Build of gr-research X-LS Encore

[Rick Sykora]

As I wrap up this build, I did complete my validation measurements. Here is the on-axis frequency response, 75db, gated at 1m:

Interestingly, I also measured after removing the damping, the response was almost identical. So, the impedance blip ugliness does not show up on a simple REW frequency response measurement. So, is it audible? I can demonstrate situations where I can hear, but this is not unique to this speaker, so will leave for another time/place.

 

[maty]

I have been looking for measurements of the new EVO series and its inside (building + crossover) for some time but there is no way. If Wharfedale has been right with the ribbon tweeter, then they will surely sound great.

In Audiocircle there is one that speaks wonders of Evo 4.4 he bought for his son.

• https://www.audiocircle.com/index.php?PHPSESSID=ucm1ne29ndb2vogcoivs6fdlf6&topic=168122.0
• https://www.wharfedale.co.uk/evo4-4/

- End off topic -

 

[Rick Sykora]

Mine is Curve Acoustics X-LS Encore, it's a prebuilt pair for South East Asian market and I assume is/was an authorized distributor for GR Research.

Guessing these are GR-modified AV123 X-LS speakers. Would explain why they have real circuit boards for the crossovers.

Is the gray foam removable?

 

[MZKM]

I have been looking for measurements of the new EVO series and its inside (building + crossover) for some time but there is no way. If Wharfedale has been right with the ribbon tweeter, then they will surely sound great.

In Audiocircle there is one that speaks wonders of Evo 4.4 he bought for his son.

• https://www.audiocircle.com/index.php?PHPSESSID=ucm1ne29ndb2vogcoivs6fdlf6&topic=168122.0
• https://www.wharfedale.co.uk/evo4-4/

- End off topic -

I too want to see how well that new lineup of their’s measures. I own the Jade 5 as I saw the Stereophile measurements of the Jade 7 were pretty good (I bought the 5 used for $1400 shipped I believe).

This is their first venture with AMT tweeters, so I wonder how they perform, as they have a more expensive Elysian lineup that also uses AMT tweeters, but not the same. I thought they manufacture their own drivers, but I find it weird how they made a dome midrange for the Evo and a regular style midrange for the Elysian (my Jade’s use a small aluminum midrange that looks like an Accuton, though it’s not).

 

[Rick Sykora]

Please either take the EVO discussion to another thread or start a new one.

Thanks!

 

[MZKM]

Please either take the EVO discussion to another thread or start a new one.

Thanks!

Sorry bout that.

Back to damping; if Amir is willing to measured with & without, will you make it so he is easily able to do so (say regular Phillips screws instead of hex screws, unless he has a hex screwdriver)?

I doubt damping has much of an effect on an FR measurement (unless there is a real nasty resonance), but I would expect the waterfall plot to show a difference.

 

[amirm]

Sorry bout that.

Back to damping; if Amir is willing to measured with & without, will you make it so he is easily able to do so (say regular Phillips screws instead of hex screws, unless he has a hex screwdriver)?

I doubt damping has much of an effect on an FR measurement (unless there is a real nasty resonance), but I would expect the waterfall plot to show a difference.

It would cost me an entire day to measure and document both ways. I don't want to do that. At this point, I will test with damping.

 

[Rick Sykora]

Ok folks, you heard it straight from Amir, the test speaker will include damping material.

Since Acousta-Stuf gave the best results in my testing, plan to use it. Will tear it down for a final sanding and, after a quick sound check, will be packing it to ship to Amir.

Thanks for your support and will look forward to Amir’s test results!

 

[bunkbail]

Guessing these are GR-modified AV123 X-LS speakers. Would explain why they have real circuit boards for the crossovers.

It was marketed as X-LS Encores though. They had all the models from GR's X series at that time as well.

Is the gray foam removable?

Yup the foams are not glued. They're just stuffed as is inside the cabinet.

 

[Rick Sykora]

It was marketed as X-LS Encores though. They had all the models from GR's X series at that time as well.


Yup the foams are not glued. They're just stuffed as is inside the cabinet.

Likely is some earlier gen version. It appears to have the bypass cap that the current X-LS has. Asked about the foam as it appears different than No Rez and does not have its adhesive backing.

If you really want to know, would check with Danny. Duke posted his contact info earlier in the thread.

 

[Rick Sykora]

Ok, the test speaker is almost back together and ready to ship. The port tube is press fit, so decided to glue it in place.

After reviewing the test results, I found indication that the foam/Acousta-Stuf combo might be slightly better, so checked with the designer and he preferred too. So the damping is now more comparable to the better speakers I have built.

This one will get a new box too. Often this is fancier work than the cabinet construction, but worth it to make sure it has the best possible chance to get to Amir intact.

 

[Canuck57]

Amir and Rick thank you so much for volunteering your time for this endeavor

 

[maty]

What interests me about those speakers is measuring the distortion of the drivers, especially the M-165 woofer. For tweeters I have been clear for years, waveguide with ribbon tweeter or coaxial.

