GRS-3 vs Neo 3

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Captainhemo

Re: GRS-3 vs Neo 3
« Reply #60 on: 30 Sep 2020, 02:52 pm »
GRS drivers arrived today.  Getting a set of Radian as well.  Will do full comparison of original BG, RADIAN and GRS and start new thread once complete. 

Greg


Greg , 
Which Radian's do you have  coming  ?

jay

studiotech

Re: GRS-3 vs Neo 3
« Reply #61 on: 30 Sep 2020, 03:01 pm »
Jay, I'm ordering the LM8K.  Might as well test an variations of the 8.  I'm not personally interested in the smaller models as I'll continue to use Raal for top end.   

Hobbsmeerkat

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Re: GRS-3 vs Neo 3
« Reply #62 on: 30 Sep 2020, 05:18 pm »
Some bad news..  :duh:

It was a nice cool overcast day, so I did my testing outside, but noticed the tests weren't as clean as thry should be & slowly getting worse, when I looked at my GRS driver, I think the heat from the sun softened the diagram or the foil adhesive too much, shifting the traces away from the center...
It's leading to a lot of heavy distortion. Along with a loss in the upper mid range from 4K-10K.

Before:


After:


So if you plan to do testing outside, keep it in the shade!  :nono:
Even my Neo3 shows signs of the same problem, tho because it had far less testing its not nearly as bad of shape..

On the better hand, I did get some interesting results from using the plastic rods. Having 3 tall rods (as seen in 2nd pic) causes a MASSIVE hole in the response around 8K hz, it's caused by the outer two rods. However, the inner rod actually allows for a small 3-5db rise in the 18-20K Hz range, without the drop at 8K.

Hobbsmeerkat

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Re: GRS-3 vs Neo 3
« Reply #63 on: 30 Sep 2020, 05:34 pm »
Hoo boy it's MUCH WORSE than I thought...

I opended up the GRS-3 to find this:


The diaphragm is absolutely SHREDDED. :o
I'm guessing the heat & higher output absolutely destroyed the driver... Bummer.

I'm guessing the Neo3 is going to look the same, but to a lesser extent.. *sigh* lol

AKLegal

Re: GRS-3 vs Neo 3
« Reply #64 on: 30 Sep 2020, 05:59 pm »
Yikes!  How long were they in the sun? 

Hobbsmeerkat

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Re: GRS-3 vs Neo 3
« Reply #65 on: 30 Sep 2020, 06:04 pm »
I'd say roughly hour & 15 minutes or so judging by the time stamps of the tests I ran.

Danny Richie

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Re: GRS-3 vs Neo 3
« Reply #66 on: 30 Sep 2020, 06:43 pm »
I'd say roughly hour & 15 minutes or so judging by the time stamps of the tests I ran.

And that is why we use Kapton film on ours instead of Kaladax.

HAL

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Re: GRS-3 vs Neo 3
« Reply #67 on: 30 Sep 2020, 07:11 pm »
It looks more like power got them as there looks like 3 burn places in the voice coil metalization, if I see the picture correctly.

Here are the GRS 3" and 10" planars in the Super Mini Baffles with CLIO Pocket using the latest 2.11 version software and the Log Sweep test.  The measurements are each on the center axis point of the drivers. 

Had limited measurements outdoors due to wind, power tools and traffic around the area.  Not able to do the original GR and BG drivers in the other baffle.

I am keeping the drive power to the planars down in level to not do the same as I had that happen to a BG NEO3-PDR once. 



Hobbsmeerkat

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Re: GRS-3 vs Neo 3
« Reply #68 on: 30 Sep 2020, 08:26 pm »
I'd imagine it was probably a fair bit of both, but if i need another standard Neo 3 it'll be one of Danny's.

In the meantime, I've already ordered another GRS-3 that should arrive Saturday, so i can do more testing with the rods since ive found that there are some visible results worth checking out.
But I'll keep the testing limited to indoors and around 60dB like my previous tests, but it was nice to see the cleaner waterfall and graphs from testing in an open space while they lasted.. :P

emailtim

Re: GRS-3 vs Neo 3
« Reply #69 on: 30 Sep 2020, 10:20 pm »
I'd imagine it was probably a fair bit of both, but if i need another standard Neo 3 it'll be one of Danny's. ...

Couple of thoughts.

Could the rods be acting as insulators, preventing heat dissipation/cooling ???

If you used glue, could it have acted as a solvent weakening membrane ???




Hobbsmeerkat

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Re: GRS-3 vs Neo 3
« Reply #70 on: 30 Sep 2020, 10:27 pm »
I finally got a chance to do a little more digging thru the results and you can see in the distortion graph where the diaphram failed..


Yellow: Good     Green: Failed

That said, heres how it reacts with the faceplate rods:

Teal: Stock
Magenta: Outer rods only
Purple: Center rod only

Reminder: The tweeter was long ruined at this point, so once the replacement arrives, ill be re-testing the different rods to see if the differences percist/change.

Couple of thoughts.

Could the rods be acting as insulators, preventing heat dissipation/cooling ???

If you used glue, could it have acted as a solvent weakening membrane ???

They failed before I ever put the rods on. I actually only noticed the issue once I put the rods on. Even on a cloudy day with a light breeze, it was too much heat for the kaladex to handle under the stress of the movement.

