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 Post subject: GRS Planar Drivers
PostPosted: October 16th, 2020, 9:00 am 
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Parts Express is now selling a line of what appear to be copies of Bohlender Graebener planar drivers made by GRS. The BG drivers' prices have increased dramatically since the change in ownership and initial decision not to sell to the DIY community. The variations are interesting, including a narrower version of a BG8. If the FR plots are to be believed, the 12kHz peak is greatly reduced in both BG8 variations, but the FR is still not stellar. The GRS/BG3 variant FR looks excellent. The GRS/BG8 version sold is 8 ohms vs 4 for the BG PDR or 8 for the BG8Sversion. The GRS/BG3 version is 4 ohms same as BG.

The prices are still not cheap, but way more affordable than BG. If one is building line arrays, this is a big deal.

Has anyone tried them yet?

Data sheets are attached for the of the drivers. Here is a link to the fourth:

https://www.parts-express.com/pedocs/sp ... -sheet.pdf

There is also a closed back version of the "3":

https://www.parts-express.com/pedocs/sp ... -sheet.pdf

Again, great looking FR!

Stuart


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272-130--grs-pt5010-8-spec-sheet.pdf [622.45 KiB]
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272-126--grs-pt6825-8-spec-sheet.pdf [627.02 KiB]
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272-122--grs-pt2522-4-spec-sheet.pdf [1.28 MiB]
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 Post subject: Re: GRS Planar Drivers
PostPosted: October 16th, 2020, 9:30 am 
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I have tested both the GRS 3" and 10" planars in The Monoliths open baffles and they are not clones of the BG's, so both crossover and baffle mods would be needed for an existing design to use them.

They are also a bit different in size, so that makes mounting them for a comparison to listen an issue.

Be careful with measurements on them. Another person that did measurements melted his 3" planar diaphragm and not at high SPL levels. It can happen to the BG's as well.

All that said, still going to see what happens with some crossover mods. It is not going to be fast as I am still getting the basement back together after water damage repairs.


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 Post subject: Re: GRS Planar Drivers
PostPosted: October 16th, 2020, 10:13 am 
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The prices are still not cheap, but way more affordable than BG. If one is building line arrays, this is a big deal.

Has anyone tried them yet?

Hey Stu! A late friend of mine had speakers based on the BGs tied to a pair of Antique Sound Labs Hurricane tube amps. The sound had a breath-of-life liquidity-transparent quality not unlike Quads.

I don't think you could go wrong with a system constructed around those drivers.

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 Post subject: Re: GRS Planar Drivers
PostPosted: October 16th, 2020, 2:00 pm 
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Thanks Walt,

I'm working on it! 6 x BG8 with Fountek NeoX 3.0 in center of line.

Stuart


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 Post subject: Re: GRS Planar Drivers
PostPosted: October 16th, 2020, 2:09 pm 
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You may want to look at the theory here for line arrays -

http://www.xlrtechs.com/dbkeele.com/CBT.php


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 Post subject: Re: GRS Planar Drivers
PostPosted: October 16th, 2020, 2:43 pm 
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Stuart Polansky wrote:
Thanks Walt,

I'm working on it! 6 x BG8 with Fountek NeoX 3.0 in center of line.

Stuart


HOLY FAST-TRACK BAT-MAN!!! :o

I might suggest side wings over the full length -- maybe about 8-inches wide. Kind of like what Infinity did with their RS-1Bs.

That would extend the planars' bottom-end to better integrate with your woofers.


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Infinity RS-1Bs.jpg
Infinity RS-1Bs.jpg [ 73.91 KiB | Viewed 220 times ]

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 Post subject: Re: GRS Planar Drivers
PostPosted: October 16th, 2020, 10:07 pm 
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If you are going to make side wings you might want to consider making them different sizes on each side. John Whittaker and Rudi Blondia did a lot of research with a few years back with BG RD75 drivers in different baffles. They found that an asymmetrical baffle provided smoother in room response.


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 Post subject: Re: GRS Planar Drivers
PostPosted: October 17th, 2020, 6:23 pm 
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tomp wrote:
They found that an asymmetrical baffle provided smoother in room response.


I bet the room itself was asymmetric and the asymmetric baffle was used to compensate for the room deficiencies.

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 Post subject: Re: GRS Planar Drivers
PostPosted: October 17th, 2020, 6:52 pm 
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An asymmetrical wing works well with the BG drivers to keep the LF response and give really nice imaging with the small frontal area.

Here was my test fit of the GRS 3" and 10" planars in my existing open baffles for measurements.


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 Post subject: Re: GRS Planar Drivers
PostPosted: October 17th, 2020, 8:01 pm 
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I don’t consider that a “wing”. You have a half enclosure to avoid room reflection. A wing for me means a baffle. I read Toms statement to mean baffles of rich and left speakers are not identical.

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