified way what is possible by changing the baffle, with unchanged cabinet dimensions - similar to the Philharmonic-BMR.

To keep my effort low, I use chassis simulations that are already on my hard disk. As woofer I use the SB17NAC35 and as tweeter the Seas-DXT, because the tweeter of the Encore also has a small waveguide. The cabinet dimensions are the same as in the Encore kit.

The fact that cancellations occur around the crossover frequency in the vertical radiation of vertically stacked drivers no longer needs to be explained, therefore the horizontal radiation is mainly considered.

If not stated otherwise, the normalized horizontal radiation pattern up to 90° is shown in 15° steps. To save computing time, the simulation is only reliable up to 7-8kHz.

First, let's have a look at the radiation pattern with a dome without wave guide - only the tweeter simulated:

A certain similarity to the complete loudspeaker measured by @amirm cannot be denied:

its pretty much accepted generally on the gr forum at audiocircle a 3/8 roundover is necessary.

Then the next thing we'll look at is what happens with a 3/8'' rounding - only the tweeter simulated:

This is certainly an improvement and should possibly work without adjusting the crossover.


Next consideration now would be to shift edge-diffraction most far to high frequencies, because then
a) the crossover remains free of interference
b) by using the small waveguide the radiation at high frequencies is still controlled and the edge diffraction is lower

First of all we lead the rounding as close as possible to the tweeter. The drivers have been moved upwards while maintaining their spacing (would have to be simulated in detail to see if this is really advantageous) - only the tweeter simulated:

That looks pretty good, the crossover-region at 1.8kHz is now completely interference-free in the radiation and the radiation of the woofer should not cause any problems anyway.

The edge-diffraction now causes us problems around 5kHz.

Our small waveguide (here the Seas-DXT instead of the T26SG used in the kit) should help us and tame the interference a little bit - only the tweeter simulated:

The optimization of the Encore kit is finished - it is as simple as that - please donate to @amirm , he needs a new handyman



But while we're at it, how would a complete loudspeaker with the SB17NAC plus Seas DXT as a tweeter simulate/measure with these dimensions?

Therefore we roughly simulate a crossover with [email protected]:

... and look at simulated end results:

Horizontal normalized sonogramm +-180°

Vertical normalized sonogramm +-180°

...and there goes the forum speaker