I didnt use glue, I used thermal transfer tape intended for small heatsinks on small electronics.

emailtim

GRS PT6825-8 8" Planar Mid/Tweeter 8 Ohm
« Reply #71 on: 3 Oct 2020, 07:01 pm »
If this should be moved to another thread, please let me know.

I received two of the GRS NEO8 "wide" drivers and have placed them in two 20" tall x 8" wide x 3/4" thick MDF baffle with a 16" side wing (Danny, I watched your latest video =).  Drivers are mounted in the back with the rectangular hole and the vertical edges of the baffle rounded with a quarter-round bit.

I specifically asked Parts-Express why the website description stated low distortion above 500Hz while the frequency chart showed the NEO8's going lower than 500Hz.  They avoided the question in their response.

"...  With the ability to provide low distortion output from 500-20,000 Hz ..."

The following plot is an in-room THD response of both drivers.  You can see they have rising distortion under 500Hz ([1.5% - 2%] up from 0.5%), thus the blurb on their website appears to be accurate.


Hobbsmeerkat

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Re: GRS-3 vs Neo 3
« Reply #72 on: 3 Oct 2020, 07:59 pm »
I would say I'm surprised by the differences in THD, but the distortion is still lower in percentage than that between my now dead Neo 3 & GRS-3. Esp in the 1.2K-2K range. However, if that same distortion hump doesnt appear on my 2nd driver it might all be down to simple manufacturing tolerances...  :scratch:

But it is interesting that both GRS-3 & GRS-8 show increasing distrortion below full extent of their bottom end.. I'm guessing it has to do with the distance the diaphram is able to travel before hitting the damper layers/magnets?
I'm curious how the GRS-10 acts in that regard. I imagine it'll play down lower but will start hitting distortion issues around 300Hz?

I'm also really curious about the jagged pattern above 2.5K...

emailtim

Re: GRS-3 vs Neo 3
« Reply #73 on: 3 Oct 2020, 09:16 pm »
"... I'm also really curious about the jagged pattern above 2.5K...   

The jagged pattern on the right is a product of using the option "Use Harmonic Freq as Reference" option.

Hobbsmeerkat

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Re: GRS-3 vs Neo 3
« Reply #74 on: 3 Oct 2020, 09:35 pm »
"... I'm also really curious about the jagged pattern above 2.5K...   

The jagged pattern on the right is a product of using the option "Use Harmonic Freq as Reference" option.

Gotcha

Hobbsmeerkat

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Re: GRS-3 vs Neo 3
« Reply #75 on: 4 Oct 2020, 02:25 pm »
Finally got a chance to test my new GRS-3 with 3 different rod sizes.
Small round-overs, Medium and tall "waveguides"



Rather than post 1000 charts again I'll just be sharing the MDAT file for y'all to look thru. Each measurement is labeled in the notes section, with the last measurement being stock measurement.

MDAT:
https://drive.google.com/file/d/1EHCbDWIFV7KVVfvPiBZ49gwto_B2_DBd/view?usp=drivesdk

SPL


THD


It maybe the due to the differences in testing, but the SPL graph isnt as good as the previous sample, and measures more similarly to the damaged model? That said, the THD graphs are a lot more consistent, esp above 1K Hz.

Hobbsmeerkat

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Re: GRS-3 vs Neo 3
« Reply #76 on: 9 Oct 2020, 07:40 pm »
Been busy lately and its only gunna get busier next week since my job is currently understaffed thanks to people in quarantine or Vacation, so I'll probably be out of pocket for the next several days.

That said, I designed & am currently printing a "super-mini" clone front baffle for testing the GRS-10 (not able to include a mount for the GRS-3/Neo3 tho. Should be finished early tomorrow morning and ready for gluing/assembly, and I'll do my testing once the opportunity arrises, but i can't make any promises it'll be any time in the immediate future. Esp since I've also got my housemates schedules to contend with, on top of working everyday until Thursday when I leave for Dallas, TX.

Broncosaurs

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Re: GRS-3 vs Neo 3
« Reply #77 on: 9 Oct 2020, 08:49 pm »
Don't take too long, we are waiting... :popcorn:

Hobbsmeerkat

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Re: GRS-3 vs Neo 3
« Reply #78 on: 10 Oct 2020, 02:52 pm »
Print finished just as soon as i got home for my lunch break!
Its not perfect, but here's the rough test fit before i permanently epoxy the two halves together! :thumb:





Bonus is i can use tape/cardboard to create a faux side wing to match the original design. :D


Hobbsmeerkat

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Re: GRS-3 vs Neo 3
« Reply #79 on: 11 Oct 2020, 11:57 am »
Here are some quick & dirty graphs i made this morning:

SPL:


THD:



Waterfall:


Ill post better ones after i get off work, cuz i know the waterfall & THD only show to ~500Hz

Okay! Graphs are updated! The distortion below 400Hz doesnt look good, but it also seems to be related to the fall or rise in SPL. Namely the dips at 300&400Hz and then down to 100Hz.
The next chance I get to run some tests, I want to attempt with addition of a side wing to see if it helps smooth out the response and helps extend the bass & reduce the distortion in those regions as well.
« Last Edit: 11 Oct 2020, 06:05 pm by Hobbsmeerkat »