• http://gr-research.com/gr-t3tweeter-1.aspx
• http://gr-research.com/m130woofer-1.aspx

 

[amirm]

And measure I shall.....

 

[Rick Sykora]

Did a final impedance and sound check. Never ceases to amaze me that seemingly small things can make a significant difference. With the port glued in, the box tuning is now spot on to the tuning that is posted on GR's website. Was not much but apparently air was leaking around the port tube cutout. What is also interesting is that the impedance test is done at a remarkably low output level and still is quite revealing. I only built my impedance test box a few years ago and would not build another speaker without it!

All is functioning and have built the new shipping box. Now just need to don my mask and drop off at shipper.

 

[maty]

Before I share the results of my testing on damping material for the X-LS Encore, I thought it might be useful to know the following:

1. I try to be as consistent as possible and only change one thing at time as I measure.
2. Unless otherwise specified, I do secure crossover boards with pan head screws and the underside of the board gets generous strips of butyl rubber. I also use butyl rubber to minimize potential component/wire vibration on the boards. So, while my intent is to keep the crossover adding any mechanical noise, the side benefit is changing the resonant modes of any panel where the crossover is mounted. For this speaker, the boards are mounted on the bottom and the lower inside of the right side panel.
3. While an impedance sweep is currently my best tool for identifying resonances, it may miss some and identify others that are potentially inaudible. Even if the designer publishes his curves, it is not always clear they are fully representative of flaws in the design. In my experience, the designer's may just post sim graphs or a golden measure. A really clean graph usually indicates a really well done implementation but may just an overly ideal one too. As we have seen with some well built commercial speakers, small resonances are not all that uncommon.

Here are my test cases based on materials on hand. For most cases, I only applied the material to the largest exposed areas (the top, the tops of the sides and the open part of the bottom):

1. 1/4" F13 felt (originally obtained to do diffraction reduction duty on front baffles)
2. 5/8" foam sheets (from Madisound and used in my Zaph kits)
3. Acousta-stuf fiber fill (2 ounces from a larger Parts Express bag) applied only in lower back of cabinet
4. Both 2 and 3

Results for Test #1 (Felt):

View attachment 72891
The felt notably blunted the ugliest of the resonances and indicates that they were likely due to standing waves formations. Still a bit of an issue at 275 Hz and a slightly greater one at 600 Hz.


Results for Test #2 (foam sheets):

View attachment 72892
Not much to say, although expected to be better than felt, looks about the same to me.

Test #3 (Acousta-stuf):
View attachment 72893
Here it seems less is more. While 2 ounces does not seem like much, it fills the back lower quarter of the cabinet. Best result so far, but maybe more is better?

Test result #4 (Foam sheet plus Acousta-Stuf)
View attachment 72894
My call is this is a bit of a draw. The 275 Hz blip seems slightly worse and the 600 Hz one is slightly better.

Hope you found this useful. My conclusion would be that Acousta-Stuf is sufficient for now. I want to see if I can isolate the remaining resonances, but probably at a point of diminishing returns. Another check I did was to see if the Bassbox sim indicates a port resonance, but the posted params for the woofer did not produce a good correlation with the real thing. So will have to measure the port directly. That is another test setup and will share later.

Finally, my brief listening tests were generally positive. My wife would probably tell you that I never met a speaker I did not like though.

Re: Constrained layer damping vs mass loading in speaker cabinets by ginetto61
https://www.audiocircle.com/index.php?topic=170625.msg1813364#msg1813364

[ Speaking of cabinet damping nothing beats lead ... i know ... it is very toxic to work with But some years ago me and a friend glued and stapled some lead sheets

to the internal sides of two Dynaudio msp 110 speakers i still have here (i should replace the woofers with other ones better but i am scared by the lead inside

They got very heavy indeed. Very.

The effect on the sound was terrific ... the instruments with a lot of bass content sounded completely out of the box and extremely clear

Like all the rest of the instruments by the way

At a point the sound was so out of the cabinets that i thought like the speakers were disconnected

I take off the cables and of course the sound disappeared.

What i mean is that since then i am very convinced that mechanically dead speakers sound much better. ]

 

[Rick Sykora]

This one is a wrap for now. UPS estimates it will be to Amir by Monday!

 

[KaiserSoze]

Before I share the results of my testing on damping material for the X-LS Encore, I thought it might be useful to know the following:

1. I try to be as consistent as possible and only change one thing at time as I measure.
2. Unless otherwise specified, I do secure crossover boards with pan head screws and the underside of the board gets generous strips of butyl rubber. I also use butyl rubber to minimize potential component/wire vibration on the boards. So, while my intent is to keep the crossover adding any mechanical noise, the side benefit is changing the resonant modes of any panel where the crossover is mounted. For this speaker, the boards are mounted on the bottom and the lower inside of the right side panel.
3. While an impedance sweep is currently my best tool for identifying resonances, it may miss some and identify others that are potentially inaudible. Even if the designer publishes his curves, it is not always clear they are fully representative of flaws in the design. In my experience, the designer's may just post sim graphs or a golden measure. A really clean graph usually indicates a really well done implementation but may just an overly ideal one too. As we have seen with some well built commercial speakers, small resonances are not all that uncommon.

Here are my test cases based on materials on hand. For most cases, I only applied the material to the largest exposed areas (the top, the tops of the sides and the open part of the bottom):

1. 1/4" F13 felt (originally obtained to do diffraction reduction duty on front baffles)
2. 5/8" foam sheets (from Madisound and used in my Zaph kits)
3. Acousta-stuf fiber fill (2 ounces from a larger Parts Express bag) applied only in lower back of cabinet
4. Both 2 and 3

Results for Test #1 (Felt):

View attachment 72891
The felt notably blunted the ugliest of the resonances and indicates that they were likely due to standing waves formations. Still a bit of an issue at 275 Hz and a slightly greater one at 600 Hz.


Results for Test #2 (foam sheets):

View attachment 72892
Not much to say, although expected to be better than felt, looks about the same to me.

Test #3 (Acousta-stuf):
View attachment 72893
Here it seems less is more. While 2 ounces does not seem like much, it fills the back lower quarter of the cabinet. Best result so far, but maybe more is better?

Test result #4 (Foam sheet plus Acousta-Stuf)
View attachment 72894
My call is this is a bit of a draw. The 275 Hz blip seems slightly worse and the 600 Hz one is slightly better.

Hope you found this useful. My conclusion would be that Acousta-Stuf is sufficient for now. I want to see if I can isolate the remaining resonances, but probably at a point of diminishing returns. Another check I did was to see if the Bassbox sim indicates a port resonance, but the posted params for the woofer did not produce a good correlation with the real thing. So will have to measure the port directly. That is another test setup and will share later.

Finally, my brief listening tests were generally positive. My wife would probably tell you that I never met a speaker I did not like though.

According to GR-Research the tweeter's resonance is at 600 Hz. If this is correct it will explain the little glitch at 600 Hz but not the bigger peak at about 850 Hz.

For standing waves that set up between reflective parallel surfaces, the distance between the surfaces must be 1/4 of the wavelength, or 3/4 of the wavelength, or 5/4 of the wavelength, etc. Generally D = n x WL/4, where D is the distance, n is any odd integer, and WL is the wavelength. Solving for WL, the general equation for the wavelengths of standing waves is WL = 4D/n. One of the interior dimensions (top to bottom) is evidently 12". For this dimension, 4D = 48"; 4D/3 = 16", 4D/5 = 9.6", etc. In terms of frequency, for n = 1, f = 281 Hz; for n = 3, f = 844 Hz; for n = 5, f = 1.4 kHz, etc.

The standing wave that sets up between the top and bottom with 3/4 of the wavelength matching the 12" distance has full wavelength equal to 16", corresponding to 844 Hz, which is right on the mark. It is curious that this one resonance would appear so much stronger than the others, but this appearance is due largely to the fact that this frequency is very close to the tweeter's resonance, i.e., the impedance for both of the parallel circuit paths is high in the vicinity of 850 Hz.

If either circuit path has low impedance at a frequency where the impedance of the other path is high, the higher impedance is masked by the lower impedance. For the woofer's in-cabinet resonance and the port resonance, the tweeter path is nearly an open circuit at these lower frequencies, and these are strong resonances, so these impedance peaks routinely show up. There are likely two reasons why the impedance peaks associated with cabinet resonances do not routinely show up the same way. The masking effect of the tweeter path is ordinarily stronger at the higher frequencies where most of the internal resonances occur, and these resonances are likely not nearly as strong as the woofer's in-cabinet resonance and the resonance of the port. But in this particular case the impedance of the tweeter path is also coincidentally high at the frequency of this cabinet resonance. It occurs to me that when measuring the impedance of a completed speaker, with the drivers installed in the cabinet, that in order to obtain the greatest and most useful amount of information, it should probably be done with the tweeter's path (not the tweeter itself) disconnected from the input terminals.

In any case, the frequency response is evidently not affected, so it doesn't matter except that good scientific practice is always to come up with a hypothesis that can be tested.

 

[Mixed_Messages]

Appreciate the work and build.

Are there any commercially available speakers that do not have any damping material installed?


For the car analogy, I’m thinking it’s like getting a tire without air installed?

I believe the Buchardt s400s don't have any damping in them. All technical and listening tests didn't deliver any difference..

 

[Rick Sykora]

Realized I have yet to follow-up on any potential port resonance. Once I got the Bassbox model to work, it showed a small potential port resonance around 1200 Hz. When the X-LS Encore was measured without dampening, the was a slight deviation around that same frequency. It went away with damping applied, so probably not an issue of any major import this time.